Category: Poster

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The Influence of Polyethylene Nanoplastics on The Toxicity of Methoxychlor on D. magna

by Thanh-Binh Duong

Faculty Mentor: Dr. Tyler Frankel

Nanoplastics (NPs), defined as plastic particles < 0.1 mm, have become an emerging concern in aquatic environments due to their multiple pathways of entry into rivers and streams. NPs may originate from the manufactured beads for personal care products as well as the from the fragmentation of larger plastic items. Due to their small size they are easily ingested by aquatic organisms, resulting in detrimental health effects such as digestive tract obstructions, feeding debilitation, and energy depletion. Due to their physiochemical attributes, NPs have also been shown to sorb and mobilize organic pollutants such as pesticides, suggesting that interactions between these two types of pollutants may result in an altered biological response compared to the effects of each individual contaminant. This study assessed the potential synergistic or antagonistic effects of polyethylene nanoparticles and the organochlorine pesticide methoxychlor on the viability and mobility of Daphnia magna. Adult D. magna were exposed to either 1) virgin 10-20µm polyethylene pellets, 2) methoxychlor, or 3) various combinations of the same pellet and methoxychlor concentrations for 48 hours or 7 days using a static exposure method. Mortality and paralysis were assessed per 24 hours of exposure. Mobility was assessed after 24 hours of exposure. To assess mobility, individuals were recorded in a light-controlled behavioral chamber for 3 minutes. Footage was analyzed using ToxTrac to quantify mobile speed, acceleration, and distance traveled. While this project is currently ongoing, we expect to find a significant difference in mobility parameters and mortality rates when exposed to the combination of polyethylene pellets and methoxychlor compared to the effects from each contaminant alone. Thus far, few studies have examined the ability of NPs to influence the toxicity of organochlorine pesticides in aquatic invertebrates. This study will help explicate the impacts of plastic pollution on aquatic biota in freshwater systems.

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The impacts of pH on trace contaminant leaching and toxicity of coal ash in Planorbella duryi

by Catherine Crowell

Faculty mentor: Dr. Tyler Frankel

Coal fly ash is a major industrial waste that is primarily produced by coal-burning power plants. Ash contains multiple trace contaminants that have the potential to leach into waterways after rain events, causing undesirable effects on aquatic species in these ecosystems. Few laboratory studies have examined the relationship between acidified rainfall and the release of trace metals from coal ash and the impacts of such rainfall on the toxicity of coal ash leachates on aquatic invertebrates. Thus, the goals of this study were to 1) evaluate the effect of varying pH’s on the leaching of trace contaminants from coal ash and 2) examine the impacts of these leachates on the viability, development, and hatch rate of embryonic Planorbella duryi, a freshwater snail species found in intermittent streams throughout North America. Briefly, 100g of coal fly ash obtained from a local coal ash repository was added to individual glass vessels containing 1L of synthetic water adjusted to pH’s of 4.5 to 7.5. After 48 hours, all leachates were vacuum filtered and an aliquot analyzed for aluminum, arsenic, calcium, cadmium, chromium, cobalt, iron, mercury, magnesium, manganese, lead, selenium, and zinc using ICP-OES. Embryonic P. duryi clusters (<2hrs old) were then exposed to each leachate for 10 days using a 48hr static-replacement assay, and the number of viable individuals and hatchlings in each cluster assessed daily. To examine the impacts on growth, photographs of each embryo were obtained every 24 hours. While this project is currently ongoing, we expect to find increases in aqueous trace contaminant concentrations as a result of decreased pH in leachates as well as decreased viability, growth, and hatching success. This study will provide important information regarding the potential impacts of acidified rainfall on the mobilization of trace contaminants and toxicity of coal ash leachates on aquatic invertebrates.

