UMD Theses and Dissertations
Permanent URI for this collection
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.
More information is available at Theses and Dissertations at University of Maryland Libraries.
Browse
Recent Submissions
Item CHARACTERISTICS AND HEALTH INSURANCE COVERAGE AMONG ADOPTED CHILDREN IN THE UNITED STATES(2024) Fleishman, Jamie Lin; Yue, Dahai; Health Services Administration; Digital Repository at the University of Maryland; University of Maryland (College Park, Md.)The practice of adopting a child is a common occurrence within the United States. Research on adoption, birth parents, and adoptive parents has traditionally focused on psychology and social work outcomes. This master’s thesis shifts the focus of adoption outcomes to a public health perspective, examining the demographics, socioeconomic conditions, and health insurance rates of domestic and international adoptees. To help determine the rates of any health insurance, public health insurance, and private health insurance, this thesis examined American Community Survey 2022 5-year data, a nationally representative study of adoptees and their counterparts—non-adoptees who are biologically related to their parents or head of household. It was determined that domestic adoptees and non-adoptees had similar demographic and socioeconomic statuses whereas international adoptees were predominantly non-Hispanic Asians, females, and have wealthier and White heads of households. After controlling for demographic and socioeconomic variables, it was discovered that international adoptees have higher uninsured rates compared to non-adoptees and domestic adoptees, which could be attributed to geographic differences in health insurance coverage. Further research is needed to examine health insurance coverage rates in the United States for adoptees.Item Second Wave Mechanics(2024) Fabbri, Anthony; Herrmann, Jeffrey W; Mechanical Engineering; Digital Repository at the University of Maryland; University of Maryland (College Park, Md.)The COVID-19 pandemic experienced very well-documented "waves" of the virus's progression, which can be analyzed to predict future wave behavior. This thesis describes a data analysis algorithm for analyzing pandemic behavior and other, similar problems. This involves splitting the linear and sinusoidal elements of a pandemic in order to predict the behavior of future "waves" of infection from previous "waves" of infection, creating a very long-term prediction of a pandemic. Common wave shape patterns can also be identified, to predict the pattern of mutations that have recently occurred, but have not become popularly known as yet, to predict the remaining future outcome of the wave. By only considering the patterns in the data that could possibly have acted in tandem to generate the observed results, many false patterns can be eliminated, and, therefore, hidden variables can be estimated to a very high degree of probability. Similar mathematical relationships can reveal hidden variables in other underlying differential equations.Item TRANSITIONING VISUALLY IMPAIRED USERS TO UTILIZE ACCESSIBILITY TECHNOLOGY(2024) Jo, Hyejin; Reitz, Galina; Library & Information Services; Digital Repository at the University of Maryland; University of Maryland (College Park, Md.)In a world increasingly driven by visual information, this research develops the Transition Experience Interface (TEI), dedicated to supporting individuals adapting to visual impairments with advanced accessibility technologies. TEI features a user-centric design with a mobile user interface that includes tutorials, updates on new features, a voice command guide, and a progress dashboard. These components aim to reduce dependency on visual cues, enhancing digital inclusivity and promoting independence by encouraging the use of built-in accessibility features on smartphones. TEI educates users on their devices’ capabilities and fosters habitual use of these features, preparing them to rely less on vision and more on voice commands and other settings. This proactive approach helps users operate their smartphones confidently and independently as their visual function changes, bridging the gap between traditional tools and user needs, and highlighting the potential of inclusive design.Item A Framework for Remaining Useful Life Prediction and Optimization for Complex Engineering Systems(2024) Weiner, Matthew Joesph; Azarm, Shapour; Groth, Katrina M; Reliability Engineering; Digital Repository at the University of Maryland; University of Maryland (College Park, Md.)Remaining useful life (RUL) prediction plays a crucial role in maintaining the operational efficiency, reliability, and performance of complex engineering systems. Recent efforts have primarily focused on individual components or subsystems, neglecting the intricate relationships between components and their impact on system-level RUL (SRUL). The existing gap in predictive methodologies has prompted the need for an integrated approach to address the complex nature of these systems, while optimizing the performance with respect to these predictive indicators. This thesis introduces a novel methodology for predicting and optimizing SRUL, and demonstrates how the predicted SRUL can be used to optimize system operation. The approach incorporates various types of data, including condition monitoring sensor data and component reliability data. The methodology leverages probabilistic deep learning (PDL) techniques to predict component RUL distributions based on sensor data and component reliability data when sensor data is not available. Furthermore, an equation node-based Bayesian network (BN) is employed to capture the complex causal relationships between components and predict the SRUL. Finally, the system operation is optimized using a multi-objective genetic algorithm (MOGA), where SRUL is treated as a constraint and also as an objective function, and the other objective relates to mission completion time. The validation process includes a thorough examination of the component-level methodology using the C-MAPSS data set. The