Stander Symposium Projects

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  Native and Non-Native English Teachers

  Rowaida Hamad S Alhabis

  Over the years, English has rapidly grown to the extent of outrivaling languages such as French which were previously prestigious. English’s accelerated development arises from the fact that it can be easily learned. Non-native speakers often opt to learn English as their second language. Consequently, this language has emerged as the preferred communication medium in most institutions, organizations and professional circles worldwide. Globally, everyone is striving to improve their competence in English. In their efforts, the majority often opt to enhance their expertise through the assistance of native speakers. Due to the enormous number of English Learners worldwide, it is obvious that most English teachers are non-native English speakers, and should not be looked down upon. According to David John Brining, non-native English teachers are faced by uncertainties when speaking the language they have to teach, and may therefore take on an aggressive attitude towards teaching the language (50). They become obsessed with the grammar and ignore minor but significant elements like linguistic appropriateness. However, he adds that non-native speakers are the best teachers since they can easily communicate with non-native students, as they have been through the process of learning English as a second language. In addition, Enric Llurda disagrees by pointing out that a lot of non-native English speakers have adopted English as their L1, and with the exemption of an accent, there is merely a distinction between them and native English teachers (118). The preference of native English speaking teachers is fuelled by the notion that they are inherently superior to their non-native counterparts. This presumption frames the focus of interest in this examination. The research specifically challenges the notion that native speakers are inherently superior teachers of English, compared to their non-native counterparts, through a detailed review of selected studies and an analysis of primary information collected from surveys. I hope to convince students that professionals who teach English as their second language are equivalently competent as their native colleagues.

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  Natural Language Processing: A Look Into How Computers Understand Human Language

  Brad Richard Sorg

  The semantic interpretation of the human language is very complex and diverse making natural language processing an interesting task for researchers and engineers. Natural language processing is a subfield of machine learning focusing on enabling computers to understand and process human languages. Although computers do not have the same intuitive understanding of natural language like humans do, recent advances in machine learning have enabled computers to perform many useful things with natural language like text classification, language modeling, speech recognition, and question answering. Computers are able to accomplish these tasks by learning the deep contextual representations of words including both the syntax and semantics. Through the use of recurrent neural networks, long short-term memory units, temporal convolution networks, and different language embedding models, computers have made significant strides in their ability to interpret and understand human language. With large volumes of textual data available and the need to structure the unstructured data source that is human language, the area of natural language processing will continue to be of interest.

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  New Natural Gas Site Locating in the Marcellus Shale Region PA

  Ryan P Young

  Natural gas is an important resource for many various reasons. In the current study, I aim to identify the best suited location for a new well using various factors and restraints. This resource is stored thousands of feet beneath the Earth’s surface, specifically in shale bearing layers. One shale unit in particular, the Middle Devonian Marcellus Formation, is of particular interest. It extends approximately six-hundred miles, covering large areas of the Appalachian Basin including Pennsylvania, West Virginia, Ohio, and New York. The area underlain by the Marcellus Formation is nearly 240,000 square kilometers (Kargbo et. al., 2010). However, most of the natural gas is located underneath Pennsylvanian land and therefore this state will be the focus of the study. Recent advancements in the extraction of this resource have led to an exponential increase in this industry. New techniques known as hydraulic fracturing and horizontal drilling have greatly influenced the efficiency of the process and therefore economic prosperity. Just in Pennsylvania alone, 2008 estimates show the creation of more than 29,000 jobs and $2.3 billion dollars in revenue (Kargbo et. al 2010). A previous study by Meng (2014) revealed significant landscape variables as driving mechanisms in well-site location. Higher elevation and wetlands were shown to be the most prone to natural gas sites while steeper slopes were correlated with lower probabilities. I will apply his findings and the use of GIS techiniques to identify the most suitable location for a new fracking site. For each of the variables, a suitability layer will be created. Once all of these layers are created, they will be combined in order to acquire an overall suitability score to determine the best suited location.