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Laser Harp

by Rebecca Callaway, Mary Dye, Adam Schoene

Faculty mentor: Laura Dickinson

Musical instruments are often discarded when the cost of fixing an issue becomes an inconvenience. Millions of dollars worth of instruments are thrown away each year while communities around the country struggle with funding art and music programs. This causes music to become a privilege and for certain instruments to be only associated with certain socioeconomic classes. A new system needs to be designed where students and teachers can be exposed to musical instruments without having to worry about financial constraint. Instead of disposing of an expensive instrument and adding to landfills, mass produced electronic components can be used to extend its functionality as an educational tool. Affordable light sensors are used in place of the core sound producing material on the instrument. Software is combined with the light sensors in a manner to reproduce the sound it would make with original materials along with the ability to manually change the tone. Due to an electronic interface, performance can be easily recorded in notation software to keep track of progress and enhance the musicians understanding of music.

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The Presence, Distribution, and Concentration of Microplastics In the Lower Basin of the Chesapeake Bay, USA Near Wastewater Treatment Plants

by Thanh-Binh Duong

Faculty Mentor: Dr. Ben Kisila

The Chesapeake Bay is a large estuary located along the east coast of the United States, with numerous wastewater treatment plants (WWTP) located throughout its basin. This area supports a vast diversity of aquatic biota and provides for numerous communities throughout the eastern United States. While effluent from WWTPs has been identified as a major contributor to microplastic pollution, little research has been conducted to examine microplastic contamination in the Chesapeake Bay watershed areas surrounding these effluent streams. Microplastics are unique in that their size (<5mm) enables ease of ingestion by aquatic organisms, causing adverse health effects such as energy depletion and digestive tract obstructions. MPs may also biomagnify throughout trophic levels, ultimately posing a threat to human health due to unintended consumption. In this study, the presence of microplastics in major rivers in the lower basin of the Chesapeake Bay, USA was examined. Water samples and sediment samples were collected in the Potomac and Rappahannock river upstream, midstream, and downstream of WWTP outfall sites via dip sampling and grab sampling, respectively. Sediment samples were treated with a wet peroxide oxidation using Fenton’s reagent to digest natural organic matter and sodium chloride to separate MPs from the sample. Surface water samples were filtered by vacuum filtration to separate suspended particles from water. Presence, type, and quantity of MPs were assessed using light microscopy. While this project is currently ongoing, we expect to find that MPs are more abundant in samples collected at WWTP outfall locations rather than locations upstream or downstream from those sites. The results of this study will provide novel information regarding the presence, distribution, and concentrations of MPs in water and sediment samples from several areas of the Chesapeake Bay watershed due to inputs from WWTP effluent.

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An Archaeological Analysis of a Possible Slave Quarter on the Little Falls Plantation in Southern Stafford County

by Lillian Salamone, Laurence King, Kathleen Keith

Faculty mentor: Dr. Lauren McMillan

Students in the introductory archaeology class at the University of Mary Washington conducted a preliminary shovel test pit survey of the site currently referred to as Little Falls-Norton Property in March and April 2018 and March 2019. These investigations were undertaken at the request of the landowners, who discovered archaeological material while doing yard work. The site is currently a residential lot, near Little Falls Plantation, which is in southern Stafford County, Virginia. The analysis and interpretation of the site was undertaken by the authors for a class project. Analysis of the artifacts, combined with archival research, indicates the site was likely an Antebellum slave quarter/Postbellum tenant site. This mid-19th-century site was likely an outlying field quarter associated with the larger Little Falls Plantation. This poster will detail the historical and archaeological evidence uncovered during the course of this project and outline suggestions for future research.

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Academic Podcasts & Posters for Political Science 370 Spring 2020:Women in Politics

by Karolina Albert, Emily Bowerman, Austin Chapple, Alexander Elvir-Herrera, Patrick Healy, Viviana Hernandez, Kate Jolly, Ailexondra Lloyd, Anna Longacher, Maryclaire Muskett, Khaila Nelson, Maeve Reilly, Savannah Roberts, Lauren Talbert, Stephanie Turcios, Eva Waszak

Faculty mentor: Professor Cooperman

The academic podcasts and posters from Professor Cooperman’s Political Science 370 course, Women in Politics, asked students to create an original research project that examined a specific relevant issue related to gender in contemporary U.S. politics. These projects examine topics such as women’s political candidacy, voter outreach in the 2020 election, the politics of reproduction and abortion, sexual harassment and discrimination policies, and health status of women of color.