practical application of the proposed methodology in this thesis is through a case study involving an unmanned surface vessel (USV), which incorporates all aspects of the methodology, including system-level validation through qualitative metrics. Evaluation metrics are employed to quantify and qualify both component and system-level results, as well as the results from the optimizer, providing a comprehensive understanding of the proposed approach’s performance. There are several main contributions of this thesis. These include a new deep learning structure for component-level PHM, one that utilizes a hybrid-loss function for a multi-layer long short-term memory (LSTM) regression model to predict RUL with a given confidence interval while also considering the complex interactions among components. Another contribution is the development of a new framework for computing SRUL from these predicted component RULs, in which a Bayesian network is used to perform logic operations and determine the SRUL. These contributions advance the field of PHM, but also provide a practical application in engineering. The ability to accurately predict and manage the RUL of components within a system has profound implications for maintenance scheduling, cost reduction, and overall system reliability. The integration of the proposed method with an optimization algorithm closes the loop, offering a comprehensive solution for offline planning and SRUL prediction and optimization. The results of this research can be used to enhance the efficiency and reliability of engineering systems, leading to more informed decision-making.Item TEACHER PRACTICES AROUND REPERTOIRE LEARNING AND SELECTION IN THE ELEMENTARY GENERAL MUSIC CLASSROOM(2024) Nixon, Elizabeth Rivera; Elpus, Kenneth; Music; Digital Repository at the University of Maryland; University of Maryland (College Park, Md.)In music education, it is sometimes said that “the repertoire is the curriculum.” This research seeks to study the ways that elementary general music teachers select repertoire for use in their classrooms, and how the repertoire that they choose in turn influences what students are taught. By interviewing four elementary general music teachers about their practices around repertoire selection, with a focus on one specific lesson, I attempted in this research to answer the following questions:What resources (textbooks, digital resources, etc.) do teachers report utilizing when seeking repertoire for use in their classrooms? When selecting repertoire for their classrooms, what musical and extra-musical factors do elementary general music teachers consider? How do teachers describe the influence of repertoire selection on the concepts taught in elementary general music classrooms? After conducting these interviews and analyzing the data collected, I have determined that the teachers in this study report drawing repertoire from a variety of different resources, including digital resources, print books, and their colleagues. From these resources, they select repertoire based on a variety of overlapping selection criteria, including content-based, aesthetic, functional, and repertoire that provides opportunities for learning about different cultures. The repertoire selected has impacts on the remainder of the lesson, whether through pedagogical or structural impacts. Finally, this paper discusses the impacts of teacher pedagogical approaches on repertoire selection, and the ways in which repertoire is transmitted between colleagues within the world of elementary general music education.Item THE EMBODIED EMOTIONAL EXPERIENCES OF BLACK MEN PARTICIPATING IN A HOSPITAL-BASED VIOLENCE INTERVENTION PROGRAM(2024) Wical, William Grant; Richardson, Joseph; Anthropology; Digital Repository at the University of Maryland; University of Maryland (College Park, Md.)Gun violence is a public health and racial justice issue which requires significant societal change to effectively decrease its impact on the lives of Black men and their communities. While hospital-based violence intervention programs have been identified as a promising mode of prevention, they have largely overlooked the ways Black men who survive gunshot wounds feel, determine what constitutes effective violence prevention, and subjectively experience trauma. This dissertation explores how those who received psychosocial support from an intervention program interpret their emotional experiences related to trauma, healing, and loss to make claims about society, themselves, and justice. Their affective experiences contrast significantly with dominant discourses of violence, race, and emotionality. Attention to these emotional experiences can provide a foundation for a fundamentally different ethics of caring. This redefinition of what it means to provide care challenges the current usage of trauma as the primary analytic to evaluate Black men’s experiences related to violence and underscores the need to shift prevention efforts away from individualistic models toward those geared at creating structural change.Item Literacy Based Behavioral Interventions for Autistic and Neurotypical Children(2024) Pepkin Dataram, Sara Anne; Kang, Veronica; Special Education; Digital Repository at the University of Maryland; University of Maryland (College Park, Md.)The neurodiversity model of disability is a relatively new approach to teaching and working with autistic individuals. As a result, many interventions align with earlier models of disability, such as the medical and social models, and aim to assimilate autistic individuals among their neurotypical peers rather than celebrate their differences as one of life’s natural diversities. This study investigates how educators can create Literacy Based Behavioral Interventions (LBBIs) that align with the neurodiversity paradigm and foster equitable friendships between autistic and neurotypical children. I conducted focus groups with 34 autistic middle school and high school students and eight educators to determine how to feasibly meet autistic students’ social needs. Themes found across these focus groups included