YEAR BOOK 95

The President's ReportJuly 1,1995-June 30, 1996

• CARNEGIE INSTITUTION OF WASHINGTON •

OFFICE OF ADMINISTRATION1530 P Street, N.W.Washington, DC 20005-1910(202) 387-6400President: Maxine F. SingerDirector, Administration and Finance: John]. LivelyDirector, External Affairs: Susanne Garvey

DEPARTMENT OF EMBRYOLOGY115 West University ParkwayBaltimore, MD 21210-3301(410) 554-1200Director: Allan C. Spradlmg

DEPARTMENT OF PLANT BIOLOGY290 Panama StreetStanford, CA 943054101(415) 325-1521Director: Christopher Somervilk

GEOPHYSICAL LABORATORY5251 Broad Branch Road, N.W.Washington, DC 20015-1305(202) 686-2410Director: Charles T. Prewitt

DEPARTMENT OF TERRESTRIAL MAGNETISM5241 Broad Branch Road, N.W.Washington, DC 20015-1305(202) 686-4370Director: Sean C. Solomon

THE OBSERVATORIES LAS CAMPANAS OBSERVATORY813 Santa Barbara Street Casilla 601Pasadena, CA 911014292 La Serena, Chile(818) 5774122Director: Augustus Oemfcr, Jr., The Crawford H. Greenewak ChairDirector, Las Campanas: Miguel Roth

Carnegie Institution Web site; http://www.ciw.edu

Library of" Congress Catalog Card Number 346716ISSN CCW-OttoX; ISBN 0^727^6744Printing by KirK Litfv^nifliic Company, Inc.Comp»*Mtu*n vuth AJrhe PageMakerPecemkr \Wfr

Contents

Presidents Commentary (Singer) 1Losses, Gains, Honors 10Contributions, Gifts, and Private Grants 15

• The Observatories

Director's Introduction 21The Sky at Meter Wavelengths (McCarthy) 23Lurking Galaxies (Dalcanton) 31Personnel 37Bibliography 39

• Department of Terrestrial Magnetism

Director's Introduction 47Time Scales and Stellar Evolution (Graham) 50Star Dust in the Laboratory (Alexander) 57Personnel 65Bibliography 67

• Department of Embryology

Director's Introduction 73Mice Flip Over New Genetic Techniques (Dyrnecki) 77Modem Genetics: A Modular Mis-expression Screen in.

Drosophik (R0rth) . 82Personnel 89Bibliography 91

(continued)

Yi \H fix 'K ^5 • C'\K\I i Al hoTHVIk >\

• Department of Plant Biology

Director's Introduction 95How Plants Protect Themselves from Damage by Excessive

Sunlight (Niyogi, Grossman, and Bjorkman) 99The Changing Carbon Cycle, from the Leaf to the Globe (Field) .. 106

Personnel 113Bibliography 115

• Geophysical Laboratory

Director's Introduction 119Isotopic Tracers of Climatic Changes in the Australian

Outback (Fogel and Johnson) 121Ancient Structures: Probing the Chemistry of Organic Matter

Diagenesis (Cody) 128Ultrahigh Metamorphism and the Qinglongshan

Anomaly (Rumble) 137Personnel 140Bibliography 142

Extradepartmental and Administrative

Personnel 149Publications and Special Events 150Abstract of Minutes of the 104th Meeting of the Board 151Bylaws 153

Financial Statements .. •, 162

Index. 175

C?me#ie Institution of Washing >n is committed to the national policy of fair treatment of allemployees in .ill aspects of employment. The Institution Joes not discriminate against any personon the kw» at race, color, religion, HJX, national or ethnic origin, age, disability, veteran status, or.my other baai* prohjhiteJ h\ applicable law. This pt licy ctwers all pri>grams, including adminis-trirti»*n ii ifA eJuc.1tion.4l pioftjram, aJmiK^nm ot qualified student!* as fellows, and empltfyment

j d

President and Trustees

PRESIDENTMaxine E Singer

BOARD OF TRUSTEESThomas N. Urban, Chairman

William I. M. Turner, Jr., Vice-ChairmanWilliam T. Golden, Secretary

Philip H. Abelson William R. Hearst IIIWilliam T. Coleman, jr. Richard E. HeckertJohn E Crawford Kazuo InamoriEdward E. David, Jr. Gerald D. LaubachJohn Diebold John D. MacomberJames D. Ebert Richard A. MeserveW. Gary Ernst Frank PressSandra M. Faber William J. RutterBruce W. Ferguson David E SwensenMichael E. Gellert Charles HL TownesRobert G. Goelet Sidney J. Weinberg, Jr.David Greenewalt

TRUSTEES EMERITICaryl P. Haskins

William R. HewlettWilliam McChesney Martin, Jr.

Richard S. PerkinsRobert C. Seamans, Jr.

Frank Stanton

YHAR Fk vi; ^5 • C

• Former Presidents and Trustees •

PRESIDENTS

Daniel Coit Gilman, 1902-1904Robert S. Woodward, 1904-1920John C. Merriam, 1921-1938Vannevar Bush, 1939-1955Caryl P. Haskins, 1956-1971Philip H. Abelson, 1971-1978James D. Ebert, 1978-1987Edward E. David, Jr. (Acting

President, 1987-1988)

TRUSTEES

Alexander Aggasiz, 1904-1905Robert O. Anderson, 1976-1983Lord Ashby of Brandon, 1967-

1974J. Paul Austin, 1976-1978George G. Baldwin, 1925-1927Thomas Barbour, 1934-1946James F. Bell, 1935-1961John S. Billings, 1902-1913Robert Woods Bliss, 1936-1962Amory H. Bradford, 1959-1972Lindsay Bradford, 1940-1958Omar N. Bradley, 1948-1969Lewis M. Branscomb, 1973-1990Robert S. Brookings, 1910-1929James E. Burke, 1989-1993Vannevar Bush, 1958-1971John L. Cadwalader, 1903-1914William W. Campbell, 1929-1938John J. Carty, 1916-1932Whitefoord R. Cole, 1925-1934John T. Connor, 1975-1980Frederic A. Delano, 1927-1949Cleveland H. Dodge, 1903-1923William E. Dodge, 1902-1903Gerald M. Edelman, 1980-1987Charles P. Fenner, 1914-1924Michael Ference, Jr., 1968-1980Homer L. Ferguson, 1927-1952Simon Flexner, 1910-1914W. Cameron Forbes, 1920-1955James Forrestal, 1948-1949William N. Frew, 1902-1915Lyman J. Gage. 1902-1912Walter S. Giftbrd. 1931-1966Carl J. Gilbert, 1962-1983Cass Gilbert, 1924-1934

Frederick H. Gillett, 1924-1935Daniel C. Gilman, 1902-1908HannaH. Gray, 1974-1978Crawford H. Greenewalt, 1952-

1984William C. Greenough, 1975-

1989Patrick E. Haggerty, 1974-1975John Hay, 1902-1905Barklie McKee Henry, 1949-1966Myron T. Herrick, 1915-1929Abram S. Hewitt, 1902-1903Henry L. Higginson, 1902-1919Ethan A. Hitchcock, 1902-1909Henry Hitchcock, 1902Herbert Hoover, 1920-1949William Wirt Howe, 1903-1909Charles L. Hutchinson, 1902-

1904Walter A. Jessup, 1938-1944Frank B. Jewett, 1933-1949George F. Jewett, Jr., 1983-1987Antonia Ax:son Johnson, 1980-

1994William F. Kieschnick, 1985-1991Samuel P. Langley, 1904-1906Kenneth G. Langone, 1993-1994Ernest O. Lawrence, 1944-1958Charles A. Lindbergh, 1934-1939William Lindsay, 1902-1909Henry Cabot Lodge, 1914-1924Alfred L. Loomis, 1934-1973Robert A. Lovett, 1948-1971SethLow, 1902-1916Wayne MacVeagh, 1902-1907Keith S. McHugh, 1950-1974Andrew W. Mellon, 1924-1937JohnC. Merriam, 1921-1938J. lrwin Miller, 1988-1991Margaret Carnegie Miller, 1955—

1967Roswell Miller, 1933-1955Darius O. Mills, 1902-1909S. Weir Mitchell, 1902-1914Andrew J. Montague, 1907-1935Henry S. Morgan, 1936-1978William W. Morrow, 1902-1929Seeley G. Mudd, 1940-1968Franklin D. Murphy, 1978-1985William I. Myers, 1948-1976Garrison Norton, 1960-1974

Paul F. Oreffice, 1988-1993William Church Osborn, 1927-

1934Walter H. Page, 1971-1979James Parmelee, 1917-1931William Barclay Parsons, 1907-

1932Stewart Paton, 1916-1942Robert N. Pennoyer, 1968-1989George W. Pepper, 1914-1919John J. Pershing, 1930-1943Henning W. Prentis, Jr., 1942-

1959Henry S. Pritchett, 1906-1936Gordon S. Rentschler, 1946-1948Sally K. Ride, 1989-1994David Rockefeller, 1952-1956ElihuRoot, 1902-1937ElihuRoot, Jr., 1937-1967Julius Rosenwald, 1929-1931William M. Roth, 1968-1979William W. Rubey, 1962-1974Martin A. Ryerson,-1908-1928Howard A. Schneiderman, 1988-

1990Henry R. Shepley, 1937-1962Theobald Smith, 1914-1934JohnC. Spooner, 1902-1907William Benson Storey, 1924-

1939Richard P. Strong, 1934-1948Charles P. Taft, 1936-1975William H. Taft, 1906-1915William S. Thayer, 1929-1932JuanT. Trippe, 1944-1981James W. Wadsworth, 1932-1952Charles D. Walcott, 1902-1927Frederic C. Walcott, 1931-1948Henry P. Walcott, 1910-1924Lewis H. Weed, 1935-1952William H. Welch, 1906-1934Gunnar Wessman, 1984-1987Andrew D. White, 1902-1916Edward D. White, 1902-1903Henry White, 1913-1927James N. White, 1956-1979George W. Wickersham, 1909-

1936Robert E. Wilson, 1953-1964Robert S. Woodward, 1905-1924Carroll D. Wright, 1902-1908

(: \: M , ni I w i n •:;<, \ • YEAR BOOK 95

Department of Terrestrial Magnetism staff member Erik Hauri and visitor Vincent Salters from Florida StateUniversity with the Cameca IMS 6f ion microprobe at DTM. The instrument, which enables researchers toexamine micro-scale variations in trace elements and isotopes by bombarding samples with beams of chargedparticles, is run as a regional facility, with approximately half the operating time reserved for scientists fromother institutions. It was formally dedicated in June 1996. (Photo by Steve Shirey)

• V!

These are times of growing apprehension about how deeply the

United States and several European countries are committed to the

support of scientific research. Because the Carnegie Institution of

Washington depends largely on an endowment for its annual operating funds, we

feel less threatened by diminishing federal grants than other institutions. This

circumstance is the consequence of decisions made decades ago by our trustees to

eschew expansion on the basis of "soft" money. In exchange for our scientific

independence, we have been somewhat limited in the scope and size of our

research efforts. Consequently, our scientists have more freedom than many others

to pursue long-term projects and

risky new directions.

We see our own earth filled n ., , . . ,* Besides being more indepen-

with abundance, hut we forget . , ^dent in research, Carnegie scien-

to consider how much of that1 1 * * i tists are relatively free from the

abundance is owing to thescientific knowledge the vast a cademic r e sP^ s ib l l i t i e s t h a t

machinery of the universe has b u r d e n the i r Peers in research

unfolded* universities. They have no formalrequirements for teaching. The

Thomas PaineThe Age of Reason, Part I substantial time and effort they

1794*. _ _ _ _ ^ ^ invest in graduate students and

postdoctoral fellows rather reflect

their recognition that teaching and research are interdependent endeavors.

Committee work at Carnegie is generally rare and short-lived, unlike the time-

consuming institutional committees that university faculty experience.

These considerations suggest an idyllic world in which Carnegie staff scientists

can devote themselves entirely to thinking important thoughts and doing ground-

breaking experiments. If there are any ivory towers left in the world, it would seem

that Carnegie must be one of them. But it is not and it cannot be. There is no way

in the contemporary world for an institution to be an ivory tower and maintain

scientific excellence and leadership. Like all research institutions, Carnegie has a

complex web of interactions with the larger scientific community and the public.*I am grateful to Timothy Ferris, whose essay "A Message from Mars," in the New Yorker magarine,August 19, 1996, p. 4» introduced me to Paine's writing about science.

Yi \h ft vk US • i; \ i v wt h - r j i,

Institutional Review Mechanisms

Consider, for example, the mechanisms by which the Institution obtains peeropinions of its research. A department director reviews the work of each staffmember every five years, with the help of evaluations from scientists outside theInstitution. Similarly, the president evaluates the department directors' scientificand administrative activities every five years; opinions are sought from departmentmembers as well as external reviewers. In both cases, the results are shared, on aconfidential basis, with the individuals being reviewed. In addition, each depart-ment is assessed by an Institution visiting committee approximately every threeyears; the committee members include experts from other institutions as well asseveral Carnegietrustees.

Typically, a visitingcommittee spends twodays at a department,and the members haveconversations with thepresident and directoras well as the staffmembers and postdoc-toral fellows. Thecommittee can chooseto address any topic,including excellenceand originality ofresearch, productivity,satisfaction among the staff and fellows, and adequacy of the facilities and re-sources. The visiting committees* reports are distributed to the trustees and thedirector, who may then share the evaluation with staff members. Beginning in1996, the Board of Trustees' newly established Research Committee will reviewthe available visiting committee reports each December. In addition, the newlyexpanded responsibilities of the Board's Employee Affairs Committee (previouslythe Employee Benefits Committee) include discussion of the visiting committees'comments on personnel matters, including salaries and benefits.*

Yet another opportunity to measure Carnegie science by external standards isprovided by the formal systems that evaluate and rank federal grant applications-Federal grants account for about thirty percent of our annual operating budget andarc critical for the success or particular projects; they provide support for materials,travel, publications, stipends for postdoctoral fellows, and, in the shape of "indirectvo^ts," funds for the infrastructure expenses associated with the related research.

Trustee Gary Ernst (left) and other members of the Visiting Committee tothe Geophysical Laboratory met with postdoctoral and predoctoral fellowsin February 19%.

tjjf R-.tfJ .if TriMteh ui i f j several other chanuc* to the Institutions Bylaws,,m»l its committees will funaiun. The rvviu'd R\law> require two regular meetv tnJ I \ u'niK't F«T .i fill) Jisiuvih*n, <t? f\ti?e 151

None of these evaluation methods is perfect. Scientists, and even trustees, bringsome biases to the processes. External experts are often longtime colleagues of thescientists being reviewed and may be loathe to be completely honest in theirappraisals. Competition, academic politics, and even petty jealousies can influencethe opinion of review panels. But together, the several approaches afford a reason-ably reliable appraisal of Carnegie research.

The Community of Science

There are other important ways in which Carnegie scientists interact with thebroader scientific community, and they provide compelling reasons why scientificresearch and an ivory tower mentality are no longer compatible. Foremost amongthem is the need for communication. The pace of research dictates that scientistsbe in constant touch with colleagues worldwide. Communication is provided atscientific meetings, and by Fax, phone, and email. The scientist who chooses notto be part of the "grapevine" runs a big risk of being left behind, or of missing somedevelopment that might advance a particular research project. Thus, it is not nowpossible, except in extraordinary circumstances, to do research in isolation and stillbe at the forefront of new knowledge.

The disappearance of the mirage of the ivory tower is, perhaps, most forcefullyevident in the tremendous communal effort, often unseen by the public, that fuelsand sustains the research enterprise. This effort consists of an active infrastructureof committees, commissions, workshops, and so on. It is based in institutions, inscientific societies, and in the federal government, and it works in both officialand informal ways. Through it, the scientific community strives for excellence,establishes research priorities, influences the expenditure and distribution offederal and private funds, and dictates access to major public facilities like theHubble Space Telescope. It becomes more vital and more complex as limitedresources require that institutions share major, unique, and expensive instruments.Any institution whose scientists fail to participate stands a good chance of becom-ing marginal, no matter how good its own resources and research. This means thatcitizenship in the scientific community is an ongoing and ever increasing responsi-bility. It demands time, study, writing, and extensive travel. It requires the nonsci-entific skills of negotiation and diplomacy. It also holds rewards. It ensures that theviews of individual scientists and their institutions are heard. And for the indi-viduals who participate, it avails important contacts and a degree of prestige.Rarely are there financial incentives for individuals and institutions in theseefforts. Indeed, it is more likely that there will be extra costs either for the scientistor for her or his home institution. Such costs are willingly assumed as part ofregular operations, given the importance of the effort. But it is worth noting thatthe expenditures are not recognized as "cost-sharing*' in the formulas that federalagencies use to determine institutional contributions to research grants.

The only way to convey the full sweep of Carnegie participation in this broadscientific infrastructure is to describe individual efforts. A full accounting makes

DTM's Alan Boss (right) at the 58thMeteoritical Society Meeting in Sep-tember 1995.

for an informative but rather boring catalog, and therefore what follows is a very

selective summary.

Participation in Scientific Societies

Scientific societies play a major role in the publi-cation of scientific journals. The societies' publica-tion committees set policy for their publications andeditorial boards. The boards are then responsible forthe review of submitted papers and decisions regard-ing publication. At stake are the integrity of thepublished body of scientific knowledge and thereputations and careers of the contributing scientists.Even the direction of research in particular subfieldsis strongly influenced by the interests and tastes ofeditors. Thus, editorial board membership is a seriousundertaking and can involve many hours of workeach week.

David James and Steve Shirey at the Department of Terrestrial Magnetism(DTM) have assumed such responsibilities for the Journal of Geophysical Research

and Geochemkal News, respectively. At the Geophysical Laboratory, Ron Cohenand Marilyn Fogel serve as editors of American Mineralogist and Ancient

Biomokcuks, respectively. Arthur Grossman at the Department of Plant Biology isan editor of the Journal of Biological Chemistry, and Chris Field is a senior editor ofGlobal Change Biobgy.

Besides the journals that publish individual reports of new research, there aremany review journals where experts annually survey entire fields. One importantseries of reviews is published by Annual Reviews, Inc., an organization startedyears ago by scientists. Winslow Briggs, director emeritus of Plant Biology, is onthe board of directors of this organization after serving for many years as an editorof the Annual Review of Plant Physiology and Mokcuhr Biology. This position is nowheld by the Department's current director, Christopher Somerville. Somerville isalso an editor of several primary journals in plant biology and, interestingly, is amember of the Electronic Publishing Committee of the American Society of PlantPhysiologists. George Wetherill, director emeritus of DTM, is an editor of theAnnual Review of Earth and Planetary Sciences, while DTM's current director, SeanSolomon, serves on the editorial committee that plans the yearly content for thesevolumes.

Joseph Gall at the Department of Embryology has what must be the mostpleasurable of the editorial positions. He is the Art and History Editor of MolecularBiiil(i0 of the Cell Each nionth he chooses an historically important illustration forthe cover of the journal, and he writes a brief, erudite, and usually charming essaytt) explain the picture.

Scientific societies also organize scientific meetings on local, national, and

• Yi'\K

international scales. Society members are engaged in a variety of related activities.They choose appropriate meeting sites, plan programs, invite speakers, and act ashosts for distinguished participants. Alan Boss at DTM has served over the pastfew years on committees organizing conferences on subjects ranging from Stardustto protoplanetary disks to the origin of the solar system.

Of course, the societies themselves have governing structures that keep theiractivities going. Election to a society office is an honor, a sign of great recognition.It can also be a major burden, albeit for a limited term of office. This year, SeanSolomon has the honor and the challenge of the presidency of the AmericanGeophysical Union.

Doing for Others What We Ask Them to Do for Us

Just as we ask experts from other institutions to participate in visiting commit-tees to our departments, or to evaluate our staff members, so Carnegie scientistsreturn the favor. A small measure of such activities is apparent in Carnegie'sintellectual contributions to Harvard University. Carnegie staff scientists serve onvisiting committees in the Departments of Astronomy (DTM's Vera Rubin), Earthand Planetary Sciences (Solomon), Organismal and Environmental Biology(Briggs and Field), and in the Center for Astrophysics (The Observatories' WendyFreedman). Some visiting committees require long travel to, for example, Austra-lia (Somerville), Japan (Geophysical Lab's Charles Prewitt), Israel (Plant Biology'sJoseph Berry), and Taiwan (Geophysical Lab's Ho-kwang Mao). Other visitingcommittees, functioning as scientific advisory groups, may be established by pureresearch organizations (exemplified by my service to the Weizmann Institute ofScience in Israel), by corporate entities (Somerville's service to the MonsantoCompany), or by foundations (Somerville's service to the Noble Foundation).

Federal agencies and their offshoots spend billions of dollars on research eachyear. Much of this money is given out to research institutions, like Carnegie, inthe form of grants and contracts for specific, investigator-initiated research propos-als. The peer-review process used by most agencies involves hundreds of commit-tees and thousands of scientists, Carnegie people among them. Federal agenciesalso use committees to advise them on future initiatives. The Associated Universi-ties for Research in Astronomy (AURA), which runs the Hubble Space Telescope(HST) for NASA, also advises the National Science Foundation (NSF) on theNational Observatories at Cerro Tololo, Chile, and Kitt Peak, Arizona, and on theGemini Project, where two eight-meter national telescopes are planned, one inChile, the other in Hawaii. Vera Rubin serves on the AURA board, and theObservatories' Alan Dressier serves on the Gemini board. Dressier and WendyFreedman recently completed work on an AURA committee called HST andBeyond, which was asked to consider the next generation of space telescopes.Dressier chaired this very important committee and served as editor of its pub-lished report.

There are also individuals who initiate efforts to fill a perceived need.

YEAR BOOK 95 • CARNEGIE INSTITUTION* 7

Embryology's Don Brown, who has served on the governing council of the Na-tional Academy of Sciences and has been president of the American Society forCell Biology, founded, years ago, the Life Sciences Research Foundation (LSRF).He is still its guiding spirit. The LSRF solicits fellowship support from science-based industry and then dispenses the postdoctoral fellowships to worthy candi-dates chosen in a highly rigorous and competitive process. Over the years, theLSRF has supported some of the brightest young people in the life sciences.

Research Consortia

In today's world, major research facilities are frequently operated by consortia ofinstitutions, including the federal agencies that provide essential funds. Theseconsortia plan and develop instrumentation and review applications for access tothe facilities. The Hubble Space Telescope is an important example; Carnegieastronomers from the Observatories and DTM are active participants in decisionsabout HST access. Paul Silver and Sean Solomon contribute efforts to IRIS(Incorporated Research Institutions for Seismology), which makes seismic instru-ments available for a variety of projects. Charles Prewitt has taken a leading rolein helping the earth science community access synchrotron radiation sources, inparticular, the new Advanced Photon Source at the Argonne National Laboratory.And Prewitt along with Ho-kwang Mao and Russell Hemley spend substantialtime with their Princeton and Stony Brook colleagues in planning and managingthe NSF-sponsored Center for High Pressure Research. At DTM, Erik Haurimanages access to the department's new ion microprobe. And, not the least, thevitality and accessibility of the data banks for the genomes of the fruit fly Drasophila and the experimental plant Arabidopsis thaliana owe a great deal to thededication of Allan Spradling (Department of Embryology) and ChristopherSomerville, respectively.

During the past year, Harvard University, the Massachusetts Institute of Tech-nology, and the University of Michigan joined Carnegie and the University ofArizona in the Magellan Telescope Project. Consequently, there will be not onebut two 6.5-meter telescopes at our Las Campanas Observatory in Chile. Thisexpanded consortium must work out agreements for construction and operation ofthe telescopes in a way that satisfies the scientific and administrative interests ofall the institutions, a formidable task. Leonard Searle, who stepped down as theCrawford H. Greenewalt Director of the Observatories early in 1996 just as thecommitments were received from the three new consortium members, worked hardat ensuring the success of this exciting development. Carnegie was very fortunateto recruit Professor Augustus (Gus) Oemler away from Yale to replace Searle inthis distinguished Chair. Besides his outstanding accomplishments in astronomicalresearch, Oemler is experienced in the negotiation of telescope consortia agree-ments, a skill he began immediately to apply to the challenge of the MagellanProject.

• YEAR ft OK 95

Observations

I hope this catalog has conveyed the sheer magnitude of the contributions tothe scientific enterprise made by Carnegie scientists over and above their highlyproductive research. Even more important, it should convey some sense of what itis like to be a scientist in a nation with a vast, vital, and exciting scientific enter-prise. Consider, for example, just one person—Christopher Somerville, director ofthe Department of Plant Biology. His name recurs frequently in this essay notbecause he does so many more things than anyone else, but to emphasize what allthis activity means on a personal level. He,like everyone else, reviews other people'sgrant applications, referees other people'spapers, and writes evaluation letters forproposed appointment and promotions inother institutions; he says that he generallyreviews one grant application or manu-script, or writes an evaluation letter, everyday, and his estimate (and mine) is thateach such task requires, on average, twohours. He frequently talks to colleagues allover the world, he organizes meetings,writes research papers and books, plans forbroad access to accumulating data, consid-ers the future directions for his field, talkswith the postdoctoral fellows in his lab,worries about appointments, facilities, andinstruments in his department, answers therequests of the president and trustees, and,of course, thinks about, plans, and carriesout experiments. He even found time this year to contribute his "way cool science"to Bill Nye the Science Guy's children's television program. A day in the life of ascientist in this last decade of the century requires stamina and dedication. Yetmost of us cannot imagine a more wonderful existence; the lure of new knowledgeis what carries the day.

The ramifications of the scientific enterprise are rarely evident to the largercommunity. The general public sometimes expresses a sense that the scientificcommunity is disconnected from the nation and its goals and aspirations. Inreality, the scientific infrastructure is a critical aspect of the nation's well-being.Carnegie scientists are not unique in their commitment to this effort; a similarstory could be told about every significant research institution in the country. Thescientific enterprise, like all important human endeavors, is a complex mix ofpersonal interest, individual curiosity, and dedication to the general welfare.

Plant Biology director Chris SomerviSIe andformer postdoctoral associate ChristianeNawrath examine Arabidopsis plants.

YEAR B X I 9s) • C \ R \ K ^ INMIII-IV-N

Jerome A. Kristian(1933-1996)

Cyril Grivet(1947-1996)

Winstow Briggs(retfred)

^Losses •

We are saddened to report the loss of Jerry Kristian, a staffmember of the Carnegie Observatories since 1968 (and a

fellow, 1966-1968). Jerry died when his small plane crashed intothe Santa Clara River on June 22, 1996. Trained as a theoreticianin astrophysics at the University of Chicago (Ph.D., 1963), hebecame an accomplished observer during his tenure at Carnegie.His work focused on quasar identifications, pulsar timing, gravita-tional lenses, galaxy imaging at remote look-back times, and theform of the Hubble diagram for the expansion of the universe.Personally, he was a source of quiet inspiration to the staff, givinghelp to all who asked. He will be sorely missed.

We will also miss Cyril Grivet, a technician at the Departmentof Plant Biology for nine years, who died July 17 when the TWAflight 800 he boarded in New York crashed in the ocean nearby.Holding two master's degree and a doctorate (all from Stanford),Cyril was a master technician in Joe Berry's lab, helping Joe solveintricate math problems to simulate global change.

Oscar Torreson, a DTM staff member from 1923 until 1951,died on December 15, 1995, at the age of 97. He served in avariety of capacities, working at the magnetic observatories inAustralia and Peru, and on the Carnegie research vessel asnavigator and executive officer.

George Tunell, Jr., a staff member at the Geophysical Labora-tory from 1924 until 1945, died on July 4, 1996, at the age of 96.Tunell came to Carnegie after receiving his doctorate in geologyat Harvard. Among his honors was the Mineralogical Society'sRoebling Medal in 1973.

Mack Ferguson, custodian and mechanics helper at the GL(1948-1981), died November 25, 1996.

William Quails, custodian/chauffeur at the Observatories(1978-1986), died November 3, 1995.

Carl Rinehart, instrument maker at DTM from 1964 until hisretirement in 1982, died March 21, 1996.

Bessie Smith, laboratory helper at the Department of Embryol-ogy (1965-1979), died October 28, 1996.

Felice Woodworth* draffsperson at the Observatories {1965-1978), died April H, 1996.

\C r< n~\ •

Retiring. • •

Three longtime Carnegie scientists retired on June 30, 1996:Winslow Briggs, Leonard Searle, and Francis R. Boyd.

Winslow Briggs served as director of the Department of PlantBiology from 1973 until 1993, at which time he stepped down toresume research full time. He plans to continue his research programin photomorphogenesis as a scientific consultant.

Leonard Searle has spent 28 years at Carnegie, serving as Obser-vatories' director from 1990 until June 1996. His research interestsinclude Galactic nuclei and stellar content, Galactic chemicalcomposition, and the evolution of galaxies. He will maintain hisoffice at the Observatories as a staff member emeritus.

Francis R. (Joe) Boyd, a staff member for 43 years, also plans tocontinue his research at Carnegie, as a consultant. His interestsinclude the composition and history of the Earth's upper mantle,xenoliths of mantle rocks, and high-pressure and high-temperaturephase studies.

Ray Bowers, the Institution's editor and publications officer,retired May 31, 1996, after nineteen years of service.

• Qains •

We welcome new staff members Yingwei Fei and Yixian Zheng.Yingwei Fei became a staff member at the Geophysical

Laboratory on July 1, 1996. He grew up in China and received hisPh.D. in 1989 from City University of New York. He was a predoc-toral and then associate staff member at the Laboratory and NSFCenter for High Pressure Research, 1988—1996. Among his interestsare element partitioning and phase relations in systems related to theEarth's interior, and physical properties of mantle/core material.

Yixian Zheng joined the Department of Embryology in September1996. She received her B.S. in biology from Sichuan University,China, and her Ph.D. (1992) in molecular biology from Ohio StateUniversity. Before coming to Carnegie, she was a postdoctoral fellowat the University of California, San Francisco (1992-1996). Herinterests include the arrangement and reorganization of cellularinteriors and the control of microtubule nucleation.

Patricia Knesek (Ph.D., University of Massachusetts) joined theLas Campanas Observatory as a resident scientist in October 1995.She studies the morphology, content, and evolution of galaxies.

Patricia Craig was appointed editor and publications officer inJune 1996.

Joe Boyd(retired)

Ray Bowers(retired)

New staff memberYixian Zheng

New staff memberYingwei Fei

YEAR Ek\>K ^5 • CARNEGIE INTUITION 11

Staff member AlanDressier

r*S

Director Christopher

Somervillc

Director

e^n Solomon

• Honors •

National and International Awards and Honors

The Observatories' Alan Dressier and Plant Biology director

Christopher Somerville were elected to the National Academy of

Sciences in April 1996.

DTM director Sean Solomon was elected a fellow of the Ameri^

can Association for the Advancement of Science in September

1995.

Joseph Gall of the Department of Embryology was selected toreceive a 1996 AAAS Mentor Lifetime Achievement Award.

DTM's Vera Rubin was elected to the National Science Board byPresident Clinton in July 1996. Rubin was also appointed to thePontifical Academy of Sciences in October 1996.

Geophysical Laboratory's Ho-kwang Mao was elected a foreignmember of the Chinese Academy of Science in June 1996.

Professional Society Awards

Vera Rubin received the Gold Medal of the Royal Astronomical

Society (London) during the Society's November 1996 meeting.

Donald Brown was selected to receive the 1996 E. B. Wilson

Award from the American Society for Cell Biology.

Former DTM staff member Albrecht Hofmann received the V. M.

Goldschmidt Award of the Geochemical Society.

The Geophysical Laboratory's Ho-kwang Mao was selected as a1996 Geochemistry Fellow of the Geochemical Society and theEuropean Association for Geochemistry,

Former DTM and Geophysical Lab staff members Ikuo Kushiro,George Tilton, Stanley Hart, and former DTM fellow WilliamWhite were also named Geochemistry Fellows.

Geophysical Lab postdoctoral fellow Tahar Hammouda wasawarded the Prix Lacroix from the Societe Frangaise de Mineralogieet Cristallographie for his Ph.D. thesis.

Geophysical Lab postdoctoral fellow Pamela Conrad received theAward for Outstanding Student Paper in the Tectonophysics Sectionof the American Geophysical Union at AGU s 1995 Decembermeeting.

.a K-TIT : • Yi \n pk 95

Foundation Awards

Embryology staff member Chen-Ming Fan received a John MerckFund Scholarship.

The Geophysical Lab's Larry Finger received a Humboldt Awardfor U.S. Scientists, presented by the Alexander von HumboldtFoundation, Bonn, Germany.

Academic and Institution Awards and Lectureships

Carnegie president Maxine Singer received an honorary degreefrom the Weizmann Institute of Science in November 1995. OnOctober 26, 1995, she was honored by the Washington Committeefor the Weizmann Institute at the Weizmann Founder's Day Event inhonor of her longtime service. She received the Mendel Medal atVillanova University on November 20, 1995.

Vera Rubin was awarded the 1996 Weizmann Women & ScienceAward on June 5 by the American Committee for the WeizmannInstitute of Science. She was elected to the first group of Fellows ofthe Association for Women in Science. She delivered the com-mencement address to physics and astronomy graduates at theUniversity of California, Berkeley, on May 17, 1996.

Sean Solomon delivered the annual S. Thomas Crough MemorialLecture at Purdue University in April 1996.

Russell Hemley and Ho-kwang Mao of the Geophysical Labora-tory were coauthors of a paper, "Vibron excitations in solid hydro-gen: a generalized binary random alloy problem" (Phys. Rev. Lett.74), that won an Alan Berman Award from the Naval ResearchLaboratory. Visiting investigators J. H. Eggert (Pomona College) andJoseph Feldman (NRL) were also coauthors.

Embryology director Allan Spradling delivered the Larry SandierMemorial Lecture at the University of Washington on May 6, 1996.

Alan Dressier was the Grubb Parsons Lecturer at the Universityof Durham, U.K.

Robert Hazen of the Geophysical Lab was the 1996 DibnerLecturer at the Smithsonian Institution.

Embryology research assistant Tammy Wu and predoctoral fellowJessica Blumstein won 1996 William D. McElroy Awards for Excel-lence in Undergraduate Research at Johns Hopkins University.Martha Kimos, a high-school laboratory7 helper at Embryology, wonthe Grand Prize at the 44th Annual Baltimore Science Fair for herproject mapping a zebrafish mutation.

Staff member

Donald Brown

Postdoctoral fellow

Tahar Hammouda

Postdoctoral fellow

Pamela Conrad

Staff member

Mat)

Yi \U ii ri i;. \

Research assistantTammy Wu

High school internAmanda Mart I

Trustee Philip Abelson

Geophysical Lab high school intern Amanda Mortl won the

Washington regional competition of the 1996 Junior Science and

Humanities Symposium, held in January 1996, at Georgetown

University. Her paper was about how the amino acid racemization of

ostrich eggshells can help scientists track the origins of modern

humans.

Allison Macfarlane, visiting investigator at DTM and the Geo-physical Lab from George Mason University, received a BuntingScience Fellowship and a John E Kennedy School Fellowship toexplore issues of high-level nuclear waste disposal during the 1996-1997 academic year at Harvard University.

And our trustees • • •

Philip Abelson received the Vannevar Bush Medal from theNational Science Foundation Board on May 8.

James Ebert was elected an honorary foreign member of theKorean Academy of Science and Technology on December 9, 1995,

Sandra Faber was appointed University Professor, the highesthonor the University of California bestows on its faculty.

William Golden received the 1996 Public Welfare Medal, thehighest honor awarded by the National Academy of Sciences, inApril 1996.

William Hewlett and David Packard jointly received the Com-puter Enterprise Award from the IEEE Computer Society on Decem-ber 7, 1995. Hewlett and his wife, Rosemary, received honoraryfellowships at Harris-Manchester College, Oxford University.

Frank Press received the Doctor Honoris Causa degree of theInstitut de Physique du Globe de Paris in June 1996.

William Rutter received the 1995 Heinz Award for Technologyand the Economy on November 20, 1995.

Trustee emeritus Robert Seamans, Jr. received the 1995 DanielGuggenheim Medal Award from the American Institute of Aeronau-tics and Astronautics on May 2, 1996.

Charles Townes received the 1996 Frederick Ives Medal, thehighest honor of the Optical Society of America, on October 22,1996.

• TOWARD TOMORROW'S DISCOVERIES •The Carnegie Institution has received gifts and grants from the following

individuals, foundations, corporations > and government agenciesduring the period from July 1,1995 to June 30, 1996.

FOUNDATIONS ANDCORPORATIONS

$100,00041 million

Ahmanson FoundationJohnson & JohnsonThe Fletcher Jones FoundationW. M. Keck FoundationThe G. Harold and Leila Y.

Mathers CharitableFoundation

Andrew W. Mellon FoundationJohn Merck FundAnihro.se Monell FoundationThe David and Lucile Packard

FoundationThe Ralph M. Parsons

FoundationThe Starr Foundation

$10,000^99,999

Abbott Laboratories FundAmerican Cancer SocietyCarnegie Corporation of New

YorkCarnegie Institution of CanadaJane Giffkt Chtkfe Memorial

Ftmd kw Medical ResearchCancer Research Fund of Darmwi

Runyan* Walter Wmchett

Freddie Mac FoundfarfcmFf^tpm McMitnm Inc.Fundacion AndesGokfcn Family FoutklatitmPhilip L. Graham FundWilliam Randolph Meant

ard Hughes MedicalLife Sciences RoH?#ri'h

Millipore FoundationMobil Foundation, Inc.Monsanto CompanyPew Scholars ProgramThe Thomas N. Urban, Jr. &

Mary Bright UrbanFoundation

Wallace Genetic Foundation,Inc.

Sidney J. Weinberg, Jr.Foundation

Helen Hay Whitney Foundation

$1,000 to $9,999

Amgen, Inc.Bristol-Myers Squibb CompanyRichard W. Higgins FoundationPaul and Annetta Himmelfarb

FoundationHuman Genome Sciences, Inc.George F. Jewett, Jr. 1965 TrustEli Lilly and Company

FoundationFreeport McMoran Inc.The Perkin-EImer Corporation

Under $1,000

Guven Clay Consultants, Inc.Keith Family Revocahle TrustPfeer Inc. Matching Gifts

Program

INDIVIDUALS

AmmymomMicHael E Oeflert

RtcharJ lt*m?Jbery frnwdmhrnMariah A»x.i;ttc% live.

Philip HL AhekmV. Elaine Bohon1 Bu«h

John DiehAJ

James and Alma EbertBruce W. FergusonW Kent Foid, Jr.Robert G. GoeletDavid GreenewaltRobert M. HazenRichard E. HeckertKazuo InamoriJohn D. MacomberBurton J. and Deedee McMurtryFrank PressGary QueenVera C. and Robert J. RubinDan and Maxine Singer

$1,000 to $9,999

L. Thomas and Margaret G.Aidrich

Louis and Lore E. BrownDonald D. and Linda W. BrownEdward E. David, Jr.Jo Ann EderSandra and Andrew FaberPembroke J. HartDaniel HeinzeWilliam R. HewlettThomas C. and Martha HoeringRobert JastrowPaul R KofailisGerald C LtubachMarlow V. MartsChester B. and Badbara C*

hi$ttktf Jr.Rlchaiti A. m& Martha A.

KlcserveGet>rge §C HimIkimli A. MsGeorge PutnamAlba SandageEugenia A. and Robert C

Seamtns, Jr.Allan SprawlingFrank SttmconDavid E Swensea

• Yi

Under $1,000

Jagannadham AkellaPaul A. Armond, jr.Toshi AsadaHenry A. and Claudine C. AtorHorace W. BabcockRalph B. BaldwinManuel N. BassBradley F. BennettWalter G. and Shirley A, BertGiuseppe and L. Elizabeth

BertaniHans A. BetheMontgomery S. and Joann

BradleyRobin BrettSteven J. BritzJeanette and Walter BrownGordon BurleyKenneth D. BurrhusDonald M. BurtWilliam BuscombeDana CarrollJames R CaseRobert M. CassieBritton ChanceRobin CiardulloWilliam X Coleman, Jr.John R. CroninHoward Clark DaltonPeter DavisIgor B. DawidJohn P, de NeufvilleVincent DeFeoJohn and Ruth DoakBruce R. DoeCharlotte and Gary ErnstAndrew FireDorothy Ruth FischerMichael and Helen FleischerKenneth A. and Ellen S. FolandArthur W GalstonSusanne E. GarveyKirsten and Oliver Gildersleeve,

Jr.Richard H. GoodwinWilbur H. and Mildred W. Go*Jt>seph S. GotsGilbert S. and Pola G.

Green waldRichard and Irene GrillHelen M. HabermannWilliam K. HartUlrich HeherJohn L Hedges

H. Lawrence HeiferAlfred D. HersheyJohn L, HessNorman and Katherine

HeydenburgSatoshl HoshinaHaifan Lin and Edna L HuKyoichi IshizakaEmilie JaegerDavid E. JamesPeggy A. and Mark E. KidwellDavid C. KooOlavi KouvoIkuo KushiroSteven W LHernaultOtto C. and Ruth LandmanArthur and Faith W. LaVelleHarold LeeTa-Yan LeongHarlan LewisCharles A. and Elizabeth LittleFelix J. LockmanEric LongWinston M. ManningMabel B. MattinglySheila McCormickSusan Gerbi'McIlwainSteven L. McKnightGisela MosigNorio MurataJack E. MyersT. S. OkadaHiromu OkadaJeffrey D. PalmerNeils M. PedersenGeorge PepperGeorge and Barbara PieperLelah Jean ProthroPhilippe ReymondGlenn C. RosenquistHelen RussellRuth N. SchairerPaul SchechterMaarten and Corrie SchmidtWilliam T. SchwessingerEdwin and Virginia ShookT. Jefferson SmithRobert S. and Jane S. SoluriDouglas K. StruckLinda L. StrykerMasatoshi TakeichiAlice I. and Kenneth K.

TakemotoLawrence A. TaylorGeorge R, Tikon

Elwood O. and Doris E. TitusScott B. TollefsenCharles H. TownesWilliam I. M. Turner, Jr.Mary Lee Morrison and William

B, UpholtJames Van AllenLarry N. VanderhoefFernando VolponiRichard J, WalkerZhou WangJames A. WeinmanMaurice WhittinghillKenzo YagiMasaru YamaguchiViolet Koski Young

U.S. GOVERNMENT

More than $1 million

U.S. Department of EnergyU.S. National Aeronautics and

Space AdministrationU.S. National Institutes of

HealthU.S. National Science

Foundation

$100,000 to $1 million

Space Telescope Science Institute

$10,000 to $99,999

National Institute for GlobalEnvironmental Change

U.S. Department of AgricultureU.S. National Institute of

Standards and TechnologyU.S. Office of Naval ResearchWestern Regional Center for the

National Institute for GlobalEnvironmental Change

OTHER

$10,000 to $99,999

Electric Power Research InstitutePotsdam-Institute for Climate

Impact Research PIKTexas Historical Commission

$1,000 to $9,999Dudley Observatory

YEAR RX^K 95 • CARNEUIE INSTITVTK N 17

X - "

V . ' . ' " V "•-,"

• , - ' r'_ / • I • " , . ' . % -

. "• i

~,;

i2&

V.

-

1f£1

• • ' " • . • • : . ; • • ;

. . . - - . . . , - "

• . • • ' • -

- • ' * ; * - •

1". •' '•Si'\

' - • ' • •

" • • • " . "

• - -

5

8^

• . ^ _ ' ~ - ;

•',- : ;'• ;*-3

IS

"• *""." "

*•" "

ii

ni tea at 813 Santa Barbara Street

Progress continues on the Magellan I telescope at Las Campanas. This photo, taken in August 1996. showsventilation louvers on the telescope enclosure. First light is expected in 1999. (Photo by Frank Perez.)

i' i v. j' Iw:* :\ x • YI\I l\k

Director's Introduction

This has been a landmark year for the Observatories. With the addition ofthree new members—Harvard University, the University of Michigan, andMIT—the Magellan Consortium is now complete, and the project to

construct two 6.5 meter telescopes on Las Campanas is a reality. Carnegie willhave a 50% share of the project, Harvard a 20% share, and the University ofArizona, the University of Michigan, and MIT will have about 10% each. This is avery happy combination of strong, like-minded astronomy programs, and we arelooking forward to the intellectual partnership with as much expectation as we areto the completion of the telescopes. The first Magellan Project telescope continuesto make good progress. As of this writing, the

enclosure nears completion at Las Campanas, and ---——•—--•••-—-—-———

the telescope mount is being assembled at L&F • • .JYOYltieTS Lie ITl

Industries. A year from now, the telescope should tTUXTty divectiotlSt the

be installed in the dome, awaiting only the arrival faitltest the TtlOStof the primary mirror. First light for Magellan I is distant, the earliest,anticipated in 1999, with Magellan II following , f1

about four years later. t h e SmttOest....

Completion of the Magellan Project shouldoccur very near the 100th anniversary of the founding of the Observatories. It willmark the end of a century of unsurpassed brilliance for an astronomical institution.Indeed, the history of 20th century astronomy was in large part written by Carn-egie Institution astronomers, and at Carnegie Institution telescopes. The challengebefore us is to make the Observatories' second century as brilliant as its first. Evenif we thought ourselves the equals of George Ellery Hale, Edwin Hubble, andWalter Baade, that would be a very daunting charge, because Hale's task, thoughno easier, was in many ways simpler than ours. George Ellery Hale stood at thedawn of modern astronomy and astrophysics, which he helped create. Before himlay limitless unanswered questions about the universe; all he had to do was buildthe biggest telescopes and find the best people to start using them.

Astronomy today is a much more mature field, and the practice of astronomy amuch larger enterprise. Entire areas*—stellar evolution, galactic structure—-havebeen developed, if not to completion, at least to the point of diminishing returns*Hordes of astronomers pursue the most fashionable and exciting topics; scarcely an

YK\u Bi\ *k 95 • CARN* tni INSTITI TU*N 21

intellectual niche is unfilled by at leasta few researchers. Great sums of moneyare spent by both government andprivate groups to build new facilities. In1926, there were 480 members of theAmerican Astronomical Society, ofwhom 30 worked at the Mount WilsonObservatory. Today, the AAS has 6500members, and still 30 work at theCarnegie Observatories. In such anenvironment it is much harder to towerover the field in the way that theMount Wilson Observatory did inHale's and Walter Adams times.

How, then, can the Observatoriesmake a contribution to the astronomyof the 21st century that is worthy of itshistory? Clearly, by the route that theCarnegie Institution has always fol-lowed: finding the great scientists andproviding them with the support theyneed to do great science. Thanks toMagellan, the Observatories will beable to provide its scientists with accessto telescopes which is second to none,in an environment for work which noother institution can even approach.What those scientists will be doing—working at the frontiers of our knowl-edge—is also clear, but where thosefrontiers will be is today totally obscure.Sometimes those frontiers movequickly. For example, there has been anexplosion in our knowledge of the earlyhistory of galaxies in the past few years.Sometimes they move painfully slowly.Hobble's program of determining thetwo fundamental cosmological

parameters is still incomplete. It is futilefor a scientific institution to try toohard to predict the important problemsof even the near future and direct itsefforts in those directions. The wisecourse is, rather, to find the mostnimble minds who will head for thefrontier wherever it may appear.

Those frontiers lie in many direc-tions: the faintest, the most distant, theearliest, the smallest. The two essayswhich follow describe two such direc-tions in which Carnegie astronomersnow work. Staff member PatrickMcCarthy studies high-redshift radiogalaxies. These galaxies are among themost distant in space, and thereforedistant in time, of any astronomicalobjects. They provide one of the mosteffective probes of the early formationhistory of galaxies. That history,completely unobserved a decade ago, isnow being vigorously explored with theHubble Space Telescope and the newgeneration of large ground-basedtelescopes of which Magellan will soonbe a member. Hubble Fellow JulianneDalcanton describes a subtler, and lessappreciated, frontier—that of detect-ability. The very-low-surface-brightnessgalaxies which she studies are justbarely visible above the night sky'sglow. Completely ignored until re-cently, they may represent an importantconstituent of the universe, and may,like radio galaxies, provide an impor-tant handle on the processes of galaxyformation.

—Augustus Oemler, Jr.

Crawford H. Greenewalt Chair

i , Vf. ,•! 3%-T i r Ih N • Yl Si. f>

The Sky at Meter Wavelengthsby Patrick]. McCarthy

Before the invention of electric lighting and all of the technological marvelsthat followed, gazing at the star-filled sky was one of our primary forms ofnighttime entertainment. Our eyes, however, give us a limited taste of the

wonders of the sky, as they are sensitive to only a thin slice of the electromagneticspectrum. (See Fig. 1.) If, for example, our eyes were sensitive to the far infrared(where wavelengths are roughly 100microns, or one tenth of a millime-ter), we would see the sky filled withclouds of dust with temperatures of200 degrees below zero centigrade.

Radio galaxies are powerfultools for probing the evolutionof the early universe* Patrick

McCarthy explores the uniquecharacteristics of these

giant objects.

Two bright bands would cut acrossthe sky, revealing disks of dust bothin the plane of the Milky Way and inthe solar system.

At the long-wavelength end of thespectrum, in the realm of radio astronomy, electromagnetic waves can be as long asa kilometer across. If our eyes were sensitive to radio waves (putting aside the factthat at these wavelengths our one-cm diameter eyes could not resolve even thelargest objects in the sky), the Sun would still be the brightest object in the sky.However, the daytime sky would be nearly as dark as the night sky The Milky Waywould cut a beautiful swath across the sky, but the light would come not from thestars but from synchrotron radiation, released as cosmic rays travel through themagnetic field of our Galaxy.

At radio wavelengths, we would see virtually no bright stars, but embedded inthe plane of the Milky Way would be shells of light with diameters many timesthat of the full Moon. These are the remnants of supernovae, stars in our Galaxy

Before becoming a staff member in 1993, PatrickMcCarthy was a Carnegie Fellow, then a Hobble Fellow, atthe Observatories. He received 'both his M.S.. and his Ph.D.(in astronomy) from the University of 'California atBerkeley. Concurrent with his interest in radio .astirofiomy*•he studies galaxy formation and evotucioxi*

i R* x K 95 • € w s£t in Is>!in

The Very Large Array Radio Telescope at the NationalRadio Astronomy Observatory, Socorro. New Mexico.Courtesy, NRAO.

that exploded hundreds or thousands ofyears ago. The radio sky contains manyother objects that appear unresolved atthe resolution of our eyes (which isabout one arc minute at visible wave-lengths). Most of these sources are radiogalaxies and quasars, which are some ofthe most intrinsically luminous objectsin the universe. Radio sources appearbright even though they are among themost distant objects known, lying asmuch as 15 billion light years away.This is in dramatic contrast to therelatively nearby (only a few tens ofthousands of light years distant) starsthat populate the visible sky. Radiostwrces span a much larger range of

intrinsic luminosity than either stars orvisible galaxies, so the lists of theapparently brightest radio sources alsocontain many of the intrinsically mostluminous sources at distances compa-rable to the dimensions of the universeitself.

Since many radio sources areextremely distant, they are particularlywell suited for studying how theuniverse has evolved over time. Inparticular, we can use radio sources toinfer the density and pressure of gaspresent in the neighborhood of verydistant, and hence young, galaxies. Forthe past few years, I and my colleaguesVijay Kapahi, director of the NationalCentre for Radio Astrophysics in India,and Eric Persson, Observatories' staffmember, have undertaken a large-scalecensus of the radio sky. Highlightedhere, our work illustrates the power ofradio astronomy to probe the evolutionof the early universe.

A Southern HemisphereRadio Survey

In 1988 we cataloged 543 radiosources above a well-defined brightnesslimit in a strip of sky that passes nearlyoverhead at Carnegie's Las CampanasObservatory in Chile. Because thepositions of our radio sources were notprecisely known, we then traveled tothe high planes of New Mexico, wherewe observed them with the NationalRadio Astronomy Observatory's Very7

Large Array. This is a telescope com-posed of 21 dishes whose combinedsignals are used to produce images witha resolution equal to that of a singletelescope with a diameter of roughly 30km. Finally, we went to Las Campanas

24 iv*iir:iir\ • YIAR

to use the du Pont Telescope, identify-ing at visible wavelengths each of theradio galaxies and quasars that were thesources of the radio emission detectedin our initial radio survey.

Before we could answer any astro-physical questions, we needed to knowthe distances to each radio source inour sample. Distance is determinedfrom the redshift and the Hubbleconstant, which is the quantity relatingthe distance of an object to its redshift.(The redshift is a measure of therecession velocity of an object.) Aredshift of 1, for example, means thatthe wavelengths of light have beenincreased by 100%, and corresponds toa distance of roughly half the size of theuniverse. A redshift of 2 corresponds to75% of the way back, while a redshift of1000 would probe the universe when itwas only 100,000 years old.

We measured the redshifts of manyof our objects using the spectrographson the 2.5-meter du Pont Telescope.The most distant radio galaxies in oursample are too faint for the du PontTelescope; these we measured with the4.0-meter telescope at Cerro Tololo,located 70 miles south of LasCampanas. Remarkably, more than50% of our 543 radio sources lie atdistances that are at least half wayacross the visible universe, and 8% liemore than 80% of the way.

