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«Strengthening the Nation through Diversity, Innovation & Leadership in STEM San Antonio,Texas · October 3-6, 2013 Get Connected! Connect with the ...»

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Thermoelectric efficiency is proportional to the power factor (defined as the Seebeck coefficient squared times the electrical conductivity) divided by the thermal conductivity of the material. In most materials, the thermoelectric parameters are coupled in such a way that it is difficult to increase the efficiency. However, in recent research, silicon nanowires have proven capable of decoupling thermal conductivity from the power factor. They exhibit a reduced thermal conductivity while maintaining a relatively high power factor compared to bulk silicon. This causes silicon nanowires to have a roughly 100-fold increased thermoelectric efficiency. Our goal is to further increase this efficiency by enhancing the power factor of silicon nanowires. We fabricated an electrical gate around the nanowires, which allowed us to induce and control the carrier concentration in the nanowires. Then, we measured power factor as a function of gate voltage to find the maximum power factor. We also expected our method to work differently in nanowires of different cross sectional area, and, therefore, we evaluated our technique in nanowires of: 35 nm x 41 nm, 35 nm x 35 nm, and 35 nm x 27 nm cross sectional areas. We obtained a maximum power factor in the larger cross sectional area nanowires, yielding a power factor of 2 to 2.25 mW/m-K2. Using our technique, we achieved a power factor comparable to bulk silicon, which has not been accomplished before. This enhancement in efficiency can help make thermoelectrics more commercially viable.




Vito Iaia, Emin Menachekanian, Gary Williams.

University of California, Los Angeles, Los Angeles, CA.

By understanding the mechanisms of the two-dimensional (2D) Kosterlitz – Thouless (KT) onset of superfluidity in liquid helium-4 and how vortices play a part in this transition, a link to similar breakdowns in other super-materials, such as superconductivity in metals, could be better understood. In a cylindrical geometry such as a thin film coating a carbon nanotube, it is expected that the phase transition should change from 2D to a 1D regime when the vortex core size becomes equal to the nanotube radius. Vortices, which dictate the KT transition, are predicted to completely destroy the superflow in such a 1D regime. Initial measurements of superfluidity in thin films ranging from 3.5 to 6 atomic layers coating the surfaces of the nanotubes over temperatures varying from 150 mK to 1 K have been carried out. The amount of superfluid can be measured by creating oscillating temperature and thickness waves, via mechanical shaker, called thirdsound waves in the helium film. Resonance peaks of the third sound wave are analyzed via fast Fourier transforms (FFT), from which the third sound wave speed can be determined. From analysis, it is seen that the wave speed shows modulation at integer atomic layers. Furthermore, the results are fully consistent with the 2D KT theory. To get to the lower temperatures and thinner films to observe the 1D phase transition, a different suspension system for the experimental cell is currently being engineered, to try to reduce the heating effect of the mechanical shaker on the dilution refrigerator.



Edgar Segovia, Stephen Tsui.

California State University, San Marcos, San Marcos, CA.

In response to consumer demand for electronic storage capacity, there is a global undertaking to investigate memory phenomena in materials. Bipolar resistive switching, whereby the electrical resistance of a material is reversibly modified via application of a voltage of alternating polarity, has been extensively studied in oxide semiconductors. The goal of this research is to explore resistive switching in a YBa2Cu3O7 (YBCO) superconductor and how the switching responds to degradation of the YBCO using water. Several 500-nanometer-thick YBCO films were water degraded and then received deposited silver electrodes. The samples were subjected to voltage pulses of 1 microsecond

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Bryan Loeding, Max Hansen, Paulo Acioli.

Northeastern Illinois University, Chicago, IL.

The objective of our research is to design laboratory experiments and computational activities that accompany the first-year, calculus-based physics sequence. Rather than following the traditional sequence, the course uses a more contemporary approach by engaging the students in analyzing fundamental principles rather than secondary formulas.

It makes macro-micro connections, introducing the atomic nature of matter early. It introduces students to concepts of modeling by making idealizations, simplifying assumptions, and estimates. The course contains simple laboratory experiments and computational models to predict time evolution of system behavior. The same models can be used in other math-related coursework. The activities were developed in Python and were designed to engage in the process of learning physics through inquiry. The topics covered in these activities were motion, force and momentum, gravitational force, planetary motion, spring stiffness, and Young’s modulus. We started with suggested activities and modified them to consider the diversity of Northeastern Illinois University’s student population as well as their work-life balance needs as commuting students. Our considerations of the students’ needs will lead to the student engagement that is necessary for long-term retention of the concepts and materials. The effectiveness of these activities will be assessed in terms of concept retention and the attitude of the students toward physics.

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Ta’les Love, Christopher Benson, Janice Collins.

University of Illinois at Urbana-Champaign, Urbana, IL.

