UMD Theses and Dissertations
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New submissions to the thesis/dissertation collections are added automatically as they are received from the Graduate School. Currently, the Graduate School deposits all theses and dissertations from a given semester after the official graduation date. This means that there may be up to a 4 month delay in the appearance of a given thesis/dissertation in DRUM.
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Item Colonial Mentality and the Intersectional Experiences of LGBTQ+ Filipina/x/o Americans(2024) Pease, M Valle; Mohr, Jonathan; Psychology; Digital Repository at the University of Maryland; University of Maryland (College Park, Md.)LGBTQ+ Filipina/x/o Americans have unique experiences due to being at the intersection of racial and sexual/gender marginalization in the United States as well as a complex history of colonialism. The internalization of colonial messages, or colonial mentality, has been linked to mental health in Filipino communities (David et al., 2022). Colonial ideologies include stigmatizing beliefs against gender and sexual diversity and thus have a particular significance for the oppression of LGBTQ+ people. However, no quantitative studies have examined colonial mentality or, more broadly, intersectional experiences in LGBTQ+ Filipino Americans. In a cross-sectional sample of 160 LGBTQ+ Filipino Americans (Mean Age = 26.4), the effect of intersectional discrimination on psychological distress mediated by colonial mentality and identity conflicts was examined, as well as the potential moderating effect of resistance and empowerment against oppression. Analyses found a significant serial mediation such that intersectional discrimination was positively associated with colonial mentality, which was positively associated with conflicts in allegiances, which in turn was positively associated with psychological distress (β = .01, 95% CI: [.0004, .03]). Resistance and empowerment significantly moderated the association between intersectional discrimination and both conflicts in allegiances and psychological distress, such that the impact of discrimination was non-significant for people at high levels of resistance and empowerment. This research has implications for understanding how different histories of oppression impact multiply marginalized groups, which can inform clinical work and efforts to advance decolonization and liberation for marginalized communities.Item WAITING ON “THE HIGHER LAW”: HENRY MASSEY AND THE STRUGGLE AGAINST PHILADELPHIA’S FUGITIVE SLAVE COURT(2023) LaRoche, Matthew David; Bonner, Christopher J; History/Library & Information Systems; Digital Repository at the University of Maryland; University of Maryland (College Park, Md.)Philadelphia’s preeminence as an historical hub of Underground Railroad activity, popularized through the exploits of William Still, is well established. However, a series of archival gaps have virtually erased Philadelphia, and particularly the early years of its fugitive slave court, from the wider historiography of the Fugitive Slave Act of 1850. This work attempts to re-center Philadelphia, as well as its white-led abolitionist organizations and its African American community, in the scholarly discussion over the Act’s origin, intent, and effect. Attempting to overcome archival limitations, this work reconstructs the city’s first fugitive slave court, overseen by Commissioner Edward D. Ingraham from December of 1850 until his death in November of 1854, through the eyes of its participants. Using a close-reading approach, this thesis considers Philadelphia’s resistance to both the Ingraham court and the Act in toto from three perspectives. By comparing the case of Adam Gibson (the first victim of the Ingraham court) to that of Henry Massey, a Maryland freedomseeker and the last person sentenced before Ingraham’s death, this thesis establishes a documentary baseline through which one can trace the court’s evolution across the opening years of the Act’s enforcement. Through recreating the personal and institutional histories of Commissioner Ingraham, the Pennsylvania Abolition Society, and the abolitionist lawyers who represented Gibson, Massey, and other freedomseekers, this thesis provides context to evaluate the legal, social, and religious moves made by the city’s elite in response to the Act’s passage. Finally, by drawing out indications of black organization and agency hidden within the internal records of the Abolition Society itself, this thesis attempts to delineate the practical limits of interracial abolitionist cooperation within Philadelphia at the time. Ultimately, this thesis finds that a combination of geographic pressures and ideological guardrails particular to Philadelphia prevented a stronghold of abolitionist outrage from forming an effective counter to the Act, even while comparable cities (Boston, Syracuse, Harrisburg) developed legal and illegal strategies for shutting down their resident fugitive