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 The Riverfront Wedge: Industrial Land Use on the Anacostia waterfront(2023) ALAJATI, FADI; Noonan, Peter; Architecture; Digital Repository at the University of Maryland; University of Maryland (College Park, Md.)The riverfront wedge (RFW) neighborhood struggles to remake itself because its identity is locked between its old production, distribution, and repair (PDR) zones and real-estate developers' expectations. RFW is isolated by freeways on two sides and the Anacostia River on the third. Therefore, the study will reimagine RFW by capitalizing on its unique location and proximity to the water, turning the PDR zoning infrastructure from a liability into an asset, and turning the vacant, disconnected property into a thriving neighborhood with connections to the 11th Street Bridge to the east and Capitol Hill to the north. The property's inaccessibility prevents it from being redeveloped like Navy Yard. Challenges addressed in this thesis:• Waterfront access • Affordable housing • Economic development for social justice, climate change and uplifting the community by providing an industrial institution where people can work, live, and gather in the same placeItem THE ROLE OF NEUROGENIN2 AND NEUROD1, AND THEIR DOWNSTREAM TARGETS, IN TRIGEMINAL GANGLION DEVELOPMENT(2022) Bina, Parinaz; Taneyhill, Lisa A; Animal Sciences; Digital Repository at the University of Maryland; University of Maryland (College Park, Md.)The trigeminal ganglion contains the cell bodies of sensory neurons comprising cranial nerve V and functions to relay information related to pain, touch, and temperature from the face and head to the central nervous system. Like other cranial ganglia, the trigeminal ganglion is composed of neuronal derivatives of two critical embryonic cell types, neural crest cells and placode cells. Neurogenesis within the cranial ganglia is promoted by Neurogenin2, which is expressed in trigeminal placode cells and their neuronal derivatives, and transcriptionally activates neuronal differentiation genes like Neuronal Differentiation 1 (or NeuroD1). Other targets downstream of Neurogenin2 and NeuroD1 include Drebrin1 and Stathmin2, cell polarity and cytoskeletal regulators that mediate changes in neuron cell shape during neurogenesis. Little is known, however, about the role of Neurogenin2, NeuroD1, and their downstream signaling pathways during trigeminal gangliogenesis in the chick embryo. By depleting Neurogenin2 and NeuroD1 from chick trigeminal placode cells with morpholino antisense oligonucleotides, we examined how these proteins influence chick trigeminal ganglion development. Additionally, we identified the expression of Drebrin1 and Stathmin2 in trigeminal ganglion neurons. Taken together, our results highlight, for the first time, functional roles for Neurogenin2 and NeuroD1 during chick trigeminal gangliogenesis. These studies will not only improve our understanding of the molecular mechanisms underlying trigeminal ganglion development, but may also provide insight into human and animal diseases of the peripheral nervous system.Item Assessing the Impact of Typical Variations in Stressful Life Events on Hippocampal Development in Childhood(2021) Botdorf, Morgan; Riggins, Tracy; Psychology; Digital Repository at the University of Maryland; University of Maryland (College Park, Md.)The negative impact of extreme stress on early brain development is well-documented. An emerging body of work suggests that less extreme and more typical variations in stressful experiences (e.g., parental divorce, changing schools) may also exert an impact on the brain, especially in early childhood; however, more systematic research is needed. Across, three studies, this dissertation addressed this gap by exploring effects of typical variations in stressful life events on development of the hippocampus, a brain region highly susceptible to stress. Study 1a assessed the impact of stressful life events on the development of hippocampal subfield volumes (i.e., CA1, CA2-4/dentate gyrus (DG), subiculum) in an accelerated longitudinal sample of 102 4- or 6-year-old children who were each followed for 3 years. Analyses revealed that experiencing more stressful life events was related to smaller CA1 and CA2-4/DG volumes in the 6- (but not 4-) year-old cohort. Study 1b used the same sample described in Study 1a to investigate the impact of stressful life events on functional connectivity between the hippocampus and stress-related cortical regions. Analyses revealed a significant association in the 4- (but not 6-) year-old cohort, such that experiencing more stressful life events was related to greater connectivity between the hippocampus and the insula, a region important for emotional processing. Study 2 assessed moderating effects of sex and socioeconomic status (SES) on the association between stressful events and hippocampal subfield volumes using a large (n = 4,348), diverse subsample of 9-10-year-old adolescents from the Adolescent Brain and Cognitive Development Study. Analyses revealed that stressful life events were related to smaller subiculum volumes, but these associations did not vary by sex or SES. Overall, these findings provide evidence of the impact of typical variations in stressful life events on both hippocampal structure and functional connectivity. Findings also highlight the complexity of stress effects on the brain as these experiences may impact the hippocampus in an age-dependent manner. These results advance our current understanding of how stress influences hippocampal development and pave the way for studies to assess the implications