autism education for teachers and neurotypical peers, barriers to communication, and the impact of social stigma against autistic individuals. These findings indicate a need for LBBIs and overall classroom environments that amplify autistic perspectives and are not rooted in neurotypical standards.Item In Pursuit of a Nonpublic Special Education Placement(2024) Healy, Charlotte Eileen; Scribner, Campbell F; Education Policy, and Leadership; Digital Repository at the University of Maryland; University of Maryland (College Park, Md.)Although the Individuals with Disabilities Education Act (IDEA) intends parents to be equal members of the team that makes their child's Individual Education Plan (IEP), parents face barriers to participation, particularly exclusionary procedures, school structures, professional behaviors, and racial and cultural biases. Little wonder that some seek placements outside the public school system. However, IDEA also mandates that students receive services in the “least restrictive environment,” which means alongside peers without disabilities to the maximum extent appropriate. This dissertation is an exploratory, qualitative study of parents who pursue publicly funded special education placements in nonpublic institutions for students with autism spectrum disorders (ASD). This research documents parents’ reasons, perceptions, and experiences when seeking a nonpublic placement, as well as their strategies and challenges. The questions, and my interpretation of responses, are informed by Pierre Bourdieu’s (1985) socio-cultural capital theory, as well as Audrey A. Trainor’s (2010a, 2010b) descriptions of social and cultural capital use when advocating for children with disabilities. This study found parents of children with ASD sought nonpublic placement only when significant issues arose in their child’s public school, particularly around their child’s safety or lack of meaningful improvement, and only after their efforts to resolve these issues failed and their distrust of school and district personnel grew. No longer focused on coming to a consensus or compromise with their child’s IEP team, parents began an advocacy process that involved: a) consulting or retaining professional representation (attorneys, professional advocates, and/or educational consultants); b) building and presenting the argument that the school district was and could not providing a free and appropriate public education (FAPE); c) securing a placement in a nonpublic school.Item Examination of US Transportation Public-Private Partnership Experience: Performance and Market(2024) Zhang, Kunqi; Cui, Qingbin; Civil Engineering; Digital Repository at the University of Maryland; University of Maryland (College Park, Md.)Worldwide, public-private partnership (P3) project performance and benefits accrued to market participants are understudied. Focusing on the US, this dissertation examines the country’s transportation P3 experience through three empirical studies comparing P3 to design-bid-build (DBB), the traditional delivery method. Throughout, the Information Source for Major Projects database, built by a University of Maryland team in which the author led the data collection effort, served as the data source. In the first study, the researchers examined P3 cost and time performance using piecewise linear growth curve modeling, recognizing that past cross-sectional studies had produced mixed results. With 133 major transportation projects, the longitudinal analysis confirmed P3’s time performance advantage and efficiency diffusion effecting cost savings in DBB, where efficiency diffusion was a new term describing the spillover and internalization of technical and managerial innovations inducing an efficient outcome. The second study used social network analysis to investigate collaboration patterns among different types of players in the P3 market (i.e., public sponsors, special purpose vehicles, investors, lenders, advisors, contractors, and professional service firms). With 135 projects and 1009 organizations, data found that both P3 and DBB networks are small worlds. Exponential random graph modeling revealed that practicing in the DBB market helps firms participate in P3 projects and that large firms (vis-à-vis small/medium-sized firms) are not privileged. The third study, further exploring the P3 market, focused on the Disadvantaged Business Enterprise (DBE) program. Administered by the US Department of Transportation, the program promotes the participation of small, disadvantaged firms in federal-aid projects. Linear regressions on 134 contracts showed that P3 associates with higher DBE goals in terms of percentage of dollars to be awarded to DBEs, whereas the delivery method does not affect the actual attainment. Overall, the findings justify continued policy support towards P3 implementation.Item Essays on investor preferences and corporate strategies(2024) Nguyen, Huu Loc; Sampson, Rachelle; Business and Management: Logistics, Business & Public Policy; Digital Repository at the University of Maryland; University of Maryland (College Park, Md.)Time horizon, an investment’s expected payback period, is a consequential investor preference and a crucial determinant of corporate strategy as it can constrain firms’ investment options. However, a gap exists between research focusing on investor temporal preferences and on corporate intertemporal strategy. Therefore, my dissertation offers a multi-level analysis to examine the dynamic relationship between investor temporal preferences and firm strategy. In the first essay, I construct a real-options signaling game model in which time horizon serves as a key determinant of firm strategic responses to shifts in investor temporal preferences. I test my predictions using the emergence of low-carbon energy innovation in the U.S. Oil and Gas industry during 1980-2018. I find that firms adjust their strategies in response to changes in investor time horizons. When faced with a lengthened investor time horizon, firms are more inclined to prioritize long-term inventive innovation, whereas a shortened investor