The Evolution of RadioSource Sizes

Wavelengths in the radio portion ofthe spectrum range from millimeter tokilometer length. Most extragalacticradio astronomy is focused on theportion ranging from roughly 20millimeters to 3 meters, correspondingto frequencies from as large as 15,000MHz down to the top of the FM radioband at 100 MHz. The low-frequencyportions of this window are increasinglyimpacted by man-made sources ofinterference.

Although all galaxies emit someradio waves, most produce very few,emitting at radio frequencies only a tinyfraction of the total energy theirconstituent stars produce at visible andultraviolet wavelengths. Radio galaxies,on the other hand, are the smallfraction (roughly 1%) of large galaxiesthat radiate a large amount of theirtotal luminosity in the radio portion ofthe spectrum. The radio waves emittedby radio galaxies and quasars arise fromcharged particles, most likely electrons,moving through a magnetic field atspeeds very close to the speed of light.The magnetic field effectively puts thebrakes on these speeding electrons, andas they slow down they give up theirenergy as radio-wavelength photons.

Most radio galaxies and quasars eject

10- 10"2 1 102 10

figure I. Electromagnetic spectrum (wavelengths in meters).

Yl \¥

Figure 2: The angular sizesof radio sources from oursurvey. Each point is themedian size in seconds of arcfor 15-30 galaxies in theredshift range indicated bythe horizontal error bars.The vertical error bars showthe typical range of sizesfound at each redshift. Thecurves are the expectedangular size of a radio sourceof constant linear size in twodifferent cosmologies. Thesolid line corresponds to anempty universe; the dashedline is for a universe with justenough matter to eventuallyhalt, but not reverse, theexpansion (a criticaluniverse).

Redshift

their high-energy electrons in the formof streams, or jets, having high internalpressure. While we usually think of thespace between the stars as being empty,it actually contains gas with densities ofone or so atoms per cubic centimeter.The ionized gas, or plasma, that pro-duces radio emissions has an even lowerdensity, even though the pressure in theradio-emitting material is very high.

As the radio jets push on the gas inthe surrounding medium, they expandat speeds typically 5% of the speed oflight. Like a jet of high-pressure air ex-panding into a body of water, a radio jetcreates an interface between the nearlyevacuated region it defines and the*> unrounding medium. The size of theevacuated region tells one about boththe power of the jet and the density ofthe surrounding medium. The largestradio sources span nearly 10 millionhyht ye;*r», making them the largestindividual object* in the universe.

One of the simplest questions we can

ask about the evolution of radio sourcesis whether they were the same size inthe past as they are now. Figure 2 showsa plot of the apparent angular sizes (theangle they subtend from the Earth) ofradio sources in our survey. The plottedpoints are the median sizes at ninedifferent redshifts; each point containsdata for 15-30 objects. The superposedsmooth curves show the apparentangular size of an object of constantphysical size for two different modeluniverses. The solid line is for anempty, and hence open, universe (onewhich would expand forever), whilethe dotted line is the prediction for auniverse on the dividing line betweenopen and closed, with just enoughgravity to eventually halt, but notreverse, its expansion. (The curvesdeviate from the straight-line expecta-tion in a Euclidean universe becausethe curvature of space bends the lightfrom distant objects and magnifies thesesources, essentially acting like a lens).

J\«

As seen in Figure 2, for redshifts lessthan 2, which correspond to distancesbetween 8 and 12 billion light-years,the radio sources in our sample have aroughly constant physical size. Moredistant sources, those with redshiftsbeyond 2, show a marked decrease intheir angular sizes, suggesting that theyare physically smaller. We calculate thatthey are two and a half times smallerthan the radio sources at intermediateredshifts. Coupling this data with ourestimates of the power of the radio jetsleads us to conclude that the sources inthe early universe were smaller thanpresent-day radio galaxies because theywere born in higher-pressure environ-ments. Thus, complete samples ofsources, like ours, provide us with aprobe of the conditions in the universewhen it was only 10-20% its currentage.

Ultraviolet Emission FromRadio Sources

Radio galaxies and quasars producecopious amounts of ultraviolet radiation(wavelengths from 0.03 to 0.3 microns;see Fig. 1). This radiation is seendirectly in the quasars, which appear asunresolved points of light with colorsindicative of a strong ultravioletcomponent that does not arise fromstars. When first discovered, radiogalaxies appeared to be normal in allrespects (other than being roughly amillion times more luminous at radiofrequencies than the average galaxy isat visible wavelengths). However, inthe mid-1980s, large optical telescopeswith modern digital detectors obtainedthe first detailed images of radiogalaxies. The images revealed complex

structures unlike those seen in normalgalaxies. In 1987, my colleagues and Iat the University of California discov-ered that the spatially resolved ultravio-let light in radio galaxies is found onlyalong the pathway of the expandingradio jets. This so-called "alignmenteffect" is illustrated in Figure 3, whichshows images of the radio galaxy MRC0406-244, found in our survey. Theradio emission appears as contours ofconstant brightness; the ultravioletemission appears as a gray scale. Thecorrelation between the ultravioletcontinuum radiation (right panel) andthe light from glowing hydrogen gas(left panel) with regions of bright radioemission illustrates the alignmenteffect.

Although the alignment effect wasdiscovered nearly a decade ago, it stillremains largely unexplained. Twocompeting models exist. One hypoth-esizes that hot massive stars are formedby the passage of the high-pressure jetsthrough dense gas lying near galaxies inthe early universe. Thus, the ultravioletcontinuum seen along the radio jetswould reveal regions of stimulated starformation. The other theory postulatesthat radio galaxies harbor powerfulsources of ultraviolet light that areenshrouded by dust and are thus hiddenfrom Earth-bound observers. In thisway, clouds of ionized gas or dust thathover above the central source of theUV light would act like a mirror andreflect a small fraction of the lighttowards the Earth, producing theregions of ultraviolet light found alongthe radio jet's path. The high degree oflinear polarization (approximately10%) seen in several distant radiogalaxies lends strong support to this

YfcAK PkV>K 95 • C;\RM ul l IKMITI Ti. 'X 27

Figure 3: Two images of the radio galaxy MRC 0406-244. The right panel shows an image in the ultravioletcontinuum obtained with the Hubble Space Telescope. The left panel shows an image taken in the light ofionized hydrogen, obtained with the du Pont Telescope at Las Campanas. In both images, the radio emissioncorresponds to the contour lines, and the ultraviolet emission corresponds to the bright regions. These imageswere prepared by postdoctoral associate Brian Rush.

theory, since reflection naturallyproduces a high degree of polarization.

Recent improvements in near-infrared imaging detectors and therefurbishment of the Hubble SpaceTelescope offer new tools that we canapply to this problem. Together withObservatories' postdoctoral researchassociate Brian Rush, I have analyzeddeep Hubble Space Telescope images ofthe radio galaxy MRC 0406-244 in aneffort to understand the alignmenteffect. We are considering two possiblesources for the extended ultravioletemission: scattering of the UV light bydust grains, and scattering by freeelectrons (Thompson scattering).

The cloud of ionized gas associatedwith MRC 0406-244 is roughly 100,000light years across and contains a mass ofgas equivalent to 100 million Suns.While the cloud appears to be fairlysmooth and uniformly filled, it actuallycontains tens of billions of individual

clouds with densities of approximately100 atoms per cubic centimeter. Thegas in these clouds has a temperature of10,000 Kelvins, and the clouds areembedded in a very tenuous atmo-sphere with temperatures of from 10 to100 million K. This hot mediumconfines the dense clouds and preventsthem from dissipating on time scales ofa few million years.

The galaxy's central nucleus emitsroughly 1O55 far-ultraviolet photonseach second. These photons traveldistances of 50,000 to 100,000 lightyears along the path cleared in thewake of the radio jet, until they en-counter clouds of dense gas. When theydo, each photon ionizes a hydrogenatom within the cloud. Then, afterbeing absorbed and re-emitted severaltimes, it is transformed into a Ly-CXphoton with a wavelength of 0.1216microns, at which point it escapes thenebula. When the hydrogen gas is

Facing page: Patrick McCarthy (right) and postdoctoral associate Brian Rush al Santa Barbara Street.

YfcAK • C K - I I P

ionized, it releases electrons that canreflect, or scatter, a fraction of theincident ultraviolet light away from thenucleus and toward the Earth. Whetherthe electrons can reflect enough of it toproduce the observed luminosity of theUV light seen in the alignment effect isunclear. Calculating the reflectivepower of these electrons (which ispossible with a modest degree ofaccuracy, using the properties of theionized gas), Rush and I found that thereflectivity of the electron plasma inMRC 0406-244 ranges roughly 1-5% indifferent parts of the cloud. This iswithin a factor of three to five of theamount needed to explain the observedultraviolet continuum light.

Dust grains (roughly 1 micron indiameter) also reflect ultraviolet light,but they do so more effectively thanelectrons, being 10,000 times moreefficient per unit mass. If the dust inMRC 0406-244 makes up roughly 1/2%of the total mass of gas (as it approxi-mately does in dense clouds in our ownGalaxy), it would provide a reflectivityof roughly 30%, enough to produce theultraviolet light seen along the radiojets. However, the dust content ofdistant galaxies may not be the same asthat in the Milky Way. Distant galaxiesseen shadowed against bright quasars,for example, have dust contentssuppressed by a factor of ten or more.This leads us to believe that dustscattering in radio galaxies might notbe effective enough to produce theultraviolet emission we see.

Reflection by dust has a spectralsignature very different from reflectioncaused by electrons. Electrons reflectvisible and ultraviolet light equally,

while dust reflectivity depends onwavelength to the inverse fourth power,and hence is much more efficient in theultraviolet, where the wavelengths oflight are small compared to the size ofthe dust grains. Deep near-infraredobservations should help us resolve thisissue. If electrons are the scatteringmedium, near-infrared images shouldreveal structures similar to those seen inthe ultraviolet. If, on the other hand,dust is the scattering medium, thesignal in the near-infrared will beroughly 100 times fainter.

Unfortunately, our deepest imageswith the near-infrared camera on the duPont do not reach the sensitivity levelneeded to settle this issue. At themoment, we are unable to concludewith certainty whether electron or dustscattering is the dominant mechanism.The Magellan telescope, and the nextgeneration near-infrared instrument setto be deployed on the Hubble SpaceTelescope in early 1997, will be able todetect the signature of electron scatter-ing in the near-infrared unequivocally.

Radio surveys like ours, and similarprograms going on in the UK and TheNetherlands, have revealed to us apopulation of massive galaxies at largeredshifts. These giant radio sourcesdisplay a wealth of astrophysicalphenomena, many of which are notevident in our view of the local uni-verse. At the same time, they serve astools, allowing us to study the universewhen it was only 10-20% its currentage. As the Magellan telescopes andother large telescopes around the worldcome into operation, they will allow usunprecedented views of one of nature'sgrandest creations.

• Yf.AK 95

Lurking Qalaxieshy JulianneJ. Dalcanton

Anybody who has seen a science fiction movie or an astronomy special onpublic television has a reasonable idea of what a galaxy looks like. Thebackgrounds behind spaceships and the posters on undergraduate

dormitory walls are filled with pictures of huge swirling galaxies with stars tracingenormous arms spiraling out of the center of a thin disk of gas, dust, and multi-colored stars. The images of these galaxies are dramatic and compelling, but theyare also somewhat misleading.

Although we happen to live in thedisk of a spiral galaxy, these galaxies areby no means the norm. Perhaps morerepresentative of the population ofgalaxies in the universe are the two faintsmudges in the southern sky—the Smalland Large Magellanic Clouds. These twosmall galaxies are actually tiny compan-ions to our own large Milky Way. Whilethey are far from impressive, being almostfactors of 50 less massive than our owngalaxy and having diameters five timessmaller, the Magellanic Clouds are amonga sample of galaxies far more numerousthan the giant spirals and ellipticals which even astronomers refer to as normal.

The Magellanic Clouds show us something very fundamental about the uni-verse—that galaxies are formed at many different scales. There are giant galaxiesfactors of ten larger than our own, and there are tenuous, diffuse "dwarf' galaxies afactor of 100 smaller than the Magellanic Clouds. The Magellanic Clouds alsoshow us another important way in which galaxies are astoundingly diverse—in

It may be that galaxies oflow surface brightness,

often overlooked byastronomers, are the mostnumerous galaxies in theuniverse. Besides helping

explain some of theuniverse's missing mass,

they offer clues aboutgalaxy formation.

The Hubble Postdoctoral Fellowship is a prestigious,-nationwide award bestowed only to- a handful of indi-viduals each year. Juiianne Dal canton came to the'Observatories as a Hubble Fellow in 1995. She receivedtier B«S- from MIX artd her Ph.0« {in astrophysics) fromPrinceton University*

YEAR BOOK 95 • CARNEGIE INSTITUTION

their surface

brightness. TheLas CampanasObservatory isblessed with oneof the darkestskies in theworld, but whenyou go outside atnight and looktowards the sky,you can barelysee the Clouds.What the poetconsiders to bethe blackestvelvet of mid-night, the astronomer actually sees asannoyingly bright. For the atmosphereglows faintly even at night, far from thelights of any major city, with theemission of atoms and molecules farabove the surface of the planet. Againstthis bright background, the diffuse lightcreated by the stars in the Clouds is solow that it is difficult to see them withthe unaided eye. In fact, even the disksof bright galaxies like the Milky Wayare actually fainter than the night skyitself!

Finding low-contrast galaxies againstthe bright background of the night skyis a problem not just for the casualstargazer, but for the astronomer usingthe largest telescopes and the mostsensitive detectors. In the same waythat the Magellanic Clouds are close tothe limiting surface brightness the eyecan detect, there are galaxies whosesurface brightnesses are at the limit ofwhat a large telescope can detect. Thisraises a very interesting, though perhapsobvious, point: Astronomers can onlystudy the properties of galaxies which

The spiral galaxy NGC 2997, above, is what mostpeople think of as a "normal" galaxy. Far morenumerous, however, are galaxies like the SmallMagellanic Cloud, on facing page, whose surfacebrightness is orders of magnitude smaller. (Thediameter of the SMC is about ten times smaller thanNGC 2997.) Photos from the Carnegie Atlas ofGalaxies, by Allan Sandage and John Bedke.

fall above the limiting surface bright-ness of their observations.

A limit to the observable surfacebrightness can lead to strong buterroneous correlations in the propertiesof galaxies, which reflect more aboutthe way the observations are made thanabout the intrinsic nature of what isbeing studied. This problem, whichastronomers refer to as a "selectioneffect," can be illustrated by making ananalogy to a census of U.S. citizens.Suppose a naive polltaker questionedpeople who live only in Beverly Hills,and used the data to draw conclusionsabout the population of the UnitedStates as a whole. The polltaker woulderroneously find that most everyone inthe United States is incredibly wealthy.Likewise, an astronomer taking a censusof galaxy populations could conclude

I '\, • Yi w ft

that all galaxies have a characteristicsurface brightness suspiciously similar tothe limiting surface brightness. This, infact, happened in the early 1970s withthe "discovery" of Freeman's Law,which stated that all galaxy disks havea characteristic surface brightness.

Fortunately, since the 1970s therehas been a growing appreciation of therole that our biases against low-surface-brightness galaxies have played inshaping past knowledge of galaxypopulations. With this has come a driveto understand and quantify selectioneffects in existing censuses of galaxiesand, more importantly, to design new,less-biased galaxy surveys which willopen a window onto a wider view ofthe true galaxy population. Becausethere are possibly unknown galaxies asclose as our own Galactic backyardwith surface brightnesses so faint thatthey have never been seen, we have anextremely incomplete understanding ofthe universe. It is vital that we openour eyes onto this previously hiddenworld if we are ever to understand the

forces that shapegalaxies. Byattempting tomake sense of thephysics drivinggalaxy formationwithout completeknowledge of theentire galaxypopulation,astronomers areakin to unfortu-nate sociologistsusing the BeverlyHills census tobuild elaboratemodels explaining

why the United States is so prosperous.The last five years have seen a

particularly dramatic improvement inour understanding of the low-surface-brightness universe. Two new, largecatalogs of low-surface-brightnessgalaxies have appeared, one created byJames Schombert (NASA), GregBothun (University of Oregon), andDTM postdoctoral fellow StacyMcGaugh; the other by Chris Impey(University of Arizona), DavidSpray berry (University of Groningen,The Netherlands), and Mike Irwin(Institute of Astronomy, Cambridge).The new observations have surfacebrightness limits roughly a factor of tenfainter than the workhorse galacticcensuses on which most astronomerrely, and they have revealed a universeof unusual, diffuse galaxies. Smallersurveys, which push the limiting surfacebrightness another factor of ten lower,both in clusters (gravitationally boundcollections of galaxies) and in thesmoother background of galaxiesknown as the field, have also appeared.

Y? \r,

1 myself have done this latter survey,and I am currently collaborating withformer Carnegie fellow Dennis Zaritsky(now at the University of California,Santa Cruz) to expand it.

Several astronomers, including StacyMcGaugh, David Sprayberry, and me,have shown that this previously hiddenpopulation of low-surface-brightnessgalaxies is not a negligible dusting ofunimpressive galaxies sprinkledthroughout the skies, but is a veryimportant contributor to the universe.Low-surface-brightness galaxies may, infact, be the most numerous type of

galaxy in the universe. If all thesegalaxies were added together, the totalmass might well be as much as thecombined weight of all other previouslyknown galaxies. Current low-surface-brightness surveys are not quite suffi-cient to place tight numerical con-straints on the degree to which thesegalaxies contribute to the number andmass density of the universe. But theyhave already provided a crucial puzzlepiece for understanding the problem ofgalaxy formation. For they show us thatmany, if not most, galaxies have lowsurface brightness.

Despite their dramatically differentsurface brightness, low-surface-bright-ness galaxies have some surprisingsimilarities to normal galaxies. Like thedramatic high-surface-brightness spirals,they tend to be rotating disks of gas andstars, with a circularly symmetric lightprofile which fades exponentially fromthe center outwards. Even moresurprising, galaxies over the entirerange of surface brightness tend to sharethe same relationship between thespeed of their outer-disk rotation andthe brightness of their disk. While the

laws of physics suggest that the shape ofthe relationship should be the same forall galaxies regardless of their surfacebrightness, the only way for galaxies tofall on the exact same curve is if physicshad conspired to accompany anydecrease in the surface brightness of thedisk with a precise increase in theamount of mass encompassed by thedisk.

In addition to the broad similarities,there are also some systematic differ-ences (besides the obvious change insurface brightness). For example, thelow-surface-brightness galaxies tend tospin more slowly in their centers thantheir brighter counterparts, eventhough the two types spin equally fastin their outer regions. The disks of low-surface-brightness galaxies also tend tobe more spread out than those ofnormal galaxies.

This intriguing collection of differ-ences and similarities raises a veryinteresting question. How did natureproduce such a wide variety of galaxieswhile preserving so many similaritiesfrom galaxy to galaxy? I believe theanswer to this question can be found inthe process of galaxy formation. Whenthe universe was very young, space wasfilled with a mixture of hot gas and themysterious dark matter, which, al-though it has not been observeddirectly, can be inferred to exist fromthe motions of stars and gas. While thisearly cosmic soup was extremelysmooth, there were almost certainly thetiniest of ripples within it, so that someparts of the soup were denser thanothers, if only by the slightest amount.As the universe aged, the excess gravityin these overdense regions helped pullnearby matter into them, shaping the

H • Y* >\i ft

lumps into continuously denser andmore massive protogalaxies. Eventually,the hot gas in these protogalaxiesbecame dense enough to interact withitself, and began to cool and contracteven further inwards into the center ofthe protogalaxy. This collapse pro-ceeded until either all the gas wasturned into stars (which cannot cool),or some other physical process tookover and stopped the collapse.

During the formation of disk galax-ies, that other process is thought to bethe spin which the gas acquired while itwas still a young, puffy protogalaxy. Thelumps in the early universe were notalone, and they tugged on one anotheras they were forming. The smallgravitational nudges caused most of thelumps to begin whirling slightly. As thebarely rotating gas in the young galaxycooled and collapsed into the center ofa halo of dark matter, the gas spun evenfaster, speeding up like a person pullingin his or her arms while spinning in adesk chair. However, the gas can't fallall the way into the center, because itspins too fast.

Anyone who has been to an amuse-ment park knows the experience ofbeing thrown outwards by a rapidlyrotating ride. Galaxy disks experiencesimilar forces, except that gravity, notwalls or seatbelts, prevents the gas frombeing flung outwards. The gas settles toa place where the restraining force ofgravity exactly balances the flingingforce of the rotation. In a rapidlyrotating disk, the gas settles in to alarger radius than it would in a slowlyrotating disk. It does so because it needsa larger restraining force to hold ittogether. The gas's orbit encloses moreof the mass of the dark matter, which

provides more gravity to hold the gasin. Therefore, a rapidly spinningprotogalaxy will eventually form a verylarge disk, with the gas spread out overa larger area than in a disk which formsfrom a slowly spinning protogalaxy.

Stars are born from the gas only afterit settles into the disk, so if the gas isvery spread out, the stars which formfrom the gas will be spread out as wellAll the light we see from galaxies comesfrom the stars, so a rapidly spinninggalaxy, with its widely spread stars, willappear to have low surface brightness.(It will also encompass a wider areathan a slowly spinning galaxy of thesame mass.) Because the restrainingforce of gravity is vital in shaping thegalaxy, the shape and size of a disk alsodepends on how much mass is in it.Lower-mass galaxies thus form disks oflow surface brightness just as rapidrotation does, although the lower-massdisks are smaller.

My collaborators David Spergel andFrank Summers and I believe that thisgeneral picture leads naturally togalaxies with the range of properties wesee, while preserving the generalfeatures shared by all galaxy disks.Because the structure of a galaxy diskdepends upon both the mass and thespin of the protogalaxy from which itformed, any variation in the masses andspins of protogalaxies will automaticallyproduce wide variations in surfacebrightness and disk size. Astronomerscan calculate the expected distributionof both the masses and spins of primor-dial galaxies from theories of the originof the initial ripples in the cosmic soup.We have transformed these theoreticalexpectations into a prediction for theobservable properties of galaxies today,

Yt \P I\ VR 95 • CAKNJEI ;IE ISSIIXUIJON

Observatory domes dot the Las Campanas landscape when viewed from Mount ManQiii, the site of the futureMagellan telescopes. Left to right: the 1-meter Swope telescope, the University of Toronto's 24-inch telescope,the 10-inch astrograph, the 1.3-meter Warsaw telescope, and the 2.5-meter du Pont reflector.

and find that our calculations yield aremarkably good fit. They explain thelarge disks and the slow inner rotationof the low-surface-brightness galaxies,

and they explain the properties thesegalaxies share with normal galaxies,including the relationship betweenbrightness and rotation speed. Moreimportantly, for the first time we canexplain why galaxies form with anincredible range of sizes and surfacebrightnesses. We can even predictwhat we might see when we begin to

observe the universe at even lowersurface brightness.

It seems, from our calculations, thatwe truly have seen only the tip of theproverbial iceberg, and that there is awhole universe of lurking galaxieswaiting to be discovered and studied.We believe that the light hidden bythese low-Hirtace-hritfhtness galaxies

may be more than twice what we cancurrently detect. We also believe thatsome galaxies may be hiding forentirely different reasons; our calcula-tions suggest that many galaxies maybe so small that they are mistaken fornearby stars!

It seems clear that discoveries arewaiting for us in the hidden world,some perhaps as close as our ownGalactic neighborhood. To see one'sneighborhood, astronomers mustobserve huge areas of the sky in everydirection. Modern ground-basedtelescopes can do this. All of thetelescopes at Las Campanas, includingthe upcoming Magellan telescopes,are like wide-angle lenses that includereasonably large patches of sky in asingle shot. This makes them perfecttools for the hard but exciting workahead.

• Personnel •Research Staff

Horace Babcock, Director EmeritusAlan DressierWendy FreedmanJerome Kristian1

Patrick McCarthyAugustus Oemler, Jr., Director2

Eric PerssonGeorge PrestonAllan SandageLeonard Searle, Director Emeritus3

Stephen ShectmanIan ThompsonRay Weymann

Staff Associates

Steve Majewski, Hubble Fellow4

Postdoctoral Fellowsand Associates

Julianne Dalcanton, Hubble FellowCarme Gallart, Research Associate5

Mauro Giavalisco, Hubble Fellow6

Bob Hill, Research Associate4

Stephen Landy, Research AssociateLori Lubin, Carnegie Fellow7

Andrew McWilliam, Senior ResearchAssociate8

John Mulchaey, Carnegie FellowRandy Phelps, Research AssociateMichael Rauch, Research Associate4

Brian Rush, Research Associate9

Ian Smail, Research Associate10

Jeffrey Willick, Carnegie Fellow4

Ann Zabludoff, Carnegie Fellow11

Predoctoral Fellows

Rebecca Bernstein, Carnegie GraduateFellowship, California Institute ofTechnology12

Diego Mardones, Carnegie-Chile Fellow,Harvard University11

1MS Campanas Rese,arch Staff

Patricia Knesek, Resident Scientist1'1

Wojciceh Kneminski, Resident Scientist

William Kunkel, Resident ScientistMiguel Roth, Director, Las Campanas

Observatory

Support Scientists

David MurphyAnand Sivaramakrishnann

Supporting Staff, Pasadena

Joseph Asa, Magellan Electronics TechnicianAlan Bagish, Las Campanas Observatory

EngineerRichard Black, Assistant to the Director for

Grants and PersonnelWickie Bowman, Administrative Assistant6

David Carr, Magellan Project InstrumentEngineer

Ken Clardy, Data Systems ManagerMarinus de Jonge, Magellan Project ManagerElizabeth Doubleday, Publications EditorJoan Gantz, LibrarianBronagh Glaser, Administrative AssistantKaren Gross, Assistant to the DirectorSteve Hedberg, Accountant14

Matt Johns, Magellan Project SystemsEngineer

Aurora Mejia, HousekeeperRoberto Mejia, HousekeeperKristin Miller, Magellan Project Administra-

tive AssistantGeorgina Nichols, ControllerGreg Ortiz, Assistant, Buildings and GroundsStephen Pad ilia, PhotographerFrank Perez, Magellan Project Lead EngineerOlga Pevunova, Graduate Research Assistant15

Pilar Ramirez, Machine Shop ForepersonScott Rubel, Assistant, Buildings and GroundsJeanette Stone, Purchasing AgentRobert Storts, Instrument MakerEstuardo Vasquez, Instrument MakerSteven Wilson, Facilities Manager

Supporting Staff} Las Campanas

Victor Aguilera, Magellan Project ElectronicEngineer1'1

Patricia Alcayaga, Administrative Assistant17

Eusebio Araya, Mountain Superintendent1*Hector Balhontin, ChefEmilio Cerdu, Electronics Technician

Yz\v>

Angel Cortes, AccountantJose Cortes, JanitorJorge Cuadra, Assistant MechanicOscar Duhalde, Mechanical TechnicianJulio Egana, PainterJuan Espoz, Mechanic19

Gaston Figueroa, Small Shift SupervisorLuis Gallardo, El Pino GuardJuan Godoy, ChefJaime Gomez, Accounting AssistantDanilo Gonzalez, El Pino GuardJavier Gutierrez, Heavy Equipment OperatorJuan Jeraldo, ChefJuan Luis Lopez, Magellan Project SupervisorLeone 1 Lillo, CarpenterMario Mondaca, Part-time El Pino GuardCesar Muena, Night AssistantSilvia Munoz, Business ManagerHerman Olivares, Night AssistantFernando Peralta, Night AssistantLeonardo Peralta, Driver/PurchaserPatricio Pinto, Electronics TechnicianRoberto Ramos, GardenerDemesio Riquelme, JanitorHugo Rivera, Night Assistant20

Honorio Rojas, Water Pump OperatorOscar Rojas, JanitorHernan Solis, Electronics TechnicianMario Taquias, PlumberGabriel Tolmo, El Pino GuardManuel Traslavina, Heavy Equipment

OperatorDavid Trigo, Warehouse AttendantPatricia Villar, Administrative AssistantAlberto Zuniga, Night Assistant21

Visiting Investigators

Leonardo Bronfman, Universidad de ChileLuis Campusano, Universidad de ChileMichael Fanelli, Goddard Space Flight CenterRobert Fosbury, European Southern Observa-

torySusan Gessner, Goddard Space Flight CenterWolfgang Gieren, Universidad Catolica de

ChileLeopoldo Infante, Universidad Catolica de

ChileJanusz Kaluzny, Warsaw UniversityVijay Kapahi, Giant Meter-Wave Radio

Telescope, Tata Institute of FundamentalResearch, Pune, India

Marc in Kubiak, Warsaw UniversityArlo Landolt, Louisiana State UniversityBarry Madore, California Institute of Technol-

ogyAshish Mahabal, Giant Meter-Wave Radio

Telescope, Tata Institute of FundamentalResearch, Pune, India

Steve Majewski, University of VirginiaIsabel Marquez, Universidad de Chile

' Mario Mateo, University of MichiganJose Maza, Universidad de ChileBeata Mazur, Copernicus Center, Warsaw,

PolandStacy McGaugh, Department of Terrestrial

MagnetismJohn Middleditch, Los Alamos National

LaboratoryBryan Miller, Department of Terrestrial

MagnetismBohdan Paczynski, Princeton UniversityMichael Pahre, California Institute of

TechnologyHernan Quintana, Universidad Catolica de

ChileNeill Reid, California Institute of TechnologyMonica Rubio, Universidad de ChileMaki Sekiguchi, National Optical Observa-

tory, Tokyo, JapanKrzysztof Stanek, Princeton UniversityMichel Szymanski, Warsaw UniversityAndrzej Udalski, Warsaw UniversityAlan Uomoto, Johns Hopkins UniversityWil van Breugel, Lawrence Livermore

National LaboratoryStuart Vogel, University of MarylandJeff Willick, Stanford UniversityDennis Zaritsky, University of California,

Santa Cruz

'Died June 22, 1996-From February 1, 1996'Retired June io, 19964T<> August M, 1995•From March I, 1996'From Januan 1, 19967Fr»»m September 25, 1995'From July 1, 1995'FromOttober i , W'T.«iWniber 14, tW"To Iimr V, 19%

1-From September 1, 1995•To December 31, 1995)4FromJuly 10, 1995! •From March 1, 1995'"From August 18, 1995'•FriKiiJuly \ 1995'To January M, 1996'"'From November 2, 1995-"From November 15, i«•'Retired January M, 1996

• Yt \R

• Bibliography •The Observatories does not have reprintsavailable for the journal articles listed below.However, the abstracts and, in some cases, fulltext of many of the articles are available on theWorld Wide Web at the NASA AstrophysicsData Systems site: <http://adsww.harvard.edu/>or The Astrophysical Journal electronic editionsite: <http://www.journals.uchicago.edu/ApJ/journal/>

Aparicio, A., C. Gallart, Q Chiosi, and G.Bertelli, Model color-magnitude diagrams forHubble Space Telescope observations of LocalGroup dwarf galaxies, Astrophys. ]. Lett. 469,L97, 1996.

Athreya, R., V. Kapahi, P. McCarthy, and W. vanBreugel, Steep spectrum cores of distant radiogalaxies, MNRAS, in press.

Bahcali, J. N. et aL, including R. J. Weymann,The Hubble Space Telescope Quasar AbsorptionLine Key Project. VII. Absorption systems atZ(abs> <1.3, Astrophys. J. Suppl 457, 19, 1996.

Bahcali, N. A., L. M. Lubin, and V. L. Dorman,Where is the dark matter?, Astrophys. ]. Lett.447, L81, 1995.

Barger, A. ]., A. Aragon-Salamanca, R. S. Ellis,W. J. Couch, I. Smail, and R. M. Sharpies,The Life-cycle of star formation in distantclusters, MNRAS 279, 1, 1996.

Bernstein, R. A., W. L. Freedman, and B. F.Madore, Progress report on the Las Campanas/Hubble Space Telescope extragaiacticbackground light program (30O0-8DOOAngstroms), in Unveiling the Cosmic InfraredBackground^ E. Dwek, ed., p. 333, AmericanInstitute of Physics, New York, 1996.

Bower, G., A. S. Wilson, J. Morse, R. Gelderman,M. Whittle, and J. S. Mulchaey, Radio andemission-line jets in the Type 2 Seyfert galaxyMKN 1066, Astrophys. J. 454, 106, 1995.

Brainerd, T. G., R. D. Blandford, and I. Smail,Galaxy halo parameters from weak gravita-tional leasing, in Clusters, Lensingand theFuture of the Universe, ASP Conference SeriesVol. 88, V. Trimble and A. Reisenegger, eds.,p, 225, Astronomical Society of the Pacific,San Franc ihcn, 1996.

Brainerd, T. G.t R. D. Blandford, and I. Smail,Weak tensing by individual galaxies, inAstruphysvccd Applications of GravitationalIxnaingi IAU Symp<»siuni 173, C. S. Kochanekand J, N. Hewitt, cds.» p. 183, Kluwer,Dordrecht, W 6 .

Castro, S., R. M. Rich, A. McWilliam, L. C. Ho,H. Spinrad, A. V. Filippenko, and R. A. Bell,Echelle spectroscopy of a metal-rich K giant inBaade's Window using the Keck high-resolution spectrograph, Astron. ]. Ill, 2439,1996.

Colbert, E. J. M., S. A. Baum, J. E Galiimore, C.P. O'Dea, M. D. Lehnert, Z. I. Tsvetanov, J. S.Mulchaey, and S. Cagnoff, Large-scaleoutflows in edge-on Seyfert galaxies. I. Opticalemission-line imaging and optical spectros-copy, Astrophys. J. Suppl. 105, 75, 1996.

Dalcanton, J., A proposal for finding clusters ofgalaxies at z > 1, Astrophys. J. 466, 92, 1996.

Dalcanton, ]. J., and S. A. Shectman, "Chain"galaxies are edge-on low surface brightnessgalaxies, Astrophys. ]. Lett. 465, L9, 1996.

Dalcanton, J. J., D. N. Spergel, and F. J. Summers,The formation of disk galaxies, Astrophys. J.,in press.

Davis, D. S., J. S. Mulchaey, R. F. Mushotzky, andD. Burstein, Spectral and spatial analysis ofthe intra-group medium in the NGC 2300group, Astrophys. ]. 460, 601, 1996.

de Koff, S., S. Baum, W. Sparks, J. Biretta, D.Golombek, F. Macchetto, R McCarthy, and G.Miley, HST snapshot survey of 3CR radiosource counterparts. I. Intermediate redshiftgalaxies, Astrophys. J. Suppl., in press.

Demers, S., P. Battinelli, M. J. Irwin, and W. E.Kunkel, Evidence for random star distributionsin three dwarf spheroidal galaxies, MNRAS, inpress.

de Vriss, W., C. Odea, S. Baum, J. Biretta, W.Sparks, F. Macchetto, G. Miley, and P,McCarthy, HST snapshot survey of 3CR radiosource counterparts. III. CSS sources,Astrophys. ]. Supply in press.

Dressier, A., Peculiar velocities within R ~ 6000km/s, in Proceedings of the Mount Stromh andSiding Spring Observatories Heron IslandWcwhshop on Peculiar Velocities in the Universe,1996. <http://msowww.anu.edu.au//-heri>n>

Dressier, A., ed., HST and Beyond. Exploration andthe Search far Origins; A Viskmforr Ultraviolet-Optical'lnfrarcd Space Astronomy, Associationof Universities fur Research in Astronomy,Washington, D.C, 1996.

Fahlman, G. G., K. A, Douglas, and I. KThompson, Infrared photometry of theglobular cluster Terzan 6, Astnm. J. 120, 2189,1995.

KsTiinTU'N

Fahlman, G. G., G. Mandushev, H. B. Richer, I.B. Thompson, and A. Sivaramakrishnan, Themain-sequence stars of the Sagittarius dwarfgalaxy, Astrophys. ]. Lett. 459, L65, 1996.

Ferrarese, L, W. L. Freedman, R. J. Hill et al,including R. Phelps, The ExtragalacticDistance Scale Key Project. IV. The discoveryof Cepheids and a new distance to Ml00 usingthe Huhhle Space Telescope, Astrophys.]. 464,568, 1996.

Ferrarese, L. et al, including W. L. Freedman,Discovery of a nova in Virgo galaxy Ml00,Astrophys. J. Lett. 468, L95, 1996.

Freedman, W. L, How old is the universe?:Measuring the expansion rate with the HubbleSpace Telescope, in 1996 IEEE AerospaceApplications Conference, p. 39, IEEE Inc.,Piscataway, New Jersey, 1996.

Freedman, W. L, M31 and companions: a key toBaade's stellar populations then and now, inStellar Populations, IAU Symposium 164, P. C.van der Kruit and G. Gilmore, eds., p. 165,Kluwer, Dordrecht, 1995.

Freedman, W. L, The Hubble Space TelescopeKey Project to determine the Hubble con-stant, in The Cosmological Constant and theEvolution of the Universe, K. Sato, T.Suginohara, and N. Sugiyama, eds., p. 79,Universal Academy Press, Tokyo, 1996.

Freedman, W. LM How old is the universe: new7

measurement with the Hubble Space Tele-scope, in Scieyice Spectra, G. Friedlander, ed., p.20, Gordon and Breach, Newark, 1996.

Freedman, W. L, The HST key project tomeasure the Hubble constant, in Science withthe Hubble Space Telescope - //, P. Benvenuti, F.D. Macchetto, and E. J. Schrein, eds., SpaceTelescope Science Institute, Baltimore, inpress,

Freedman, W. L., and B, F. Madore, The Cepheidextragalactic distance scale, in Clusters,Lensing and the Future of the Universe, ASPConference Series Vol. 88, V. Trimble and A.Reisene^er, eds., p. 9, Astronomical Societyof the Pacific, San Francisco, 1996.

(JiavaHisco, MM A. Koratkar, and D. Calzetti,Obscuration of Ly a photons in star-formingmilaxios, Astrophys. J. 446, 831, 1996.

GiavaliNCo, M., M. Livio, R. C. Bohlin, E D.Niacchetto, and T. P. Stecher, On themurphoh^y of tht' HST faint galaxies Astron.j 112, W , 1996.

CminJj, P. et aL including J. S. Mulchaey. Kl 279iimltiw:ivelen«4th monitoring, II. Ground*k»n\l c.nnpaitfn, Astrttphys. J. 45^> 7$, 1996.

H;unu\, M. et al.» including W. Knemm^ki, B\?RIIs fi! ilints for 29 Type Li >upcrn»*vae, Astron.j , in pros.

Hester, J. J. et aL, including J. Kristian, HuhhleSpace Telescope WFPC2 imaging of Ml6:photoevaporation and emerging young stellarobjects, Astron. J. Ill, 2349, 1996.

Irwin, M. J., S. Demers, and W. E. Kunkel, ThePyxis cluster: a newly identified galacticglobular cluster, Astrophys. }. Lett. 453, L21,1995.

Kaluzny, J., W. Krzeminski, and B. Mazur, CCDphotometry of variable stars in the globularcluster RU 106, Astron. J. 110, 2206, 1995.

Kaluzny, J., W. Krzeminski, and B. Mazur, Openclusters as tracers of the evolution of thegalaxy, in Proceedings of the InternationalSymposium in Granada, Spain, October 1994, inpress.

Kaluzny, J., W. Krzeminski, and B. Mazur,Eclipsing binaries in the old open clusterNGC 2243, in The Origins, Evolution, andDestinies of Binary Stars in Clusters, ASPConference Series Vol. 90, E. F. Milone and ].-C. Mermilliod, eds., p. 152, AstronomicalSociety of the Pacific, San Francisco, 1996.

Kaluzny, J., W. Krzeminski, and B. Mazur, Variablestars in the field of the old open cluster NGC2243, Astron. Astrophys. Suppl. 118, 303,1995.

Kaluzny, J., M. Kubiak, M. Szymanski, A.Udalski, W. Krzeminski, and M. Mateo,Eclipsing binaries and SX Phe stars in OmegaCen and 47 Tuc, in The Origins, Evolution, andDestinies of Binary Stars in Clusters, ASPConference Series Vol. 90, E. F. Milone and J.~C. Mermilliod, eds., p. 38, AstronomicalSociety of the Pacific, San Francisco, 1996.

Kaluzny, j . , M. Kubiak, M. Szymanski, A.Udalski, W. Krzeminski, and M. Mateo, TheOptical Gravitational Lensing Experiment.Variable stars in globular clusters - I. Fields5139A-C in Omega Centauri, Astron.Astrophys. Suppl., in press.

Kaluzny, J., M. Kubiak, M. Szymanski, A.Udalski, W. Krzeminski, M. Mateo, and K.Stanek, The Optical Gravitational LensingExperiment. Variable stars in globular clusters- II. Fields 5H9D-F in Omega Centauri,Astron. Astrophys. Suppl., in press.

Kapahi, V. K., R. M. Athreya, C. R.Subrahmanya, R. W. Hunstead, J. C. Baker, P.J. McCarthy, and W. van Breugel, Cusmologi-cal evolution of linear sizes and the unificationof quasars and radio galaxies, in Asian-PacificAstronomy: Proceedings of the Gr/i Asian-PacificRefund Meeting an Astronomy of the Interna*titmal Astrtmumical L'nion, J. Astrophys. Astran.{Suppl), V. K. Kapahi et aL eds., p. 125,Indhn Academy of Sciences, Bangalore, India,1995.

iv: I 'it ''

Kapahi, V. K., R. M. Athreya, C. R.Subrahmanya, P. J. McCarthy, and W. vanBreugel, Multi-waveband studies of theMolonglo 1-JY sample of radio galaxies, inAsian-Pacific Astronomy: Proceedings of the 6thAsian-Pacific Regional Meeting on Astronomy ofthe International Astronomical Union,].Astrophys. Astron. (Suppl.), V. K. Kapahi et ah,eels., p. 203, Indian Academy of Sciences,Bangalore, India, 1995.

Kassis, M., E. D. Friel, and R. L. Phelps, CCDphotometry of the old open cluster 092-SC18,Astrophys. j . , in press.

Kelson, D., G. Illingworth, W. L. Freedman et al.,The Extragalactic Distance Scale Key Project111. The discovery of Cephids and a newdistance to M101 using the Hubble SpaceTelescope, Astrophys.]. 463, 26, 1996.

Kerber, R, G. Lercher, and M. Roth, IRAS 0652-0337, the Ironclad Nebula, MNRAS, in press.

Knezek, P. M., The morphology of massive, gas-rich low surface brightness galaxies, in NewExtragalactic Perspectives in the New SouthAfrica: The Morphology, Dust, and Gas Contentof Galaxies, Kluwer, Dordrecht, The Nether-lands, in press.

Kormendy, J. et al., including A. Dressier, HubbleSpace Telescope spectroscopic evidence for a 2x 10 solar mass black hole in NGC 3115,Astrophys. ]. Lett. 459, L57, 1996.

Kunkel, W. E., M. J. Irwin, and S. Demers,Carbon stars in the halo of the MagellanicClouds: identification and radial velocity data,Astron. Astrophys. SuppL, in press.

Labhardt, L., A. Sandage, and G. A. Tammann,Method to determine <l> for Cepheids fromscattered observations in I when a completelight curve is known in V, Astron. Astrophys.,in press.

Lahav, O. et al., including A. Dressier, Galaxies,human eyes, and artificial neural networks,Science 267, 859, 1995.

Landy, S. D. The 2D power spectrum of slices inthe Las Campanas Redshift Survey: excesspower and quasi-coherent structure, inMapping* Measuring, and Modelling theUniverse, ASP Conference Series Vol. 94, P.Coles, V. Martinez, and M. Pons-Rorderia,eds., p. 229, Astronomical Society of thePacific, San Francisco, 1996.

Landy, S. D.f S. A. Shectman, H. Lin, R. P.Kirshner, A. A. Oemler, and D. Tucker, Thetwo-dimensional power spectrum of the LasCampanas Redshitt Survey: detection ofexcess power on 100 h s Mpc scales, Astrophys.J. Lett. 456, LI, N%.

Landy, S. I I , A. S. Szalay, and D. C Koo, Strum*angular clustering *>t very blue galaxies:

evidence of a low-redshift population,Astrophys. ]. 460, 94, 1996.

Lauer, T. R., E. A. Ajhar, Y. -I. Byun, A. Dressier,S. M. Faber, C. Grillmair, J. Kormendy, D.Richstone, and S. Tremaine, The centers ofearly-type galaxies with HST. I. An observa-tional survey, Astron. ]. 110, 2622, 1995.

Leibundgut, B. et al, including A. Dressier,Discovery of a supernova (SN 1995K) at aredshift of 0.478, ESO Messenger 81, 19, 1995.

Leibundgut, B. et al., including A. Dressier, Timedilation in the light curve of the distant Typela supernova SN 1995K, Astrophys. ]. Lett.466, L21, 1996.

Lin, H., R. P. Kirshner, S. A. Shectman, S. D.Landy, A. Oemler, D. L. Tucker, and P. L.Schechter, The power spectrum of galaxyclustering in the Las Campanas RedshiftSurvey, in Clustering in the Universe, Proceed-ings of the XXXth Moriond Meeting, C.Balkowski, S. Maurogordato, C. Tao, and J. T.T. Van, eds., Editions Frontieres, Gif-sur-Yvette, in press.

Lin, H., R. P. Kirshner, S. A. Shectman, S. D.Landy, A. A. Oemler, D. L. Tucker, and P. L.Schechter, The luminosity function of galaxiesin the Las Campanas Redshift Survey,Astrophys.]. 464,60, 1996.

Lin, H., R. P. Kirshner, S. A. Shectman, S. D.Landy, A. A. Oemler, D. L. Tucker, and P. L.Schechter, The power spectrum of galaxyclustering in the Las Campanas RedshiftSurvey, Astrophys. ]. 471, 617, 1996.

Lin, H., S. A. Shectman, S. D. Landy, and R,Fong, Large- and superlarge-scale structure inthe Las Campanas Redshift Survey, MNRAS,in press.

Lubin, L. M., The Palomar Distant ClusterSurvey, III. The colors of the cluster galaxies,Astron. J., in press.

Lubin, L. M., R. Cen, N. A. Bahcall, and J. P.Ostriker, The baryon fraction and velocity-temperature relation in galaxy clusters: modelsversus observations, Astrophys. J. 460, 10,1996.

Lubin, L. M., and M. Postman, The PalomarDistant Cluster Survey. II. The cluster profiles,Ascrcm.J. Ill 1795, 19%.

ManJushev, G. L, G. G. Fahlman, H. B. Richer,and I. B. Thompson, A photometric study ofthe globular cluster M55, Astnm. J. 112, 15^6,1996.

Mamn, S. P., with R. ]. Weymann et al, Huhhl>Space Tula^copc observations of the Se>tertgalaxy NGC 3783: discovery of variable C \\absorption, Astruphys, J. 465, 7H W%.

Mateo, M»T P. Fischer, and W. Knenun4a,

41

Variable stars in the Sextans dwarf spheroidalgalaxy, Asmm.J. 110,2166,195.

Mateo, M., N. Mirabal, A. Udalski, M.Szymanski, J. Kaluzny, M. Kubiak, W.Krzeminski, and K. Z. Stanek, Discovery of atidal extension of the Sagittarius dwarfspheroidal galaxy, Astrophys. J. Lett. 458, L13,1996.

McCarthy, P. J., Gas and dust in high z radiogalaxies, in Cold Gas at High Redshift, M. N.Bremer, P. P. van der Werf, and H. J. A.Rottgering, eels., p. 349, Kluwer, Dordrecht,1996.

McCarthy, P. J., S. A. Baum, and H. Spinrad, Theproperties of 3CR radio galaxies. II. Kinemat-ics of the extended emission-lines, Astrophys.). Suppl. 106, 281, 1996.

McCarthy, P. J., V. K. Kapahi, W. van Breugel, S.E. Persson, R. Athrea, and C. R.Suhramhanya, The MRC/1 Jy Radio SourceSurvey. I. Radio galaxy identifications,Astrophys. J. Suppl., in press.

McCarthy, P. J., and C. R. Lawrence, A compositeradio galaxy spectrum from 800 to 5500angstroms, Astron. J., in press.

McCarthy, P., G. Miiey, S. de Koff, S. Baum, W.Sparks, D. Golombek, J. Biretta, and F.Macchetto, HST Snapshot Survey of 3CRradio source counterparts. II. Radio galaxieswith z > 0.5, Astrophys. J. Suppl., in press.

McWilliam, A., G. Preston, C. Sneden, L Searle,and S. Shectman, Chemistry of extremelymetal -poor halo stars, in Formation of theGalactic Halo.. .Inside and Out, ASP Confer-ence Series Vol. 92, H. Morrison and A.Sarajedini, eds., p. 317, Astronomical Societyof the Pacific, San Francisco, 1996.

Moore, B., N. Kan, G. Lake, A. Dressier, and A.Oemler, Galaxy harassment and the evolutionof clusters of galaxies, Nature 379, 613, 1996.

Mulchacy, J. S., D. S. Davis, R. F. Mushotzky, andD. Rurstein, The intra-group medium in poorgroups of galaxies, Astrophys. ]. 456, 80, 1996.

Mulchaey, J. S., R. F. Mushotzky, D. Burstein, andP. S. Davis, High ionization quasar absorptionlines: a test of the existence of hot gas inspiral-rich groups, Astrophys. J. Lett. 456, L5,19%.

Mulchacy, J. S., and A. S. Wilson, An alignmentbetween optical continuum and emission-linestructures m the urcumnuclcar regions ofSevferr galaxies, Astrophys, J. Lett. 455, LI7,

MuLruey, J. S., A. S, Wilson, and Z. T>vetanov,An emis?>it»n-Iine imaging survey of Seytertnuclei in earlv-type host galaxies. I. TheK S i ' r n s , Astruphys. ]. Suppl 102, W,

Mulchaey, J. S,, A. S. Wilson, and Z. Tsvetanov,An emission-line imaging survey of Seyfertnuclei in early type host galaxies. II. Implica-tions for unified schemes, Astrophys. }. 467,197, 1996.

Murphy, D. C, S. E. Persson, M. A. Pahre, A.Sivaramakrishnan, and S. G. Djorgovski, Aninfrared camera for the Palomar Observatory60-inch telescope, PubL Astron. Soc. Pac. 107,1234,1995.

Nairn, A., et al., including A. Dressier, Acomparative study of morphological classifica-tions of APM galaxies, UNRAS 274, 1107,1995.

Paczynski, B., K. Stanek, A. Udalski, M.Szymanski, J. Kaluzny, M Kubiak, M. Mateo,W. Krzeminski, and G. W. Preston, Resultsfrom the Optical Gravitational LensingExperiment (OGLE), in Unsolved Problems ofthe Milky Way, IAU Symposium 169, L. Blitzand P. Teuben, eds., p. 93, Kluwer, Dordrecht,1996.

Persi, P., M. Roth, M. Tapia, A. R. Marenzi, M.Felli, L. Testi, and M. Ferrari-Toniolo,Shocked molecular hydrogen emission in thebipolar outflow NGC 6334- I., Astron.Astrophys. 307, 591, 1996.

Phelps, R. L, and E. A. Lada, Embedded clustersin the Rosette Molecular Cloud, Astrophys. J.Lett., in press.

Postman, M.t L M. Lubin, J. E. Gunn, j. B. Oke,D. P. Schneider, J. G. Hoessel, and J. A.Christensen, The Palomar Distant ClusterSurvey. I. The cluster catalog, Astron, ]. Ill,615, 1996.

Preston, G. W., Axial rotation and incidence ofbinaries among GMP stars, in Formation of theGalactic Hah. ..Inside and Out, ASP Confer-ence Series Vol. 92, H. Morrison and A.Sarajedini, eds., p. 49, Astronomical Societyof the Pacific, San Francisco, 1996.

Rauch, M., R. J. Weymann and S. L. Morris, AreLyman a clouds associated with low surfacebrightness galaxies?, Astrophys. J. 458, 518,1996.

Reid, I. N., L. Yan, S. R. Majewski, I. B. Thomp-son, and I. R. Small, Starcounts redivivus II:deep starcounts with Keck and HST and theluminosity function of the Galactic halo,Astron J, 112, 1472, 1996.

Rich, M., K. J. Mi«hell, W. L. Freedman, and J.I). Neill, Local group populations with theHubble Space Telescope. I. The M31 globularcluster Gl * Mayall II, Astran. J. Ill, 768,1996.

Roth, M-, M. Tupia, R. Vazquez, and A. Femstein,]HK imagmtf photometry of TR 14, TR 15,and TR 16, in The t] Corinae Reiptm: A

\h l\

Laboratory of Stellar Evolution, Serie deConferencias Vol. 2, V. Nliemela, N. Morrell,and A. Feinstein, eds., p. 93, RevistaMexicana de Astronomia y Astroftsica, 1995.

Rutledge, R. E., L. M. Lubin, W. H. G. Lewin, B.Vaughan, B., J. Van Paradijs, and M. Van derKlis, Fast timing and spectral behavior of theRapid Burster, MNRAS 277, 523, 1995.

Saha, A., A. Sandage, L. Labhardt, G. A.Tammann, E D. Macchetto, and N. Panagia,Cepheid calibration of the peak brightness ofSNe la V: SN 1981B in NGC 4536, Astrophys.]. 466, 55, 1996.

Sakai, S., B. F Madore, and W. L. Freedman, Thetip of the Red Giant Branch distances togalaxies. III. The dwarf galaxy Sextans A,Astrophys. J. 461, 713, 1996.

Sakai, S., B. F. Madore, and W. L. Freedman, Thetip of the Red Giant Branch as a distanceindicator for resolved galaxies. IV. NGC 3379:The Leo I Group and implications for thecosmological distance scale, Astron. J., inpress.