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  Nitrate contaminant tracing in surface and groundwater in the Great Miami River Watershed: Environmental Isotope Approach

  Rachel Kristine Buzeta

  The global population has increased exponentially causing several challenges surrounding sustainability, including greater food production needs. To meet these demands and boost agricultural productivity, more efficient practices and fertilizers are used. Synthetic fertilizers and other nutrient sources have resulted in water quality degradation and pollution. Much of the Great Miami River Watershed’s streams and aquifers in southwestern Ohio are affected by nitrate contaminants originating from anthropogenic sources including synthetic and organic fertilizer used for agriculture, human wastes (domestic, industrial, and municipal wastes), and urbanization. High nitrate concentrations cause ecological disturbances across all trophic levels. Nitrate levels greater than 10 mg/L also pose a danger to human health, if the contaminant reaches drinking water sources. Water quality monitoring stations report nitrate concentrations in surface and groundwater, but a nitrate contaminant source has not been identified. Here we used isotope ratios of nitrogen (δ15N) and oxygen (δ18O) in nitrates to identify sources for surface and groundwater. Initially we fingerprinted the isotopic composition of the main nitrate contaminant sources in the watershed. Our results show a distinct low δ15N for commercial synthetic fertilizers (0.4±4‰) and high δ15N for animal and human waste (13.0±1.3‰). Further sampling along the Great Miami Mad, and Stillwater River provides insights into contaminant sources contributing to elevated nitrate levels in each river. In general, the δ15N from river samples collected during the low river flow lies within a range of human and animal waste, whereas δ15N values of groundwater suggest that the nitrates might have been derived from soil organic matter or synthetic fertilizers. This research provides a regional baseline for nitrate contaminant source tracing and helps to better inform state and local water quality and nutrient management planning.

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  Nutrition Trends and Resources at the University of Dayton

  Alicia Marie Abele, Mary Grace Charleton, Serafino Anthony LaGalbo, Nora Catherine Sabo

  It is no secret that American college students often live off of restricting budgets and inconsistent schedules, both of which can contribute to poor nutritional habits and food choices. According to the Journal of the American Dietetic Association, “25 percent of college students gained more than 5 pounds over the course of eight weeks while transitioning to a college lifestyle. However, a lack of calories can also lead to fatigue and difficulty concentrating at school.” The Center for Disease Control also emphasizes this correlation between student nutrition and academic achievements. Due to the immense importance of nutrition, we investigated the relevance of this trend at the University of Dayton (UD). Our strategies involved researching the current nutritional resources at UD as well as surveying students and interviewing dietetics faculty. Our main goal was to comprehend the correlations between age, living situations, budget, food consumption and weight fluctuations. Our poster will demonstrate these nutritional trends among students and provide suggestions on how to improve dietary habits for the university as well as the students. In addition, we created a flyer for UD students to help spread awareness of the nutritional resources that are available on campus.

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  Object Classification using Neuromorphic Cameras

  Wes Baldwin

  This poster presents recent work in the implementation of dimensionality reduction for neuromorphic camera data using time-surfaces. Neuromorphically inspired cameras can operate at extremely high temporal resolution (>800kHz), low latency (20 microseconds), wide dynamic range (>120dB), and low power (30mW). Time-surfaces are an ideal tool to leverage machine learning on event camera datasets as they assist in noise removal while retaining a high degree of spatial and temporal information. Combining time-surfaces with transfer learning is advancing state-of-the-art performance for object classification.

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  Paddle Pro Design

  Rose J Schaffer, Allison Shaw, Abigail Marie Ward

  The group set out to design a product that makes a creek more accesible for children who are differently abled. A kayak paddle assistive device, the Paddle Pro, was designed that would be able to help those with minimal hand and core strength be able to paddle. This device can also be used as a training mechanism to help young children learn how to paddle a kayak, especially if it is their first-time kayaking. The Paddle Pro is a t-stand that attaches to the base of a kayak. It has a suction cup base with PVC pipe attachments that will provide support to the paddle. The ball and socket joint is connected to a “steering wheel” style attachment which provides a wide range of motion in order to create the right form for paddling a kayak. In addition, the group added Velcro hand straps that helped provide support to children with minimal hand strength.

