Tag: Poster 13

Sound-evoked Response Properties of Parvalbumin-expressing Interneurons in Mouse Auditory Cortex: Implications for Inhibitory Gain Control

Presenter: Alexandra K. Hartman

Mentor: Michael S. Wehr

AM Poster Presentation

Poster 13

In auditory cortex, sounds are encoded by neurons ‘tuned’ to specific acoustic features. The sound-evoked response properties of these cells are powerfully shaped by inhibitory synaptic input. All cortical inhibition is provided by local interneurons, which comprise <20% of the cortical population. In contrast to excitatory neurons, inhibitory interneurons can be separated into numerous morphologically and neurochemically distinct subclasses. Little is known about the sound-evoked response properties of different types of inhibitory interneurons, as conventional in vivo recording techniques provide limited information about the identity of recorded neu- rons. Here, we identified neurons as members of the Parvalbumin (PV) expressing inhibitory subclass through light-activation of an optogenetic ‘tag’ (channelrhodospin-2), and measured their receptive field properties. In mouse visual cortex, PV neurons are found to be broadly tuned for orientation and respond more gradually to increasing stimulus intensity than principal neurons. In contrast, our preliminary results indicate that auditory PV neurons are well-tuned for sound frequency and have significantly steeper intensity- response functions than principal neurons. Recent studies have shown that PV interneurons in both cortices function to modulate the gain of principle cells without affecting their tuning. The differences we observe in their response properties may allow them to scale tuned responses in auditory and visual cortex, in identical ways.

Domain-Specific Heaven and Hell: A Matching Theory Method for Generating Permutations of a Popular Joke

Presenter : Noah Cooper

Mentor : Michael Hennessy

Major : Computer & Information Science

Poster 13

Heaven is where the police are English, the cooks are French, the mechanics are German, the lovers are Italian, and it’s all organized by the Swiss. Hell is where the police are German, the cooks are English, the mechanics are French, the lovers are Swiss, and it’s all organized by the Italians.” So goes the well-known joke reflecting some positive and negative stereotypes of European nations. Every intellectual community, too, has its famous methods, theories, and authors — each known for its merits as well as its shortcomings. So it would seem fertile ground for parodies of the European Heaven & Hell joke. But it turns out this joke has a peculiar structure that re- sists parody. My work analyzes that structure, demonstrating why an ad-hoc attempt at parody is prone to fail. It proposes an alternative algorithmic approach to generating parodies based on matching theory, a subfield of graph theory in finite mathematics. In so doing, I hope it makes some small contribution to the body of knowledge on computer-generated humor and the semantics of humor.“noise” produced by background turbulence may inhibit the capacity of the ctenophore to detect and respond to fluid motions produced by its prey.

Air paths in Lewis

Presenter: Petro El Hage

Co-Presenters: Lenore Wan, Caitlin Vanhauer

Mentor: Alison Kwok

Poster: 13

Major: Architecture 

We studied how the air handling system functions in Lewis Integrative Science Building (LISB) atrium and whether or not the relief air vents are utilised effectively. The complex, which opened in October of 2012, is located between 13th avenue and Franklin Boulevard on the University of Oregon campus, and consists of offices and science laboratories that are joined by an unconditioned atrium. After a visit to the building, we were curious about the vents we saw on the wall and how they were utilised to heat the atrium. We wondered if the existing relief air vents are effective. We hypothesised that the air handling system in the LISB atrium releases air that travels upward toward the skylight rather than being distributed throughout the overall space. If our hypothesis were proven correct, this would prove that the relief air vents are not utilised effectively. In order to decipher if the exhaust heat is dispersing the air throughout the atrium, we decided to study where the air is moving through the space and what the difference in air temperature is throughout the atrium. This study was intended to determine where the heat from the air vents is flowing and whether or not they are the main heat source. Our methodology consisted of visually testing the air path and quantifying temperature differences in the atrium. Overall, we determined that the relief vents in the Lewis atrium were not utilised effectively because the general air flow in the atrium, detected by the bubbles, is pushing the air toward the eastern end of the atrium. We have concluded that the relief air vents are not the main heat source for the atrium. Since the atrium is surrounded by labs on the north and south side and borders Streisinger on the west end—the atrium is well “sandwiched” between insulating layers—the building’s heat loss is significantly low. Also, an efficient thermal envelope is achieved by having triple pane LEED certified windows on the ceiling and the glass curtain walls. Overall, our analysis shows that the main heat source of the atrium is the solar heat gained from the skylight and the south-facing window.

Optimization of DNA Extraction from Dried Blood Spot Samples for Use in a Telomere Length Assay

Presenter: Devan Compton

Mentors: Kirstin Sterner and Josh Snodgrass, Anthropology

Poster: 13

Majors: Anthropology and Psychology 

Telomere length (TL) is a marker of senescence, yet little is known about the specific factors that influence the performance of the TL assay. The World Health Organization’s study on global AGEing and adult health (SAGE) is investigating patterns of aging. As part of this study, dried blood spots (DBS) are being collected from adults in six countries in regions of different economic development. Before measuring TL, it is necessary to assess DNA quality obtained from DBS under various conditions. We tested if storing DBS at -20°C allows for recovery of optimal amounts of high-quality genomic DNA compared to -80°C. As DBS collected from finger pricks vary in size, we also considered the size of DBS (25uL vs. 50uL) to determine whether size affects the quality and quantity of the DNA extracted. Preliminary results indicate that 3.2mm (1/8”) punches from 50uL DBS yield nearly twice the amount of extractable DNA as 3.2mm punches from 25uL DBS. Additionally, DBS stored in a -80°C freezer yield approximately 47% more double-stranded DNA than DBS stored in a -20°C freezer. Lastly, we plan to determine the minimum quantity of DNA (three, four or six 3.2mm DBS punches) necessary to perform a successful TL assay. Methodological issues are key considerations in epidemiological research. This study will allow for optimal collection of DBS for DNA extraction as well as downstream use of the DNA in assays such as the TL assay.