Student Podcasts:

Karolina Albert
Emily Bowerman
Austin Chapple
Patrick Healy
Viviana Hernandez

Ailex Lloyd

Khaila Nelson

Savannah Roberts

Lauren Talbert
Stephanie Turcios
Eva Waszak

Student Posters:

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Food Waste

by Damon R. Cox

Faculty mentor: Dr. Kashef Majid

My project talks about the high amounts of food waste in America and around the word. It talks about problems that food waste causes, causes of food waste, and recommendations on how to slow down food waste.

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Error Related Negativity and Moderate Exercise

by Jade Turner, Peyton Dunow, Samara Wong, Julie Boynton

Faculty mentor: Dr. Emily Stanley

Previous research has found that moderate levels of exercise are related to improved cognitive functioning, along with increased P3 (stimulus evaluation) and decreased N2 (response monitoring), which are components of error processing. Previous studies have also shown an enhanced effect of exercise on executive functioning. The present study aims to determine whether athletes will have a smaller error-related negativity (ERN), another aspect of error processing, than non-athletes. This study will include giving the Flanker task while connected to an electroencephalogram (EEG), having participants bike for fifteen minutes, completing the Flanker task again, and measuring positive and negative affect, mental toughness, and intrinsic motivation as possible mediators. We hypothesize that participants who fit in the athletic category and all participants’ second trial will make fewer mistakes overall on the Flanker task and have a smaller ERN. We will also explore other factors to look for mediation in the relationship.

Error-Related Negativity
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Generosity of Spirit: Faith, Democracy, and Grace in Marilynne Robinson’s Gilead

by Elisabeth DellaRova

Faculty Mentor: Dr. Jonathan Levin

As my honors capstone and a culminating course for the English major, I have completed an individual study on the theme of grace and how it relates to the American experience in Marilynne Robinson’s work, specifically her three books Gilead (2004), Home (2008), and Lila (2014). The books are about the families of John Ames and Robert Boughton, who are preachers and lifelong friends living in the fictional small town of Gilead, Iowa in the 1950s. Through the books, Robinson presents her view on modern American Christianity, placing it in the context of American religious movements such as Transcendentalism, Puritanism, and especially Calvinism. I spent the semester reading many of Robinson’s essays, many of which focus on religion, grace, American history and politics, and Calvinism, as well as outside sources on American religious history, scholarly criticism of Robinson’s fiction, and interviews with Robinson. From my interactions with these readings, I have concluded that Robinson argues that the grace that comes out of American Christianity is synonymous with generous discourse and a generosity of spirit. She feels that this form of grace is becoming increasingly lost, or perhaps silenced, in American culture, especially since the mid-20th century when her books are set. Through her characters–John Ames, Jack Boughton, and especially, I will argue, Lila Ames–Robinson presents a display of the way this generosity of spirit should intersect with faith and democracy in our nation.

ENGL-491-_-Honors-Capstone-Paper-Elisabeth-DellaRovaDownload
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Fantasmas o Fantasia: Un Análisis de Casa tomada

by Christopher Good

Faculty mentor: Dr. Marcelo Fajardo-Cárdenas

Literary analysis of Casa tomada (House overtaken), a short story written by Julio Cortazar in his book: “Bestiario” (bestiary). The story has features of magical realism, mystery, and horror in its account of two siblings whose home is overtaken after hearing strange sounds. This essay was written by a student in Professor Fajardo-Cardenas’ writing-intensive, Advanced Writing class (Spanish 413).

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Evaluation of Metal Contamination and Soil Properties at Former Mine Sites in Poland

by Kaitlyn McClung and Emily Brooks

Faculty mentor: Dr. Melanie Szulczewski

Surface mining dramatically affects the environment, both where the resource extraction takes place and in the areas where mining wastes and overburden are deposited. Poland is Europe’s top coal producing country and is also home to many mines for pyrite, sand, and other mineral resources. We studied soil samples from three former mining areas in Poland: the Bełchatów and Smolnica coal mines, and the Piaseczno sulfur mine. Various substrates, amendments, and trees had been used for remediation, with activities taking place up to 36 years previously. The success of reforestation and soil development varied greatly, especially in pH, organic matter, and metal concentrations.