Sandage, A., Two lectures on the observationaldetermination of the Hubble expansion rate,in Current Topics in Astrofundarnental Physics:The Early Universe, N. Sanchez and A.Zichichi, eds., p. 403, Kluwer, Dordrecht,1995.

Sandage, A., Bias properties of extragalacticdistance indicators: V. Ho from luminosityfunctions of different spiral types andluminosity classes corrected for bias, Astron. ].Ill, 1, 1996.

Sandage, A., Bias properties of extragalacticindicators: VI. Luminosity functions of M31and M101 look-alikes listed in the RSA2: Ho

therefrom, Astron. J. 11 1, 18, 1996,

Sandage, A., Astronomical problems for the nextthree decades* invited introductory lecture, inKey Problems in Astrophysics, Tenerife Confer-ence, March 1995, Cambridge UniversityPress, Cambridge, in press.

Sandage, A., The controversy about the value ofthe Hubble Constant, in Particles, Strings, andCosmology: Proceedings of the Johns HopkinsWorkshop on Current Problems in ParticleTheory 19 and the PASCOS InterdisciplinarySymposium 5, J. Bagger et ol., eds., p. 317,World Scientific, Singapore, 1996.

Sandage, A., G. Carlson, J. Kristian, A. Saha, andL. Labhardt, The brightest stars in nearbygalaxies. IX. Comparison of ground-based andHST photometry of the brightest stars in IC4182, Astron. J. H i , 1872, 1996.

Sandage, A., A. Saha, G. A. Tammann, L.Lahhardt, N, Panagia, and F. D. Macchetto,Cepheid calibration of the peak brightness of

SNe la. VII. Calibration of SN 1990N inNGC 4639 averaged with six earlier SNe lacalibrations to give HCl directly, Astrophys. J.Lett. 460, LI 5, 1996.

Sandage, A., and G. A. Tammann, An alternatecalculation of the distance to M87 using theWhitmore et al. (1995) luminosity functionfor its globular clusters: Ho therefrom,Astrophys. J. Lett. 464, L51, 1996.

Santiago, B. X., M. A. Strauss, O. Lahav, M.Davis, A. Dressier, and J. P. Huchra, TheOptical Redshift Survey. II. Derivation of theluminosity and diameter functions and of thedensity field, Astrophys. ]. 461, 38, 1996.

Schombert, J. M., R. A. Pildis, J. A. Eder, and A.Oemler, Dwarf spirals, Astron. J. 110, 2067,1995.

Schwarz, H. E., J. -E Claeskens, M. Tapia, and M.Roth, UBVR1 polarimetry of stars in Carinaclusters, in The rj Carinae Region: A Laboratoryof Stellar Evolution, Serie de Conferencias Vol.2, V. Niemela, N. Morrell, and A. Feinstein,eds., p. 69, Revista Mexicana de Astronomia yAstroffsica, 1995.

Schweitzer, A. E, K. M. Cudworth, S. R.Majewski, and N. B. Suntzeff, The absoluteproper motion and a membership survey of theSculptor dwarf spheroidal galaxy, Astron. J.110,2747, 1995.

Shectman, S. A., S. D. Landy, A. Oemler, D. L.Tucker, H. Lin, R. P. Kirshner, and P. L.Schechter, The Las Campanas RedshiftSurvey, Astrophys. J. 470, 172, 1996.

Silbermann, N., et al., including W. L. Freedman,The Extragalactic Distance Scale Key Project.VI. The discovery of Cephcids and a newdistance to NGC 925 using the Hubble SpaceTelescope, Astrophys. J. 470, 1, 1996.

Simpson, C, J. S. Mulchaey, A. S, Wilson, M. J.Ward, and A. AIonso-Herrero, An ionizedcone and dusty disk in Markarian 348: theobscuring torus revealed?, Astrophys. J. Lett.457, LI9, 1996.

Smail, I., and M. Dickinson, Lensing by distantclusters: HST observations of" weak shear inthe field of 3C 324, Astrophys. ]. Lett. 455,L99, 1995.

Smail, U A. Dressier, J. -P. Kneib, R. S. Ellis, W.J. Couch, R. M. Sharpies, and A. Oemler,HST observations of" giant arcs, in Astrtfphysi-cal Applications i>f Gravitational Lensmg, IAUSymposium 173, C. S. Kochanek and J.Hewitt, eds., p. 119, Kluwer, Dordrecht, N%,

Smail, U A. Dressier, J. -P. Kneih, R. S. Ellis, W.J. Couch, R. M. Sharpies, and A. Oemler, Jr.,HST observation* of giant arcs* high resnlu*tion imauing of distant field galaxiesAstrnphysJ, 4tf>, 508,

YEAR

Sneden, C, A. Me William, G. W. Preston, and J.J. Cowan, A detailed analysis of N-captureelements in the ultra'metal-poor halt) giantCS22892-O52, in Formation of the GalacticHalo,..Inside and Out, ASP Conference SeriesVol. 92, H. Morrison and A. Sarajedini, eds.,p. 387, Astronomical Society of the Pacific,San Francisco, 1996.

Sneden, C, A. Me William, G. W. Preston, J. J.Cowan, D. L. Bums, and B. J. Armosky, Theultra-metal'poor, neutron-capture-rich giantstar CS 22892-052, Astrophys. ). 467, 819,1996.

Stanek, K. Z., M. Mateo, A. Udalski, M.Szymanski, J. Kaluzny, M. Kubiak, and W.Krzeminski, Evidence for the galactic bar fromthe two color photometry of the bulge redclump stars, in Unsolved Problems of the MilkyWay, IAU Symposium 169, L. Blitz and P.Teuben, eds., p. 103, Kluwer, Dordrecht, 1996.

Stanek, K., A. Udalski, M. Szymanski, J. Kaluzny,M. Kubiak, M. Mateo, and W. Krzeminski,Modelling the galactic bar using red clumpgiants, Astrophys. J., in press.

Steidel, C. C, M. Giavalisco, M. Dickinson, andK. L. Adelberger, Spectroscopy nf Lyman breakgalaxies in the Hubble deep field, Astron. ].112,352, 1996.

Storchi-Bergmann, T, A. S. Wilson, j. S.Mulchaey, and L. Binette, Excitation andtemperature of extended gas in active galaxies.I. Observations, Astron. Astrophys. 312, 357,

S:vmaiY>ki, M., A. Udalski, M. Kubiak, J.Kaluzny, M. Mateo, and W. Kneminski, TheOptical Gravitational Leasing Experiment.The general catalog of stars in the galacticbulge. I. The stars in the central Baade sWindow OGLE field BWC, Acux Astrun, 46,I, W 6 .

Tammunn, G, A., and A. Sandage, The localvelocity field and the Hubble Constant, inExamining the Bit* Bang and Diffuse BackgroundRadiations, IAU Symposium 168, M. Kutatosand Y. Kurkin edv, p. 163, Kluwer, Dordrecht,

upw, \U M. Ruth, R. A. Vurque:, and A.Femsrein, i'BYRI Imaging Photometry of theTf Carina* region* in Tke TfCanmv Return, ALA/Tutf'Tv uj StdLir Eit'lutinit Sent* deConterencias Vol. 2, \'. Niemela, N. Murrell,-ttiJ A Ft'znsrem, cJ. ., p. 71, RevistaMexi^ana dv A trrn*)inM v Astr* jftsic.i* hW.

ikkcL I\ L , A. OvmkL R. V Kirslmcr, H. Lin,s:. A. Shvcfnun, S. 11 LaiuK, P L Schtxliter,\' Mi;ik% ^. CMttlsiKx mJj. HmasM, The

Las Campanas Redshift Survey galaxy-galaxycorrelation function, MNRAS, in press.

Tucker, D. L, A. Oemler, R. P. Kirshner, H. Lin,S. A. Shectman, S. D. Landy, and P. L.Schechter, Large-scale color segregation in theLas Campanas Redshift Survey, in Clustering inthe Universe, Proceedings of the XXXthMoriond Meeting, C. Balkowski, S.Maurogordato, C. Tao, and j. T. T Van, eds.,Editions Frontieres, Gif-sur-Yvette, in press.

Tucker, D. L, A. Oemler, S. A. Shectman, S. D.Landy, R. Kirshner, H. Lin, and P. L.Schechter, Large-scale structure in the LasCampanas Redshift Survey, in Large ScaleStructure in the Universe, J. P. Mucket, S.Gottlober, and V. Muller, eds., p. 51, WorldScientific, Singapore, 1995.

Turnshek, D. A., M. Kopko, Jr., E. Monier, D.Noll, B. R. Espey, and R. J. Weymann, Far-ultraviolet spectra of broad absorption lineQSOs and constraints on models for theionization structure and metallic ity of theBAL-region gas, Astrophys. ]. 458, 110, 1996.

Udalski, A., A. Olech, M. Szymanski, J. Kaluzny,M. Kubiak, M. Mateo, and W. Krzeminski,The Optical Gravitational Lensing Experi-ment. The catalog of periodic variable stars inthe galactic bulge. III. Periodic variables infour Baade's Window fields: BW5, BW6, BW7and BW8, Acta Astron, 45, 433, 1995.

Udalski, A., A. Olech, M. Szymanski, J. Kaiuzny,M. Kubiak, M. Mateo, W. Krzeminski, and K.Stanek, The Optical Gravitational LensingExperiment. The catalog of periodic variablestars in the galactic bulge. IV. Periodicvariables in three Baade s Window fields:BW9, BW10, BW11, Acta Astron. 46, 51,1996.

Wiilick, J. A., S. Courteau, S. M. Faber, D.Burstein, A. Dekel, and R. Kolatt, Homoge-neous velocity-distance data for peculiarvekxrity analysis. IL Calibration of fieldsamples, Astrophys. J. 457, 460, 1996.

Yi, S., E. Afshari, P. De marque, and A. Oemler,Observational tests for ultraviolet sources inelliptical galaxies, Astrophys. J. Leu. 453, L69,1995.

ZaHudoff, A. I., I). Zaritsky, H. Lin, D. Tucker, Y.Hashimoto, S. A. Shectman, A. Oemler, andR, P. Kirshner, The environment of UE+An

galaxies, Astrophys. J 466, 104, 1996.

ZartNkv, D., S A. Shectm«m, and G. Rredthauer,The Great Circle Camera: A new drift-H/*tnnm*f instrument, Puhl. Astrvn. Sac. Pac.1;N, KM,

• V

-ps •-** **KI rr!.i»/j bu:]dfng, Broad Branch Road campus, autumn !!/%. First row licit toIC:-J div.'ge IVotht/Ji.i, i^blo F.spar/a, Herald Butner, Jtanhua Wang, Richard

, SiiA." i,;r: C;T UT P J U Silver, Pjy; f*>?rastak, Irancois Scrmei/er. N'tison

S;-..iSi^""ij:j A'«n I i-iCc, H*:rrv Bukcr, Dav,d Kutnt/, Cone! Alexander, F.nk Haurj,

V• ".* '.»JA '« : i.v 1 ^::>.p \lu::r' Hii^Jviin. Cknrt; Rur^pker, D a \ d fames, John

*\., " )\ ,*:-.;v. tk***' Bjrjt' -t Cttiiv' WaHc, Sartira KvtstT, Wdio Ron. I j \ t row Akin

"L l\c *if '* S'cu * Sn,.;r, Kfi^i Mur.a F^paT/a Javwr te Pa!r,;tl» Sdivvn Sacks,

a i : ;t; • f /..-nt »> \!)S:1, Ve:.i Ki:^- , ynd Mar> Coder

^ fl R • ,

Director's Introduction

The last twelve months have been an extraordinary year for planetaryscience. In December 1995, the NASA Galileo spacecraft arrived atJupiter and began a series of novel observations of that planet and its

moons, an ordered set of satellites having many parallels to a planetary system. InFebruary, NASA launched what is destined, in several years, to be the first space-

craft to orbit an. THlS

Then I felt like some watcher of the skies . .' r3 * scientists from

When a new planet swims into his ken; NASA JohnsonOr like stout Cortez when with eagle eyes Space Center andHe star'd at the Pacific-and all his men several universi-Look'd at each other with a wild surmise- ties announced

o # 1 i • T^ • t n e discovery, in

Silent, upon a peak in uanen.7 r * a meteorite

}ohn Keats1

thought to comefrom Mars, of

organic compounds and microstructures which they suggest may be the fossilremains of ancient martian lifeforms. And not the least of the notable milestonesof the past year for planetary science were the astronomical detections of planetsaround other stars broadly similar to our Sun. As elated as the poet Keats onreading a particularly fine translation of Homer, planetary scientists have seen newexamples of extrasolar planets "swim into [their] ken" at a breathtaking pace.

In November 1995, Michel Mayor and Didier Queloz of the Geneva Observa-tory in Switzerland published observations of periodic variations in the velocity ofthe star 51 PegasL These variations indicate the presence of a large planet, at leasthalf the mass of Jupiter, with the surprisingly short orbital period of slightly morethan four days* Within three months, Geoffrey Marcy and Paul Butler of SanFrancisco State University had confirmed the discovery and announced a new oneof their own: a planet at least twice the mass of Jupiter in a three-year orbit aboutthe star 47 Ursae Majoris. Since then, further announced discoveries of extrasolarJupiter-mass planets have come at the rate of nearly one per month. The promise'Pi*SIB flit* sonnet "On first It Hiking tntu ChapmanV Hi«ttxer," puHi"»hvd 111 Pi*!tn\i 1817

that full-fledged planetary systems arewithin reach of detection no longerseems improbable. Already there arestrong suggestions of at least two planetsin orbit about the star 55 Cancri, on thebasis of velocity measurements reportedby Marcy and Butler, and the starLalande 21185, on the basis ofastrometric observations by GeorgeGatewood of the Allegheny Observatoryin Pittsburgh.

While the news media, and somescientists, have seized upon the discov-ery of extrasolar planets as fuel forspeculations on the prospects for lifeoutside our solar system, we shouldrecognize that the importance of thesediscoveries for planetary science isenormous. Just as one cannot deducethe laws of probability from only onecoin toss, or unravel the rules of geneticsfrom studies of only one generation, ithas been difficult to claim a full under-standing of how planets form as long asour observations have been restricted toour own planetary system. As thecharacteristics of other planetarysystems are discerned, planetary scien-tists will have both the opportunity andthe responsibility to test and to general-ize their understanding against this newinformation.

At the same time, it is worth remem-bering that the scientific interpretation$ if the properties ot planets around otherstar* will bin Id on several decades ofwhit \\v h;ne learned about stellarevolution anJ aKwt our own solarsWeni. The formation anJ evolution ofplanet* and *ur* has lort^ been a fiicusi >t reHMtth M DTM The firki is markedbx A heahhy balance between fheoHii-

rhe

the processes governing planet forma-tion, theoretical advances now requiresophisticated computer modeling efforts.Two examples of this class of work arewell described in previous Year Bookessays by Alan Boss, on the collapse ofdense interstellar clouds to form youngstars surrounded by orbiting disks of gasand dust (Year Book 92, pp. 111-120),and by George Wetherill, on theformation within the disk of planetesi-mals that grow by gravitational interac-tions to planetary embryos and eventu-ally to planets (Year Book 88, pp. 101—111). Essential complements to numeri-cal modeling are thoughtful programs o{

new observations, which can providestimulus and check to theory. Two suchprograms are described in the essays thatfollow.

In the first, John Graham summarizessome of his recent astronomical observa-tions of young stellar objects, thought tobe promising candidates for sites ofongoing planet formation. Such objects,marked by large quantities of surround-ing gas and light-obscuring dust, are beststudied by imaging at infrared andmillimeter, as well as visible, wave-lengths. There is a richness and com-plexity to the early evolution of starslike our Sun. Graham describes thelarge-scale geometry of the circumstellardisks around two young stellar objects,His observations point to mass electionoccurring at the stellar poles, consistentwith current theory, as well as smaller-scale luminous knots of i»as and timevariations in the distribution of Justindicating clumping on a scale similar tothat thought to be important for planetformation. Strwny variability in theinures nf one of the objects nver a tune-pan ot sTiiy a k-w years points in

energetic and even explosive activity,Graham also describes infrared spectro-scopic identification of ices of water,carbon monoxide, and carbon dioxideon dust grains surrounding young stellarobjects. Because the formation of suchices early in the history of our solarsystem is thought to have been neces-sary to seed the formation of the giantplanets, documenting their distributionaround other young stars at differentstages of development will be animportant task.

The second essay, by ConelAlexander, reviews work at DTM andelsewhere on presolar grains isolatedfrom meteorites. These tiny grains ofdiamond, graphite, and other com-pounds have been identified as predateing the formation of the solar system onthe basis of their highly anomalousrelative abundances of isotopes ofcarbon, oxygen, nitrogen, and otherelements. Their presence in certaintypes of meteorites indicates that thedisk of dust and gas from which theplanets and meteorite parent bodiesformed was never fully vaporized orthoroughly mixed. Most classes ofgrains can he linked to mass-ejectionphenomena in supernovae and redgiant stars. Thus the astrophysicalprocesses that led to the collapse of the

molecular cloud out of which our Sunand planets formed can be studied inthe laboratory by means of chemicaland isotopic analysis of these grains.Because of the tiny dimensions of thegrains, typically micrometers or smaller,the analytical tool best suited for theidentification and characterization ofpresolar grains is the ion microprobe.Alexander's essay describes how thenewly acquired DTM ion probe is beingadapted to this promising avenue ofresearch.

As these essays document, furtherprogress in our understanding ofplanetary systems will require that thenew results from astronomy, cosmo-chemistry, and solar system science beintegrated into the steadily improvingtheoretical models for star and planetformation and evolution. With exper-tise spanning the full sweep of thesedisciplines, DTM staff members areparticularly well positioned to continueto make substantive contributions tothis rapidly growing research area. Asense of the "wild surmise" that Keatsimagined was experienced by the firstEuropeans to glimpse the Pacific canlikely be shared by all who follow thefindings from planetary science over thenext few years.

—Sean C. Solomon

{ \ - T ,•

Time Scales and Stellar Evolutionby John A. Graham

We are easily made aware of the immense range of distances encoun-tered in modern astronomy by just looking up at the sky on a dark,clear night. But we find it hard to comprehend the similar range of

time scales which apply to the stars and galaxies we see out there. For example, astar like the Sun, now 41/2 billion yearsold, requires about 10 billion years to —-—-^-——--^----—-——-———•

traverse its lifetime. Smaller stars evolvemore slowly. Some of them seem to bealmost as old as the universe itself. At theother end of the scale, the core of asupernova like SN1987A in the Large

: Cloud

There is plenty of action ina stellar nursery, where

stars are horn and evolve inever~changing patterns*

terminal mmmm^mmmmmmmmm^mmmmm^m^mmmmmmmmmmm^mm^^^

collapse in less than a second before exploding. The waste nuclear material ejectedby these stars are remnants of a short lifetime—no more than a few million years—of extravagant energy generation.

With the exception of the hydrogen and helium produced in the early universe,most chemical elements can be manufactured only in the hot interiors of stars.Supernova explosions are one way of distributing the elements widely to seedfuture star-forming events. Our own physical and chemical makeup, as well as thatof our surroundings, thus depends on a vast interlocking of different processesoperating on different time scales over a whole galaxy and its history.

As we look back over the 20th century, one of the most impressive achieve-ments in astrophysics has been in our understanding of how stars shine. A star isbound together by gravity. As it contracts (collapsing under its own weight), a partof the gravitational potential energy is converted into heat, which is radiatedaway. In the middle of the 19th century, scientists believed that this was how our

h native Australian, John Graham holds a BJSc* fromthe University of Sydney,, and a Ph.D. (1964) from theAustralian National University* Graham's researchfocuses.on star formation? structure and evolution of

;alaxt,esf and variable stars. He has- been a DTM staffi&entfaer since 1/985•

• Y; <\r \\ K i 95

Sun generated its luminosity. However,it was already becoming clear that theSun didn't have enough potentialenergy to maintain its output of heatand light over geological time. Someother mechanism of solar energy wasneeded.

In the 1920s, Sir Arthur Eddington,one of the early champions of Einstein'stheory of relativity, knew that energyand mass were equivalent. He alsoknew that a helium atom is slightlylighter than four hydrogen atoms. Ifhydrogen could be turned into helium,he suggested, an enormous amount ofenergy could be produced out of themass deficit. It was not clear that starscontain sufficient hydrogen until a fewyears later, when Cecilia Payne-Gaposhkin used the results of stellarspectroscopy to show that the starswere, in fact, made almost entirely ofhydrogen. Later studies by GeorgeGamow, Hans Be the, and othersshowed quantitatively how nuclearreactions in the center of a star, blan-keted to very high temperatures by anextensive outer atmosphere, couldprovide a stable energy source whichwould support the star against collapseand provide radiant heat to its sur-roundings. But what would happenafter the star burned up its availablesupply of hydrogen? In the 1940s,astrophysicists such as Sir Fred Hoyleand Martin Schwarzchild showed thatthe star would go on burning, generat-ing heavier elements starting from hel-ium and proceeding all the way to iron.A key result of this work was that astar's luminosity and lifetime dependlargely on its mass, and that this masschanges very little during a star'sevolution.

Exploring a Stellar Nursery

At DTM we are particularly inter-ested in the state of a star shortly afterits birth. In Year Book 92 (pp. 111-120), Alan Boss discussed his theoreti-cal studies exploring how a new staremerges from the collapse of denseclouds of dust and gas. Observationally,it is difficult to detect newborn stars.Visible light cannot penetrate theobscuring dust within the parent cloud.However, longer wavelength radiationcan get out. Infrared and millimeter-wave instrumentation, developed overthe past two decades, now allows us tosee right into the core of the dustycloud where all the action is. And thereis plenty. Even while the star is stillgrowing by accumulation, strong out-flowing winds are forming. They sweepalmost all excess material from the sur-roundings, eventually to reveal the staras one of the millions we can observeon a starry night. Our solar system wasmade from the little gas and dust leftover from such a clearing process.

Time scales are fairly critical here.Collapse to form a solar-mass starprobably takes a few hundred thousandyears. But clearing of the gas and dustcannot be too quick if planets are toform. It is necessary for the residualmaterial to stay around for a few millionyears in order to form gas-rich planetslike Jupiter and kilometer-size plan-etesimals, which can then grow to formrocky planets like the Earth. Our Sunmay be disconcertingly active now, butat the time oi its formation it must havebeen a thousandfold more so. We knowthat magnetic fields play a verv impor-tant pan in present-dav solar activity,and we Mirnuse that magnetic activ lty

Figure I. A dust cloud in the southern constellation Norma. This image was taken in visual light in May 1995with the 2.5-m du Pont Telescope at Las Campanas Observatory.

was much stronger when the Sun was

young. Infalling material appears to bechanneled into flows, which impact thestellar surface and produce extendedhigh-temperature regions. It is possiblethat the outflowing winds, too, have amagnetic origin. Not surprisingly,irregular light variability is the rulerather than the exception in youngstars as they strive towards some sort ofmature stability.

Many stars form in groups. It can behard, thus, to study the interaction of anewly born star with its surroundingsamid all the other activity in a stellarnursery. There is good reason to payspecial attention to those rarer caseswhere single star formation apparentlyproceeds m isolation. The example 1^ive h m \ though not quite achievingthe ideal state ot isolation, deals withtwo wiJelv separated \ouni* stellariifyects which have recently formed

within a dark dust cloud in the south-ern constellation Norma. Both appearto be of about the same mass as the Sunbut at slightly different points on theirevolutionary paths.

Figure 1 sets the stage. This is animage of a section of the Milky Waytaken in visual light with the LasCampanas 2.5-meter du Pont Tele-scope. The dark dust cloud is not visibledirectly but we know it is there becauseits silhouette is outlined against amultitude of faint background stars. Inits dense parts, the cloud is quiteopaque. We can estimate its distance bycomparing distances of occasionalsuperposed foreground .stars with thoseof a selection of background stars. Thuswe find that the cloud is about 2,000light years from us. In a dark interstellarcloud like this one, there is a continu-ing tug-ot-war going on. Gravitationtries to collapse the cloud while

internal pressure, rotation, and mag-netic fields and tides from neighboringclouds all work to tear the cloud apart.Almost always, gravity loses, and thecloud disperses back into interstellarspace to reform again at a later time,rather in the manner of terrestrialclouds. But on this particular occasion,gravity won, and stars, and perhapsplanets, have been able to form.

The two young stellar objectsobserved in this cloud are identified inFigure 2. Close-up views are shown inFigure 3. The first star, with the cata-loged variable star name V 346 Nor-mae, has cleared away enough materialto be dimly visible through the dust.The second cannot be seen optically.But it does register its presence indi-rectly. Its light is scattered by theenveloping dust and illuminates a faintluminous patch at the outer boundaryof the dust cloud. This patch has beencatalogued as Reipurth 13 and ismarked as Rei 13 in Figure 2. The twostars are separated by about 36,000astronomical units, or half a light year.1

(The astronomical unit is the distancefrom Earth to the Sun).

While obscured in visible light, Rei13 can be detected in infrared light.Figure 4 reproduces an image taken at 2microns with the NICMOS 2 array onthe du Pont Telescope at Las CampanasObservatory in 1991. The centralstellar image of Rei 13 illuminates acurved tail, which is probably part of acomplete cone structure hollowed outot" the Just by the outflowing wind.Most of the remnant material isarranged around the star in the form of

i h i * h> i Tl.!!l'.\t. '2vv ' J u t UUC l.VU1 . ! . ' I lnf k!'i- ' l \ t h v

TtVltlVC v l M . H X i - i l ! . - t l , ' flit1 l l IU 't -l-JiT > *« *lW TV.ll

a thick disk, which rotates on the sameaxis as the star. (There is now strongevidence that such disks surround abouthalf of the observed youngest stars.Some have been imaged directly fromobservations made at millimeterwavelengths by specially designed radiotelescopes.) Rei 13's outflowing windescapes along the path of least resis-tance (i.e., perpendicular to therotating disk). In doing so, it carves outa cone which broadens with time. V346Normae also displays a faint cone-likenebulae. Such conical cavities areknown to be associated with manyyoung stars, one on either side of a star'sdisk. The one on the far side is almostalways hidden from view by the thickdisk.

A young star's clearing wind can bedetected in another way. Small knots ofgas, often no more than several Earthmasses in size, find themselves in the

Figure 2. A more detailed view of the star-forming regionin the Norma cloud. This image is a combination of twomade in hydrogen and sulfur light in April 1991 with the1.0-meter Swope Telescope at Las Campanas. Thelocations of the two embedded stars are marked. Herbig-Haro objects recognized in the area are flagged HH.

< at -v".

^'2^"i^L-^ir-y. * sFigure 3. Details from the image in Fig. I showing the surroundings of thetwo embedded young stars in visual light. Each image is 21 arc seconds onthe side (corresponding to approximately 15.000 astronomical units). The leftimage shows V346 Normae illuminating its surrounding dust. The rightimage is of the nebulous patch Reipurth 13. It is illuminated by scattered lightfrom dust surrounding the embedded star, which is not visible directly atoptical wavelengths.

has been analyzed.The spectrum showsstrong emission linesof hydrogen andionized calcium whichare characteristic ofthe active outeratmosphere of youngstars. Compared toother stars at thisstage of their evolu-tion, the level ofactivity is low. V 346Normae is much more

central, most energetic part of theoutflow, known as the jet. Whenshocked into visibility, these knotsreveal themselves as luminous wispsknown as Herbig-Haro objects. Theirvelocities can be measured and thenused to probe properties of the outflowmaterial (e.g., its extent, orientation,velocity, and age). Neighboring mate-rial from the cloud itself is also swept upand contributes a slower, more massivecomponent to the outflow, which canbe detected with millimeter wavetelescopes. Herbig-Haro objects radiateespecially strongly in the light ofhydrogen and sulfur, and can be mosteasily detected by comparing imagestaken through filter pairs which pass orblock a particular emission line. (Starsradiate at all wavelengths and registerwith both filters.) Herbig-Haro objectsare associated with both of the youngstellar objects described in this essay.They are marked on Figure 2, an imagetaken in hydrogen and sulfur light. (Seealso illustration on p. 56.)

Not much is known about thecentral star in Rei 13; no infraredspectra have been taken. However, thescattered light from the nebula Rei 13

active. No star was known in itsposition until 1983, when it was seenfor the first time at Cerro TololoObservatory in Chile. Examination ofearlier photographs showed that it hadflared up by at least a factor of 100 inthe previous two years. V 346 Normaeis shown in Figure 3 along with itsHerbig-Haro object. The Herbig Haroobject (the fainter of the two objects)was discovered several years before the1983 outburst. This leads us to believethat the present flare-up is only themost recent of many. There are severalother stars with properties similar tothis one. They are grouped together asUFU Orionis" stars. All appear to beaccreting matter from their surround-ings at a very fast rate. For reasons notyet understood, they have a need toradically readjust themselves everythousand years or so by the flaring andthrowing off of a material shell of gaswith a velocity of 300-500 km/sec. The1983 outburst is but the latest of theseepisodes.

The infrared radiation from FUOrionis stars is very strong, indicatingthat local dust is being heated to hightemperatures. Both the ejected shell

54 CARNEGIE INSTITUTION • YEAR BOOK 95

and the intense local heating must beplaying very active roles in dispersingand modifying the material left overfrom star formation. When one looks atthe statistics, it seems possible that allyoung stars go through this mildlyexplosive stage, with long periods ofquiescence in between. Thus, althoughthe star at the center of Rei 13 mayappear dull now, it probably had a moreactive past, and more excitement mayyet be ahead. Change, when it happens,takes place on a time scale of years.

The Nature of Dust Clouds

Locating the dust in FU Orionis starsis difficult. Infrared observationsindicate that dust clouds around thestar are being heated at different times.In addition, the dust appears to hedistributed quite unevenly. V346Normae's appearance, for example, haschanged over the last ten years, indicat-ing a redistribution of obscuring darkmatter. These observations suggest thatthe distribution of dust and gas aroundthese stars is rather clumpy. The gas iseasy to detect because of sharp absorp-tion features seen against the radiatingstar. But dust particles, made up mostlyof carbon or silicates, are large andcomplex structures. They do notimpress such simple absorption featureson light passing through them. Atinfrared wavelengths, however, dust hasmany broad absorption bands, and theygive us intriguing information about itsstate and composition.

The field of infrared spectroseopy isgoing through an exciting phase. Be-cause of heavy, irregular absorptionin mi our atmosphere, and strong, vari-able fhenna! background from the land-

Figure 4. The Reipurth 13 ncbuia imaged at 2.2 micron*. Atinfrared wavelengths, radiation from the embedded starpenetrates the dust (compare Figure 3, right). The starilluminates a cone-shaped scattered-light nebula which ispartly visible in this image taken in April 1991 with theNICMOS 2 infrared array on the du Pont 2.5-m Telescope.This image extends 28 arc seconds on the side. Note theseveral background stars which are detectable in the infraredbecause of the lower opacity of the dust at 2 microns.

based telescope environment, much ofthe important work has been done air-borne. Early data came from the KuiperAirborne Observatory, which operatedfrom a Lockheed C-141 jet aircraft flv-ing above most of the Earth's atmo-sphere. The latest data are comim* fromthe Infrared Space Observatory, whichwas launched in November 1995.

The Infrared Space Observatory hasdetected a multitude of features withindense dust clouds. Water, carbonmonoxide, and carbon dioxide ices allappear to be forming on the dustparticles. Ices are fragile molecules andare quickly destroyed in the har4ienvironment of interstellar sp*icc, Thevcan \inly survive when the Just yraniNon which they form are well protected

Pk VK 95 • t: u;M•

Hubble Space Telescope view of the Herbig-Haro objects HH46 (right) and HH47 (left) in the Gum nebula,another nearby region of star formation. HH47, at the head of a jet of nebulosity, is moving away from theassociated protostar. which is embedded in the bottom right-hand edge of HH46. (Photo by). Morse. STScl, andNASA) Compare this view with the ground-based views of this newly born star and its surroundings published inCarnegie Year Book 87 (pp. 136-137) to realize the abundant new detail revealed by the Hubble Telescope.

within dense, opaque clouds like theone in constellation Norma. V 346Normae is now a bright infrared sourceand emits radiation characteristic ofdust heated to 2000°C. Its spectrumshows a strong water-ice feature. But iceclearly cannot survive temperatures ashigh as 2000°C. Ice grains close to thestar must therefore have been de-stroyed, leaving only cooler materialmore distant from the star. Thus, grainevolution must be going on as aconsequence of the 1983 outburst.

Along with the simplest ices, theInfrared Space Observatory is alsodetecting increasing detail aboutdistinctly organic chemical reactions innewborn stars. The products of suchreactions must be passed to any planetsevolving around the star. Thus, somefirst steps towards the formation andevolution of biogenic molecules, andperhaps pointing to early life, may betaking place at this very early stage ofstellar and planetary evolution. Closerto home, bright comets which swinginto our neighborhood from theoutskirts of the solar system may bepresent-day remnants of the Sun'sprimitive circumstellar ices.

Both young stellar objects discussedin this essay have almost the same age,

Although it is possible they grew fromthe condensation of a single dense dustcloud, deep infrared images of the areashow that the cloud is fragmented intocores, with scales of the order of 7000astronomical units, smaller by a factorof five or more than the distancebetween the two stars. Young as theyare, both stars contain chemical ele-ments which are the products of manyprevious generations of stars. It may bethat the collapse of the two cloud coreswere induced nearly simultaneously byan expanding shockwave from a nearbyolder star nearing the end of its life.Alan Boss and postdoctoral fellowPrudence Foster are now exploring thisscenario at DTM. If a supernova isindeed responsible, then the explosivecollapse of a massive star occurring inless than a second could have triggeredthe formation of two stars which willresemble our own Sun in 41/2 billionyears time. Our Sun will then beentering its own old age and, after aninitial brightening, will move steadilytowards its extinction. Such are thesuperpositions of time scales that weencounter among the ever-changing yetever-regenerating patterns of dust, gas,and stars which we perceive in our viewof the cosmos.

56 CARNEGIE IN-TUITION • YEAR BOOK 95

Stardust in the Laboratoryby Conel Alexander

N ine years ago, researchers isolated from a primitive meteorite the firstgrains of material believed to have formed around stars before the birthof the solar system. Since then, the study of presolar grains, part of a field

informally called laboratory astronomy, has evolved into a truly dynamic,multidisciplinary endeavor, bringing together meteoriticists, chemists, astrono

Cast off of dying starsbefore our own solar

system formed, presolargrains provide

astronomers with somenovel challenges.

mers, and astrophysicists.The search for presolar material in meteor-

ites actually began in earnest in the 1950s. Itwas then that scientists realized that theinterstellar dust from which the solar systemformed—if it survived in primitive, chondriticmeteorites—would have a wide and uniquevariety of isotopic compositions. Fortuitously,the 1950s also saw the advent of high-precision mass spectrometry, which allowedscientists to study the isotopic compositions of meteorites and their inclusions inunprecedented detail. Early hopes of discovering presolar material were dashed,however, when it was found that the isotopic compositions of most elements inlarge samples of chondritic meteorites were identical to those of the Earth. Thisobservation helped formulate the idea that early in its history, the inner solarsystem went through a high-temperature phase that vaporized most or all of theoriginal solid material and hoEiogenized the isotopic compositions of the elements.

The first hint that presolar material survives in meteorites came in 1964, whenresearchers discovered that trace amounts of the noble gas xenon (Xe), having a

Conel Alexander's meteotiticai studies are part of a largereffort to understand! hew the-solar system was .formed. A.native of. England* he 'received, his Pti»D« from the Univer^sity of Essex in 1987* la 1,9I94# alter .several years WOCK* •lag. at Waslilftgioii: Uiiiv€rsif f t -St. Louis,, be accepted astaff |icislt:Ic» at 0TM* ' - • ' " . .

unique isotopic composition, arereleased over a narrow temperatureinterval during progressive heating ofvery primitive meteorites. At first, theXe was thought to be the fissionproduct of a new, superheavy element.This idea soon proved untenable. Thediscovery of several other highlyunusual trace noble gas componentsfollowed, but, despite some attentionfrom astrophysicists, they remainedlittle more than curiosities.

The first actual presolar grains wereisolated by Edward Anders and col-leagues in 1987 at the University ofChicago. The grains turned out to betiny diamonds, only a few nanometers(10'9 m) across. The diamonds containthe Xe component (now called Xe-HL)discovered more than twenty yearsearlier, and Anders and colleaguesdeveloped a technique for isolating

them by using the Xe-HL as a tracer.(The technique necessitates thechemical destruction of more than99.9% of the host meteorite, a proce-dure that Anders likens to burningdown a haystack to find the needle.)The discovery of the nanodiamondswas rapidly followed by the isolation ofseveral other types of presolar grains.(See Fig. 1 and Table.)

The ability to analyze presolar grainsin the laboratory provides an enormousadvantage. The isotopic compositionsof the grains mirror those of the starsfrom which they came, but they can bemeasured with far greater precision andfor a wider range of elements than ispossible astronomically. For instance,the grains of silicon carbide (SiC) havebeen isotopically analyzed for the ele-ments carbon, nitrogen, silicon,magnesium, calcium, titanium, stron-tium, barium, samarium, neodymium,helium, neon, argon, xenon, andkrypton. Of these, typically only carbonand nitrogen are accessible to anastronomer's spectrograph. The isotopicinformation has implications for adiverse range of fields, and it presentsastronomers and astrophysicists withsome novel challenges.

Nanodiamonds: a Major Form ofCarbon in the Qalaxy?

Although they were the first presolar

grains to be isolated, the nanodiamondsremain, in many ways, the mostenigmatic. The isotopic composition of

Figure I, Scanning electron microscope pictures offlop) a presolar SiC grain, and (bottom) a graphitegrain isolated from the Murchison meteorite. Each isapproximately 5 microns in diameter, (Courtesy of Dr.S. Amari, Washington University.)

il\i M, \l b\»]J\ U \ • Yh\H FU K 95

Diamond

SiC

Graphite

AI2O3

MgAI2O4

Si3N4

Biiiiiil

1-5nm

0.1-10jim

1-1OjJ.m

-mm

BRlii"lOOOppm

10ppm

<2ppm

<0.1ppm

~2ppb

~2ppb

.**". -- * lk i

Supernovae and ?

C-rich AGB starsand supernovae

Supernovae andC-rich AGB stars (?)

O-rich AGB stars

O-rich AGB stars

Supernovae

for supernova

Table I. Summary of the types, size range, concentrations, and identified sourcesof presolar grains so far isolated from meteorites. The concentrations are veryvariable. Those listed here are the highest encountered, (ppm and ppb are partsper million and parts per billion, respectively.)

the Xe-HL they contain is best ex-plained by nucleosynthesis during thesupernova explosion of a massive star.But the Xe-HL would have to haveformed deep inside the supernova, anddiamonds could not have grown in thisregion. The best place for the diamondsto have formed is in an outer carbon-rich region, and they could only haveformed after the explosion, as thesupernova expanded and cooled. Thereis evidence that the Xe-HL was im-planted into the diamonds, so the Xe-HL must have been entrained in anenergetic wind that overtook thediamonds. A recent study suggests thatall this happened within hours of thesupernova explosion, a remarkablyshort time given the violence of asupernova, and considerably shorterthan astronomical observations havepreviously suggested for time scales ofdust formation in supernova remnants.

Tii compound the mystery, theaverage carhon isotopic composition ofthe diamonds is very close to solar,which is not what would he expected

diamond carhonisotopes areactually moreconsistent withthose in molecularclouds (thehotbeds of starformation), whosecompositions areclose to solar. Infact, astronomershave recentlyinterpreted amolecular cloudinfrared absorption

feature as possible evidence that 5-20%of all carbon in the dust of molecularclouds may be in the form ofnanodiamonds. Because the fraction ofdust in the Galaxy produced by super-novae is estimated to be only 2-8%,and most of this dust is oxygen- and notcarbon-rich, supernovae are unlikelysources for most of the nanodiamonds.

How can these observations—thatthe Xe-HL is best explained by forma-tion in a supernova while the carbonisotopes and Galactic diamond abun-dances seem inconsistent with asupernova origin—be reconciled? Notall diamonds contain Xe-HL; in fact,most are so small, typically a fewhundred to a few thousand atoms, andthe concentrations of Xe-HL so low,that on average less than one in amillion of the diamonds contains asingle Xe atom. It is possible that thenanodiamonds come from a diverge, but

so far unidentified, rantje oi sourcesand that their uurrvn isotope* are ><

mean of man> types s<t JiK producersin the Galaxy. In thi- u.iv, if nn >*r < •? the

V,

sources produced Xe-free diamonds, theXe-HL signature of the supernova-derived grains would still be detectable.The challenge to astronomers andastrophysicists is not only to explainhow the Xe-HL-bearing nanodiamondsformed but also to identify the othersources of what may be one of the moreabundant forms of dust in the Galaxy.

Qrains from Red Qiant Stars andEvidence of Qalactic ChemicalEvolution

SiC is probably the best-studied typeof presolar grain. Ion microprobeanalyses of individual 1-10 |im SiCgrains, primarily by Ernst Zinner andcolleagues at Washington University,have revealed a remarkable diversity ofisotopic compositions. For instance, thecarbon isotope (12C/13C) ratios of thegrains range from 2 to 7000 (Fig. 2).This compares with a range in naturalterrestrial materials of approximately88-90. Comparing the isotopic compo-sitions of SiC grains with astronomicalobservations and theoretical calcula-tions, one finds that most SiC grainscome from carbon stars, presumably

from many different stars with a rangeof masses and ages.

Carbon stars are some of the maindust producers in the Galaxy. As earlyas the mid-1970s, astronomers observedSiC signatures in the infrared spectra ofcarbon stars. In retrospect, bettercommunication between astronomersand meteoriticists might have led to theisolation of the presolar SiC a decadeearlier, though the meteoritic grains aretypically much bigger than astronomersanticipated.

Carbon stars are low-mass stars(approximately one to four solarmasses), approaching the ends of theirlives. They are in their second giant, orasymptotic giant branch (AGB), phase,and they have enormously extendedbut relatively cool atmospheres. At thebeginning of the AGB phase, freshlysynthesized, carbon-rich material isdredged up from the stellar interior andmixed into the outer envelope of thestar. As soon as this happens, the C/Oratio of the initially oxygen-richenvelope increases rapidly. Once itexceeds one, SiC can begin to form. Itis thought that the SiC grains formnear the stellar surface and are subse-

10000

1000 -

z

• SiC-C-stars• Graphite

SiC-Supernovae

too 1000 10000

Figure 2. The range ofcarbon and nitrogenisotopic compositions inpresoiar SiC and graphitegrains. The SiC grains aredivided into those mostlikely to have come fromcarbon stars and thosedtrlwa from supernovae.The range of compo-sitions exhibited by thepresoiar grains farexceeds thoseencountered or. EarthKoiid lines). Fore\3!Tiple. ;C/!:C ratios interrestrial materials rangehorn about SS to 90.

60 CARNEGIE INSTITUTION • YEAR BOOK 95

quently expelled in the massive windsthese dying stars produce. It may onlytake a few years for a grain to form andthen be expelled from a star, which isvery short compared to the evolution-ary time scale of the star. Consequently,each grain provides a snapshot of theisotopic composition of the star'satmosphere as it evolves.

The carbon-rich material dredged upfrom an AGB star's interior includes awide range of newly synthesizedelements, including Si. Theoreticalexpectations were that the Si isotopesin the SiC would be dominated by thesignature of the dredged-up material,and thus contain a record of the star'sinternal nucleosynthetic processes.However, while the isotopic composi-tion of many elements in the SiC grainsdo conform to theoretical expectations,the Si isotopes do not (see Fig. 3).What the Si isotopes appear to berecording instead is the chemicalevolution of the entire Galaxy. Thecomposition of our Galaxy has evolvedover time, and the elements, built upfrom primordial H and He by succeed-ing generations of stars, have become

Figure 3. The Si Jsotoplc compositions of the

SIC grains thought to have come from carbon

stars. The compositions are expressed as the

deviation, in parts per thousand, from the solar

ratios. These SiC grains are believed to have

formed around stars with masses of one to four

times that of the Sun during their final

asymptotic giant branch phase. During this

phase, carbon-rich material from the star's

interior is mixed into the star's initially oxygen-

rich envelope, ultimately producing a star from

which the SiC an form. The SI Isotopes were

expected to be Influenced by this process and to

plot along a line with a slope of" between 0.2 and

0.5. In fact, the SiC grains form a trend with a

much steeper slope, consistent with estimates of

the change in Si tsotopfc composition during

Gabcttc evolution. Evidently, the SiC grains

come kom numerous stars with different ages.

progressively enriched. Not all isotopesof an element are produced at the samerate, so the isotopic composition of anelement like Si has also evolved withtime. The stars around which the SiCgrains grew formed at different timesand places and therefore inherited avariety of elemental and isotopiccompositions. It is these initial varia-tions in the compositions of the starsdue to Galactic evolution that the Siisotopes are reflecting. Some of the Tiisotopes in the SiC grains also appear torecord Galactic chemical evolutioninstead of stellar nucleosynthesis.Neither Si isotopes nor Ti isotopes canbe measured astronomically and, alongwith astronomical observations ofelemental abundance evolution, theyprovide stringent constraints formodelers of Galactic chemical evolu-tion.

SiC grains are produced at the endof a star's AGB phase, when the star isenriched with carbon. But there issignificant mass lost earlier in the AGBphase, when the envelope and thegrains that condense from it areoxygen-rich. The major condensates

200 -

100 -

50 -

0 -

-50 -

vr.i i * i

-50 SO 100 150 200

YfAR FVA^K 95 • CAKNhC.lt INSTITUTION 61

10000

1000 :

100 -

100 1000 10000 100000

— Cool bottom processing

Galactic evolution

Composition as a functionof mass and initial composition

Figure 4. The oxygen isotopic compositions of presolar oxide grains (solidcircles). Most of the grains fail within the field of the isotopic compositionsobserved in oxygen-rich red giant stars (gray-shaded field), though the size ofthe stellar field may be somewhat exaggerated because of the large errors inthe astronomical data. Much of the variation in these "star-like" grains is dueto variations in initial mass of the parent stars and initial composition of thestar as determined by Galactic chemical evolution. This is illustrated by thethree vertical curves. Each curve shows the predicted oxygen isotopes as afunction of mass (1-3 solar masses) of the stars but for three different initialcompositions. Those grains to the right of the plot with no stellarcounterparts have large, and often extreme. '*O depletions (high i6O/lfiOratios). Theorists have suggested a new process to explain these grains, calledcool-bottom processing (see text). This process appears to occur significantlyonly in stars with solar masses below 2.

under these conditions are siliconoxide-bearing (silicate) minerals.Unfortunately, meteorites are domi-nated by silicates which formed in thesolar system. Since there is no simplephysical or chemical way of concentrat-ing presolar silicates relative to thosefrom the solar system, it is extremelydifficult to find the minor amounts oftiny presolar silicates that must he inmeteorites To date, the onlv presolar

minerals to have

been found are cor-undum (Al2O3) andspinel (MgAl2O4).These oxide grainsexhibit a far largerrange of oxygenisotope compositionsthan has beenobserved astronomi-cally (Fig. 4).

Like the SiC, mostor all of the oxidegrains are thought tohave come from AGBstars. The composi-tion of the oxygenisotopes in AGB starsare largely determinedby two dredge-upevents that occurprior to the beginningof the AGB phase.The final oxygenisotopic compositionof a star depends onthe depth of the twodredge-up episodes,which in turn de-pends on the mass ofthe star. However, therange of oxygenisotopic compositions

exhibited by the grains are too large tobe explained by the dredge ups. As withthe Si in the SiC grains, Galacticchemical evolution appears to havebeen an important influence in produc-ing the oxygen isotopes in these oxidegrains. But even Galactic evolutioncannot explain the isotopic composi-tions of some grains. To explain thej$roup of grains that fall to the far rightin Figure 4, tor example, rhei ntsts haveproposed a new process, called cool-

• Y, IV

bottom processing, in which smallamounts of a star's envelope cyclethrough the hotter, deeper regions ofthe star where nucleosynthesis takesplace and where the oxygen isotope 18Ois depleted.

Qrains from Type II Supernovae

Although most SiC grains originatein carbon stars, about 1% appear tocome from supernovae. These super-nova-derived grains are characterizedby large and highly variable isotopiccompositions. For instance, theircarbon isotope ratios range from 50 to4000 (Fig. 2). The grains also appear tohave once contained several short-livedradionuclides with half-lives as short as45 days. This implies that the grainsformed, at most, a few years after thesupernova explosion. The siliconnitride (Si3N4) grains and a subset ofthe graphite grains also appear to havecome from supernovae. Their Si, N,and C isotopic compositions, forexample, are very similar to those of thesupernova-derived SiC grains. So far,the only grains without a subsetsuspected to have a supernova originare the oxide grains. None exhibit theisotopic characteristics expected ofsupernova material, despite the factthat most supernova material should beoxygen rich.

While the SiC, Si,N4, and graphitegrains have many of the characteristicsexpected of supernova material,explaining all their isotopic composi-tions has proved problematic. Theclassical picture of a typical supernovais i if an onion-shell structure in whicheach shell has a distinct chemical andisotopic character. The best, though by

Carbon-rich zone

Figure 5. A schematic cut-away diagram of asupernova shows fingers of material from deep withinthe star punching up through overlying shells. Thismaterial may mix with carbon in the carbon-rich zoneto eventually form SiC and graphite grains withuniQue isotopic compositions.

no means perfect, fit to the graincompositions appears to require mixingof non-adjacent shells with little

contribution from the interveningmaterial This apparent paradox mayhave been partially solved in recentnumerical simulations showing thatinstabilities develop during a supernovaexplosion, causing fingers of material to

punch up through overlying shells (seeFig. 5). If these fingers can locally mixwith the surrounding shell, it may bepossible to produce the grain composi-tions we see. At present, the grids snthe simulations are too coarse to test

this theory; and the grains remain aconsiderable challenge to theorists.

Developments at Canwgie

The brief description ah»\e high-lights just some of the implication* thatprcsoLir grains have 4or .HTOPJ *UU J F J

astrophysics. Scientists studying thepresolar grains are also using them toelucidate the processes of grain forma-tion around stars and to understandhow the grains are able to survive for upto several hundred million years in theinterstellar medium, where they aresubject to several destructive mecha-nisms. Astronomers are able to use thegrains to augment and constrain theirmodels, and even to place limits on theage of the universe. In studies of oursolar system, the grains are challengingthe theory that all material was vapor-ized and homogenized prior to planetformation. It could be that the presolargrains simply represent a small amountof material that entered the inner solarsystem after the high-temperatureperiod. If not, they may spark a newunderstanding of how the inner solarsystem evolved.

Fairly extensive surveys have beenconducted on the known presolar graintypes, and new subtypes are continuallybeing discovered and identified. Raresubtypes, however, often remain poorlystudied. The oxide grains have provenparticularly difficult to find; even in thepurest residues, 99% of the grains aresolar system in origin. To help locatepresolar oxide grains and some raresubtypes of SiC, groups at WashingtonUniversity and the University of Bernhave developed a successful semi-automated isotope-mapping techniquefor use with their ion microprobes. All

but six of the 88 known presolar oxidegrains have been found in this way.However, the technique can onlydetect the more anomalous grains. Itthus misses about 50% of the presolaroxides in the samples, and it is unableto distinguish many of the SiC subtypesfrom the main SiC population.

At DTM, we are developing a new,highly automated mapping techniqueto search for and analyze (among otherthings) the sought-after presolarsilicates. Our efforts take advantage ofthe enhanced capabilities of DTM'srecently purchased ion microprobe.Larry Nittler, who helped develop themapping technique at WashingtonUniversity, will be joining us in the fallof 1996 as a Carnegie postdoctoralfellow to work on this project. Thetechnique aims to rapidly but preciselyanalyze every grain in a sample. Thiswill enable us to collect an unbiasedsample of presolar oxide compositions,survey large numbers of SiC andgraphite grains to locate significantnumbers of known subtypes, and searchfor new ones. To date, only a smallfraction of the possible types of stellarcondensates have been isolated, andgrains from several important dustproducers have yet to be identified.With these new approaches madepossible by our new ion microprobe, wewill be at the forefront of this young,exciting, and rapidly evolving field.

r,4 \\-;-T\ TJ.'\ • YEAR BOOK 95

• Personnel •

Research Staff

Conel M. O'D. AlexanderL. Thomas Aldrich, EmeritusAlan P. BossLouis Brown, EmeritusRichard W. CarlsonJohn A. GrahamErik H. HauriDavid E. JamesAlan T. LindeVera C. RubinI. Selwyn SacksFrancois SchweizerSteven B. ShireyPaul G. SilverSean C. Solomon, DirectorFouad TeraGeorge W. Wetherill

Senior Research Fellow

Frank Press, Cecil and Ida Green SeniorFellow1

Postdoctoral Fellowsand Associates

Harry J. Becker, NATO PostdoctoralAssociate*1

Ingi Th. Bjarnasorit NSF Associate*Alan D. Brandon, Carnegie FellowHarold M. Burner, NASA AssociateJohn E. Chambers, NASA AssociatePrudence N. Foster, NASA AsMKiateMunir Humayun, Barbara McClintock FellowCatherine L. Johnson, NASA

Assiciate4

John C. Laksiter, NSF Research Fellow inEarth Sciences''

Carolina Lithgow-Bertelloni, NSF ResearchFellow in Earth Sciences

Links Liu, Carnegie Fellow'1

Stac\ S. McGau^h, Carnt^ie Fellow"PatniL J. MeGovem, NASA Awoate*Brwn W. Miller, NASA A ^ u t e 'Elizabeth A MvhiH, Carn tw Fellow ,tnd

Yang Shen, NASA Associaten

Larry P. Solheim, Carnegie Fellow1 H

John C. VanDecar, Harry Oscar Wood Fellow1

and NSF AssociateSuzan van der Lee, NSF Associate15

Cecily J. Wolfe, NASA Associate and HarryOscar Wood Fellow1

Predoctoral Fellowsand Associates

Laurie Benton, University of TulsaRobert A- Dunn, University of OregonGianna Garda, University oi Sao Paulo, BrazilLori K. Herold, Massachusetts Institute of

TechnologyNguyen Hoang, University of Illinois, ChicagoKatherine Hoppe, Princeton UniversityShaosung Huang, Virginia Polytechnic

Institute and State UniversityPatrick J. McGovem, Massachusetts Institute

of TechnologyNoriyuki Namiki, Massachusetts Institute of

TechnologyJasha Polet, California Institute of TechnologyShari Preece, Miami University, OhioMark Simons, Massachusetts Institute of

TechnologyHong Kie Thio, California Institute of

Technology

Research Interns

Katherine Bierlein, National CathedralSchool, D.C.

