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
More information is available at Theses and Dissertations at University of Maryland Libraries.
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Item INTEGRATED PROCESS MODELING AND EXPERIMENTAL ANALYSIS FOR OPTIMIZING CONTINUOUS MANUFACTURE OF DRUG SUBSTANCE CARBAMAZEPINE(2024) Kraus, Harrison; Choi, Kyu Yong; Chemical Engineering; Digital Repository at the University of Maryland; University of Maryland (College Park, Md.)This dissertation presents a comprehensive study on the continuous manufacture (CM) of the drug substance (DS) carbamazepine (CBZ), a widely used anti-epileptic medication, aimed at enhancing process efficiency and product quality. The research progresses through a series of investigations, beginning with the development of kinetic models for CBZ synthesis from iminostilbene via two different synthetic routes using urea and potassium cyanate across various reactor setups, including batch and continuous flow systems. Discrepancies between batch and continuous models, particularly in yield prediction and impurity formation, are thoroughly examined and addressed through adjustments in reactant addition methods and system designs. This demonstrates the value of mechanistic modeling, a tool that has been undervalued in recent research particularly for its ability to compare between batch and continuous systems. Subsequently, the research delves into the crystallization processes, employing a population balance model (PBM) to study CBZ polymorph form III crystal formation, highlighting the influence of seed crystal size distribution on product crystal quality. It also provides novel strategies for modeling the evolution of crystal size distribution (CSD) due to nucleation and growth and evaluates the robustness of these strategies as seed CSD varies. Lastly, the scope is expanded to a holistic view of the integrated synthesis and crystallization process presenting one of the first studies of a complete DS CM system and emphasizing the development of a robust Quality-by-Control (QbC) framework. This includes the implementation of in-line Raman spectroscopy for real-time concentration monitoring, an active feedback level control system, dynamic modeling of impurity partitioning for enhancing disturbance mitigation across the CM process, and a retrograde design strategy that optimizes the upstream synthesis based on downstream purification capabilities/limitations. Through all these contributions, the dissertation aims to advance the modernization of continuous manufacturing practices in the pharmaceutical industry and promotes a shift towards more adaptive and controlled production environments.Item Connecting the Dots Across the Care Continuum: Addressing Behavioral Health in ACO Networks(2019) Anderson, Andrew; Franzini, Luisa; Health Services Administration; Digital Repository at the University of Maryland; University of Maryland (College Park, Md.)Accountable Care Organizations (ACOs) represent a shift from traditional fee-for-service payment systems that reward volume to payment models that reward providers for value (e.g. quality improvement and cost reduction). Hospitals that lead or participate in ACOs have the potential to work with other providers to bridge the gap between traditional medical and behavioral health services. The goal of this dissertation was to examine the structures, processes, and outcomes of care for hospitals that lead or participate in ACO networks. The overarching hypothesis was that ACO-affiliated hospitals provide better behavioral health care due to increased care coordination and increased connections to behavioral health providers. This dissertation had three aims: 1) compare the implementation of care coordination strategies between ACO affiliated hospitals and unaffiliated hospitals and examine whether the implementation of care coordination strategies varies by hospital payment model types; 2) compare the use of care coordination strategies between ACO-affiliated hospitals with and without in-network behavioral health providers; and 3) compare rates of follow-up after a hospitalization for mental illness between ACO-affiliated and unaffiliated hospitals. These aims build on each other to illustrate how hospitals that participate in ACOs are improving care coordination and the provision of behavioral health services. There were several meaningful findings. ACO-affiliated hospitals were more likely to use care coordination strategies compared to unaffiliated hospitals. Participation in global capitation and shared savings models was associated with greater use of care coordination strategies. Nearly two-thirds of ACO-affiliated hospitals did not have in-network behavioral health providers. ACO-affiliated hospitals had a significantly higher average unadjusted rates of follow-up after a hospitalization for mental illness at 7 days and 30 days post-discharge compared to unaffiliated hospitals. Hospitals are important components of the care continuum and will play a critical role in improving outcomes for patients with behavioral health conditions. Policy makers should include behavioral health related performance measures tied to performance-based payment arrangements in ACO programs. ACOs can be used as way to bridge behavioral, clinical, and social services to address the unique needs of individuals with behavioral health conditions.Item Quality-Aware Data Source Management(2015) Rekatsinas, Theodoros; Deshpande, Amol; Getoor, Lise; Computer Science; Digital Repository at the University of Maryland; University of Maryland (College Park, Md.)Data is becoming a commodity of tremendous value in many domains. The ease of collecting and publishing data has led to an upsurge in the number of available data sources --- sources that are highly heterogeneous in the domains they cover, the quality of data they provide, and the fees they charge for accessing their data. However, most existing data integration approaches, for combining information from a collection of sources, focus on facilitating integration itself but are agnostic to the actual utility or the quality of the integration result. These approaches do not optimize for the trade-off between the utility and the cost of integration to determine which sources are worth integrating. In this dissertation, I introduce a framework for quality-aware data source management. I define a collection of formal quality metrics for different types of data sources, including sources that provide both structured and unstructured data. I develop techniques to efficiently detect the content focus of a large number of diverse sources, to reason about their content changes over time and to formally compute the utility obtained when integrating subsets of them. I also design efficient algorithms with constant factor approximation guarantees for finding a set of sources that maximizes the utility of the integration result given a cost budget. Finally, I develop a prototype quality-aware data source management system and demonstrate the effectiveness of the developed techniques on real-world applications.Item LITERACY AND EDUCATIONAL QUALITY IMPROVEMENT IN ETHIOPIA: A MIXED METHODS STUDY(2012) McCormac, Meredith; Lin, Jing; Education Policy, and Leadership; Digital Repository at the University of Maryland; University of Maryland (College Park, Md.)This study examines the development of early grade reading skills as a means for quality improvement in global education. Specifically, this study explores the contextual factors that affect the achievement of early reading skills in Ethiopia and investigates the relationship between literacy and educational quality. The sequential explanatory mixed-methods design is employed to answer four research questions: 1. According to the Ethiopia Early Grade Reading Assessment (EGRA) dataset in the Addis Ababa region, what contextual factors affect achievement in basic literacy skills and how are they related? 