Senior Research Projects 2011 - 2012

Neuron Modeling - Nassir Abou Ziki '12

Neuron modeling has been gaining a lot of attention because of the increasing interest in interfacing electronic neurons with living tissue. Moreover, creating accurate neuron models helps students understand the dynamics of the neuron better and also gives the opportunity to study a wide range of neural networks. However, since the neuron dynamics are nonlinear this makes it hard to create and implement those models.

The aim of this project is split into two phases; the first is to build the model proposed by Sitt et al. and recreate the same results they got in their experiment. The electric model proposed by Sitt et al. models the opening and closing dynamics of the channels present in the membrane, in addition to the behavior of the synapse (inhibitory as well as excitatory). The neuron circuit presented by this model is fairly complicated, thus the second goal is to carefully characterize the behavior of the neuron circuit as a function of its various inputs.

For more information, contact Dr. Catherine Jahncke

Constructing a Raman Spectrometer - Jameson Cook '12

Raman spectroscopy is a method of analyzing a substance using a strong uniform light source, such as a laser, and a spectrometer to determine what the sample is made of. It relies on the inelastic scattering of light, where a sample absorbs the incident photons and emits them with a slightly shifted wavelength corresponding to the energy lost or gained in the sample, also known as Raman scattering.

Raman spectroscopy came soon after as a method of analyzing chemical compositions of a substance based on the uniquely scattered light. Different compounds or molecules emit these uniquely shifted photons depending on the chemical bonds between each atom. This provides us with a fingerprint for a sample that is compared to known spectra. Based on the unique peaks corresponding to certain chemical bonds, the sample can be identified. 

My project uses a Horiba Triax 550 spectrometer fitted with a SBIG ST-7 CCD camera and a 532 nm diode laser, as well as a collection of mirrors, lenses, and filters required to perform Raman spectroscopy.  We chose to measure the Raman spectra of Silicon due to the availability of a pure crystal sample as well as the spectrum of Naphthalene for the same reasons.

For more information, contact Dr. Catherine Jahncke

Examining the Effects of Hesperetin on B16 Melanoma Cells Using Raman Spectroscopy - Dylan Cutler '12

Recent studies have suggested that the antioxidant properties of citrus flavonoids, found in fruits such as grapefruit and oranges, inhibit the growth of cancerous cells. However, few studies have been conducted on the naturally occurring flavonoid hesperetin (3’, 5, 7-trihydroxy-4-methoxyflavanone). The purpose of this study was to determine whether hesperetin has a melanogenic effect on melanoma cells, and if this can be detected using Raman spectroscopy. B16 mouse melanoma cells were treated with hesperetin and imaged using a Raman spectrometer. We hypothesized that a comparison between the Raman spectra of treated melanoma cells and untreated melanoma cells would illustrate an increase in tyrosinase activity in the treated B16 mouse melanoma cells. Therefore, we expected that this increase in tyrosinase would be observed as a decrease in Raman signal of tyrosine. Our Raman spectra results demonstrated that hesperetin decreased the amount of tyrosine protein present in the melanoma cells indicating that tyrosinase enzymatic activity was increased. Additionally, microscopic images of melanoma cells suggested that hesperetin inhibited transcription and cell replication.

For more information, contact Dr. Catherine Jahncke

HI Depletion in Zw 1400+0949 - Heather Cutler '12

Using HI data from the ALFALFA survey and optical data from the Sloan Digital Sky Survey (SDSS), we have identified 111 galaxies that appear as a group on the sky and in distance from us as members of the poor cluster Zw 1400+0949. In a gravitationally bound cluster, interactions between galaxies and the cluster atmosphere strips HI gas from the galaxies, making them HI deficient compared to isolated galaxies of the same type. To determine whether or not Zw 1400+0949 is a gravitationally bound cluster we examine the deficiency of HI in these galaxies by comparing their observed HI content with the expected HI content calculated using methods given by Solanes et al (1996) and Toribio et al (2011). There is available HI data for 64 of the galaxies we selected. We find that the galaxies studied do not show HI deficiency according to the Toribio method and 13 of the galaxies were HI deficient according to the Solanes method. Based on these mixed results, HI deficiency does not provide conclusive evidence for Zw 1400+0949 being a gravitationally bound cluster.

For more information, contact Dr. Aileen O'Donoghue

Recreating Booming Sand: Collective Vibrations of Marbles in a Granular Flow - Tim Moore '12

Specific regions of the world have sand that when avalanched down a dune face will emit a low booming sound. It has been hypothesized that for sand to “boom” it must be very dry and well-sorted, with round grains of similar size and composition. A collection of marbles cascading down an incline has these characteristics. The purpose of the experiment was to see if marbles can exhibit the booming characteristic and if so whether the emitted frequency matched the frequency predicted by Bagnold. The dune was replaced in the experiment with a trough, having one Plexiglas side, which could be raised to varying angles and was lined with marbles glued on the bottom. Approximately 22,000 marbles were released down the trough. We recorded the audio signal of the flow at various angles and a high-speed video capture of the flow as seen from the side. The audio signal was analyzed with the discrete Fourier transform to identify resonant frequencies. The essential parameter in the Bagnold equation is the marble density within the flow, which was determined using the video capture. Analysis of the experimental spectra show the background frequencies of the experimental setup are at a higher decibel level than any possible booming frequencies that may have been recorded.

For more information, contact Dr. Brian Watson