Charge Trapping in Colloidal Cadmium (II) Selenide Quantum Dots

Presenter: Samuel Estrella

Faculty Mentor: John McGuire

Presentation Type: Poster 13

Primary Research Area: Science

Major: Physics

Quantum Dots are widely studied in hopes of using their tunable emission and absorption for photovoltaics and solar cells. Quantum dots are very small lattices containing around ten thousand to one million atoms. Due to their small size, it is easier for an electron that is excited from the core to reach the surface. The dangling bonds on the surface reduce the quantum efficiency of the dots by trapping carriers and preventing emission while trapped. Passivating these dangling bonds so carriers don’t get trapped is necessary to continue observations on more complex systems. Performing transient absorption with a 100 femtosecond laser, we were able to observe trapping in the quantum dots. We probed Cadmium (II) Selenide quantum dots that were treated with chlorine and mercaptoundecanoic acid ligands to passivate charge trapping on the surface and to prevent aggregation. The treatments that were used to passivate the surface traps showed no significant decrease in trapping. While we were not able to observe any benefit from the treatments, our collaborators at the Korea Institute for Science and Technology are developing different treatments to use on quantum dots. Upon decrease of trapping, quantum dots will be useful for quantum computing, biological marking, optical processing and tunable absorption and emission.

Chemotaxis Expansion Waves in E. Coli

Presenter(s): Maria Dresser − Physics, Mathematics

Faculty Mentor(s): Tristan Ursell, Daniel Shoup

Poster 13

Research Area: Biophysics

Funding: Presidential Undergraduate Research Scholars (PURS) recipient

Communities of bacteria respond to environmental changes as a group with the combined behaviors of individual bacteria giving rise to unique collective behaviors that facilitate the growth and dispersal of bacteria. In particular, bacteria undergo a process called chemotaxis which utilizes a run and tumble method to move towards higher concentrations within a given chemical gradient. In liquid environments, collective consumption and chemotaxis towards nutrients results in a collective behavior known as an expansion wave which facilitates rapid range expansion. How environmental properties dictate the attributes of expansion waves is poorly understood yet critically important as expansion waves drive invasiveness, colonization, and may help bacteria define their interspecies boundaries in complex communities. Here we study the expansion of E. Coli in capillary tubes to replicate a one dimensional expansion environment. The use of various concentrations of galactose and three amino acids give rise to different expression profiles and observable behaviors. After inoculating cells into capillary tubes containing different nutrient media, we image the tubes using bright field microscopy and measure the wave speed and number of waves in each tube. Wave speed allows us to understand how quickly bacteria enter a new region and how this is affected by nutrient concentration. Because different waves may exhibit different phenotypic states such as consuming different nutrients and undergoing cell division at different rates, we are interested in understanding what nutrient concentrations give rise to multiple waves. We hypothesize that slower waves are undergoing cell division more rapidly, thus devoting more energy to division than to consumption. Results thus far show that expansion rate is constant until a threshold is met, and lower initial cell concentrations give rise to more waves.

Gait Stability Deficiencies in Healthy Veterans and Veterans with Chronic Mild Traumatic Brain Injury

Presenter(s): Ravahn Enayati

Faculty Mentor(s): Li-Shan Chou & Will Pitt

Poster 13

Session: Sciences

While mild traumatic brain injury (mTBI), or concussion, is typically associated with athletics, head trauma is widespread in the battlefield and combat training, as evidenced by 294,010 documented cases of mTBI in the Department of Defense between 2000 and 2016. It has been shown that veteran subjects with chronic mTBI continue to suffer from subjective symptoms. It is reasonable to believe they may also continue to exhibit impairment in their gait stability when tested under a dual-task condition. Eight healthy veterans (1F; 33.93.8) and eight veteran subjects diagnosed with chronic mTBI (1F; 32.36.5 years old) had their gait imbalance tested. Each subject walked barefoot in two conditions. The first condition involved each veteran providing their undivided attention toward their movements (single-task). The second condition had each subject concurrently completing a continuous auditory Stroop test, which consisted of the individual listening to different auditory stimuli and attempting to correctly identify the pitch (dual-task). A camera motion analysis system was used to collect imaging of each subject’s movements during both conditions. A significant difference was found in medial-lateral displacement (p=0.007) and in the interaction effect of group and condition for peak medial- lateral velocity (p = 0.012). These results indicate that the veterans that suffer from chronic mTBI suffer from certain gait imbalances compared to a control veteran cohort. This information can be used to understand the physiological effects of chronic mTBI and to develop policy for the protection of mental health of military personnel.