Texte remanié de: Dissertation--Siegen--Universität, 2002. / Bibliogr. p. 425-449.

Thèse de doctorat : Ethnologie : Paris 10 : 2008. / Thèse consultable uniquement dans l'enceinte de l'université Paris Ouest Nanterre La défense. Titre provenant de l'écran-titre.

Thesis (Ph. D.)--UCLA, 2009. / Vita. Description based on print version record. Includes bibliographical references (leaves 189-197).

Thesis (M.A.)--University of Central Florida, 2009. / Adviser: James Wright. Includes bibliographical references (p. 44-50).

Internal waves are generated in the ocean by oscillating tidal flow over bottom topography such as ridges, seamounts, and continental slopes. They are similar to the more familiar surface waves, but not being constrained to move on the surface, propagate throughout the bulk of the world oceans. Internal waves transmit energy over thousands of kilometers, ultimately breaking and releasing their energy into turbulence and mixing. Where these internal waves are generated, as well as where and how they break and cause mixing, has important effects on the general circulation of the ocean, which is in turn a major component in earth's climate. As a first step in a more thorough understanding of the evolution of internal waves in the ocean, it is important to characterize their generation. The two-dimensional generation problem has been studied for four decades, with ample experimental, numerical, and theoretical results. Most of this past work has also been done using linear, inviscid approximations. However, wave generation in the ocean is three-dimensional (3D), and in many locations, nonlinear and viscous effects can be significant. Recent advances in experimental and numerical techniques are only now making the fully nonlinear, 3D generation process accessible. We utilize these new techniques to perform both laboratory experiments and numerical simulations on internal wave generation in 3D. We find that a significant component of the internal wave field generated by tidal flow over 3D topography is radiated in the direction perpendicular to the tidal forcing direction. This could lead to substantial improvements of global internal wave generation models. In addition, we have developed a new method for statistical analysis of ocean data sets, and have found large regions in the deep ocean where internal waves may not propagate. This will also have important effects on the way researchers study the propagation of internal waves, which, when propagating downward, were previously thought to always reflect from the sea floor. / text

For decades, research has explored how family background shapes access to and success in postsecondary education. However, much less is known about the effect of family background on one’s educational and occupation success within specific fields. Given rapid advances in science and technology and a changing global economy, understanding these processes within science, technology, engineering, and mathematics (STEM) are particularly important to the broader understanding of stratification. Many recent studies in the U.S. stress the importance of increasing our STEM labor force to remain competitive in the global market, and demand for highly skilled workers is at an all-time high and increasing. While the demand for these jobs is high, many researchers argue that the supply of highly skilled workers is lagging behind. In order to meet these demands, many of these researchers point to increasing the talent pool by drawing from underrepresented groups. This study looks at how family socioeconomic background affects entry into STEM majors, persistence in STEM major, and early labor market outcomes among college graduates from STEM fields, and compares these patterns and processes to those in non-STEM fields. Results from this study show stronger SES differences in STEM fields than non-STEM fields at each point from college major choice to the labor market. Together, these results suggest that less socioeconomically advantaged students may be at a particular disadvantage in STEM fields. / text

Corpus Christi Bay in Texas is a wind driven system, and under most conditions winds over the bay mix the water column vertically. However, seasonal, episodic, bottom-water hypoxia has been observed in the bay in conjunction with vertical salinity stratification. This stratification may be caused by dense gravity currents entering the bay. Understanding and modeling the mechanisms that result in stratification in Corpus Christi Bay may help predict hypoxia, and for this reason that is the focus of this dissertation. An evaluation of existing gravity current modeling techniques shows that most currently available models are designed to capture either phenomena local to a gravity current, such as gravity current entrainment and spreading, or larger scale phenomena such as wind mixing and large-scale circulation, but not both. Because gravity current mixing in Corpus Christi Bay is enhanced by wind-induced turbulence, both local gravity current physics and wind mixing effects are critical elements governing gravity current propagation in Corpus Christi Bay. As existing models do not represent gravity current entrainment and wind mixing together, this dissertation develops a coupled model system that accounts explicitly for turbulent wind mixing of a bottom-boundary layer, in addition to representing other local features of dense gravity current propagation such as entrainment and spreading. The coupled model system consists of a 2D depth-averaged hydrodynamic model that calculates gravity current mixing and spreading, coupled with a 3D hydrodynamic model whose domain includes a lighter ambient fluid surrounding the gravity current. The coupled models have flexible boundary conditions that allow fluid exchange to represent mixing from both gravity current entrainment and wind mixing. The coupled model system’s development, verification and application in Corpus Christi Bay advances understanding of gravity current mechanisms, and contributes to our scientific understanding of hypoxia in Corpus Christi Bay. This modeling technique has the flexibility to be applied to other density-stratified systems that are shallow and potentially wind-driven, such as shallow desalination brine disposal sites. / text