time horizon prompts a greater focus on short-term adoptive innovation. Furthermore, I find suggestive evidence that such commitments when firms align their strategies to investor temporal preferences enhance firms' innovation performance. The second essay extends my investigation in the first chapter to explore the impacts of the inherent information asymmetry between firms and investors on investor-induced firm strategies. I find that, in high information asymmetry contexts, firms overshoot their investor-induced responses to effectively signal their alignment to shifts in investor temporal preferences. In the third (co-authored) essay, we explore the interplay between investor temporal preferences and firm strategies via top management teams. We study how the career experience of top management influences firm strategies and investor temporal preferences. We construct a novel metric to capture, standardize, and compare executives’ career paths across different functional roles, firms, and industries. Our findings indicate that executives with heightened diversity of experience across various functional roles tend to support longer-term strategies, such as income smoothing over time, aligning with the interests of long-term investors. In contrast, executives with more transitions between firms and industries often exhibit more short-term actions, namely cuts in R&D investments, rendering their firms more appealing to short-term investors.Item DO INTERIOR PRIVATELY OWNED PUBLIC SPACES FOSTER URBAN PUBLIC LIFE? A COMPARATIVE STUDY OF FOUR NYC PUBLIC SPACE TYPOLOGIES(2024) Donahue, Alex; Simon, Madlen; Urban and Regional Planning and Design; Digital Repository at the University of Maryland; University of Maryland (College Park, Md.)This dissertation focuses on a specific kind of public space—privately owned and mandated for public use and enjoyment. In exchange, the property owner receives bonus floor area or waivers. The arrangement provides a unique dilemma: how can a space provide ideal benefits to the public while recognizing the individual rights associated with a privately owned space? The primary inquiry of this research is to compare Interior Privately Owned Public Spaces (IPOPS) with three other space typologies: Privately Owned, Restricted to Public Space (PORPS), Privately Owned, Publicly Available Space (POPAS), and Urban Street (URBS) to discover how successfully the physical characteristics of IPOPS foster urban public life, focusing on aspects of (a) sociability; (b) inclusion; (c) wayfinding; (d) ownership; (e) well-being; and (f) community. The six themes comprise the Hexa-model for assessing ideal space, a tool the researcher developed for this study. I use the following methods to understand better the connection between the built environment, human use, and interaction: (a) architectural analysis; (b) signage analysis; (c) behavioral observation; and (d) archival analysis. I focus on four case study sites within New York City, each including all four typologies: (a) along Maiden Lane from Water Street to South Street; (b) on East 42nd Street and Park Avenue; (c) around 3rd Avenue and East 49th Street; and (d) along 45th Street between 7th and 8th Avenues. The findings illustrate that while the IPOPS included free-of-charge access to secure, sheltered, and climate-controlled seating, tables, natural light, bathrooms, and plants, there was a relative lack of urban public life. The IPOPS demonstrated a lack of urban public life in limited occupancy and activity when compared to the other spatial typologies and a lack of public space legibility, a generic identity with little sense of place, impromptu closures, a fortress-like aesthetic, and rules that conscribe and exclude the types of uses that are allowed to occur within the space. This research illustrates that in the sample of spaces studied, and compared with other spatial typologies, IPOPS lacked several normative criteria outlined in the Hexa-model. As a consequence, the public is currently not receiving the full benefit of public space as outlined in the agreements made with the city of New York. I recommend that further study be conducted at a larger scale, covering more locations and at various times of day and year to confirm the present study’s findings and promote policy changes to improve the public nature of IPOPS.Item POLICY IMPACTS FOR DEVELOPMENT: EXAMPLES FROM A MARRIAGE LAW AND A LAND REFORM(2024) Chen, Ying; Battistin, Erich; Agricultural and Resource Economics; Digital Repository at the University of Maryland; University of Maryland (College Park, Md.)This abstract outlines the chapters that form my doctoral dissertation. The first two chapters analyze the impacts of the 1974 Age-of-Marriage law in Indonesia, which aimed to curb child marriage.In the first chapter, I study the effectiveness of age-of-marriage laws. I discuss how age-of-marriage restrictions delay marriages and also affect the marriage market equilibrium, including not only when people marry but also who they marry. I build a theoretical model and illustrate graphically what happens when a law abruptly shifts the supply of marriageable brides and grooms. My model predicts that the age-of-marriage laws are expected to postpone first marriages universally. However, the extent of their impact on the marriage market varies depending on the strength of age-related preferences. In cases where individuals strongly favor a specific age gap between spouses, no marriage market effects are anticipated. Conversely, under weaker age-related preferences, the law alters matching in the marriage market and can affect bride prices, age gaps, or marriage rates. I then test some of those predictions with regression discontinuity estimates using birth cohort as the running variable. Using a large nationally-representative dataset, I estimate impacts of the Indonesian Law on age of marriage and probability of underage marriage for both women and men. In addition, I examine marriage-market effects by estimating impacts on the age gap between spouses as well as spouse education. My estimations based