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  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
331

Victimization, Cultural Identity, and Delinquency: Extending an Integrated General Strain Theory to Native American Youth

Phelan, Korey Shawn 01 January 2019 (has links)
As a group, Native American youth have elevated rates of delinquency and substance use. However, research specifically examining the etiology of delinquency among Native American youth is sparse. In order to fill this gap, this study utilized a general strain theory (GST) framework integrated with feminist criminological insights and an indigenist stress-coping model (ISCM) to examine the impact of victimization as a source of strain (i.e., interpersonal victimization, sexual assault, and peer assault) on delinquent outcomes (i.e., violent and property delinquency, alcohol and marijuana use) among a sample of Native American youth attending school (and likely residing) on or near Indian reservations. This study utilized secondary data from the third wave of the Drug Use Among Young American Indians: Epidemiology and Prediction: 1993-2006 and 2009-2013 study (N = 2,457). Partial proportional odds (PPO) models were estimated to examine the potential non-linear effects of victimization on delinquency while ordinary least squares (OLS) regression models were estimated to test the mediation and moderation hypotheses within GST. Models were estimated for the total sample and for males and females separately to assess for gender differences in GST processes. Special attention was paid to the role of Native American cultural identity as a moderator in the strain - delinquency relationship. Results indicate mixed support for hypotheses drawn from GST.
332

CHILD ABUSE AND NEGLECT: GENERAL STRAIN AND PROSOCIAL COPING THROUGH EMPLOYMENT

Berner, Rachel S 01 August 2019 (has links)
This thesis explores the idea that those who have childhood victimization through abuse may be more likely to go into professions that directly help others as adults. This idea comes from Agnew's general strain theory and is an example of positive coping and prosocial coping. Coping is the response necessary when strains are introduced to an individual. They may be positive or negative. Prosocial coping is an individual using their coping mechanisms to help themselves by helping others in their community. This thesis uses data from the “National Longitudinal Study of Adolescent to Adult Health (Add Health), 1994-2008" Harris and Udry, North Carolina Chapel Hill. Questions about abuse and employment are coded and run through statistical analysis. These analyses are independent sample t-tests binary regression models. Findings are discussed and further research in this area is suggested.
333

Strain Accommodation, Metamorphic Evolution, And 3d Kinematics Of Transpressional Flow Within The Lower Crust Of A Cretaceous Magmatic Arc In Fiordland, New Zealand

Moyer, Griffin Amoss 01 January 2019 (has links)
The George Sound Shear Zone (GSSZ) exposed in Bligh Sound within Fiordland, New Zealand allowed us to reconstruct the kinematics of transpressive flow in >100 km2 of exhumed Cretaceous lower crust. We compare the three-dimensional characteristics of the deformation to theoretical models of transpression that assume steady-state flow in a homogeneous medium. This assumption is rarely the case for shear zones that experience metamorphism during deformation. We determined the three-dimensional kinematics of the GSSZ and evaluated the effects of metamorphism on strain accommodation and structural fabric evolution in the GSSZ to determine if metamorphism is an important parameter that transpressional models should account for. We found that metamorphism aided strain localization within the GSSZ and resulted in a style of structural fabric development that deviates from predictions made by theoretical models. We used foliation and lineation orientation data and field observations to determine GSSZ kinematics. Asymmetric pyroxene σ-porphyroclasts and hornblende fish show top-down-to-the-SW apparent normal shear sense with a sinistral component. The Z-axes of oblate SPO ellipsoids define the vorticity normal section and the moderately WNW-plunging vorticity vector. Foliation deflections relative to the shear zone boundaries yielded a vorticity magnitude (Wk) of ≥0.8. Our kinematic results suggest that the GSSZ records inclined, triclinic transpression with sinistral, top-down-to-the-SW simple shear-dominated flow. We used finite strain analysis and petrographic analysis to determine that metamorphism influences strain accommodation. Finite strain analyses were performed in 3D on 16 samples using the Rf/ɸ, Fry, and Intercept methods to determine the SPO fabric ellipsoids at different stages of deformation. Petrographic analysis was performed to identify metamorphic reactions using syn-kinematic minerals and constrain deformational temperatures using deformation mechanisms of plagioclase. Early deformation formed a ~13 km wide prolate fabric at granulite facies. Deformation later localized into a ~2-4.6 km wide oblate, mylonitic fabric at upper amphibolite facies. This fabric cross-cuts the prolate fabric and is characterized by metamorphic hornblende and biotite produced from retrogressive hydration reactions. Samples with syn-kinematic biotite contain more shear bands and display more grain size reduction of plagioclase than samples without this phase, suggesting these samples may have accommodated more strain. Changes in syn-kinematic metamorphic minerals were accompanied by steepening of stretching lineations and by changes in foliation orientation. Our analyses show that retrogressive hydration metamorphism aided strain localization within a cross-cutting oblate fabric, and the uneven distribution of biotite within this domain potentially influenced along strike variation in strain magnitude and fabric ellipsoid symmetry. Our results highlight the influence of fluid-induced metamorphism on shear zone evolution and call for new transpressional models to incorporate changes in rheology due to syn-kinematic metamorphism.
334