Lori M- Lanier, University of MarylandFrederick Negre, University of Parih VI,

FranceErik E. R. SchoenfeLJ, Saint Alban\ Schixil,

D.C.Arun Vemurv* Montgi^merv Blair High

Supporting Staff

1 \i\ id I. Rabin*w it;, NASA As*.* x LiteI't't'i^ Runipkvr* C*rm,w fvlhm,

Michael J Aciem* <, C *omiManager

lohn R. Almos t , LihdnMatc .» T. F-ti*:1? »tt% En^jnt'*;

Apprentice1

\*-luntivr•r?r.«

Georg Bartels, Instrument MakerMary McDermott Coder, Editorial AssistantH. Michael Day, Facilities Manager1

Roy R. Dingus, Building Engineer1

Janice Scheherazade Dunlap, Technical TypistJohn A. Emler, Laboratory TechnicianPablo D. Esparza, Maintenance Technician1

Rosa Maria Esparza, Clerk-ReceptionistShaun J. Hardy, Librarian1

Sandra A. Keiser, Scientific ComputerProgrammer

William E. Key, Building Engineer1

Randy A. Kuehnel, Geophysical TechnicianDavid C. Kuentz, Geochemistry Laboratory

TechnicianLucia Lazorova, Library VolunteerD. Carol Lynch, Executive Secretary1

P. Nelson McWhorter, Senior InstrumentMaker

Ben K. Pandit, Electronics EngineerLawrence B. Patrick, Maintenance Techni-

cian1

Daniela D. Power, GeophysicalResearch Assistant

Pedro J. Roa, Maintenance Technician1

Roy E. Scalco, Engineering Apprentice1

Michael Seemann, Design Engineer-Mechanical, Shop Manager

Terry L. Stahl, Fiscal OfficerJianhua Wang, Ion Microprobe Research

Specialist15

David Weinrib, Fiscal AssistantMerri Wolf, Library Technical Assistant1

Visiting Investigators

J. David R. Applegate, Congressional ScienceFellow, American Geophysical Union

Craig R. Bina, Northwestern UniversityIngi Th. Bjarnason, University of Iceland,

ReykjavikInes Lucia Cifuentes, Carnegie Institution of

WashingtonTimothy J. Clarke, New Mexico Institute of

Mining and Technology

Robert L. Dickman, National ScienceFoundation

Sonia Esperanc, a, University of Maryland,College Park

William K. Hart, Miami University, OhioRosemary Hickey-Vargas, Florida Interna-

tional UniversityAnthony J- Irving, University of WashingtonChristopher R. Kincaid, University of Rhode

IslandChristian Koeberl, University of Vienna,

AustriaAllison M. Macfarlane, George Mason

UniversityJulie D, Morris, Washington University, St.

LouisSuzanne W. Nicholson, U.S. Geological

Survey, RestonKazushige Obara, Earthquake Prediction

Research Center, Tsukuba, JapanJeffrey J. Park, Yale UniversityJeroen E. Ritsema, University of California,

Santa CruzStuart Alan Rojstaczer, Duke UniversityRaymond M. Russo, Jr., Universite de

Montpellier II, FranceMartha K. Savage, Victoria University,

Wellington, New ZealandPatrick O. Seitzer, University of Michigan,

Ann ArborYang Shen, Woods Hole Oceanographic

InstitutionDavid W Simpson, Incorporated Research

Institutions for SeismologyJ. Arthur Snoke, Virginia Polytechnic

Institute and State UniversityXiaodong Song, Lamont-Doherty Earth

Observatory of Columbia UniversityNathalie J. Valette-Silver, National Oceano-

graphic and Atmospheric AdministrationElizabeth Widom, National Institute of

Standards and TechnologyDavid R. Williams, National Space Science

Data Center

'Joint appointment with theGeophysical Laboratory

-From July 17, 1995ToLVcemher 31, 19954From October 16, 1995•From November 1, 1995'To September 11, 1995"From September 1, 1995•From June 20, 19%

''Joint appointment with the SpaceTelescope Science Institute,Baltimore

l0FromMay 16, 1996"To March 31, 1996"From May 1, 19961'To July 31, 1995i4To November 30, 1995"From February 1, 1996

66 Or V ,1! lW!T! Ih \ • YEAR BOOK 95

• Bibliography •Reprints of the numbered publications listedbelow can be obtained, except where noted, at nocharge from the Librarian, Department ofTerrestrial Magnetism, 5241 Broad Branch Road,N.W., Washington, D.C. 20015. Whenordering, please give reprint number(s).

5419 Alexander, C. M. O'D., Recycling andvolatile loss in chondrule formation, inChondrules and the Protoplanetary Disk, R. H.Hewins, R. H. Jones, and E. R. D. Scott, eds.,pp. 233-241, Cambridge University Press,Cambridge and New York, 1996.

Barruol, G., R G. Silver, and A. Vauchez,Seismic anisotropy in the eastern US: deepstructures of a complex continental plate, J.Geophys. Res., in press.

5380 Beck, S. L, G. Zandt, S. C. Myers, T. C.Wallace, P. G. Silver, and L. Drake, Crustal-thickness variations in the central Andes,Geology 24, 407-410, 1996.

Bina, C, and P. G. Silver, Bulk sound traveltimes from podal seismology and implicationsfor mantle and core, Geophys. Res. Lett., inpress.

5373 Bjarnason, I. Th., C. J. Wolfe, S. C. Solomon,and G. Gudmundson, Initial results from theICEMELT experiment: body-wave delay timesand shear-wave splitting across Iceland,Geophys. Res. Lett. 23, 459-462,1996.

5390 Boss, A. P., Solar system formation: hot timesin the solar nebula, Nature 377, 578-579, 1995,

5391 Boss, A. P., Giants and dwarfs meet in themiddle, Nature 379, 397-398, 1996.

5401 Boss, A. P., Large scale processes in the solarnebula, in Chondrules and the ProtoplanetaryDisk, R. H. Hewins, R. H. Jones, and E. R. D.Scott, eds., pp. 29-34, Cambridge UniversityPress, Cambridge and New York, 1996.

5402 Boss, A. P., A concise guide to chondruleformation models, in Chondrules and theProtoplanetary Disk, R. H. Hewins, R, H. Jones,and E. R. D. Scott, eds., pp. 257-263, Cam-bridge University Press, Cambridge and NewYork, 1996.

5405 Boss, A. P., Collapse and fragmentation ofmolecular cloud cores. IV. Oblate clouds andsmall cluster formation, Astriphys, ]. 468, 2M-240, 1996.

5411 Boss, A. P., Extrasolar planets, Physics Today49 (n,,. 9), *2-"*8f September 1996."

i414 Boss, A. P, Evolution of the solar nehuli. III.Protoplanetary disks undergoing mass accretion,

Astrophys. J. 469, 906-920, 1996.

Boss, A. P., Binary star evolution: origin andformation, in Report on Astronomy, 1997,Transactions of the International AstronomicalUnion, Vol. 23A, in press.

Boss, A. P., Capture mechanisms, in Encyclo-pedia of Planetary Sciences, J. H. Shirley and R.W. Fairbridge, eds., Chapman & Hail, London,in press.

Boss, A. P., Collapse and fragmentation ofmolecular cloud cores. V. Loss of magnetic fieldsupport, Astrophys. J., in press.

Boss, A. P., Earth-Moon system: origins, inEncyclopedia of Planetary Sciences, J. H. Shirleyand R. W. Fairbridge, eds., Chapman & Hall,London, in press.

. Boss, A. P., The formation of planetarysystems, Astrophys. Space Sci., in press.

5409 Boss, A. P., and H. W. Yorke, Protoplanetarydisks, mid-infrared dips, and disk gaps,Astrophys. J. 469, 366-372, 1996.

5376 Brandon, A. D., R. A. Creaser, and T.Chacko, Constraints on rates of granitic magmatransport from epidote dissolution kinetics,Science 27U 1845-1848, 1996.

5379 Brandon, A. D., R. A. Creaser, S. B. Shirey,and R. W. Carlson, Osmium recycling insubduct ion zones, Science 272, 861-863, 1996.

5382 Brandon, A. D., and D. S. Draper, Con-straints on the origin of the oxidation state ofmantle overlying subduction zones: an examplefrom Simcoe, Washington, USA, Geochim.Cosmochim. Acw6Q, 1739-1749, 1996.

5425 Burner, H. M., Far-infrared spatial observa-tions oi Herbig Ae/Be stars and low mass stars,in The Rok of Dust in the Formation of Stars, H.U. Kaufl and R. Siebenmorgen, eds., pp. 149-156, Springer* Verlag, Berlin and New York,1996. (No reprints available.)

__ Burner, H. M., H. J, Walker, D. H. Wooden,and F. C. Wittehorn, Examples i>f comet-likespectra among p-Pic-like stars, in From Stardustto Ptartetesimah * X. Tielens and Y. Pendleton,eds., Astronomical Sixziery of the Pacific, inpress.

5426 Campbell, M. E. H. M. Burner, P M. Harvev,N. J. Evans II M. B. Camph.41, and C Ns

Sabbev, Radiative transfer rru*dt*l>» of r.ir*IR fromW* IRS 4 and IRS % m The Rok nfDmt m theFitrmaxiim of Stan, H. LI Kaufl ;ind R.Siebenmortfen, eds., pp. W~ H2, Sprmyer-Verfotf, Berlin And New \\&% H%. l'Noreprints available I

Yi W

5369 Carlson, R. W., Isotopic inferences on thechemical structure of the mantle, J.Geodynamics 20, 365-386, 1995.

5377 Carlson, R. W., Where has ail the old crustgone?, Nature 379, 581-582, 1996.

Carlson, R. W., S. Esperanca, and D. P.Svisero, Chemical and Os isotopic study ofCretaceous potassic rocks from southern Brazil,Contrib. Mineral. Petrol, in press.

5392 Carlson, R. W., T. L. Grove, M. J. de Wit, andJ. J. Gurney, Program to study crust and mantleof the Archean craton in southern Africa, Eos,Trans. Am. Geophys. Union 77, 273 & 277,1996.

5375 Chambers, J. E, G. W Wetherill, and A. P.Boss, The stability of multi-planet systems,Icarus 119, 261-268, 1996.

Chambers, J. E., Why Halley-types resonatebut long-period comets don't: a dynamicaldistinction between short and long-periodcomets, Icarus, in press.

5413 de Blok, W. J. G., and S. S. McGaugh, Doeslow surface brightness mean low surfacedensity?, Astrophys.J. (Lett.) 469, L89-L92,1996.

. Eiler, J. M., K. A. Farley, J. W. Valley, E.Hauri, H. Craig, S. R. Hart, and E. M. Stolper,Oxygen isotope variations in ocean island basaltphenocrysts, Geochim. Cosmochim. Acta, inpress.

El Goresy, A., F. Tera, B. Schlick-Nolte, andE. Pernicka, Chemistry and lead isotopiccompositions of glass from a Ramessideworkshop at Lisht and Egyptian lead ores: a testfor a genetic link and for the source of glass, inProceedings of the Seventh International Congressof Egyptologists, Cambridge, September 3-9, inpress.

5386 Ferrarese, L, W. L. Freedman, R. J. Hill, A.Saha, B. E Madore, R. J. Kennicutt, Jr., P. B.Stetson, H. C Ford, J. A. Graham, J. G.Hoessel, M. Han, J. Huchra, S. M. Hughes, G.D. Illingworth, D. Kelson, J. R. Mould, R.Phelps, N. A. Silbermann, S. Sakai, A. Turner,P. Harding, and E Bresolin, The extragalacticdistance scale key project. IV. The discovery ofCepheids and a new distance to Ml00 using theHubbk Space Telescope, Astrophys. J.464, 568-599, 1996. (No reprints available.)

5408 Foster, P. N., and A. P. Boss, Triggering starformation with stellar ejecta, Astrophys. J. 468,784-796, 1996.

French, B. M., C. Koeberl, I. Gilmour, S. B.Shirey, J. A. Dons, and J. Naterstad, TheGardnos impact structure, Norway: petrologyand geochemistry of target rocks and impact ites,Geochim, Cosmochim. Acta, in press.

5393 Garda, G. M., J. H. D. Schorscher, S.

Esperanca, and R. W Carlson, The petrologyand geochemistry of coastal dikes from SaoPaulo State, Brazil: implications for variablelithospheric contributions to alkaline magmasfrom the western margin of the South Atlantic,Anais da Academia Brasileira de Ciencias 67(Supl. 2), 191-216, 1995. (No reprintsavailable.)

Graham, J. A., R. L. Phelps, W. L. Freedman,A. Saha, L. Ferrarese, P. B. Stetson, B. EMadore, N. A. Silbermann, S. Sakai, R. C.Kennicutt, P. Harding, E Bresolin, A. Turner, J.R. Mould, D. M. Rawson, H. C. Ford, J. G.Hoessei, M. Han, J. P. Huchra, L. M. Macri, S.M. Hughes, G. D. Illingworth, and D. D.Kelson, The extragalactic distance scale keyproject. VII. The discovery of Cepheids in theLeo I group galaxy NGC 3351 using the HubbleSpace Telescope, Astrophys. ]., in press.

5383 Hartmann, L, N. Calvet, and A. Boss, Sheetmodels of protostellar collapse, Astrophys. J.464, 387-403, 1996.

5399 Hauri, E. H., Major-element variability in theHawaiian mantle plume, Nature 382, 415-419,1996.

5378 Hauri, E. H., J. C. Lassiter, and D. J. DePaolo,Osmium isotope systematics of drilled lavas fromMauna Loa, Hawaii, J. Geophys. Res. 101,11793-11806, 1996.

5400 Israelian, G., M. Friedjung, J. Graham, G.Muratorio, C. Rossi, and D. de Winter, Theatmospheric variations of the peculiar B[e] starHD 45677 (FS Canis Majoris), Astron.Astrophys. 311, 643-650, 1996.

5398 James, D. E., and M. Assumpgao, Tectonicimplications of S-wave anisotropy beneath SEBrazil, Geophys. J. Int. 126, 1-10, 1996.

5423 Johnson, C. M., S. B. Shirey, and K. M.Barovich, New approaches to crustal evolutionstudies and the origin of granitic rocks: whatcan the Lu-Hf and Re-Os isotope systems tellus?, Trans. Roy. Soc. Edinburgh (Earth Sciences)87, 339-352, 1996.

5385 Kelson, D. D., G. D. Illingworth, W EFreedman, J. A. Graham, R. Hill, B. E Madore,A. Saha, P. B. Stetson, R. C. Kennicutt, Jr., J. R.Mould, S. M. Hughes, L. Ferrarese, R. Phelphs,A, Turner, K. H. Cook,. H. Ford, J. G. Hoessel,and J. Huchra, The extragalactic distance scalekey project. III. The discovery of Cepheids anda new distance to Ml01 using the Hubbk SpaceTekscope, Astrophys.J. 463, 26-59, 1996. .(Noreprints available.)

5395 Kendall, J.-M., and P. G. Silver, Constraintsfrom seismic anisotropy on the nature of thelowermost mantle, Nature 381, 409-412, 1996.

5397 Kenney, J. D. P., R. A. Kcx>pmann, V. CRubin, and J. S. Young, Evidence for a merger inthe peculiar Virgo cluster Sa galaxy NGC 4424,

,u iii I w m IU >\ • YEAR BOOK 95

Astron.J. Ill, 152-159, 1996.

5406 Kincaid, C, and P. Silver, The role of viscousdissipation in the orogenic process, Earth Planet.Sci.Lett. 142,271-288, 1996.

5420 Koeberl, C, W. U. Reimold, and S. B. Shirey,Re-Os isotope and geochemical study of theVredefort Granophyre: clues to the origin of theVredefort structure, South Africa, Geology 24,913-916, 1996.

5374 Koeberl, C, and S. B. Shirey, Re-Os isotopestudy of rocks from the Manson impactstructure, in The Manson Impact Structure, Iowa:Anatomy of an Impact Crater, C. Koeberl and R.R. Anderson, eds., pp. 331-339, Special Paper302, Geological Society of America, Boulder,Colo., 1996.

Koeberl, C-, and S. B. Shirey, Re-Os isotopesystematics as a diagnostic tool for the study ofimpact craters and ejecta, Palaeogeogr.Palaeoclimatol. Palaeoecol. (Proceedings oflGCPProject 293), in press.

5367 Lee, S.-M., and S. Q Solomon, Constraintsfrom Sea Beam bathymetry on the developmentof normal faults on the East Pacific Rise,Geophys. Res. Lett. 22, 3135-3138, 1995.

5418 Lee, S.-M., S. C. Solomon, and M. A. Tivey,Fine*scale crustal magnetization anomalies andsegmentation of the East Pacific Rise, 9°10'-9o50'NJ. Geophys. Res. 101, 22033-22050,1996.

Leffler, L., S. Stein, A. Mao, T. Dixon, M. A.Ellis, L. Ocola, and I. S. Sacks, Constraints onpresent-day shortening rate across the centraleastern Andes from GPS measurements,Geophys. Res. Lett., in press.

5404 Linde, A. T, M. X Gladwin, M. J. S.Johnston, R. L. Gwyther, and R. G. Bilham, Aslow earthquake sequence on the San Andreasfault, Nature 383, 65-68, 1996.

Lithgow-Bertelloni, C, and M. A. Richards,Dynamics of Cenozoic and Mesozoic platemotions, Rev. Geophys., in press.

5384 Liu, L, A. T. Linde, I. S. Sacks, and S. He,Aseismic fault slip and block deformation inNorth China, Pure Appl. Geophys. (PAGEOPH)146, 717-740, 1996.

5417 Liu, L, M. D. Zoback, Y. Lu, and P. Segall,Interseismic strain accumulation in the NewMadrid seismic zone (in Chinese), ActaGeophyskaSinica38, 757-766, 1995. (Noreprints available.)

5394 Lundgren, P. R.t and R. M. Russo, Finiteclement modeling of crustal deformation in theNorth America-Caribbean plate boundary zone,I Geophys. Res. 101, 11317-11327, 1996.

5410 Miller, B. W., The star formation histories ofSculptor Group dwarf galaxies. I. Current starformation rates and oxygen abundances, Astron.

J. 112,991-1008, 1996.

5366 Miller, B. W., and V. C. Rubin, Near nuclearvelocities in NGC 5907: observations and massmodels, Astron. J. 110, 2692-2699, 1995.

Moriarty-Schieven, G. H., and H. M. Burner,A sub-millimeter-wave "flare" from GG Tau?,Astrophys.]. (Lett.), in press.

Natta, A., and H. Butner, Resolving disks inYSOs, in Infrared Space Interferornetry, A.Alberdi et al., eds., Space Science Reviews, inpress.

Nguyen, H., M. Flower, and R. W. Carlson,Major, trace element and isotopic compositionsof Vietnamese basalts: interaction of hydrousEMI-rich aesthenosphere with thinnedEurasian lithosphere, Geochim. Cosmochim.Acta, in press.

Nicholson, S. W., S. B. Shirey, K. ]. Schulz,and J. C. Green, Rift-wide correlation of 1.1 GaMidcontinent rift system basalts: implicationsfor multiple mantle sources during rift develop-ment, Can. ]. Earth Sci., in press.

5428 Nittler, L. R., P. Hoppe, C. M. O'D.Alexander, S. Amari, P. Eberhardt, X. Gao, R.S. Lewis, R. Strebel, R. M. Walker, and E.Zinner, Silicon nitride from supernovae,Astrophys. ]. (Lett.) 453, L25-L28, 1996.

Phillips, R. J., C. L. Johnson, S. J. Mackell, P.Morgan, D. T. Sandwell, and M. T. Zuber,Lithospheric mechanics and dynamics of Venus,in Venus II, University of Arizona Press, Tucson,in press.

5424 Piidis, R. A., and S. S. McGaugh, Could aLocal Group X-ray halo affect the X-ray andmicrowave backgrounds?, Astropkys. J. (Lett,)470, L77-L79, 1996.

5403 Pollitz, E E, and I. S. Sacks, Viscositystructure beneath northeast Iceland* J. Geophys.Res. 101, 17771-17793, 1996.

Pollitz, E E, and I. S. Sacks, The 1995 Kobe,Japan earthquake: a long-delayed aftershock ofthe offshore 1944 Tonankai and 1946 Nankaidoearthquakes, Bull. Seismol Soc. Am., in press.

Richards, M. A., Y. Ricard, C. Lithgow-Bertelloni, G. Spada, and R. Sabadini, Anexplanation of the Earth's long-term rotationalstability, Science, in press.

Rubin, V. G, Bright Galaxies, Dark Matters,American Institute of Physics/AIP Press,Woodbury, New York, in press.

. Rubin, V. C, From an Observer, in CntkdDialogues in Cosmology, Cambridge UniversityPress, in press.

5387 Russo, R. M., and P. G* Silver, Cordilleraformation, mantle dynamics, and the Wilsoncycle, Geology 24, 511-514, 19%.

5389 Russo, R. M., P. G. Silver, M. Franke. W, B.

Ambeh, and D. E. James, Shear-wave splittingin northeast Venezuela, Trinidad, and theeastern Caribbean, Phys. Earth Planet. Inter. 95,251-275, 1996.

5371 Ryan, J. G., W. P. Leeman, J. D. Morris, andC H. Langmuir, The boron systematics ofintraplate lavas: implications for crust andmantle evolution, Geochim. Cosmochim. Acta60, 415-422, 1996.

5388 Rydeiek, P. A., and I. S. Sacks, Earthquakeslip rise time and rupture propagation: numeri-cal results of the quantum earthquake model,Bull Seismol. Soc. Am. 86, 567-574, 1996.

Sandwell, D. T, C. L. Johnson, E Bilotti, andJ. Suppe, Driving forces for limited tectonics onVenus, Icarus, in press.

5370 Schweizer, E, Colliding and merging galaxies.III. The dynamically young merger remnantNGC 3921, Astron.J. Ill, 109-129, 1996.

5422 Schweizer, E, B. W. Miller, B. C. Whitmore,and S. M. Fall, Hubble Space Telescope observa-tions of candidate young globular clusters andstellar associations in the recent merger remnantNGC 3921, Astron.J. 112, 1839-1862, 1996.

Shen, Y., S. C. Solomon, I. Th. Bjarnason,and G. M. Purdy, Hot mantle transition zonebeneath Iceland and the adjacent Mid-AtlanticRidge inferred from P-to-S conversions at the410- and 660-km discontinuities,Geop/rys. Res.Lett., in press.

. Shirey, S. B., Re-Os isotopic compositions ofMidcontinent rift system picrites: implicationsfor plume-lithosphere interaction and enrichedmantle sources, Can. ]. Earth Sci.} in press.

5421 Silhermann, N. A., P. Harding, B. E Madore,R. C. Kennicutt, Jr., A. Saha, P. B. Stetson, W.L. Freedman, J. R. Mould, J. A. Graham, R. J.Hill, A. Turner, E Bresolin, L. Ferrarese, H.Ford, J. G. Hoessel, M. Han, J. Huchra, S. M.Hughes, G. D. Illingworth, R. Phelps, and S.Sakai, The Hubble Space Telescope key projecton the extragalactic distance scale. VI. TheCepheids in NGC 925, Astrophys. ]. 470, 1-37,1996. (No reprints available.)

5381 Silver, EG. , Seismic anisotropy beneath thecontinents: probing the depths of geology,Annu. Rev. Earth Planet. Sci. 24, 385-432,1996.

5396 Silver, P. G., and H. Wakita, A search forearthquake precursors, Science 273, 77-78,1996.

Snoke, j. A., and D. E. James, Lithosphericstructure of the Chaco and Parana Basins ofSouth America from surface-wave inversion, J.Geophys, Res., in press.

Solomon, S. C, Venus: geology and geophys-ics, in Encycbpedia of Planetary Sciences, J. H.Shirley and R. W. Fairbridge, eds., Chapman &

Hall, London, in press.

5412 Takanami, T, I. S. Sacks, J. A. Snoke, Y.Motoya, and M. Ichiyanagi, Seismic quiescencebefore the Hokkaido-Toho-Oki earthquake ofOctober 4, 1994, J. Phys. Earth 44, 193-203,1996.

Tera, E, R. W. Carlson, and N. Z. Boctor,Radiometric ages of basaltic achondrites andtheir relation to the early history of the solarsystem, Geochim. Cosmochim. Acta, in press.

5427 Walker, H. J., H. M. Burner, D. Wooden, andF. Witteborn, Silicate dust around p-Pic-likestars, in The Role of Dust in the Formation ofStars, H. U. Kaufl and R. Siebenmorgen, eds.,pp. 223-226, Springer-Verlag, Berlin and NewYork, 1996. (No reprints available.)

Walker, H. J., V. Tsikoudi, C. A. Clayton, T.Geballe, D. H. Wooden, and H. M. Burner, Thenature of the unusual source IRAS18530+0817, Astron. Astrophys., in press.

5372 Wetherill, G. W, The formation andhabitability of extra-solar planets, Icarus 119,219-238, 1996.

5416 Wetherill, G. W, The formation of habitableplanetary systems, in Circumstellar HabitableZones: Proceedings of the First InternationalConference, L R. Doyle, ed., pp. 193-208,Travis House Publications, Menlo Park, Calif.,1996.

. Wetherill, G. W, Ways that our solar systemhelps us understand the formation of otherplanetary systems and ways that it doesn't, inProceedings of the Conference on Detection andStudy of Extra-Solar Terrestrial Planets, Boulder,Colorado, 15-17 May 1995, H. A. Thronson,ed., in press.

Widom, E, R. W. Carlson, J. B. Gill, and R-U. Schmincke, TlvSr-Nd-Pb isotope and traceelement evidence for the origin of the SaoMiguel enriched mantle source, Chem. Geol.y inpress.

5407 Widom, E., and S. B. Shirey, Os isotopesystematics in the Azores: implications formantle plume sources, Earth Planet. Sci. Lett.142, 451-465, 1996.

5368 Wilcock, W. S. D., S. C. Solomon, G. M.Purdy, and D. R. Toomey, Seismic attenuationstructure of the East Pacific Rise near 9°301Sl, J.Geophys. Res. J00, 24147-24165, 1995.

Wolfe, C. J., I. Th. Bjamason, J. C VanDecar,and S. C. Solomon, Seismic structure of theIceland mantle plume, Nature, in press.

5415 Zandt, G., S. L. Beck, S. R. Ruppert, C. J.Ammon, D. Rock, E. Minaya, T. C. Wallace,and P. G. Silver, Anomalous crust of theBolivian Altiplano, Central Andes: constraintsfrom broadband regional seismic waveforms,Geophys. Res. Leu. 23, 1159-1162, 1996.

70 CARNEGIE INSTITUTION • YEAR BOOK 95

Members of the Department of Embryology, summer 1996: First row (left to right): Earl Potts, Bill Kelly. BillKupiec, Doug Koshland, Brian Harfe. Horacio Frydman, Kim Dej, Maggie de Cuevas. Amy Rubinstein. Secondrow (kneeling): Jia Jia Mai, Melissa Pepling, Kornelia Szabo, Chris Murphy. Eileen Hogan, Pam Meluh, KathleenWilsbach, Allison Pinder. Third row (standing): Pat Cammon, Tammy Wu, Amy Rizzitello, Marnie Halpern,Alejandro Sanchez, Valarie Miller, Mei Hsu, Dianne Stewart. Mary Lilly. Irene Orlov, Sue Dymecki. DianneStern. Fourth row: Allan Spradling. Andy Fire. Chen-Ming Fan. Wye Cheatham. Noah May, Ting Xie, JenniferKalish. Jenny Hsieh, David Furlow, Marija Tadin, Catherine Lee, Paul Megee, Jessica Pamment, Jeff Kingsbury,Tony Mahowald, Michel Bellini, Jennifer Abbott, Vinny Guacci, Joe Gall. Deborah Berry. Haochu Huang, BenRemo, Si-Qun Xu, Steve Farber. Zheng-an Wu. Steve Kostas.

: \i \ F . >h !\>TITI • YEAR BOOK 95

Director's Introduction

Biologists today confront an ironic situation. Individual productivity is at alevel undreamed of only twenty years ago. Solutions to the great questionsunderlying cell function and organismal development, many posed in

previous centuries, are unfolding before our eyes. The theory and practice ofmedicine is being transformed, as we almost weekly witness the detailed explica-tion of yet another cancer or inherited malady. A biotechnology industry, spawnedby the biological revolution, bolsters the economy. Most significantly in the longterm, a deep understanding of biology seems certain to shed new light on pressingmedical, environmental, and social problems, and to create unique new ap-proaches for their amelioration. - — « — _ « - — « « - _ « - • _ « • « • • _ - _ « .

Despite these extraordinary « ^ n interesting measure of aaccomplishments, biologists feel less ^ d e | ) a r t m e n t is t h e

appreciated and less secure than atany time in the recent past. The fraction of its research thatprinciples articulated 50 years ago by leads to improvements in

Vannevar Bush, guiding the growth of experimental methods.... I

research and making the biological believe Our department wouldrevolution possible are now viewed in ^ extremely we\\ i n t h i ssome quarters as indefensibly self- - n

serving. Research funds are slated to &be reduced and focused more heavily -—--———•—--—-———-—--—--—-.

on short-term goals selected by nonscientists. Career prospects for young scientists,now declining toward pre-World War II levels, are expected to sink even further.In response to these changes, competition for shrinking funds and a decliningnumber of positions have reached new heights. Increasingly, biologists and otherscientists feel their experiments must produce results quickly and predictably.

The pressure for rapid, metered productivity cannot fail to impact a crucialaspect of biological research—the development of new techniques. Biology hasalways been driven by experiment, to a far greater extent than in the physicalsciences. The biological revolution was made possible by a series of synergisticadvances in the experimental technology of biochemistry and genetics* However,the development of new techniques is inherently risky and unpredictable. Unless asignificant advance is achieved there may be little to show for substantial expendi-tures of time and effort. Moreover, a new technique is often valued only after it hasbeen successfully applied to a significant problem and come into wide use, ensur-

Yl \K l\

ing further delays in documentedproductivity. These factors contributeto an increasing focus on short-termprojects in established areas, and theydiscourage work on techniques andother areas with long-term payoffs.

An interesting measure of a biologydepartment is the fraction of its re-search that leads to improvements inexperimental methods. I believe thatover the last twenty or thirty years ourdepartment would fare extremely wellin this regard. Nearly every member of

the faculty has developed new tech-niques while working here. Further-more, it is heartening to note thatenthusiasm remains high for theinitiation of such projects. It is particu-larly significant that staff associates, theyoung faculty members most susceptibleto the trends noted above, are active indeveloping new methods. Two suchprojects described this year, by staffassociates Susan Dymecki and PernilleR0rth, hold great potential

Susan Dymecki has perfected amethod for altering the genetic consti-tution of small groups of cells within

developing mice. Most genes functionat diverse times and places duringembryonic development. When a genecannot function due to mutation, theaffected embryo usually becomesabnormal. Because the abnormalitybegins when the gene is first used, theembryo may not survive to reach thestage an experimenter wishes to study.If the embryo does survive, it maybecome so deranged that the directeffects of the mutation become ob-scured. Dymecki's technique, usingwhat is called FLP recombinase, targetsmutations to specific groups of cells atspecific times, greatly extending thepower of genetic analysis. Moreover,her method has a variety of other uses.For example, it can genetically marksmall groups of cells so that theirmovement within the embryo can befollowed during development.

Pernille R0rth has also extendedclassical genetic methods. Two out ofevery three genes in the fruit flyDrosophila (and likely most higherorganisms) can be destroyed by muta-tion without producing effects detect-

S\;f[ rr.errher A-.Jrc"/, Fire (ri^hi) v\;ih rvsl-Ji'Uora! fcildiv Joohong Ahnn.

able in a laboratory setting. Thesegenes probably have subtle influenceson behavior, disease resistance, or otherproperties that cannot be easily studiedoutside of an organism's normal habitat.Experience with bacteria and yeast hasshown that much can still be learnedabout the probable function of suchgenes. When produced in excess or inthe wrong situation, many genes willdisturb cell function in highly informa-tive ways. R0rth's method is extremelyversatile since it allows essentiallyrandom Drosophila genes to be mis-expressed at a time and in a tissueselected by the researcher. Those geneswhose mis-expression has a desiredeffect can be identified and cloned.

"News of the Department

This year the department welcomedstaff member Chen-Ming Fan. Fanstudies the early development of mouseembryos. One of his interests, sharedwith several other staff members, is inlearning how structures that repeatalong the anterior-posterior body axis,such as muscles, nerves, and ribs, arepatterned in the early embryo. Anotherof Fan's interests is to determine therole in brain development played by themouse genes Sim I and Sim2.

Our seminar program was high-lighted this year by the NineteenthAnnual Minisymposium, "ChromosomeOrganization." Carl Wu (NIH), MitziKuroda (Baylor College), WilliamEarnshaw (Johns Hopkins Medical

Chen-Ming Fan

School), Susan Gasser (Swiss Institutefor Experimental Cancer Research),Scott Hawley (University of California,Davis), and Bruce Nicklas (DukeUniversity) presented one-hour talks.

Support of research in the Depart-ment comes from a variety of sourcesbesides the Institution. I and variousmembers of my lab are employees of theHoward Hughes Medical Institute.Others are grateful recipients of indi-vidual grants from the National Insti-tutes of Health, the John Merck Fund,the G. Harold & Leila Y. MathersCharitable Foundation, the AmericanCancer Society, the Jane Coffin ChildsMemorial Fund, the Helen HayWhitney Foundation, the DamonRunyon-Walter Winchell CancerFund, the Pew Scholars Program, theRita Allen Foundation, and the HumanFrontier Science Program. We remainindebted to the Lucille P. MarkeyCharitable Trust for its support.

•—Allan C. SpradMng

Photo, next page; Staff associate Susan pymccki in the W. M. Keck Foundation Laboratory for Vertebrate

Development,

Y$ M ft S • C

Mice Flip Over New Qenetic Techniquesby Susan Dymecki

Since the early 1900s, the house mouse M. musculus has served as an excep-tional model animal for studies of nearly all aspects of mammalian, includ-ing human, genetics. The remarkable utility of this organism is a direct

result of the many sophisticated tools developed to manipulate and study its genes.The first and one of the most important of these tools was generated by Carnegieresearch associates William Ernest Castle and Clarence Little. While a member ofthe Castle group at Cold Spring Harbor in 1909, Little set up the first matings toproduce inbred, genetically homoge- B

neous lines of mice. This was a signifi-cant advance. For the first time scien-tists worldwide were able to experimenton the same genetic material and makemeaningful comparisons. Deriving these

All cells contain virtuallythe same number and kinds

of genes. Susan Dymeckidescribes a way to "erase"genes in specific cells at

specific times during mousedevelopment.

strains was quite an undertaking. Notonly did it require great resolve tomaintain the necessary brother-to-sistermatings, it took intellectual mettle aswell Little's work successfully chal-lenged the view that, because of the presence of recessive lethal mutations in thefounding pairs, inbreeding to homozygosity was impossible. Through his tenacity,Little generated some of the most widely used mouse strains today, including DBA,B6, and BALB/c.

Mouse geneticists continue to develop new technology as driven by experimen-tal need. My own lab is interested in developing new tools to dissect the processesthat transform the homogeneous cells of early embryos into the complex highlypatterned tissues of a newborn. Our work rests on the strong foundation of

Susan Oyniecki teceiivedl both a B.S.E-"afi4 an M»S*E.from the. University of Pennsylvania. la 1984'. Sfie wentmi ta -earn aa M-.-D./Ph-0* •from Johns Hopkins Utiiveivsity 'School ®i Mecflcitte la 1992^-She joined Carnegie'sIJcpartiiieai of Bt&btyotogy 10 1993' as a'staff associate."There she studies ejartbryonEic- pattcttting' in tfefc ttiouse,. •

77

manipulative genetics established inthe mouse over the last two decades.

Increasingly powerful methods havebeen developed to manipulate mousegenes. It is now standard, for example,to transfer genetic material("transgenes") into the mouse from anysource. The vast majority of transgenicmice are generated using a techniquedeveloped at Yale University by JonGordon and Frank Ruddle. In thisprocedure, transgene DNA is injectedinto the nuclei of fertilized eggs, whereit becomes incorporated into the mousegenome and eventually expressed invarious tissues. By analyzing anyabnormalities associated with transgeneexpression, it is then possible to inferaspects of normal gene function.

Another revolutionizing techniquewas the isolation and genetic manipula-tion of embryonic stem ct4ls. Thoughthis technique is the cumulative effortof many labs, the pivotal advance camein 1986 from work by ElizabethRobertson and colleagues while at theUniversity ot Cambridge, and Achimiltn^htet id, of the Max*P!anckInstitute. Robertson andCiosslerindependently developed a method to

culture genetically modified embryonicstem cells so that they would differenti-ate into germ cells when put back intothe mouse embryo. This meant thatgenetic alterations engineered in petridishes could be studied through manygenerations in the mouse. This far-reaching achievement has led to thegeneration of hundreds of mutantmouse strains, many of which areinvaluable to the study of humangenetic disease.

Despite the success of thesetransgenic and mutagenic techniques,the genes and biological processes theyopen for study are limited. Bothmethods yield mice which carry atransgene or engineered mutation inevery cell. If the gene is one requiredfor viability, its loss can be lethal to theearly embryo, precluding furtheranalysis. To increase the number ofgenes and developmental processesaccessible to study, geneticists havebeen working to develop methods tomodify genes only in specific tissues.This new type of genetic manipulationexploits a class of molecules called site-spec if it rea unhinases.

• \-

Erasing a Qene

Site-specific recombinases areenzymes which catalyze recombinationbetween specific DNA sequences. Thetwo best-studied recombinases are Flp,from the yeast Saccharomyces cerevisiae,

and Cre, from the bacteriophage PLEach recombinase recognizes andrecombines a distinct sequence of DNAcalled a recombination target site.When these target sites are orientedhead-to-tail on the same DNA mol-ecule, the recombinase excises theDNA lying between them, joining thesequences on either side with base-pairprecision. This is illustrated schemati-cally in Figure 1. Although bothrecombinases are derived from muchsimpler organisms, they seem tofunction quite well in a wide variety ofenvironments, including mammaliancells. As a result, many researchers—tantalized by the prospect of beingable to control precisely when andwhere genes are deleted—have

Figure I. Schematic of Fip~mediated recombinationreaction. Flp recombinase target sites are depicted asblack triangles oriented head-to-tail on a DNAmolecule. In this configuration, Flp recombinaseexcises the DNA lying between the two target sitesand joins the sequences on either side. This reactioncan be used to delete hypothetical gene "A" lyingbetween the target sites, or to activate a markertransgene "BM by excising previously Inserted DNA,

begun testing these enzymes in mice.In theory, it is possible to flank a

gene with recombinase targets, addrecombinase, and delete the gene (Fig.1). In this way, a gene can be erasedonly in those cells to whichrecombinase has been added, and theeffect can be analyzed without compro-mising the organism. This has beencalled "conditional mutagenesis."Alternatively, a recombinase can beused to activate a marker transgene ('B'in Fig. 1) by excising previouslyinserted DNA. Elegant studies in thefruit fly have shown how the latterstrategy can be used to mark and studyspecific populations of cells during flydevelopment. Flp recombinase is nowbeing used successfully by many Droso*

phila geneticists, and results using Crein mice look very promising. My ownlaboratory has been working to estab-lish Flp as a tool for studying embryonicpatterning in mice.

Stephen O'Gorman and GeoffreyWahl of the Salk Institute were the firstto show that Flp can efficiently catalyzesite-specific recombination in mamma-lian cell culture. Building on this work,my lab has demonstrated that Flp isboth necessary and sufficient to recom-bine and delete genes in the mouse. Ibegan these studies by first assessingwhether Flp expression alone wouldhave any adverse affects; if high levelsof illegitimate recombination were tooccur as a result of Flp expression, theresulting embryo would be highlyabnormal and the technique would beuseless. This was not my experience,however. The mice I generated ex-pressed Flp in nearly all tissues yetnever showed any associated abnor-malities. Encouraged by these results, I

Yi \K NLUH: INSTITUTION

Figure 2. The transgenic mouse embryos shown herehave been engineered to express Flp using controlelements from a gene (Wnt-I) normally expressed inthe dorsal aspect of the developing central nervoussystem. Dark staining reflects Flp mRNA.

went on to test whether Flp could beused to delete genes in vivo. I tested twodifferent types of DNA substrates, anintroduced transgene and an endog-enous gene, each flanked by Flprecombination target sites. Aftercrossing to the Flp-producing mice andanalyzing the offspring, I observed thatboth the transgene and the endogenousgene were deleted in a wide variety oftissues.

So far so good. But would briefexpression of Flp in the mouse embryobe sufficient to delete genes duringdevelopment? By using regulatory DNAsequences from a gene called Wnt*l,

which is normally expressed only in thedorsal aspect of the embryonic centralnervous system (see Fig. 2), I limitedwhere and how long Flp would bepresent in the embryo. Subsequentmolecular analyses showed that dele-tion of the target gene occurred in theembryo, and was restricted, as I desired,to neural tube-containing tissue. Theseresults provided the first demonstration

that regulated gene deletion could beachieved in the embryo, and hasestablished Flp as a tool for geneticmanipulations in mice.

'New Aspects of Development

I have since used Flp to follow thefate of neural cells during development.By tracking the adult fate of cellsmarked by gene deletion in the embryo,I have uncovered an interesting aspectof mammalian brain development: cellswhich transiently expressed WntA inthe embryonic neural tube do surviveand eventually populate the adulttectum, cerebellum, brainstem, andspinal cord. Given the great diversity ofneuronal cell types in each of theseadult brain tissues, it is now critical thatI determine exactly which neurons ineach tissue are marked, and thereforecome from Wnt-l-expressing cells inthe embryo. This type of analysis willdefine some of the principles thatcontrol diversification and patterningof the nervous system, and will likelyreveal new insights into the geneticmechanisms underlying various humanbrain defects.

In addition to using site-specificrecombination to study nervous systemdevelopment, I have also initiatedgenetic experiments to uncover moregeneral determinants of tissue pattern-ing. One such interesting class ofregulatory factors is the transforminggrowth factor (3 family (TGFp) ofsecreted molecules. These smallsignaling molecules have been shownto play a role in the development ofnearly all mammalian organs, includingthe nervous system. Although manyTGFp-like molecules have been

o • Yi

mutant

Figure 3. New mouse mutant with skeletal defect. Alizarin red skeletal preparations from a representativehomozygous mutant mouse is shown with an age-matched wild-type mouse. Most prominent is the loss ofphalangeal bones in the digits.

identified, a remaining challenge is toidentify other components in theirsignaling pathways. I have recentlyobtained a potential handle on one ofthese molecules.

I identified a transgene insertionalmutation that exhibits skeletal defectsanalogous to a known TGF(3-familymutation. In these mutant mice, thelength and numbers of bones in thelimbs are reduced. Most noticeable isthe loss of bones comprising the digits;the proximal and medial phalanges areeither absent or are significantlyreduced in size and fused as a singlebone (Fig. 3). Because our geneticanalyses indicate a novel mutation, Iam currently in the process of identify-

ing the affected gene. Whether themutation be in a new TGF(3 familymember, its receptor, a downstreamtransducer, or in an alternative path-way, it will be exciting to unravel howthis molecule organizes embryonictissues.

The cumulative work of mousegeneticists over the last century hasprovided many tools to study geneticaspects of mammalian development andhuman disease. The ability to manipu-late genes with increasing precision andspecificity should enable us to learn stillmore about the dance between ourgenes, our environment, and ourselves."Mousers" will surely be kept busy wellinto the next century.

Yl V 81

Modern Qeneticst A ModularMis-expression Screen in Drosophila

by Pernille R0rth

Genetic screens are powerful tools for biological research. They enableresearchers to identify genes which control a particular biologicalprocess, and, at the same time, learn a lot about that process. Experimen-

tal organisms like Drosophila melanogaster, whose genetics have been well charac-terized over the past century, make efficient screens possible.

The first step of a genetic screen is to make a large number of random mutations(alterations) in the genome. A single mutation, inactivating a single gene, canmanifest itself by a specific change in « _ - « « _ _ « « « « « « _ ^ _ « - - _ _

appearance or behavior. In a traditionalDrosophila screen, genes are disrupted atrandom by the chemical mutagenesis ofthe sperm of adult males. The second stepof a genetic screen is to examine themutagenized flies' progeny (or later -—————-—«--—••••—--————-«

generations) for specific defects. If one

wishes to study eye development, for example, one would look for flies withabnormal eye morphology or impaired vision. Once an interesting mutant strain isidentified, the gene affected by the mutation can be cloned and analyzed.

Genetic screens can allow geneticists to deduce some of the fundamentalprinciples underlying a process even before the genes involved are molecularlyidentified. A good example of this are the screens performed by ChristianeNusslein-Volhard and Eric Wieschaus, who wanted to understand how the basicbody plan of Drosophila embryos was determined. In their screens, they looked atthe cuticle, the outside surface of the fully developed embryo. They realized that

Pernille R0rth describes anovel way to identify and

analyze the function ofgenes in the fruit fly.

PetitiHe R0rth, a native of Denmark, has been a staffassociate In the Department of Embryology since 1994*Before joining Carnegie-, she earned a Cand. Scient. in,.biology in 1990 followed: by a Pli.0. in molecularbiology in .1993* both, from the University ofCopenhagen. •

I v r m Tu • Yt Mi K 95

The fruit fly Drosophila melanogaster, used for nearly a century by geneticists and developmental biologists.

the precise pattern of the cuticle (thenumber of subdivisions and appearanceof body hairs) was a good indicator forthe underlying early patterning events.They also realized that the way muta-tions changed this pattern reflectedhow the early patterning was con-trolled- For this work, they (withEdward Lewis) were awarded a 1995Nobel Prize.

A sophisticated type of geneticscreen, called a genetic interactionscreen, can be used to identify geneproducts that work together in abiological pathway. The starting pointfor an interaction screen is a mildmutation affecting a known componentin the pathway of interest. Mutantanimals are then screened for secondarymutations that either correct for theoriginal mild defect or make it signifi-cantly worse. If the secondary mutationhas such a specific effect, its disruptedgene is probably also involved in thepathway. Genetic interaction screenshave been used successfully to studycellular signaling pathways in Drosophila* Because molecular pathways inflies and mammals are similar, results

with Drosophila can be directly relatedto the signaling that controls growthand differentiation in mammals. This isconvenient, because it is very costlyand time-consuming to do geneticscreens in mammals.

Although traditional genetic screensare wonderful tools for biology, they dohave limitations. For one, even whenan interesting mutant is identified, thechemical mutagen used to make themutation often makes it hard toidentify which gene is actually dis-rupted. Also, many genes do not causedetectable defects when disrupted;sometimes other genes mask the defectby assuming the mutated gene's func-tion. And finally, interaction screensonly work well if the starting mildmutation is reliable,, easy to analyze,and exquisitely sensitive. Such muta-tions are hard to find.

Fortunately, there are other ways tolearn about genes and gene function ina living organism. Instead of studyingwhat happens when a gene is absent,we can study what happens when it isexpressed at a higher than normal level(over*expres*»ion) or in the wrong cell

Yi M- ft • 1 Iw-r T,

(mis-expression). Many informativebiological changes are caused by mis-expression of genes. For example,striking transformations of Drosophila

body segments, such as the appearanceof legs instead of antenna, are caused bymis-expression of so-called homeoticgenes. Homeotic genes are now knownto be important for regional patterningin many animals. Also, the originalidentification of myogenic (muscle-forming) factors in mice was based onthe observation that mis-expressedfactors can convert other, nonmusclecells into muscle. Finally, the initialmolecular understanding of cell growthand cancer was greatly aided by findingthat certain genes cause benign ormalignant tumors when over- or mis-expressed.

I decided it would be useful to have agenetic screen based on mis-expressionin Drosophila. I wanted the screen toidentify genes which, when over- ormis-expressed in a tissue and at a timeof choice, give a specific phenotype ormodify an existing mutant phenotype(i.e., a genetic interaction). In yeast,over-expression screens have helpeduncover the functions and interactionsof many genes. But no one had triedthis type of screen in a multicellulareukaryote, so I set out to develop themethodology.

Before I continue, I should point outthat some geneticists maintain that theonly acceptable way of doing a geneticscreen is the traditional way, despite theexamples given above. The key thing toremember is that over- or mis-expres-sion experiments provide informationabout what a gene can do. This is notnecessarily the same thing as what agene does do under normal circum-

stances. It is important to address thespecificity of a mis-expression pheno-type (i.e., is it a defined change or iseverything messed up?). It is also usefulto compare the mis-expression pheno-type with the phenotype that emergeswhen the gene is disrupted. (One wouldexpect over-expression and disruptionof a gene to have opposite geneticinteractions.) The system I havedeveloped, called the modular mis-expression screen, provides efficientways to deal with both these issues.Furthermore, the results I have ob-tained with my mis-expression screenfit very well with expectations fromtraditional screens. Thus it seems clearthat this novel method can, indeed,uncover biologically relevant effects.

Testing the Screen

In designing the modular mis-expression screen, I took advantage oftwo very useful techniques in Droso-

phila: single P-element mutagenesis,developed by Allan Spradling, GeraldRubin, and others; and the GaHsystem, developed by Andrea Brandand Norbert Perrimon (HarvardMedical School). P elements are small,movable bits of DNA which wheninjected into Drosophila embryos caninsert into the genome. A P elementcan mutate a gene simply by insertinginto or next to it. Because the sequenceof the P element is already known, ittags the insertion spot, and the mutatedgene (or any nearby gene) can easily berecovered. GaH is a transcriptionalactivator protein. It can bind to aknown DNA sequence (a GaH bindingsite) and activate a nearby promoter,turning on the gene regulated by that

• YFAK

Pattern line Target lines

Pattern P-element

etc.

etc.

Figure 1. Outline of the modular mis-expression screen. Flies from the pattern line (top left) carry a patternelement and therefore have Gal4 expressed in a specific tissue, for example in the developing eye. The targetflies (top right) each contain a single target element at an unknown position in the genome, often right next toan endogenous gene. (Fortunately, P elements have a tendency to insert adjacent to genes.) When pattern andtarget flies are mated, their progeny will contain both elements. Gal4 binds to its binding sites within the targetelement, stimulates the promoter (arrow), and thus induces expression of whatever gene is adjacent to thetarget element. If the phenotypic effect of this expression is interesting, the endogenous gene responsible for Itcan easily be cloned and analyzed.

promoter. Gal4 protein and Gal4binding sites are not normally presentin Drosophila but will function ifartificially introduced.

The mis-expression screen has twoparts, or modules: "pattern" flies and"target" flies (Figure 1). Each of thepattern flies contains a P elementbearing the gene that codes for GaHprotein and regulatory sequences thatcontrol which tissue Gal4 is produced

in. Adult flies carrying this GaHpattern element are crossed to a largepopulation of target flies. Each target flycarries a single target P element at somerandom place in its genome. The targetP element contains binding sites for theGaH protein and a promoter at one ofits ends*

The target and pattern elements areinactive on their own. When patternand target flies are mated, however,

Yi \u

GAL4 alone

GAL4 expression pattern in eye disc

Figure 2. Looking for genes that affect eye development. Theleft panel shows an eye disk (the structure that will become theeye) of a larva from a particular pattern line expressing Gal4.The cells that express Gal4 are darkly stained. Over time, mostcells in the eye disc will express Gal4. As shown on the topright panel, Ga!4 expression alone does no harm: the eye looksnormal. Flies that also contain a particular target insert (#100)have abnormal, rough eyes (bottom right panel). Thus, mis-expression of the endogenous gene adjacent to target insert#100 affects eye development.

Rough Eye

their progeny will contain both ele-

ments. This results in over- or mis-

expression of an endogenous Drosophila

gene in the following manner: In cells

producing Gal4 protein, Gal4 will bind

to its binding sites on the target P

element and activate the target's

promoter (see Fig. 1), The promoter

then turns on whatever gene happens

to be adjacent to the target element. If

interesting phenotypes result from this

over- or mis-expression, the endog-

enous gene can be recovered and

analyzed.