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  Patience, Young Grasshopper: Identifying the fungal composition of the grasshopper microbiome

  Melani Muratore, Staci N Seitz

  Microbes inhabit many corners of the Earth, including the intestines of all animals. These intestinal microbes, collectively called the “gut microbiome,” provide numerous nutritional and regulatory functions for the animals they live in and thus play an important role in animal health. The fungal communities in insects, specifically, play a diverse, but important role in insect physiology, as well as insect control. The overall goal of this project is to identify the fungal communities in grasshoppers to enrich our knowledge in insect fungal microbiome. Questions that we wanted to answer were: “what is the composition of the fungal communities in the microbiome of grasshoppers?” and “what drives the composition of the fungal communities in the microbiome of grasshoppers?” In this study, we investigated the composition of the fungal community inside grasshoppers. The grasshoppers were collected in the summer of 2017 from a Texas prairie as part of a multifactorial micronutrient experiment. DNA was extracted from the grasshopper gut and submitted for sequencing by Zymo Research. After analyzing the sequencing results, we identified two fungal phyla that were present in all samples: Ascomycota and Basidiomycota. Within Ascomycota, the class Dothideomycetes is most prevalent. Within Basidiomycota, the classes Tremellomycetes and Ustilaginomycetes are most prevalent. Dothideomycetes are typically found as saprobes, or decomposers, that break down dead leaf matter. They are also commonly found on living plants, acting as pathogens or endophytes. Tremellomycetes are a type of pathogenic fungus that acts as a parasite toward insects and plants. Ustilaginomycetes, known as “smut fungi,” act as a parasite toward vascular plants. All of these classes of fungi are directly involved with plant matter. Further statistical investigation will be done to determine the drivers of the diversity of these fungal communities and their significance.

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  Perceived Peer Norms, Health Beliefs, and Their Links to Sexual Risk Behavior Among College Students

  Cassandra L Hartman

  Research has shown an increase in risk behaviors (e.g., binge drinking, risky driving, or unprotected sex) during emerging adulthood, a developmental period between the ages of 18 and 25 (Arnett, 2000). Sexual risk-taking is of particular concern due to negative consequences (e.g., unintended pregnancy, contracting a sexually transmitted infection) of this behavior becoming more prevalent, especially among college students (e.g., Turchik & Garske, 2009). The current study investigated how peer norms and personal beliefs about health may work together to explain engagement in sexual risk behavior among college students. It was hypothesized that in the context of strongly held health beliefs (e.g., high perceived susceptibility), the relationship between perceived peer norms surrounding sexual risk behavior and one’s engagement in risk behavior would weaken, while in the context of weakly held health beliefs (e.g., low perceived susceptibility), the relationship between perceived peer norms and ones engagement in risk behavior would strengthen. Further, it was hypothesized that the relationship between perceived peer norms surrounding sexual risk behavior and one’s engagement in risk behavior would be explained by low levels of health belief variables. One hundred and fifty six undergraduates (48 male, 108 females) anonymously completed questionnaires online about personal beliefs about health, personal and perceived peer engagement in sexual risk behavior, and demographics. Hierarchical multiple regression using SPSS tested if the positive association between perceived peer norms and sexual risk behavior was moderated by privately held health beliefs. Bootstrapping (Preacher & Hayes, 2008) was used to test mediation hypotheses. No support was found for health beliefs to moderate or mediate the association between peer norms and sexual risk behavior. There was a strong and consistent direct effect of peer norms on sexual risk behavior across all analyses.

