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Helly-Type Theorems on Support Lines for Families of Congruent Disks in the Plane
Get PDFIn this dissertation, we consider the problem to determine Helly-type numbers for support lines of nonoverlapping families of congruent disks in the plane. This problem, originally posed by R. Dawson for the case of disjoint families of convex bodies and by V. Soltan for the case of disjoint families of unit disks, has been recently solved. This research generalizes to the case of non-overlapping families of congruent disks. An essential part of the argument is based on the study of "critical" families of congruent disks
"Fundamental Laws of the Land": Christopher McPherson's Struggle to Achieve Equality, Inclusion, and Civil Discourse in Post- Revolutionary Virginia
Get PDFIn June 1810, the Richmond City Council passed the "Ordinance for Regulating Waggons, Drays, and Carts." It stipulated that as of January 1, 1811, free Black Americans could no longer use or own carriages in the city.1 Within weeks, Christopher McPherson, son of a Scottish merchant and an enslaved woman, responded to the ordinance with a letter expressing his "great astonishment."2 He elaborated, writing the decision had "led me to reflect on the whole tenor of my life and the services I had rendered my Native Country."3 McPherson later launched an ardent campaign to repeal the ordinance
Evaluating the Impact of Land Cover and Climate Change on Biodiversity at Local, Regional, and Global Scales
Get PDFHuman activity is driving land cover change and climate change, threatening global biodiversity. Most research on this topic takes an individualistic approach, evaluating how one species or population responds to a disturbed environment. However, ecosystems are considerably more complex, and changes to one species has implications for other species in the same ecosystem. Therefore, the purpose of this dissertation is to evaluate the impacts of land cover change, specifically forest loss and forest fragmentation, and climate change, on biodiversity. The goal is to evaluate the impacts on complex species interactions and widespread biodiversity loss at local, regional, and global scales. This research focuses primarily within the Amazon basin, as it is the largest and most biodiverse tropical forest in the world
AN APPLIED ECONOMIC ANALYSIS OF PERCEPTIONS IN THE MARKETPLACE
Get PDFThis dissertation centers around issues of expectations theory and how expectations may serve as informal and formal constraints in the decision-making process. I examine three key points: the Big Lick phenomena in the Tennessee Walking Horse show world, Wagnerian expectations concerning adversities facing minority populations, and a more theoretical and abstract approach to expectations with the role animal spirits play in the marketplace. This dissertation finds that, whether informal or formal, expectations play a critical role in an acting agent's decision matrix, both in private and public market arrangements
ASSESSMENT OF COMPLEX SKILLS IN COLLABORATIVE, ILL-STRUCTURED GAMES
Get PDFThis work is embargoed by the author and will not be publicly available until December 2025.Games offer a promising avenue for assessing authentic and complex learning that is increasingly sought in higher education. Collaborative, ill-structured games that simulate real-world problems are not compatible with traditional psychometric measurement approaches. There is no established framework for assessing collaborative, ill-structured games. In fact, assessment practice of games- and simulation-based learning more broadly is nascent. In spite of daunting challenges for valid and meaningful assessment of such activities, professional military education (PME) is rapidly expanding collaborative, ill-structured gaming in response to senior-level directives. PME’s concrete manifestation of the broader theoretical and methodological challenges of games-based assessment seen in higher education presents a unique opportunity to develop an assessment framework that can inform practice. Using an evidence-centered design (ECD) approach, this dissertation presents three studies which develop a validity argument, propose the Comprehensive Learning Assessment for Wargames (CLAW) framework, and then examine the relevance of, and evidentiary expectations for, that framework for assessing collaborative, ill-structured wargames in praxis. In toto, the CLAW provides a baseline for game designers to clearly specify their assessment claim(s) and identify the key evidence that they should consider to substantiate the interpretation and use of assessment evidence for their desired purpose(s). Although situated within PME, the framework has broader relevance as a model for assessment of collaborative, ill-structured games in other disciplines that are confronting similar challenges.2025-12-1
Regulatory Effects of Iron and Quorum Sensing on Virulence Factor Expression in Vibrio vulnificus
Get PDFAs antibiotic resistance in Vibrio vulnificus becomes more abundant, there is a greater need to identify new therapeutic measures to combat infections. To do so, it is important to understand which environmental factors contribute to the virulence of the organism. Such factors include cell density and iron prevalence. This review evaluated studies that explored how genetic and protein factors related to iron prevalence and cell density impact the virulence of V. vulnificus through iron-dependent gene expression and quorum sensing mechanisms respectively. Changes in virulence were determined through the expression of virulence factors such as proteases and hemolysins. It was ultimately observed that increases in quorum sensing promoted the expression of proteases VVP and VvpE. Increased quorum sensing also seemed to repress the expression of the hemolysin VVH. Meanwhile, the enhanced presence of iron stimulated VvpE production and transcriptionally repressed hemolysin expression. These systems of iron-dependent gene expression and quorum sensing also seemed to play roles in regulating each other, with quorum sensing being more heavily regulated by iron prevalence. These findings shed light on mechanisms by which iron prevalence and quorum sensing impact the virulence of V. vulnificus. Such knowledge may be used to identify potential pharmaceutical targets to ease virulence in cases of acute vibriosis and reduce the use of conventional antibioti
Comparative Analysis of Flexible Transducers
Get PDFIn 2020 the private sector reported 247,620 musculoskeletal injuries because of day-to-day activities [1]. Musculoskeletal Injuries are a result of day-to-day activities and rarely evaluated in a timely manner. To understand musculoskeletal injuries, there lacks a clear, consistent, and repeatable method for capturing muscle function during dynamic tasks. Current methods of tracking and understanding muscle function include dynamometry, motion capture, and surface electromyography (sEMG) [2]. However, these methods are not ideal for examining musculoskeletal injuries for dynamic tasks.
