Thesis (Ph.D.)--University of Tulsa, 1987. / Page xv lacking. Bibliography: leaves 150-154.

Thesis (Ph. D.)--University of Texas at Austin, 2002. / Vita. Includes bibliographical references. Available also from UMI Company.

Thesis (Ph. D.)--University of Texas at Austin, 1998. / Vita. Includes bibliographical references (leaves 192-194). Available also in a digital version from Dissertation Abstracts.

Thesis (Ph. D.)--University of North Carolina at Greensboro, 2006. / Title from PDF title page screen. Advisor: Heather Helms ; submitted to the School of Human Environmental Sciences. Includes bibliographical references (p. 114-124).

Thesis (Ph. D.)--Drexel University, 2006. / Includes abstract and vita. Includes bibliographical references (leaves 78-88).

Thesis (M.A.) -- Central Connecticut State University, 2007. / Thesis advisor: James Conway "... in partial fulfillment of the requirements for the degree of Master of Arts in Health Psychology" Includes bibliographical references (leaves 56-67). Also available via the World Wide Web.

Analytical solutions to well hydraulic problems have restrictive assumptions that often do not match real world conditions. Although numerical models more closely match reality, they either ran too slowly to be practical or lacked accuracy because of coarse grid spacing and large time steps. Advances in computer power over the last few decades now allow for accurate, fast numerical models that handle complex flow systems. The purpose of this dissertation was to develop flexible and accurate numerical modeling codes for the simulation of hydrologic tests. One of these numerical modeling codes, the Slug Test Simulator (STS), was designed for the mechanics of a single well test, or slug test. STS can handle a variety of conditions including unconfined flow, partial penetration, layered heterogeneities, and the presence of a homogeneous well skin like existing codes. This program also extends on the capabilities of earlier codes with its ability to simulate a heterogeneous skin where K can vary in both the radial and vertical directions. STS has a clear user interface, can display graphical results, and allows the user to determine hydraulic conductivity through a trial-and-error curve-matching process. Comparisons of STS to the Cooper-Bredehoeft-Papadopulos analytical solution and the Kansas Geological Survey (KGS) semi-analytical solution produced near-identical curves under a wide variety of conditions. Numerous analytical studies have shown that the well skin is an important factor in the underestimation of hydraulic conductivity in slug tests. STS allows for the exploration of the well skin issue under conditions too complex for analytical models. Model trials revealed two key discoveries: 1) if any layers within the skin have the same hydraulic conductivity as the surrounding formation, flow is concentrated within these conduits and the resultant head response approaches the case when no skin is present; and 2) the two most important properties in determining the overall influence of the skin are specific storage and skin thickness. The first discovery suggests that extensive development activities can essentially eliminate any well skin impacts. Other factors such as partial penetration, the placement of the well screen, and anisotropy play insignificant roles in resultant head responses. Recent research is focusing on alternative direct- push (DP) methodologies to determine hydrologic properties. DP offers advantages over traditional well tests, but may yield inaccurate results if the screen becomes clogged during pushing activities. The Kansas Geological Survey (KGS) developed a new DP technique, the Direct-Push Permeameter (DPP), to overcome this limitation. Existing analytical or numerical models cannot address the specialized nature of DPP tests so a second numerical modeling code, the Direct Push Permeameter Simulator (DPSS), was developed. DPPS was generated by modifying STS so both numerical codes are similar in many ways, particularly with their flexibility and accuracy. The codes differ in how they handle vertical layering, the boundary conditions at the well, and the spreadsheet interfaces. DPPS was able to produce near-identical curves in comparison to the Theis analytical solution. DPPS was also able to reasonably recreate DPP field data conducted at two sites with distinctly different media properties. The GEMS and Nauen sites had an average error of 14.2% and 3.1%, respectively between the field data and DPPS simulations.

This thesis is concerned with a quantitative study of intermixing in GaAs/AlGaAs and ZnSe/ZnCdSe single quantum well semiconductor structures. In this study, a method of iterative isothermal anneals and photoluminescence used to characterize this phenomenon has enabled the evolution of the diffusion coefficients for the interdiffusion process with anneal time to be followed. The blue-shift emissions arising from this method are predicted by a model based on Fick's law of diffusion. This model is developed in an attempt to relate the energy shift that is observed experimentally to the diffusion length. The mixing is modelled using an error function expression to solve the diffusion equation so as to describe the variation in well shape which is attributed to compositional disordering induced during thermal processing. Using this approach, where evidence of intermixing was monitored, the emission would be expected to shift measurably. Data has been taken to cover a wide temperature range to establish values for the activation energy EA. From this data, it has been found that the diffusion coefficients at various temperatures are thermally activated with an energy of 3.6 +/- 0.2 eV in GaAs/AlGaAs. The data is compared with the available literature data taken under a wide range of experimental conditions. We show that despite the range of activation energies quoted in the literature all the data appears to be consistent with a single activation energy. Departures from the 'mean' value are ascribed to experimental uncertainties in determining the diffusion coefficients for example, to fluctuations in the composition of the material, to techniques used, or to a wide range of perturbations. Photoluminescence observations on ZnSe/ZnCdSe show that an improvement in the optical quality of these quantum well structures was found for anneals at temperatures (~500°C). A value of EA = 2.9 +/- 0.3 eV was derived from the experiments for the interdiffusion process over a 250 K temperature range and four decades of interdiffusion coefficient. The interdiffusion process of both these systems was inferred to be Fickian with no dependence on alloy composition or strain.