The insertion site of the target

clement determines which endogenous

«ene will he activated. The target P

element is thus the "mutagen" in this

tvpe 4jf screen. The fact that the target

element is a randomly transposing P

element makes it possible to generate

many different target flies each having

a different insertion site. It also facili-

tates the cloning of the mutated

(adjacent) gene. The modular design

makes the screen flexible: genes can be

induced in any spatial or temporal

pattern by simply using pattern lines

with different G a H expression patterns.

Finally, by keeping the pattern and

target elements apart and inactive until

mating them in the test cross, one can

recover target inserts that are lethal or

sterile when activated.

To test the method, I performed a

simple screen, focusing on the eye.

Perturbation of eye development in

Drosophila leads to a rough-eye pheno-

type, which is clearly visible in a

dissecting microscope (Fig. 2)* Because

a number of genes important for eyedevelopment have already beenidentified, I knew what to expect (orrather hope for). After I optimizedcomponents of the method, the screenwas successful. I crossed a pattern lineexpressing GaH in the developing eyeto 163 target lines. Six (4%) of thetarget lines gave distinct dominantphenotypes (i.e., rough eyes) in theprogeny when, and only when, theGal4 pattern element was present. (Seeexample in Fig. 2.) Molecular analysesconfirmed that genes adjacent to targetelements were being over- or mis-expressed by Gal4 activation.

Taking advantage of the system'smodularity, I looked for effects in othertissues by crossing my six target lines toother Gal4 pattern lines. Three of thetarget elements only affected eyedevelopment, three had effects in othertissues as well. When I cloned theDNA adjacent to those target elementsaffecting only eye development, I got avery pleasant surprise. One element had

inserted right next to the gene encod-ing GTPase-activating protein (GAP).This was a nice result because it agreedwith previous traditional geneticexperiments showing that GAPexpression was critical for correct eyedevelopment. GAP converts the activeform of a protein called Ras to aninactive form (see Fig. 3A).

To confirm that increased GAP wascausing the rough-eye phenotype bydecreasing Ras activity, I tested theeffect of reducing Ras activity evenfurther by introducing a mutation inRas itself. As expected, this made therough-eye phenotype much more severe(compare Fig. 3D to Figs. 3B and 3C).Finding the insertion in GAP andshowing how it interacts with Rasproved that the method can identifybiologically relevant effects and geneticinteractions, as it was designed to do.

Future Directions

Having shown that the mis-expres-

Figure 3. Consequences of altering Ras activity in the eye, A certain amount of active Ras Is reopired for correcteye development. Too much or too little distorts the process. Panel A: GAP protein converts active Ras to theinactive form. (Another protein converts inactive Ras to the active form, tot Is omitted for clarity. J Panel 8:This eye has lower than normal levels of Ras protein, bui there is still enough active 'Ras to give a normal-looking eye. Panel C: GAP is over-expressed in this eye. As a result, too much Ras protein is inactivated andthe eye is abnormal (i.e.. rough). Panel D: GAP is being over-expressed, but new there ts too little Ras proteinto begin with (as the eye In B). The result Is an even further reduction in the level oi active Ras, causing the eyeto be severely deformed. This is an example of a genetic Interaction, showing that Ras and GAP at! together.

sion screen works, we are now set tocarry out a large-scale screen. Withsupport from the Berkeley Drosophila

Genome Project, we are generatingabout 2,000 target lines, each poten-tially mutating a different endogenousgene. The target inserts are made byallowing a target element to transpose(jump around) in the genome in acontrolled fashion. Because the targetlines have no inherent tissue specificity(this is provided by the pattern line),they can be used by anyone who wantsto do a screen of this type. We plan tomake the lines available to all Droso-

phila researchers, and hope they will beused to address many different biologi-cal problems.

I, myself, am interested in using thescreen to study mechanisms of cell-typespecific gene expression. Imagine twocells with different identities in thesame organism, say a muscle cell and askin cell. These cells have the samegenomic DNA, yet express differentgenes. How is this achieved? We knowsome of the regulators (transcriptionfactors) that recognize specific DNAsequences and turn genes on and off.Surprisingly, some factors can recognizeand regulate different genes in differentcell types. I have been studying onesuch factor, called C/EBP, whichperforms several essential roles duringfly development. Based on a detailedanalysis of the C/EBP protein intransgenic flies, I concluded that thegenomic DNA itself may be imposingcell-type specificity on C/EBP.

This is not as strange as it sounds, foralthough the DNA is the same in eachcell of ;m organism, the chromatin intowhich it is Kumd is not. (There is no

"naked" DNA in a cell; it is all houndinto a highly complex protein-DNAlattice called chromatin). Intriguingly,it appears that chromatin's structurecan reflect earlier decisions of cellidentity and thus serve as a memory ofthese events. Perhaps it is this memory,in the local structure of a cell's chroma-tin, that directs the action of a trans-cription factor like C/EBP on theDNA. I will use the modular mis-expression screen to look for proteinsthat affect C/EBP's function or chroma-tin function in general, in order to gaina detailed understanding of how C/EBPinteracts with chromatin.

In conclusion, the modular mis-expression screen identifies geneswhich when over- or mis-expressed in apattern of interest give a specificphenotype or modify an existingmutant phenotype. This is a novel wayof finding genes with specific functionsin higher eukaryotes, and it is likely touncover new information. The modulardesign makes the screen simple to useand applicable to the study of manydevelopmental processes. Many usefulGal4 pattern lines are already available.Target lines are easy to generate andcan be used repeatedly, and mutatedgenes can be readily identified. The tactthat the screen has uncovered geneticinteractions which agree with moretraditional genetic analyses is strongsupport for its usefulness and relevancein studying biological processes inDrosophila. By using other transposableelements or retroviruses as indue iblemutagens, it is likely that similarapproaches may eventually be devel-oped for other organisms.

• •)•

• Personnel •Research Staff

Donald D. BrownChen-Ming Fan1

Andrew Z. FireJoseph G. GallMamie HalpemDouglas E. KoshlandAllan C. Spradling, Director

Staff Associates

Susan DymeckiPemille R0rthCatherine Thompson

Postdoctoral Fellowsand Associates

Joohong Ahnn, Research Associate, NIHGrant (Fire)

Michel Bellini, CIW2

Brian Calvi, Fellow, American Cancer SocietyOrna Cohen-Fix, International Human

Frontier Science Program FellowMaggie de Cuevas, Howard Hughes Research

AssociateSteve Farber, Fellow, Markey Charitable TrustShannon Fisher, CIW, Fellow of the NIHDavid Furlow, Research Associate, Mathers

Charitable Foundation (Brown)Vincent Guacci, CIWElizabeth Helmer, Research Associate,

Mathers Charitable Foundation (Brown)Akira Kanamori, Research Associate, NIH

Grant (Brown)3

William Kelly, Fellow of the NIHLinda Keyes, CIW, NIH Grant (Spradling)Mary Lilly, CIWJonathan Margolis, CIW4

Nick Marsh-Armstrong, Fellow of the JaneCoffin Childs Memorial Fund

Paul Megee, Cancer Research Fund of theDamon Runyon-Walter WinchellFoundation Fellow

Pamela Meluh, Fellow, Helen Hay WhitneyFoundation

Liz Mendez, CIWMary Montgomery, Fellow of the NIHMelissa Pepling, Howard Hughes Research

Associate1^

Amy Rubinstein, Research Associate, MarkeyCharitable Trust6

Alejandro Sanchez, Fellow of the NIHMichael Schlappi, CIW?Lynne Schneider, CIW8

Rob Schwartzman, Fellow, American CancerSociety9

Geraldine Seydoux, Research Associate,Markey Charitable Trust10

David Smith, Research Associate, MarkeyCharitable Trust11

Alexander Strunnikov, Research Associate,NIH Grant (Koshland)

Kathleen Wilsbach, Research Associate,Markey Charitable Trust

Chung-Hsiun Wu, CIW11

Zheng-an Wu, Research Associate, NIHGrant (Gall)

Ting Xie, Howard Hughes ResearchAssociate12

Ping Zhang, Howard Hughes ResearchAssociate11

Predoctoral Fellowsand Associates

Jennifer Abbott, Johns Hopkins UniversityDonna Bauer, Johns Hopkins UniversityDeborah Berry, Johns Hopkins UniversityKim Dej, Johns Hopkins UniversityHoracio Frydman, Johns Hopkins UniversityBrian Harfe, Johns Hopkins UniversityJenny Hsieh, Johns Hopkins UniversityHaochu Huang, Johns Hopkins UniversitySteve Kostas, Johns Hopkins UniversityCatherine Lee, Johns Hopkins UniversityValarie Miller, Johns Hopkins University

Supporting Staff

Betty Addison, Laboratory HelperKristin Belschner, Photographer (P.T)/Fiy

FoodPreparcr(BT.)Meg Bottcher, TechnicianEllen Caramon, Laboratory HelperPatricia Cammon, Laboratory HelperDuane Campbell, Fish Facility TechnicianPat Englar, Director's Administrative AssistantEugene Gibson, Custodian14

Stacey Hachenberg, TechnicianEileen Hogan, Senior Technician

YJ \¥ ft

Postdoctoral fellow Shannon Fisher

Mei Hsu, Technician15

Connie Jewell, PhotographerGlenese Johnson, Laboratory HelperSusan Kern, Business ManagerJeff Kmgshury, TechnicianBill Kupiec, Computer Systems ManagerJia Jia Mai, Technician1*Ona Martin, Senior TechnicianNoah May, Technician17

Ronald Millar, Building EngineerChristine Murphy, Senior TechnicianChristine Norman, Howard Hughes Medical

Institute Research SecretaryRohinette Oliver, Maintenance14

Irene Orfov, TechnicianAllison Ptnder, Research Technician IIIEirl Ports, CtisttxJianChris Puts, Secondary Animal Care

Technician^

Sheri Rakvin, Administrative AssistantBenjamin Remo, TechnicianMichael Sepanski, Electron Microscopy

TechnicianLoretta Steffy, Accounting AssistantDianne Stern, TechnicianDianne Stewart, Research Technician IIIJames Thomas, Principle Animal Care

TechnicianStanley Turner, Custodian19

Joe Vokroy, Instrument Maker/FacilitiesManager

John Watt, LibrarianTammy Wu, Technician20

Si'qun Xu, Technician

Visiting Investigators andCollaborators

Phil Beachy, Howard Hughes MedicalInstitute, Johns Hopkins University Schoolof Medicine

Igor Dawid, National Institutes of HealthStephen Ekker, Dept. of Biochemistry,

University of MinnesotaZandy Forbes, Dept. of Zoology, Oxford

University, Oxford, EnglandPhil Hieter, Dept. of Molecular Biology and

Genetics, Johns Hopkins UniversitySchool of Medicine

Phil Ingham, Imperial Cancer Research Fund,London, England

Michael Krause, National Institutes of HealthHaifan Lin, Dept. of Cell Biology, Duke

University School of MedicineAnthony Mahowald, Dept. of Molecular

Genetics and Cell Biology, University ofChicago

Gerald M. Rubin, University of California,Berkeley

Alexander Tsvetkov, Institute of Cytology,Academy of Sciences, St. Petersburg,Russia

Ted Weinert, Dept. of Molecular and CellBiology, University of Arizona

FTO;« A I

'TM Xfk ;

J>i ns S.'j

ivemKrr I, J4W5HUM 1, 1W5"iiiK'r *I7, 1*W*I

I'frtiik'f 1,H» |«WS

To N"To Fi;>T*> ^•To/'•Frni

^rton1 !• 19*^ovcrnhvr I,Km:mt k\ 1*1it Irtruury I, !\iipiHi U, 19

^Froiii IVcc•'From June'•From June{*From i\.tu:! 'Fr^tn April••Fiifiii fiine

mherl 19951, 19%

l*i 24, 1W17, 1996

1, 19%

• \

• Bibliography •Bauer, D. W., and J. G. Gall, Coiled bodies

without coilin, MoL Biol. Cell, in press.

Bellini, ML, J.-C. Lacroix, and J. G. Gall, A zinc-binding domain is required for targeting thematernal nuclear protein PwA33 to lampbrushchromosome loops, J. Cell Biol 131, 563-570,1995.

Basrai, M. A., J. Kingsbury, D. Koshland, F.Spencer and P. Hieter, Faithful chromosometransmission requires Spt4p, a putativeregulator of chromatin structure in Saccharo-myces cerevisiae, MoL Cell. Biol. 16, 2838-2847, 1996.

Brown, D. D., Z. Wang, J. D. Furlow, A.Kanamori, R. A. Schwartzman, B. F. Remo, A.Pinder, The thyroid hormone-induced tailresorption program during Xenopus laevismetamorphosis, Proc. Nad. Acad. Sci. USA93,1924-1929, 1996.

Cohen-Fix, C, J.-M. Peters, M. W. Kirschner,and D. Koshland, APC-dependent degrada-tion of Pdslp is required for the initiation ofanaphase in Saccharomyces cerevisiae, Genesand Devel, in press.

de Cuevas, M., J. K. Lee and A. C. Spradling, a-spectrin is required for germline cell divisionand differentiation in the Drosophila ovary,Development, in press.

Dymecki, S. M., Flp recombinase promotes site-specific DNA recombination in embryonicstem cells and transgenic mice, Proc. Nad.Acad. Sci. USA 93, 6191-6196, 1996.

Dymecki, S. M., A modular set of Flp, FRT andlacZ fusion vectors for manipulating genes bysite-specific recombination, Gene 171, 197—"201, 1996.

Forbes, Z., H. Lin, P. Ingham, and A. C.Spradling, hedgehog is required for theproliferation and specification of somatic cellsprior to egg chamber formation in Drosophila,Development 122, 1125-1135, 1996.

Forbes, Z., A. C. Spradling, P. Ingham and H.Lin, The role of segment polarity genes duringearly oogenesis in Drosophila, Development,122,3283-3294, 1996.

Furlow, J. D., D. L. Berry, Z. Wang, and D. D.Brown, Novel tadpole epidermis-specific genesare down-regulated by thyroid hormone duringmetamorphosis of Xenopus laevis tadpoles, Dev.Biol., in press.

Gall, J. G., Beginning of the end: origins of thetelomerc concept, in Telomeres* E. H.Blackburn and C. W. Greider, eds., pp. 1 — 10,

Cold Spring Harbor Laboratory Press, ColdSpring Harbor, New York, 1995.

Gall, J. G., A. Tsvetkov, Z. Wu, and C. Murphy,Is the sphere organelie/coiled body a universalnuclear component?, Dev. Genet. 16, 25-35,1995.

Halpern, M. E, C. Thisse, R. K. Ho, B. Thisse, B.Riggleman, B. Trevarrow, E. S. Weinberg, J.Postlethwait and C. B. Kimmel, Cell-autonomous shift from axial to paraxialmesodermal development in zebrafish floatinghead mutants, Development 121, 4257-4264,1995.

Halpern, M. E., Axial rnesoderm and patterningof the zebrafish embryo, American Zoologist, inpress.

Kanamori, A., and D. D. Brown, The analysis ofcomplex developmental programs: amphibianmetamorphosis, Genes to Cells 1, 429—435,1996.

Knotts, S., A. Sanchez, H. Rindt, and J. Robbins,Developmental modulation of a B-myosinheavy chain promoter-driven transgene, Dev.Dynamics 206, 182-192, 1996.

Koshland, D., and A. Strunnikov, Mitoticchromosome condensation, Ann. Rev. CellBiol 12,305-333, 1996.

Lilly, M., and A. C. Spradling, The Drosophilaendocycle is controlled by cyclin E and lacks acheckpoint ensuring S phase completion,Genes and Develop. 10, 2514-2526, 1996.

Mello, O, and A. Fire, DNA transformation,Methods in Cell Biology 48, 451-482, 1995.

Meluh, P., and D. Koshland, Evidence that theM/F2 gene of Saccharomyces cerevisiae encodesa centromere protein with homology to themammalian centromere protein, CENP-C,Mol Biol. Cell 6, 793-807, 1995.

Mickey, K. M., C. C. Mello, M. K. Montgomery,A. Fire, and J. R. Priess, An inductiveinteraction in 4-cell stage C. elegans embryosinvolves APX-1 expression in the signallingcell Development 122, 1791-1798, 1996.

Moerman, D., and A. Fire, Muscle: structure,function, and development, in The Nematode,C. elegans 11, D. Riddle, ed., Cold SpringHarbor Press, New York, in press.

Rtfrth, P., A modular misexpression screen inDnmphiki detecting tissue-specific phenotypes,

, Sad. Acad, Sci. USA 93, 12418-12422,

Saunder.% W. S., R Koshland, D. Eshel I. R.

Gibbons, and M. A. Hoyt, Saccharomycescerevisiae kinesin-and dynein-related proteinsrequired for anaphase chromosome segrega-tion, J. Cell. Biol 128, 617-624, 1995.

Seydoux, G., and A. Fire, Whole-mount in situhybridization for detection of RNA in C.elegans embryos, Me*. Cell Biol 48, 323-337,1995.

Seydoux, G., C. C. Mello, J. Pettitt, W. B. Wood,J. R. Priess, and A. Fire, Repression of geneexpression in the embryonic germ lineage ofC. elegans, Nature 382, 713-716, 1996.

Strunnikov, A- V, J. Kingsbury, and D. Koshland,CEP3 encodes a centromere protein ofSaccharomyces cerevisiae,]. Cell Biol. 128, 749—760, 1995.

Strunnikov, A. V, E. Hogan, and D. Koshland,SMC2, a Saccharomyces cerevisiae geneessential for chromosome segregation andcondensation defines a subgroup within theSMC-family, Genes and Devel. 9, 587-599,1995.

Talbot, W S., B. Trevarrow, M. E. Halpern, A. E.Melby, G. Farr, J. H. Postlethwait, T. Jowett,C. B. Kimmel, and D. Kimelman, Ahomeobox gene essential for zebrafishnotochord development, Nature 378, 150-157, 1995.

Thompson, C. C., Thyroid hormone responsivegenes in developing cerebellum include ahairless homolog and a novel synaptotagmin,J. Neurosci. 16, 7832-7840, 1996.

Tsvetkov, A. G., M. N. Gruzova, and J. G. Gall,Spheres from cricket and damselfly oocytescontain factors for splicing of pre-mRNA andprocessing of pre-rRNA, Tsitologia 38, 311—318, 1996.

Wu, C.-H. H., C. Murphy, and J. G. Gail, TheSm binding site targets U7 snRNA to coiledbodies (spheres) of amphibian oocytes, RNA2,811-823, 1996.

Yamamoto, A., D. B. DeWald, I. V. Boronenkov,R. A. Anderson, S. D. Emr, and D. Koshland,Novel PI(4)P 5-kinase homologue, Fablp,essential for normal vacuole function andmorphology in yeast, Mol. Biol. Cell 6, 525-539, 1995.

Yamamoto, A., V. Guacci, and D. Koshland,Pdslp is required for faithful execution ofanaphase in the yeast, Saccharomyces cerevisiae,]. Cell Biol 133,85-97, 1996.

Yamamoto, A., V. Guacci, and D. Koshland,Pdslp, an inhibitor of anaphase in buddingyeast, plays a critical role in the APC andcheckpoint pathway(s), J. Ceil Biol. 133, 99-110, 1996.

.IE ISSTiTlTK «S • YfcAR 95

yjfj&^t&nrrj/ lib;;; <^».r .'.'j&oifr \-£ •#***. IVV1

4||J(Jr

t:;: J; i'.ujit B a'i

, r -. *\ .. " rL?i!ci

r. C..: ;.T.:!.:

V ;• - *• ' i * -•••

v. f jr-*t row. Idt to nghi: Chrb Somerviiie, John Davies. Arthur Grossman.D*»J^ Hughes, AngefiQue Jackson. Johanna Pofsenberg. Second row: Claire'.1".". :/. IVoif^ng Lukcnvitz. Eva Huan^, Danja Schuenemann. Pierre Broun^'AV i:r. :n:;u t>i Gicnn). Marc Ni&himura. |u!ie O.sborn. Chrii Lund, Howard

ti^'^A', Vri:k*ria Canale. Robin Bueil. Kathi Bump. Cesar Bautisto,\. M.'^rt! O!r.^. Anne Rmxv. Paiti Pomdcxter. \ % n e Slochaj. Pinky

i;1, K:.s .\;us^;J^!n VV;ivi>n. Osamu Kishizaua, Neil Hoffman. Aidar IJC ^arn. Dav;J Kehoe {tar righi).

,#4

Director's Introduction

In order to understand a biological phenomena, it is frequently useful to firstidentify a suitable model. This concept is among the most important ofexperimental biology. It explains why populations of mice, flies, and other

organisms inhabit the laboratories of molecular biologists. One of those organisms,the single-celled yeast Saccharomyces cerevisae, has proved to be an exceptionalmodel for modern biology. This organism is particularly valuable in studies identi-fying the proteins and corresponding genes that control ubiquitous cellularprocesses. Saccharomyces has all of the basic machinery of a typical eukaryotic cell,as well as properties that facilitate the analysis of gene structure and function. It iseasy to maintain in the laboratory, and easy to manipulate. Indeed, the value ofthis organism for eukaryotic biology has been so profound that several years ago aconsortium of scientists from around

the world undertook to sequence its « T h e potential utiUty ofentire genome. In April of this year, ., i • , i • i, j i . , i easily cultivated single-

they announced the project s compie- ^ °

tion. As described in a recent review celled Organisms has notarticle in Current Biology (Vol. 6, pp. been hst on plant500-503), the roughly 15,000,000 base biologists...."pairs of DNA in Saccharomyces encode __________M-H-___--__«~*»»_-_.approximately 6,000 genes. Surpris-ingly, despite the intensive genetic analysis this organism has undergone over thepast twenty years, less than half of its genes had previously been identified bymutations. In some cases, the presence of two functionally redundant genes mayhave masked the effects of a mutation in one of the genes. In the majority of cases,however, the newly discovered genes are simply of unknown function. A newinternational collaboration is now underway to systematically mutate all of thegenes in yeast in order to assign function to each one. In preliminary experiments,many such mutations have no apparent phenotype in laboratory conditions, i.e.,they cause no change in the organism's appearance or behavior. Thus, it. seemslikely that much of the yeast genome is not required for cell viability but rather isused for adaptive responses to changing environmental conditions.

The potential utility of easily cultivated single-celled organisms has not beenlost on plant biologists. The green alga Chhmydinnonas reinhardtii, for example, has

been used as an important model forstudying aspects of plant biology,including photosynthesis, for more thanthirty years. Early work by Paul Levineand colleagues at Harvard Universityshowed that it waspossible to isolate andgrow large numbers ofChlarnydomonas

mutants unable to carryout photosynthesissimply by providing analternate carbonsource, such as acetate.Such mutants wereessential tools indissecting the series ofsteps involved inphotosynthetic elec-tron transport. Unfor-tunately, Chhmydorno"

nas proved to berecalcitrant to genetictransformation withexogenous DNA (i.e.,it was not possible tointroduce genes), andthe early plant molecu-lar biologists frequentlybypassed it in favor ofother organisms thatcould be transformed.However, a few re-searchers. Including CamegieV ArtGrossman, persevered. Several yearsago, the transformation problem wasresolved, and if is now routinelypossible to introduce exogenous DNAinto the Chlamy&ommas genome atrandom sites. Because CMamydanumas

k normally haploid* the insertion ofexogenous DNA frequently disrupts a^ene. By transforming with a well*JeftneJ source of DNA, such ass a

bacterial plasmid, disrupted genes caneasily be found (and later cloned) byvirtue of their association with theplasmid.

In their essay on p. 99, Kris Niyogi,Art Grossman, andOlle Bjorkmanexplain howChlarnydomonas

mutants are provid-ing new insightsinto a problem oflong-standinginterest to theBjorkman labora-tory—the dissipa-tion of excess energyas heat. Over thepast decade, Olleand others haveaccumulatedabundant physi-ological evidencesuggesting thatpigments calledxanthophylls play akey role in dissipat-ing the excessenergy produced bylight absorptionduring photosynthe-sis. However, muchof the evidence

implicating the xanthophyll cycle hasbeen indirect. Furthermore, it wasunclear what other processes, if any,contributed to the energy dissipationprocess. By screening for insertionalCbkmydommas mutants that aredefective in photochemical quenching(which provides a measure of theamount of energy dissipated as heat),Kris, Art, and Olle are dissecting theprocess with unprecedented detail

Chlamydomonas

The genetic approach will eventsally reveal the different kinds andamounts of gene products involved inthe overall process. Since the disruptedgenes can be cloned, and, in manycases, identification of the gene productdeduced by sequencing, it should bepossible to define the precise functionof each component. Although muchremains to be done, the initial isolationand characterization of Chlamydomonasmutants has demonstrated that addi'tional mechanisms, besides the xanthophyll cycle, contribute to the dissipa-tion of excess light energy. Consideringthat plants cannot control the amountof sunlight they receive, it is hardlysurprising that they have developeddistinct processes with redundantfunctions to cope with the potentiallylethal effects of too much light.

Looking back, we may envision thefirst moment several decades ago whenOlle Bjorkman stood in Death Valleyand was struck with the question ofhow plants were able to survive theblazing sun. Much can be learned aboutthe nature of biological research—andthe use of model systems—by consider-ing the path that led from that firstmoment of curiosity to the currentwork on gene identification in Chlamy-domonas.

The importance of models is alsoevident in Chris Field's essay explaininghow increasing atmospheric CO2

concentration is likely to affect natural

ecosystems. Because of the high cost oflong-term CO2 enrichment experi-ments, it is necessary to expose plantsto CO2 in relatively small enclosedareas. The complexity of the responsesobserved in Chris's model containmentsystem reveals some of the principlesthat will guide current and futurethinking about the consequences ofincreased CO2 concentration.

Chris's results show that in additionto changes caused by the climaticeffects of increased CO2, we may expectaccompanying changes in the speciescomposition of natural ecosystems.These changes result from direct andindirect biological effects of increasedCO2 on water use efficiency andphotosynthesis. I consider the resultsobtained by Chris and colleagues to bealarming. As we continue to makemassive alterations to the ecosystem (byour land and water use practices), itseems we will face as yet unknownalterations in the species balance of theremaining undisturbed areas. It appearsunlikely that we will be able to curbCO2 emissions in the foreseeable future.Indeed, it is very hard to imagine thatanything can be done on a largeenough scale to have a remedial effect.Perhaps our best hope is that ourincreasingly sophisticated ability tomanipulate plants genetically willeventually permit us to develop plantswith much higher rates of CO2 assimi-lation.

— Christopher Somervilk

Photo, next page: Carnegie^ gigantea cacti near the site of Carnegie's former Desert laboratory in Tycson,Arizona. How these ami other plants avoid damage to their photosjethetlc apparati in high light remains anactive area of research at the Department of Plant Biology.

How Plants Protect Themselves fromDamage by Excessive Sunlight

by Krishna Niyogi, Arthur Grossman, and Oik Bjorkman

Over the course of days and seasons, plants experience large variations inthe amount of sunlight they receive. Much of the radiant energy isabsorbed by light-harvesting complexes in the photosynthetic (or

thylakoid) membranes of the chloroplasts. The light-harvesting complexes arecomposed of a family of proteins bound to chlorophyll and the carotenoids (acces-sory orange and yellow pigments such as lutein, zeaxanthin, and (3-carotene). Theenergy absorbed by the pigment-protein complexes drives photosynthetic electron

Plants dissipate much oftheir excess energy as

heat. Insights frommolecular biology are

helping scientists learndetails of this

photoprotective process.

transport, which converts light energy intochemical energy in the form of ATP andNADPH; these molecules are required to fixatmospheric CO2 into sugars and otherorganic molecules upon which the plant'slife—and ultimately our own lives—depends.

For the past several years, research in theBjorkman laboratory has focused on questionsrelating to how environmental parameters,such as light intensity, alter the way in whicha plant uses incident light energy. Regulationof light energy is critical for balancing the production and metabolic consumption(by photosynthesis) of chemical energy. In low light, plants increase their capacityfor light harvesting by making larger light-harvesting complexes, allowing them tomaximize photosynthetic efficiency- As the intensity of light increases, however,the rate of capture of radiant energy exceeds the capacity for which it can be used;photosynthesis becomes saturated not because of a limitation in light absorptionbut because of a limitation in light energy utilization. The level of light intensityat which photosynthesis reaches a maximum is influenced by such factors as

Krishna Niyogi has been a postdoctoral fellow inArthur Gross man's laboratory (and also OlleBj.6rkman*s. lab) since 1/993,. when lie finished hisPti,lX (h\ biology) at MIX. He is keenly interested Inthe regulation and photoproteettcm of photosynthesis.

Yr \k \ *k 95 • C

temperature, salinity, and water avail-ability. Under unfavorable growthconditions, the plant will experienceexcessive light even at relatively lowintensities.

fluorescence

heat (NPQ)

Figure 1. Pathways for dissipation of light energyabsorbed by chlorophyll. Absorption of sunlightcauses chlorophyll (Chi) to enter the singlet excitedstate (Chi*), It then releases that energy In one offoor ways: through photochemistry, NPQ,fluorescence, or by generating the toxic singlet

Dissipating Energy as Heat

When the input of radiant energyexceeds a plant's capacity to use it, thephotosynthetic apparatus may bedamaged. Excess light may lead to theproduction of dangerous pigment andoxygen species that can react promiscu-ously with numerous chloroplastcomponents. For example, whenexcitation energy accumulates in thelight-harvesting complexes, tripletchlorophyll may form. This moleculereacts with molecular oxygen togenerate highly reactive singlet oxygen,a toxic radical. Although plants havesome capacity to cope with oxidativedamage, they are generally able todissipate much of the excess lightenergy safely as heat before toxicradicals form.

Plants dissipate heat through amechanism called nonphotochemicalquenching (NPQ). When a chlorophyllin the light-harvesting complexesabsorbs a photon of light, an electronbecomes excited, and the chlorophyllenters the energized singlet excitedstate. It can return to the ground stateby one of the four routes depicted inFigure L It can transfer its excitationenergy to another chlorophyll moleculeand ultimately to the photosyntheticreaction centers to drive photochemis-try (1). The chlorophyll can dissipateits excitation energy as heat through

Arthur R* Grossman eatwtee! an M.*8* and a PiuD. from.-Indiana Uaivtwity and Jcwied Carnegie In 1982* one of thefirst stall' ntcmiiers to he mtilectttarly ©iicistccL His majorJiifcrtst lies is leatttittg itiiw pluitosvntlictic offpitiistiissense and respond to changes- in, •apvirciciniettfal conditions*iiiili';its li|hflaiefisif:f •tin! ^itt i lt i^ IIIKI nutrient availability*

• Yi v fi

NPQ (2). It can release the energy asfluorescence (light energy of a longerwavelength) (3). Or, the singlet excitedchlorophyll may drop to the tripletexcited state, which then can return tothe ground state after interacting withoxygen to generate the toxic singletoxygen molecule (4). The first routeprovides energy for photosyntheticelectron transport and the generationof sugars. The second and third path-ways are harmless dissipative processes.The last pathway has the potential todamage the photosynthetic reactioncenters and destroy many molecules inthe cell.

NPQ is photoprotective in partbecause it provides an effective alterna-tive to the de-excitation of chlorophyllvia the hazardous triplet pathway.However, NPQ also competes withphotochemistry, so it must be strictlycontrolled to minimize any loss inphotosynthetic efficiency atsubsaturating light intensities. We areinterested in determining the mecha-nisms which trigger NPQ, and identify-ing the molecules critical for theprocess.

We can determine NPQ by measur-ing changes in chlorophyll fluores-cence. Although the amount of energyemitted as fluorescence is generallysmall (at most 3-4% of the absorbedenergy), fluorescence provides aconvenient visual indicator of the

energy dissipated as heat, which can bevery significant—up to two-thirds ofthe absorbed light energy. When heatdissipation increases, chlorophyllfluorescence decreases, i.e., it isquenched, hence the origin of the termnonphotochemical quenching.

Numerous biochemical and physi-ological studies suggest that the pHwithin the aqueous lumenal space ofthe thylakoid membranes plays a keyrole in establishing NPQ. Photosyn-thetic electron transport is accompa-nied by the movement of protons(hydrogen ions, H+) across the thyla-koid membranes, which generates adifferent pH on either side. This protongradient, or ApH, is the stored energythat is harnessed (by the enzyme ATPsynthase) to make ATP. In the processof forming ATP, the gradient is dissi-pated. However, when light harvestingand electron transport exceed thecapacity of CO2 fixation and otherenergy-assimilating reactions, ATP isnot consumed fast enough to liberateADP (the precursor to ATP) for theATP synthase. As a result, the magni-tude of the ApH increases, and thelumen becomes more acidic. Thischange in pH serves as an indicator ofexcessive light and triggers NPQ.

Several years ago, workers elsewherenoted that changes in NPQ wereaccompanied by changes in the con-centrations of particular carotenoid

Born and educated in Sweden (where he earned his doctor'ate at the University of Uppsala), Olle Bjdrfcman lias beenwith Carnegie since 1964- His biochemical studies on plantadaptation, have taken him to environments- ranging fromDeath 'Valley to the tropical irotsties of Australia.

jft\'K

Figure 2. Fluorescence imaging of Chlamydomonascolonies. NPQ. mutants are shown among progeny of agenetic cross between the mutant and the wild type.Mutant colonies with reduced NPQ.appear black,whereas wild-type colonies appear white. The mutantphenotype segregates 2:2 in each tetrad (column offour colonies) produced by meiosis, indicating thatihe phenotype is due to a single Mendelian mutation.

pigments called xanthophylls. Thesemolecules, integral to the photosyn-thetic membranes, are derived from P-carotene and a-carotene. The keyxanthophylls thought to be involved inNTQ—zeaxanthin (Z), antheraxanthin(A), and violaxanthin (V)—arederived from P-carotene. The forwardand reverse interconversion of Z, A,and V is called the xanthophyll cycle.V is converted to A and Z when theApH i 4 the thylakoid membranesreaches a critical magnitude, i.e., whenthe plants are exposed to too muchhtfht.

Subsequent work in the Bjorkmanlab has contributed to what is now alarge Kdy of evidence demonstrating astrong; correlation between the concen-rratit^n of Z and A .ind the extent of

NPQ. In particular, inhibitors of Z andA formation can greatly decrease NPQ.Recent work from the laboratories ofThnnu* iVtvens (Cornell University)md H;ur\ Frank tL'nsverMtv iiKxtKiit \ ht\* ^hnun that Z, andperhaps A\M* A, are theoretically

capable of directly de-exciting singletexcited chlorophyll, providing abiophysical basis for NPQ.

Clues from Molecular Biology

A couple of years ago, we in theBjorkman lab began a collaborationwith the Grossman lab, exploring howgenetic and molecular biologicalapproaches might help us understandthe mechanisms that contribute toNPQ. For this work, we are using thesingle-celled green alga Chlamydomonas

reinhardtii. Chlamydomonas performsphotosynthesis in a manner essentiallyidentical to that of vascular plants, butunlike vascular plants, Chlamydomonas

is able to grow without photosynthesis.It can use acetate as its sole carbonsource. This characteristic makesChlamydomonas an advantageousexperimental subject, since mutantsthat are unable to carry out photosyn-thesis can be maintained on acetate-containing medium. (Chlamydomonas

mutants of this type were used overthree decades ago to define the pathwayof photosynthetic electron transport.)In addition, Chlamydomonas is anexcellent organism for genetic studies;it has a well-defined sexual cycle, apredominant haploid generation thatfacilitates the isolation of recessivemutations, and it is readily transformedwith exogenous DNA.

Kris Niyogi has isolated and charac-terized several mutants defective inNPQ, using a mutagenesis technique inwhich a piece of DNA of knownsequence is inserted into a genome.The mutant organisms were then grownas colonies in petri dishes. When theyreached sufficient numbers, they were

exposed simultaneously to excessivelight for a ten-minute period. (Thisallowed us to determine which of thecolonies were deficient in NPQ.) Wecaptured fluorescence images by videocamera, digitized the images with acomputer, and calculated the extent ofNPQ. As seen in Figure 2, the darkcolonies had higher fluorescence andthus reduced NPQ, while the lightcolonies had normal NPQ.

To determine how NPQ and thexanthophyll cycle were related in theNPQ-deficient mutants, we measuredlevels of chlorophyll, carotene, andxanthophyll after again exposing themutants to high light (Fig. 3). The

wild-type strain (upper left) showed thenormal complement of xanthophylls,including Z and A produced from V viathe xanthophyll cycle. (The othercomponents of the "pie" are identifiedin the legend.) The strain designatednpql (bottom left), one of the mostinteresting mutants we isolated, wasunable to convert V to Z and A uponexposure to excessive light. (Likely,npql is defective in the enzyme thatcatalyzes this reaction.)

That the npql mutant was unable toproduce Z and A confirmed suggestionsfrom earlier experiments that Z and Aare involved in NPQ. However, asignificant amount of NPQ—about

Lor

Lut

npql Lor

tori

H

Figure 3. Pigment composition of wild type (upper left) and three mytants of Chlamydornonas. All cyltoreswere exposed for 40 minytes to a light intensity equivalent to 25% of full sunlight Nxneaxanthtn,Vavfolaxanthin, A«antheraxanthln, Z^zeaxanthin. Lut«lutein. Lor»toroxanthm. aC and pC * oc-carotenc andp-carotcne, respectively. |See text for explanation.)

Figure 4. Growth of wild type and three mutants of Chlamydomonas under a light intensity eauivalent to 5%(left) and 25% (right) of full sunlight.

two-thirds of that in the wild-type—was still observed in the mutant. Thisseemed inconsistent with the premisethat Z and/or A are absolutely requiredfor NPQ. Furthermore, we were sur-prised to find that the npql mutantexperienced no more sustainedphotodamage than wild-type Chlamy*

dumonas upon short-term exposure tohigh light. In long-term growth experi-ments, too, npql seemed to have nogrowth defect in high light comparedwith wild type (Fig. 4), despite the factthat the regulatory process of NPQ wasperturbed. One possible explanation forthese results is that a remaining capac-ity for NPQ in the npql mutant issufficient to permit normal growth inexcessive light. This implies that thereis mure than one way to generate NPQ,which is not surprising given itsecological importance. It also impliesthat there are components in the light*harvesting complex other than A and Zthat are critical fur the normal opera-tion of NPQ in high light.

We hypothesized that other xantho-phvlls pren.*nt in the photosyntheticmemhrime* ot Chkmydomnnas, besidesVT A. and Z, might hv re*»pomable forthe NPQ observed in the npq! mutant.

In particular, we suspected that thexanthophylls lutein (Lut) andloroxanthin (Lor), both derived froma-carotene, were likely candidates, asboth are similar structurally to Z and A.In addition, the available informationconcerning the energetic properties ofLut and Lor suggested that one or both,like Z and A, have the potential toquench excitation energy in the light-harvesting complexes by direct interac-tions with chlorophyll.

We tested this hypothesis by againusing genetics, taking advantage of anexisting mutant of Chlamydomonas,

called lor J, that is unable to make a-carotene, Lut, and Lor, but can synthe-size large amounts of Z and A via thexanthophyll cycle (Fig. 3C). Uponexposure to high light, the lor 1 mutantexhibited substantially less NPQ thanwild type, but like the npql mutant,hrrl was able to grow in high light (Fig.4, lower left). A very exciting result wasobtained when we crossed the lor I andnpql mutants to generate the doublemutant. This strain has no cc-carotene,Lnt» or Lor, and only small amounts ofZ ;tnd A (Fig. 3D). Because of a severeJefect in NPQ, it is unable to survive inhigh light, whereas growth in low light

(subsaturating with respect to photo-synthetic electron transport) is normal(Fig. 4).

Future Studies

These genetic experiments usingChlamydomonas have provided the firstevidence that xanthophylls derivedfrom both p-carotene and oocaroteneplay critical roles in establishing NPQand in controlling the use of lightenergy. They also strongly suggest thatthere is some functional redundancy inphotoprotection; that is, the (3- and a-carotene derivatives seem able, at leastpartially, to substitute for one another.Future studies will address severalremaining questions. For example, arethe xanthophylls acting directly orindirectly to facilitate dissipation ofexcitation energy as heat? It seemspossible that the lack of particularxanthophylls in our mutant strains wasthe result of an indirect effect, perhapsa structural perturbation of the light-harvesting complexes. Examination oflight-harvesting complex assembly andstructure in the mutants will addressthis point.

Another question involves location.Where in the light-harvesting com-plexes are the xanthophylls located,and what are precise functional interac-tions among xanthophylls,chlorophylls, and the light-harvestingproteins? Characterizing NPQ mutantsthat exhibit normal xanthophyllcomposition, i.e., those with mutationsin some other part of the energy-dissipation process, and isolating thegenes affected in these strains mayprovide us with some answers.

A final question relates to the

[ft

I*/

"V*

• -X'*

Figure 5. Screening for NPCImutants in Arabidopsis.A mutant appears black among a large number ofnon-mutant plants (light gray).

generality of our results. To what extentare experiments with the unicellulargreen alga Chlamydomonas applicable tothe process of NPQ in vascular plants?We have recently initiated mutantanalyses with the vascular plantArabidopsis thaliana, which is currentlythe most popular and powerful modelplant system. Like Chlamydomonas,Arabidopsis possesses numerous charac-teristics that make it an excellentgenetic organism; it has a small nucleargenome with few repetitive DNAsequences, a dense genetic map and adeveloping physical map of the ge-nome, a database containing manythousands of expressed sequence tags,and the likelihood that the completesequence of the genome will be avail-able in just a few years. In preliminaryexperiments, we used our fluorescencevideo system to isolate Arabidopsismutants with reduced NPQ (Fig. 5).Two of these mutants are unable tomake Z and A during exposure to highlight. During the next year we plan toundertake detailed characterizations ofthese mutants to gain further insightsinto the mechanisms that allow photo*synthetic organisms to survive aconstantly changing light environment.

Ml

The Changing Carbon Cycle,from the Leaf to the Qlobe

by Christopher Field

Much of the discussion concerning carbon dioxide (CO2) and globalchange has focused on CO2 and climate. Yet, CO2 has important directeffects on plants. At least in the short term, increased CO2 leads to

increased photosynthesis and decreased water loss (through small pores, or sto-mata, on the surface of the leaves). If these effectspersist after long-term exposure to increased CO2,and if they are not suppressed by other factors at theecosystem scale, they could have dramatic conse-quences. Plants could grow bigger, faster, and use lesswater, leading to increased production of food, fuel,and fiber, and increased farming of arid lands.Increased CO2 uptake by plants could also removesome of the carbon injected into the atmosphere byhuman activities, especially fossil fuel combustion.Should this occur, the rate of increase in CO2

concentration in the atmosphere may slow down,decreasing the need for costly societal changes toreduce CO2 emissions. » • « _ _ « _ _ _ _ _ _ _ • _ • .

However, this bright picture darkens significantlywhen one considers that CO2 atmospheric concentration has already increased byover 25% since the beginning of the industrial era. Strong evidence suggests thatterrestrial ecosystems currently sequester 20—30% of the carbon released by humanactivities. Will plants and soils reach a saturation point where they can store nomore carbon I

Global change is subject to large unknowns. The seemingly positive, direct

What happenswhen plants areexposed to excesscarbon dioxide?Department ofPlant Biology

workers find thatthe availability ofwater is a critical

factor.

\ Chris Pieicl .earned his B.S* si Harvard and his Pli.P* at< Stanfo&d* 1:0: 1:984, after teaching at the University ofi •Utah for several years* lie came &> the Department of

I Pifiit Biology .as a staff inenibet*, There, lie participates

if lit ".'•>; 'Jif in sfudBes exploring biodiversity and evolution* and

ft, 1

effects of elevated CO2 are complicatedby a host of indirect effects. Some ofthese indirect effects amplify the directeffects, but others may suppress them.In addition, effects that are beneficialfrom one perspective may be detrimen-tal from another. For example, a CO2-stimulated increase in plant growthcould be a benefit if the stimulatedspecies were economically or ecologi-cally valuable. But it could be a seriousproblem if the stimulated species wereweeds. Overall, our understanding isincreasing rapidly, but it is still tooincomplete to support accurate predic-tions across a broad range of ecosystemsand over the whole suite of direct andindirect mechanisms.

My lab is exploring these issues at anumber of scales, ranging from singleplants, through whole-ecosystemexperiments, to global models. Theobjective of all these studies is toidentify mechanisms that have notbeen fully explored, quantify theirimpacts, and clarify their interactions.We are striving for an understandinggeneral enough to be relevant to all theworld's ecosystems, across tremendousvariation in climate, soils, and speciescharacteristics. We still have a long wayto go, but more and more of the piecesare in place.

Ecosystem-Scale Responses toIncreased CO2

The literature on plant responses toelevated CO, contains thousands ofpapers. Most of these concern agricul-tural species grown as individuals inpots, with abundant light, water, andmineral nutrients. For the goat ofdeveloping a general understanding,

these studies are of limited use. Theplant species studied are too similar intheir growth characteristics and climaterequirements. Each experiment is tooalike to assign causality for the differ-ences among results. And relatively fewstudies address mechanisms at levelsabove the scale of the individual plant.

A relatively small fraction of theCO2 literature concerns wild plants,and an even smaller fraction concernswhole ecosystems. Yet, several processesat the ecosystem level have the poten-tial to dominate the responses of theterrestrial biosphere to increasing CO2.Some of these involve species effects. Inmixed communities, for example,species that are more CO2 sensitive maybe more successful in a CO^enrichedenvironment and become dominant,creating a total response greater thanthat averaged across species. Otherprocesses concern environmentalfactors limiting plant growth. It isn'tclear if nutrient or water limitationwould restrict the actual growthresponses to increased CO2, or ifelevated CO2 would allow plants tocope more successfully with stressfulhabitats. And some of the most inter-esting processes involve interactionsamong aspects of the CO2 response. Forexample, extra carbon in the soil (asplant litter) could stimulate microbialactivity, which could release morenitrogen from decaying plant material.On the other hand, litter from plantsgrown at high CO2 may be moreresistant to microbial decay, slowingnitrogen release. Experimental access tothis kind of ecosystem-scale process iscritical in evaluating the relativeimportance of mechanisms with verydifferent outcomes.

^J&#&X% .", *

One of the open-top chambers of the Jasper RidgeCO2 experiment with the Stanford campus in thebackground. During the spring, this grassland is arich carpet of blooming wildflowers.

In 1992, my lab started ecosystem-scale CO2 experiments on StanfordUniversity's Jasper Ridge BiologicalPreserve, about five miles from theDepartment of Plant Biology. Theseexperiments are a collaboration withgroups from Stanford, the University ofCalifornia at Berkeley, and the Na-tional Center for Atmospheric Re-search, with inputs from researchers at anumber of other institutions. The ideais to use an annual grassland ecosystemas a model for probing ecosystem-scaleCO2 responses. Our working hypothesisis that the underlying principles weuncover by studying and manipulatingthis ecosystem will provide a soundbasis for predicting the response ofother ecosystems to increasing atmo-spheric CQ2.

Just as a biological model likeArahidopsis provides unique opportuni-ties in plant genetics and molecularbiology, annual grasslands provideunique opportunities in ecology. Like

other model systems, the Jasper Ridgegrasslands operate with very generalmechanisms, and experiments based onthem are efficient in terms of space,time, and expense. Key advantages ofthese grasslands are the annual habit(allowing us to study entire genera-tions), the small size of individualplants (allowing us to study a reason-ably complete ecosystem in a smallspace), and the high species diversity.Also, the close juxtaposition of grass-lands on very infertile and moderatelyfertile soils at Jasper Ridge helps insurethat we are not confusing ecosystem-specific patterns with general patterns.

The leaf-level responses to doubledCO2 we observe in our Jasper Ridgeexperiments are typical of many plants.When the soil is moist, elevated CO2

leads to a 30-70% decrease in plantwater use and a 20-40% increase in netphotosynthesis. As the soil dries at theend of California's winter-spring rainyseason, the differences are even greater,with net photosynthesis in the el-evated-CO2 plots up to twice as high asit is in the low-CO2 plots. This is be-cause soil moisture reserves are higherin the elevated-CO2 plots.

To understand this effect, ChrisLund, a Stanford Ph.D. student in mylab, has conducted careful studies ofCO2 effects on the water budget of theplants. He finds that doubled CO2

increases by up to 100 mm the waterstored in the soil. The extra waterallows some plant species to extendtheir growing season by several weeks.The effect is greatest in experimentswith relatively fertile soil, wheretranspiration from leaves (and notevaporation from the soil) controlswater loss.

10s C \E\b .31 TIOS • YEAR BOOK 95

Increased soil moisture in the high-CO2 plots at the end of the growingseason has a number of importantconsequences. Only some of the JasperRidge annuals are physiologicallycapable of using the extra waterreserves. Most of the species follow adevelopmental schedule stronglyregulated by daylength. By floweringand setting seed before the soil droughtbecomes too severe, these species canminimize the probability of a catastro-phic failure to reproduce. However,they miss the opportunity to use theextra water resources. The species thatare physiologically competent to use theextra water resources include twoimportant groups. One group that takesdramatic advantage of the extra water isthe native, nitrogen-fixing annuallegume Lotus wrangelianus. BecauseLotus grows much bigger, it fixes muchmore nitrogen under increased CO2.Concentrations of 15N in tissues ofLotus and other species suggest that atleast some of this extra nitrogenbecomes available to other species,providing an indirect benefit fromthe increased CO2 .

Another group of plants thatresponds positively to the extramoisture at the end of the growingseason are the long-lived annuals,which reproduce during the summeror autumn, after living for up to ayear. Most important among them arethe native tarweeds, which are sticky,coarse, almost woody plants. Theirdominance under elevated atmo-spheric CO : conditions suggests thatthe character of the Jasper Ridgeecosystem might change dramaticallyin such an environment, fromgrasslands and wildflower fields to

something more like a weed patch in avacant lot.

The results also suggest some generaltrends that may be broadly important,and that we are now preparing to test.One is that increased CO2 may gener-ally favor the invasion into grasslandsof deeply rooted species able to capital-ize on the increased soil moisture. Ingeneral, moisture availability is acritical controller, along with fire andgrazing, of the boundaries betweengrasslands and shrublands or forests. Ifincreased CO2 favors woody vegetation,fundamental changes may occur overvast areas, eventually leading to asevere decrease in grassland ecosystems.Another possible trend is suggested bythe success of Lotus under doubled CO2

A number of simulation models indi-cate that long-term ecosystem CO2

response is very sensitive to changes inthe total nitrogen. If nitrogen-fixers ingeneral are more stimulated by CO2,

Former Carnegie Ph.D. student Missy Holbrook (nowon the faculty at Harvard University) measures plantwater stress as a test for effects of elevated CO2 soilmoisture.

w<:£ V 4-|*

109

Former research assistant Julie des Rosiers (right) and research associate Susan Thayer record the abundance

of late annuals during the California summer.

then limits on plant growth fromnitrogen availability may be much lessimportant than we currently estimate.

Microbial processes are also verysensitive to CQ:-induced changes insoil moisture. Work by Bruce Hungate(who worked on the Jasper Ridge CO2

experiment as a Ph.D. student at theUniversity of California, Berkeley)suggests that doubled CO : leads to anincrease in the rate at which microbesrelease nitrogen into the soil, and aconcomitant increase in plant nitrogenuptake. The latter result was a surprise,because microbial biomass also in-creases, and microbes often outcompeteplants for nitrogen. The explanationmay lie in how CO, affects the compo-sition of the microhial community. Itappears that elevated soil moistureunder di iubled € O : allows an increase111 the number of protozoans, whichprev on the bacteria that would nor-mally compete with the plants foravailable nitrogen. Whether or not thisresponse is general, it clearly highlightsthe potential importance of speciesinteraction's, and of ecosystem playersbewnd the Joinmant plants.

The )a?»pt*r RiJ^e CO# experimentsutwMentK iJentit\ water, md howplan?*, ro-spi-iul to water, as A critical

component of the large-scale, long-termresponse to increased CO2. Othercomponents, including species charac-teristics and soil fertility, are importantas well. Across the world's grasslandecosystems, species composition andchanges in nutrient cycling will mostlikely control the major responses.

CO7 Responses at theQlobal Scale

Most studies on the effects of CO2

and climate use general-circulationmodels to evaluate the consequences of

CO2 as a greenhouse gas. (A green-house gas traps solar energy andprevents it from being radiated to space;as a consequence, the atmosphere isheated and radiates back to Earth.)Building from our experience at JasperRidge, where effects of doubled CO : onthe water budget loomed so large, mycollaborators and I decided to explorethe climate implications of decreasedwater loss (through stomatal conduc-tance) induced by elevated CO : . Inexperiments with increased CO2, leaftemperatures are often elevated,sometimes by a degree or more, aspartial stomatal closure forces a de-crease in the amount of energy used to

• V-

evaporate water. Because the canopymust dissipate as much energy as itabsorbs, it compensates for the decreasein evaporation by transferring moreheat to the air. As a result, canopytemperatures increase.

Is this effect important at the globalscale? We are exploring this questionusing a model of the terrestrial bio-sphere developed by Piers Sellers(NASA's Goddard Space Flight Cen-ter) and others, including Plant Biologystaff member Joe Berry. (Sellers hassince become an astronaut in training.)Coupling Sellers' model to an atmo-spheric general-circulation modeldeveloped by Dave Randall andcolleagues at Colorado State Univer-sity, we examined changes in surfacetemperatures with greenhouse warmingand stomatal warming resulting fromdoubled CO2. Our simulations sug-gested a substantial magnitude forstomatal warming, more than 1 ° inmid-continental locations (Fig. 1).While smaller than the greenhousewarming, the stomatal effect willincrease the overall impact of elevatedCCX on climate.