slave courts.Item SPRAY STRATEGIES AND SELECTION FOR FUNGICIDE RESISTANCE: FENHEXAMID RESISTANCE IN BOTRYTIS CINEREA AS A CASE STUDY(2023) Boushell, Stephen Carl; Hu, Mengjun; Plant Science and Landscape Architecture (PSLA); Digital Repository at the University of Maryland; University of Maryland (College Park, Md.)Fungicide resistance is a limiting factor in sustainable crop production. Despite the wide adoption of general resistance management strategies by growers, the recent rate of resistance development in important fungal pathogens is concerning. In this study, Botrytis cinerea and the high-risk fungicide fenhexamid were used to determine the effects of fungicide dose, tank mixture, and application timing on resistance selection across varied frequencies of resistance via both detached fruit assays and greenhouse trials. The results showed that application of doses lower than the fungicide label dose, mixture with the low-risk fungicide captan, and application post-infection seem to be the most effective management strategies in our experimental settings. In addition, even a small resistant B. cinerea population can lead to a dramatic reduction of disease control efficacy. Our findings were largely consistent with the recent modeling studies which favored the use of the lowest possible fungicide dose for improved resistance management.Item ENGENDERED EXPERIENCES OF FREEDOM: LIBERATED AFRICAN WOMEN IN RIO DE JANEIRO, 1834-1864(2020) Nadalini Mendes, Ana Paula; Williams, Daryle; History; Digital Repository at the University of Maryland; University of Maryland (College Park, Md.)“Engendered Experiences of Freedom: Liberated African Women in Rio de Janeiro (1834-1864)” investigates how gender differences in daily lives of liberated African women in Brazil shaped the way they experienced freedom. This research argues that gendered-based differences influenced their experiences of freedom in its various contexts, including their relationship to labor, their struggles for emancipation, and their approach to legal system. Moreover, this thesis follows the lives of particular liberated African women through their process of petitioning for emancipation twenty years after they got to Brazil. Although the first half of the nineteenth century was marked by legal efforts to bar importation of slaves from Africa to Brazil, many slave ships entered Brazilian ports successfully. The Rio da Prata, however, was an exception. In November 1834, the British marine intercepted the vessel, that was halfway between Africa and South America. The Anglo-Brazilian Mixed Commission judged the case as a transgression of the Treaty of 1826, that forbade Brazil to participate in the slave trade, condemned the vessel to be a good-prize and liberated more than two hundred Africans. These Africans worked for private houses and public works in a probation system for at least 20 years when the decree 1303 of 1853 allowed them to access the legal system and request their final emancipation. This process lasted for ten years, when in 1864 the Brazilian government declared emancipated all liberated Africans This thesis intervenes in debates about bondage and resistance by considering liberated Africans women inside the context of slavery in Brazil. It argues that these women had a particular way of fighting for freedom, due, first, to their own capacity of resistance, second to their conditions of labor, and, third, to specificities of the Brazilian set of laws. From legal petitions of emancipation, police records, guardians’ declarations, and newspapers advertisements the chapters follow lives of liberated African women from the Rio da Prata to show how they experienced freedom.Item Change Is Sound: Resistance and Activism in Queer Latinx Punk Rock(2019) Dowman, Sarah; Long, Ryan; Spanish Language and Literature; Digital Repository at the University of Maryland; University of Maryland (College Park, Md.)Change Is Sound explores the roles punk ethos, discourses, and collectivism play in creating resistant practices within queer US Latinx punk communities since the 1970s. My research engages critically with the fields of contemporary Latinx cultural studies and hemispheric queer studies to elucidate new perspectives on the emerging critical category of Latinx, to challenge stagnant narratives of resistance and activism in queer communities of color in the US, and to provide a framework for how resistant practices are being defined and constructed in the present. Furthermore, my study decenters the “white riot” narrative of punk that excludes and erases diversity by categorizing the subculture as a straight, white, male, suburban, middle-class, youth phenomenon. My study achieves this decentering by focusing on intersectional, transnational, and transgenerational subjectivities represented by the contributions of queer Latinx punk artists. By diversifying the perspectives and experiences represented and highlighting how these artists forge connections to larger histories of resistant practices in queer