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  Perceiving Place: A Social Design Case Study

  Annie Anne Brinkman

  Space is one of the most basic foundational systems for living things. No matter what happens in the world, it happens in a spatial setting. The specific design of that setting or place plays a large role in the lives of those within it. Other factors within place—factors that might inform design choices—also affect perception of place. Broad consensus exists in scholarly literature about the general role that history, culture, environment and social factors play into the perception of place. However, a confirmatory analysis of this model, especially in regards to the specific categories influencing perception, has yet to be conducted. Therefore, the purpose of this study is to expand upon and further explore the notion of such categories in space analysis. I am looking to find if the application of this method will reveal varying differences in internal and external perceptions, and the level to which they may or may not vary. I am interested in further exploring the ways in which such knowledge can then lend itself to the creation of more informed and effective neighborhood-based design, especially centered on bridging potential gaps in understandings of place with Dayton, OH. It is hoped that this research will educate not only designers, urban planners, and community leaders, but also the broader public as to what is affecting the spaces they are functioning within. Success with this approach will provide a powerful social model for advancing communication across various levels of perception, as well as cultures and languages.

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  Personality Risk and Protective Factors Moderate Associations of Relationship Contingent Self-Esteem with Mental Health and Relationship Outcomes

  Frane Francis Santic

  Relationship Contingent Self-Esteem (RCSE) involves one basing their self-regard on the nature and outcome of their relationship (Knee, Canevello, Bush, & Cook, 2008). RCSE is said to occur from a thwarting of basic psychological needs, including competence, relatedness, and autonomy (Deci & Ryan, 2000, Knee et al., 2008). When these needs are not fulfilled, issues such as feelings of incompetence, a lack of feeling of control, and issues with connecting with other individuals can occur (Hadden, Rodriguez, Knee, & Porter, 2015). Further, those high in RCSE can have lower relationship satisfaction and experience higher levels of negative emotion felt (Knee et al., 2008). The objective of the proposed study is to examine how certain personality risk and protective factors that are correlates of the basic psychological needs influence the relationship between RCSE and relationship satisfaction and the experience of negative emotion (i.e., depression). The study draws from a large sample of married alumni from a private Midwestern US university. Participants were asked to complete a survey containing a range of measures that examine attachment styles, need fulfillment, and other personality factors, as well as what level of depression and satisfaction participants are currently feeling in their lives. Based on moderation analyses, the basic psychological needs were not found to moderate the relationship between RCSE and relationship satisfaction, with the exception of low competence in male participants. For both males and females, low levels of the autonomy and relatedness, as well as high levels of self-alienation, accepting external influences, and anxious attachment were found to moderate the positive association between RCSE and depression. Low levels of self-compassion, competence, and authentic living were found to only moderate the positive association between RCSE and depression for female participants.

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  Photoisomerization of Azobenzenes Inserted Into A Supramolecular Aggregate

  Caroline O Piekarski

  The purpose of this research project was to develop photomolecular systems that contain photoresponsive properties. Light provides a convenient and sustainable source of “green” energy for manipulating and powering nano materials and biomaterials. The primary molecules focused on in this experiment were two azobenzene derivatives: azobenzene 4,4’-dicarboxylic acid (ADA) and 4-dimethylaminoazobenzene-4’-carboxylic acid (M0423). Some azobenzene chromophores undergo cis-trans isomerization when irradiated with UV and visible light. Of the derivatives chosen, only ADA showed photoisomerization capability in its non-aggregated form. A series of dilutions and titrations were performed in order to induce and observe the formation of homo-aggregates of ADA and M0423, and hetero-aggregates containing both molecules. Aggregate formation was monitored using both UV-Vis absorption and circular dichroism spectroscopy. The experiment showed that both ADA and M0423 form aggregates in acidic conditions. Moreover, both ADA and M0423 are achiral but their 1:2 aggregate showed a quite intense CD signal indicating the formation of a chiral assembly despite the absence of any chiral template. The azobenzene-based systems were irradiated with UV and visible light in order to investigate their photodynamic properties. Irradiation experiments showed that the homo-aggregate of ADA is not able to photo-switch while the hetero-aggregate shows some photo-switching capabilities. Future studies will involve the analysis of additional derivatives and an array of hetero-aggregate to better understand their structure and its correlation with photo-isomerization.