With these simulations, we startedwith an experimental observation atthe local scale, tested its implications

Postdoctoral fellow Yioj tuo(left) measures soil respira-tion on an experimentalecosystem growing underelevated CO, conditions, asPh.D. student Jim Randersonrecords plant density.

with a sophisticated model, and arenow returning to experiments for aclearer picture of the effects that needto go into the model. Hopefully, acontinuing dialog between local-scaleexperiments, local-scale models, andglobal-scale models can provide afoundation for narrowing the uncer-tainty about future global changes.

Biological Interactions andIncreased CO2

A few experimental studies withelevated CO2 have examined how CO2

might affect interactions betweenplants and their predators. Others haveexplored how CO2 might affect thesuccess of an invading plant species.But most studies, even those at theecosystem level, exclude such poten-tially important biological interactions.Carolyn Malmstrom, a Stanford Ph.D.student in my lab, recently undertooksome of the first studies on a set ofbiological interactions involving plantsand their pathogens.

Carolyn studied how increased CO :

might afteet the impact of BarleyYellow Dwarf Virus (RYDV) on oatsArena SUUWL Since RYDV is transmit-ted only through aphid infestations, and

• I'v.

is not carried in the germ line, Carolyncould regulate infection by controllingaphid treatments, and she couldconfirm the infection immunologically.(Because an aphid infestation haseffects beyond transmitting the virus,Carolyn assessed the impacts of viralinfection bycomparing herplants to thosebriefly infested withnon-BYDV-infectedaphids.)

BYDV is gener-ally nonfatal, but itdecreases plantgrowth by disrupt-ing the movementof carbohydrate outof leaves throughthe phloem. This isa potentially largeproblem, becausecarbohydrate exportis the fuel forproducing otherplant parts, includ-ing grain. Twopossible scenariosexist for interac-tions betweenBYDV and elevatedCO2. Underincreased CO?,BYDV infectioncould disrupt themechanisms by

-2

change in temperature (°C)

Figure I. Simulated changes in surfacetemperature as a function of latitude for theworlds land points in |ujy, plotted relative tomodel simulations with ambient CO2 (dottedline). Effects of greenhouse warming are shownas the solid purple line, stomatal warming (witha relatively large effect of CO2 on conductance)as the dashed purple line, and the combinationof both mechanisms as the black line. {Redrawnfrom Sellers et al. Science 271, 1402-1405.)

which the leaves

distribute carbohydrate even more, andthus have a larger negative impact onthe growth and grain production. Or,

the increased carbohydrate from theelevated CO2 could essentially over-power the BYDV blockade.

In Carolyn's experiments, doubledCO2 led to greater growth in bothvirus-infected and uninfected oats, butthe relative stimulation was greater in

the virus-infectedplants. The virus-infected plantsresponded toincreased levels ofleaf carbohydratewith increasedtransport. In thisway, increased CO2

helped infectedplants tolerate theirinfection, whichwould lead todecreased overallyield losses. At thesame time, in-creased CO2 mightincrease the numberof infected plants byproviding theaphids with largertargets for infection-While we have yetto quantify thebalance betweenthese two compo-nents, it is clear thatCO2-pathogeninteractions canhave major impactson ecosystem

function. Our predictive models will beincomplete until they account for theseinteractions.

• Personnel •Research Staff

Joseph A. BerryOlle E. BjorkmanWinslow R. Briggs, Director EmeritusChristopher B. FieldArthur R. GrossmanNeil E. HoffmanChristopher R. Somerville, DirectorShauna C. Somerville

Visiting Investigators

Mark Stitt, University of Heidelberg,Germany1

Kosuke Shimogawara, Teikyo University,Tokyo, Japan2

Simon Turner, University of Manchester, UK3

Osamu Nishizawa, Kirin Brewery Co, Ltd.

Postdoctoral Fellows andAssociates

Luc Adam, National Science Foundation(NSF) Research Associate

Kirk Apt, Martek FellowTom Berkelman, National Institutes of Health

(NIH) Research Associate4

Devaki Bhaya, NSF Research AssociatePierre Broun, Monsanto FellowRobin Bueil, United States Department of

Agriculture (USDA) FellowGregory D. Colello, National Aeronautics and

Space Association (NASA) ResearchAssociate

John P. Davies, USDA Research AssociateDeane Falcone, Department of Energy (DOE)

Research AssociatePierre Friedlingstein, Columbia University

Fellow?Wei Fu, NASA Research AssociateEva Huala, Carnegie Fellow5

David M. Kehoe, NSF Research AssociateWolfgang Lukowxtz, DGE Research Associate6

Michelle Nikoloff, NSF FellowYoko Nishizawa, NSF Research AssociateKrishna Niyogi* Life Sciences Research

Foundation FellowJoseph P. Ogas, DOE Research AssociateMarsha Pilgrim, Carnegie FellowAnne Ruimy, DOE Research Associate

Rakefet Schwarz, International HumanFrontier Science Fellow

Wayne Stochaj, NSF FellowSusan S. Thayer, NSF Research AssociateKlaas van Wijk, NSF Research AssociateIain Wilson, USDA Research AssociateJames Zhang, DOE Research Associate

Students

Sean Cutler, Stanford UniversityM. Elise Dement, Stanford UniversityPierre Friedlingstein, Columbia University7

Stewart Gillmor, Stanford UniversityClaire Granger, Stanford UniversityGeeske Joel, Stanford UniversityLianne Kurina, Stanford University8

Catharina Lindley, Stanford UniversityChris Lund, Stanford UniversityCarolyn Malmstrom, Stanford UniversityMargaret Olney, Stanford UniversityJulie Oshorn, Stanford University9

Johannna Polsenberg, Stanford University10

Jim Randerson, Stanford UniversitySteven Reiser, Michigan State UniversitySeung Rhee, Stanford UniversityWaltraud Schulze, University of Regensburg,

Germany1*Chris Still, Stanford University12

Dennis Wykoff, Stanford University

Support Staff

Ann Blanche Adams, Laboratory Assistantn

Cesar R. Bautista, HorticulturistJohn Becker, Laboratory Assistant14

Kathryn Bump, Administrative Assistant15

Catherine Cassayre, Laboratory Assistant16

Cecile Coulon, Laboratory Assistant17

Nadia Dolganov, Research AssociateGlenn A. Ford, Laboratory ManagerMarcia Green, Laboratory AssistantlH

Cyril D. Grivetf Senior LaboratoryTechnician1^

Nathaniel Hawkins, Laboratory Technician20

Doug Hughes, Laboratory Technician21

Angela Kalmer, Laboratory Assistant*2

Robert Lee, Laboratory Assistant21

Barbara March, BookkeeperLaura Me Laity, Laboratory AssistantCeara McNirT, Laboratory Assistant-4

\ i \v IK

Sandra Merzner, Laboratory Technician25

Barbara Mortimer, Laboratory TechnicianErik Nelson, Laboratory Assistant26

Frank Nicholson, Facilities ManagerMarc Nishimura, Laboratory Technician7

Devin Parry, Laboratory Technician27

Pedro F. Pulido, Maintenance TechnicianMelani Reddy, Laboratory AssistantLarry D. Reid, Maintenance TechnicianCourtney Riggle, Laboratory Assistant28

John Robison, Laboratory Assistant29

Connie K. Shih, Senior LaboratoryTechnician

Mary A. Smith, Business ManagerColby Starker, Laboratory TechnicianDonna Sy, Laboratory Assistant™Ann Tornabene, Laboratory Assistant11

Liping Wang, Laboratory Assistant12

Rudolph Warren, Maintenance TechnicianAida E. Wells, SecretaryBrian M. Welsh, Mechanical EngineerHoward Whitted, Support Engineer

'From December 11, 1995 toApril 11, 1996

-To September 16, 1995To May 15, 19964To September 30, 1995"'From May 1, 1996"From March 1, 1996:From February 1, 1996"From November 1, 1995'From October 1, 1995'^From April 22, 1996"From April 1, 1996

!ZFromJune 1, 19961'From April 18, 1996"From June 17, 19961'From October 16, 1995"Tojune 5, 1996l7From June 19, 1996t sFromMarch6, 1996 to April

19, 1996•Died July 17, 1996*TbMay3I , 199621 From November 30, 1995-From November 29, 1995 to

March 11, 1996iMFrom February 2, 1996•"From May 22, 1996^From May 13, 1996"From April 10, 1996-'From July 5, 1995-"From June 18, 1996-"From October 10, 1995vFrom May 21, 1996"To August 31, 1996"From August 21, 1995

• Yf

• Bibliography •1280 Adam, L, and S. C. Somerville, Genetic

characterization of five powdery mildewdisease resistance loci in Arahidopsis thaliana,Plant}. 9(3), 341-356, 1996.

1305 Apt, K. E, R G. Kroth-Pancic, and A. R.Grossman, Stable nuclear transformation ofthe diatom Phaeodactylum Tricornutum, Mol.Gen. Genet., in press, 1996.

1272 Apt, K. E, A. Sukenik, and A. R.Grossman, The ER chaperone BiP from thediatom Phaeodactylum (GenBank U29675),Plant Physiol 109, 339-345, 1995.

1224 Berry, J. A., P. J. Sellers, D. A. Randall, G. J.Collatz, G. D. Colello, S. Denning, and C.Grivet, SiB2, a model for simulation ofbiological processes within a climate model,in SEB Seminar Series—Scaling Up, P. vanGardingen, G. Foody, and P. Curran, eds., pp.1997, Cambridge University Press, Cambridge,in press.

1243 Briggs, W. R., E. Liscum, P. W. Oelier, and J.M. Palmer, Photomorphogenic systems, inLight as an Energy Source and InformationCarrier in Plant Physiology, R. Q Jennings, G.Zuchelli, F. Ghetti, and G. Columbetti, eds.,pp. 159-167, Plenum Publishing, New York,1995.

1284 Chiariello, N. R., and C. B. Field, Annualgrassland responses to elevated CO2 in long-term community microcosms, in CarbonDioxide, Populations and Communities, C.Kornerand E A. Bazzaz, eds., pp. 139-157,Academic Press, San Diego, 1996.

1282 Davies, J. P., F. Yildiz, and A. R. Grossman,Sacl, a putative regulator that is critical forsurvival of Chlamydomonas reinhardtii duringsulfur deprivation, EMBO Journal 15(9),2150-2159, 1996.

1236 Fredeen, A., G. W. Koch,, and C. B. Field,Effects of atmospheric CO2 enrichment onecosystem CO2 exchange in a nutrient andwater limited grassland,/, Biogeography 22,215-219, 1996.

1185 Fredeen, A. L., and C. B. Field, Constraintson the distribution of Piper species, in TropicalForest Plant Ecophysiology, A. P. Smith, K.Winter, S. Mulkey, and R. L. Chazdon, eds.,pp. 597-618, Chapman and Hall, New York,1996.

1235 Giest\ HM S- Hippe^Sanwald, S. Somerville,and J. Weller, Erysiplw gramtnis, in M\cofci, G,Carroll and P. Tudzynski, eds., Springer-Verlag,Berlin, Vol. VI, in press, 1995.

1261 Gilmore, A. M., T. L Hazlett, O. Bjorkman,and Govindjee, Xanthophyll dependent non-photochemical quenching of chlorophyll,fluorescence at low physiological temperatures,Proceedings of the Xll International Photosynthe-sis Congress, in press.

1169 Goulden, M. L, Carbon assimilation andwater-use efficiency by neighboring Mediterra-nean-climate oaks that differ in water access,Tree Physiol. 16, 417-424, 1996.

1178 Herbert, S. K., and D. C. Fork, Lightadaptation of cyclic electron transport throughphotosystem I in the cyanobacteriumSynechococcus sp. PCC 7942, Photosyn. Res.,in press.

1281 Holbrook, N. M., M. J. Burns, and C B.Field, Negative xylem pressures in plants: atest of the balancing pressure technique,Science 27Q, 1193-1194, 1995.

1285 Hungate, B. A., F. S. Chapin III, K L.Pearson, and C. P. Lund, Elevated CO2 andnutrient addition alter soil N cycling and Ntrace gas fluxes with early season wet-up inCalifornia annual grassland, Biogeochem., inpress.

1248 Jackson, R. B., Y. Luo, Z. G. Cardon, O. E.Sala, C. B. Field, and H. A. Mooney, Photo-synthesis, growth, and density for thedominant species in a CO2-enriched grassland,J. Biogeography, in press.

1303 Kehoe, D., and A. Grossman, Similarity of achromatic adaptation sensor to phytochromeand erhylene receptors, Science 273, 1409—1412, 1996.

1296 Korner, C, F. A. Bazzaz, and C. B. Field,The significance of biological variation,organism interactions and life histories in CO :

research, in Carbon Dioxide, Populations andCommunities, C. Korner and F. A. Bazzaz, eds.,pp. 443-456, Academic Press, San Diego,1996.

1287 Licsum, E., and W. R. Briggs, Mutations intransduction and response components of thephototropic signalling pathway, Plant Physiol,,in press.

1302 Malmstriim, C. M., and C. B. Field, Viral-induced differences in response of oat plants toelevated carbon dioxide, Plant Cell Environ., inpress, 19%,

H I 9 Meyer, K., J. Cusumano, C R. Somerville,C. Chappie, Ferulute 5-hydroxylase fromAwhtdopsis t/wiuTU defines a new family ofcvu chrome P450-dependent monoxygenases,

Y* \i IV«^ ^ • 115

Proc. Natl Acad. Sci. USA 93, 6896-6874,1996.

1289 Oelier, P., E. Liscum, and W. R. Briggs, Bluelight-activated signal transduction in higherplants, in Signal Transduction in Plants, P.Aducci, ed., Birkhauser Verlag, Basel,Switzerland, 1996.

1252 Palmer, J. M., K. M. F. Warpeha, and W. R.Briggs, Evidence that zeaxanthin is not thephotoreceptor for phototropism in maizecoleoptiles, Plant Physiol., in press.

1292 Quisel, J. D., D. D. Wykoff, and A. R.Grossman, Biochemical characterization of theextracellular phosphatases produced byphosphorus-deprived Chlamydomonasreinhardtii, Plant Physiol I I I , 8 3 9 - 8 4 8 , 1 9 9 6 .

1250 Randall, D. A., P. J. Sellers, J. A. Berry, D.A. Dazlich, C. Zhang, G. J. Collate, A. S.Denning, S. O. Los, C. B. Field, I. Fung, C. O.Justice, and C. J. Tucker, A revised landsurface parameterization (SiB2) for atmo-spheric GCMs. Part 3: The greening of theCSU GCM, J. Climate 9, 738-763, 1995.

1293 Randerson, J. T, M. Thompson, C.Malstrom, C. Field, and I. Fung, Substratelimitations for heterotrophs: implications formodels that estimate the seasonality atatmospheric CO2, Global Biogeochem. Cycles,in press.

1298 Ruimy, A., L Kergoat, C. B. Field, and B.Saugier, The use of CO : flux measurements inmodels of the global terrestrial carbon budget,Global Change BioL, in press.

1237 Scott-Craig, J. S., K. B. Kerby, B. D. Stein,and S. C Somerville, Expression of anextracellular peroxidase that is induced inbarley (Hordeum vulgare) by the powderymildew pathogen (Erysiphe graminis f. sp.hordei), Physiol Mol Plant Pathol 47, 407-418, 1995."

1295 Sellers, P. J., L Bounoua, G. Collate, D. A.Randall, D. A. Dazlich, S. La, J. A. Berry, I.

Fung, C. J. Tucker, C. B. Field, and T. G.Jenson, A comparison of the radiative andphysiological effects of doubled CO2 on theglobal climate, Science 271, 1402-1406, 1996.

1249 Sellers, P. J., D. A. Randall, C. J. Collate, J.A. Berry, C. B. Field, D. A. Dazlich, C. Zhang,and G. D. Colello, A revised surface param-eterization (SiB2) for atmospheric GCMs. Part1: Model formulation, J. Climate 9, 676-705,1996.

1316 Somerville, C. R., The physical map of anArabidopsis chromosome, Trends Plant Sci. 1,2,1996.

1317 Somerville, C. R., Harnessing Arabidopsis tothe Plow in Proceedings of FAO/1EAESymposium on the Use of Induced Mutations andMolecular techniques for Crop Improvement,Vienna, pp. 401-410, 1995.

1318 Somerville, C. R. and J. Browse, Dissectingdesaturation: plants prove advantageous,Trends CellBiol. 6, 148-153, 1996.

1310 Stochaj, W. R-, and A. R. Grossman, Acomparison of the protein profiles of culturedand endosymbiotic Symbiodinium bermudensefrom the anemone Aiptasia pallida, J. Phycol,in press.

1283 Stochaj, W. R., and A. R. Grossman,Dramatic differences in the protein of free-living and endosymbiotic Symbiodinium sp.from the anemone Aiptasia pallida, Proceedingsof 8th International Coral Reef Symposium, inpress.

1301 Thompson, M. V., J. T. Randerson, C. M.Malmstrom, and C. B. Field, Change in netprimary production and heterotrophicrespiration: what is necessary to sustain theterrestrial sink?, Global Biogeochem. Cycles, inpress.

1307 Yildiz, E, J. P. Davies, and A. R. Grossman,Controlled expression of the ATP sulfurylasegene of Chlamydomonas reinhardtii, PlantPhysiol, in press.

fit* \?< f I v r i • Yi ft 95

z

H

3i•

First row, left to right: G. Cod/, M. Fogel. D. Mao. B. Hazen. D. Rumble. Y. Fei, N. Irvine. H. Yoder. C. Prewitt.). Bqyd. F. Press. B. Mysen. R. Hemle/. R. Cohen, L. Finger.).Frantz. and D. Virgo. Second row. left to right: G. Zou. D. Frost. R. Zhang, |. Shu. M. Wah, L. Patrick. P. Roa. P. Meeder. D. George. S. Schmidt, G. Goodfriend, J. Kokis. S.Hardy, C. Wolfe. G. Shen. |. Blank, and M. Imlay. Third row. left to right: B. Brown, C. Hadidiacos. W. Lei. R. Lu. M. Wolf. T. Hammouda. C. Lynch. D. Teter. M. Teece. J.Farquhar, J, Ita, S. Zha. |. Linlon, P. Conrad, B. Struzhkin, A. Goncharov, !. Mazin, B. Johnson, and E. Hare. Fourth row. left to right: V. Kress, H. Yang. T. Schindelbcck. R.Gierc. B. Downs. C. Bertka. J. Straub. S. Merkel. G. Saghi-Szabo, B. Kiefer, P. Lazor, L. Stixrude. D. Von Endt. T. Oudemans. G. Zha, L. McGill. C. McCaulay. and D. Bell.

Director's Introduction

International visitors to the Geophysical Laboratory are often surprised at thesmall size of its staff, given the Lab's enormous influence on the earth andmaterials sciences. Much of the Lab's reputation is based on broad studies of

physical and chemical studies of inorganic rock-forming minerals, i.e., oxides,silicates, and sulfides, and the roles these minerals play in igneous and metamor-phic processes. The accompanying three articles illustrate other dimensions inearth science research at the Lab, all extending substantially beyond what manyconsider to be its central research theme. In the first article, Marilyn Fogel andBeverly Johnson describe their investigations of • _ « „ ^ _ • « _ _ « _ • • « • _ .the carbon and nitrogen isotope variation in u There IS everymodem and ancient emu eggshells collected • j.from the Great Australian Desert. Their studyseeks to answer whether the Australian conti- that...research in thenent was once more heavily forested than it is interface betweentoday, and whether the ancient aboriginal organic and inorganicpeople were responsible for the deforestation geochemistry willthrough their large-scale burning practice— .• n • i, , r t

s ,, . . . continue to flourishglobal change caused by anthropogenic inter-vention! and expand

The other two articles describe research thathas benefited enormously by the availability of new technology. In one, GeorgeCody describes how a unique x-ray microscope at the National Synchrotron LightSource enables him to obtain detailed images of a variety of ancient organicmaterials, ranging from fossil kerogen to coal. These images provide organicstructural information unavailable by any other method, and will undoubtedlyhelp in understanding how coal and petroleum deposits are formed.

In the third article, Douglas Rumble describes an exciting new discovery inrocks from China showing that the rocks were subducted deep into Earth's uppermantle and then transported back to the surface with little alteration of theirisotopic signatures. In this work, he uses a new laser fluorination technique hedeveloped that allows him to analyze oxygen isotopes on very small areas (~10firn)of the minerals of interest. This provides detailed mapping of the isotopic variationacross and between the mineral grains. The results suggest that the climate was

Yl W W H 'k ^5 • L*\%\ti 11

very cold in the area where the originalrocks were formed more than 200million years ago.

Together, these essays show thebroad but also closely-linked research ofthree collaborating staff members,covering global change on differentspatial and time scales, using different

techniques, and combining field workin widely separated areas of the world.There is every indication that theGeophysical Laboratory's research inthe interface between organic andinorganic geochemistry will continue toflourish and expand in the future.

—Charles T. Prewitt

Beverly Johnson and Marilyn Fogel began their journey through the Australian Outback in the desolate LakeEyre Basin, above. (See map on p. 123.) Photo by Chris Swarth.

• Yl

Isotopic Tracers of Climatic Changein the Australian Outback

by Marilyn L. Vogel and Beverly ]. Johnson

The geological record shows that major changes in the climate of theAustralian Outback have occurred over the past 150,000 years. Most ofthese climate shifts are related to Milankovitch sunspot cycles, which

affect the intensity of the Asian monsoon and thus impact the area's rainfall.Milankovitch cycles, however, can not explain the most recent shift, from wet todry climate, that has occurred in the Australian interior over the last 20,000 years.We hypothesize that humans, throughtheir practice of frequent, large-scalelandscape burning, may have beenresponsible for the changes in vegeta-tion that forced this climate shift.

Humans came to the Australiancontinent about 60,000 years ago.These hunter-gatherers used fire tohunt, promote the growth of certainplants, send signals, and in religiousceremonies. Over the long term, —---«»---•——------«-—-----—--«------—

frequent burning alters the landscapedramatically; only plants able to tolerate burning more often than every 20 yearssurvive in large numbers. In addition, burning alters soil fertility, producing soilswith very low nitrogen, phosphorus, and organic matter contents. As a result,plants and soils sequester less moisture, and monsoon rainfall entering Australiafrom the north can't easily transfer moisture into the continent's interior.

Researchers are learning whythe Australian Outback

became the desert it is todaythrough an unlikely source—the emu, a large, flightlessbird native to the "down

under'* continent.

Marilyn Fogel lias been exploring the inter faces. fjet^biology .mod the -earth sciences since |aiiiIag:Cariic|iie%,.'

biology fri»t PciwiSflvtiiiiii. .S^e-lliiiv«*^ty/siiid.it:?li*I)*:.In bcifSfiT fiiiarifte :§€:§eiice} frwii'-ilb^IJ^

r . '••

Establishing the ClimateConnection

The first step in our effort to under-stand how humans may have influ-enced the Australian Outback was toestablish a means to assess the climatechanges that have occurred over thelast 50,000 years. Towards this end, we(with our U.S. and Australian collabo-rators) have been studying thegeochemistry and geology of the LakeEyre Basin. Our tools include the stable(i.e., nondecaying) isotopes of carbonand nitrogen in modern and fossil emushells. Previous work by BeverlyJohnson demonstrated that the isotopicsignals of the eggshell of a related bird,the ostrich, are stable over geologicaltime and that they record informationon the animal's diet. Because thisinformation can be linked to patterns ofrainfall, temperature, and vegetationwhen the animal was still alive, thefossil ostrich eggshells can be used asclimate indicators. We are applying thesame principles to emu eggshell.

The basic hypotheses of our studyare the following: (1) The carbon andnitrogen isotopic compositions of plantsreflect the climate and the environ-ment in which they grow. (2) Animalsfeeding on these plants incorporate theplant's isotopic tracers into their owntissues and into those of their predators,passing the signatures up the food

Marilyn Fogel gathering plant samples.

chain. (3) Fossilized remains of animals,such as bones and shells, retain theseisotopic signatures, and thus provide arecord of changes in ancient climatesand environments.

During July and August of 1994, wecollected samples of modern vegeta-tion, soils, and emu eggshell along a3,500-km transect across the interior ofAustralia. (See map, next page.) (Ourtrack was very similar to that of a 1930sDTM magnetic expedition.) To verifythe links between diet, vegetation, andclimate, we collected samples over arange of climatic conditions, from the

From 1991 until 1993, Beverly Johnson was a predoctora!

fellow at the Geophysical Laboratory, where she did

research leading to a Ph.D. She received her degree' in

1995 from the University of Colorado and since then has

been working with. Marilyn Foget as a, postdoctoral fellow.

• Yfc.\K

Top End

Cooktown

Cairns

Townsville

Brisbane

mm rainfall

>1200650-1200 Summer350-600

Pn 500-800 WinterH 250-500

(HI >800

Ifll 500-800 Uniform

rn 250-500

[ | <250-350 Arid

| | Alpine

- - - Marilyn Fogel- • • Beverly Johnson

very dry Lake Eyre Basin (1.50 mmrainfall per year) to tropical locations atthe Top End outside of Kakadu Na-tional Park (1,100 mm rainfall peryear).

Sampling the vegetation of such avast and diverse continent as Australiawas a daunting proposition. Ourstrategy was to collect representative

Melbourne

species of the principal components ofthe vegetation—and the soils associ-ated with them—seven differentlocations along the transect. Thisincluded species with known firesensitivity or tolerance. Some species,for example Macropteranthes keckvueckii

(also known as bulwoody), dominatedthe north-central regions of Australia10,000 years ago. Today, bulwoodyoccurs only in small patches with a verynarrow range near the town of DalyWaters. This plant and others like it areunable to withstand fires more fre-quently than about every 50 years.Other plants, such as the pricklyspinifex grasses, Triodia spM require fireto give them a competitive edge.Almost all of the north-central area ofAustralia is now covered with spinifexgrasses.

To understand haw emu diet islinked to climate, we also gatheredremains of emus and the plants and

Y? M B • 123

Spinifcx grass, a common inhabitant of north-central

Australia.

insects they commonly eat. (Wecollected one unfortunate emu from aroadside accident.) Emus mostly eatseeds, small shoots of grasses and herbs,flowers, and fruits, but they have beenobserved eating insects, includinggrasshoppers, caterpillars, and otherlarvae. The insects we collected camefrom one location in the middle of theGibber Plains region, where we ob-served a flock of emus eating grasshop-pers.

Measuring Isotopes inPlants and Soils

Since our 1994 expedition, we havemeasured the carbon (8HC) andnitrogen (815N) isotope ratios of over200 species of plants. The ratios of BCto 12C, and I5N to I4N, both expressedin parts per thousand (%o), show up inevery tissue of every plant.1

Depending on how plants initiallyprocess their incoming carbon dioxide,they arc categorized as either C, or C4.Most tropical grasses and other plantsadapted to hot, dry climates are C4

plants. Shrubs and trees tend to use theCp pathway. We found that the C;|

plants we collected varied in theircarbon isotope ratios from -25%o atLake Eyre to almost -30%o at the TopEnd. This variation accurately reflectedthe region's mean annual precipitation,which affects the water-use efficiency ofthe plants. (The more water availableto the plants, the more open are thestomates—the tiny pores on the plant'ssurface. This allows more CO2 to diffusein and out, ultimately affecting theratio of the carbon isotopes.) Thegrasses and other C4 plants we collectedhad isotopic ratios that were essentiallythe same over the precipitation spec-trum (S13C = -13 ± 2%o). However,average SnC values from the sevensampling stations, including both C3

and C4 plants, clearly revealed theeffect of climate on the overall vegeta-tion. (In drier regions, C4 grassesconstituted a greater proportion of thevegetation and so the effect of precipi-tation on 8I3C of all plants was slightlygreater.)

The 815N we measured in the plantswras, like the SnC, strongly correlatedto mean annual precipitation, thoughthe presence of Acacia shrubs, which fixatmospheric nitrogen gas via bacteria intheir roots, slightly dampened thetrend. The median centered around+5%o, with a range of from -3 to +15%o.Nitrogen-fixing shrubs had an averagevalue of about +l%o. Plants incorporatenitrogen typically from a pool ofoxidized or reduced forms of nitrogen intheir soils. To learn how the plant andsoil reservoirs were related in oursamples, we measured the isotopiccompositions and concentrations of

t ah v t tt - m tint tin tiitir 'nR»4n!\ up the ttH>d chain, so that an animal contains practically the same carbon* T* I' ' -*1 - l" T^t [-1 HIT it citv Njlr*»jen, though, becomes slightly enriched in iVN as one proceeds up the chain.

124 • V ft -

ammonium and nitrate in many of thesoils we collected. All our soil samplescontained only a fraction of the solublenitrogen (and phosphorus) found in therich soils of the United States. Butwhile there was greater variation of the8I5N in the plants than there was in thesoils, the relationship between precipi-tation and soil nitrogen isotopiccomposition was strong. The plants hadthus incorporated the nitrogen isotopesalmost directly from the soil.

While we found a strong plant-soilconnection for nitrogen, the carbonisotopic composition of the soils hadvery little relationship to the carbonisotopes of the plants. Soil collecteddirectly under a C4 spinifex grass (S13C= -13), for example, had an isotopiccomposition enriched in 12C to -18%o,but it still varied by 5-6%o from theSnC of the grass itself. Organic matterin soils generally contains plant frag-ments mixed with a pool of biologicallyunreactive carbon that can be severalthousands of years old. Indeed, organicmatter in paleosoiis has the potentialfor retaining its isotopic signature overgeological time. It can thereforecontain a record of the SBC of ancientvegetation. But our results indicate thatthese modern soils, like most of the

soils in Australia, have either beenburned or are heavily weathered. Eitherway, they contain very little organicmatter.

Analyzing the Eggshells

Once we finished analyzing our plantand soil samples, we were ready tomeasure the isotopes in emu eggshell.The modern emu eggshell we collectedcame from a slightly different transectthan the one yielding soils and vegeta-tion, but it extended through similarclimatic regimes. The task of searchingfor emu eggshells is similar to the job ofa fireman—a lot of tedious boredompunctuated by moments of excitement.Beverly Johnson was able to gathereggshells from as far south as KangarooIsland and as far north as the Gulf ofCarpenteria. She obtained specimensfrom station holders, who found themon their ranches, and from museumcollections. She also discovered severalnests with broken or whole eggshells indesolate parts of the Great SimpsonDesert.

Organic matter in eggshell consistsprimarily of proteins with some at-tached carbohydrates. The stableisotopic composition of this organic

matter is directly related to the diet ofthe emu just before she lays her eggs. Inessence, it records the emu's previousfew weeks of meals. The stable nitrogenisotopic ratios we measured in the shellsindicate that the shells' organic matterdoes reflect mean annual precipitation,that is, the isotopic signal was passedfrom soil to plant to emu. However, acomplication arose. In the very aridregions surrounding Lake Eyre, the 8l5Nof the emu was greater than one wouldhave predicted basedon prior animalmeasurements. Ordi-narily, the 815N of ananimal is 2-5%o morepositive than that of itsdiet. In controlledfeeding situations withcaptive birds, thedifference in S15Nbetween diet andeggshell is typically3%o. Eggshell fromLake Eyre, however,was enriched by at least %

6%o relative to coexist- £ing vegetation. It is u

known that emus cansurvive on a diet withvery low nitrogen content, as they areable to retain and recycle nitrogenrather than excrete it. The increasedisotopic fractionation we observedcould thus result from greater nitrogenretention. Alternatively, it could becaused by omnivorous feeding practices,i.e., by the presence of insects in theemu diet.

The grasshoppers we collected hadextraordinarily enriched Sr"N values( + 15°bo) relative to that of emu feather(8^N = +12). The plants eaten by the

An emu roams the desolate landscape.

emus, in contrast, had an average 815Nof approximately +7%o. Mass balancecalculations indicate that about 25% ofthe emu's nitrogen could thus beoriginating from insects. Because plantsgenerally have very little nitrogenrelative to protein-rich insects, compli-cations of omnivory must therefore beaddressed when assessing fossil eggshellfragments.

Most of the fossil eggshell sampleswe analyzed were collected by Gifford

Miller of the Univer-sity of Colorado.Miller is a formerpredoctoral andpostdoctoral fellowwith GeophysicalLaboratory staffmember Ed Hare. (Hewas also Johnson'sdissertation advisor,)He has been gather-ing small, one-cmfragments of ratiteeggshell from thescorched shores ofLake Eyre since 1990.In areas where thestratigraphy of thesediments has been

preserved, he can place the eggshellaccurately in geological context. Wherewind has deflated the sediments, he canalso find eggshell fragments on theground. Fogel spent several days (andJohnson several weeks) with Millerduring the 1994 field expeditionwalking slowly around the shoreline ofLake Eyre looking for glimpses of shellfragments. Miller has a trained eye, andcan easily tell the difference betweenemu eggshell and that of Genyomis, aneven larger ratite that went extinct

126 C\u\\. u K-rm

about 30,000 years ago. The fossileggshells are rich with geochemicalinformation. The shell's carbonate canbe radiocarbon dated; amino acids inthe organic residues can be tested foralloisoleucine-to-isoleucine ratios,which give relative ages; and theisotopic compositions of the carbonateand organic fraction record dietary andclimatic information. All of theseanalyses can be performed on a one-cm-square bit of shell.

As part of her dissertation, BeverlyJohnson developed the protocol foranalyzing the isotopic compositions inmodern and fossil ostrich eggshells.(She performed this work as a predoc-toral fellow at the Laboratory from1991-1994.) She used the sametechniques to analyze some 450 radio-carbon-dated emu eggshells from theLake Eyre basin, encompassing a rangein age from 0 to 150,000 years.

Her data clearly reveals changes inisotopic composition as a function oftime. Both the nitrogen and the carbonisotope records indicate that the emudiet changed sometime around 10,000years ago. The animals began to eatplants with isotopes mirroring a morearid environment. Interpretationsbeyond this must be made very care-fully. We are well aware of the compli-cations in tracing backwards thecomplex environmental, vegetational,and dietary isotope signatures of fossilsamples, especially considering thevariability in the diet of modem emu.To convince us that isotopic trends are,indeed, indicative of long-term climaticchange, we realize that we must analyzemany more fossil samples.

The remaining challenge is twofold.Miller and his Australian colleagues areactively seeking a fossil locality with acontinuous sedimentary record in aregion north of Lake Eyre. The additionof a second site would allow us tocompare dates and isotopic swings, andverify that we are recording continentaland not regional climate. Meanwhile,Johnson will be starting an NSFInternational Fellowship at the Univer-sity of Woolangong in late 1996. Shewill be searching for vegetationaltracers in the 513C of isolated lipidsfrom terrestrial plants preserved insediments in the Gulf of Carpenteria.She hopes the marine sediments holdterrestrial climate signals.

Our second challenge involves thelink of climate to human activity,especially to the practice of burning.Archaeological remains in the area aresparse and difficult to obtain. Charcoalfragments and organic products fromburning, such as polycyclic aromatichydrocarbons (PAHs), may hold furtherclues.

Because our task is not yet finished,our conclusions are tentative. We areconfident that the isotopic composi-tions of plants and soils in centralAustralia change as a function of meanannual precipitation, and that theorganic matter of modern emu eggshellmirror these isotopic signals. Butbecause of complications arising fromthe animal's diet and physiology, weonly cautiously interpret that fossil emueggshells are an accurate barometer of

the changes in vegetation and meanannual precipitation over the last 10-15*000 vears.

.-» K - M >

Ancient Structures:Probing the Chemistry of Organic

Matter Diagenesisby George D. Cody

Organic geochemists like myself are interested in understanding whathappens over time to organic matter trapped within sedimentary rocks.When subjected to high temperatures and pressures over long periods of

time, this material, called kerogen, undergoes a process of alteration we calldiagenesis. In some cases, the reactions which occur during diagenesis lead to theformation of oil, gases, and tars. Kerogen's fate is coupled directly to the tectonicand geochemical evolution of the sedimentary basins that contain it. The cumula-tive, regional-scale changes in - I 1 1 I _ 1 — > . . . . . . . . p . ^ , . « ^ B B -

temperature, pressure, and pore-fluid chemical history of thesebasins are mirrored in kerogen'scomplex, macromolecular structure.Our challenge is to extract thisinformation using the tools oforganic geochemistry.

It seems a simple task. Given

sufficient information on the mmmmm_mmim_m_mmmmmm_m_mm_ma^^chemical structure of kerogen, oneshould be able to establish fairly easily the temperature and chemical history of thesurrounding rock (provided that one can determine the reactions operating on theorganic system). The problem is that the chemical structure of kerogen is verydifficult to characterize. To he sure, significant technical strides in analyticalinstrumentation over the past couple of decades have greatly improved our

Is carbohydrate lost to theenvironment during diagenesis

of organic matter, or is ittransformed into something

else? The answer may impactour understanding of theEarth's carbon budget.

.George, D* Cody is the newest staff member at theGeophysical Laboratory* He came to Carnegie in 1.995.,following a postdoctoral fellowship at Argonne National

I^bos#t<jcy. He received Iris Ph.D. in 1992 at Pennsyl-

%stM Slate Ofilvcrsitf f where tie first became interestedia keffTOtti's macrcwicileetilar stnicttice*

• \-v

understanding. Pyrolytic-gas chromato-graphic techniques, for example, whencoupled with mass spectrometry, enableus to obtain information about thediscrete molecular "building blocks" ofthe bio/geopolymer. And nC solid-statenuclear magnetic resonance (NMR)spectroscopy can give us detailedinformation on kerogen's specificorganic functional groups. Bothtechniques thus reveal considerabledetail about kerogen. However, neithertechnique yields representative infor-mation on all of kerogen's carbonaceousmaterial. As well, both techniquesaverage all spatial chemical heterogene-ity which exists within kerogen at thesub-microscopic scale. Such limitationsclearly compromise our capabilities toidentify specific reaction pathways thatmodify kerogen during diagenesis.

Applying Synchrotron-BasedInstrumentation

The microheterogeneity of kerogenhas long been a challenge to organicgeochemists. Recent technology,however, has begun to meet thatchallenge. For example, a uniquescanning soft x-ray microscope(STXM) and spectrometer now enablesgeochemists to explore the detailedorganic structure of kerogen, and otherorganics, in the sub-micron range.Located at the National SynchrotronLight Source at the BrookhavenNational Laboratory, this instrument iscapable of resolving physical structuredown to 50 nanometer spatial resolu-tion, with an energy (or frequency)resolution of 03 eV. (A nanometer is abillionth of a meter) It operates Kith asa microscope, recording images with

the photon energy fixed to a selectedvalue, and as a microspectrophotom-eter. As such, it is able to differentiatestructure within discrete regions ofheterogeneous material by detectingtheir characteristic x-ray absorptionspectra. The instrument is a majorachievement in microanalyticalscience, and reflects the vision andcapabilities of its creator, Janos Kirz,and his colleagues at SUNY StonyBrook's Department of Physics.

Near-Edge Absorption FineStructure Spectroscopy

Over the past several years, I havebeen involved in applying the STXMto a number of fundamental problemsin organic geochemistry, probing spatialand chemical variations of such ele-ments as carbon, oxygen, calcium,potassium, and chlorine. The spectros-copy I employ is commonly referred toas Near Edge X-ray Absorption FineStructure Spectroscopy (NEXAFS).

The physics of NEXAFS is straight-forward. The absorption of a photon oflight in the soft x-ray region promotescore-level electrons to higher-energy,unoccupied electronic states. A photonis absorbed when its energy equals theenergy difference between an electronin its electronic ground state and thatelectron in an excited state. Themagnitude of this energy "gap" changeswith differences in nearest-neighborelectronic interactions, i.e., chemicalbonding. Thus, a NEXAFS spectrumprovides information on the distribu-tion ot different chemical bonds withina sample. In general, the intensify oiabsorption scales linearly with theconcentration oi a yiven atomic species

in a given electronic environment;however, there is a proportionalityconstant intrinsic to each transition,and this constant can vary substantiallyfrom one electronic environment toanother- It is thus a great challenge toobtain truly quantitative data. Onemust determine independently themagnitude of the proportionalityconstant so that the intrinsic oscillatorstrength of a given core-level electronictransition can be ascertained. I typicallyuse synthetic or well-characterizednatural standards, as well as otherspectroscopic methods (e.g., nuclearmagnetic resonance spectroscopy), todetermine the oscillator strengths ofgiven transitions. Once I've obtainedthese, I am able to quantify theNEXAFS spectra in terms of theabundances of different bondingenvironments, for example carbon inkerogen's various organic functionalgroups.

Tracing the Fate ofPolysaccharides in Ancient Wood

Kerogen is generally thought to bethe product of selective preservation ofresistant, chemically stablebiomacromolecules that survive earlydiagenesis. By far the most abundantbiomacromolecular component inplants are the carbohydrates, princepally cellulose. (Carbohydrates aremolecules constructed from carbon,hydrogen, and oxygen; cellulose, apolymer of glucose, provides the mainstructural support of plant cell walls,and is probably the most commoncarbohydrate on Earth.) Recently, Ihave been exploring the fate of carbo-hydrates in wood and woody tissue-

derived organics which have undergonechemical structural evolution duringvarious stages of diagenesis.

Numerous studies on recent andancient organic-rich sediments havesuggested that carbohydrates disappearfrom the organic assemblage earlyduring diagenesis. For example, instudies where pyrolysis-gas chromatog-raphy-mass spectrometry is employed,one observes a progressive reduction inthe concentration of polysaccharide-derived pentose and hexose sugars fromsamples corresponding to positionsalong the diagenetic pathway ofincreasing temperature, pressure, andtime. Using 13C solid-state NMR, oneobserves a reduction in absorptionintensity at ~75 and 100 ppm, corre-sponding to the secondary alcohol andanomeric carbon present in polysaccha-rides. (ppm refers to a shift in resonantfrequency relative to a standard fre-quency.) The lost carbohydratessupposedly are recycled back into theenvironment, presumably as carbondioxide and water. This inter-pretation—that the carbon associatedwith carbohydrate is lost duringdiagenesis—underlies the principalassumption regarding the mass balancebetween sedimentary organic carbonwhich is recycled and that which isretained in the sedimentary record.

To gain a better understanding of thefate of carbohydrates during diagenesis,I have been studying the kerogenderived from ancient wood, using theSTXM technology at Brookhaven.Here I highlight two particularlyinteresting and illuminating examples.The first is an Eocene metasequoiawood some 40 million years old from aCanadian Arctic fossil forest on

iill \\<JIV,

Ellesmere Island, north of the ArcticCircle. The second is a considerablyolder, Cretaceous sample of wood (some90 million years old) from coal-bearingstrata in the western United States.

To determine the overall chemistryof each sample, and to obtain quantita-tive organic functional group informa-tion, I used 13C solid-state NMR. Figure1 (top) presents the NMR spectrum ofthe Eocene wood. The relativelycomplex resonance structure revealscarbon distributed in a variety ofelectronic environments, consistentwith the presence of polysaccharidesand lignin. Lignin is the principalchemically resistant biopolymer inwoody tissue, and so one would expectprogressively older samples to beincreasingly lignin-enriched. Theresonances at 150, 135, 120, and 50ppm correspond to the carbon in lignin,while resonances at 105 and 75 ppmreveal the carbon in carbohydrate.Approximately 50% of the carbon isassociated with carbohydrate, and 50%with lignin. In contrast, 70% of thecarbon in fresh wood is in the form ofcarbohydrates. Thus, the Eocene woodhas been diagenetically altered alongthe path leading to a loss in carbohy-drate.

The chemical structure of theCretaceous wood is considerably morediagenetically evolved than that of theEocene wood. As evident in its NMRspectrum (Fig. 1, bottom), the Creta-ceous sample lacks absorption intensityin the regions corresponding to carbo-hydrate. Even the resistant lignin hasbeen significantly modified (as seen bylosses in resonance intensity at 150 and50 ppm). The reasonable conclusionfrom these data is that the carbohydrate

250 200 -50

ppm

250 200

ppm

Figure I. I3C NMR solid-state spectra of Eocene wood(top) and Cretaceous wood (below). Resonances at150, S35, 120. and 50 ppm correspond to the carbonin lignin; resonances at 105 and 75 ppm reveal thecarbon in carbohydrate.

is lost from the system, leading to aselective enrichment of lignin along thediagenetic pathway. This would requirethat 70-90% of the carbon initiallypresent in the wood be recycled backinto the environment.

A different picture emerges whenanalyzing these same samples with theSTXM, focusing on core-level elec-tronic transitions associated withcarbon. The high-resolution image inFigure 2 reveals the microstructure ofthe Eocene wood. The image acquired,at 285 eV, reveals a spectacular tapestryof collapsed cell structure. Althoughonly cell-wall material is preserved, thecell wall is. clearly chemically differenti-ated, just as it h in living tissue* Thestriking contrasts are based on varia-tions in the absorption features ofcarbohydrate and lignin. The darkareas, i.e., regions with strong ahsorp-

y, l •

Primary cell wallMiddle lamellae

Figure 2. The cell-wall structure of

Eocene wood is revealed in the

alternating bands of light and dark

snaking across this STXM image,

taken at 285 eV. Parts are labeled in

the cartoon figure at left.

tion, are rich in lignin.(More precisely, they arerich in aromatic carbon,

and only lignin contains aromaticcarbon.) The light areas of the image,in contrast, are rich in carbohydrate.

At the center of each cell wall liesthe thin middle lamellae (approxi-mately 50 nm thick). The middlelamellae exhibits intense absorptionconsistent with a lignin-rich composi-tion. On either side of the middlelamellae lies the primary cell wall, richin carbohydrate (as evident by the lowabsorption). Beyond this lies thesecondary cell wall, which includes tworegions—SI and S2. The SI region,immediately adjacent to the primarycell wall, is depleted in lignin. The S2region, however, is clearly lignin rich.

To show that the contrast in Figure 2is not biased by simple variations incarbon density, I acquired a secondimage, with the monochromator tunedto 289.5 eV (Fig. 3). This energycorresponds to an absorption banddiagnostic of carbon in carbohydrates.

Figure 3. The same STXM image as Fig. 2. but taken

with the monochromater tuned to an energy band

(289.5 eV) associated with carbohydrate. The dark

and light areas are thus reversed. See text.

(The secondary alcohol carbon incarbohydrates has a strong absorptionband at 289.5 eV.) The image clearlyshows that carbohydrate is concen-trated in the primary cell wall. Thebasis of contrast is, therefore, due totrue variations in the distribution oflignin and cellulose within the differentregions of the cell wall, and not merelyto variations in carbon density.

Analysis of the discrete ONEXAFSspectra (Fig. 4) obtained from thedifferent regions of the cell wall revealsthe full variation in carbon chemistrywithin each region. It is noteworthythat each region exhibits absorptionintensity associated both with lignin(actually, with aromatic carbon, E =285 eV), and with carbohydrate (thatis, with carbohydrate's secondaryalcohol carbons, E = 289.5 eV, which isa hydroxylated aliphatic carbon.) Thisdoubly confirms that the contrastobserved in Figure 2 is due to localvariations in the abundance of carbohy-drate and lignin.

A second subtle, but important,point must be highlighted regarding theabsorption bands at 287.2 eV in Figure

B2 IH : i . • Yi

4. The Eocene wood is related to aconifer, a gymnosperm (as opposed toflowering plants, the angiosperms).Hence its lignin is formed exclusivelyfrom conferyl alcohol, an aromaticmolecule with two hydroxyls (OH) perring. The peaks at 287-2 eV in each ofthe spectra of Figure 4 indicates thepresence of aromatic carbon bonded toa hydroxyl (OH). One would expectthe ratio of the intensities at 285 and287.2 eV to remain constant. However,this is not the case. It is clear that thedegree of hydroxylation of the aromaticcarbon in the primary cell wall isgreater than that of the middle lamellaeor S2 region, even though the overallaromatic content is less. Assuming thatall aromatic carbon is derived fromlignin, it would, appear, therefore, thatthe lignin chemistry varies across thecell wall. This conclusion is counter towhat we know regarding the chemistryof lignin.

Before considering the potentialimplications of these results, let us turnto the older sample, the Cretaceouswood. The BC NMR of this samplereveals no carbon associated with thecarbohydrate. Yet an STXM image withthe monochromator tuned to 285 eV(Fig. 5) clearly reveals cell-wall struc-ture. Although there is less contrast(and hence less differentiation) in theCretaceous wood than there is in theEocene wood, the Cretaceous wood stillevidences the primary cell wall, as wellas the SI and S2 regions of the second-ary cell wall Clearly the primary cellwall contains less aromatic carbon thanthe secondary cell wall, even thoughthe difference in concentration be-tween the two regions is considerablyless than it is in the Eocene WCHK!

0.4 -

280 300

Figure 4. C-NEXAFS spectra of discrete regionswithin the Eocene wood's cell walls: middle lamellae,primary cell wall, SI region, and S2 region. See textfor explanation.

C - N E X A F S spectra of individualregions wi th in the Cretaceous sample(Fig. 6) reveal t ha t the chemistry of thewood -derived kerogen differs consider-ably from tha t of the Eocene w i n d . In

Yi >; H

Figure 5. STXM image of the Cretaceous wood at285 eV. The primary cell wall is still visible.

addition to the aromatic and hydroxy-lated aromatic carbon resonances at285 and 287.2 eY there is now rela-tively strong absorption intensity at286.3 eV. This is an indicator of thepresence of aldehydes or ketones, whichare additional oxidized forms of carbon.Indeed, an image obtained with themonochromator tuned to 286.3 eV(Fig. 7) yields a contrast reversal,revealing that the primary cell wall isenriched in the aldehyde or ketonefunctional group.

What the STXM clearly reveals (and1 C NMR and pyrolysis gas chromato-graphic—mass spectrometry techniquesare incapable of revealing) is thatalthough the Cretaceous sample isconsiderably more chemically evolvedthan the Eocene sample, it still retainsa degree of chemical differentiation.STXM also reveals that the diageneticevolution oi these samples involvesconsiderably more than losses ofcarbohydrate and selective preservationot Isgnin. The results suggest, in fact,

that a diagenetic pathway other thanwhat has been traditionally proposedmay be operating in these samples.Instead of carbohydrate being lostduring diagenesis, it is highly probablethat it is being transformed intohydroxylated aromatic compounds andother oxygenated carbon compounds,like ketones.

Carbohydrates have been shown toundergo reactions which form hy-droxylated aromatic carbon as well asother oxidized forms of carbon (such asketones) under relatively mild condi-tions. It is not, therefore, unreasonableto assume that similar chemistryoperates during diagenesis. If, as Isuspect, carbohydrates evolve into

hydroxylated aromatic products duringthe diagenesis of plant-derived organicmatter, it would explain the increased

Figure 6. C-NEXAFS spectra of discrete regionswithin the Cretaceous wood's cell walls: primary cellwall (top) and secondary cell wall (below). See text.

0.4

280

Figure 7. STXM image at 286.3 eV. The dark areascorresponding to the primary wail indicate ketone oraldehyde enrichment.

amount of hydroxylated carbon foundin the primary cell-wall regions of theEocene wood. It would also be consis-tent with the presence of aldehyde andketone functional groups we saw in theCretaceous wood's primary cell wall.

Currently, I am in the process ofdeveloping methods to look for specificmolecular compounds traceable to suchreactions. If the carbohydrate carbon isin fact retained in kerogen, albeit in amolecularly transformed incarnation,some major assumptions constrainingthe organic carbon budget within thegeosphere will have to be reexamined.Furthermore, the presence of substan-tial quantities of carbohydrate-derivedaromatic compounds will necessitate aserious revaluation ot our understand-ing ot the Jiagenetic evolution otlignin, which has been based on theassumption that all of the carbon inmature samples is derived from lignin.

Other Problems and Future Work

The example described here,showing how STXM can be applied toa fundamental problem in organicgeochemistry, is a very small part of amuch larger effort. I am also using thetechnique to study the physical chemis-try controlling the transformation oforganic matter into graphite duringmetamorphism, as well as the chemistrycontrolling the transformation oforganic molecules into diamondsthrough industrial processes. And, I amusing the STXM to analyze the diage-netic co-evolution of kerogens derivedfrom different biomacromolecularprecursors. This latter effort will helpme obtain time-temperature pathwaysduring sedimentary basin evolution.

In this essay, I have emphasizedspectroscopy and imaging of carbonchemistry. The STXM also enables meto explore the chemistry of chlorine,calcium, potassium, and oxygen at thesubmicroscopic level Changes in themicroscope configuration will soonallow for the analysis of nitrogen. Thishas exciting implications, for it willenable me to follow the fate of proteinsand nucleic acids during early diagen-esis.

Clearly, there is no one analyticaltool that can address all questions in afield as complex as organic geochemis-try. Nevertheless, the scanning trans-mission x-ray microscope is providingunique and, in some cases, crucialinformation that is allowing us tounravel the convoluted reactionpathways that characterize diagenesis.

puge Ok»u$ Rumble at the Geophy\kdl Laboratory's ultraviolet laser isotope miuoprohe

UHP Metamorphismand the Qinglongshan Oxygen

Isotope Anomalyby Douglas Rumble, III

In June 1994, visiting investigator TzervFu Yui (Academia Sinica, Taiwan) andI made an astonishing discovery at the Geophysical Laboratory. We measuredseverely depleted oxygen isotope ratios in eclogites from Qinglongshan,

China, indicating unambiguously the presence of rainwater This was surprisingbecause the rocks had been metamorphosedat a depth of 80 kilometers, where thepressure was at least 25,000 times that at sealevel. How, we wondered, could evidence ofrainwater survive the rigors of subduction,heating, compression, and faulting, followedby uplift back to the surface—a verticalround trip down and back of 160 km?

