Thesis (M.S.)--Duquesne University, 2005. / Title from document title page. Abstract included in electronic submission form. Includes bibliographical references (p. 100-110) and index.

Negative Linear Compressibility (NLC), where a material expands in a given direction when subjected to hydrostatic compression, is a rare elastic property that has received much attention recently, but has yet to be used in practical applications. What are the mechanisms responsible for this property in crystals and man-made structures? Are all mechanisms somehow related to the wine-rack model? Can we find an even simpler and more fundamental elucidation of NLC? Following this mechanistic approach, can we then identify “engineering” materials with NLC? To answer these questions, I have used a combination of analytical modelling based on beam theory and finite element analysis, to investigate several structures. At first, I examine in great detail the standard wine-rack in 2D and equivalents in 3D and identify the aspect ratio (close to two) at which NLC is maximum. By adding spacers I demonstrate that a cross is not a necessary condition, and that simpler angle changes in chains are sufficient to generate NLC. Looking for materials with intersecting straight chains, “zig-zag” chains or quasi-helical structures, I find that carbon fibre mats, some extruded polymers and some woods exhibit NLC. Finally, I show that elliptical voids in 2D sheets can also generate NLC in a way related to the wine-rack. This thesis improves the understanding of the mechanism(s) responsible for NLC by proving that a wine-rack is not necessary. Perhaps more importantly it suggests that the property can be exploited in several relatively common materials.

Attentional bias is commonly associated with emotional disorders. However, potential transdiagnostic mediators of attentional bias, such as repetitive negative thinking (RNT) have been overlooked. The current study examined attentional biases associated with three forms of RNT and tested a proposed mediation model. Participants (N = 249) completed self-report measures, a repetitive thought induction, and an emotional face dot-probe measure of attentional bias. I hypothesized that RNT would be associated with attentional bias to angry, sad, and disgust faces, worry with angry faces, and rumination with sad faces after a negative thought induction. I also hypothesized that attentional bias scores would mediate the association between negative affect and RNT. Overall study hypotheses were not supported. Clinical worry was associated with slower reaction times to sad faces in the negative induction. RNT, worry, and rumination were not associated with attentional bias scores to emotional faces, and the mediation model was not supported.

Intrusive memories, coping strategies, negative appraisals, and perceptions of control were examined in an unselected undergraduate sample. Intrusive memory frequency was positively associated with emotion-avoidant coping, but unrelated to problem-focused and emotion-approach coping. Negative appraisals and perceptions of control partially mediated the relationship between intrusive memory frequency and emotion-avoidant coping. PTSD symptoms contributed additional variance to the partial mediation models. Overall, study findings demonstrated that the intrusive memory maintenance cycle found in PTSD and depression samples can exist in an unselected sample. Individual differences within this sample may relate to varying levels of executive control and trait mindfulness. Implications for clinical practice, limitations, and directions for future research are discussed.

The RAB guanosine triphosphates (RAS-related in brain) belong to the Ras superfamily of GTPases, and loss of RAB 25 expression has been reported in a number of breast cancer cases containing H-Ras point mutations, particularly triple negative breast cancers (TNBC), one of the most aggressive subtypes of breast cancer and associated with a poor prognosis. The mechanism involved in the progression of these tumors is poorly understood. In this study, we are trying to understand if loss of RAB25 expression in Human Mammary Epithelial Cell (HMEC) lines co-operates with H-Ras mutations and contributes to tumorigenesis. HMEC were immortalized by transduction with LXSN CDK4 R24C, a mutant form of cyclin-dependent kinase, followed by transduction with hTERT, catalytic subunit of the telomerase enzyme that permits the cells to exceed the Hayflick Limit and become immortal. We have found that with loss of RAB25 and over expression of mutant H-Ras61L, immortal HMEC undergo transformation. We have looked into the co-operativity between loss of Rab25 and H-Ras61L mutant by in-vitro studies to show their anchorage independent growth and increased ability to migrate. Furthermore, cells express low CD24, high CD44, and very low levels of Claudin indicating that cells acquire stem-like properties upon transformation. Loss of RAB25 and over-expression of H-ras61L resulted in increased expression of transcription markers Snail and Slug that drive these cells to lose E-cadherin and undergo Epithelial Mesenchymal Transition (EMT). This study shows that loss of RAB25 and over-expression of mutant H-Ras can transform HMEC and give rise to mesenchymal stem-like tumors. Our findings reveal that RAB25 functions as a tumor suppressor gene, and loss of RAB25 could serve as a novel biomarker in the prognosis of Claudin-low type of TNBC.

