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 EFFECTS OF THREATS TO GROUPS ON INGROUP-PROSOCIAL BEHAVIORS AND ORIENTATIONS(2017) Kerns, Kristin; Lucas, Jeffrey W; Sociology; Digital Repository at the University of Maryland; University of Maryland (College Park, Md.)This research investigates how threats to people’s ingroups promote ways of thinking and behaving that benefit these groups (ingroup prosociality). Drawing on terror management theory and other relevant literature, I propose that threats promote ingroup prosociality, and that threats play an important role in explaining why members of collectivistic societies (e.g., Eastern) tend to exhibit more ingroup prosociality than members of individualistic societies (e.g., Western). Three experimental studies isolated effects of threats on outcomes I propose reflect ingroup prosociality: holistic versus analytic types of cognitive and social orientations (Study 1), upholding status orders in groups (Study 2), and promoting the legitimacy of power in groups (Study 3). To experimentally manipulate threat, participants wrote about either a threatening or non-threatening situation. In the group studies (2 and 3), the threat situation was also part of the task itself. Study 1 provides some support for increased ingroup prosociality when threatened, and some evidence for differences by culture and type of threat. Though results generally suggest that Americans respond more ingroup prosocially than Indians, they do not provide compelling evidence of consistent cross-cultural patterns as predicted. Study 2 provides only minimal support for threat increasing adherence to status orders. Study 3 provides a great deal of support for threat increasing promotion of the legitimacy of power structures, and results suggest especially strong responses among high-status participants with low-status partners. For each study, I also address some results in the opposite direction predicted. Taken together, the results only somewhat support my proposed ingroup prosociality worldview theory. Alternatively, patterns in results suggest that threatened ingroup members may be motivated to preserve their self-esteem and reduce their anxiety. Though this self-serving explanation is consistent with terror management theory, it is not consistent with the ingroup prosociality worldview initially proposed. Overall, the results provide evidence that threat (1) affects both behaviors and orientations (many proposed to reflect ingroup prosociality), which warrant consideration together as defensive responses to threats, and (2) increases promoting the legitimacy of power based on status in some situations. I discuss limitations, implications for theory and potential leadership interventions, and directions for future work.Item An Octahedral Tiling on the Ideal Boundary of the Complex Hyperbolic Plane(2006-08-02) Pelzer, Blake Patrick; Schwartz, Richard E; Mathematics; Digital Repository at the University of Maryland; University of Maryland (College Park, Md.)We present an octahedral tiling on the ideal boundary of the complex hyperbolic plane. The tiling was discovered through the use of a program we wrote called CHAT. We show visual evidence of this tiling and prove some results about embedding a specific tile.Item A Study of Social Interaction and Teamwork in Reformed Physics Laboratories(2006-02-21) Gresser, Paul William; Redish, Edward F.; Physics; Digital Repository at the University of Maryland; University of Maryland (College Park, Md.)It is widely accepted that, for many students, learning can be accomplished most effectively through social interaction with peers, and there have been many successes in using the group environment to improve learning in a variety of classroom settings. What is not well understood, however, are the dynamics of student groups, specifically how the students collectively apprehend the subject matter and share the mental workload. This research examines recent developments of theoretical tools for describing the cognitive states of individual students: associational patterns such as epistemic games and cultural structures such as epistemological framing. Observing small group interaction in authentic classroom situations (labs, tutorials, problem solving) suggests that these tools could be effective in describing these interactions. Though conventional wisdom tells us that groups may succeed where individuals fail, there are many reasons why group work may also run into difficulties, such as a lack or imbalance of knowledge, an inappropriate mix of learning styles, or a destructive power arrangement. This research explores whether or not inconsistent epistemological framing among group members can also be a cause of group failure. Case studies of group interaction in the laboratory reveal evidence of successful groups employing common framing, and unsuccessful groups failing from lack of a shared frame. This study was conducted in a large introductory algebra-based physics course at the University of Maryland, College Park, in a laboratory designed specifically to foster increased student interaction and cooperation. Videotape studies of this environment reveal that productive lab groups coordinate their efforts through a number of locally coherent knowledge-building activities, which are described through the framework of epistemic games. The existence of these epistemic games makes it possible for many students to participate in cognitive activities without a complete shared understanding of the specific activity's goal. Also examined is the role that social interaction plays in initiating, negotiating, and carrying out these epistemic games. This behavior is illustrated through the model of distributed cognition. An attempt is made to analyze this group activity using Tuckman's stage model, which is a prominent description of group development within educational psychology. However, the shortcomings of this model in dealing with specific cognitive tasks lead us to seek another explanation. The model used in this research seeks to expand existing cognitive tools into the realm of social interaction. In doing so, we can see that successful groups approach tasks in the lab by negotiating a shared frame of understanding. Using the findings from these case studies, recommendations are made concerning the teaching of introductory physics laboratory courses.Item Biologically-inspired optimal control(2005-11-14) Shao, Cheng; Hristu, Dimitrios; Mechanical Engineering; Digital Repository at the University of Maryland; University of Maryland (College Park, Md.)Inspired by the collective activities of ant colonies, and by their ability to gradually optimize their foraging trails, this dissertation investigates the cooperative solution of a broad class of trajectory optimization problems with various types of boundary conditions. A set of cooperative control algorithms are presented and proved to converge to an optimal solution by iteratively optimizing an initially feasible trajectory/control pair. The proposed algorithms organize a group of identical control systems by imposing a type of pair-wise interaction known as "local pursuit". The bio-inspired approach taken here requires only short-range, limited interactions between group members, avoids the need for a "global map" of the environment in which the group evolves, and solves an optimal control problem in "small" pieces, in a manner which is made precise. These features enable the application of the proposed algorithms in numerical optimization, leading to an increase of the permitting size of problems that can be solved, as well as a decrease of numerical errors incurred in ill-conditioned problems. The algorithms' effectiveness is illustrated in a series of simulations and laboratory experiments