Cadmium and copper biosorption by a bacterial strain isolated from South Africa Antimony mine

Sekhula, Koena Sinah January 2010 (has links)
Thesis (Ph.D. (Biochemistry)) --University of Limpopo, 2010 / A heavy-metal resistant bacterium (GM 16) was isolated from a South African antimony mine, and the non-viable cells of the isolate were used to investigate its biosorption capacity for Cd(II) and Cu(II) from aqueous solution in a batch process. The biosorption of both metals were found to be influenced by factors such as pH of the metal solution, initial metal ion and biomass concentrations, rate of agitation, presence of other metal ions, contact time of the metal solution with the biomass and temperature. The initial biosorption of both Cd(II) and Cu(II) was rapid and equilibrium was reached within 1 hour of biomass contact with the metal solutions. The sorption of both metal ions was higher in weak acid than in strong acid conditions and the optimum pH values for Cd(II) and Cu(II) biosorption were 7 and 6, respectively. The presence of the other metal ions in the metal adsorption media influenced the biosorption of both Cd(II) and Cu(II). Mg2+ ions decreased the uptake of Cu(II) and Cd(II) by 4.7 and 6.5 %, respectively. Whereas K+, Na+ and Ca2+ ions increased the uptake of Cd(II) by 12.3, 8.7, and 3.2 %, respectively, they slightly decreased the sorption Cu(II) (2-6.4 %). Increases in initial metal ion (40-120 mg L-1) and biomass (0.8-4.8 g L-1) concentrations enhanced the sorption of Cd(II) and Cu(II) by GM16 biomass. When the biomass concentration was increased from 0.8 to 4.8 g L-1, the biosorption capacity of Cd(II) increased from 5.5 to 14.5 mg g-1 while that of Cu(II) increased from 2.8 to 14.7 mg g-1 at optimum pHs and a temperature of 40 °C. Maximum adsorption of both metals occurred at an agitation rate of 100 rpm. In addition, increase in initial metal ion concentration from 40-120 mg L-1 increased the initial adsorption rates (h) and the equilibrium metal sorption capacity (qe) of the GM 16 biomass from 6.07 to 16.51 mg g-1 for Cu(II) and 8.9 to 17.9 mg g g-1 for Cd(II). Adsorption equilibrium data for both metal ions fitted well to the Langmuir adsorption model with high correlation coefficients (r2 > 0.90) but the data for Cu(II) could also be described by the Freundlich adsorption model. Increase in temperature from 25-40 °C only caused marginal increases in maximum metal sorption capacities (qmax). The results on kinetic analysis showed that the biosorption processes of Cd(II) and Cu(II) ions by the non-viable GM 16 cells followed pseudo-second order kinetic model betterthan the pseudo-first order model, although the calculated metal sorption capacities obtained with the model were overestimated. The calculated thermodynamic parameters showed that the biosorption of Cd(II) and Cu(II) ions was feasible, spontaneous and slightly endothermic for Cd(II) but slightly exothermic for Cu(II) under examined conditions. Based on 16S ribosomal DNA sequencing, the bacterial isolate (GM 16) was identified as a Bacillus sp. and is closely related to Bacillus thuringiensis and Bacillus cereus strains. The biosorption capacity of the non-viable GM 16 biomass was higher than the biosorption capacity reported for the viable GM 16 cells, 65 % of Cd(II) was removed by non-viable biomass whereas 48 % was removed by the viable biomass. For the biosorption of Cu(II), the % metal ion adsorbed for the non-viable GM 16 cells was slightly higher than the % adsorbed for the viable cells although not statistically significant. Only 67 % of Cu(II) was removed by the non-viable cells whereas 65 % was removed by the viable cells. / National Research Foundation
335