Doctor of Philosophy / Department of Human Ecology-Personal Financial Planning / Sonya L. Lutter / This study explored the influence of present-fatalism, present-hedonism, and future time perspectives on financial net worth. Time perspective has been shown to influence many behaviors, both non-financial and financial, but this is the first study that evaluated the relationship between time perspective and net worth. Net worth was divided into two variables, a dichotomous variable indicating those who had a negative net worth (defined as a net worth less than or equal to zero) and a continuous variable of the actual dollars of net worth of those who had a positive net worth (defined as a net worth greater than zero). Developing a separate negative net worth variable allowed this study to expand on prior research that focused solely on that aspect of net worth (Chen & Finke, 1996; Mountain & Hanna, 2012). Data was taken from the National Longitudinal Survey of Youth 1979 (NLSY79), using results primarily from the 2014 survey. A logistic regression was used to evaluate the negative net worth variable (Model 1) while an ordinary least squares (OLS) regression was used to analyze the influence on positive net worth (Model 2). This study found that present-fatalism increased the odds that an individual would have a negative net worth, while a future-orientation would decrease those odds. It found that present hedonism and future-orientation contributed to having a positive net worth. Model 1 had a Nagelkerke R Square of .367 and was able correctly to classify 77.2% of those who had a negative net worth (compared to 67.6% using only the intercept). In addition to time perspective findings, several control variables were incorporated into the study. Those who had a higher current income, who were male, who were married, and who owned a home had lower odds of having a negative net worth. Those who had a college education had lower odds of having a negative net worth compared to those with a high school diploma, while those who only attended grade school had greater odds of having a negative net worth compared to high school graduates. Blacks and Hispanics had greater odds of having a negative net worth compared to Whites. Risk tolerance, parent socio-economic status, and age were not significant predictors of negative net worth. Model 2 was significant, with an R² of .419. Risk tolerance, current income, parent socio-economic status, gender, age, marital status, and homeownership all contributed to a positive net worth. Compared to high school graduates, having a college education contributed to a positive net worth while having only a grade school education detracted from having a positive net worth. Being Black or Hispanic, as compared to being White, detracted from positive net worth. The results of this study must be juxtaposed against the limitations, which include the use of proxy variables for time perspective (which may not accurately reflect the constructs), erosion of the longitudinal sample over time, the use of a variable (risk tolerance) from a different year, non-normal distribution of some control variables, and potential endogeneity caused by the inclusion of homeownership as a control variable. Those limitations having been noted, this study found that the strong influence of future-orientation on reducing the odds of having a negative net worth and contributing to positive net worth is significant because it validates the entire concept of financial planning, which proposes that having a future financial path will help clients achieve financial success. It also opens up new possibilities in financial counseling, in that clients may benefit from time-perspective therapy and coaching. In addition, the findings of this study emphasize the positive influence of homeownership on net worth.

Thesis (MTech (Medical Technology))--Cape Technikon, 1998. / This study was undertaken to investigate resistance to aminoglycoside antibiotics and the transfer of resistance in selected Gram negative bacilli in hospitals in the Greater Durban area in order to determine whether the development of resistance in this region was similar to that found in other countries and whether it was the same in the hospitals in the region. It was intended that the study might expose the existence of nosocomial pathogens of a particular strain or endemic plasmids responsible for aminoglycoside antibiotic resistance. Strains of Klebsiella, Enterobacter and Serratia species and Escherichia coli resistant to gentamicin, tobramycin, netilmicin or amikacin were obtained. Resistance of the isolates obtained to the above aminoglycoside antibiotics was confirmed using a disc diffusion technique. Resistance mechanisms were initially assigned on the basis of resistance to these four aminoglycoside antibiotics. In approximately 50% of the isolates, including donor isolates and their respective transconjugants, resistance mechanisms were confirmed or revised on the basis of a changed resistance profile to a range of 12 aminoglycoside antibiotics in conjunction with DNA/DNA hybridization tests. Bacterial conjugation studies were performed on selected isolates to investigate the transfer of aminoglycoside resistance from Klebsiella pneumoniae isolates to recipient Escherichia coli. Plasmid profiles of all isolates and Escherichia colitransconjugants were compared to establish similarities. Isolates in three of the four genera of bacteria and all isolates collectively, demonstrated the greatest incidence of resistance to tobramycin. Amikacin resistance was, in all groups of isolates, the least frequently encountered. Collectively, the most frequent mechanisms of resistance were the AAC(3)-V and AAC(6')-1 enzymes One large hospital showed a high frequency of the AAC(3)-V modifying enzyme while in other hospitals a wider range of enzyme resistance mechanisms were evident. Plasmid profiles were generally dissimilar within and between different genera and the different hospitals. / Mangosuthu Technikon Research Fund

