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 Mindreading for Cooperation: a moderately minimalist approach(2019) Schoenher, Julius; Carruthers, Peter; Philosophy; Digital Repository at the University of Maryland; University of Maryland (College Park, Md.)This dissertation puts forth a series of arguments about the extent to which human cooperative interaction is fundamentally shaped by mindreading; i.e. the capability to reason about the psychological causes (e.g. intentions, beliefs, goals) of behavior. The introduction to this dissertation discusses the broad philosophical underpinnings that lay the foundations for more specific philosophical issues under discussion in subsequent chapters. In chapter two, I argue that a thorough interpretation of the relevant empirical evidence suggests that mindreading is fast, effortlessly deployed, and operative sub-personally. For this reason, mindreading is principally well-suited to enable most everyday cooperative interactions. In the appendix, I (in collaboration with Evan Westra ) elaborate on this picture, arguing that the cognitive mechanisms operative in social interactions are, in all relevant respects, similar to those operative in non-interactive situations. While chapter two and the appendix defend the idea that the cognitive faculties responsible for mindreading are fit to enable cooperative interactions, chapters three and four take this perspective for granted and discusses whether human cooperation is crucially dependent on a form of reciprocal attribution of mental states that is often labeled common knowledge. In chapter three of this dissertation I address, and reject, the oft defended idea that truly performing an action together with others requires that all parties commonly know their intended goals. I argue that this view is fundamentally mistaken. Successfully acting together with others often requires not knowing these goals. Chapter four explores reciprocal belief attribution in the context of coordination problems. Humans often coordinate their actions by replicating successful past choices; they reason based on precedent. Philosophers have often claimed that solving coordination problems by relying on precedent presupposes common knowledge that all parties rely on precedent in trying to coordinate their actions. Chapter four points out that this assumption is erroneous: Coordinating behavior on the basis of precedent is broadly incompatible with any higher-order knowledge (or beliefs) about the other agents’ choices.Item Reasoning about Geometric Object Interactions in 3D for Manipulation Action Understanding(2019) Zampogiannis, Konstantinos; Aloimonos, Yiannis; Computer Science; Digital Repository at the University of Maryland; University of Maryland (College Park, Md.)In order to efficiently interact with human users, intelligent agents and autonomous systems need the ability of interpreting human actions. We focus our attention on manipulation actions, wherein an agent typically grasps an object and moves it, possibly altering its physical state. Agent-object and object-object interactions during a manipulation are a defining part of the performed action itself. In this thesis, we focus on extracting semantic cues, derived from geometric object interactions in 3D space during a manipulation, that are useful for action understanding at the cognitive level. First, we introduce a simple grounding model for the most common pairwise spatial relations between objects and investigate the descriptive power of their temporal evolution for action characterization. We propose a compact, abstract action descriptor that encodes the geometric object interactions during action execution, as captured by the spatial relation dynamics. Our experiments on a diverse dataset confirm both the validity and effectiveness of our spatial relation models and the discriminative power of our representation with respect to the underlying action semantics. Second, we model and detect lower level interactions, namely object contacts and separations, viewing them as topological scene changes within a dense motion estimation setting. In addition to improving motion estimation accuracy in the challenging case of motion boundaries induced by these events, our approach shows promising performance in the explicit detection and classification of the latter. Building upon dense motion estimation and using detected contact events as an attention mechanism, we propose a bottom-up pipeline for the guided segmentation and rigid motion extraction of manipulated objects. Finally, in addition to our methodological contributions, we introduce a new open-source software library for point cloud data processing, developed for the needs of this thesis, which aims at providing an easy to use, flexible, and efficient framework for the rapid development of performant software for a range of 3D perception tasks.Item Psychological and Neurobiological Outcomes of Parent-Child Adrenocortical Concordance(2017) Merwin, Stephanie; Dougherty, Lea R; Psychology; Digital Repository at the University of Maryland; University of Maryland (College Park, Md.)Emerging work has examined parent-child concordance of hypothalamic-pituitary-adrenal (HPA) axis functioning (i.e., adrenocortical concordance) which reflects the attunement or association of the stress hormone cortisol between the parent and child. The cortisol awakening response (CAR) is a critical aspect of HPA axis functioning that is sensitive to environmental factors and uniquely predicts psychopathology in youth. HPA axis functioning has also been linked to alterations in brain structure, specifically the hippocampus. The