communities of color in the US and transnationally, I demonstrate how underrepresented populations expand punk’s emancipatory potential. Specifically, my research shows how resistant practices such as performative and activist interventions and the creation of online collective revisionist writings present a foundation from which queer Latinx and other marginalized communities negotiate power, hegemony, and resistance within the contemporary context of precarity and oppression under neoliberalism and capitalist globalization.Item Fate of antimicrobials and nutrients in dairy manure management systems(2018) Schueler, Jenna E; Lansing, Stephanie; Environmental Science and Technology; Digital Repository at the University of Maryland; University of Maryland (College Park, Md.)Anaerobic digestion (AD) and composting manure management strategies were explored at the field scale to monitor antimicrobial degradation, nutrient transformations, and optimize mitigation of these pollutants in manure fertilizer to decrease their entry to waterways. Removal of antimicrobials and antimicrobial resistance genes (ARGs) were explored at the bench scale, where AD degraded >85% of antimicrobials. At the field-scale, antimicrobials were not consistently removed, persisting in concentrations up to 34,000 ng/g DW in the AD effluent. The tetM genes were reduced during bench-scale AD suggesting that AD could be an effective treatment for removing tetracycline ARGs from manure. The 100% reduction of sulfadimethoxine antimicrobials during AD did not correspond with Sul1 reduction, illustrating differences in antimicrobial versus gene reductions during manure treatment. Antimicrobials did not degrade significantly during field scale composting, likely due to a shortened composting period (33-days). The field-scale results illuminate limitations of tracking antimicrobials in complex treatment systems.Item War and Resistance: The Philippines 1942-1944(2018) Morningstar, James; Sumida, Jon T; History; Digital Repository at the University of Maryland; University of Maryland (College Park, Md.)ABSTRACT Title of Dissertation: WAR AND RESISTANCE: THE PHILIPPINES, 1942-1944 James Kelly Morningstar, Doctor of History, 2018 Dissertation directed by: Professor Jon T. Sumida, History Department What happened in the Philippine Islands between the surrender of Allied forces in May 1942 and MacArthur’s return in October 1944? Existing historiography is fragmentary and incomplete. Memoirs suffer from limited points of view and personal biases. No academic study has examined the Filipino resistance with a critical and interdisciplinary approach. No comprehensive narrative has yet captured the fighting by 260,000 guerrillas in 277 units across the archipelago. This dissertation begins with the political, economic, social and cultural history of Philippine guerrilla warfare. The diverse Islands connected only through kinship networks. The Americans reluctantly held the Islands against rising Japanese imperial interests and Filipino desires for independence and social justice. World War II revealed the inadequacy of MacArthur’s plans to defend the Islands. The General tepidly prepared for guerrilla operations while Filipinos spontaneously rose in armed resistance. After his departure, the chaotic mix of guerrilla groups were left on their own to battle the Japanese and each other. While guerrilla leaders vied for local power, several obtained radios to contact MacArthur and his headquarters sent submarine-delivered agents with supplies and radios that tie these groups into a united framework. MacArthur’s promise to return kept the resistance alive and dependent on the United States. The repercussions for social revolution would be fatal but the Filipinos’ shared sacrifice revitalized national consciousness and created a sense of deserved nationhood. The guerrillas played a key role in enabling MacArthur’s return. Their legacy shaped Philippine national identity and the political contest between exiled officials, collaborationists, and the members of resistance. The research presented in this dissertation crosses military, cultural, social, political, economic and diplomatic fields. It gives voice to the Filipino, Japanese, and American actors and shows how their actions and stories are not only interrelated but interdependent. In this way it hopes to reach several audiences at once. For the military student, this case study reveals the multiple and particular roots of guerrilla warfare. For others, it reveals the fundamental role of military action in important social and cultural developments. Finally, and most essentially, it tells a fascinating story that has been long ignored.Item DATA DRIVEN APPROACHES TO IDENTIFY DETERMINANTS OF HEART DISEASES AND CANCER RESISTANCE(2016) Sahu, Avinash Das; Hannenhalli, Sridhar; Ruppin, Eytan; Computer Science; Digital Repository at the University of Maryland; University of Maryland (College Park, Md.)Cancer and cardio-vascular diseases are the leading causes of death