The last half of the twentieth century into the twenty-first century, in the West, has been referred to as postmodern. Postmodernity represents a stage in a society after having passed through a nihilism, itself produced by the universal commodification inherent in late stage capitalism. Here we explore the progress of devaluation through Adorno’s negative dialects to ascertain the potential for truth and authenticity in the object. Informing Adorno’s negative dialectics, were Kant, Hegel, and Marx. Through their dialectics, Adorno postulated the effect of commodities, as objects, within the first part of the 20th century, and how the lack of potential for truth and freedom in these objects anticipated the nihilism of both the late capitalism period, into the postmodern period. This nihilism itself, was anticipated by Nietzsche. Further, this entire focus on and influence of commodities on the individual, from the early twentieth century to the present is referred to as the commodity structure and itself can be equated to Heidegger’s falling prey. Once the subject has had the valuation or meaning of their lives stripped via this universal commodification of the commodity structure, this paper will argue through the works of Heidegger and Nietzsche and the role of the aesthetic, only then can the subject in the postmodern period reclaim qua participation in one’s own becoming towards both truth and authenticity, as well as freedom.

A thinker of impurity, Rancière is most often read as proposing an alternative to the ontology of the political. Against the many attempts to restore a pure sense of politics and of its public space, Rancière maintains the place of politics in a common appearance that is identical to reality. Though typically seen as having broken with the Marxist tradition, I argue here that it is possible to find in his fragmentary style something like a negative dialectic. While politics is what his works address, it is also how it is addressed. Politics, and its assertion of an apparently impossible equality, must be lived out by critique and not merely described. In doing just this, Rancière offers a renewed take on the western-Marxist tradition’s politics of aesthetics. Indeed, I maintain that Rancière, far from breaking with Marxism full stop, instead effects a reversal, a reversal of education into politics.

Caulobacters are gram-negative bacteria that have a biphasic life cycle consisting of a swarmer and a stalked stage. As a result they have elicited interest as a simple developmental model. Less attention has focussed on their role in the environment, although they have been found in almost every aquatic environment as well as in many soils. Caulobacters are often described as oligotrophic bacteria because of their prevalence in pristine waters but have now been isolated from the relatively nutrient-rich wastewater environment. In order to learn more about this population some basic characterization was carried out and an assay system to determine their prevalence in sewage plants was designed. Most of the organisms isolated from sewage treatment facilities had similar gross morphological features, but differed in holdfast composition, total protein profile, antibiotic resistance and restriction fragment length polymorphism, thereby indicating a greater diversity than originally assumed. Most of the organisms hybridized with flagellin and surface array genes that had previously been cloned, and only one of 155 non-Caulobacter sewage isolates hybridized with the flagellin gene probe; consequently these were used in a DNA-based enumeration strategy. DNA was isolated directly from sewage and probed with the flagellin and the surface array gene probes. The signals obtained were compared to standards made up of pooled Caulobacter DNA from the sewage isolates and non-Caulobacter DNA from organisms also present in sewage. Using this assay Caulobacters could only be detected above the 1% level, which was higher than their proportion in the wastewater environment. It appears that this approach will not be useful in monitoring Caulobacters in treatment plants unless a more highly conserved or higher copy number probe is found. / Science, Faculty of / Microbiology and Immunology, Department of / Graduate