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Investigating reproductive success and endocrine regulation of mating strategies in male medaka

by Lauren Closs

Faculty mentor: Dr. Dianne Baker

Mate guarding, when two males compete for one female, is a reproductive strategy seen across a variety of vertebrate species. This often leads to hierarchical relationships, in which one male exerts dominance over other, subordinate males. However, the physiological mechanisms that promote dominance or subordinance in males remain largely unexplored. This study investigates the reproductive success and endocrine signals of these reproductive strategies in Japanese medaka (Oryzias latipes). To identify dominant and subordinate males, triads consisting of two males of different genotypes and one female were observed repeatedly for 5 days. Male reproductive success was determined by genotyping embryos from each female. We found that the number of eggs fertilized by dominants and subordinates did not differ (p=0.29), indicating that dominant behavior does not guarantee reproductive success and that subordinate males may successfully fertilize eggs using sneaker male tactics. We hypothesized that these behaviors are linked to activity in the reproductive endocrine axis. To test this hypothesis, we quantified pituitary luteinizing hormone (LH) and follicle stimulating hormone (FSH) in dominant and subordinate males using ELISAs. While FSH did not differ between the groups, LH was unexpectedly higher in subordinate males (p=0.047). This indicates that either LH production is stimulated, or its pituitary release is inhibited in subordinates. To investigate these opposing explanations, we measured mRNA levels of LH, FSH, and GnRH receptors in the pituitary, and GnRH and AVT in the brain of dominant and subordinate males using qPCR. Mean differences between dominants and subordinates were not significant for any gene. Dominant fish expressed higher lhb in 8/12 tanks, indicating that LH production is not stimulated in subordinates, but as the transcripts for GnRH and its receptors also did not differ, further studies are needed to determine the mechanism by which LH release may be inhibited.

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What Is CBD And Why Should Employers Be Aware?

by Leslie Miyazono

Faculty mentor: Dr. Alexandra Dunn

Cannabidiol (CBD) is a chemical compound present in the cannabis plant, which can be sued medicinally as a remedy for a variety of ailments and pain management. The varying nature of CBD products on the market may present some obstacles for employers. Will CBD trigger a positive test result and inadvertently violate a valid workplace drug policy? This project will discuss the current classification, various legislation, and approved uses of cannabis derived products such as CBD. The need for various workplace drug policies will also be reviewed. The purpose of this project is to generate awareness to employers on the evolving CBD marketplace and the multiple layers of complexity of this topic in order to decide if current drug policies need to be amended or revised.

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Assessing the presence and concentrations of microplastics in the gizzards of Virginia waterfowl

by Thomas Bustamante

Faculty Advisor: Dr. Andrew Dolby

Microplastics are defined as plastic fragments that are smaller than 5mm. These particles have become a ubiquitous water pollutant in recent years. While a substantial amount of research on their impacts on marine ecosystems has been conducted, the effect of microplastics on freshwater food webs remains poorly understood. In this study, we assessed the presence and concentrations of microplastic particles in the gizzards of the Canada Goose (Branta canadensis), Ring-necked Duck (Aythya collaris), Long-tailed Duck (Clangula hyemalis), Bufflehead Duck (Bucephala albeola), and Mallard (Anas platyrhynchos) hunted in the Piedmont and Coastal Plain of Virginia. Gizzards were bisected and had their contents removed for analysis. Collected gizzard contents underwent density separation in order to separate plastics from the sediment within gizzards. Isolated particles were then visually inspected under a dissecting microscope. Preliminary results show that with contamination taken into account, 90% of birds sampled contain microplastic fibers in their gizzards. These range in concentration from about 0.08-11.49 fibers/gram of gizzard material. All plastics were secondary fibers, meaning they originated from larger plastics that broke down over time. This provides further evidence that waterfowl not only ingest microplastics, but retain them in their digestive systems. Infrared spectroscopy was done on one fiber; it was determined to be polyethylene. As we move forward, we plan to incorporate chemical digestion and a more efficient chemical analysis in our methods. Further studies will also examine microplastic spatial distributions, as well as microplastics in the intestinal lining and lumen of these birds. This work will be able to help us understand the threat microplastics pose to organisms and ecosystems, as well as help us understand their geographic distributions.

