Theses and Dissertations from UMD
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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 give thesis/dissertation in DRUM
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Item Essays on Institutions, Governance and Economic Growth(2024) Batra, Kartikeya; Galiani, Sebastian; Economics; Digital Repository at the University of Maryland; University of Maryland (College Park, Md.)Economic development and growth are impacted by several factors. Among these, existing social institutions, and quality of governance are important determinants. These factors become especially relevant in the context of low and middle-income countries. Such nations are home to a large share of the world’s population, and aspire to grow their economies at high rates. Understanding constraints to their socio-economic development and prescribing policy solutions is, therefore, an important area of research. In the three chapters of this dissertation, I explore three different issues that impact social institutions and governance, which, in turn, impact socio-economic development. I do so in the context of India, which is home to approximately 20% of the world’s total population. In the first chapter, I explore whether historical land policies impact long-run socio-economic outcomes, including the persistent institution of the caste system and stereotypes associated with it. I find that lower land concentration does lead to improved socio-economic outcomes, especially for the socially marginalized landless communities. In the second chapter, I test whether enhanced state capacity by means of better public infrastructure improves the performance ofbureaucrats in rural India. I find that better roads lead to better bureaucratic performance, possibly due to improved monitoring by higher officials whose mobility is positively impacted. Finally, in the third chapter, I examine whether the size of a political party impacts its decisions to field wealthy candidates. I find that a smaller political party is likely to field a wealthier candidate than a bigger political party, possibly due to fewer avenues to mobilize resources. This is important, for the wealth profile of a candidate, in turn, has the potential to impact governance outcomes in their area. The three chapters are aimed at understanding causal relationships pertaining to important questions in the context of India’s society, political economy and economic development. My results provide novel contributions to relevant strands literature, and also allow me to provide relevant policy prescriptions.Item Examining the co-development of episodic memory and hippocampal subfields – A longitudinal study(2020) Canada, Kelsey Leigh; Riggins, Tracy; Psychology; Digital Repository at the University of Maryland; University of Maryland (College Park, Md.)Episodic memory is a cornerstone ability that allows one to recall past events and the context in which they occur. Many different tasks have been used to assess the development of episodic memory during early childhood. Previous longitudinal work on individual tasks has noted accelerated changes from approximately 5 to 7 years, suggesting non-linear changes in memory ability during early childhood. However, the extent to which tasks relate to one another and are indicative of the latent construct of episodic memory is not known. Further, improvements in memory are thought to relate to underlying changes occurring in the functionally distinct subfields of the hippocampus (i.e., CA2-4/dentate gyrus (DG), CA1, and Subiculum) during this developmental period. This study examined changes in episodic memory ability, hippocampal subfield volume, and the relation between changes in episodic memory and volume of hippocampal subfields during early childhood (4 to 8 years) using longitudinal data and a structural equation modeling framework. Results suggest that episodic memory ability improves substantially during this period, with consistent improvements between 4 to 8 years. Further, there are robust increases in subiculum, CA1, and CA2-4/DG volume between 5 to 6 years of age. Finally, within this sample, there were relations between the development of hippocampal subfields and improvements on a single source memory task commonly used to assess episodic memory. Interestingly, this relation was most robust between subiculum and source memory. Overall, these results highlight the ability to use laboratory tasks to characterize developmental changes in episodic memory, highlight 5- to 6-years as a period of developmental change in hippocampal subfields, and further support a role of the hippocampus in supporting episodic memory.Item SPATIO-TEMPORAL ANALYSIS OF PHOTOTROPISM IN ARABIDOPSIS SEEDLINGS(2019) Pritchard, Candace; Murphy, Angus S; Plant Science and Landscape Architecture (PSLA); Digital Repository at the University of Maryland; University of Maryland (College Park, Md.)Optimization of light capture during seedling development is a major determinant of plant fitness. As seedlings emerge from the soil, the processes of photomorphogenesis and phototropism optimize deployment of structures that capture light for photosynthesis. Photomorphogenesis produces hypocotyl thickening, cotyledon expansion, and chloroplast maturation. Concurrent phototropic responses initiated by blue light position the expanding cotyledons to maximize photosynthesis. The mechanisms underlying both processes have been explored for more than 140 years, but are still not fully understood. This dissertation seeks to provide a better understanding of phototropism by exploring the timing and localization of the constituent mechanisms downstream of the well-characterized perception of blue light by the PHOTOTROPIN photoreceptors. The experiments described herein characterize temporally and spatially