Subsequent research has demonstrated aremarkable sequence of events responsiblefor the Qinglongshan anomaly. Eruption ofbasaltic lavas at Earth's surface was followedby alteration of oxygen isotopes in the lavas by heated rainwater in a geothermalsystem. (This environment was probably replete with hot springs and geysers,similar to present-day Iceland.) The altered volcanics were buried and latersubjected to subduction and ultra-high-pressure metamorphism during platetectonic collisions between the ancient Sino-Korean and Yangtze continents.Finally, uplift and erosion returned the lavas to the surface in the form of themetamorphic rock eclogite. The entire process took more than 200 million years.

Most metamorphic rocks form in the mid-to-lower crust at depths of 10-30 km.Our eclogite samples, however, reached a depth of 80 km before exhumation

The presence ofrainwater in

metamorphosed rocksfrom China presents

intriguing clues aboutevents that

occurred millions ofyears ago.

Hew Kicks fxmx$£<&t& wader pressure is a leog-siandiiig. •: •.interest of IJottg Rtimble, wfao has- feeea a stiff memberat titc Geopfcfsicrf Liiboralcsrf sinise 1973* RiiiuMe isals# Interested in the geoc|tfttiilst:irf iif stable isotopes* t ieholds a Ph*O* front Harvard University.

Vu B

Exploring rocks at Wumiao. Anhui Province. China, participants of the Third International Field Symposiumreceive some attention from villagers. (Photo by Doug Rumble.)

brought them back to the surface. It isremarkable that the lavas survived suchadventures with evidence of theirsurface origin still more or less intact.

The phenomena of ultra-high-pressure metamorphism was recognizedlittle more than a decade ago with thediscovery of minerals stable at pressuresfar higher than those previouslycalibrated in crustal rocks. The high-pressure form of quartz, the mineralcoesite, for example, was found inquartzite by Christian Chopin in 1984.Newly crystallized microdiamonds wereidentified in metamorphosed sedimentsby Nick Sobolev and Vladimir Shatskyin 1990. •

A surprising feature of ultra-high-pressure metamorphism is the huge sizeof its outcrop areas. Thousands of

square kilometers in central and easternChina are underlain by coesite-bearingsediments and volcanics. This areacorresponds to the faulted margins ofthe pre-Cambrian Sino-Korean andYangtze continents. Other belts ofultra-high-pressure rocks are foundalong continental margins (such as inwestern Norway), in continental suturezones on the Siberian platform, and inthe Alps, where ancient Africa andEurope collided. Only events as dra-matic as the collision of continents andthe stacking of continental plates oneupon the other could lead to the deepburial required to produce coesite anddiamond in rocks of surface origin.

Following our 1994 discovery, 1secured funds from the U. S. NationalScience Foundation to join colleagues

'Mantle xenohths, winch may contain k»th a>esite and diamond, are excluded by definition from UHP metamor-fhisin because of differences in origin. Mantle xcnohths are brought to Earths surface by volcanic eruptions. Manywere nppeJ explosively out uf the mantle dt much greater depths than the deepest limit of UHP metamorphism,

• YJ \K IX

J. G. (Louie) Liou and Ruth Y. Zhang(Stanford University) and Bolin Congand Qingchen Wang (Chinese Acad-emy of Sciences, Beijing) to map theanomaly geologically and to obtainadditional samples. Field work wassuccessfully undertaken in China inAugust and September of 1995, concur-rent with the Third International FieldSymposium there.

Shortly after returning from China, Icompleted building a new analyticalinstrument, the ultraviolet (UV) laserisotope microprobe, at the GeophysicalLaboratory. The new instrument makesprospects for the project very favorable.Using it, we can analyze small spots foroxygen isotopes on polished surfaces ofeclogite samples. The measurement ofoxygen isotope ratios in minerals givesa sensitive record of the origins ofwaters, be they from the surface, as inthe rainwater eclogites, or from greaterdepth in the crust or mantle. The UVlaser microprobe is being used not onlyto map the distribution of rainwater inultra-high-pressure metamorphic rocksbut also to detect possible contamina-tion by waters from other sources.

Although the Qinglongshan oxygenisotope anomaly has ephemeral interestas a possible entry in the GuinnessBook of World Records as the world'smost IHO depleted eclogite, the datahave potential for wider application.

Our preliminary results reveal thatthe Qinglongshan anomaly extends atleast two kilometers from the discoveryoutcrop. The eclogites, quartzites,gneisses, and calcite veins in the areaall have unusually low IH0/ifO values,though not all of the rocks within the

zone are as low in l8O as those of thediscovery site. The areal extent ofdepleted 1HO shows that the destructiveprocesses of faulting, subduction, anduplift did not succeed in fragmentingthe ancient geothermal system. Thepiece of crust hosting the geothermalsystem remains today coherent andrecognizable.

The Qinglongshan data also havesome bearing on a much debatedquestion: How much free water canoccur under ultra-high-pressure condi-tions, and in what physical state does itoccur? The phrase 'free water" refers tominute amounts of water wetting grainboundaries, not to water bound insidehydrous ultra-high-pressure minerals,such as phengite or epidote. Weobserve that minerals in eclogite andquartzite separated by less than twometers have the same oxygen isotoperatios. Minerals from rocks separated bydistances of ten meters or more,however, have dissimilar ratios. Theseresults suggest that water was absentbeyond a thin film trapped along grainboundaries and, further, that the waterthat was present was not free to infil-trate more than a few meters.

A final surprise from Qinglongshanis that rocks subducted to 80 kilometersdepth could have significance asindicators of Earth's past climate. Thenegative lHO values could only havecome from rain or snow at cold lati-tudes. The alteration of basaltic lavasmust have taken place in a geothermalsystem located in the far north or southon a Paleozoic or pre-Cambrian Earththat, like today, had cold poles and awarm equator.

Y i •

• Personnel •Research Staff

Francis R. Boyd, Jr.1

George D. Cody2

Ronald E. CohenYingwei Fei?

Larry W. FingerMarilyn L. FogelJohn D. FrantzR Edgar HareRobert M. HazenRussell J. HemleyT. Neil IrvineHo-kwang MaoBj0rn O. MysenCharles T. Prewitt, DirectorDouglas Rumble IIIDavid VirgoHatten S. Yoder, Jr., Director Emeritus

Cecil and Ida Qreen SeniorFellow

Frank Press4

Senior Fellows and Associates

Peter M. Bell, Adjunct Senior ResearchScientist

Constance Bertka, National Aeronautics andSpace Administration and Center for HighPressure Research (CHiPR) Associate

Paula Davidson, Department of Energy (DOE)Associate

Yingwei Fei, Senior Research Associate^Glenn A. Goodfriend, Senior Postdoctoral

Associate, National Science Foundation(NSF)

Jingzhu Hu, Research Technician (NSF)Mark D. Kluge, Research Physicist (NSF)*5

Igor Mazin, NSF and CHiPR Associate6

Jinfu Shu, Research Technician (CHiPR)Chang-Sheng Zha, Research Technician

(CHiPR)

Postdoctoral Fellows andResearch Associates

Carmen Aguilar, NSF Associate7

David R. Bell DOE Associate

Jennifer Blank, Carnegie FellowRobert T. Downs, NSF AssociateJames Farquhar, Carnegie Fellow8

Daniel J. Frost, CHiPR Associate9

Alexander Goncharov, Carnegie FellowTahar Hammouda, CNRS-PICS and Carnegie

Fellow12

Iris Inbar, Office of Naval Research (ONR)Associate10

Joel J. Ita, NSF AssociateBeverly Johnson, Carnegie FellowVictor Kress II, CHiPR AssociatePeter Lazor, CHiPR Associate6

Ming Li, CHiPR Associate10

Wei Li, CHiPR Associate1 *Ren Lu, NSF Associate14

Gotthard Saghi-Szabo, ONR Associate15

Thomas A. Schindelbeck, DeutscheForschungsgemeinschaft Fellow16

Guoyin Shen, CHiPR AssociateLarry Solheim, Carnegie Fellow417

Madduri S. Somayazulu, NSF Associate18

Viktor Struzhkin, NSF and CHiPR AssociateMark A. Teece, Carnegie Fellows

John C. VanDecar, Harry Oscar Wood Fellow4

Michael J. Walter, CHiPR Associate19

Cecily J. Wolfe, NASA Associate and HarryOscar Wood Fellow420

Hexiong Yang, Hazen Gift21

Predoctoral Fellows andResearch Associates

Pamela G. Conrad, Carnegie FellowJulie Kokis, NSF Associate6

Jennifer Linton, CHiPR Associate8

Fioreila Simoni, NSF Associate22

David M. Teter, CHiPR Associate

Research Interns

Mark Acton, Montgomery Blair High Schtxilffs

Aaron Andalman, Stanford University2'Adam Blackman, Bethesda-Chevy Chase

High SchoolCindy T. Cordero, George Washington

University2S

Maura Green, Bethesda-Chevy Chase:r'Marc Hudacsko, University of Maryland*' 'Elizabeth James, Wesleyan University-'7

Eran Karmon, Pomona

140 CARNEGIE INSTITUTION • YEAR BOOK 95

Boris Kiefer, Georgia Institute of Technology29

John Kim, Montgomery Blair5

Billy Lee, Montgomery Blair5

Lisa McGill, Cornell University29

Sehastien Merkel, Ecole Normal Superieure,Lyon, France^0

David Stockman, Montgomery Blair5

Elizabeth Stranges, Montgomery Blair29

Jeremy Sturm, Osborn Park29

Benjamin Van Mooy, Georgetown DaySchool"

Jacob Waldbauer, Georgetown Day School29

Gamunu Wijetunge, Montgomery Blair29

Emily Yourd, George Washington University^2

Supporting Staff

John R. Almquist, Library VolunteerAndrew J. Antoszyk, Shop ForemanMaceo T. Bacote, Engineering Apprentice4

Alessandra Barelli, Research TechnicianBobbie L Brown, Instrument MakerStephen D. Coley, Instrument MakerH. Michael Day, Facilities Manager4

Roy R. Dingus, Building Engineer4

Pablo E. Esparza, Maintenance Technician4

David J. George, Electronics TechnicianChristos G. Hadidiacos, Electronics EngineerShaun J. Hardy, Librarian4

Marjorie E. Imlay, Assistant to the DirectorWilliam E. Key, Building Engineer4

Lucia Lazorova, Library VolunteerD. Carol Lynch, Executive Secretary4

Paul Meeder, Administrative AssistantLawrence B. Patrick, Maintenance

Technician4

Pedro J. Roa, Maintenance Technician4

Roy E. Scalco, Engineering Apprentice4

Susan A. Schmidt, Coordinating SecretaryJohn M. Straub, Business ManagerMark Wah, Instrument MakerMerri Wolf, Library Technical Assistant4

Visiting Investigators

John V Badding, Pennsylvania State UniversityNabil Z. Boctor, Washington, D.C.Alison Brooks, George Washington UniversityBen Burton, National Institute of Standards and

Technology (NIST)Jean Dubessy, Centre de Recherches sur la

Geologie des Matieres Premieres Mineraleset Energetiques, Vandoeuvre-Les-Nancy,France

Thomas S. Duffy, University of ChicagoJoseph Feldman, Naval Research LaboratoryReto Giere, University of Basel, SwitzerlandHans G. Huckenholz, Mineralogisch-

Petrographisches Inst. der Ludwig-Maximilians-Univ. Miinchen

Donald G. Isaak, University of California, LosAngeles

Deborah Kelley, University of WashingtonAllison M. Macfarlane, George Mason

UniversityRyan P. McCormack, NISTCharles Meade, National Research Council,

Washington, D.C.Nicolai P. Pokhilenko, Institute of Mineralogy

and Petrology, Novosibirisk, RussiaRobert K. Popp, Texas A&LM UniversityAnil K. Singh, National Aerospace Laborato-

ries, Bangalore, IndiaNicolai V. Sobolev, Institute of Mineralogy and

Petrology, Academy of Sciences,Novosibirisk, Russia

Lars Stixrude, Georgia Institute of TechnologyNoreen C. Tuross, Smithsonian InstitutionDavid von Endt, Smithsonian InstitutionQingchen Wang, Chinese Academy of SciencesHak Nan Yung, Chinese Academy of Sciences,

GuangzhouRu-Yuan Zhang, Stanford UniversityYi-Gang Zhang, Academia Sinica, ChinaGuangtian Zou, Jilin University, China

'Retired June 30, 1996; appointedConsultant July 1, 1996

-Appointed Staff MemberSeptember 1, 1995

^Appointed Staff Member July 1,19%; Senior ResearchAsstHjate to June 30, 1996

•*Jomt appointment with Depart-ment or Terrestrial Magnetism

To September 1, 1WTo lime 30, W6

Fn<m September 1, 1^5Fr. »iii Februan \ 1^6

"To September 30, 199511 From January 16, 1996"From July 1, 1995"From March 29, 1996'•From March 23, 1996lsFrom January- 2, 1996"••From March 5, 1996'-To November 30, 1995"•To April 30, 1996"To July 15, 1995-vFrom January 1, 1996-'From August 1, 1995-To October 1, 1995; From

May 1 to August 30, 1996•"From June 15, 1996-4To August 22, 1995^From July 15, 1995 to August 30, 1995-'"From )uly 10 to August 31, 1995; From

June 1, 1996-Tojulv 30, 1995-""From June 1 to August 18, 1995; From

June 10, 1996:'From June 1, 19%-From Ma\ 1, TO6"To August 15, 1995ToJuU 31, 1W

141

• Bibliography •Reprints of the numbered publications listedbelow are available, except where noted, at nocharge from the Librarian, GeophysicalLaboratory, 5251 Broad Branch Road, N.W,Washington, D.C. 20015-1305, U.S.A. Pleasegive reprint number(s) when ordering.

2526 Abbott, J. T., G. L. Ellis, and G. A.Goodfriend, Chronometric and integrityanalyses using land snails, in NRHP Signifi-cance Testing of 57 Prehistoric Archeological Siteson Fort Hood, Texas, Volume II, J. T. Abbottand W. N. Trierweiler, eds., pp. 801-814, U.S.Army Fort Hood Archeological ResourceManagement Series Research Report No. 34,Fort Hood, Texas, 1995. (No reprintsavailable.)

2555 Alberto, H.V., J. L. Pinto da Cunha, B. O.Mysen, J. M. Gil, and N. Ayres de Campos,Analysis of Mossbauer spectra of silicateglasses using a two-dimensional Gaussiandistribution of hyperfine parameters, J. Non-Cryst. Solids 194,48-57, 1996.

2577 Bassett, W. A., T.-C Wu, I.-M. Chou, H. T.Haselton, Jr., J. Frantz, B. O. Mysen, W.-LHuang, S. K. Sharma, and D. Schiferl, Thehydrothermal diamond anvil cell (HDAC)and its applications, in Mineral Spectroscopy: ATribute to Roger G. Burns, M. D. Dyar, C.McCammon, and M. W. Schaefer, eds., pp.261-272, Special Publication No. 5,Geochemicai Society, Houston, 1996.

Bertka, C. M., and Y. Fei, Constraints onthe mineralogy of an iron-rich Martian mantlefrom high-pressure experiments, Planet. SpaceSci., in press.

. Bertka, C. M., and Y. Fei, Mineralogy of theMartian interior up to core-mantle boundarypressures,). Geophys, Res., in press.

2585 Bono, R. E., G. D. Cody> S. L Diekman, D.C. French, N. Gopalsami, and P. Rizo, Three-dimensional magnetic resonance of materials,Solid State NucLMagn. Reson. 6, 389-402,1996.

2584 Bouillard, J. X., M. Enzien, R. W. Peters, J.Frank, R. E. Botto, and G. D. Cody, Hydrody-namics of foam flows for in situ bioremedi-ation of DNAPL-contaminated subsurface, inApplied Bioremediation of Petroleum Hydrocar*bans, R. E. Hinchee et al, eds., pp. 311-317,Battelle Press, Columbus, Ohio, 1995. (Noreprints available.)

2582 Boyd, F R., Origins of peridotite xenoliths:

major element considerations, in High Pressureand High Temperature Research on Lithosphereand Mantle Materials, M. Mellini et al, eds.,pp. 89-106, Proceedings of the InternationalSchool Earth and Planetary Sciences, Siena,Italy, 1996.

. Boyd, F. R., N. P. Pokhilenko, D. G.Pearson, S. A. Mertzman, N. V. Sobolev, andL. W. Finger, Composition of the Siberiancratonic mantle: evidence from Udachnayaperidotite xenoliths, Contrib. Mineral. Petrol.,in press.

2537 Bundy, F. P., W. A. Bassett, M. S. Weathers,R. J. Hemley, H. K. Mao, and A. L.Goncharov, The pressure-temperature phaseand transformation diagram for carbon;updated through 1994, Carbon 34, 141-153,1996.

2589 Cody, G. D., and R. E. Botto, Magneticresonance microscopy and the dynamics ofsolvent transport in coal, in Proceedings of theHokkaido Coal Conference, pp. 8-13, HokkaidoNational Industrial Research Institute,Sapporo, Japan, 1996.

Cody, G. D., R. E. Botto, H. Ade, and S.Wirick, The application of soft x-ray micros-copy to the in-situ analysis of sporinite in coal,Int. J. Coal Geol., in press.

2569 Cohen, R. L, Periodic slab LAPWcomputations for ferroelectric BaTiO,, J. Phys.Chern. Solids 57, 1393-1396, 1996.

Cohen, R. E., Surface effects in ferroelec-trics: periodic slab computations for BaTiO,,FerroelectricSj in press.

_ Cohen, R. E., and J. Weitz, The meltingcurve and premelting of MgO, in High"Pressure'Temperature Research: Properties ofEarth and Planetary Materials, M. H.Manghnani and Y. Syono, eds., AmericanGeophysical Union, Washington, D.C., inpress.

Downs, R. T, A. Andalman, and M.Hudacsko, The coordination numbers of Naand K atoms in low albite and ink r id me a*determined from a procrystal electron tlensitvdistribution, Am, Miner til., in press.

25^2 Downs, R. T., C. S. Zha, T. S. Duffy, anJ LW. Finger, The equation of state of tW^tentcto 17.2 GPa and effects of pressure media, AmMineral. SJ, 51-55, 19%,

2551 Ellis, Ci, L, Ci. A. UudfnenJ, J. T AHvtt.P. E. Hare, ,mJ IX W. Yon Endt, »W^menr. -1mtegntv and jj;e»»chronnL>«\ ct archt^lt j;u.v,

142 C\l\SL ,11 K-TSTl 11 \ • Yl Mi ,05

sites using amino acid racemization in landsnail shells: examples from central Texas,Geoarchaeology 11, 1 8 9 - 2 1 3 , 1996.

2576 Fei, Y., Crystal chemistry of FeO at highpressure and temperature, in Mineral Spectros-copy: A Tribute to Roger G. Burns, M. D. Dyar,G McCammon, and M. W. Schaefer, eds., pp.243-254, Special Publication No. 5,Geochemical Society, Houston, 1996.

2561 Fei, Y., and C. T. Prewitt, High-pressurebehavior of iron sulfide, in Covalent CeramicsIII: Science and Technology of Non-Oxides, A. EHepp et aL, eds., pp. 223-228, SymposiumProceedings 410, Materials Research Society,Pittsburgh, 1996.

2543 Fei, Y., Y. Wang, and L. W. Finger, Maxi-mum solubility of FeO in (Mg,Fe)SiO,-perovskite as a function of temperature at 26GPa: implication for FeO content in the lowermantle, J. Geophys. Res. 101, 11525-11530,1996.

2580 Ganguly, J., S. Chakraborty, T. G. Sharp,and D. Rumble III, Constraint on the timescale of biotite-grade metarnorphism duringAcadian orogeny from a natural garnet-garnetdiffusion couple, Am. Mineral. 81, 1208-1216, 1996.

2528 Giere, R., Formation of rare earth mineralsin hydrothermal systems, in Rare EarthMinerals: Chemistry, Origin and Ore Deposits,A. P. Jones, E Wall, and C. X Williams, eds.,Ch. 5, pp. 105-150, Chapman & Hall,London, 1996. (No reprints available.)

2586 Giere, R., and A. Stahel, eds., Swiss Bulletinof Mineralogy and Petrology Special Issue:Transition from Penninic to Anstroalpine Units inthe Bergell Alps, Schweiz. Mineral. Petrogr. Mitt.76, no. 3, 1996. (Available for purchase fromthe publisher.)

2587 Giere, R., and A. Stahel, Transition fromPenninic to Austroalpine units in the BergellAlps: introduction, Schweiz* Mineral Petrogr.Mitt. 76, 325-328, 1996.

_ Goncharov, A. E, J. H. Eggert, I. I. Mazin,R. J. Hemley, and H. K. Mao, Ramanexcitations and orientational ordering indeuterium at high pressure, Phys. Rev. B, inpress.

2567 Goncharov, A. E, 1.1. Mazin, J. H. Eggert,R. J. Hemley, and H. K. Mao, Orientationalorder, disorder, and possible glassy behavior indense deuterium, in High Pressure Science andTechnok>gy: Proceedings of the Joint XVAIR APT ami XXXlll EHPRG InternationalConference, W. A. Trzeciakowski, ed.t pp. 5 ^ -515, World Scientific, Singapore, 1996.

2564 Goncharov, A, E, M. Somayazulu, V. V,Struzhkin, R. I Hemley, and H. K. Mao, New

high-pressure low-temperature phase ofmethane, in Proceedings of the FifteenthInternational Conference on Raman Spectros-copy, S. A. Asher and R B. Stein, eds., pp.1042-1043, John Wiley (Si Sons, Chichesterand New York, 1996.

2556 Goncharov, A. E, V. V Struzhkin, M. S.Somayazulu, R. J. Hemley, and H. K. Mao,Compression of ice to 210 GPa: infraredevidence for a symmetric hydrogen-bondedphase, Science 273, 218-220, 1996.

2553 Gong, W. L, L. M. Wang, R. C. Ewing, andY. Fei, Surface and grain-boundaryamorphization: thermodynamic melting ofcoesite below the glass transition temperature,Phys. Rev. B 53, 2155-2158, 1996.

2545 Goodfriend, G. A., J. Brigham-Grette, andG. H. Miller, Enhanced age resolution of themarine Quaternary record in the Arctic usingaspartic acid racemization dating of bivalveshells, Quat. Res. 45, 176-187, 1996.

2552 Goodfriend, G. A., R. A. D. Cameron, LM. Cook, M. A. Courty, N. Fedoroff, E.Livett, and J. Tallis, The Quaternary eoliansequence of Madeira: stratigraphy, chronology,and paleoenvironmental interpretation,Palaeogeogr. Palaeoclimatol. Palaeoecol. 120,195-234, 1996. (No reprints available.)

Goodfriend, G. A., K. W. Flessa, and P. E.Hare, Variation in amino acid epimerizationrates and amino acid composition among shelllayers in the bivalve Chione from the Gulf ofCalifornia, Geochim. Cosmochim. Acta, inpress.

. Goodfriend, G. A., and S. J- Gould,Paleontology and chronology of two evolu-tionary transitions by hybridization in theBahamian land snail Cerion, Science, in press.

2535 Goodfriend, G. A., and D. J. Stanley,Reworking and discontinuities in Holocenesedimentation in the Nile Delta; documenta-tion from amino acid racemization and stableisotopes in mollusk shells, Mar. Geol. 129,271-283, 1996.

2542 Hazen, R. M, R. T. Downs, and L. W.Finger, High-pressure crystal chemistry ofLiScSiO4: an olivine with nearly isotropiccompression, Am. Mineral. 81, 327-334,1996.

2549 Hazen, R. M., R. X Downs, and L W.Finger, High-pressure framework silicates,Science 272, 1769-1771, 1996.

2571 Hazen, R. M., and A. Navrotsky, Effects ofpressure on order-disorder reactions, Am.Mineral. SL 1021-1035, 1996.

2S2Q Hazen, R. M., and J. Trefil, The PhysicalSciences: an Integrated Approach, John Wiley &Sims, New York, 672 pp , 1996. (Available for

YiAf-

purchase from the publisher.)

. Hemley, R. J., Properties of matter at highpressures and temperatures, in History of theGeosciences: An Encyclopedia, G. A. Good, ed.,Garland Publishing, New York, in press.

2541 Hemley, R. J., and N. W. Ashcroft, High-pressure physics: shocking states of matter,Nature 380, 671-672, 1996.

2558 Hemley, R. J., and R. E. Cohen, Structureand bonding in the deep mantle and core,Phil. Trans. Roy. Soc. London A 354, 1461-1479, 1996.

2563 Hemley, R. J., and H. K. Mao, High-pressureRaman spectroscopy: new windows on matterunder extreme conditions, in Proceedings of theFifteenth International Confererence on RamanSpectroscopy, S. A. Asher and P. B. Stein, eds.,pp. 1032-1033, John Wiley & Sons,Chichester and New York, 1996.

Hemley, R. J., and H. K. Mao, Static high-pressure effects in solids, in Encyclopedia ofApplied Physics, VCH Publishers, New York, inpress.

Hemley, R. J., and H. K. Mao, Densemolecular hydrogen: order, disorder, andlocalization, J. Non-Cryst. Solids, in press.

2533 Hemley, R. J., H. K. Mao, A. F. Goncharov,M. Hanfland, and V. Struzhkin, Synchrotroninfrared spectroscopy to 0.15 eV of H2 and D:

at megabar pressures, Phys. Rev. Lett. 76,1667-1670, 1996.

2550 Holtz, E, J.-M. Beny, B. O. Mysen, and M.Pichavant, High-temperature Ramanspectroscopy o( silicate and aluminosilicatehydrous glasses: implications for waterspeciation, Chem. Geol. 128, 25-39, 1996.

Ilchik, R. P., and D. Rumble III, Sulfur,carbon and oxygen systematics duringdiagenesis and fluid infiltration in the CreedeCaldera, Colorado, in Preliminary ScientificResults of the Creede Caldera ContinentalScientific Drilling Program, P. M. Bethke, ed.,Ch. 11, U.S. Geol. Surv. Open-File Report 94-260, in press.

2531 Inbar, L, and R. E. Cohen, Comparison ofthe electronic structures and energetics offerroelectric LiNbO.and LiTaO , Phys. Rev. B53, 1193-1204, 1996.

Inbar, L, and R. E. Cohen, Origin offerroelectricity in LiNhO, and LiTaO^Ferroelectries, in press.

Irvine, T. R, J. C. 0. Andersen, C. K.Brooks, and J. R. Wilson, Included Hocks(and blocks within blocks) in the SkaergaardIntrusion, East Greenland, Geol. Soc. Am.Bull, in press.

Johnson, B. J,, and G. H. Miller, Archaeo-

logical applications of amino acid racemizationdating: a review, Archaeometry, in press.

2554 Kingma, K. J., H. K. Mao, and R. J. Hemley,Synchrotron x-ray diffraction of SiO, tomultimegabar pressures, High Pressure Res. 14,363-374, 1996.

Kress, V, Thermochemistry of sulfide liquidsI: the system O-S-Fe at 1 bar, Contrib. Mineral.Petrol., in press.

Kruger, M. B., and C. Meade, High pressurestructural study of Gel4, Phys. Rev. B, in press

2548 Longhi, J., and C. M. Bertka, Graphicalanalysis of pigeonite-augite liquidus equilibria,Am. Mineral. 81, 685-695, 1996.

2573 Loubeyre, P., R. LeToullec, D. Hausermann,M. Hanfland, R. J. Hemley, H. K. Mao, and L.W. Finger, X-ray diffraction and equation ofstate of hydrogen at megabar pressures, Nature383, 702-704, 1996.

Lumpkin, G. R., and R. Giere, Applicationof analytical electron microscopy to the studyof radiation damage in natural zirconolite,Micron, in press.

2547 Mao, H. K., and R. J. Hemley, Energydispersive x-ray diffraction o( micro-crystals atultrahigh pressures, High Pressure Res. 14,257-267, 1996.

2557 Mao, H. K., and R. J. Hemley, Experimentalstudies of Earth's deep interior: accuracy andversatility of diamond-anvil cells, Phil. Trans.Roy. Soc. London A 354, 1315-1332, 1996.

2566 Mao, H. K., and R. J. Hemley, Solidhydrogen at ultrahigh pressures, in HighPressure Science and Technology: Proceedings ofthe joint XV A/RAPT and XXXIII EHPRGInternational Conference, W. A. Trzeciakowski,ed., pp. 505-510, World Scientific, Singapore,1996.

2570 Mao, H. K., J. Shu, Y. Fei, J. Hu, and R. J.Hemley, The wiistite enigma, Phys. EarthPlanet. Inter. 96, 135-145, 1996.

Mazin, 1.1., and R. E. Cohen, Notes on thestatic dielectric response function in thedensity functional theory, Ferroekctrics, inpress.

2581 Mazin, I. L, and A. A. Goluhov, Impurityscattering in highly anisotropic superconduc-tors and interband sign reversal of the orderparameter, in Spectroscopic Studies of Supercon-ductors, I. Bozovic and D. van der Marel, eds.,pp. 441-447, SPIE Proceedings Vol. 2696,SPIE, Bellingham, Wash., 1996. (No reprintsavailable.)

2560 McMillan, P. F, J. Duhessy, and R. Hemley,Applications in earth, planetary and environ-mental sciences., in Rainan Microscopy:Developments and Applications, G, Turrcll and

144 • YEAR FVOK 95

J. Corset, eds., Ch. 7, pp. 289-365, AcademicPress, London and San Diego, 1996. (Noreprints availahie.)

2575 McMillan, P. E, R. J. Hemley, and P. Gillet,Vibrational spectroscopy of mantle minerals,in Mineral Spectroscopy: A Tribute to Roger G.Burns, M. D. Dyar, C. McCammon, and M.W. Schaefer, eds., pp. 175-213, SpecialPublication No. 5, Geochemical Society,Houston, 1996.

2574 Mysen, B., Haploandesitic melts atmagmatic temperatures: in situ, high-temperature structure and properties o{ meltsalong the join K2Si4O9-K2(KAl)4O, to 1236- Cat atmospheric pressure, Geochim. Cosmochim.Acta 60, 3665-3685, 1996.

.Mysen, B., Aluminosilicate melts: structure,composition, and temperature, Contrib.Mineral. Petrol., in press.

Mysen, B., Silicate melts and glasses: theinfluence of temperature and composition onthe structural behavior of anionic units, in K.Yagi 80th Birthday Commemoration Volume, A.Gupta, ed., Indian Academy of Sciences, inpress.

Mysen, B., Transport configurationalproperties of silicate melts: relationship tomelt structure at magmatic temperatures, Phys.Earth Planet. Inter,, in press.

2546 Neuville, D. R., and B. O. Mysen, Role ofaluminum in the silicate network: in situ,high-temperature study of glasses and melts onthe join SiO2-NaAlO2, Geochim. Cosmochim.Acta 60, 1727-1737, 1996.

2559 Pennock, J. R., D. J. Velinsky, J. M. Ludlam,J. H. Sharp, and M. L. Fogel, Isotopicfractionation of ammonium and nitrate duringuptake by Skeletonema costatum: implicationsfor d!5N dynamics under bloom conditions,Limnol Oceanogr. 41, 451-459, 1996.

2525 Popp, R. K., D. Virgo, and M. W. Phillips, Hdeficiency in kaersutitic amphiboles: experi-mental verification, Am. Mineral. 80, 1347-1350, 1995.

2583 Qadri, S. B., J. Yang, B. R. Ratna, E. ESkelton, and J. TL. Hu, Pressure inducedstructural transititions in nanometer sizeparticles of PbS, Appl Phys. Lett. 69, 2205-2207, 1996.

2544 Richer, P., B. O. Mysen, and D. Andrault,Melting and premelting of silicates: Ramanspt*etroN€opy and X-ray diffraction of Li,SiO(

and Na.SiO,, Phys. Chem. Minerals 23, *157-172, 19%.

_ _ _ Rumble, DM and Z* D. Sharp, Lasermien analysis of silicates for !\)/ i :O/ ! l 'O and ofcarbonates tor ^O/^O and pC/ ! jC, in Stxiety«»f Eamamic Gco/ogjsts, Stu/rt Course NWw, in

press.Saghi-Szabo, G., and R. E. Cohen, Long-

range order effects in Pb(Zr,/:Ti1/2)O,,Ferroelectrics, in press.

2590 Saxena, S. K., L. S. Dubrovinsky, P. Lazor, Y.Cerenius, P. Haggkvist, M. Hanfland, and J.Hu, Stability of perovskite (MgSiO,) in theEarth's mantle, Science 274, 1357-1359, 1996.

2588 Schmid, S. M., A. Berger, C. Davidson, R.Giere, J. Hermann, P. Nievergelt, A. Puschnig,and C. Rosenberg, The Bergell Pluton(southern Switzerland, northern Italy):overview accompanying a geological-tectonicmap of the intrusion and surrounding countryrocks, Schweiz- Mineral. Petrogr. Mitt. 76, 329-355, 1996. (No reprints available.)

2540 Shen, G., H. K. Mao, and R. J. Hemley,Laser-heated diamond anvil cell technique:double-sided heating with multimodeNd:YAG laser, in Advanced Materials 196,Proceedings of the 3rd NIRIM InternationalSymposium on Advanced Materials, pp. 149-152, National Institute for Research inInorganic Materials, Tsukuba, Japan, 1996.

2534 Somayazulu, M. S., L. W. Finger, R. J.Hemley, and H. K. Mao, High-pressurecompounds in methane-hydrogen mixtures,Science 271, 1400-1402, 1996.

2527 Soos, Z. G., J. H. Eggert, R. J. Hemley, M.Hanfland, and H. K. Mao, Charge transfer andelectron-vibron coupling in dense solidhydrogen, Chem. Phys. 200, 23-39, 1995.

2578 Sperlich, R., R. Giere, and M. Frey,Evolution of compositional polarity andzoning in tourmaline during progrademetamorphism of sedimentary rocks in theSwiss Central Alps, Am. Mineral. 81, 1222-1236, 1996.

Stafford, T. S., M. L. Fogel, K. Brendel, andP. E. Hare, Late Quaternary paleoecology ofthe southern high plains based on stablenitrogen and carbon isotope analysis of fossilBison collagen, in The Archaic of the SouthernNorth American Deserts, H. Shafer, D. L.Carlson, and K. D. Sobolik, eds., Texas A&MPress, College Station, in press.

2572 Stixrude, U R- E. Cohen, R. Yu, and H.Krakauer, Prediction of phase transition inCaSiO^ perovskite and implications for lowermantle structure, Am. Mineral 8h 1293—1296, 1996.

Stixrude, LM E. Wasserman, and R. E.Cohen, First-principles investigations of solidiron at high pressure and implications for theEarth's inner core, in High-IVessMre-Tt'mlvra*ture Research: Properties i4^an^ an^ PlanetaryMaterials< M. H, Manghnani dnd Y. Syoni>,eds., American Geuph\sical UnK»n, W

ton, D.C., in press.

2568 Struzhkin, V. V, Yu. A. Timofeev, R. T.Downs, R. J. Hemley, and H. K. Mao, TC(P)from magnetic susceptibility measurements inhigh temperature superconductors:YBa2CuO3O7.x and HgBa2Ca2Cu,O8+x, in HighPressure Science and Technology: Proceedings ofthe Joint XV AIRAPT and XXXIIJ EHPRGInternational Conference, W. A. Trzeciakowski,ed., pp. 682-684, World Scientific, Singapore,1996.

Tera, E, R. W. Carlson, and N. Z. Boctor,Radiometric ages oi basaltic achondrites andtheir relation to the early history of the solarsystem, Geochim. Cosmochim. Acta, in press.

2536 Teter, D. M, and R. J. Hemley, Low-compressibility carbon nitrides, Science 271,53-55, 1996.

2579 Thibault, Y., and M. J. Walter, Theinfluence of pressure and temperature on themetal-silicate partition coefficients of nickeland cobalt in a model Cl chondrite andimplications for metal segregation in a deepmagma ocean, Geochim. Cosmochim. Acta 59,991-1002, 1995.

2565 Vos, W L, L. W. Finger, R. J. Hemley, andH. K. Mao, Pressure dependence of hydrogenbonding in a novel HX)-H2 clathrate, Chem.Phys. Lett. 257, 524-530, 1996.

2530 Waiter, M. J., and Y. Thibault, Partitioningof tungsten and molybdenum between metallicliquid and silicate melt, Science 270, 1186—1189, 1995.

2538 Wasserman, E., L. Stixrude, and R. E.Cohen, Thermal properties of iron at highpressures and temperatures, Phys. Rev. B 53,8296-8309, 1996.

Yang, H., R. M. Hazen, R. T. Downs, and L.W Finger, Structural change associated withthe incommensurate-normal phase transitionin akermanite, Ca2MgSi207, at high pressure,Phys. Chem. Minerals, in press.

2539 Yoder, H. S., Jr., Joseph Paxson Iddings,January 21, 1857-September 8, 1920, inBiographical Memoirs of the National Academy ofSciences, Vol. 69, pp. 115-147, NationalAcademy Press, Washington, D.C., 1996.(Available for purchase from the publisher.)

Yoder, H. S., Jr., Italian volcanology:Geophysical Laboratory contributions, 1905-1965, in Volcanoes and History: Proceedings ofthe XXth Symposium oflNHlGEO, in press.

Young, E. D., D. Virgo, and R. K. Popp,Eliminating closure in mineral formulae withspecific application to amphiboles, Am.Mineral., in press.

Yui, T. F, D. Rumble, C. H. Chen, and C.H. Lo, Stable isotope characteristics ofeclogites from east-central China: two stagesof meteoric water-rock interactions, Chem.Geol., in press.

2562 Zha, C. S., T. S. Duffy, R. T. Downs, H. K.Mao, and R. J. Hemley, Sound velocity andelasticity of single-crystal forsterite to 16 GPa,J. Geophys. Res. 101, 17535-17545, 1996.

146 CARNEUH INSTITUTION • YEAR BOOK 95

• Administrative Personnel •

Carnegie InstitutionAdminis tratixm1530 P Street, N.W.Washington, D.C. 20005

Lloyd Allen, Building Maintenance SpecialistSharon Bassin, Secretary to the PresidentSherill Berger, Research Assistant, Institu-

tional and External AffairsRay Bowers, Editor and Publications Officer1

Gloria Brienza, Budget and ManagementSpecialist

Don A. Brooks, Building MaintenanceSpecialist

Cady Canapp, Human Resources andInsurance Manager

Margaret Charles, SecretaryPatricia Craig, Editor and Publications Officer2

Nicholas DeCarlo, Grants and OperationsManager

Susanne Garvey, Director, Institutional andExternal Affairs

Ann Keyes, Payroll CoordinatorJennifer King, Assistant Editor*Jeffrey Lightfield, Financial AccountantJohn J. Lively, Director, Administration and

FinanceTrong Nguyen, Financial AccountantDanielle Palermo, Administrative Assistant,

Grants and Operations4

Loretta Parker-Brown, AdministrativeSecretary

Catherine Piez, Systems and Fiscal ManagerArnold Pryor, Facilities and Services

SupervisorMaxine F. Singer, PresidentJohn Strom, Administrative Support AssistantKris Sundback, Financial Manager

Vickie Tucker, Administrative Coordinator/Accounts Payable

Ernest Turner, Custodian (on call)Susan Y. Vasquez, Assistant to the PresidentYulonda White, Human Resources and

Insurance Records CoordinatorJacqueline J. Williams, Assistant to Human

Resources and Insurance Manager

Carnegie Academy for ScienceEducation (CASE)

Natalie Barnes, Mentor Teacher5

Michael J. Charles, CASE InternInes L. Ctfuentes, CASE Program CoordinatorLinda Feinberg, CASE Administrator and

EditorEduardo Gamarra, Mentor Teacher6

Theresa Gasaway, Mentor Teacher6

Patricia Goodnight, Mentor Teacher5

Margaret E. Jackson, Mentor Teacher5

Charles James, Director, Curriculum andInstruction, CASE, and Director, FirstLight

Alida James, CASE Mentor6

Jacqueline Lee, Mentor Teachers

Avis McKinney-Thornas, Mentor Teacher5

Charles Mercer, Mentor Teachers

Sandra B. Norried, MentorRose Marie Patrick, CASE Mentor6

Ollie Smith, Mentor Teacher5

Gregory Taylor, Mentor Teacher and FirstLight Assistant6

Jerome Thornton, Mentor Teacher and FirstLight Assistant5

DeRon Turner, CASE Intern6

Darryll Vann, CASE Mentor*Sue P. White, Mathematics CoordinatorLaurie Young, CASE Mentor6

'Retired May M, 1996-From June I, W6'From June 4, 1996•To October 27, 199STo August 15, 1995'From June 24, 1996

Photo, facing page: Schcx>I teachers participating in the Carnegie Academy for Science Education fCASE)gather in the rotunda of the administration building, July 19%. Since 1994, CASE has conducted summertraining sessions for Washington, D.C. elementary school teachers, offering them Interactive science-teachingskills they can bring back to their classrooms.

• Publications and Special Events •

Publications of the Institution

Carnegie Institution of Washington Year Book 94,

vi + 194 pages, 71 illustrations*December 1995.

Spectra: The Newsletter of the Carnegie Institution,issued in November 1995, March 1996,

and June 1996.

Carnegie Evening 1996,16 pages, 12 illustrations, May 1996.

Publications of the President

Singer, M. E, and P. Berg, The recombinant Hohjoh, H., and M. E Singer, CytoplasmicDNA controversy: twenty years later, Proc. ribonucleoprotein complexes containingNatl Acad. Sri. USA 92, 9011-9013, human LINE-1 protein and RNA, EMBO1995. J. 15, 630-639, 1996.

Singer, M. E, Minireview: unusual reverse Singer, M. E, Assault on science, Thetranscriptases, J. Biol. Chem. 270, 24623- Washington Post, Op ed page, June 26,24626, 1995. 1996.

Carnegie Evening Lecture

Christopher B. Field,Global Change and Terrestrial Ecosystems,

May 2, 1996

Capital Science Lectures

Michael J. Novacek, Evolutionary Trees: FromGobi Dinosaurs to Gene Sequences,October 24, 1995

Donald D. Brown, How Hormones ControlDevelopment, November 28, 1995

Marcia McNutt, The Building of Tibet,December 19, 1995

Irwin Shapiro, Peering at the UniverseThrough Gravitational Lenses, January 30,1996

Arthur E Hebard, Buckminsterfullerene (C^):From Soot to Superconductivity andBeyond, February 20, 1996

Anneila I. Sargent, Other Solar Systems:Searches for Planetary Systems in Forma-tion, March 19, 1996

Carla J. Shatz, Brain Waves and Brain Wiring,April 9,1996

Albert James Hudspeth, How the Ear's WorksWork: The Basis, Loss, and Restoration ofHearing, May 14, 1996

r i ii • YI XK

• Abstract of lMinutes •

of the One Hundred and Fourth Meeting of the Board of Trustees

The Trustees met in the Board Room of the Administration Building on Friday,May 3, 1996. The meeting was called to order by the Chairman, Thomas N.Urban.

The following Trustees were present: Philip H. Abelson, William T. Coleman,Jr., John E Crawford, John Diebold, James D. Ebert, Wallace Gary Ernst, SandraM. Faber, Bruce W. Ferguson, Michael E. Gellert, William T. Golden, DavidGreenewalt, Gerald D. Laubach, John D. Macomber, Richard A. Meserve, FrankPress, David E Swensen, Charles H. Townes, Thomas N. Urban, and Sidney J.Weinberg, Jr. Also present were Caryl P. Haskins, Trustee Emeritus; Maxine ESinger, President; John J. Lively, Director of Administration and Finance; SusanneGarvey, Director of Institutional and External Affairs; Allan C. Spradling, Direc-tor of the Department of Embryology; Charles T. Prewitt, Director of the Geo-physical Laboratory; Sean C. Solomon, Director of the Department of TerrestrialMagnetism; Augustus Oemler, Jr., Director of the Carnegie Observatories; Susan Y.Vasquez, Assistant Secretary; and Marshall Hornblower and William J. Wilkins,Counsel.

The minutes of the One Hundred and Third Meeting, held at the Administra-tion Building on December 14-15, 1995, were approved.

The Chairman notified the Trustees of the death of Garrison Norton. He read amemorial statement in tribute to Mr. Norton and the following resolution wasunanimously adopted:

Be It Therefore Resolved, That the Board of Trustees of the CarnegieInstitution of Washington hereby records its deep sense of loss at thedeath of Garrison Norton.

And Be It Further Resolved, That this resolution be entered on theminutes of the Board of Trustees and that a copy be sent to the family ofMr. Norton.

The reports of the Executive Committee, the Finance Committee, the Em-ployee Benefits Committee, and the Auditing Committee were accepted. On therecommendation of the latter, it was resolved that KMPG Peat Marwick beappointed as public accountants for the fiscal year ending June 30, 1996.

Yi >\K fV'ok^S • C\K\a ii K-TIT1 T:. \ 151

The Bylaws of the Institution were amended. The amended language is given in

the Bylaws printed on pages 153- 159 of this Year Book.

On recommendation of the Nominating Committee, the following were re-

elected for terms ending in 1999: John Diebold, James D. Ebert, Wallace Gary

Ernst, Sandra M. Faber, Bruce W. Ferguson, Kazuo Inamori, Frank Press, and

William I. M. Turner, Jr.

The following were elected for one-year terms: Richard A. Meserve, as chair-man of the Research Committee; John D. Macomber, as Chairman of the Devel-opment Committee; William T Coleman, Jr., as Chairman of the Employee AffairsCommittee; and Philip H. Abelson, as Chairman of the Audit Committee.William L M. Turner, Jr. was appointed Chairman of the Nominating Committeefor a one-year term.

Vacancies in the Standing Committees, with terms expiring in the yearsindicated in parentheses, were filled as follows: Philip H. Abelson (1998), JohnDiebold (1999), Richard E. Heckert (1999), John D. Macomber (1998), William J.Rutter (1997), and Sidney J. Weinberg, Jr. (1999) were elected members of theBudget and Operations Committee. David E Swensen (1998), Robert G. Goelet(1999), William T. Golden (1997), Richard E. Heckert (1999), William I. M.Turner, Jr. (1999), and Sidney J. Weinberg (1998) were elected members of theFinance Committee. William T. Coleman, Jr. (1998), John F. Crawford (1999),Sandra M. Faber (1998), David Greenewalt (1999), and Richard E Heckert(1997) were elected members of the Employee Affairs Committee. Richard A.Meserve (1999), Philip H. Abelson (1997), James D. Ebert (1998), Sandra M.Faber (1997), Bruce W. Ferguson (1998), Michael Gellert (1999), William T.Golden (1998), David Greenewalt (1999), William R. Hearst III (1998), RichardE. Heckert (1999), Kazuo Inamori (1997), Frank Press (1997), and William J.Rutter (1999) were elected members of the Research Committee. John D.Macomber (1999) was elected a member of the Development Committee- PhilipH. Abelson (1997), John Diebold (1999), and Bruce W. Ferguson (1998) wereelected members of the Audit Committee. William I. M. Turner, Jr. (1999), JohnDiebold (1999), Richard A. Meserve (1997), Frank Press (1998), and Sidney J.Weinberg, Jr. (1998) were elected members of the Nominating Committee.

The annual report of the President was received.

To provide tor the operation of the Institution for the fiscal year ending June30, 1997, and upon recommendation of the Executive Committee, the sum of$35,2 38, W2 was appropriated.

IS; i • v. ,t 1'.,-.- : % • V >>' H

• Bylaws of the Institution •As amended May 3, 1996

ARTICLE I

The Trustees

Section 1.1. The Board of Trustees shall consist of up to twenty-seven members as deter-mined from time to time by the Board.

Section 1.2. The Board of Trustees shall be divided into three classes approximately equal innumber. The terms of the Trustees shall be such that those of the members of one class expire atthe conclusion of each May meeting of the Board. At each May meeting of the Board vacanciesresulting from the expiration of Trustees' terms shall be filled by their reelection or election oftheir successors. Trustees so reelected or elected shall serve for terms of three years expiring at theconclusion of the May meeting of the Board in the third year after their election. A vacancyresulting from the resignation, death, or incapacity of a Trustee before the expiration of his orher term may be filled by election of a successor at or between May meetings. A person electedto succeed a Trustee before the expiration of his or her term shall serve for the remainder of thatterm unless the Board determines that assignment to a class other than the predecessor's isappropriate. There shall be no limit on the number of terms for which a Trustee may serve, and aTrustee shall be eligible for immediate reelection upon expiration of his or her term.

Section 1.3. No Trustee shall receive any compensation for his or her services as such.

Section 1.4. Trustees shall be elected by vote of two-thirds of the Trustees present at ameeting of the Board of Trustees at which a quorum is present, subject to compliance withSection 5.9(c) and (d), or without a meeting by written action of all of the Trustees pursuant toSection 4.6.

Section 1.5. If, at any time during an emergency period, there be no surviving Trustee capableof acting, the President, the Director of each existing Department, or such of them as shall thenbe surviving and capable of acting, shall constitute a Board of Trustees pro tern, with full powersunder the provisions of the Articles of Incorporation and these Bylaws. Should neither thePresident nor any such Director be capable of acting, the senior surviving Staff Member of eachexisting Department shall be a Trustee pro tern, with full powers of a Trustee under the Articles ofIncorporation and these Bylaws. It shall be incumbent on the Trustees pro tern to reconstitute theBoard with permanent members within a reasonable time after the emergency has passed, atwhich time the Trustees pro tern shall cease to hold office. A list of Staff Member seniority, asdesignated by the President, shall be kept in the Institution's records.

Section 1.6. A Trustee who resigns or elects not to stand for reelection after having served atleast six years and having reached age seventy shall be eligible for designation by the Board ofTrustees as a Trustee Emeritus. A Trustee Emeritus shall he entitled to attend meetings of theBoard but shall have no vote and shall not be counted for purposes of ascertaining the presenceof a quorum. A Trustee Emeritus may be invited to attend any meeting of a committee of theBoard and to serve as an advisor to any such committee.

ARTICLE II

Officers of the Board

Section 2.1. The officers of the Board of Trustees shall he a Chairman, a Vice-Chairman, anda Secretary, who shall he elected by the Trustees, from the members of the Board, to serve forterms of three years and shall be eligible for reelection. A vacancy resulting from the resignation,

Yl \h R*t% l^S • C\KNf -ill ISMiTl TVN

death, or incapacity of an officer before the expiration of his or her term shall be filled by theBoard for the unexpired term; provided, however, that the Executive Committee shall bavepower to fill a vacancy in the office of Secretary to serve until it is filled by the Board.

Section 2.2. The Chairman shall preside at all meetings of the Board of Trustees and shallhave the usual powers of a presiding officer.

Section 2.3. The Vice-Chairman, in the absence or disability of the Chairman, shall performthe duties of the Chairman.

Section 2.4. The Secretary shall issue notices of meetings of the Board of Trustees, record theactions and minutes of the meetings of the Board and the Executive Committee, and conductthat part of the correspondence relating to the Board and the Committee and to his or herduties.

ARTICLE III

Executive Administration

Section 3.1. There shall be a President who shall be elected by, and hold office during thepleasure of, the Board of Trustees. The President shall be the chief executive officer of theInstitution and, subject to the directions and policies of the Board and the Standing Committeesof the Board, shall have general charge of all matters of administration and supervision of allarrangements for research and other work undertaken by the Institution or with its funds. He orshe shall prepare and submit to the Board and to the Standing Committees plans and suggestionsfor and reports of the work of the Institution. He or she shall have power to remove, appoint,and, within the scope of funds made available by the Board, provide for compensation ofsubordinate employees, and to fix the compensation of such employees within the limits of amaximum rate of compensation to be established from time to time by the Board. The Presidentshall be a member of each Standing Committee except the Audit Committee,

Section 3.2. The President shall be the legal custodian of the corporate seal and of allproperty of the Institution whose custody is not otherwise provided for. He or she shall sign andexecute on behalf of the Institution contracts and instruments necessary in authorized adminis-trative and research matters and affix the corporate seal thereto when necessary. He or she maysign and execute other contracts, deeds, and instruments on behalf of the institution (and affixthe corporate seal thereto when necessary) pursuant to general or special authority from theBoard of Trustees, the Executive Committee, or the Budget and Operations Committee. He orshe may, within the limits of his or her own authorization, delegate to other corporate officers orto the Directors of the Departments authority to sign and execute contracts, deeds, and instru-ments, to act as custodian of and affix the corporate seal, and to perform other administrativeduties. He or she shall be responsible for the expenditure and disbursement of all funds of theInstitution in accordance with the directions of the Board and of the Executive and the Budgetand Operations Committees and for the keeping of accurate accounts oi all receipts anddisbursements. He or she shall, with the assistance of the Directors of the Departments, submitto the Budget and Operations Committee annual operating and capital budgets to enable theCommittee to present its budget recommendations to the Board in accordance with Section 6.4.He or she shall prepare for timely presentation to the Trustees and for publication an annualreport on the activities of the Institution.