The role of viral strain in a congenital brain infection

Plume, Jeffrey Michael 01 July 2015 (has links)
Lymphocytic Choriomeningitis Virus (LCMV) is a common arenavirus and natural murine pathogen that causes congenital neurodevelopmental disease in humans. Exposure to the virus in utero often results in severe and permanent damage the fetal brain and eyes. While usually severe, symptoms vary from case to case. Little is known about the pathological mechanism of congenital LCMV disease. Animal models of congenital LCMV infections suggest that timing of infection during gestation may influence disease outcomes; however, time alone cannot explain all of the variation observed in humans. Another possibility is that individuals are infected with different strains of LCMV. The LCMV genome is composed of four highly conserved genes, yet even single amino acid mutations can cause the virus to exhibit very different properties in animal models. However, the role of viral strain in the context of neurodevelopment remains relatively unexplored. Here, using a rat model of congenital LCMV infection, we demonstrate that three related strains of LCMV produce different patterns of infection and disease states. Infection with the highly neurotropic E350 strain induces a disease comparable to that observed in many confirmed cases of human congenital LCMV infection. While most of these animals survive to adulthood, they suffer permanent motor and behavioral abnormalities. Postmortem analyses of infected brains suggest that this strain has a proclivity for infecting mitotically active regions of the brain, including the cerebellum, olfactory bulb, hippocampus and subventricular region. E350 is not known to induce immunosuppression and viral clearance is likely mediated by a robust T-cell response. Indeed, we find high numbers of inflammatory cells in the brains of E350 animals and elevated pro-inflammatory cytokines and chemokines. The immune response, though responsible for the clearance of the virus from the brain, is also implicated in severe and sometimes permanent brain damage. The Clone 13 strain, a strain typically associated with lymphatic tissue, readily infects the brains of developing rats. Many of these animals do not live to adulthood. Those that survive exhibit extreme stunted growth, but relatively normal neurodevelopment and little discernable neurological disease. By adulthood, the brains of these animals are comparable in size and structure to controls, despite reduced body mass. The Clone 13 infects the same brain regions as the E350, but is not cleared and remained at high titers for the duration of the study. Chronic infection is likely a consequence of the immunosuppressive effects of Clone 13 on the host immune system. The WE2.2 causes a severe disease with both neurological and systemic symptoms. These animals exhibit persistent seizure like discharges during peak infection and significant motor deficits. They all fail to thrive, losing weight shortly after infection and die invariably 9-11 days post-inoculation. The brains of WE2.2 animals exhibit widespread infection of neurons in the cerebellum, hippocampus, olfactory bulbs, and cortex. WE2.2 does not cause immunosuppression and high levels of inflammatory cells are observed in the brain. Cytokine and chemokine expression is complex, without discernible trends and variable by brain region. Finally, we looked at alpha-dystroglycan (α-DG) expression in the brain and compared it with infectivity among the strains. Alpha-dystroglycan is recognized as the principle receptor for LCMV and due to mutations in the viral glycoprotein, certain strains are more dependent on α-DG for infection. Several associations between α-DG expression and viral infectivity were observed; however α-DG expression alone could not explain all the differences in infection patterns.
336

Self-efficacy, conventional cognitive coping, and the strain-delinquency relationship: A test of general strain theory

