8/4/2019 LeifHague.brianna.I STEM Poster

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Leif Hague and Brianna Hajek, under the supervision of Prof. Taher Saif, in collaboration with Emerson De SouzaUniversity Laboratory High School and the Department of Mechanical Science and Engineering, College of Engineering, University of Illinois at Urbana-Champaign

Quantifying Mechanical Synchronization of Metronomes

Acknowledgments

Conclusions

During our time in Prof. Saifs lab, we gainedexperience which would have been difficult to acquirein a different setting. Because of the amount of timerequired to carry out this experiment, it w ould beimpossible to complete it at school within areasonable time frame. We were able to learn what itis like to work with others in a research lab anddevelop an experiment. The metronome experimentwas performed largely from scratch, withoutbackground research or specific instructions. ThoughDr. De Souza was available to help us if we hadtrouble and guide us in the right direction, we workedfor many hours independently, which does not happenoften in a school setting. Overall, this was a goodexperience to give us an idea of what it is like to workin a research lab and prepare us for future scientific

research in similar settings.

Aim

Though the synchronization of metronomes is knownto be mechanical, it is unclear whether the process ofsynchronization of cardiac cells is mechanical orelectrochemical. The purpose of this experiment is todetermine this by comparing the synchronization ofmetronomes and cardiac cells.

The synchronization of metronomes is quantified bytracking the movement of the pendulums using aprogram in MATLAB. Our job was to find theconditions under which the program could track themovement.

Introduction

Through the University Laboratory High School I-STEM Summer Research Experience, we worked for

three weeks in Prof. Taher Saifs laboratory underpostdoctoral scientist Emerson De Souza. Dr. DeSouza is currently researching the behavior of cardiaccells.

When removed from the heart and distributed in aplastic container, cardiac cells continue to pulse. Thecells pulse independently until enough connectivetissue (fibroblasts) grows back to join the cardiaccells. At this point, the pulsing synchronizes. Dr. DeSouza is interested in determining the cause of thissynchronization.

Similarly, metronomes set at the same or similarfrequencies synchronize when placed on a metalplate resting on two soda cans (see figure 1). This isa purely mechanical phenomenon.

We assisted Dr. De Souza in running experimentsconcerning the synchronization of metronomes andcardiac cells.

Method (cont.)

There are certain conditions under which the programcan track the pendulums. We used ten second videos

to test various situations in order to find the correctsettings for the full experiment.

We varied:Frequency of metronomesResolution of videosNumber of pixels the MATLAB program tracked(correlation size)

The frequency and resolution affect the number ofpixels that the pendulum moves per frame of video. Ifthis number is too high, the program has difficultytracking it. Increasing the number of pixels trackedallows the program to track points that move at fasterrates.

The metronomes are slightly inaccurate as well,which will affect the experiment.To account for this,we found the actual frequencies of each metronomeby analyzing the pattern of its movement.

Results

For frequencies of 50, 100, and 200 beats per minute(BPM), the program was able to track the pendulumsat video resolutions of 256x256, 512x256, and1024x256 pixels. All of these worked with acorrelation size of 5x5 pixels. We found 1024x256pixels to be the best frame size because thependulums of up to three metronomes can be seenwith little excess space.

We calculated the expected frequencies, in Hz, of themetronomes at 104, 152, and 108 BPM. Wecompared these with the observed frequencies todetermine the inaccuracy of each metronome.

Remainder of Experiment

Dr. De Souza will use the MATLAB script to track themovement of cardiac cells and produce a graph of thesynchronization of their movements. This graph willbe compared to the graph of metronomesynchronization, and the degree of similarity will beused to determine the reason for cardiac cellsynchronization. If the graphs are similar or identical,the synchronization of cardiac cells, like that ofmetronomes, can be considered a purely mechanicalphenomenon. If they are different, then thesynchronization of cardiac cells likely occurs throughelectrochemical means.

Figure 6. This graph, the fourier transform ofthe graph in fig. 4,shows the average frequency and amplitude of that graph.

Figure 5. The horizontal

movement of the

pendulum of a

metronome resting on

soda cans, which moveas the pendulum swings,

can be represented as a

wave within a wave.

Figure 2. White dots and

black backgroundattached to pendulum.

Figure 3. High speed camera with metronome on moving platform.

Figure 1. Metronom es

on 100g metal sheet

resting on two soda cans.

Figure 4. The horizontal

movement of a

metronome pendulum

over time can be

represented as a sine

wave.

Method

In order to track the movement of the pendulums, wetook high speed videos of the metronomes in motionand extracted the frames. We had attached blackstrips with white dots to the pendulums so that theprogram in MATLAB could track the movement ofwhite pixels against a black background (see figure

2).

Metronome Deviation

A 2.49-3.67%

B 1.84-3.07%

C 0.76-1.84%