distinct processes involved in asymmetric auxin accumulations that lead to differential hypocotyl elongation. To better identify the link between early perception and later auxin transport and elongation events, an open-air system was used to remove seedling hindrance and provide better spatio-temporal resolution. These experiments confirmed the more rapid bending conferred by loss of the ATP Binding Cassette class B (ABCB) 19 auxin efflux transporter and loss of differential elongation in the mid hypocotyl elongation zone in higher order pinformed mutants. However, apart from the enhancement of phototropic bending observed in abcb19 and pin4 mutants, no auxin transport mutants tested showed alterations in early phototropic responses, and no mutant exhibited a delay in the onset of phototropic bending. Recently identified CBC1 and CBC2 (CONVERGENCE OF BLUE LIGHT (BL) AND CO2 1/2) have been shown to act in downstream signaling during phot1-mediated regulation of stomatal conductance. Similarly, during phototropism cbc1cbc2 double mutants show early defects in phot1-mediated phototropism. Further, CBC1 and CBC2 have been shown to regulate S-type anion channels. Analysis of S-type anion channel mutants also reveals defects in early bending responses. These results point to blue light-dependent regulation of anion channel activity having an important role during the earliest stages of phototropism.Item Subplate neurons and their role in the functional maturation of the brain(2016) Sheikh, Aminah; Kanold, Patrick O; Biology; Digital Repository at the University of Maryland; University of Maryland (College Park, Md.)Normal brain development is crucial for the proper maturation of neural circuits and cognitive functioning. White matter brain injury during development results in disruption of normal brain maturation and consequently increases risk of developing disorders such as epilepsy and cerebral palsy. Crucial for the proper development of thalamocortical circuits are a transient population of neurons in the developing subcortical white matter of the brain referred to as subplate neurons (SPNs). SPNs are among the first cortical neurons to be born and are necessary for normal functional development of the cerebral cortex. This dissertation begins by studying the effect of SPN removal in the neonatal rat somatosensory cortex (S1). After subplate ablation in the S1 barrel region, we find that removal of SPNs prevents the development of the barrel field in L4, and in vitro recordings reveal that thalamocortical inputs to layer 4 neurons are weak. This dissertation then progresses to investigating the effects of a more clinically relevant and common brain injury among humans, neonatal hypoxia-ischemia (HI), which causes brain damage specific to different brain structures over development. In the preterm human, HI results in damage to subcortical developing white matter, referred to as periventricular leukomalacia (PVL). From other studies we know that HI can damage SPNs however, it is unclear how HI and its differing severities alters SPN circuits. This dissertation uses a rat model of HI in which either mild or moderate HI was induced at postnatal day (P)1. To investigate the functional synaptic connectivity changes of SPNs and layer 4 neurons in both injury categories, this dissertation also uses laser-scanning photostimulation (LSPS) combined with whole-cell patch clamp recordings in acute thalamocortical slices of rat A1 over development. Our results suggest that SPNs are uniquely susceptible to HI and that HI causes a rearrangement of SPN circuits. This leads to abnormal cortical function observed after HI. Results from these studies help fill in crucial gaps in the understanding of not only how important SPNs are in the proper development of multiple sensory regions, but also how vulnerable they are to hypoxic-ischemic brain injury.Item Development and plasticity of the functional laminar mesoscale organization of the primary auditory cortex(2016) Solarana, Krystyna; Kanold, Patrick O; Biology; Digital Repository at the University of Maryland; University of Maryland (College Park, Md.)Early sensory experience is fundamental for proper structural and functional organization of the brain. A brain region that particularly relies on sensory input during a critical period of development is the primary auditory cortex (A1). The functional architecture of A1 in adult mammals has been widely studied on a macroscale and single-cell level, and it is evident that this sensory area is characterized by a tonotopic gradient of frequency preference and that individual auditory neurons are tuned to complex features of acoustic stimuli. However, the development of microcircuits within A1 and how experience shapes this mesoscale organization during different plasticity windows is not known. The work in this dissertation uses in vivo two-photon calcium imaging in mice to investigate how the population dynamics of auditory neurons within thalamorecipient layer 4 and supragranular layers 2/3 change over development – from before ear opening, through the critical period for auditory spectral tuning, and on to mature adult circuitry. Furthermore, this dissertation explores how brief visual deprivation has the power to initiate compensatory, cross-modal plasticity mechanisms and restructure network circuitry in the adult auditory cortex, after the critical period for developmental plasticity has closed. Results from these studies fill crucial gaps in our understanding of experience-dependent cortical circuit development and refinement by showing that the spatial representation of sound frequency is shaped by sensory experience, teasing apart the underlying laminar-specific differences in microcircuitry changes, and indicating an overall dissociation of plasticity of single-cell, mesoscale, and macroscale network