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Exposure effects of thiamethoxam on the viability, growth, and behavior of Physa acuta

by Spencer Saunders

Faculty mentor: Dr. Tyler Frankel

Thiamethoxam is a neonicotinoid insecticide that targets the nicotinic acetylcholine receptors of target organisms. It is used on a wide variety of crops and can be applied in multiple methods including seed coatings, broadcast sprays, or foliar sprays. As thiamethoxam is highly soluble, it easily enters aquatic environments and surface water through run-off events from agricultural fields. Detected environmental concentrations have ranged from the low ng/L range up to 225 ug/L. While the effects of thiamethoxam exposure has been well studied in aquatic vertebrates, few studies have examined their impacts on freshwater invertebrates. As such, this study assessed the impacts of thiamethoxam exposure on the viability, behavior, and shell growth of juvenile freshwater bladder snails (Physa acuta). Adult P. acuta specimens were collected from local waterways in Fredericksburg, VA and bred under laboratory conditions for several generations. Laboratory hatched one-week old juveniles were then exposed to various concentrations of thiamethoxam (0 (EtOH control), 1.56, 3.13, 6.25, 12.5, or 25 ug/L) for two weeks using a static replacement exposure method (100% change every four days). Mortality was assessed every 24 hours, while shell growth and behavior were assessed on day 7 and day 14. Photos of each snail were obtained after one and two weeks and growth was measured using ImageJ (v1.8.0). Behavior was assessed using ToxTrac (v2.83) including average speed, average velocity, total distance traveled, and time spent stationary. While this experiment is still ongoing, we expect to see higher mortality rates and decreased growth concurrent with higher concentrations of thiamethoxam. We also expect to see increases in average speed, average velocity, and total distance traveled with increased exposure concentrations. Our findings will help expand our knowledge on how thiamethoxam impacts multiple physiological endpoints of a novel freshwater invertebrate species.

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The effect of a possible glioblastoma treatment on somatic cells

by Emily Matuczinski and Ashley Parkhurst

Faculty mentor: Dr. Leanna Giancarlo

Glioblastoma multiforme (GBM) is a serious intracranial cancer which maintains a low survival rate due to its aggressive nature and invasive morphology that is resistant to current treatment methods. Recently, superparamagnetic iron-oxide nanoparticles (SPIONs) bound to a TWEAK ligand have been proposed to specifically target glioblastoma cells at their Fn-14 receptor by inducing cellular death of the cancerous cells through the disruption of the membrane when exposed to a magnetic field. While apoptosis in GBM cells was successfully induced in vitro, the effect of the SPION-TWEAK complex on normal somatic cells and the effect of external environments on the SPION biopolymer is currently being evaluated. Specifically, in vitro endothelial cells, a common somatic cell type used in the lining of blood and lymph vessels, were subjected to the SPION-TWEAK complex in the presence and absence of a magnetic field. These cells were visualized via fluorescent microscope to observe if the endothelial cells underwent programmed cell death from the proposed treatment. Results from fluorescence microscopy demonstrate that the SPION-TWEAK complex has no effect on the endothelial cells, maintaining the theory that the conjugated nanoparticles only affect GBM cells. Also, previous studies have shown that the physicochemical properties and integrity of nanoparticles undergo drastic changes in vitro and in vivo, and these changes are attributed to cellular lysosomal degradation. Transmission electron microscopy studies should be conducted to determine whether the biopolymer from the SPION-TWEAK complex is affected by the magnetic field presence, or if the biopolymer is shed by lysosomal degradation. It is crucial to establish the interactions of the nanoparticle complex with benign cells and their magnetic field environment in order to utilize the proposed treatment in vivo so that it does not affect the essential, noncancerous cells in the body.