Ruppert, Michaela Siobhan 01 January 2014 (has links)
Agnew's (1992) general strain theory (GST) provides a framework for understanding individual and social factors that influence juvenile delinquency. Given the breadth of ideas encompassed by GST, tests typically focus on particular elements rather than testing the theory as a whole. Studies have provided a great deal of support for many of the core tenets of GST (e.g., Agnew and White 1992), while failing to produce conclusive support for others (e.g., Paternoster and Mazerolle 1994). Specifically, Agnew (1992) argues that the relationship between strain and delinquency is conditional, although research regarding what factors and through what mechanisms these factors shape the relationship is not conclusive. This project studies particular forms of strain -- noxious peer relationships and bullying victimization -- as well as tests the conditioning effects of self-efficacy within the strain-delinquency relationship. Self-efficacy is defined as one's personal evaluation of their ability to produce desired outcomes in a given situation (Bandura 1987, 1997). Agnew (1992) suggests self-efficacy is a coping resource that will condition the relationship between strain and delinquency. It is hypothesized that variations in self-efficacy will translate to differences in selected methods for coping and engagement in conventional coping adaptations to strain. I test the relationship between various forms of strain, self-efficacy and delinquency using two distinct data sets and methodologies. Findings from cross-sectional and longitudinal analyses indicate noxious peer relationships and bullying victimization are both positively related to delinquency. The theoretical implications surrounding the importance of self-efficacy as a coping resource, which promote conventional cognitive coping, are highlighted. But, indirect tests suggest this idea is not supported. In this research, self-efficacy does not moderate the relationship between strain and delinquency in the expected manner. Across methods and measures, strain and self-efficacy influence delinquency independent of each other. The dissertation concludes with a discussion of future research possibilities and policy implications.
337

Strains of skin tone bias: implications for adolescent delinquency and residential segregation for blacks

White, Karletta 01 May 2016 (has links)
In two separate studies, I examine the relationship between skin tone and important psychological well-being, delinquency, and social integration outcomes for Blacks, testing not only if skin tone is important in determining these outcomes but attempting to disentangle the mechanism by which the inequality is produced. More specifically, using data from the National Longitudinal Study of Adolescent to Adult Health (Add Health), in study one I draw on important propositions of Agnew’s (1992) General Strain Theory to investigate the extent to which darker skin impacts youths’ feelings of strain, psychological well-being, and delinquency. The study found skin tone to be significantly associated with certain facets of well-being but surprisingly there were no direct effects on various types of strain. Skin tone is a strong predictor of one’s involvement in serious weapon violence, controlling for prior delinquency. Results also show that skin tone matters more for female adolescents’ odds of being suspended compared to their male counterparts, while certain forms of strain significantly impact the effect of skin tone on one’s involvement in delinquent activity. In study two, I continue my investigation of skin tone as an external or interracial source of discrimination using the National Survey of American Life (NSAL). In this study I am concerned with whether Blacks with darker skin tones are more likely than their lighter-skinned counter parts to live in neighborhoods that they perceive as more segregated and with fewer amenities and community resources. Although these data did not allow me to directly test how the respondents came to reside in their present community (i.e. racial steering or neighborhood choice), I examine skin tone discrimination as well as major types of everyday discrimination (e.g. being denied a bank loan or housing opportunity) experiences reported by Blacks. Overall, findings suggest that darker-skinned Blacks fare worse in regard to frequent experiences of skin tone discrimination from Whites. Skin tone is significantly related to respondent’s perceived seriousness of drug activity in their current neighborhood, suggesting that skin tone may have some impact on one’s perceived neighborhood quality. Further results, implications, and conclusions are discussed.
338

Thermo-Mechanical Reliability of Micro-Interconnects in Three-Dimensional Integrated Circuits: Modeling and Simulation