The thesis investigates the behaviour of aqueous montmorillonite suspensions and also the interactions between montmorillonite as a free standing film and in highly dispersed aqueous suspension with water soluble polymers used as additives in water based drilling fluids. FTIR microscopy and FTIR ATR spectroscopy have been employed to study in-situ dehydration of fully dispersed aqueous montmorillonite suspensions. The IR spectrum of the dispersed bentonite shows significant differences from that of a dry bentonite powder, which have been attributed to the hydration of the exchangeable cation. Drying, or concentrated salt solution causes the differences to disappear and this is attributed to the exchangeable cation settling back to its ditrigonal cavity in the silicate sheet of the mineral under these conditions. The adsorption of various molecular weights of neutral polyacrylamide (PAM) onto montmorillonite has been studied using FTIR transmission, ATR spectroscopy and XRD. Shifts seen in the NH[2] stretching and bending bands have been interpreted as being due to H-bonding with the outer co-ordination sphere of exchangeable cations. KCl has shown to have some influence on this system. Another neutral polymer used extensively in water based drilling fluids is polyalkylglycol (PAG). The adsorption of two molecular weights of this polymer from aqueous solutions of various concentrations have been monitored both in the presence and absence of KCl. The physical form of the montmorillonite (either as a free standing film or as a dispersed suspension), the concentration of the polymer solution, the polymer molecular weight and the presence of KCl all have significant effects on the adsorption of polymer. The stabilisation of montmorillonite films by PAG and PAG/KCl solutions has been monitored by ATR spectroscopy, and the dehydration of these films by polymer has been monitored using FTIR spectroscopy and XRD. The interaction of PAG is thought to be via hydrogen bonding with the innermost co-ordination sphere of the exchangeable cations which thus presents a hydrophobic surface to solvent molecules, preventing the film from collapse. Since all water based drilling fluids are multi-component systems, techniques previously used have been employed to study the competitive adsorption of the polyalkylglycol and polyacrylamide components. Preferential adsorption of the PAG is seen in these systems either due to the mass transport effects (PAG is considerably smaller than PAM) or due to PAG removing all but the inner cation hydration sphere, and presenting a hydrophobic surface for the PAM, and therefore preventing its adsorption.

Prosociality describes the tendency to engage in behaviours that aim to enhance or maintain the well-being of others, for example, sharing and co-operating. In children and adolescents this trait is often viewed as a core aspect of social competence and an important developmental outcome. Prosociality may also play an important role in how young people navigate their increasingly complex social world. This raises the question of whether individual differences in prosociality are related to young peoples’ well-being, such as their risk of developing psychological problems. The goal of the current series of research was to explore this question. A series of four studies was designed to answer this question. This research made use of pre-existing survey data, including the “mental health of children and young people in Great Britain, 2004” survey (Papers 3 & 4) and the “Understanding Society” survey (Paper 2), enabling access to large sample sizes. In Paper 1, a meta-analysis was undertaken to determine the nature of the relationship between prosociality and two important clinical outcomes, internalizing disorder and low self-esteem. This review identified a significant but small relationship between greater prosociality and reduced internalizing disorder or low self-esteem. In Paper 2, a longitudinal study explored the relationship between prosociality and well-being over a 1-year-period in children and adolescents. This study did not identify any prospective effect of prosociality upon subsequent changes in well-being. Two further studies explored the factors that may influence whether prosociality is linked to well-being. In Paper 3 the possibility that existing measures of prosociality may partly account for the small or null relationships observed so far (Papers 1 & 2) was explored by developing and validating a new measure of prosociality. This new measure appeared psychometrically robust and demonstrated advantages over pre-existing scales of prosociality. In Paper 4, a cross-sectional study was undertaken to explore whether the discrepancy in young peoples’ self-ratings and parental ratings of prosociality has a relationship with emotional problems (i.e., depression and anxiety). A moderator analysis found that self-rated and parent-rated prosociality may interact to determine risk of psychological problems in young people. This study suggested that the discrepancy in ratings of prosociality may be more important in predicting psychological problems than overall ratings by individual informants. Results support the relevance of prosociality to well-being in young people and highlight how factors such as the measurement of prosociality and the interpersonal context within which it occurs impact upon this relationship.