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A Guide for Creating Great VR Storyboards: Planning to Make Your Virtual Vision a Reality

by Cristina Montemorano

Faculty mentor: Dr. Brenta Blevins

Virtual reality technology has grown in popularity due to increased industry production and innovation. However, the creation of quality content to run on these systems has lagged behind in comparison to the design of the physical equipment required to access virtual environments. How does one go about designing quality VR content? Originally created as instructional material for students in Brenta Blevins’ DGST 301E class, this infographic walks readers through the brainstorming and storyboarding process of creating virtual reality projects. This guide is useful for a wide audience of content creators as they take inspiration from other content mediums, think spatially, and consider the accessibility of their final products.

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Effects of Probiotics on Inflammatory Responses in Neuronal Tissue

by Laura O’Dea, Meredith LeBel, Nicole Haynes

Faculty mentor: Dr. Deborah O’Dell

Alzheimer’s disease (AD) is a neurodegenerative disease that affects more than 40 million people. While the pathophysiology has yet to be fully elucidated, some studies suggest AD associated chronic inflammation is caused by hyperactive microglia that produce pro-inflammatory factors. Probiotics have been shown to have anti-inflammatory properties and may influence neurochemistry via the gut-brain-axis, which controls communication between the intestines and brain, crossing over the blood brain barrier (BBB). A model of the BBB was constructed with a double transwell system to clarify the effects of probiotics on cerebral inflammation. Microglia cells grown in the basolateral chamber were co-cultured with endothelial cells in the upper compartment while an astrocyte monolayer separated the two compartments. Once the system was exposed to human peripheral blood T-cells and combined with histamine (probiotic anti-inflammatory product), formic acid (probiotic inflammatory product), both, or neither, the microglial medium was collected and analyzed for tumor necrosis factor α (TNFα) and interleukin-10 using ELISA. ANOVA and T-Tests were run and showed no significant results, except for the histamine and formic acid combination. In the combination treatment, levels of TNFα were slightly different than the control (p = 0.00006), contrary to what was expected. Under these conditions, probiotics do not reduce inflammation in the brain and thus cannot effectively treat AD patients. However, in the future, more experiments should be conducted with multiple inflammatory and anti-inflammatory molecules as there could be overlapping interactions between several probiotic products that produce advantageous metabolic effects and mitigate elevations in inflammatory responses.

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Deterministic and Stochastic Models for HIV-1 Dynamics

by Amy Creel

Faculty mentor: Dr. Leo Lee

In this research project, I investigated deterministic and stochastic versions of a model for Human Immunodeficiency Virus Type 1 (HIV-1) dynamics. First, the deterministic model is introduced, and numerical techniques are used to obtain an approximate solution to the system. Then, a stochastic model is developed from the deterministic system. Patient data is introduced, and the Monte Carlo Method is used to find an approximate solution to the stochastic system. The results of this project demonstrate the behavior of HIV-1 in an infected patient under the effects of reverse transcriptase and protease inhibitors, and the introduction of randomness to the system of equations allows us to account for the randomness that occurs biologically within the model, thereby making our results more biologically sound.

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Predicting Sexual Satisfaction in Age-Diverse Women

by Meryl Menezes, Anna Higginbotham, Jessica Raiford, and Aidan McClanahan

Faculty mentor: Dr. Jennifer Mailloux

A significant indirect effect of body surveillance (a component of self-objectification) on sexual satisfaction through body shame (the other component of self-objectification), sexual attractiveness, and cognitive distraction during sex was found in a sample of younger women. However, this indirect effect was not found in sample of older women indicating that age, or a correlate of age, may influence the relationships between the variables in our model.