hippocampus is a critical brain region involved in learning and emotional processing and is sensitive to the parenting context, and undergoes change across early childhood. Despite these critical links between the parent-child dyad, HPA axis functioning, and hippocampal structure, no study has examined the longitudinal outcomes of adrenocortical concordance. The current study examined early parent-child adrenocortical concordance and its concurrent and longitudinal associations with parenting and children’s psychopathology and psychosocial functioning, as well as its longitudinal associations with children’s hippocampal structure in middle childhood. Participants included 142 parent-child dyads. Parents and children provided cortisol at Wave 1 when children were 3-5 years-old, and 98 dyads returned for the Wave 2 assessment three years later when children were 5-9 years-old. At Wave 1, parents and children provided salivary cortisol samples at waking, and 30 and 45 minutes post-waking across two days to assess the CAR. At Waves 1 and 2, child psychopathology and functioning were assessed through a parent-report clinical interview, and the parenting context was assessed through a laboratory-based parent-child interaction task. At Wave 2, a subsample of 51 children completed an anatomical magnetic resonance imaging assessment to measure hippocampal structure. Stronger parent-child concordance was associated with children’s poorer outcomes, namely increases in parental hostility from early to middle childhood, and children’s greater psychiatric symptoms and poorer psychosocial functioning in early and middle childhood. Moreover, parent- and child-level risk factors moderated several associations between stronger concordance and children’s poor outcomes. Parent-child concordance was not related to children’s hippocampal volumes in middle childhood. Importantly, our findings highlight adrenocortical concordance as a process underlying the parent-child relationship that plays a role in the development of psychopathology and functional impairment in children.Item DYNAMICS OF CAPSULES IN COMPLEX MICROFLUIDIC DEVICES(2018) Koolivand, Abdollah; Dimitrakopoulos, Panagiotis; Chemical Engineering; Digital Repository at the University of Maryland; University of Maryland (College Park, Md.)The dynamics of micro-capsules has attracted a lot of attention in the last decade due to their vast applications in different industrial sectors such as cosmetic products, food industry, chemical processes, reaction systems, cell modeling, drug delivery, and medical processes. Additionally, biological cells such as red blood cells can be modeled as capsules. Understanding the rheological behavior of these cells provides great physical insight for early diagnosis of relevant diseases. The main objective of this research is to investigate the effects of physical and geometrical parameters on the hydrodynamics of simple and multiple capsules in complex mi- crofluidic devices. For this purpose, we have developed the mathematical formulation needed for modeling multiple capsules with or without complex internal structures. The developed framework provides an enormous flexibility in problem definition, and facilitates the investigation of the hydrodynamics of a wide class of capsules in microfluidic channels and vascular capillaries. We first study the deformation of a spherical capsule in a T-junction channel. It is shown that an initially spherical capsule develops a bean shape at low flow rates and an inverse kayak shape at high flow rates. Based on the non-trivial deformation of the capsule, a new methodology for the determination of membrane moduli is proposed. For an accurate determination of the membrane moduli, it is paramount to measure the capsule dimensions precisely, which is easier in the proposed device owning to the stagnation-point flow of the T-junction. To determine the membrane moduli, one needs to do a single experiment for different flow rates, and compare the experimental measurements of the capsule steady-state dimensions with the provided computational data. We then consider the flow dynamics of non-spherical capsules and investi- gate the effects spheroidity and initial orientation on the steady-state shape. It is found that a non-spherical capsule, placed with a non-zero initial orientation angle along the centerline of a microchannel, does not practically rotate during deforma- tion. Thus, precise instrumentation is required for proper alignment of the capsule which influences the deformation and steady-state shape. This behavior may explain possible inconsistencies between measured (experimental) and calculated (compu- tational) shapes. We then study the lateral migration of capsules with different size in a mi- crofluidic channel with a trapezoidal cross-section. Owing to the emergence of 3D printing technology, fabrication of a channel with trapezoidal cross-section is fea- sible. Based on our computational data, we proposed an optimized geometry that could be utilized for separation of capsules or cells with different size. The main advantage of the proposed geometry is its inexpensive fabrication cost without the need for incorporating complicated inner structures, which automatically eliminates the risk of channel clogging. Moreover, the simple structure of the trapezoidal mi- crochannel allows an easy scale out through parallelization and reduction of the cell sorting time. In addition, we investigate the complex behavior of two (equal or unequal sized) capsules flowing in a square microfluidic channel. Capsules merging process controls the on-demand drug release and reaction. Thus, we identified the