world-wide. Caused by systemic genetic and molecular disruptions in cells, these disorders are the manifestation of profound disturbance of normal cellular homeostasis. People suffering or at high risk for these disorders need early diagnosis and personalized therapeutic intervention. Successful implementation of such clinical measures can significantly improve global health. However, development of effective therapies is hindered by the challenges in identifying genetic and molecular determinants of the onset of diseases; and in cases where therapies already exist, the main challenge is to identify molecular determinants that drive resistance to the therapies. Due to the progress in sequencing technologies, the access to a large genome-wide biological data is now extended far beyond few experimental labs to the global research community. The unprecedented availability of the data has revolutionized the capabilities of computational researchers, enabling them to collaboratively address the long standing problems from many different perspectives. Likewise, this thesis tackles the two main public health related challenges using data driven approaches. Numerous association studies have been proposed to identify genomic variants that determine disease. However, their clinical utility remains limited due to their inability to distinguish causal variants from associated variants. In the presented thesis, we first propose a simple scheme that improves association studies in supervised fashion and has shown its applicability in identifying genomic regulatory variants associated with hypertension. Next, we propose a coupled Bayesian regression approach -- eQTeL, which leverages epigenetic data to estimate regulatory and gene interaction potential, and identifies combinations of regulatory genomic variants that explain the gene expression variance. On human heart data, eQTeL not only explains a significantly greater proportion of expression variance in samples, but also predicts gene expression more accurately than other methods. We demonstrate that eQTeL accurately detects causal regulatory SNPs by simulation, particularly those with small effect sizes. Using various functional data, we show that SNPs detected by eQTeL are enriched for allele-specific protein binding and histone modifications, which potentially disrupt binding of core cardiac transcription factors and are spatially proximal to their target. eQTeL SNPs capture a substantial proportion of genetic determinants of expression variance and we estimate that 58% of these SNPs are putatively causal. The challenge of identifying molecular determinants of cancer resistance so far could only be dealt with labor intensive and costly experimental studies, and in case of experimental drugs such studies are infeasible. Here we take a fundamentally different data driven approach to understand the evolving landscape of emerging resistance. We introduce a novel class of genetic interactions termed synthetic rescues (SR) in cancer, which denotes a functional interaction between two genes where a change in the activity of one vulnerable gene (which may be a target of a cancer drug) is lethal, but subsequently altered activity of its partner rescuer gene restores cell viability. Next we describe a comprehensive computational framework --termed INCISOR-- for identifying SR underlying cancer resistance. Applying INCISOR to mine The Cancer Genome Atlas (TCGA), a large collection of cancer patient data, we identified the first pan-cancer SR networks, composed of interactions common to many cancer types. We experimentally test and validate a subset of these interactions involving the master regulator gene mTOR. We find that rescuer genes become increasingly activated as breast cancer progresses, testifying to pervasive ongoing rescue processes. We show that SRs can be utilized to successfully predict patients' survival and response to the majority of current cancer drugs, and importantly, for predicting the emergence of drug resistance from the initial tumor biopsy. Our analysis suggests a potential new strategy for enhancing the effectiveness of existing cancer therapies by targeting their rescuer genes to counteract resistance. The thesis provides statistical frameworks that can harness ever increasing high throughput genomic data to address challenges in determining the molecular underpinnings of hypertension, cardiovascular disease and cancer resistance. We discover novel molecular mechanistic insights that will advance the progress in early disease prevention and personalized therapeutics. Our analyses sheds light on the fundamental biological understanding of gene regulation and interaction, and opens up exciting avenues of translational applications in risk prediction and therapeutics.Item Development of methods to test drug sensitivity of fish pathogenic Flavobacterium columnare and drug sensitivity thresholds for F. columnare to the antimicrobial florfenicol.