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Carbon Sequestration and Storage Estimates of Landscaped Trees on the University of Mary Washington Campus

by Daniel Milliken

Faculty Mentor: Dr. Alan Griffith

Trees play an important ecological role within the urban environment. They improve public health, provide environmental support and provide aesthetic benefits to cities. To help provide a better understanding on the services that our trees provide, researchers have come up with a way to place economic (monetary) value on these services they provide. Our study will explore the ideas of ecosystem values and answer the following questions: What are the services that the trees located on the University of Mary Washington (UMW) campus provide for the faculty and student population? Specifically, what amount of carbon is removed from the atmosphere by each species of tree through sequestration and storage? This independent research project used the United States Department of Agriculture Forest Service’s software suit, i-Tree Eco, to quantify the ecosystem benefits that the University of Mary Washington’s urban forest conveys to its community.

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Sublethal Effects of Sulfoxaflor Pesticide on Physiology and Behavior of Daphnia magna

by Mary Hoffman

Faculty mentor: Dr. Tyler Frankel

Insect pests are a major concern for large-scale agriculture as a result of increasing insect resistance to pesticides, driving a need for the development of new pesticides. Sulfoxaflor, a sulfoximine pesticide recently approved for use by the USEPA, was developed in order to replace neonicotinoid use and has shown to have high efficacy in the field. It is used in rotation with other pesticides, with environmental introduction caused primarily by wet spray application or agricultural runoff. In insects, sulfoxaflor binds to nicotinic acetylcholine receptors, triggering over-activation that leads to paralysis and death. Preliminary exposure studies have shown neonatal effects and development of liver tumors in rats and mice, and moderate oral toxicity in bobwhite quails and fathead minnows. Little research into the effects of the chemical on aquatic non-target invertebrates has been conducted; as such, this research aims to identify potential physiological and behavioral impacts of sulfoxaflor on adult Daphnia magna at concentrations of 0, 0.1, 1, 10, 100, and 1000 µg/L. Impacts on mobility were determined using top-down recordings and behavioral analysis software ToxTrac (v2.84). Heart rate was analyzed through analysis of minute-long heart recordings to quantify beats per minute. While this research is currently ongoing, it is expected that these treatment levels are sub-lethal at 24 hours, and that exposure to sulfoxaflor at higher concentrations will inhibit heart rate and mobility in adult Daphnia magna. The research aims to help elucidate the potential sub-lethal impacts of sulfoxaflor on non-target aquatic invertebrates.

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Oxygen isotope variability in Crassostrea Virginica shell from the Chesapeake Bay: applications to regional paleoclimate

by Cheyenne Palmo

Faculty mentor: Dr. Pamel Grothe

Future climate predictions in the Chesapeake Bay region suggest unprecedented warming (Cronin et al., 2003) and more intense periods of rainfall (Najjar et al., 2010). In order to quantify present and future changes in climate variability, we need a long baseline of natural climate variability that extends far beyond the instrumental record. Paleoclimate records can be used to help quantify anthropogenic climate change from natural climate variability. However, reconstructing regional climate in an estuary system is challenging, resulting in a lack of pre-instrumental era climate records for the Chesapeake Bay. The Common Eastern Oyster, Crassostrea Virginica, is a promising natural archive to reconstruct natural, or pre-industrial, climate in the Chesapeake Bay region. Stable oxygen isotopes (δ18Oshell) recorded in their calcium carbonate shell are indicators of both changes in temperature and the δ18O of the water (δ18Osw), which is typically a function of salinity. In this study, the δ18Osw and δ18Oshell values were analyzed to understand how the variability in the δ18O of Crassostrea Virginica calcium carbonate shell reflects changes in sea surface temperature and salinity in the Chesapeake Bay in order to validate it as a paleoclimate archive. The oysters were sampled along their banded growth structure, providing yearly resolution for isotopic analysis. We predict that the δ18O of the oyster shell will reflect the same δ18O trends as the water, meaning the shells will precipitate at isotopic equilibrium. Additionally, we predict that salinity, dependent on temperature and precipitation, is the primary driver for changes in δ18O of the shell, whereas increased δ18Oshell values reflect higher salinity values. This work will provide the foundation for understanding the controls between estuarine water and shell geochemistry, with the potential to apply this relationship to regional paleohydrology and paleoclimate reconstruction using fossil Crassostrea Virginica shells.

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