on large survey datasets support the notion that the marriage law delayed marriages and prevented under-age marriages, and also altered matching patterns, at least in the short run. Because the estimation in an RD design is complicated by the misreporting of birth dates, I deploy a range of robustness checks to bolster my findings. Though some of the robustness checks raise important caveats, my overall findings still suggest the law effectively delays marriage and alters matching in the marriage market. The second chapter further explores the effects of delaying marriage on life outcomes. I continue to rely on Indonesia’s Age-of-Marriage law and the same nationally representative dataset. I leverage a fuzzy regression discontinuity design to explore whether the law further brought about other commonly expected desirable outcomes of delayed marriage, such as higher education attainment, employment participation, health, wealth, and more. My results show that the law had a strong impact on girls education. It led to significant increases in all completion rates for girls, from primary school to bachelor degrees. This is consistent with some existing studies finding that delayed marriage can prevent girls from dropping out of school. I do not find similar impacts for men, for whom the marriageable age is 19. My results further do not suggest strong impacts on employment, but I significant positive effects on access to banking and communications, as well as health insurance. Echoing results from Chapter 1, I find strong impacts on spouse outcomes, suggesting that women who delayed their wedding married more educated and more successful men. The third chapter examines the land rental market effects of increased tenure security in the context of China’s land titling reform. Between 2009 and 2018, the Chinese government introduced a nationwide reform to register land titles for rural individual households in over 600,000 villages. To estimate the causal effect of the land reform, I leverage differences across villages induced by a pilot project of the reform conducted between 2009 and 2013. Estimates suggest that registering land titles for individual households led to a substantial increase in their participation in farmland rental markets, and allowed a shift towards non-kin tenants with a higher willingness to pay.Item What's Playing? Immediacy, Authenticity, and Playfulness in the Work of Christophe Honoré, Ahmed Madani, and Faustine Noguès(2024) Muravchik, Madeline; Eades, Caroline; French Language and Literature; Digital Repository at the University of Maryland; University of Maryland (College Park, Md.)Christophe Honoré’s Le Ciel de Nantes (2021), Ahmed Madani’s Incandescences (2021), and Faustine Noguès’ Surprise parti (2019) represent a new wave of French playwrights who have rejected postmodern aesthetics and have intentionally returned to traditional classic French theater techniques - immediacy, authenticity, and playfulness - in order to create compelling theater for contemporary French audiences despite being confronted with the development of film and social media. These works rely specifically on the synchronous co-presence of performer and spectator. They create intimate portraits of different aspects of French life, drawing on material from both auto/biography and fiction. At their core, these elements are used to explore liveness, whether thematically by looking at an array of human connections (self to family, self to community, self to society), or artistically by exploring the nature of representation and play on stage.Item Perpetuating Disadvantage: An Investigation of Racial Bias Embedded in Criminal History Records(2024) Houlihan, Sean Patrick; Johnson, Brian D; Criminology and Criminal Justice; Digital Repository at the University of Maryland; University of Maryland (College Park, Md.)Criminal history records are an integral component of the criminal legal system. They are typically seen as unbiased measures of prior offending that inform assessments of an individual’s dangerousness and risk of reoffending. Criminal records are incorporated into the decision-making calculus of legal actors such as police, prosecutors, and judges. Moreover, they have significant influence in the development of legal policies across all sectors of the system. In consequence, individuals with criminal history records face significant disadvantages in the likelihood of contact with the legal system and subsequent criminal punishment. Scaling legal decision making and policy to an individual’s prior criminal history is largely implemented to focus resources on apprehending and punishing the most dangerous offenders. For this to be accomplished effectively, criminal history records are required to be unbiased representations of prior offending. However, the collective evidence of racial and ethnic inequality in the criminal legal system calls into question the neutrality of criminal history records. Rather than being unbiased, criminal history records may instead be a source of systemic racism, as these records are merely reflections of criminal legal outcomes often shown to be subject to racial and ethnic inequality.Utilizing a framework that outlines the pathways for decision making and policy structures to produce inequalities in legal outcomes, the current dissertation examines the extent to which criminal history records contain racial and ethnic bias. Theoretical predictions are tested using data from the National Longitudinal Survey of Youth 1997 (NLSY97). Specifically, NLSY97 data are used to test for racial and ethnic differences in outcomes related to criminal records, net of self-reported engagement in delinquency. The results provide mixed evidence of racial and ethnic disadvantage in outcomes related to arrest, conviction, and incarceration. Evidence of inequality in the outcomes of interest is more consistent across race than across ethnicity. Both racial and ethnic inequalities, when evidenced, were mediated by external factors. In particular, measures of individual risk factors and socioeconomic status strongly mediated