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  Photoluminescence study of Ga-free and Ga-containing Sb-based superlattices for mid-infrared applications

  Logan Edward Cordonnier

  The goal of this project was to compare the quality of the Ga-free superlattices, InAs/InAsSb, to those of the Ga-containing structures, InAs/GaSb, for possible use as mid-infrared detectors. By using a 532 nm laser, two experiments were conducted. In one experiment, the temperature was fixed at 5 K and the laser power was varied between 10 and 2000 mW. In the other experiment, the laser power was fixed and the sample temperature was varied. The data was analyzed to determine various material parameters. The values of these parameters provided valuable information about the quality and the differences between these two structures. Based on the results of this type of sample characterization, it was clear that the Ga-containing superlattices outperformed the Ga-free ones.

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  Photometric and Chemical Kinetic Studies of Singlet Oxygen Quenching by Native and Acid-Blue β-Carotene: Implications for the 515nm Effect in Photosynthesis

  Claire Elise Hendrickson, Ashlee Wertz

  β–carotene (βC) is an orange pigment present in green plants, where it plays a protective role against the harmful effects of light. It does this by deactivating “singlet oxygen”— a toxic oxidizing species generated during photosynthesis. During photosynthesis, βC temporarily converts from its “native orange βC” state to a “pink βC” state. We hypothesized that pink βC will quench singlet oxygen less efficiently than native orange βC. To test this hypothesis, we chemically modeled pink βC with “blue βC–TCA complexes”, created by reacting βC with trichloroacetic acid (TCA). The singlet oxygen quenching efficiency of native βC and βC–TCA complexes was characterized in two ways. First, in the summer of 2017, we measured the rate of degradation of the singlet oxygen substrate DPBF in the presence of native βC and βC–TCA complexes. Second, in the summer of 2018, we used a near–infrared photometric detector to measure the intensity I1270 near–infrared 1,270 nm light emitted by singlet oxygen in the presence of native orange βC and blue βC–TCA complexes. Surprisingly, our DPBF–based and I1270–based results all indicate that native orange βC and blue βC–TCA complexes quench singlet oxygen with roughly equal efficiency. In the summer of 2019, I will use the Chemistry Department’s computational Gaussian software to characterize the sensitivity of the triplet state of βC (3βC) to the presence of electrically polarized environments such as those present in βC–TCA complexes and in pink βC. Because 3βC likely plays a crucial role in the deactivation of singlet oxygen, and because βC–TCA complexes are structurally similar to pink βC, these studies will provide new insights into the role of pink βC in photosynthesis.

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  Picard's Successive Approximation vs. Banach's Contraction principle

  Leah Marie Squiller

  The existence of a unique solution to the initial value problem: x’(t)=f(t,x) x(t0,)=x0 , can be obtained employing Banach’s contraction principle or Picard’s successive approximation method. Generally, the norm that is used in the contraction principle is the supremum norm that requires a condition that is not needed in the successive approximation method. Therefore, it seems as if the successive approximation method is a superior method. The objective of this project is to show that these two methods are equally efficient. This is due to the fact that the condition that was needed in the contraction principle can be eliminated by using a different norm that is equivalent to the supremum norm.