Rodriguez, Omar 01 May 2010 (has links)
Three-dimensional integrated circuits (3D ICs) have been designed with the purpose of achieving higher communication speed by reducing the interconnect length between integrated circuits, and integrating heterogeneous functions into one single package, among other advantages. As a growing, new technology, researchers are still studying the different parameters that impact the overall lifetime of such packages in order to ensure the customer receives reliable end products. This study focused on the effect of four design parameters on the lifetime of the interconnects and, in particular, solder balls and through-silicon vias (TSVs). These parameters included TSV pitch, TSV diameter, underfill stiffness and underfill thickness. A three-dimensional finite element model of a 3D IC package was built in ANSYS to analyze the effect of these parameters under thermo-mechanical cyclic loading. The stresses and damage in the interconnects of the IC were evaluated using Coffin-Manson and the energy partitioning fatigue damage models. A three-level Taguchi design of experiment method was utilized to evaluate the effect of each parameter. Minitab software was used to assess the main effects of the selected design parameters. Locations of maximum stresses and possible damage initiation were discussed, and recommendations were made to the manufacturer for package optimization. Due to the very small scale of the interconnects, conducting mechanical tests and measuring strains in small microscopic scale material is very complicated and challenging; therefore, it is very difficult to validate finite element and analytical analysis of stress and strain in microelectronic devices. At the next step of this work, a new device and method were proposed to facilitate testing and strain measurements of material at microscopic scale. This new micro-electromechanical system (MEMS) consisted of two piezoelectric members that were constrained by a rigid frame and that sandwiched the test material. These two piezoelectric members act as load cell and strain measurement sensors. As the voltage is applied to the first member, it induces a force to the specimen and deforms it, which in turn deforms the second piezoelectric member. The second piezoelectric member induces an output voltage that is proportional to its deformation. Therefore, the strain and stresses in the test material can be determined by knowing the mechanical characteristics of the piezoelectric members. Advantages of the proposed system include ease of use, particularly at microscopic scale, adaptability to measure the strain of different materials, and flexibility to measure the modulus of elasticity for an unknown material. An analytical analysis of the device and method was presented, and the finite element simulation of the device was accomplished. The results were compared and discussed. An inelastic specimen was also analyzed and sensitivity of the device to detecting nonlinear behavior was evaluated. A characteristic curve was developed for the specific geometry and piezoelectric material.
339

Episodic Work-Family Conflict and Strain: A Dynamic Perspective

French, Kimberly A. 07 November 2017 (has links)
Given rising work and family demands in our society for both men and women, the experience of work-family conflict is commonplace. Work-family conflict occurs when the demands of work or family make it difficult to meet the demands of the alternate domain. A sizeable body of research has established work-family conflict and its nomological network. Despite decades of research, we have yet to form a precise understanding of when work-family conflicts occur and what happens when a conflict arises. The current research addresses these questions using an experience sampling, episodic approach. Two primary research questions are addressed. First, I used border and boundary theory to identify when work-family conflict episodes are likely to occur. Second, I used stressor-strain and allostatic load theories to examine what happens with regard to psychological, physiological, and behavioral strain following an episodic work-family conflict over time. The results suggest work-family conflict occurs when individuals transition in between work and family domains. Further, family-to-work conflict tends to occur in the morning, while work-to-family conflict tends to occur in the afternoon. Fatigue showed significant reactivity at the time of a family-to-work conflict and recovered in the following time point. Unhealthy eating also showed a sleeper pattern, such that unhealthy eating increased at the end of the day, following a work-to-family conflict. Unexpectedly, fatigue decreased at the time of a family-to-work conflict, indicating family-to-work conflict may be a restorative, rather than taxing. Post-hoc analyses showed some evidence that work-to-family conflict accumulation is associated with increased strain over the course of three days. Again, results suggest family-to-work conflict accumulation may reduce, rather than increase, strain. Implications for the theoretical relationship between work-family conflict and strain, as well as border/boundary theory are discussed. In addition, practical implications for flexible work initiatives and episodic research design are considered.
340

Remote Monitoring Systems For Substructural Health Monitoring

Collins, Jonathan D 26 June 2008 (has links)
Remote Wireless Monitoring Systems have made a large impact in the area of Structural Health Monitoring. However in the specialized sub-field of Substructural Health Monitoring, remote monitoring techniques have not made as much headway. First, monitoring systems are often retrofitted onto a structure. Therefore it is much harder to retrofit the substructure of a bridge or building. Second, many foundation elements such as driven piles or auger-cast piles are constructed in a way that makes installation difficult or can severely damage the sensing materials. This thesis presents two case studies of Remote Monitoring Systems for Substructural Health Monitoring applications that were carried out by the Geotechnical Research Department of The University of South Florida. The first is a thermal monitoring system for a Voided Shaft study. The second is a thermal, construction load, and ongoing health monitoring system of the St. Anthony Falls Bridge in Minnesota. Results show that the systems that were used provide adequate data collection, data storage, and data transmission. Furthermore, this data is easily analyzed and provided for public or private use on a dedicated website, which provides a fully automated and remote Substructural Health Monitoring System.

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