Section 3.3. The President shall attend all meetings of the Board of Trustees.

Section 3.4. The Institution shall have such other corporate officers as may be appointed bythe Board of Trustees or the Executive Committee, having such duties and powers as may bespecified by the Board or the Committee or by the President under authority from the Board orthe Committee.

Section 3.5. The President shall retire from office at the end of the fiscal year in which he orshe becomes sixty-five years of age, except as retirement may be deferred by the Board of Trusteesfor one or more periods of up to three years each. The other corporate officers shall retire as

C\K\\ .H N-T'7* in .\ • YEAR BOOK 95

officers, and the Directors of the Departments shall retire as Directors, at the end of the fiscalyear in which they become sixty-five years of age, except as otherwise required by law or asretirement may be deferred by the Board or the Executive Committee.

ARTICLE IV

Meetings and Voting

Section 4.1. Regular meetings of the Board of Trustees shall be held in the City of Washing-ton, in the District of Columbia, in May and December of each year on dates fixed by the Board,or in such other month or at such other place as may be designated by the Board, or if not sofixed or designated before the first day of the month, by the Chairman of the Board, or if he orshe is absent or is unable or refuses to act, by any Trustee with the written consent of themajority of the Trustees then holding office.

Section 4.2. Special meetings of the Board of Trustees may be called, and the date, time, andplace of meeting designated, by the Chairman of the Board, or by the Executive Committee, orby any Trustee with the written consent of the majority of the Trustees then holding office.Upon the written request of seven members of the Board, the Chairman shall call a specialmeeting.

Section 4-3. Notices of meetings of the Board of Trustees shall be given at least ten daysbefore the date thereof. Notice may be given to any Trustee personally, or by mail, telegram, orother means of record communication sent to the usual address of such Trustee. Notices ofadjourned meetings need not be given except when the adjournment is for ten days or more.

Section 4.4. The presence of a majority of the Trustees holding office shall constitute aquorum for the transaction of business at any meeting of the Board of Trustees. An act of themajority of the Trustees present at a meeting at which a quorum is present shall be the act of theBoard except as otherwise provided in these Bylaws. If, at a duly called and noticed meeting, lessthan a quorum is present, a majority of those present may adjourn the meeting from time to timeuntil a quorum is present. Trustees present at a duly called and noticed meeting at which aquorum is present may continue to do business until adjournment notwithstanding the with-drawal of enough Trustees to leave less than a quorum.

Section 4.5. The transactions of any meeting of the Board of Trustees, however called andnoticed, shall be as valid as though carried out at a meeting duly held if a quorum is present andif, either before or after the meeting, each of the Trustees not present in person signs a writtenwaiver of notice, or consent to the holding of such meeting, or approval of the minutes thereof.Ail such waivers, consents, and approvals shall be filed with the corporate records, and anofficer's certificate as to their receipt shall be made a part of the minutes of the meeting.

Section 4.6. Any action which, under law or these Bylaws, is authorized to be taken at ameeting of the Board of Trustees or any of the Standing Committees may be taken without ameeting if authorized in a document or documents in writing signed by all the Trustees, or all themembers of the Committee, as the case may be, then holding office and filed with the Secretarytogether with an officer's certificate as to their receipt.

Section 4.7. During any emergency peritxi the term "Trustees holding office" shall, forpurposes of this Article, mean the surviving members of the Board of Trustees who have notbeen rendered incapable of acting for any reason including difficulty of transportation to a placeof meeting or of communication with other surviving members of the Board.

ARTICLE V

Committees

Section 5.1. (a) There shall he eight Standing Committees of the Board of Trustees, denomi-nated Executive, Budget and Operations, Finance, Employee Affairs, Research, Development,

Yi \i

Audit, and Nominating.(b) Members of the Standing Committees (other than those identified in this Article

by the office they hold) shall be appointed by the Board of Trustees to serve for terms of threeyears, staggered so that at least one expires at each May meeting of the Board. They shall beeligible for reappointment. Except as otherwise provided in Sections 5.2(a), 5.3(a), and 5.9(a)with respect to the Executive, Budget and Operations, and Nominating Committees, the chair ofeach Standing Committee shall be appointed by the Board to serve until the next May meetingof the Board.

(c) A vacancy created before the expiration of a committee member's term by his orher resignation, death, incapacity, or ineligibility because of termination of service as Trusteeshall be filled by the Board of Trustees at its next May meeting and may be filled at an earliermeeting of the Board to serve for the remainder of the predecessor's term. A vacancy in theExecutive Committee and, upon request of the remaining members of any other StandingCommittee, a vacancy in such other Committee may be filled by the Executive Committee bytemporary appointment to serve until the next meeting of the Board.

(d) Committee members may participate in a meeting by means of conferencetelephone or similar communications equipment whereby all persons participating in themeeting can hear and speak to one another, and such participation shall constitute presence inperson at the meeting. Prompt notice of action taken at such a meeting shall be given to anymembers not present. Committee action may be taken by unanimous consent in writing asprovided in Section 4.6.

(e) Unless otherwise specified in this Article, the presence of a majority of themembers of a Standing Committee shall be necessary to constitute a quorum for the transactionof business.

(0 No Standing Committee shall have any of the powers of the Board of Trusteesrelating to proposing amendment of the Articles of Incorporation, amending the Bylaws, orelecting or removing a Trustee or the President.

(g) At each May and December meeting of the Board, each Standing Committee shallpresent to the Board a report, suitable for publication if the Board so desires, describing meetingsand actions of the Committee.

Section 5.2. (a) The Executive Committee shall consist of the Chairman, Vice-chairman, andSecretary of the Board of Trustees, the Chairman of the Finance Committee, and the President.The Chairman of the Board shall be the chair of the Committee.

(b) Subject to Section 5.1 (f), the Executive Committee may, when the Board ofTrustees is not in session and has not given specific directions, exercise the powers of the Boardincluding the power to authorize the purchase, sale, exchange, or transfer of real estate.

Section 5.3. (a) The Budget and Operations Committee shall consist of the Chairman, Vice-chairman, and Secretary of the Board, not less than five and not more than seven otherTrustees, and the President. The Chairman of the Board shall be the chair of the Committee.The presence of four members of the Committee shall be sufficient to constitute a quorum forthe transaction of business at any meeting.

<b) The Budget and Operations Committee shall have genera! control of the adminis-tration and affairs of the Institution and general supervision of all arrangements for administra-tion; research, and other matters undertaken or promoted by the Institution. Amendments ofemployee benefit plans other than those required by law or government regulation shall beapproved by the Committee. The Committee's responsibilities relating to financial matters shallinclude those described in Section 3.2 and Article VI.

(c) Regular meetings of the Budget and Operations Committee shall be held in Marchand September < >f each year.

Section 5,4. (a) The Finance Committee shall consist of the Chairman of the Board, not lessthan three and not more than six other Trustees, and the President. Hie presence of threemembers of the Committee shall be sufficient to constitute a quorum for the transaction ofbusiness M anv meeting.

(b) The Finance Committee shall have general charge of the Institutions investmentsand invented funds and shall care for and dispose of them subject to the directions c if the Board

of Trustees. It shall have power to authorize the purchase, sale, exchange, or transfer of securitiesand to delegate this power. It shall consider and recommend to the Board from time to time suchmeasures as in its opinion will promote the financial interests of the Institution and improve themanagement of investments under any retirement or other benefit plan.

(c) The Finance Committee shall be advisory to the Budget and Operations Commit-tee on spending policies.

(d) Regular meetings of the Finance Committee shall be held in March and Septemberof each year and immediately before the May and December meetings of the Board of Trustees.

Section 5.5. (a) The Employee Affairs Committee shall consist of the Chairman of the Board,the Chairman of the Finance Committee, not less than three and not more than five otherTrustees, and the President.

(b) The Employee Affairs Committee shall periodically review the compensation ofthe officers and other employees of the Institution and, if desired, make recommendations to theBudget and Operations Committee with respect thereto; review summaries of staff evaluationsincluding pertinent aspects of the reports of the departmental Visiting Committees; supervise theactivities of the administrator or administrators of retirement and other benefit plans for theInstitution's employees; receive reports from the administrator or administrators of the employeebenefit plans with respect to administration, benefit structure, operation, and funding; andconsider and recommend to the Budget and Operations Committee from time to time suchmeasures as in its opinion will improve the plans and their administration.

(c) Regular meetings of the Employee Affairs Committee shall be held immediatelybefore the May meetings of the Board of Trustees. The Committee shall hold additional meetingsas necessary or advisable for the performance of its duties.

Section 5.6. (a) The Research Committee shall consist of the Chairman of the Board, thePresident, the chairs of the departmental Visiting Committees, and not less than eight othermembers.

(b) The Research Committee shall review the research output of the Departments ofthe Institution, major needs for staff, facilities, and equipment, and the overall direction andfuture planning of the Institution's research and joint projects with other institutions. It shallreceive reports of the departmental Visiting Committees and periodic reports from the Directorsof the Departments.

(c) The Research Committee shall meet once a year, immediately before or after theDecember meeting of the Board of Trustees.

Section 5.7. (a) The Development Committee shall consist of not less than five and not morethan ten Trustees, and the President.

(b) The Development Committee shall have general responsibility for strategicplanning of fund-raising for the Annual Fund, the Endowment, and capital projects.

(c) Regular meetings of the Development Committee shall be held in conjunctionwith the semiannual meetings of the Board of Trustees in December and May. The Committeeshall hold additional meetings as necessary or advisable for the performance of its duties.

Section 5.8. (a) The Audit Committee shall consist of three trustees.(h) The Audit Committee shall cause the accounts of the Institution for each fiscal

year to he audited by public accountants and a report by the accountants to be submitted to theCommittee. The Committee shall present the report for the preceding fiscal year at the Maymeeting of the Board with such recommendations as the Committee may deem appropriate.

(c) Regular meetings of the Audit Committee shall he held in March of each year. TheCommittee shall hold additional meetings as necessary or advisable for the performance of itsduties.

Section 5.9, (a) The Nominating Ommittee shall consist of the Chairman of the Board, notless than three or more than five other Trustees, and the President. The chairman of the Boardshall appoint another member of the Committee as chair for a term expiring no Liter than theexpiration of his or her term as a member.

(M The duties of the Nominating Committee shall he to discover, recruit, and propose4

candidates for election to the Board of Trustees and as officers of the Board and for appointment

YE-KK FVvfc ^5 • V\¥\HHI I ' W m T;V N 157

as members and chairs of the Standing Committees. The Committee shall meet at least twice ayear and make reports to the Board at each of its regular meetings.

(c) At least sixty days before each May meeting of the Board of Trustees, the Nominat-ing Committee shall notify the Trustees by mail of the vacancies expected to be filled in themembership of the Board, the offices of the Board, and the Standing Committees. Each Trusteemay submit nominations for such vacancies in the Board. At least ten days before the Maymeeting, the Committee shall submit to the members of the Board by mail a list of the persons sonominated, with its recommendations for election of Trustees and officers of the Board andappointment of Committee members and chairs thereof. No other nominations shall be receivedby the Board at the May meeting except with the unanimous consent of the Trustees present.

(d) A Trustee may be elected at a meeting of the Board of Trustees other than the Maymeeting if the recommendation of the Nominating Committee with respect to his or hercandidacy was submitted to the members of the Board by mail at least ten days before the date ofthe meeting or the Trustees present at the meeting unanimously agree to waive this requirement.The solicitation of consents to election of a Trustee without a meeting of the Board pursuant toSection 4.6 shall include or be accompanied by the recommendation of the NominatingCommittee.

ARTICLE VI

Financial Administration

Section 6.1. No expenditure shall be authorized or made except in pursuance of a previousappropriation by the Board of Trustees, or as provided in Section 5.4 (b).

Section 6.2. The fiscal year of the Institution shall commence on the first day of July in eachyear. Financial statements for and as of the end of each fiscal year, together with the reportthereon of the firm of public accountants appointed by the Audit Committee, shall be sent tothe Trustees promptly after receipt of such report and shall be presented to the Board of Trusteesas provided in Section 5.8 (b).

Section 6.3. The President shall submit to the Board of Trustees at its December meeting afull statement of the finances and work of the Institution for the preceding fiscal year.

Section 6.4. The Budget and Operations Committee shall present to the Board at its Maymeeting a statement of estimated revenues and expenses for the current fiscal year and operatingand capital budgets for the succeeding fiscal year, including detailed estimates of revenues andexpenses.

Section 6.5. The Board of Trustees at its May meeting shall adopt operating and capitalbudgets and make general appropriations for the succeeding fiscal year; but nothing containedherein shall prevent the Board from making special appropriations at any meeting.

Section 6.6. The Budget and Operations Committee shall have general charge and control ofall appropriations made by the Board of Trustees. When the Board is not in session, the Commit"tee shall ha\e full authority to allocate appropriations made by the Board, to reallocate availablefunds, as needed, and to transfer balances.

Section 6.7. In accordance with Section 5.4 (b), subject to directions of the Board ofTrustees, securities of the Institution and funds invested and to be invested shall be placed in thecustody of such financial institution or institutions and under such safeguards as the FinanceCommittee may from time to time direct. Authority for investment of such securities and fundsmay be delegated to such managers or advisors as the Finance Committee may from time to timedesignate. Income of* the Institution available for expenditure shall be deposited in such financialinstitution or institutions AS may from time to time he designated by the Board. The Board mayauthorize the President to designate financial institutions to hold funds of the Institution.

Section 6.8 The property of the Institution is irrevocably dedicated to scientific, educational,and charitable purposes*, arid tn the event of dissolution its property shall be used for anddistributed nne or more of such purposes as specified by the Congress of the United States in the

Articles of Incorporation, Public Law No. 260, approved April 28, 1904, as the same may beamended from time to time.

ARTICLE VII

Indemnification; Transactions with interested persons

Section 7.1. The Institution shall, to the fullest extent required or permitted by applicablelaw, indemnify any person who is or was, or is the personal representative of a deceased personwho was, a Trustee, officer, employee, or agent of the Institution against—

(a) any liability asserted against him or her and incurred by him or her—(1) by reason of the fact that he or she (or his or her testator or intestate) is

serving or served in such capacity or at the request of the Institution as a director, trustee,partner, officer, employee, or agent of another corporation, partnership, joint venture, trust, orother enterprise, or as fiduciary of an employee benefit plan; or

(2) arising out of his or her (or his or her testator's or intestate's) service orstatus as such; and

(b) costs reasonably incurred by him or her in defending against such liability.Unless applicable law otherwise requires, indemnification shall be contingent upon a

determination, by majority vote of a quorum of the Board of Trustees consisting of disinterestedTrustees or, if such a quorum is not obtainable or a quorum of disinterested Trustees so directs, byindependent legal counsel in a written opinion, that indemnification is proper in the circum-stances because such Trustee, officer, employee, or agent has met the applicable standard ofconduct prescribed by District of Columbia law.

Section 7.2. No contract or transaction between the Institution and any of its Trustees orofficers, or between the Institution and any other corporation, partnership, association, or otherorganization in which any of its Trustees or officers is a director or officer or has a financialinterest, shall be void or voidable solely for that reason, or solely because the Trustee or officer ispresent at or participates in the meeting of the Board of Trustees or a committee thereof at whichthe contract or transaction is authorized, approved, or ratified or solely because his or her vote iscounted for such purpose, if—

(a) the material facts as to his or her relationship or interest and as to the contract ortransaction are disclosed or are known to the Board or the committee, and the Board or thecommittee in good faith authorizes the contract or transaction by the affirmative vote of amajority of the disinterested Trustees or committee members, even though they are less than aquorum; and

(b) the contract or transaction is fair to the Institution as of the time it is authorized,approved, or ratified by the Board or the committee.

ARTICLE VIII

Amendment of Bylaws

Section 8.1. These Bylaws may be amended (a) at any meeting of the Board of Trustees, by atwo-thirds vote of the incumbent members of the Board, or (b) by a two-thirds vote of themembers present at a meeting at which a quorum is present if notice of the proposed amendmenthas been given in accordance with Section 43 to each member of the Board at least twenty daysbefore the meeting and the amendment as adopted is substantially the same as proposed in thenotice, or (c) by unanimous written action pursuant to Section 4.6.

Section 8.2. Promptly after any amendment, notice thereof or the complete Bylaws asamended shall be delivered or mailed to each Trustee.

Photo, next page: The rotunda In the administration building, 1530 P Street, N.W.

V -

fc'

• Financial Profile •

Reader's note: all references to spending amounts and Endowment valuesare on a cash or cash~equivalent basis. The figures used in this profile donot include capitalization, depreciation, or other non-cash amounts.

Carnegie Institution of Washington relies upon its Endowment as theprincipal source of support for its activities. This reliance affirms thefundamental independence of the Institution's research and programs.

The Endowment, which was valued at $338 million as of June 30, 1996, is allo-cated across a range of assets that include fixed-income instruments (bonds),equities (stocks), arbitrage positions and distressed securities, hedge funds, privateequity, and real estate partnerships. The Institution does not manage these assetsitself. Rather, it utilizes external managers to do so, with the custody of theseassets, where applicable, being placed with a central custodian bank.

For the fiscal year ended at June 30, 1996, the percentage of total return (net ofmanagement fees) on Carnegie's total Endowment was 15.8%. The five-yearrunning, total average return on the Institution's Endowment was 13.6%. Thefollowing chart shows the allocation of the Institution's Endowment among theasset classes it employs as of June 30, 1996:

Asset AllocationActual Asset Allocation

Target Asset

AllocationActual AssetAllocation

Common Stock 40%Alternative Assets 35%Fixed Income 25%Cash 0%

44.5%29.5%23.4%2.6%

Cash2.6%

Fixed Income23.4%

Alt.Assets29.5%

Common Stock44.5%

Common Stock: small to large capitalization, marketable U.S. and International equity securities.

Alternative Assets: real estate, absolute return strategies, and non-marketable investments, such asprivate equity and special situations.

Fixed income: bond instruments, primarily U.S. domestic.

Cash: funds reserved for specific operating projects and funds awaiting reinvestment.

IK: • YEAR BOOK 95

Spending from the Endowment is budgeted with the goal of preserving theEndowment's long-term spending power. To do so, the Institution utilizes a budgetmethodology that:

•averages the total Endowment market values at the close of the three mostrecent fiscal years, and

•provides for spending a percentage of this three-year market value averageeach fiscal year.

Since the beginning of this decade, the percentage or "spending rate" used forbudgeting has been undergoing a planned reduction towards an average of 4.5% asan informal, non-mandatory goal For the 1996—1997 fiscal year, this percentage is5.66%. Concomitant with this reduction in the planned rate of spending has beensignificant growth in the size of the Endowment. This has resulted in progressivelyhigher spending levels. The following table shows the planned versus actualspending rates and the market value of the Endowment for the six-fiscal-yearperiod, beginning with 1990-199L

Endowment Market Values and Spending Rates

Fiscal Years ending June 30,

1991 1992 1993 1994 1995 1996

Market Valuein millions

Actual Spending Rate

Budgeted Spending Rate*

$225.9 $246.6 $270.4 $275.5 $304.5 $338.0

6.53% 5.49% 4.63% 4.51% 4.57% 4.48%

5.94% 6.16% 5.86% 5.81% 5.76% 5.71%

* applied to three-year average of total market value

Bugeted and Actual Spending Rates

Actual Spending Rate

— — . - . - Budgeted Spending Rate

1992 1993 19Q4 1995 1996

YEAR BOOK 95 • C u.v. j* I w > i'

Within the Endowment, there are a number of "Funds" that provide generalsupport or particular, targeted support for defined purposes. The largest of thesefunds, the Andrew Carnegie Fund, was established with a gift of $10 million fromAndrew Carnegie at the time the Institution was founded. This $10 million, alongwith an additional $12 million he gave during his lifetime, have now grown to afund valued at nearly $278 million. The following table shows the market value ofthe principal Funds within Carnegie's Endowment as of June 30, 1996.

Market value of the principal Funds within Carnegie's Endowment

Andrew Carnegie $277,959,578Capital Campaign 18,200,059Anonymous 7,756,513Astronomy Funds 6,012,189Mellon Matching 5,285,834Anonymous Matching 4,954,874Carnegie Futures 3,963,494Wood 3,537,945Golden 2,022,459Bowen 1,687,557Colburn 1,422,070McClintock Fund 1,001,771Special Instrumentation. 763,325Bush Bequest 636,682Moseley Astronomy 562,898Special Opportunities 503,745Roberts 289,541Lundmark 225,726Starr Fellowship 200,000Morgenroth 168,830Hollaender 157,734Bush 112,394Moseley 97,084Forbush 94,030Green 65,631Hale 60,321Harkavy 60,268Hearst Education fund 50,000Other 194,773

Total $338,047,325

• Yi u

Independent Auditors' Report

To the Auditing Committee of theCarnegie Institution of Washington:

We have audited the accompanying statement of financial position of theCarnegie Institution of Washington (the Institution) as of June 30, 1996, and therelated statements of activities and cash flows for the year then ended. Thesefinancial statements are the responsibility of the Institution's management. Ourresponsibility is to express an opinion on these financial statements based on ouraudit.

We conducted our audit in accordance with generally accepted auditingstandards. Those standards require that we plan and perform the audit to obtainreasonable assurance about whether the financial statements are free of materialmisstatement. An audit includes examining, on a test basis, evidence supportingthe amounts and disclosures in the financial statements. An audit also includesassessing the accounting principles used and significant estimates made by man-agement, as well as evaluating the overall financial statement presentation. Webelieve that our audit provides a reasonable basis for our opinion.

In our opinion, the financial statements referred to above present fairly, in allmaterial respects, the financial position of the Carnegie Institution of Washingtonas of June 30, 1996, and its changes in net assets and its cash flows for the yearthen ended, in conformity with generally accepted accounting principles.

Our audit was made for the purpose of forming an opinion on the basic finan-cial statements taken as a whole. The supplementary information included inSchedule 1 is presented for purposes of additional analysis and is not a requiredpart of the basic financial statements. Such information has been subjected to theauditing procedures applied in the audit of the basic financial statements and, inour opinion, is fairly presented in all material respects in relation to the basicfinancial statements taken as a whole.

As described in notes 1 and 7 to the financial statements, the Institutionadopted the provisions of Statements of Financial Accounting Standards No. 116,Accounting for Contributions Received and Contributions Made; No. 117, Financial

Statements of Not-far-Profit Organizations; No. 124* Accounting for Investments Held

by Not^for^Profit Organizations; and No. 106, Employers' Accounting for

Postretirement B<mefits Q^tker Than Pensions.

Washington, D.C.September 27, 1996

YJ \I> V* i i MS • i * \i,\; -

• Statement of Financial Position •June 30, 1996

AssetsCurrent assets:

Cash and cash equivalents $ 97,012Accrued investment income 867,735Pledges receivable (note 4) 2,622,740Accounts receivable and other assets 2,219,112Bond proceeds held by trustee (note 5) 15,032,558

Total current assets 20,839,157

Noncurrent assets:Investments (note 6) 362,041,971Construction in progress (note 2) 23,413,297Property and equipment, net (note 2) 38,282,583

Total noncurrent assets

Total assets

Liabilities and Net AssetsCurrent liabilities:

Accounts payable and accrued expensesDeferred revenuesBroker payable (note 6)

423,737,851

$444,577,008

$ 2,519,3591,247,330

23,752,995

Total current liabilities 27,519,684

Noncurrent liabilities:Bonds payable (note 5) 34,732,731Accrued postretirement benefits (note 7) 8,660,871

Total noncurrent liabilities 43,393,602

Total liabilities 70,913,286

Nee assets (note 3):Unrestricted:

Board designated:Invested in fixed assets, net 26,963,149Designated for managed investments 298,055,655

^ Undesignatcd 5,788,857

330,807,661

Temporarily restricted 10,511,799Permanently restricted ., 32,344,262

Total net assets 373,663,722

Commitments and contingencies (notes 8, 9, and 10)

Total liabilities and net assets. . $444,577,008

See auvmjMnvinj; nrte* tt) financial statements.

• Statement of Activities •Year ended June 30, 1996

Temporarily PermanentlyUnrestricted Restricted Restricted Total

Program and supporting services expenses:Terrestrial Magnetism $ 4,948,551Observatories 5,601,435Geophysical Laboratory 5,963,455Embryology 4,366,256Plant Biology 4,278,272Other Programs 972,927

Administrative and general expenses 2,962,056

4,948,5515,601,4355,963,4554,366,2564,278,272

972,9272,962,056

Total expenses 29,092,952 - 29,092,952

Revenues and support:Grants and contracts 10,143,786Contributions and gifts 212,159Net gain on disposals of property 3,480,506Other income 650,021

- 10,143,7863,354,873 1,244,592 4,811,624

3,480,506650,021

Net external revenue

Investment income (note 6)Net assets released from restrictions

Total revenues, gains, and othersupport

14,486,472

44,521,8602,056,057

61,064,389

3,354,873

2,208,597(2,056,057)

3,507,413

1,244,592

89,818-

1,334,410

19,085,937

46,820,275-

65,906,212

Increase in net assets before cumulativeeffect of the change in accountingfor postretirement benefits

Cumulative effect of the change inaccounting for postretirementbenefits (note 7)

31,971,437 3,507,413 1,334,410 36,813,260

(8,129,000) - (8,129,000)

Increase in net assets

Net assets at the beginning ofthe year, as restated (note 1)

23342,437 3,507,413 1,334,410 28,684,260

306,965,224 7,004,386 31,009,852 344,979,462

Net assets at the end of the year $330,807,661 10,511,799 32344,262 373,663,722

See accompanying notes to the financial statements

\ i '>} If8

• Statement of Cash Flows •Year ended June 30, 1996

Cash flows from operating activities:Increase in net assets $ 28,684,260Adjustments to reconcile increase in net assets to

net cash provided by operating activities:Depreciation 2,425,292Net gains on investments (37,297,991)Gain on sale of land and buildings (3,442,177)Amortization of bond issuance costs and discount 36,864(Increase) decrease in assets:

Receivables 358,122Accrued investment income (103,764)Bond proceeds held by trustee 4,614,925

Increase (decrease) in liabilities:Accounts payable and accrued expenses (1,318,884)Deferred revenues .. 995,281Brokerpayable 13,021,309Accrued postretirement benefits 8,660,871

Contributions and investment income restrictedfor long term investment (2,085,846)

Net cash provided by operating activities 14,548,262

Cash flows from investing activities:Acquisition of property and equipment (1,608,289)Proceeds from sale of land and buildings 3,780,673Construction of telescope, facilities, and equipment (8,408,479)Investments purchased (403,634,956)Investments sold or matured 393,114,394

Net cash used for investing activities (16,756,657)

Cash flows from financing activities:Proceeds from contributions and investment income restricted for:

Investment in endowment 921,635Investment in property and equipment 1,164,211

Net cash flows from financing activities 2,085,846

Net decrease in cash and cash equivalents (122,549)

Cash and cash equivalents at the beginning of the year ..» , 219,561

Cash and cash equivalents at the end of the year , $ 97,012

Supplementary cash flow information:Cash paid for interest ., $ 1,638,829

See accompanying notes to financial information.

• Notes to Financial Statements •June 30, 1996

(I) Organization and Summary ofSignificant Accounting Policies

Organization

The Carnegie Institution of Washington(the Institution) conducts advanced researchand training in the sciences. It carries out itsscientific work in five research centers. Theyare the Departments of Embryology, PlantBiology, and Terrestrial Magnetism, theGeophysical Laboratory, and the Observato-ries (astronomy). The Institution's externalincome is mainly from gifts and grants. It alsorelies heavily on income from invested gifts.

Basis of Accounting and Presentation

The financial statements are prepared onthe accrual basis of accounting.

The financial statements have beenprepared in accordance with Statement ofFinancial Accounting Standards (SFAS) No.117, Financial Statements of Not-for-ProfitOrganizations, which was adopted effectiveJuly 1, 1995 by the Institution. In accordancewith SFAS No. 117, expenses are separatelyreported for major programs and administra-tion. Revenues are classified according to theexistence or absence of donor-imposedrestrictions. Also, satisfaction of donor-imposed restrictions are reported as releases ofrestrictions in the statement of activities.

Investments

Effective July 1, 1995, the Institutionadopted the provisions of SFAS No. 124,Accounting for Investments Held by Not-far*Profit Organizations. In accordance with thisstandard, the Institution's debt and equityinvestments must be reported at their fairvalues. The Institution also reports invest-ments in partnerships at fair value as deter-mined and reported by the general partners.All changes in fair value are recognized in thestatement of activities. Adoption of this newstandard had no impact un net assets since theInstitution's previous policy was also to recordinvestments at fair value. The Institutionconsiders all highly liquid debt instruments

purchased with remaining maturities of 90days or less to be cash equivalents.

Income Taxes

The Institution is exempt from federalincome tax under Section 501 (c)(3) of theInternal Revenue Code (the Code). Accord-ingly, no provision for income taxes isreflected in the accompanying financialstatements. The Institution is also aneducational institution within the meaning ofSection 170(b)(l)(A)(ii) of the Code. TheInternal Revenue Service has classified theInstitution as other than a private foundation,as defined in Section 5O9(a) of the Code.

Fair Value of Financial Instruments

Financial instruments of the Institutioninclude cash equivalents, receivables,investments, bond proceeds held by trustee,accounts and broker payable, and bondspayable. The fair value of investments in debtand equity securities is based on quotedmarket prices. The fair value of investments inlimited partnerships is based on informationprovided by the general partners.

The fair value of Series A bonds payable isbased on quoted market prices. The fair valueof Series B bonds payable is estimated to bethe carrying value since these bonds bearadjustable market rates.

The fair values of cash equivalents,receivables, and accounts and broker payableapproximate their carrying values based ontheir short maturities.

Use of Estimates

The preparation of financial statements inconformity with generally accepted accountingprinciples requires management to makeestimates and assumptions that affect thereported amounts of assets and liabilities anddisclosure of contingent assets and liabilities atthe date of the financial statements. They alsoaffect the reported amounts of revenues andexpenses during the reporting period. Actualresults could differ from those estimates.

\K • C \K\h \:i 169

Property and Equipment

The Institution capitalizes expenditures forland, buildings and leasehold improvements,telescopes, scientific and administrativeequipment, and projects in progress. Routinereplacement, maintenance, and repairs arecharged to expense.

Depreciation is computed on a straight-linebasis over the following estimated useful lives:

Buildings and telescopes 50 yearsLeasehold improvements . . . lesser of 25 years

or the remainingterm of the lease

Scientific and administrativeequipment 5 years

Contributions

Effective July 1, 1995, the Institutionadopted the provisions of SFAS No, 116,Accounting for Contributions Received andContributions Made, which generally requiresthat unconditional contributions to theInstitution be recognized in the period pledgedby the donor. Prior to this new standard, theInstitution recognized unrestricted contribu-tions in the period they were received.Restricted contributions were deferred untilthe period in which expenses were incurred forthe intended purposes of these gifts. Theimpact of this new standard was an increaseand restatement of net assets as describedbelow.

In accordance with this standard, contribu-tions are classified based on the existence ofdonor-imposed restrictions. Contributions andnet assets are classified as follows:

Unrestricted—includes all contributionsreceived without donor-imposed restrictionson use or time.

Temporarily restricted—includes contribu-tions with donor-imposed restrictions as topurpi>&e of gift or time period expended.

Permanently restricted—generally includesendowment gifts in which donors stipulatedthat the corpus be invested in perpetuity. Onlythe investment income generated fromendowments may be spent.

Gifts of long-lived assets, such as buildingsor equipment, are considered unrestrictedwhen placed in service. The Institutionadopted the provisions of SFAS No. 116 furexpiration of restrictions on temporarily

restricted net assets on a retroactive basis.The following table summarizes the effects

of those accounting changes on net assets(previously referred to as fund balance) as ofthe beginning of the year.

Total

Balance, June 30,1995, as previously

reported $341,165,173Effect of accounting changes:

Pledges not previouslyrecorded 1,896,681

Gifts previouslydeferred 1,917,608

Balance, July 1,1995, as restated $344,979,462

These beginning net assets are classified asfollows:

Unrestricted $306,965,224Temporarily restricted 7,004,386Permanently restricted 31,009,852

$344,979,462

Contributed Services

The Institution recognizes the fair value ofcontributed services meeting certain criteria inthe financial statements as contributions.Generally, only needed professional servicesprovided by specialists are recognized.

Grants

The Institution records revenues on grantsfrom federal agencies only to the extent thatreimbursable expenses are incurred. Accord-ingly, funds received in excess of reimbursableexpenses are recorded as deferred revenue, andexpenses in excess of reimbursements arerecorded as accounts receivable. Reimburse-ment of indirect costs is based upon provi'sional rates which are subject to subsequentaudit by the Institution's federal cognizantagency.

(2) Pf(petty and Equipment

At June 30, 1996, property and equipmentplaced in service consisted of the following:

• V

Buildings and improvements . . $34,037,604Scientific equipment 13,593,569Telescopes 7,910,825Administrative equipment 2,163,650Land 787,896Art 34,067

$58,527,611Less accumulated depreciation.. (20,245,028)

$38,282,583

At June 30, 1996, construction in progressconsisted of the following:

Telescope $21,741,034Buildings 1,355,800Scientific equipment 316,463

$23,413,297

At June 30, 1996, approximately $31million of construction in progress and otherproperty, net of accumulated depreciation, waslocated in Las Campanas, Chile. During 1996,the Institution capitalized interest costs of$745,295 as construction in progress.

(3) Net Assets

At June 30, 1996, temporarily restrictednet assets were available to support thefollowing donor-restricted purposes:

Specific research programs $ 5,020,928Equipment acquisition and

construction 5,490,871

$10,511,799

At June 30, 1996, permanently restrictednet assets consisted of endowments, theincome from which is available to support thefollowing donor-restricted purposes:

Specific research programs . . . . $ 9,139,543Equipment acquisition

and construction 1,204,719General support

(Carnegie ertcfowment) , , , , 22.000,000

$32,344,262

During 19%, the Institution met donor-imposed requirements on certain gifts and

therefore released temporarily restricted netassets as follows:

Specific research programs $1,008,966Equipment acquisition

and construction 1,047,091

$2,056,057

(4) Pledges Receivable

Pledges receivable consisted of thefollowing at June 30, 1996 :

Due in year ending June 30,

1997 $1,600,5851998 743,8171999 175,8002000 27,6002001 15,0002002 and later 59,938

$2,622,740

(5) Bonds Payable

On November 1, 1993, the Institutionissued $17.5 million each of Series A andSeries B California Educational FacilitiesAuthority Revenue tax-exempt bonds. Bondproceeds are used to finance the Magellantelescope project and the renovation of thefacilities of the Observatories at Pasadena. Thebalances outstanding at June 30, 1996 onthese issues totaled $34,732,731, which is netof unamortized bond issue costs and bonddiscount. Bond proceeds held by the trusteeand unexpended at September 30, 1996totaled $15,032,558.

Series A bonds bear interest at 5.6 percentpayable in arrears semiannually on each April1 and October 1 and upon maturity onOctober 1, 2023. Series B bonds bear interestat variable money market rates in effect fromtime to time, up to a maximum of 12 percentover the applicable money market rate periodof between one and 270 days and have a statedmaturity of October 1, 2023. At the end ofeach money market rate period, Series Bbondholders are required to offer the bonds forrepurchase at the applicable money marketrate. If repurchased, the Series B Kinds wouldbe resold at the current applicable moneymarket rate and for a new rate period.

h - '

The Institution is not required to repay theSeries A and B bonds until the October 1,2023 maturity date, and the Institution hasthe intent and the ability to effect thepurchase and resale of the Series B bondsthrough a tender agent; therefore all bondspayable are classified as long term. Sinkingfund redemptions begin in 2019 in install-ments for both series. The fair value of SeriesA bonds payable at June 30, 1996 based onquoted market prices is estimated at$17,610,607. The fair value of Series B bondspayable at June 30, 1996 is estimated toapproximate carrying value as the mandatorytender dates on which the bonds are repricedare generally within three months of year end.

(6) Investments

At June 30, 1996, investments at fair valueconsisted of the following:

Time deposits $ 1,207,346Debt mutual funds 8,399,448Debt securities 109,478,430Equity securities 143,155,883Real estate partnerships 25,385,382Limited partnerships 74,415,482

$362,041,971

Investment income for the year ended June30, 1996 consisted of the following:

Interest and dividends .m $ 10,398,641Net realized gains 23,076,251Net unrealized gains 14,217,243Less investment

management expenses .. (871,860)

$46,820,275

The Institution purchased and sold certaininvestment securities on dates prior to June30, 1996. These trades will be settledsubsequent to June 30, 1996 and are reflectedin the investment balances reported at yearend. The net obligation for these unsettledtrades is reported as broker payable in theaccompanying statement of financial position.

The Institution enters into futurescontracts to manage portfolio positions andhedge transactions. Risks relating to futurescontracts arise from the movements insecurities values and interest rates.

Realized |*ains and losses based on changes

in market values of open futures contractshave been fully recognized. The contracts aresettled daily for changes in their fair value.Accordingly, the fair value of the contracts atJune 30, 1996, is zero. At June 30, 1996,investments with a fair value of approximately$112,000 were being held by an intermediaryas ongoing collateral against the Institution'sobligations under futures contracts. The totalnotional value of these contracts at year endwas approximately $4,500,000.

(7) Employee Benefit Plans

Retirement Plan

The Institution has a noncontributory,defined contribution, money-purchaseretirement plan in which all United Statespersonnel are eligible to participate. After oneyear's participation, an individual's benefits arefully vested. The Plan has been fundedthrough individually owned annuities issuedby Teachers' Insurance and Annuity Associa-tion (TIAA) and College Retirement EquitiesFund (CREF). There are no unfunded pastservice costs. Total contributions made by theInstitution totaled approximately $1,737,000in 1996.

Postretirement Benefits Plan

The Institution provides postretirementmedical benefits to all employees who retireafter age 55 and have at least ten years ofservice. Prior to 1996, the cost of postretire-ment benefits was charged to expense only ona cash basis (pay-as-you-go). Cash paymentsmade by the Institution for these benefitstotaled approximately $398,000 in 1996.

Effective July 1, 1995, the Institutionadopted SFAS No. 106, Employers' Accountingfor Postretirement Benefits Other Than Pensions,and changed its method of accounting forpostretirement benefits from a cash basis to anaccrual basis. This accounting change resultedin a one-time, noncash expense in 1996 ofapproximately $8,129,000 for the transitionobligation. The transition obligation repre-sents the fully recognized actuarially deter-mined estimate of the Institution's obligationfor postretirement benefits as of July 1, 1995.The expense for postretirement benefits in1996 under the provisions of SFAS 106 wasapproximately $930,000, which is an increaseof $532,000 over what the cash expense wouldhave been, and was allocated among programand supporting services expenses.

172 C-\h\F*>lF K-1IT1 K< >\ • YlAR 95

The following items are the components ofthe net postretirement benefit cost for 1996:

Service cost—benefitsearned during the year $335,000

Interest cost on projectedbenefit obligation 595,000

$930,000

The following table sets forth the fundedstatus of the postretirement medical benefitsplan as of its June 30, 1996 actuarial valuationdate for 1996:

Actuarial present value of the accumulatedpostretirement benefit obligation for:

Inactive participants $4,541,000Fully eligible active

participants 1,828,000Other active participants . . . . 2,025,000

Accumulated postretirementbenefit obligation for servicesrendered to date 8,394,000

Unrecognized net gain 266,871

Accrued postretirementbenefit cost $8,660,871

The present value of the transitionobligation as of July 1, 1995 was determinedusing an assumed health care cost trend rate of10 percent and an assumed discount rate of 7.5percent. The present value of the benefitobligation as of June 30, 1996 was determinedusing an assumed heath care cost trend rate of10 percent and an assumed discount rate of 7.5percent. The Institution's policy is to fundpostretirement benefits as claims and adminis*trative fees are paid.

For measurement purposes, a 10 percentannual rate of increase in the per capita cost ofcovered health care benefits was assumed for1996; the rate was assumed to decreasegradually to 5.5 percent in 15 years andremain at that level thereafter. The healthcare cost trend rate assumption has a signifi-cant effect on the amounts reported. Anincrease of 1.0 percent in the health care costtrend rate used would have resulted in a$1,192,000 increase in the present value ofthe accumulated benefit obligation and a$191,000 increase in the aggregate of serviceand interest ciwt components of net peruxJiepostretirement benefit cost.

(8) Federal Grants and Contracts

Cost charged to the federal governmentunder cost-reimbursement grants andcontracts are subject to government audit.Therefore, all such costs are subject toadjustment. Management believes thatadjustments, if any, would not have asignificant effect on the financial statements.

(9) Commitments

In 1992, the Institution entered into acollaborative agreement with the University ofArizona for the construction and operation ofa large^aperture telescope (Magellan project)and its installation and operation in Chile.The agreement requires the University ofArizona to deliver a primary mirror to be usedin the Magellan project for $635 million,subject to adjustment. The telescope iscurrently under construction. The Institutionhas agreed to share use of the Magellantelescope for a period lasting until expirationof the agreement in 2022. Viewing time onthe telescope and annual operating costs willbe shared by each of the parties in amounts tobe determined based on amounts ultimatelycontributed by each party for construction.

During 1996, the Institution also enteredinto memoranda of understanding with threeother universities to jointly construct andoperate another telescope in Chile. Theseagreements will provide for the creation of aconsortium to construct and manage thetelescope. Advance payments received fromthese universities totaling approximately$518,000 have been classified as deferredrevenue (liability) in the accompanyingstatement of financial position.

(10) Lease Arrangements

As landlord, the Institution leases land anda laboratory, under noncancelable agreementsto certain tenants. Future rents to be receivedfor the leased land is $120,000 annuallyexpiring in fiscal year 2001.

The lease for the laboratory is for anindefinite term. Rents to be received underthat agreement are approximately $179,000annually, adjusted for CP1 increases.

Yl \¥ Fk \ "K 95 • C \KNEi .if.

• Schedule of Expenses •Schedule 1

Year ended June 30, 1996

Federaland

Personnel costs:SalariesFringe benefits and payroll taxes

Total personnel costs

Fellowship grants and awards

Equipment

CarnegieFunds

$ 9,415,7323,532,528

12,948,260

758,565

884,230

PrivateGrants

3,114,712820,783

3,935,495

1,045,956

1,820,383

TotalExpenses

12,530,4444,353,311

16,883,755

1,804,521

2,704,613

General expenses:Educational and research supplies 615,634Building maintenance and operation 1,387,370Travel and meetings 518,233Publications 24,570Shop 65,521Telephone 174,765Books and subscriptions 211,156Administrative and general 1,563,973Fundraising expense 112,522

1,153,041896,318558,10667,40816,984

2176,592

404,981_

1,768,6752,283,6881,076,339

91,97882,505

174,982217,748

1,968,954112,522

Total general expenses

Indirect costs-grants

Indirect costs capitalizedon scientific construction projects

Total expenses

4,673,744

(2,693,547)

(77,328)

. . . . . . $16,493,924

3,103,647

2,693,547

12,599,028

7,777,391

_

(77,328)

29,092,952

174 • Yi \>

• Index of Names •Abbott, Jennifer, 89Abelson, Philip H., v, vi, 14, 151, 152Adam, Luc, 113Aguilar, Carmen, 140Ahnn, Joohong, 89Aldrich, L. Thomas, 65Alexander, Conei, 49, 65

Special essay, 57—64Andalman, Aaron, 22Apt, Kirk, 113

Babcock, Horace, 37Bauer, Donna, 89Becker, Harry J., 65Bell, David, 140Bell, Peter, 140Bellini, Michel, 89Benton, Laurie, 65Berkelman, Thomas, 113Bernstein, Rebecca, 37Berry, Deborah, 89Berry, Joseph, 111, 113Bertka, Constance, 140Bhaya, Devaki, 113Bjarnason, Ingi, 65, 66Bjorkman, Olle, 96-97, 113

Special essay, 99-105Blank, Jennifer, 140Boss, Alan, 48, 65Bowers, Ray, 11, 149Boyd, F.R., 11,140Brandon, Alan D.} 65Briggs, Winslow R., 6, 7, 11, 113Broun, Pierre, 113Brown, Donald D., 8, 12, 89, 150Brown, Louis, 65Buell, Robin, 113Burner, Harold, 65

Calvi, Brian, 89Carlson, Richard W., 65Chambers, John E., 65Cifuentes, Ine"s, 149Cody, George, 119, 140

Special essay, 128-135Cohen, Ronald, 6, 140Cohen-Fix, Orna, 89Coleman, William T., Jr., v, 151, 152Collelo, Gregory, 113Conrad, Pamela, 12, 140Craig, Patricia, 11, 149Crawford, John E, v, 151,152Cutler, Sean, 113

Daicanton, Jutianne, 22, 37

Special essay, 31—36David, Edward E., Jr., v, viDavidson, Paula, 140Davies, John, 113de Cuevas, Maggie, 89Dej, Kim, 89Dement, Elise, 113Diebold, John, v, 151, 152Downs, Robert T, 140Dressier, Alan, 7, 12, 13, 37Dunn, Robert A., 65Dymecki, Susan, 74, 89

Special essay, 77—81

Ebert, James D., v, vi, 14, 151, 152Ernst, W. Gary, v, 151, 152

Faber, Sandra M., v, 14, 151, 152Falcone, Deane, 113Fan, Chen-Ming, 13, 75, 89Farber, Steve, 89Farquhar, James, 140Fei, Yingwei, 11, 140Ferguson, Bruce W., v, 151, 152Ferguson, Mack, 10Field, Christopher, 6, 7, 97, 113, 150

Special essay, 106-112Finger, Larry, 13, 140Fire, Andrew Z., 89Fisher, Shannon, 89Fogel, Marilyn L., 6, 119, 140

Special essay, 121-127Foster, Prudence, 65Frantz, John D., 140Freedman, Wendy, 7, 37Friedlingstein, Pierre, 113Frost, Daniel J., 140Frydman, Horacio, 89Fu,Wet, 113Furlow, David, 89

Gail, Joseph G., 6, 12,89Galiart, Carme, 37Garda, Gianna, 65Garvey, Susanne, 149, 151Geliert, Michael, i', 151,152Giavaiisco, Mauro, 37Gillmor, Adam, 113Goelet, Robert G.,v, 152Golden, William T., i\ 14, 151, 152Goncharov, Alexander, 140Goodfriend, Glenn, 140Graham, John A., 48, 65

Special essay, 50-56Granger, Claire, 113

Vi v>

Greenewalt, David, v, 151, 152Grivet, Cyril, 10Grossman, Arthur, 6, 96, 113

Special essay, 99-105Guacci, Vincent, 89

Halpern, Marnie, 89Hammouda, Tahar, 12, 140Hare, P. Edgar, 140Harfe, Brian, 89Haskins, Caryl P., v, vi, 151Hauri, Erik, 2, 8, 65Hazen, Robert, 13, 140Hearst, William R., Ill, v, 152Heckert, Richard E., v, 152Helmer, Elizabeth, 89Hemley, Russell, 8, 13, 140Herold, Lori K., 65Hewlett, William R., v, 14Hill, Bob, 37Hoang, Nguyen, 65Hoffman, Neil R, 113Hoppe, Katherine, 65Hsieh, Jenny, 89Hu,Jingzhu, 140Huala, Eva, 113Huang, Haochu, 89Huang, Shaosung, 65Humayun, Munir, 65Hungate, Bruce, 110

Inamori, Kazuo, v, 152Inbar, Iris, 140Irvine, X Neil, 140Ita,JoelJ., 140

James, Charles, 149James, David E., 6, 65Joel, Geeske, 113Johnson, Beverly, 119, 140

Special essay, 121-127Johnson, Catherine L, 65

Kanamori, Akira, 89Kehoe, David M., 113Kelly, William, 89Keyes, Linda, 89Kluge, Mark, 140Knesek, Patricia, 11, 37Kokis, Julie, 140Koshland, Douglas, 89Kostas, Steve, 89Kress, Victor, 140Kristian, Jerome, 10, 37Krzeminski, Wojciech, 37Kunkel, William, 37Kurina, Lianne, 113

Landy, Stephen, 37Lassiter, John C, 65

Laubach, Gerald D., v, 151Lazor, Peter, 140Lee, Catherine, 89Li, Ming, 140Li, Wei, 140Lilly, Mary, 89Linde, Alan X, 65Lindley, Catharina, 113Linton, Jennifer, 140Lithgow-Bertelloni, Carolina, 65Liu, Lanbo, 65Lively, John JM 149,151Lu, Ren, 140Lubin, Lori, 37Lukowitz, Wolfgang, 113Lund, Chris, 108, 113

Macfarlane, Allison, 14Macomber, John D., v, 151, 152Majewski, Steve, 37Malmstrom, Carolyn, 111, 113Mao, Ho-kwang, 8, 12, 13, 140Mafdones, Diego, 37Margolis, Jonathan, 89Marsh-Armstrong, Nick, 89Martin, William McChesney, Jr., vMazin, Igor, 140McCarthy, Patrick, 22, 37

Special essay, 23-30McGaugh, Stacy S., 33, 65McGovern, Patrick, 65Me William, Andrew, 37Megee, Paul, 89Meluh, Pamela, 89Mendez, Liz, 89Meserve, Richard A., v, 151,152Miller, Bryan WM 65Miller, Valarie, 89Montgomery, Mary, 89Mortl, Amanda, 14Mulchaey, John, 37Murphy, David, 37Myhill, Elizabeth, 65Mysen, Bj0rn O., 140

Namiki, Noriyuki, 65NikoiofT, Michelle, 113Nishizawa, Yoko, 113Nittler, Larry, 64Niyogi, Krishna, 96, 113

Special essay, 99-105Norton, Garrison, vi, 151

Oemler, Augustus, Jr., 8, 37, 151Director's introduction, 21—22

Ogas, Joseph, 113Olney, Margaret, 113Osborn, Julie, 113

Pepling, Melissa, 89

176 CARNEGIE INSTITUTION • YEAR BOOK 95

Perkins, Richard S., vPersson, Eric, 37Phelps, Randy, 37Pilgrim, Marsha, 113Paler, Jasha, 65Polsenherg, Johanna, 113Preece, Shari, 65Press, Frank, v, 14, 65, 140, 151, 152Preston, George, 37Prewitt, Charles T., 8, 140, 151

Director's introduction, 119-120

Quails, William, 10

Rabinowitz, David, 65Randerson, Jim, 113Rauch, Michael, 37Reiser, Steven, 113Rhee, Seung, 113Rinehart, Carl, 10R0rth, Pernille, 74, 89

Special essay, 82-88Roth, Miguel, 37Rubin, Vera, 7, 12, 13,65Rubinstein, Amy, 89Ruimy, Anne, 113Rumble, Douglas, 111, 119, 140

Special essay, 137-139Rumpker, Georg, 65Rush, Brian, 29, 37Rutter, William J.,v, 14,152

Sacks, I. Selwyn, 65Saghi-Szabd, Gotthard, 140Sanchez, Alejandro, 89Sandage, Allan, 37Schindelbeck, Thomas AM 140Schlappi, Michael, 89Schneider, Lynne, 89Schulze, Waltraud, 113Schwartzman, Rob, 89Schwarz, Rakefet, 113Schweizer, Francois, 65Seamans, Robert C, Jr., v, 14Searle, Leonard, 8, 11, 37Seydoux, Geraldine, 89Shectman, Stephen, 37Shen, Guoyin, 140Shen, Yang, 65Shirey, Steven B., 6, 65Shu, Jinfii, 140Silver, Paul G., 8, 65Simom, Fiorella, 140Simons, Mark, 65Singer, Maxtne, B, 149, 151

President s commentary, 1-9publications of, 150

Sivarumaknshnan, Anand, 37Small, Ian, 37Smith, Bessie, 10

Smith, David, 45Soiheim, Larry, 65, 140Solomon, Sean C, 6, 7, 8, 12, 13, 65, 151

Director's introduction, 47-49Somayazulu, Madduri, 140Somerville, Christopher, 6, 7, 9, 12, 113

Director's introduction, 95-97Somerville, Shauna, 113Spradling, Allan, 8, 12, 13, 84, 89, 151

Director's introduction, 73-75Stanton, Frank, vStill, Chris, 113Stochaj, Wayne, 113Strunnikov, Alexander, 89Struzhkin, Viktor, 140Swensen, David E, v, 151, 152

Teece, Mark, 140Tera, Fouad, 65Teter, David M., 140Thayer, Susan, 113Thio, Hong Kie, 65Thompson, Catherine, 89Thompson, Ian, 37Torreson, Oscar, 10Townes, Charles H, v, 14, 151Tunell, George, Jr., 10Turner, William I. M., Jr., v, 152

Urban, Thomas NL, v, 151

VanDecar, John, 65, 140van der Lee, Suzan, 65van Wijk, Klaas, 113Vasquez, Susan, 149, 151Virgo, David, 140

Walter, Michael, 140Weinberg, Sidney J., Jr., v, 151, 152Wetherili, George W, 6, 48, 65Weymann, Ray, 37Wiilick, Jeffrey, 37Wilsbach, Kathleen, 89Wilson, Iain, 113Wolfe, Cecily, 65, 140Woodworth, Felice, 10Wu, Chung-Hsiun, 89Wu, Tammy, 13Wycoff, Dennis, 113

Xie, Ting, 89

Yang, Hexiong, 140Yoder, Hattcn S., Jr., 140

Zabludoff, Ann, 37Zha, Chang-Shcng, 140Zhang, James, 113Zhang, Ping, 89Zheng, Yixian, 11