the relationship between race, ethnicity, and legal outcomes. Despite nuances, findings from the current study largely support the theoretical supposition that criminal history records are not unbiased measures of prior offending but are instead imperfect proxies that are influenced by inequalities in the apprehension and punishment of individuals in the criminal legal system. Future research is needed to further explore the extent to which criminal records are embedded with bias and compound racial and ethnic inequality.Item TOWARDS AUTOMATION OF HEMORRHAGE DIAGNOSTICS AND THERAPEUTICS(2024) Chalumuri, Yekanth Ram; Hahn, Jin-Oh; Mechanical Engineering; Digital Repository at the University of Maryland; University of Maryland (College Park, Md.)The main aim of the thesis is to advance the technology in the development ofalgorithms and methodologies that will advance the care in hemorrhage diagnostics and therapeutics in low resource settings. The first objective of this thesis is to develop algorithms to primarily detect internal hemorrhage using non-invasive multi-modal physiological sensing. We developed a machine learning algorithm that can classify various types of hypovolemia and is shown to be performing superior to the algorithms developed primarily based on vital signs. To address the limitations in the data-driven approaches, we explored physics-based approaches to detect internal hemorrhage. In silico analysis showed that our physics-based algorithms can not only detect hemorrhage but also can detect hemorrhage even when hemorrhage is being compensated by fluid resuscitation. The second objective is to advance the regulatory aspects of physiological closed-loopcontrol systems in maintaining blood pressure at a desired value during hemorrhage and resuscitation. Physiological closed-loop control systems offer an exciting opportunity to treat hemorrhage in low resource settings but often face regulatory challenges due to safety concerns. A physics-based model with rigorous validation can improve regulatory aspects of such systems but current validation techniques are very naive. We developed a physics-based model that can predict hemodynamics during hemorrhage and resuscitation and validated these factors using a validation framework that uses sampled digital twins. Then we utilized the validated model to evaluate its efficacy in predicting the performance capability of the model and virtual patient generator in predicting the closed-loop controller metrics of unseen experimental data. To summarize, we tried to improve the hemorrhage care using novel algorithmdevelopment and in silico validation and evaluation of computation models that can be used to treat hemorrhage.Item HIGH PERFORMANCE NANOPHOTONIC CAVITIES AND INTERCONNECTS FOR OPTICAL PARAMETRIC OSCILLATORS AND QUANTUM EMITTERS(2024) Perez, Edgar; Srinivasan, Kartik; Hafezi, Mohammad; Physics; Digital Repository at the University of Maryland; University of Maryland (College Park, Md.)Integrated photonic devices like photonic crystals, microring resonators, and quantum emitters produce useful states of light, like solitons or single photons, through carefully engineered light-matter interactions. However, practical devices demand advanced integration techniques to meet the needs of cutting-edge technologies. High performance nanophotonic cavities and interconnects present opportunities to solve outstanding issues in the integration of nanophotonic devices. In this dissertation I develop three core tools required for the comprehensive integration of quantum emitters: wavelength-flexible excitation sources with sufficient pump power to drive down stream systems, photonic interconnects to spatially link the excitation sources to emitters, and cavities that can Purcell enhance quantum emitters without sacrificing other performance metrics. To create wavelength-flexible excitation sources, a high-performance χ(3)microring Optical Parametric Oscillator (OPO) is realized in silicon nitride. Microring OPOs are nonlinear frequency conversion devices that can extend the range of a high-quality on-chip (or off-chip) laser source to new wavelengths. However, parasitic effects normally limit the output power and conversion efficiency of χ(3)microring OPOs. This issue is resolved by using a microring geometry with strongly normal dispersion to suppress parasitic processes and multiple spatial mode families to satisfy the phase and frequency matching conditions. Our OPO achieves world-class performance with a conversion efficiency of up to 29% and an on-chip output power of over 18 mW. To create photonic interconnects, Direct Laser Writing (DLW) is used to fabricate 3-dimensional (3D) nanophotonic devices that can couple light into and out of photonic chips. In particular, polymer microlenses of 20 μm diameter are fabricated on the facet of photonic chips that increase the tolerance of the chips to misaligned input fibers by a factor of approximately 4. To do so, we develop the on-axis DLW method for photonic chips, which avoids the so-called "shadowing" effect and uses barcodes for automated alignment with machine vision. DLW is also used to fabricate Polymer Nanowires (PNWs) with diameters smaller than 1 μm that can directly couple photons from quantum emitters into Gaussian-like optical modes. Comparing the same quantum emitter system before and after the fabrication of a PNW, a (3 ± 0.7)× increase in the fiber-coupled collection efficiency is measured in the system with the PNW. To refine the design of quantum emitter cavities, a toy model is used to understand the underlying mechanisms that shape the emission profiles of Circular Bragg Gratings (CBGs). Insights from the toy model are used to guide the Bayesian optimization of high-performance CBG cavities suitable for coupling to single-mode fibers. I also demonstrate cavity designs with quality factors (Q) greater than 100000, which can be used in future experiments in cavity quantum electrodynamics or nonlinear optics. Finally, I show that these cavities can be optimized for extraction to a cladded PNW while producing a Purcell