Tag: Poster 20

Does Spatial Attention Influence the Severity of Visual Crowding?

Presenter: Daniel Klee

Mentor: Edward Awh

PM Poster Presentation

Poster 20

The identification of a target in peripheral vision is severely impaired in the presence of nearby distracting information. This phenom- enon is referred to as visual crowding, and it constrains important visual processes, such as object recognition and reading. Although a popular model of crowding attributes perceptual degradation to the compulsory averaging of target and distractor feature values, recent work by Ester, Klee, & Awh (in prep.) suggests that crowding is the result of feature mislocalization and a subsequent “swapping” of target and distractor feature information. Decades of research have shown that when an observer directs attention to the location of a stimulus, perceptual processing of that item is enhanced. Here, we examined the consequences of spatial attention on visual crowding. Our findings show that spatial attention attenuates crowding effects by reducing confusions between target and distractor values. The critical spacing distance for crowding – defined by the largest distance between targets and distractors where crowding is observed – was unaffected by spatial attention. These findings shed light on the basic mechanisms by which visual attention can ameliorate the harmful effects of nearby distractor stimuli.

Biomechanical Changes in Obstacle Crossing During Walking Following Concussion in High School Athletes

Presenter : Michael Kado

Mentor : Li-Shan Chou

Major : Human Physiology

Poster 20

Approximately 136,000 sports related concussions are diagnosed within the high school athletic population annually with little known about the longitudinal impairments that follow. The objective of this study was to investigate the longitudinal effects of concussion on gait during an obstacle-crossing task. Concussed subjects (n=20) were diagnosed by a physician or certified athletic trainer. Control subjects (n=20) were matched by height, weight, age, and sport participation and examined in similar time increments. Gait variables examined were average walking speed, step length, step width, cadence, and obstacle clearance height during an obstacle-crossing task. Subjects were tested at 72 hours, 1 week, 2 weeks, 1 month, and 2 months post-concussion. We hypothesized that concussed subjects would have decreased average walking speed, step length, cadence, obstacle clearance height, and increased step width compared to control subjects. Motion data was collected using 29 reflective markers and a 10-camera motion analysis setup. Subjects were instructed to walk over an obstacle set at approximately 10% of their height. Of the five variables investigated, step length and width showed the greatest differences between groups. Step length of concussed subjects was less than control subjects over the two months. Additionally, step width of concussed subjects was greater over the two months following injury. These results suggest altered walking performance while crossing obstacles in concussed individuals while recovering.

Architectural Design, Light Exposure, and Microbial Viability in the Built Environment

Presenter: Kyla Martichuski

Mentor: Jessica Green

Poster: 20

Major: Biology/Human Physiology

Researchers working at the intersection of biology and architecture have begun to investigate how building design structures the microbial communities of indoor environments. Given that we spend approximately 90% of our lives indoors, there is great potential to impact human health by incorporating biological understanding into building design. Ultraviolet light and direct daylight have well-known detrimental effects on the growth and viability of bacteria, but this relationship has not yet been applied to indoor environments. We designed an experiment to test how different architecturally relevant daylighting schemes impact the viability of microorganisms in the built environment. We constructed 3 sets of 1:32 scale models of a classroom with window glass panes transparent to either UV, visible, or no light. Bacteria were grown on media at 15 distinct locations throughout the model to reproduce the distribution of light exposure in a typical classroom. We measured bacterial viability after one day of exposure to the respective light treatments. Levels of both UV and visible light typically experienced in built environments were found to significantly impact the viability of Pseudomonas monteilii and Escherichia coli—two human-associated bacteria commonly found indoors. Most notably, viability was reduced in areas near windows with higher light exposure.

This evidence could inform future decisions about lighting schemes in hospitals and other healthcare facilities where biological insight is crucial. This study aims to demonstrate that integrating biological knowledge into architectural decisions can create a bioinformed perspective on buildings that promotes human health.