of findings both for cognitive processes and the development of stress-related disorders.Item Development of the translaminar circuits in the mouse cortex(2020) Deng, Rongkang; Kanold, Patrick O; Biology; Digital Repository at the University of Maryland; University of Maryland (College Park, Md.)The elaborated connections among cortical neurons form the cortical circuits, which are essential mechanisms underlying various cortical functions such as sensory perception, motor control, and other cognitive functions. The cortical circuits are composed of excitatory neurons and GABAergic interneurons. Excitatory neurons send excitatory connections to cortical neurons, while inhibitory neurons send inhibitory connections. Building the neural circuits is no easy task involving complex genetic programs and the influence of the environment through sensation. Malformation of the cortical circuits during development is implicated in causing neurological disorders, but our knowledge about the developmental process is scarce. The work in this dissertation uses in vitro electrophysiology in brain slices from transgenic mice to investigate how the excitatory connections onto GABAergic interneurons in the primary auditory cortex develop during the first two postnatal weeks. Furthermore, this dissertation explores the mechanisms that could regulate the early development of the cortical circuits by testing the requirement of sensory epithelium and N-methyl-D-aspartate receptors (NMDARs) in the early postnatal development of the neural circuits in the primary sensory cortex and temporal association cortex (TeA), respectively. Results from these studies fill crucial gaps in our understanding of how GABAergic interneurons are integrated into the cortical circuits and highlight the importance of sensory epithelium in the normal development of excitatory connections onto cortical GABAergic interneurons. My results also showed impaired development of GABAergic connections onto excitatory neurons lacking functional NMDARs in the TeA, suggesting an essential role of NMDARs for the early development of inhibitory circuits in the cortex.Item How Grammars Grow: Argument Structure and the Acquisition of Non-Basic Syntax(2019) Perkins, Laurel; Lidz, Jeffrey; Linguistics; Digital Repository at the University of Maryland; University of Maryland (College Park, Md.)This dissertation examines the acquisition of argument structure as a window into the role of development in grammar learning. The way that children represent the data for language acquisition depends on the grammatical knowledge they have at any given point in development. Children use their immature grammatical knowledge, together with other non-linguistic conceptual, pragmatic, and cognitive abilities, to parse and interpret their input. But until children have fully acquired the target grammar, these input representations will be incomplete and potentially inaccurate. Our learning theory must take into account how learning can operate over input representations that change over the course of development. What allows learners to acquire new knowledge from partial and noisy representations of their data, one step at a time, and still converge on the right grammar? The case study in this dissertation points towards one way to characterize the role of development in grammar acquisition by probing more deeply into the resources that learners bring to their learning task. I consider two types of resources. The first is representational: learners need resources for representing their input in useful ways, even early in development. In two behavioral studies, I ask what resources infants in their second year of life use to represent their input for argument structure acquisition. I show that English learners differentiate the grammatical and thematic relations of clause arguments, and that they recognize local argument relations before they recognize non-local predicate-argument dependencies. The second type of resource includes mechanisms for learning from input representations even when they are incomplete or inaccurate early in development. In two computational experiments, I investigate how learners could in principle use a combination of domain-specific linguistic knowledge and domain-general cognitive abilities in order to draw accurate inferences about verb argument structure from messy data, and to identify the forms that argument movement can take in their language. By investigating some of the earliest steps of syntax acquisition in infancy, this work aims to provide a fuller picture of what portion of the input is useful to an individual child at any single point in development, how the child perceives that portion of the input given her current grammatical knowledge, and what internal mechanisms enable the child to generalize beyond her input in inferring the grammar of her language. This work has implications not only for theories of language learning, but also for learning in general, by offering a new perspective on the use of data in the acquisition of knowledge.Item Development of the Episodic Memory Network in Early Childhood: Insights from Graph Theoretical Analysis(2019) Botdorf, Morgan Anna; Riggins, Tracy; Psychology; Digital Repository at the University of Maryland; University of Maryland (College Park, Md.)The hippocampal memory network has been identified in both children and adults and shown to be related to episodic memory ability. However, it remains unclear how its organization may differ across development, particularly during periods of large behavioral gains in memory ability. The goal of the present study was to utilize graph