Despite the numerous spans of channels offered to the American audience, television shows with predominantly African-American casts have remained few in number. Scripted sitcoms such as Good Times or The Cosby Show, which are family-oriented and positive, have been replaced with the less expensive and more entertaining reality television shows of high profile professionals and entertainers. This entertaining realm tends to focus on the women in those worlds and often displays the ever-present stereotypes and image portrayals of the argumentative, angry, and unmarried Black woman. Through the analysis and coding of season 5 of The Real Housewives of Atlanta, our research analyzes whether Black women perpetuate or challenge their own negative stereotypes. The number of times the women’s actions or dialogue resembles a stereotype, such as in an argumentative or sexual manner, is recorded in an effort to reveal how frequently the stereotypes are displayed in a single episode and throughout the season. The working hypothesis is that African-American women uphold their own negative image portrayals in a media-driven and sexually-entertained society, even when these women are given the power to redirect certain beliefs.




Thomas Thompson, Ernest D. Hernandez.

University of Texas at San Antonio, San Antonio, TX.

This study examines the house price change based on neighborhood diversity in the San Antonio metropolitan Professional area over the 2003 to 2013 period. The study of house price appreciation is well researched and there has been Careers some research on how wealth is established among different racial groups. Flippen emphasizes the challenge in determining whether differential appreciation is due to race alone or socioeconomic factors which are correlated to race. MacPherson and Sirmans discovered that percent change of ethnicity was a greater indicator of fluctuation in price appreciation than the population fraction of a particular minority in an area. Our study is more micro in its focus (a single metropolitan area) and includes a period of increasing prices, decreasing prices and recovery of prices.

Our data are MLS transactions from 2003 to 2013 in the San Antonio metropolitan area and US Census Bureau data for the same areas. We study the effects of different demographic characteristics and trends such as household status, income level, education, and race/ethnicity as they relate to house price changes. A hedonic regression model allows us to both assess the changing house prices for a constant quality house, and to assess the impact of the demographic variables. Our preliminary findings show that homes in the highest valued and lowest valued neighborhoods declined more sharply in the current downturn and are struggling to recover. Median neighborhoods fully participated in the upswing, and were more quick to recover after the decline.

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ANALYSIS Gabriel Sanchez1, Jon Erlandson1, Eirik Thorsgard2.

University of Oregon, Eugene, OR, 2Flinders University, Adelaide, South Australia, AU.

1 Anthropologists have long believed that Native Americans on the northern Oregon coast did not actively hunt cetaceans; however, archaeological evidence could suggest otherwise. Our project uses ethnographic data, comparative artifact analysis, radiocarbon dating, and blood residue analysis to investigate whether whales might have been hunted during prehistoric times along the northern Oregon coast. A humpback whale (Megaptera novaeangliae) phalange with a bone harpoon point embedded in it from the Par-Tee site (35CLT20) may provide evidence of whale hunting. The dimensions of the embedded harpoon point were determined using computed tomography (CT) scanning in order to complete comparative analysis. Based on comparative analysis, 3 harpoon typologies were selected for blood residue analysis. This project has the potential to identify a previously unknown or unrecognized hunting technology within Oregon and may provide the basis for a reassessment of current archaeological collections if cetacean blood residues are identified. In addition, this project may provide a time marker for active or opportunistic whale hunting within Oregon.




RESPONDING Joy Deutschendorf, Adam Mills.

Oklahoma State University, Stillwater, OK.

This study examined anticipatory processing with participants high (HSA) and low (LSA) in social anxiety. We expected that HSAs and participants who anticipated would have the lowest heart rate variability (HRV), which measures physiological flexibility. A repeated-measures ANOVA examined HRV change between relaxation and attention tasks. In the anticipation condition, HSAs had no HRV change, as it was low throughout both tasks, but LSAs experienced a drop (p.001). In the distraction condition, LSAs had no HRV change, but HSAs experienced a drop (p.01). These results suggest anticipatory processing resulted in an anxiety increase for LSAs.

Behavioral Social & FRI-148


Sara Witcraft, Ashley Shaw, Eric Pedersen, Kiara Timpano.

University of Miami, Coral Gables, FL.

Hoarding disorder (HD) is characterized by chronic saving of one’s possessions and often excessive acquisition of items, resulting in clutter. HD can impose health and safety risks on individuals and is a major cost to the community.

Previous research has implicated trauma in the development of HD. The current study investigated the association of trauma with both self-reported and behavioral indices of hoarding symptoms. We hypothesized that frequency of traumatic life events (TLEs) would be associated with higher self-reported hoarding symptoms and greater hoarding behaviors. Undergraduate students (n = 80) completed self-reported measures of hoarding symptoms and TLEs, and behavioral measures of acquiring and saving tendencies. As part of a larger investigation, participants were randomized to either a psychosocial stress task or a nonstressful control task. Thus, the stress-task condition was controlled for in analyses of the behavioral measures. As expected, more frequent TLEs were associated with greater acquiring tendencies, including more items purchased (r =.24, p.05) and more money spent (r =.35, p.01) during the task, controlling for the stress-task condition. However, frequency of TLEs was not significantly associated


with saving behavior or self-reported hoarding symptoms. Results suggest that TLEs may be more important in acquiring tendencies than saving behavior, but future research should replicate this finding and use longitudinal designs to confirm the directionality of the findings. Clinicians may benefit from considering a patient’s history of TLEs when treating hoarding symptoms, especially for patients experiencing excessive acquisition.



Kayviann Hallers, Charisee L’Pree Corsbie-Massay.

Loyola Marymount University, Los Angeles, CA.

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