Determining the Location of Connections Among Top Internet Service Providers in the United States

Presenter: Phillip Kriegel

Faculty Mentor: Reza Rejaie

Presentation Type: Poster 20

Primary Research Area: Science

Major: Computer Science, Mathematics

Funding Source: Research Experiences for Undergraduates (NSF), $1500 a month

The Internet is a network of networks. There are more than 40,000 networks that create what we understand as the Internet today. Understanding where and how these networks interconnect is important for the purpose of meaningfully investigating a wide range of critical Internet-related problems, such as the vulnerability of the Internet to physical damage, such as earthquakes or power surges. Published work on Internet topology and structure focus primarily on finding the existence of these interconnections, and characterize the structure of the Internet based solely on these connections. By using RIPE Atlas, a distributed traceroute software, in addition to other methods, it is possible to estimate which networks exchange traffic in which cities. The purpose of this thesis is to gain a better understanding of the geographic nature of the Internet by pinpointing exactly where these interconnections occur on a physical level. This project is able to provide a city level understanding of the autonomous systems present in each city, as well as which of those systems connect. This serves as a resource for further research.

Synthesis of 6,13-pentacene-incorporated [10]cycloparaphenylene

Presenter(s): Cyrus Waters − Biochemistry

Faculty Mentor(s): Ramesh Jasti, Brittany White

Poster 20

Research Area: Organic Chemistry

Funding: SAACS Summer Research Award

Cycloparaphenylenes (CPPs) have size-dependent optoelectronic properties: the HOMO/LUMO gap size increases as benzene subunits are added. This capacity to tune the band gap makes CPPs attractive for use in organic electronic devices. Similarly, pentacene shows promise as a component of photovoltaic cells because of its uniquely high capacity for singlet fission (SF), whereby one high-energy incident photon is harnessed to yield two lower-energy triplets. In devices sensitized to SF, two electrons can be pushed per photon, bypassing the Shockley-Queisser efficiency limit and doubling the photocurrent from specific wavelengths of absorbed light relative to traditional, silicon-based photovoltaics. Pentacene-incorporated CPPs combine the two structures in a fully-conjugated system, potentially allowing the size of the CPP to control the energy of light at which the pentacene undergoes SF. Here, the synthesis of 6,13-pentacene-incorporated [10]cycloparaphenylene was attempted. Suzuki coupling of selectively-linked curved precursors yielded a strained macrocyclic intermediate. Attempts at reductive aromatization of the macrocycle have successfully aromatized the CPP backbone but have failed to aromatize the pentacene unit, instead yielding either the insufficiently reduced diol or its overly reduced dihydrogen analogue.

The Role of Cortical Inhibitory Interneurons in Auditory Signal Detection

Presenter(s): Nadav Menashe

Faculty Mentor(s): Santiago Jaramillo

Poster 20

Session: Sciences

For years, researchers have been trying to uncover how different auditory areas in the brain allow us to segregate signals from a noise. The goal of this study was to use a mouse model to understand how two types of cortical inhibitory interneurons found in the auditory cortex, known as somatostatin-expressing (SOM) and parvalbumin-expressing (PV) interneurons, contribute to our perception of sound masked by noise. We hypothesized that suppressing the activity of auditory cortical SOM interneurons would decrease a mouse’s ability to detect a tone masked by noise when the background noise was composed of broadband signals. We expected a similar decrease when PV interneurons were suppressed when the background noise was composed of narrowband signals. To test these hypotheses, we taught transgenic SOM-ArchT and PV-ArchT mice how to perform a behavioral task where they had to determine if a pure tone was present in background noise. We then implanted optical fibers over their auditory cortex and they performed the same task while having their respective interneurons suppressed through an interaction between the light-sensitive ArchT protein and green light. We found that suppressing SOM interneurons decreased the percentage of trials in which the mice were able to detect a tone in all bandwidths of background noise, while suppressing PV interneurons did not affect performance, showing that they might not be important for mice to perform this task. These findings allow us to better understand the roles that different sources of inhibition play when detecting a sound masked by noise.