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  Place-Based Community Engagement and the Development of Self-Authorship in Undergraduate Women of Color

  Ajanti Simone George

  A central goal of higher education professionals is to promote self-authorship within the students that they serve; that is, helping students develop their internal capacity for discerning who they are in relation to their identity, values and social exchanges. Place-based community engaged learning challenges colleges and universities to assess the degree to which their espoused values of citizenship and activism at the institutional level are aligned with their actions; it is a multi-layered approach that requires institutions to reexamine policies that are rooted in oppression and maximize reciprocity. Understanding the historical context surrounding a university in relationship to community engaged efforts is especially important as institutions pursue racial equity and a more diverse student body. More specifically, understanding the experiences of women in color in higher education is key to uncovering the ways in which their racial identity plays a role in their unique interpretation of community engaged efforts and how they subsequently learn to negotiate their own values and beliefs rather than assimilate to the majority. The purpose of this qualitative phenomenological study is to better understand the impact that participation in place-based community engagement has on the development of self-authorship in self-identified undergraduate women of color at the University of Dayton. Grounded in the constructivist paradigm, this study is intended to further the profession’s knowledge about how practitioners can partner in student learning as they grow in their own awareness of self, with a nuanced understanding of a diverse sub-population.

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  Possible pharmacologic glioma treatment in Drosophila model

  Jenea Imani Adams, Kaitlyn M Alleman, Luke Alan Bressler, Karishma Sanjay Gangwani, Kathleen Theresa McCaslin, Katie Katherine Parker, Kirti Snigdha, Claire C Sullivan

  Glioma is a lethal brain cancer, and current treatment strategies have limited effects by extending life only by a few months. Thus, efforts should be made to discover better inhibitors of glioma growth. Ideally such inhibitors will suppress the progression of glioma by (a) inhibiting the underlying molecular pathways activated in glioma, or (b) prevent rapid proliferation of the glia and other cells that encompass the glioma tumor. We have developed a glioma model by co-activating PI3K and Ras/MAPK specifically in the Drosophila CNS glia. The Drosophila glioma cause the larval brain to appear enlarged due to rapid increase in the stem cells and their glial and neural progeny. These tumors cause the larvae to enter a prolonged larval phase, and eventually kill the organism. We are conducting a chemical screen using Tyrosine kinase inhibitors (Selleck Biochem.) in which we feed early third instar (72h old) larvae 10 or 300uM chemicals in DMSO and then see effects on glioma growth, and survival in mature third instar stage (120h old). Using these metrics, here we present data from our screen pertaining to drugs from rows A, B, C, and D of our library. Once we identify potential glioma inhibitors in the primary screens, we will validate them in secondary screens.

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  Poverty and Education

  Alexandra Gisela Delgrande, Ryan Earl Evensen-Hein

  Poverty affects at-risk students’ academic opportunity through its effects on academic achievement, motivation, development, and education quality. Impoverished at-risk students’ academic achievement is affected by their inability to acquire basic needs. This can be shown by these students’ graduation rates, math scores, and retention rates. There is evidence of poverty having a negative effect on graduation rates, retention rates, and test scores. These students’ can appear less motivated or less engaged in the classroom potentially due to their focus on higher priorities. How could you expect a student to worry about a math test when they do not know how they are getting dinner that night? Since these students are unable to acquire their basic needs, they can also encounter developmental problems. These developmental issues refer to social, emotional, and cognitive development as well as can lead to malnutrition and preterm birth. These developmental setbacks hinder these students’ ability to further develop in school. Another obstacle impoverished students can face is poor education quality. Oftentimes, inexperienced or ineffective educators are assigned to schools with higher impoverished student populations. This unfortunate fact, as well as underfunded districts, and the lack of basic school supplies, further disadvantage impoverished at-risk students. Impoverished at-risk students are put at a disadvantage through poverty’s effects on academic achievement, motivation, retention, development, and education quality.

