UMD Theses and Dissertations
Permanent URI for this collectionhttp://hdl.handle.net/1903/3
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.
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Item Understanding the Unthinkable: A Comparative Analysis of Mass Shooters, Homicide Offenders, and Violent Extremists Using Criminological Theory(2024) Yanez, Yesenia A.; LaFree, Gary; Criminology and Criminal Justice; Digital Repository at the University of Maryland; University of Maryland (College Park, Md.)As mass shootings continue, the need for more theoretically driven solutions grows. Criminologists can offer tremendous insight, though they should be wary of applying existing theories to this relatively new phenomenon. In this dissertation, I explore how mass shootings fit into our understanding of crime and violence. I begin by describing mass shooter demographics and motives over time. I then compare mass shooters to homicide offenders and violent extremists. Focusing on social control and general strain variables, I find that mass shooters are significantly different than single-victim homicide offenders in terms of common correlates of crime. Mass shooters and violent extremists, on the other hand, show fewer differences and greater definitional overlap. Finally, I consider how mass shooting definitions shape our perception of mass shooters. Considering these results, I conclude that a mass shooter’s path to violence does not resemble that of a common homicide offender but rather one of a violent extremist. Future scholars can thus reimagine existing criminological theories to help explain mass shootings and provide solutions that are more appropriate.Item Disorder, Dissatisfaction with the Neighborhood, and Delinquency(2018) Goodier, Michael; Porter, Lauren; Criminology and Criminal Justice; Digital Repository at the University of Maryland; University of Maryland (College Park, Md.)This study examines the association between neighborhood dissatisfaction and adolescent delinquency. The objectives of this project are to determine (1) whether neighborhood disorder is related to delinquency among adolescents (2) whether adolescents who report increased levels of neighborhood dissatisfaction are relatively more involved in delinquency than their peers, (3) if neighborhood dissatisfaction is especially related to two types of delinquency implicated by strain theory, violence and substance abuse, and (4) if neighborhood dissatisfaction weakens any of the association between neighborhood disorder and crime. Applying stepwise logistical regression, I find little support for the association between disorder and adolescent offending and no association between neighborhood dissatisfaction with either violence or substance abuse when compared to the likelihood of engaging in instrumental crime. These findings raise questions regarding the relationship between disorder and individual levels of delinquency as well as the relationship between disorder and neighborhood dissatisfaction among adolescents.Item Analysis of the Effects of Non-Supine Sleeping Positions on the Stress, Strain, Deformation and Intraocular Pressure of the Human Eye(2014) Volpe, Peter; Flatau, Alison B; Aerospace Engineering; Digital Repository at the University of Maryland; University of Maryland (College Park, Md.)This thesis presents analytical models, finite element models and experimental data to investigate the response of the human eye to loads that can be experienced when in a non-supine sleeping position. The hypothesis being investigated is that non-supine sleeping positions can lead to stress, strain and deformation of the eye as well as changes in intraocular pressure (IOP) that may exacerbate vision loss in individuals who have glaucoma. To investigate the quasi-static changes in stress and internal pressure, a Fluid-Structure Interaction simulation was performed on an axisymmetrical model of an eye. Common Aerospace Engineering methods for analyzing pressure vessels and hyperelastic structural walls are applied to developing a suitable model. The quasi-static pressure increase was used in an iterative code to analyze changes in IOP over time.Item The Moderating Role of Negative Emotionality, Positive Emotionality, and Low Constraint on the Relationship between Strain and Criminal Behavior(2013) Foriest, Whytnee; Gottfredson, Denise C; Criminology and Criminal Justice; Digital Repository at the University of Maryland; University of Maryland (College Park, Md.)General strain theory (GST) posits that strain causes crime (Agnew et al., 1992). Individuals who fail to achieve positively valued goals, lose positively valued stimuli, or are presented with negative stimuli are more likely to engage in criminal behavior. GST, however, acknowledges that individuals vary in their responses to strain and not all strained individuals turn to crime. Agnew et al. (2002) proposed a number of factors that may increase the likelihood of a criminogenic response to strain. Of these, he considers personality traits to be among the most important (Agnew, 2006). This study examines the moderating role of negative emotionality, low constraint, and positive emotionality on the relationship between strain and criminal behavior. Findings reveal a direct, positive association between strain and crime, but there was no support for the conditioning hypotheses proposed in this study.Item RESPONSE OF PREMIXED HYDROCARBON FLAMES WITH AND WITHOUT HYDROGEN ADDITION TO STEADY AND OSCILLATORY STRAIN RATES(2005-11-16) Plaia, Joseph; Jackson, Gregory; Mechanical Engineering; Digital Repository at the University of Maryland; University of Maryland (College Park, Md.)The response to steady-state and oscillatory strain rates of lean, premixed hydrocarbon-air flames with and without H2 doping has been investigated analytically, numerically and experimentally. The analytical analysis provides a theoretical framework for assessing steady-state flame temperature (Tflame) response to strain rate as a function of reactant composition, through Lewis numbers (Lek), and of non-dimensional stretch defined by the Karlovitz number (Ka). An integral analysis with discrete reaction zones for each fuel has been developed, capturing the linear response of Tflame to Ka (<0.2) for steady-state CH4-H2 and C3H8-H2 lean flames as predicted by numerical models using full chemistry (GRI-Mech V3.0). This method improves predictions from single-flame zone integral analyses. Detailed transient numerical simulations using GRI-Mech V3.0 determined the effects of H2 addition on CH4 premixed flame responses to strain oscillations. Symmetric velocity (pressure) oscillations in an opposed jet counterflow configuration were simulated for frequencies, f, ranging from 100 to 1000Hz, focusing on behavior at large Ka, near extinction. The oscillations cause flame characteristics (e.g. species mass fractions and Tflame) to vary significantly from steady-state responses. While flame responses to 100Hz oscillations closely follow quasi-steady behavior, responses for f>200Hz deviate, with phase lags and different amplitudes, from quasi-steady predictions. At f=1000Hz, the flame acts as a low pass filter, reducing amplitudes in property oscillations compared to quasi-steady analysis. For the higher frequencies, predictions indicate premixed flames can persist momentarily beyond steady-state extinction strain rate limits during oscillations. Strain rate oscillation amplitudes required to extinguish flames, Aext, are determined numerically with the computational model and compared with experimental measurements. Simulations show that Aext increases with f due to attenuated flame response for f>200Hz. Increasing flame equivalence ratio, , and/or percentage of O2 consumed by H2, , increases reaction rates, decreasing the deviation from quasi-steady behavior and reducing the relative Aext. Counterflow premixed flame experiments with upstream speaker-imposed oscillations are also used to evaluate Aext. Phase-locked velocity measurements (with laser Doppler anemometry) assist in understanding how upstream pressure oscillations translate into velocity field (strain rate) oscillations. Measured Aext values validated trends in the computational results.