enhancement factor of 100 with efficient extraction into the fundamental PNW mode. The tools developed in this dissertation can be used to integrate individual quantum emitter systems or to build more complex systems, like quantum networks, that require the integration of multiple quantum emitters with multiple photonic devices.Item Race, Disadvantage, and the Probability of Arrest: A Multi-Level Study of Baltimore Neighborhoods (2016-2018)(2024) Placzkowski, Madisen; Velez, Maria; Criminology and Criminal Justice; Digital Repository at the University of Maryland; University of Maryland (College Park, Md.)This study examines the relationship among neighborhood racial composition, concentrated disadvantage, and the probability of an arrest following a Part 1 crime report. Racial threat theory predicts that as the proportion of Black residents increases over time (dynamic proxy for racial threat), the use of formal social control will increase, while the benign neglect hypothesis predicts that formal social control will diminish in areas with relatively higher proportions of Black residents (static proxy for racial threat). I test racial threat theory and the benign neglect hypothesis for both citizen-initiated and officer-initiated Part 1 crime reports, using Baltimore Police Department crime reports and arrest data, as well as block group characteristics from the 2011-2015 American Community Survey. Through multi-level modeling and including both static and dynamic measures of racial threat, I find that proportion Black is negatively associated with the probability of arrest; concentrated disadvantage has no effect. This finding supports the benign neglect hypothesis and is robust to alternative model specifications, including controlling for victim gender and race. Implications for policy and theories in the conflict tradition are discussed.Item Haptic Listening: Analyzing Black Women’s Witnessing, Fugitivity, and Refusal in the 1990s and Early 2000s(2024) Young, Dominique; Avilez, GerShun; English Language and Literature; Digital Repository at the University of Maryland; University of Maryland (College Park, Md.)The 90s through early 2000s was an era marked by vociferous noises. This noise included Black popular cultural expansions in art, sonic waves of resistance via protests against police brutality, the crackling of arson fire expressing the Black community’s rage in response to anti-Blackness, and calls for reproductive justice for poor Black women among other sounds. While this era maintained the loudness of both prosperity and protest, it also nurtured quiet resistances against the U.S. carceral State. Specifically, Black women’s and girls’ vociferous and less discernible practices of refusal situated within film, literature, and music videos also propelled narrative resistance against the atmospheric violence of the State. What were the quiet and less discernible ways that Black women and girls challenged the U.S. carceral State during the 90s and in the early 2000s? What are the lenses or methodologies that make this resistance legible? What Black feminist scholars have already practiced the method of listening to that which is illegible or does not exist? What do Black girls and women gain when we can see their quiet refusal in this way? What is at stake if we cannot see this refusal? These are some of the questions that underscore this dissertation. In my dissertation I argue Black women and girls vociferously and quietly challenge the 1990s and early 2000s U.S. carceral State in film, fiction, and music videos. I maintain that the excavation of their less discernible (or “quiet”) practices of refusal within these cultural texts require a focused attention to detail and a counterintuitive practice of listening to that which is illegible, indiscernible, or hidden. In this way, Black popular culture is a site for the emergence and existence of resistance that brings to the forefront the efforts of Black women and girls who are often marginalized in resistance discourses. Drawing from Saidiya Hartman’s “Venus in Two Acts” and Tina Campt’s Listening to Images at the intersection of Haptic Media Studies, I use a framework—haptic listening—for discerning and excavating their practices of refusal that are illegible to cursory analyses. Following my introduction chapter, in chapter two I center my analysis on Leslie Harris’ film Just Another Girl on the I.R.T. (1992) and F. Gary Gray’s film Set It Off (1996). Through haptic listening, I trace a cartography of witnessing informed by Saidiya Hartman’s Scenes of Subjection, Dwight McBride’s Impossible Witnesses, and Angela Ards’ Words of Witness. I argue that specific instances of witnessing that reify Black women’s and girls’ subjection, fracture Black kinship, and disrupt Black futures are the catalysts for their resistance to the carceral State. In chapter three I examine protagonist Winter’s fugitive journey in Sister Souljah’s 1999 novel The Coldest Winter Ever. Drawing from Fred Moten’s Stolen Life, Katherine McKittrick’s Demonic Grounds, and Jennifer Nash’s “Black Maternal Aesthetics,” I argue that her fugitive journey begins and ends with her own vociferous haptic encounters—a process I call Circular Fugitivity. In the end, I trace a panoptic cartography that honors the emergence of her own political potential as she attempts to escape the grasp of the carceral State. And finally in chapter four I analyze the music video performances of Charli Baltimore in “Down Ass Chick” (2002) and Meagan Good in “21 Questions” (2003). Drawing from the work of Tina Campt in Listening to Images at the convergence of haptic media studies, I argue that their transformative practices of refusal are legible within and imbued by their identificatory photographs in each music video. These aesthetic practices of refusal, made obvious through haptic listening, appear throughout the music videos signaling the movement toward freedom. In the end, my project honors the less discernible practices of resistance by Black women and girls during the 1990s and early 2000s.Item ELECTROLYTE AND INTERFACE DESIGNATION