2. According to qualitative data, how do parents' and teachers' perspectives explain and substantiate the contextual factors identified in the EGRA dataset and do other factors emerge? 3. Given the answers to the first two research questions, what are the factors associated with achievement that are most favorable and most challenging for literacy development? 4. Given the answer to the third research question, how can interventions for literacy development be best implemented in relationship to overall educational quality improvement? The first, quantitative phase of this study shows that a vast majority of students do not perform at expected levels on the Ethiopia EGRA. The results from three multiple regression analysis models for oral reading fluency and reading comprehension outcomes suggest that both in-school and out-of-school variables have a significant influence on student achievement. The second, qualitative phase of this study reveals several important findings above and beyond those identified in Phase I. First, the findings from both Phase I and Phase II demonstrate the importance of out-of-school variables, but the importance of these to both teachers and parents was underestimated in Phase I. School directors, parents, and teachers highlight the home environment as the most important factor in student achievement. This study demonstrates the utility of a mixed-methods approach to investigate more holistically the practice of literacy in Ethiopia and its relationship to the pursuit of educational quality more broadly. This study also provides a responsive, critical, and theoretical grounding for understanding conflicting perspectives, policies, and approaches to improving the quality of education through literacy development.Item Product Differentiation in International Trade(2009) Gervais, Antoine; Limao, Nuno; Economics; Digital Repository at the University of Maryland; University of Maryland (College Park, Md.)This thesis is concerned with the role of product quality in explaining observed price and trade patterns. The first chapter introduces the topic, summarizes the main findings of the dissertation and contrasts them to other results in the literature. The second chapter develops a tractable general equilibrium model that includes quality differentiation among heterogeneous firms. The theory explicitly demonstrates how heterogeneity in a single exogenous parameter, productivity, can produce dispersion in product quality and price. The framework predicts that relatively productive firms will choose to produce high quality varieties. This finding accords well with the observation that the unit value of exported varieties increases with exporter's income, capital- and skill- abundance. The model is used to analyze how international trade policy and quality differentiation interact to shape patterns of production and trade flows. In particular, the model predicts a positive relationship between product quality and export status at the firm level and that trade liberalization decreases the average quality of a country's exports. The third chapter evaluates the importance of vertical product differentiation in explaining price and export status patterns observed in microdata on U.S. manufacturing plants. The main difficulty in exploring the impact of vertical product differentiation is that product quality is not directly observable. The analysis tackles the problem from two angles. First, the chapter develops a novel empirical strategy to obtain a proxy for quality, which is then used to evaluate important conditional correlations. The results show that both quality and productivity are important determinants of price and export status pattern. Second, the simulated method of moments is used to obtain structural estimates of the parameters of the model and to assess the importance of quality differentiation. The estimates suggest that quality differentiation plays an important role in explaining the variation in price, size and export status across U.S. manufacturing plants. The fourth chapter briefly concludes by summarizing the main findings and suggesting avenues for future research. Overall the analysis presented in this dissertation implies that vertical product differentiation, or quality, plays an important role in explaining dispersion in producer output price and export status.Item The Relations Among Childcare Provider Education, Neighborhood Poverty, and the Quality of Childcare Classrooms(2008-08-03) D'Amour, Allison Catherine; Jones Harden, Brenda; Human Development; Digital Repository at the University of Maryland; University of Maryland (College Park, Md.)The current study examined contextual influences on the quality of the childcare classroom. Previous research has examined how direct influences, such as childcare provider education, impact childcare quality, but to date, no research has examined how these direct influences interact with distal features, such as neighborhood poverty. Given the large number of children enrolled in childcare and the evidence that high quality childcare benefits children, it is important to identify what contributes to classroom quality. Using hierarchical linear modeling, this study examined (1) if childcare quality varies across neighborhoods, (2) if childcare provider education and (3) neighborhood poverty individually impact classroom quality, and (4) if the impact of childcare provider education on classroom quality varies as a function of the neighborhood. Data collected from the United Way of Southeastern Pennsylvania's Early to Learn project was used in combination with poverty data derived from the 2000 U.S. Census. Results of the present study were that childcare quality did vary across neighborhoods, but that childcare provider education had no direct impact on classroom quality. However, neighborhood poverty was positively associated with classroom quality. Additionally, there was no differential impact of childcare provider education on quality in the context of the neighborhood. Although these findings may seem to suggest that childcare provider education does not matter, further analyses reveal that higher education was positively related to structural features of the classroom, such as group size and staff: child ratios. Additionally, providers with Associate's degrees and Child Development Associates had the highest quality classrooms, higher than those with a Bachelor's degree and with High School education. More research is needed to fully understand the impact of the childcare provider in the classroom. The findings that classrooms in higher poverty had higher quality classrooms, in addition to the lack of findings regarding childcare provider education, have major implications for future research and policies aimed at improving childcare quality.