(2015) Gieseker, Charles Michael; Woods III, Lewis C.; Marine-Estuarine-Environmental Sciences; Digital Repository at the University of Maryland; University of Maryland (College Park, Md.)Antimicrobial drugs play a key role in managing the health of fish in aquaculture. However, public health concerns about antimicrobial resistance--the ability of microorganisms to resist standard antimicrobial treatments--include the potential for antimicrobial use in aquaculture to select for resistant bacteria in and around fish farms. Recent approval of two antimicrobial drugs to treat farmed freshwater fish with infections caused by the aquatic bacteria Flavobacterium columnare and F. psychrophilum created an important need for research to monitor these bacteria for changes in antimicrobial susceptibility and to decide when the antimicrobials should be used. Therefore three studies were conducted. The initial study optimized methods for broth microdilution testing F. columnare and F. psychrophilum and conducted a multi-laboratory standardization trial that set quality control parameters for nine antimicrobials commonly used in aquaculture, thus creating the first standardized testing method. In the second study, we constructed frequency distributions using minimal inhibitory concentrations determined from testing 134 F. columnare with the standardized method. Analysis of the distributions determined the drug concentration--called an epidemiological cutoff value (ECV)--which separated the wild type isolates with no acquired or selected resistance from the non-wild type isolates. The ECV indicated 22 of 134 isolates had decreased their susceptibility to at least 1 antimicrobial. In addition, we developed a laboratory disease model with juvenile channel catfish, Ictalurus punctatus. We compared the virulence of three F. columnare isolates with wild type or three isolates with non-wild type florfenicol susceptibility using the model. We found that five isolates had similar high level virulence and were not affected by differences in florfenicol susceptibility. Finally, we studied if decreased non-wild type florfenicol susceptibility affected the ability of the approved florfenicol treatment to control F. columnare infections. The approved treatment significantly reduced catfish mortality following exposure to an isolate with typical wild type florfenicol susceptibility but mortality was not reduced following exposure to an isolate with non-wild type susceptibility. Taken together, these studies provide methods and research needed to monitor F. columnare for changes in antimicrobial susceptibility and to rationally use florfenicol to control F. columnare infections.Item A STRUCTURAL MODEL OF INSECT CONTROL DECISIONS: ROOTWORM RESISTANCE IN US CORN FIELDS(2014) Wechsler, Seth James; Lichtenberg, Erik; Agricultural and Resource Economics; Digital Repository at the University of Maryland; University of Maryland (College Park, Md.)Recent evidence from field tests and laboratory studies suggest that rootworms are adapting to the toxins produced by genetically modified, insect resistant (Bt) seeds. Given that rootworms cause over 1 billion dollars in yield losses and treatment costs per year, finding larger scale evidence of resistance could have important policy ramifications. This dissertation analyses corn farmers' insect control decisions in an effort to determine whether rootworms have adapted to Bt seeds. Chapter 1 provides a broad overview of the literature on genetically engineered (GE) seeds. It strives to correct many commonly held misperceptions about genetically modified seeds. Chapter 2 provides a detailed description of the economic literature on pesticide productivity and GE seed use. It compares structural to reduced form models, and discusses how previous studies have accounted for endogeniety. Chapter 3 develops a two stage, theoretical model of corn farmers' insect control decisions. This model is used to derive a non-linear, soil insecticide demand function. Chapter 4 presents the dissertation's empirical approach. First, it describes the data used in the analysis. Next, it discusses how to estimate the soil insecticide demand function derived in Chapter 3. Finally, it discusses how the parameters of the structural model can be used to determine how: a) Bt adoption affects yields, b) Bt adoption affects insecticide use, and c) whether the effectiveness of Bt seeds has changed over time. Chapter 5 provides the study's results. These results indicate that using rootworm resistant seeds would have decreased soil insecticide use by 70% in 2005 and 84% in 2010. Bt adoption would have increased yields by .6 percentage points (1.02 bushels/acre) in 2005 and .1 percentage points (.2 bushels per acre) in 2010. Alarmingly, the evidence suggests that rootworm resistant seeds were less effective in 2010 than in 2005, and less effective on farms where selective pressure was high than on farms where selective pressure was low. In other words, the results of this study support the hypothesis that rootworms are adapting to Bt seed use. Chapter 6 concludes.