FOR HIGH-PERFORMANCE SOLID-STATE LITHIUM METAL BATTERIES(2024) Zhang, Weiran; Wang, Chunsheng; Material Science and Engineering; Digital Repository at the University of Maryland; University of Maryland (College Park, Md.)The demand for advanced battery technology is intensifying as electric energy becomes the foundation of modern technologies, such as smart devices, transportation, and artificial intelligence. Batteries play a crucial role in meeting our increasing energy demands and transitioning towards cleaner and more sustainable energy sources. However, range anxiety and safety concerns still hinder the widespread application of battery technology.Current Li-ion batteries, based on graphite anode, have revolutionized battery technology but are nearing the energy density limits. This necessitates the development of metal batteries, employing lithium metal as anode which eliminates host materials that do not contribute to capacity, thereby offering 10 times higher specific capacity. Recent research on lithium metal batteries has seen a significant surge, with growing knowledge transitioning from Li+ intercalation chemistry (graphite) to Li metal plating/stripping. The electrolyte, which was previously regarded as an inert material and acting as a Li+ ion transportation mediator, has gradually attracted researchers’ attention due to its significant impact on the solid electrolyte interphase (SEI) and the Li metal plating/stripping behaviors. Compared to the traditional liquid electrolytes, solid-state lithium metal batteries (SSLMB) have been regarded as the holy grail, the future of electric vehicles (EVs), due to their high safety and potential for higher energy density. However, there are notable knowledge gaps between liquid electrolytes and solid-state electrolytes (SSEs). The transition from liquid-solid contact to solid-solid contact poses new challenges to the SSLMB. As a result, the development of SSLMB is strongly hindered by interface challenges, including not only the Li/SSE interfaces and SSE/cathode interfaces but also SSE/SSE interfaces. In this dissertation, I detailed our efforts to highlight the role of electrolytes and interfaces and establish our understanding and fundamental criteria for them. Building on this understanding, we propose effective and facile engineering solutions that significantly enhance batterie metrics to meet real-world application demand. Rather than simply introducing new compositions or new designations, we are dedicated to introducing our understanding and mechanism behind it, we hope the scientific understanding, the practical solution, and the applicability to various systems can further guide and inspire the electrolyte and interface designation for next-generation battery technology.Item Essays on Higher Education(2024) Montoya Agudelo, Alejandra; Urzúa, Sergio; Economics; Digital Repository at the University of Maryland; University of Maryland (College Park, Md.)In this dissertation, I quantify the impact of uncertainty on schooling postsecondary choices, study the returns to higher education degrees, and analyze the effects of policies that intend to reduce college education costs. In the second and third chapters, I employ structural Roy models and data from the National Longitudinal Survey of Youth 1997 to analyze postsecondary schooling decisions, focusing on four- and two-year college paths. These models have three sources of unobserved heterogeneity affecting earnings and decisions: cognitive, socioemotional, and mechanical latent abilities. The second chapter employs a dynamic Roy model to quantify the impact of uncertainty when making postsecondary schooling. While schooling choices maximize expected value, some individuals opt for alternatives that, in hindsight, do not yield the highest ex-post net value due to idiosyncratic shocks affecting earnings and schooling costs that are unknown when decisions are made. This uncertainty generates significant losses: I estimate that aggregate net value would increase by 11% if individuals had perfect foresight. Moreover, I study how decisions would change under perfect foresight and characterize individuals more likely to be affected by uncertainty. I also explore policy simulations to study the effects of an annual two-year college $16,500 subsidy, including the characterization of compliers—those more likely to attain a two-year college degree because of the subsidy. The third chapter analyzes the interplay of observed and unobserved dimensions as determinants of marginal treatment effect (MTEs) through decomposition analysis. We posit a static Roy model with unordered schooling choices. We focus on MTEs as they shape other treatment effects and capture the impact for those responding to minimal incentives. Additionally, we estimate the model separately for women and men, focusing on describing how responses and treatment effects vary between these two groups. We find different ability distributions and returns to ability for women and men. Moreover, we document how different observed characteristics and ability dimensions play different roles in determining the heterogeneity observed in MTEs across both groups. The last chapter investigates the impact of financial aid programs on high-quality private colleges' decisions, leveraging exogenous variation from a large-scale aid program in Colombia, where beneficiaries could only enroll at high-quality colleges. Using a difference-in-differences strategy and data for all private colleges in the country, we find that tuition increased by about 6.9 percent after the government launched the aid policy. We contribute to the literature by analyzing the effect of financial aid programs on tuition for high-quality universities and studying how universities might change other outcomes beyond tuition in response to the policy. We show universities hire more faculty members, keep the student-to-faculty constant, and open new undergraduate programs. Our findings support a narrative where prestigious colleges prioritize their reputation, opting for gradual expansion without compromising quality.