theoretical analysis to investigate the integration of the hippocampus within the memory network and segregation from other networks (i.e., fronto-parietal and cingulo-opercular attention networks) in the brain. Results indicated that with age, there was a general increase in connections between the hippocampus and both regions within the memory network and regions in other networks in the brain. These differences may contribute to improvements in memory typically observed in early childhood. Future analyses will examine relations with memory behavior and probe whether segregation is observed using other metrics, a sample of adult data, or other networks (e.g., sensorimotor).Item Development and the Early Animal Fossil Record: Evolution and Phylogenetic Applications(2016) Tweedt, Sarah Maureen; Delwiche, Charles F; Erwin, Douglas H; Cell Biology & Molecular Genetics; Digital Repository at the University of Maryland; University of Maryland (College Park, Md.)Although evolutionary developmental biology and paleontology are linked by the study of morphology, the application of development to paleontological questions has only recently become more prominent. The growth of a robust developmental genetic framework for studying the origin and evolution of morphological features, however, holds great promise for understanding ancient animal life. As paleontology provides the historical record as well as the temporal and environmental context of past morphological evolution, uniting knowledge of developmental genetic systems with this historical record will form a key synthetic approach to understanding the early evolution of developmental processes. Ultimately unraveling the sequence of ancient animal developmental evolution will require combining analysis of comparative developmental data, critical assessment of fossil morphology within a developmental framework, and the targeted exploration of specific geologic periods to fill in the missing record of key times in animal developmental evolution. This study addresses each of these three approaches. First, I provide a new compilation and evaluation of recent comparative and experimental developmental biology data to review the nature of developmental ‘toolkits’ at the origin of the most basal animal clades. I reconstruct early animal developmental capacities and integrate these data within a temporal framework to better understand the context of earliest animal development. Second, I assess longstanding evolutionary hypotheses about the origin of the panarthropod clade and the phylogenetic position of Cambrian ‘lobopod’ fossils by examining signal present within current morphological datasets. I apply new methods to fossil panarthropod phylogeny estimation and suggest strategies for developmentally-informed phylogenetic coding of morphological data. Third, I present the discovery of the oldest spicule-bearing fossil sponges in the rock record, which co-occur in latest Ediacaran strata with classic enigmatic Ediacaran fauna. I provide a formal systematic description of fossil material from localities in both Nevada and southern Namibia. The combined approaches presented herein are a first step towards a deeper integration of developmental principles in the study and discovery of ancient animal life, and contribute to our understanding of the evolution of ancient animal developmental processes.Item The Influence of Orthographic Experiences on the Development of Functional Phonological Unit in Spoken Word Production(2015) Li, Chuchu; Wang, Min; Human Development; Digital Repository at the University of Maryland; University of Maryland (College Park, Md.)The current dissertation project examined the influence of orthographic experiences on the development of the functional phonological unit in spoken word production in native Mandarin-speaking children. Functional phonological unit refers to the first selectable phonological unit after lexical selection in the planning of spoken word production. Previous research has shown that the acquisition of orthographic knowledge restructures literate speakers’ phonological representation and in particular, the acquisition of alphabetic orthographic knowledge improves children’s phonological awareness at the phonemic level. However, few studies have investigated the influence of orthographic experiences on phonological retrieval and encoding in spoken word production. The goal of this dissertation is to fill this gap. Four experiments were carried out to conduct the investigation. Participants consisted of native Mandarin speakers from four age groups with different orthographic experiences, including 1) Grade 1 children, who were comparatively more exposed to alphabetic Pinyin and had very limited Chinese character knowledge, 2) Grade 2 and Grade 4 children, who had better character knowledge and more exposure to characters, and 3) adult readers, who had the highest level of character knowledge and the most exposure to characters. Experiment 1 investigated whether the onset served as the functional phonological unit in producing monosyllables; Experiment 2 investigated whether the role of the onset in phonological retrieval and encoding was sustained when producing disyllabic words; Experiment 3 examined the role of the syllable segment (i.e., a syllable whose tone is indeterminate or an atonal syllable) in producing disyllabic words; Experiment 4 examined the role of the tonal syllable (i.e., tonal information is also included) in producing disyllabic words. Results showed that only Grade 1 children selected the onset as the functional phonological unit regardless of the word length during spoken word production