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  Prenatal Care in Latin America

  Siobhan Kathleen Kenny, Molly Anne Quinn

  Each year, 529, 000 women worldwide die from complications during pregnancy and childbirth, of these 529,000 deaths 22,000 are from Latin America and Caribbean regions (Lubbock & Stephenson, 2008). Nicaragua, one of Latin America’s poorest countries, has a high maternal death rate due to lack of access to services, high fertility rate among a young reproductive age group, complications from unsafe abortions, postpartum hemorrhage, hypertension, and sepsis (Lubbock & Stephenson, 2008). Unlike Nicaragua, Cuba, a fellow Latin American country, has strict policies and procedures for prenatal care. Cuba’s use of the polyclinic, a multidisciplinary professional team that works closely with mothers and children in the community, allows for expecting mothers to have access to basic medical care, such as universal screenings and annual checkups, as well as access to medical educational materials and other necessary preventative care. A preventative approach to prenatal care includes prioritizing and tracking high risk pregnancies, and setting national standards that make the life expectancy at birth on par with western nations (Bragg et. al, 2012). As a result of Cuba’s approach, their maternal mortality rate is on the decline while Nicaragua’s’ in on the rise. The purpose of this poster is to describe the prenatal care disparities between Latin American countries, and offer some strategies to combat this problem.

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  Pretrial Publicity and Juror Decision-Making: Effects of Inadmissible Confession Evidence and Coverage of Its Exclusion from Trial

  Rebecca S Rhein

  The courts have long been concerned that exposure to media coverage regarding a case making its way through the judicial process (i.e., pretrial publicity [PTP]) may influence jurors’ decision-making in court. Indeed, empirical research over the past two decades has shown that PTP can influence juror decisions. PTP often contains descriptions of evidence or factors that are ultimately deemed inadmissible at trial (e.g., confession evidence), but no research to date has examined what occurs when confessions are reported to the public but later deemed inadmissible. We examined these issues using a 2 (Interrogation Quality: High vs. Low) x3 (Exclusion: Technicality vs. Cause vs. Not Specified) +1 (No Confession PTP Control) +1 (No PTP Control) mock juror experiment. Undergraduate students were randomly assigned to read various forms of pretrial publicity. In a second session conducted two days later, participants read a trial transcript that omitted any mention of the critical evidence contained in some versions of the PTP. Participants evaluated the evidence and rendered a verdict. Participants who were exposed to pretrial publicity were nonsignificantly more likely to find the defendant not guilty than those who received no pretrial publicity. When participants were not told the reason for the exclusion of the confession, they were more likely to convict the defendant. This may reflect a tendency of jurors to fail to disregard inadmissible evidence unless convinced of a rationale for its exclusion.

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  Propionate Perturbation of Listeria monocytogenes Growth and Listeriolysin O Production is Modulated by Anaerobicity

  Jack Clifford Weis

  Propionate is a common food preservative and one of the major short chain fatty acids in the human intestines. Therefore, exposure to propionate is a frequent event for foodborne pathogens and likely takes place under suboxic conditions. However, it is not clear whether the absence of oxygen affects how pathogens respond to propionate. In this study, we investigated how propionate exposure affects Listeria monocytogenes growth and virulence factor production under aerobic or anaerobic conditions. Under anaerobic conditions, propionate supplementations had no effect on planktonic growth but resulted in decreased adherent growth. In contrast, under aerobic conditions, propionate supplementations resulted in a pH-dependent inhibition of planktonic growth and increased adherent growth. The effects of propionate on planktonic growth are also temperature-sensitive. At room temperature, propionate supplementation resulted in decreased doubling times under aerobic but not anaerobic conditions. To begin to investigate the effects of oxygen on L. monocytogenes response to propionate, we further noted that supernatant from cultures grown with propionate contained an increased amount of acetoin under aerobic conditions and a decreased amount of ethanol under both aerobic and anaerobic conditions. Moreover, L. monocytogenes grown with propionate exhibited an increased proportion of odd number straight chain fatty acids in a manner that was more pronounced under anaerobic conditions. Finally, aerobic suppression of listeriolysin O (LLO) production and anaerobic induction of LLO production were observed in L. monocytogenes grown with propionate. These results clearly demonstrate for the first time that L. monocytogenes exposure to propionate resulted a variety of physiological and pathogenic responses. Moreover, the presence or absence of oxygen plays a critical role in shaping L. monocytogenes responses to propionate that can potentially impact bacterial survival in the environment and subsequent interactions within host cells.