A basic physical model of electrodecantation has been developed and tested. Experimental data of Belongia (1999) were used to compare with computational results obtained from the model. The model was developed to calculate the transient velocity field, electric potential and particle distribution for the parameter space encountered in stable colloidal dispersions. The model included the effects of a spatially nonuniform electric field that existed in the experiments of Belongia (1999) because of the type and position of the electrodes used. As a result, the model required numerical methods for its solution. The problem was found to depend largely on three dimensionless groups: Re, a Reynolds number, Pe an electric Péclet number and ¤ a large dimensionless parameter denoting the Grashof number divided by the Reynolds number. Because A^(1/3) >> 1, nonuniform computational meshes were needed to resolve the exceedingly thin natural convection boundary layers that occur. Additionally, because Pe >> 1, a flux-limiting (FCT) numerical method was used to solve the particle transport equation. Results from the basic physical model show excellent agreement with the scaling of the experimental data but exhibit about 80% relative error when compared with experimental data on the decantation time. Consequently, a physicochemical model of electrodecantation was developed to include electrical conductivity variations that develop as ions transport during electrodecantation. Results show markedly better agreement (about 10% relative error) with experimental data concerning the decantation rate. Additionally, the physicochemical model is able to predict the pH and electrical conductivity stratification that was measured experimentally by Belongia (1999). A problem concerning the electrohydrodynamic deformation of miscible fluids, with differing electromechanical properties (electrical conductivity and dielectric constant), was also investigated. Numerical results predicting the sense and extent of deformation for various values of the two fluids’ electrical conductivity ratio compare well (less than 10% relative error) with measurements by Rhodes, et al. (1989). The role of dielectric constant differences in electrohydrodynamic deformations was also investigated. It was determined that an O(1) difference in the fluids’ dielectric constants is necessary to produce electrohydrodynamic deformations on the time scales reported by Rhodes, et al. (1989) and Trau, et al. (1995).

This thesis includes four empirical studies investigating factors related to educational and occupational careers in a Swedish cohort born in 1953. Data from the longitudinal “Stockholm Birth Cohort study” (SBC) are used. In Studies I &amp; II I investigate educational careers among children whose parents were interviewed as part of the SBC study. In the last two studies I focus on children’s gender-atypical occupational preferences, as an outcome (Study III) and as a factor for adult occupational attainment among women (Study IV). Social capital, human capital and parent-child relation quality: interacting for children’s educational achievement? This study investigates the utility of social capital for children’s achievement, and if this utility interacts with human capital of the family and the quality of the parent-child relationship. Results show that social capital is directly related to children’s school grades and its utility for achievement does not depend on parents’ human capital. The utility of social capital is enhanced when combined with a very good parent-child relation. Family resources and mid-life level of education: a longitudinal study of the mediating influence of childhood parental involvement. This study focuses on the association between parents’ socio-economic resources and children’s mid-life level of attained education. Results show that this association is mediated by parental involvement in children’s schooling. However, the effect varies across types of parental involvement. Only parents’ educational aspirations for their children have direct mediating effects on the association between parents’ socio-economic resources and children’s mid-life level of attained education. Gender-atypical occupational preferences in childhood – findings from a Swedish cohort. This study investigates the association between parents’ socio-economic status and childhood gender-atypical occupational preferences. Results show that childhood occupational status preferences mediate the association between family socio-economic status and childhood gender-atypical occupational preferences, especially among girls. High-status employment among women – a longitudinal study of the role of childhood occupational preferences. This study investigates the association between childhood gender-atypical occupational preferences and occupational attainment in adulthood among girls in the SBC cohort. Results show that childhood gender-atypical occupational preferences are positively associated with attainment of high status occupations in adulthood / <p>At the time of the doctoral defense, the following papers were unpublished and had a status as follows: Paper 1: Epub ahead of print. Paper 2: Epub ahead of print. Paper 3: Manuscript. Paper 4: Manuscript.</p>

Equal opportunity offices have been described as agencies of organisational change, and the term ‘cultural change’ has been used to describe aspects of equal opportunity work.Universities are sites of organisational cultures where equal opportunity officers have worked in Australia for the past decade. In this time there have been significant changes to higher education, in terms of the size of the university sector in Australia, and also in terms of funding, governance and management. These changes in universities provided the context for questions about the roles of equal opportunity officers in universities, and how they may have changed. This research investigated the practice of equal opportunity officers in universities by using a grounded theory approach to generate understandings about how this group of university staff may have impacted on university cultures. The study develops links between theories of culture and organisational change that was situated in the practices of equal opportunity officers.The research identified a central conceptual category that was described as ‘picking the pitch’, as the main theme in the work of equal opportunity officers in identifying issues and gaining support for a cultural change agenda. All of the preliminary themes that were identified, and the interactions, the observations and the analysis of culture were prerequisites for ‘picking the pitch’.The thesis uses the research for further reflection and integration of the goals of equal opportunity, and the means that were available to equal opportunity officers to achieve these goals. The interactions of power and influence, and some of the limitations on equal opportunity officers are discussed.In the thesis the usefulness of the concept of culture to equal opportunity officers is examined, along with the underpinning theories about the mind of humanity that contributed to their approach to their task.Finally, the thesis discusses the impact of the research for equal opportunity officers, and for the universities in which they worked.