hydro- dynamic conditions that facilitates or hinders the merging of the capsules. The merging process is commonly accompanied by the drainage of existing liquid film between two particles. We observed that the capsules merging in most cases is ac- companied by the formation of dimple surfaces, and thus a simplified flat lubrication surface assumption which is widely-used in the theoretical studies might not be an ideal choice for modeling the film drainage time in merging process.Item Reimagining Ruins: Preserve | Utilize | Interact(2016) Olander, Danielle; Abrams, Michael; Architecture; Digital Repository at the University of Maryland; University of Maryland (College Park, Md.)This thesis will examine ways to preserve ruinous structures, utilize their aesthetics, and design an interactive intervention that weaves the old and new together in a seamless way. Ruinous structures should not be seen as an eye-sore to the image of the city. In fact, it is a reminder of all the things the city has faced in the past. This thesis analyzes different ways that previous designers have rehabilitated pre-existing structures. These methods are applied to each potential site in order to determine which typology would prove most fruitful. Site selection followed specific criteria. The first is that the structure could not be a complete building. Second, the site should be part of a community. And third, the structure should be located in an urban area. By the end of this journey, this thesis seeks awareness having pre-existing structures woven into new designs, and as an opportunity to inspire.Item Parental Hostility and Parent Stress Physiology: The Moderating Role of Child Effortful Control(2014) Merwin, Stephanie; Dougherty, Lea R.; Psychology; Digital Repository at the University of Maryland; University of Maryland (College Park, Md.)This study examined the moderating role of child effortful control on the association between observed parental hostility and parents' cortisol awakening response (CAR), a critical index of stress system functioning. Participants included 99 medication-free parents and their preschool-aged children. Parents obtained salivary cortisol samples at waking, 30, and 45 minutes post-waking and at bedtime across two consecutive days. Parental hostility was assessed during an observational parent-child interaction task, and child effortful control was assessed using parent report. Observed parental hostility was associated with parents' lower cortisol levels at 30 and 45 minutes post-waking and lower CAR. Low levels of child effortful control were associated with parents' lower bedtime cortisol. Moreover, results demonstrated an interaction effect between parenting and child behavior on parent CAR. The findings highlight the significance of continued examination of the neurobiology of parenting with a focus on the interactive effects between parenting and child behavior.Item The Neural Mechanisms Supporting Structure and Inter-Brain Connectivity In Natural Conversation(2014) AbdulSabur, Nuria; Idsardi, William; Neuroscience and Cognitive Science; Digital Repository at the University of Maryland; University of Maryland (College Park, Md.)Conversation is the height of human communication and social interaction, yet little is known about the neural mechanisms supporting it. To date, there have been no ecologically valid neuroimaging studies of conversation, and for good reason. Until recently, imaging techniques were hindered by artifact related to speech production. Now that we can circumvent this problem, I attempt to uncover the neural correlates of multiple aspects of conversation, including coordinating speaker change, the effect of conversation type (e.g. cooperative or argumentative) on inter-brain coupling, and the relationship between this coupling and social coherence. Pairs of individuals underwent simultaneous fMRI brain scans while they engaged in a series of unscripted conversations, for a total of 40 pairs (80 individuals). The first two studies in this dissertation lay a foundation by outlining brain regions supporting comprehension and production in both narrative and conversation - two aspects of discourse level communication. The subsequent studies focus on two unique features of conversation: alternating turns-at-talk and establishing inter-brain coherence through speech. The results show that at the moment of speaker change, both people are engaging attentional and mentalizing systems - which likely support orienting toward implicit cues signaling speaker change as well as anticipating the other person's intention to either begin or end his turn. Four networks were identified that are significantly predicted by a novel measure of social coherence; they include the posterior parietal cortex, medial prefrontal cortex, and right angular gyrus. Taken together, the findings reveal that natural conversation relies on multiple cognitive networks besides language to coordinate or enhance social interaction.Item A Meta-Analytical Test of Perceived Behavioral Control Interactions in the Theory of Planned Behavior(2013) Boudewyns, Vanessa; Fink, Edward L.; Communication; Digital Repository at the University of Maryland; University of Maryland (College Park, Md.)This study used meta-analytic procedures to test for interaction effects among the components of the theory of planned behavior (TPB). The central hypothesis examined was that attitudes and subjective norms should perform less well in explaining intentions when perceptions of behavioral control are low. A traditional meta-analysis of nine studies that directly examined perceived behavioral control (PBC) interactions was