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  Pseudomonas aeruginosa biofilm and the properties of polysaccharide associated antibiotic resistance

  Celeste Claire Bergman

  High density growth of bacteria tend to form biofilms by excreting an extracellular matrix. This matrix is composed of adhesive components such as polysaccharides. The polysaccharides serve as cell-to-cell attachments and a selective filter for which outside material must pass. By forming the biofilm, the bacteria create a defense mechanism against antibiotic attacks and other abrasive environmental factors. Pseudomonas aeruginosa is a biofilm forming bacteria with known antibiotic resistance. Four strains were tested, ΔwspF, ΔwspF Δpel, ΔwspF Δpsl, and ΔwspF Δpel Δpsl. Each strain produced differing amounts of the polysaccharides PEL and PSL. The antibiotics gentamicin and ciprofloxacin were used to test antibiotic tolerance of the differing polysaccharides. The results showed that PSL provided antibiotic tolerance against gentamicin but was susceptible to ciprofloxacin. PEL provided antibiotic tolerance to ciprofloxacin but was susceptible to gentamicin.

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  Quaternion Neural Networks for Sequence Classification

  Cameron E Long

  Recently the field of deep learning has made significant advancement, included in this category is the subject of sequence classification. Recent research has shown that traditional sequence processing deep learning architectures such as the Long Short-Term Memory cell (LSTM) or the Gated Recurrent Unit (GRU) can be replaced by Dilated Fully Convolutional Networks called a Temporal Convolutional Network (TCN). Other research has shown that by representing deep networks with complex and quaternion numbers, the networks tend to show improved convergence while using significantly less learned parameters. We combine these two observations to create a Quaternion Temporal Convolution Network (QTCN), and show its performance on sequential classification tasks.

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  Rapid Miocene Extensional Unroofing of the Southwestern East Humboldt Range Metamorphic Core Complex, Nevada

  Alex Jakob Carte

  The Ruby Mountains and East Humboldt Range of northeastern Nevada expose exceptionally high grade metamorphosed rocks, the tectonic history of which has been hotly debated for decades. To resolve this debate, we collected a WNW-trending transect spanning 20 km of muscovite, biotite, and/or potassium-feldspar bearing samples for dating by the 40Ar/39Ar method. This method allows us to model the timing and progression of cooling, and therefore the uplift history of these rocks. The results from the southernmost transect indicate an early phase of cooling prior to 35Ma (See companion presentation by J. Jeruc). Here, I present results from the western flank of the range that record a later phase in the cooling history. A series of five samples from this transect imply that cooling below 200°C began prior to 30 Ma. The samples then cooled slowly until about 20-24Ma, when they experienced a reheating event to above 250°C. Following reheating, the samples cooled rapidly to below 100°C between 20 and 14Ma, with cooling occuring progressively later towards the WNW. The termination of cooling at 14 Ma is in excellent agreement with fault gouge dating results reported by Haines and van der Pluijm (2010). The progression of cooling ages implies that unroofing proceeded at a rate of 1.8 - 2.4 km/m.y. Although some researchers suggest that the chief trigger of this phase of extension was the drifting of western North America over the Yellowstone hotspot, these results indicate that the onset of extension predated hotspot related volcanism by at least 3 m.y.

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  Rational Bargaining Strategies

  Chloe Lynne Beckett

  Ariel Rubinstein proved a perfect equilibrium partition exists in a bargaining model. His results come from a game in which two players must agree on a contract that states how to partition a pie of size one. Several statements regarding the players’ preferences are assumed. To begin, one player makes an offer and the other player accepts the offer or rejects the offer with another proposal. The Perfect Equilibrium Partitions (PEP) are described in all the models satisfying the assumptions. Solutions to the above scenario using fixed bargaining cost and then fixed discounting factors will be displayed during the presentation.