To address the shortcomings of issues in tracking muscle function during dynamic tasks to better understand musculoskeletal injuries, the focus of this work will revolve around ultrasound transducers specifically, the methods to design, build, test, and compare with other flexible transducers. Characterizing methods include examining the signal frequency components, acoustic pressure produced by the transducer, and the imaging ability of the transducer. This thesis goes over the background and need for flexible transducers, development and analysis of a flexible transducer, and a comparative analysis against other flexible transducers
Biomonitoring for Per- and Polyfluoroalkyl Substances Using the Invasive Asian Clam, Corbicula fluminea
Get PDFConsidered contaminants of emerging concern, per- and polyfluoroalkyl substances (PFAS) are a class of toxic, manufactured chemicals from commercial and consumer products found in the environment, drinking water, and wildlife. This dissertation (1) explored the use of PFAS in munitions in the Russia-Ukraine conflict, (2) showed increasing use of freshwater bivalves as bioindicators for chemicals of concern, but highlighted opportunities to incorporate these organisms into field studies and long-term monitoring programs globally, and (3) confirmed the utility of the low-cost, replicable biomonitoring methods using the Asian clam to detect and quantify PFAS in freshwater ecosystems
Mammal Reactions to Novel Objects in Their Environment
Get PDFThe way in which mammals respond to novel objects can inform experts and managers about how urbanization is impacting species. The behaviors of three common North American mammal species with great behavioral adaptability, raccoons (Procyon lotor); red foxes (Vulpes vulpes); and white-tailed deer (Odocoileus virginianus), were observed using remotely triggered wildlife cameras and novel objects. The amount of time an individual spent within view of the camera, the number of behaviors exhibited, and the time it took an individual to approach novel objects and control sites were analyzed as a function of canopy cover, impervious cover, and human population density. Correlations between canopy cover, impervious cover, and population density and response variables, and the direction of effects differed between species, but trends emerged among similar taxa (carnivores). This study can inform plans and protocols to mitigate human-wildlife conflicts while considering how different species respond to urbanization
Contested LGBTIQ+ Activism, Complex Identities, and Entrenched Norms: Investigating the Normative Effects of EuroPride 2022 in Serbia
Get PDFA global proliferation of local and transnational movements for the rights of lesbian, gay, bisexual, transgender, intersex, and queer (LGBTIQ+) people in the 21st century has faced resistance in many contexts from opponents who frame LGBTIQ+ rights as a threat to national values, norms, and identities. The present mixed-methods dissertation examines whether and how such highly contested transnational LGBTIQ+ activism can influence social norms on gay and lesbian rights. The dissertation addresses this question through three empirical studies focused on the case of Serbia, where pressure from the European Union (EU) to improve respect for LGBTIQ+ rights, including by protecting space for LGBTIQ+ activism, has been vehemently opposed by some domestic groups. Study 1 (N = 2,043) provides a foundational understanding of gay and lesbian rights norms in Serbia by analyzing a nationally representative dataset and identifying factors associated with rights support (European identity, acceptance of diversity, and location in Belgrade) and opposition (Serbian national identity, traditionalism, religiosity). In addition to validating the findings from Study 1, Study 2 (N = 500) applies more complex analytical techniques to analyze how gay and lesbian rights norms vary across groups with different latent combinations of social identity. The study found that a group with the highest levels of Serbian national identity and lowest levels of European and EU identities expressed gay and lesbian rights attitudes and behavioral intentions that were more aligned with perceptions of Serbian norms (i.e., perceptions of other people’s attitudes in Serbia) and less aligned with their perceptions of norms in Europe. Conversely, a group with the highest levels of European and EU identities expressed attitudes and behavioral intentions that were less aligned with their perceptions of Serbian norms. Building upon the first two studies, Study 3 (N = 854) used data from a two-wave panel study with a sample Belgrade, Serbia residents to evaluate the effects of EuroPride, a highly contested pan-European LGBTIQ+ Pride event held in Serbia in 2022, on norm perceptions, personal attitudes, and behavioral intentions on gay and lesbian rights. Study 3 found that EuroPride had inconsistent social normative effects which did not vary across the latent identity-based groups identified in Study 2. The dissertation grapples with possible explanations for the event’s null effects, including 1) conflicting normative signals from national and religious leaders, 2) delegitimization of Pride activism as a foreign-driven political exercise, and 3) attitudinal saturation following more than a decade of annual Pride parades in Serbia. Drawing upon the three studies, the dissertation discusses interdisciplinary theoretical implications and recommendations for policymakers and practitioners supporting transnational LGBTIQ+ activism. Finally, limitations and areas for future research on pro-LGBTIQ+ social change are discussed