properties.Item Shaping the Dicot Fruit: Molecular and Genomic Approaches to Fruit Development(2016) Hawkins, Charles; Liu, Zhongchi; Cell Biology & Molecular Genetics; Digital Repository at the University of Maryland; University of Maryland (College Park, Md.)The fruit is one of the most complex and important structures produced by flowering plants, and understanding the development and maturation process of fruits in different angiosperm species with diverse fruit structures is of immense interest. In the work presented here, molecular genetics and genomic analysis are used to explore the processes that form the fruit in two species: The model organism Arabidopsis and the diploid strawberry Fragaria vesca. One important basic question concerns the molecular genetic basis of fruit patterning. A long-standing model of Arabidopsis fruit (the gynoecium) patterning holds that auxin produced at the apex diffuses downward, forming a gradient that provides apical-basal positional information to specify different tissue types along the gynoecium’s length. The proposed gradient, however, has never been observed and the model appears inconsistent with a number of observations. I present a new, alternative model, wherein auxin acts to establish the adaxial-abaxial domains of the carpel primordia, which then ensures proper development of the final gynoecium. A second project utilizes genomics to identify genes that regulate fruit color by analyzing the genome sequences of Fragaria vesca, a species of wild strawberry. Shared and distinct SNPs among three F. vesca accessions were identified, providing a foundation for locating candidate mutations underlying phenotypic variations among different F. vesca accessions. Through systematic analysis of relevant SNP variants, a candidate SNP in FveMYB10 was identified that may underlie the fruit color in the yellow-fruited accessions, which was subsequently confirmed by functional assays. Our lab has previously generated extensive RNA-sequencing data that depict genome-scale gene expression profiles in F. vesca fruit and flower tissues at different developmental stages. To enhance the accessibility of this dataset, the web-based eFP software was adapted for this dataset, allowing visualization of gene expression in any tissues by user-initiated queries. Together, this thesis work proposes a well-supported new model of fruit patterning in Arabidopsis and provides further resources for F. vesca, including genome-wide variant lists and the ability to visualize gene expression. This work will facilitate future work linking traits of economic importance to specific genes and gaining novel insights into fruit patterning and development.Item Development Begins at Home: Women and the Domestic Economy in Brazil, 1945-1975(2016) Moura, Shawn; Williams, Daryle; History; Digital Repository at the University of Maryland; University of Maryland (College Park, Md.)A number of historians of twentieth-century Latin America have identified ways that national labor laws, civil codes, social welfare programs, and business practices contributed to a gendered division of society that subordinated women to men in national economic development, household management, and familial relations. Few scholars, however, have critically explored women's roles as consumers and housewives in these intertwined realms. This work examines the Brazilian case after the Second World War, arguing that economic policies and business practices associated with “developmentalism” [Portuguese: desenvolvimentismo] created openings for women to engage in debates about national progress and transnational standards of modernity. While acknowledging that an asymmetry of gender relations persisted, the study demonstrates that urban women expanded their agency in this period, especially over areas of economic and family life deemed "domestic." This dissertation examines periodicals, consumer research statistics, public opinion surveys, personal interviews, corporate archives, the archives of key women’s organizations, and government officials’ records to identify the role that women and household economies played in Brazilian developmentalism between 1945 and 1975. Its principal argument is that business and political elites attempted to define gender roles for adult urban women as housewives and mothers, linking their management of the household to familial well-being and national modernization. In turn, Brazilian women deployed these idealized roles in public to advance their own economic interests, especially in the management of household finances and consumption, as well as to expand legal rights for married women, and increase women’s participation in the workforce. As the market for women's labor expanded with continued industrialization, these efforts defined a more active role for women in the economy and in debates about the trajectory of national development policies.Item Seeds of Contestation: Genetically Modified Crops and the Politics of Agricultural Modernization in Ghana(2015) Ignatova, Jacqueline Alyce; Haufler, Virginia; Government and Politics; Digital Repository at the University of Maryland; University of Maryland (College Park, Md.)What actors, expertise, and models of development are advanced by the ‘new Green Revolution in Africa’? This dissertation addresses this question through a blend of discourse analysis and ethnographic fieldwork during a period of agricultural transition in Northern Ghana. What struggles over authority, knowledge, identity, and property define this contemporary political economy of agricultural modernization in Ghana? I argue that legal, techno-scientific expertise and agribusiness work together to advance a model of agricultural development based on new forms of capital, governance structures, and technology. This model of agricultural development is mobilized and legitimated through discourses of emergency, salvation, entrepreneurship, and humanitarianism. In this new Green Revolution in Africa, regions like Northern Ghana are seen by development planners as ‘backwards,’ with growing ‘yield gaps’ that undermine food security. What is needed, from this perspective, is capital investment, entrepreneurship, and access to yield-enhancing technologies, such as ‘pro-poor biotechnology.’ Deficiency frames, the combined use of hype and science, and donations become critical mechanisms to facilitate—or resist—the entry of contested agricultural technologies and models of agricultural development. At the center of these discursive strategies is the figure of the farmer, who is seen as an agent and object of salvation by proponents and opponents alike. I complement discourse analysis with ethnography to show that these grand plans to transform farming from a way of life to a business are constantly challenged by the existing complexity of Africans’ multiple, coexisting roles, risk reduction practices, and notions of entrepreneurship.Item Verb Learning Under Guidance(2015) He, Xiaoxue Angela; Lidz, Jeffrey; Linguistics; Digital Repository at the University of Maryland; University of Maryland (College Park, Md.)Any kind of uninstructed learning, faced by the challenge that any finite experience is consistent with infinitely many hypotheses, must proceed under guidance. This dissertation investigates guided vocabulary acquisition with a focus on verb learning. In particular, it examines some proposed early expectations that the young language learner may hold as guidance in learning novel verbs, and investigates the nature of these expectations from different angles. Four lines of studies are reported, each discussing a different question. Study 1 focuses on the expectation that the grammatical category verb picks out the conceptual category event - the verb-event bias, and examines the early developmental trajectory of this bias, which may shed light on its origin: whether it is specified within UG or generalized inductively from input. Study 2 further asks how specific/general the learner's initial expectations about verb meanings are, and thus what is the expected degree of extendibility of verb meanings. Study 3 investigates the proposed expectation that the number of event participants aligns with the number of syntactic arguments - the participant-argument-match (PAM) bias, and questions the utility of this bias in face of potential mismatch cases; in particular, some plausible 3-participant events are naturally described by 2-argument sentences. Study 4 looks at the proposed expectation that objects name patients (ONP) and asks a question about its exact nature in face of cross-linguistic variation - whether objects are expected to name patients of the clause's event, or to name patients of the verb's event, and whether it varies cross-linguistically. Together, this dissertation provides new evidence that the language learner acquires verb meanings under guidance, asks new questions about the natures of some verb-learning guides, and highlights several issues the current acquisition theory needs to address.Item Participatory Budgeting in the Dominican Republic: Implications for Agency, Democracy and Development(2014) Vasquez Duran, Marie Claire; Graham, Carol; Crocker, David A; Public Policy; Digital Repository at the University of Maryland; University of Maryland (College Park, Md.)This study examines participatory budgeting (PB) as an important kind of citizen participation in the Dominican Republic (DR) and the implications of this recent practice for agency, democracy, and development. PB is a process that intends to drive change with specific outcomes: through deliberative decision-making, ordinary citizens select well-being- and agency-enhancing projects that ideally lead to more local and authentic development. Together with the attainment of these tangible outcomes, valuable subjective states may also come about: people feel more in charge of their own lives, community groups become more collaborative and cooperative, and more and better democracy is fostered. Taking a step forward from previous studies that only focus on PB from an urban planning or public finance perspective, the overall objective of this study is to provide a deeper understanding and assessment of how PB works in the localities under analysis, its association with different measures of agency, the characteristics that drive its success or failure, and its general impact on the lives of individuals and communities. Drawing on normative and policy-based literatures and specifically following an agency-oriented capability approach, this study uses a mixed-methods approach to analyze interview, survey, and direct observations of PB public assemblies, and archival data with respect to the 2013 budget cycle in four DR municipalities. A regression analysis finds that participation in and awareness of PB are both significantly correlated with individuals reporting higher levels of individual and collective agency when compared to non-participants and unaware individuals. These measures of agency are contextualized to the municipal budget-planning cycle. A process tracing analysis concludes that PB is likely, under certain conditions, to increase democratic participation and deliberation. However, due to certain democratic deficits, PB in two DR municipalities does not always increase agency, group cooperative functioning, and good development. Thus, PB must be analyzed on a case-by-case basis because differences in the characteristics of each PB assembly may lead to different outcomes. It is finally argued that rather than condemning democracy because of the failures of the current PB system, we should advance PB's democracy further by improving it in various ways.