conducted. A second meta-analysis--the main focus of this dissertation--was conducted that tested for two- and three-way interactions in which the presence of PBC interactions was investigated in 121 studies, which provided 154 data sets with 44,424 participants. In addition to testing for two-way PBC interactions, this meta-analysis also examined whether the presence of PBC interactions depended on other variables. Specifically, three-way interactions with type of behavior classification (i.e., public versus private, familiar versus unfamiliar) and type of PBC operationalization (e.g., self-efficacy, perceived difficulty, perceived control, or some combination of the three) were explored. Results indicated that attitude by PBC interactions exist but that the effects vary depending on the type of PBC operationalization and behavior context. In addition, meta-analytic structural equation modeling was used to examine whether the association between PBC and intention is mediated by attitude and subjective norms; however, no evidence for this relationship was found. Finally, results from an auxiliary analysis revealed that the attitude by PBC interaction on intention had statistically significant nonlinear effects in addition to a linear effect. In contrast, the norm by PBC interaction did not have statistically significant linear or nonlinear effects. The discussion highlights the effects of different meta-analytic techniques, the need for future investigation using experimental designs, the implications of these findings for further theory development, and practical implications for health communication researchers. In sum, through the use of a multi-faceted approach to quantitatively review attitude by perceived control and norm by perceived control interactions in the TPB, this study helped to address inconclusive results with regard to the existence and type of PBC interactions.Item DEVELOPMENT OF TOOLS TO CHARACTERIZE PROTEIN-PROTEIN INTERACTIONS(2010) Jiang, Jiangsong; Li, Shuwei; Stewart, Richard; Cell Biology & Molecular Genetics; Digital Repository at the University of Maryland; University of Maryland (College Park, Md.)Protein-protein interactions (PPIs) are crucial to most biological processes and activities. Large-scale PPI screening has been applied to model organisms as well as to human cells. Two approaches have been used extensively in high-throughput PPI studies: (i) the Yeast Two-Hybrid (Y2H) assay (a bottom-up method), and (ii) the tandem affinity purification (TAP) (a top-down method). However, a close examination of both techniques revealed issues that limit their effectiveness. Thus, it is important to develop new methods that can bridge the gap between the Y2H and the TAP. In this thesis, two approaches were developed to meet this need. The first approach was a photoaffinity labeling tool, which was based on a photo-caged reactive intermediate para-quinone methide (pQM) to study protein-peptide associations. This system was developed and optimized by using the interaction between catPTP1Bm and the EGFR peptide as a test case. Highly specific protein labeling was achieved, and mass spectrometry (MS) was used to identify the crosslinked site on the target protein. Interestingly, two peptides from catPTP1Bm detected by MS were found close to the enzyme-substrate binding interface in the three-dimensional structure of the complex, which demonstrated this method might be useful for the analysis of protein complex conformation. The second approach, named "PCA plus", took advantage of a technique referred to as "Protein-fragment Complementation Assay (PCA)". A hydrolysis-deficient mutant β-lactamase (E166N) was used, which enabled interacting protein labeling in live cells. With this modification, the PCA plus method realized live cell imaging with subcellular resolution. Fluorescent microscopy and flow cytometry analysis demonstrated its potential applications. In addition, a new β-lactamase substrate was developed for the PCA plus method and was applied to enable purification, from living cells, of prey protein interacting with a bait protein. The observed enrichment of interacting partners suggested the system could be used for high-throughput PPI screening. Moreover, this method could also be useful for the characterization of low affinity and transient PPIs because of its capacity on labeling interacting protein inside cells.Item An examination of the relationship between students' interaction with host nationals while on study abroad and their development of intercultural sensitivity(2004-05-12) Armfield, Patricia Anne; Komives, Susan R.; Counseling and Personnel ServicesThis study examined the relationship between students' interactions with host nationals while on study abroad and their development of intercultural sensitivity. The theoretical base was drawn from Allport's (1954) contact hypothesis. The researcher used the Intercultural Sensitivity Scale (Chen & Starosta, 2000), items revised from previous studies concerning interaction with difference, and demographic items. The sample consisted of 60 undergraduate students who had returned to the University of Maryland from a Fall 2003 semester abroad. Regression results found a significant increase in students' level of intercultural sensitivity prior to participating in study abroad and their level upon their return. The results are limited by low response rates. No significant relationship was found between the students' interactions with host nationals as measured in this study and their development of intercultural sensitivity. Future research is needed to further apply and operationalize Allport's (1954) contact hypothesis.