and that additionally, they might process the rime segment and tone as a cohesive unit. By contrast, Grade 4 children and adults selected the syllable segment as the functional phonological unit. Grade 2 children were in their transitional stage of development, and they selected tonal syllable as the functional phonological unit. The different orthographic experiences of the four groups might contribute to the above differences. The current dissertation has important theoretical and pedagogical implications. The aforementioned findings help us better understand the mechanism of phonological processing, and as a result, may help educators develop more efficient pedagogical approaches to improve children’s phonological processing ability.Item AN EXPLORATION OF SOCIAL JUSTICE COMMITMENT: A GROUNDED THEORY INVESTIGATION OF STUDENT AFFAIRS PROFESSIONALS(2015) Pepin, Sean C; Drezner, Noah D; Counseling and Personnel Services; Digital Repository at the University of Maryland; University of Maryland (College Park, Md.)As part of the project to create a more democratic society, social justice work is a critical component, especially within higher education. Social justice work comes with a wide array of deeply challenging issues and obstacles to remaining engaged. The purpose of this study was to expose those challenges and understand how individuals traversed those challenges. By looking at what the challenges were and how individuals navigated them, this study also dove into the personal reasons why social justice work can be incredibly challenging. Through this grounded theory investigation, a model for social justice commitment emerged, which illustrates the iterative nature of social justice commitment. The result is that one’s commitment is a cycle of growth, beginning with one’s internal and external engagement. As individuals engage in social justice work, nine distinct challenges emerged from the data. These challenges interrupt a person’s engagement, and can either be resolved through the use of three identified motivating forces or can cause a person to retreat to a time of pause. Finally, one of the unique findings within this study was the relationship commitment has with the concept of hope. As challenges increase, individuals have a decreased sense of hope. Hope is a fundamental component of long-term engagement, and individuals appeared to move to towards the edge of hope throughout their long-term engagement; however, they did not appear to ever fully leave hope or commitment behind. Finally, this research moved from the discovery of a social justice commitment model towards the practical implications for such a model. By weaving the identified challenges and the emergent commitment model together, applications were created for individuals, institutions, and future research. The resulting implications focused primarily on critical self-reflection for individuals, an increase in robust content and reflection for institutions, and a new direction for social justice research to explore the affective domain of development.Item Childhood Events and Long-Term Consequences(2015) Palloni, Giordano; Galiani, Sebastian; Economics; Digital Repository at the University of Maryland; University of Maryland (College Park, Md.)Health and experiences in early childhood are strongly associated with adult outcomes. In this dissertation, I explore the association in detail with a focus on identifying the causal mechanisms that generate variation in early health and uncovering the parental behaviors that determine whether early health and living conditions evolve into long-term deficits or advantages. In chapter 1, I explore whether pre-conception maternal desire for children of a particular sex has implications for the health of children in Indonesia. I show that a simple fertility stopping model predicts that when a child is born of the mother’s preferred sex, they will receive more resources, and I test this prediction empirically using a longitudinal data set. I find that children born of the mother’s preferred sex are heavier, have a higher body mass index, and experience fewer illnesses. I provide evidence that reductions in subsequent fertility are the primary mechanism for these effects. The existing research measuring the long-term implications of early childhood conditions frequently fails to identify the mechanisms through which early deficits become life-long disadvantages. In chapter 2, I examine one instance where deficits may matter for long-term well-being. Using data from Indonesia, I find that when third trimester rainfall is fifty percent higher than expected, birth weight and relative size are approximately .23 standard deviations higher. Despite this early advantage, I find no persistent positive impact fifteen years later. However, parental investment appears to be negatively influenced by in utero exposure to rainfall, suggesting that parents compensate for early health conditions. To date, research on the long-term effects of childhood participation in subsidized housing has been limited by the lack of suitable identification strategies and appropriate data. In chapter 3, I, along with my co-authors, create a new, national-level longitudinal data set on housing assistance and labor market earnings to explore how children’s housing affects their later employment and earnings. We find that while naïve estimates suggest there are substantial negative consequences to childhood participation in subsidized housing, household fixed-effects specifications attenuate these negative relationships for some demographic groups and uncover positive and significant effects for others.