Universiẗat, Diss., 2004--Leipzig.

Universiẗat, Diss., 2005--Hohenheim.

Thesis (Ph. D.)--Ohio State University, 2007. / Title from first page of PDF file. Includes bibliographical references (p. 166-178).

No Abstract Provided

Members of the Legionellaceae cause respiratory infections in man; the most severe, pneumonic form is known as Legionnaires' disease. Of the 39 species described to date 16 have been associated with human disease, however the majority of reported cases of legionellosis are caused by Legionella pneumophila serogroup 1. A number of pathogenic bacteria regulate their virulence gene expression in response to environmental stimuli. Temperature and the availability of iron are considered to be stimuli which signal entry to a host environment. The first part of this study utilised chemostat culture to investigate the influence of growth temperature and the availability of iron on the physiology, morphology and virulence of L. pneumophila serogroup 1. This study demonstrated, for the first time, that the virulence of L. pneumophila was significantly reduced (P < 0.05) when the culture temperature was lowered from 37 to 24°C and this modulation was reversed by returning the temperature to 37°C which resulted in a statistically significant (P < 0.05) increase in virulence. Further experiments demonstrated that the concentration of iron in the growth medium also had an effect on virulence. Contrary to expectations iron-limited cultures were less virulent than those grown iron-replete. This modulation was also reversible with a return to virulence when iron-replete conditions were restored. The physiology and morphology of L. pneumophila were also influenced by both growth temperature and iron-limitation. At 24°C cultures consisted of flagellated short rods, whereas cultures grown at 37°C were pleomorphic and flagella were not evident. It was demonstrated that L. pneumophila accumulates the intracellular carbon storage compound, polyhydroxybutyrate, and that the proportion of the cell dry weight which it comprised varied with growth temperature, being maximal at 24°C. The ratio of saturated to unsaturated fatty acids in L. pneumophila decreased as the temperature was reduced to 24QC; this is a common strategy designed to maintain membrane fluidity. Siderophore production was detected in iron-limited cultures but not in iron replete cultures. Protease production was also affected by both growth temperature and iron-limitation. The BIOLOG bacterial identification system was modified for use with legionellae and this was used to investigate the metabolic versatility of these bacteria. A database containing substrate utilisation profiles of Legionella species was constructed using the modified system; this was then used to identify legionella isolates to species level. Evaporative cooling towers are a significant source of Legionnaires' disease accounting for the majority of outbreak cases in the United Kingdom. In the second part of this study a microbiologically-contained, fully-functional evaporative cooling tower was constructed and used to investigate factors that could influence the growth of L. pneumophila in such systems. The mode of operation of the cooling tower was found to influence the multiplication of legionellae in the system. Low-usage situations resulted in enhanced growth of L. pneumophila. Growth of L. pneumophila demonstrated a significant positive correlation with water temperature but its concentration decreased with increased conductivity. The concentrations of calcium, magnesium, potassium and zinc and the total hardness of the water all exhibited inverse relationships with legionella population size. The protocol for the emergency disinfection of cooling systems recommended in the Report of the Department of Health Expert Advisory Committee on Biocides did not eradicate L. pneumophila from the experimental cooling tower.

Endothermy refers to the ability of an individual to produce heat from internal sources, and allows animals to maintain a body temperature that is higher than their external environment. Although much is known about the benefits of endothermy, its origin is highly debated. Nonetheless, due to environmental variation, endotherms have to regulate their heat production (thermogenesis) in order to remain normothermic. An endotherms regulatory response seems to be body size dependent. Keeping warm during cold periods is energetically expensive, and for small mammals this is exacerbated by their high rate of heat loss due to high surface area to volume ratios. To compensate for the heat lost, small non-hibernating mammals must increase their level of thermogenesis. Much of our current understanding of thermogenic responses of small mammals is derived from laboratory acclimated animals, and studies on naturally acclimatized animals are uncommon. In addition, most studies on thermogenesis tend to focus on one level of animal organisation, such as subcellular, tissue or in-vivo, but seldom integrate these data. The aim of this study was to measure year-round variation in thermogenesis across all levels of organisation, using naturally acclimatized Rhabdomys pumilio individuals from the Nelson Mandela Metropolitan University, Port Elizabeth. It was predicted that the level of thermogenesis would be significantly higher during winter relative to other seasons in order to cope with the low ambient temperatures (Tas) experienced during this season. Open flow respirometry was used to measure the animal's oxygen consumption, as a proxy for metabolism; the by product of which is heat production. The animal's basal metabolic rate (BMR), nonshivering thermogenesis (NST) capacity and summit metabolic rate (MSUM) were measured. A Western blot analysis was used to determine the expression of uncoupling protein 1 (UCP 1) in the animals' brown adipose tissue (BAT), as well as determine its relative concentration. The cytochrome c oxidase (COX) activity of the animals' visceral organs and BAT was measured, as an indicator of the tissues' metabolic activity. COX activity was determined as the difference in the tissues' oxygen consumption before and after the addition of horse cytochrome c.

abstract: This study develops a theoretical model that explains how leaders come to adapt their leadership behaviors to achieve follower effectiveness. Mindfulness theory suggests that mindful individuals are better able to engage in self-regulation and I consider empathy, response flexibility, and emotional regulation as three self-regulatory processes in particular which likely impact the leader-follower relationship. I suggest that leaders who have the ability to self-regulate in these three ways will be better able to engage in leadership behavior characterized by adapting or flexing the specific types of leadership they demonstrate according to the needs of the situation and what their followers most require at a given time to perform at their best. When followers receive the type of situationally-appropriate support in the form of leader behavior, they are more effective (e.g. have higher job performance and extra-role performance). I validate a new trait and state measure of workplace mindfulness with multiple samples and utilize this new scale to collect data from leaders and followers from a government organization to test the theoretical relationships proposed in this study. I utilize an experience sampling methodology (ESM) design over 10 days to investigate the within-leader variation among variables in the study given theory suggesting the dynamic nature of the mindfulness, self-regulation, and situational leadership constructs which may not adequately be captured when data are collected at one point in time. Finally, I introduce organizational constraints as a moderator of the relationship between leader mindfulness and leader self- regulation in order to understand how stressors and strains outside the control of a leader may overload a leader’s ability to ultimately self-regulate his/her behavior. / Dissertation/Thesis / Doctoral Dissertation Business Administration 2015

abstract: This action research, mixed methods, case study examined middle school student perceptions of the effectiveness of Club Aspire. Club Aspire is an after-school program created to support the lowest achieving seventh and eighth graders in an Arizona K-8 school. The framework of this study comes from the theory of self-regulation, social learning theory and co-regulation. The primary focus of Club Aspire is to teach low achieving middle school students, self-regulation skills and learning strategies through goal setting, self-regulation learning strategy lessons and co-regulation activities. The study took place over 13 weeks and included 11 participants and answered the following research questions. How do middle school Elevate students perceive the impact of Club Aspire on their self-regulation and themselves as a learner? How does Club Aspire affect middle school Elevate students’ academic success? What do middle school Elevate students perceive as the most influential elements of Club Aspire? Data collection tools consisted of interviews, class work, referral data, pre- and post-questionnaire and benchmark assessment data. The study revealed that students made gains in self-regulation learning strategy usage, however, their academic achievement was not influenced. Students identified goal setting, learning self-regulation strategies and co-regulation activities with their peer partner as the most beneficial elements of Club Aspire. The study also revealed that student self-efficacy was increased throughout the semester. / Dissertation/Thesis / Doctoral Dissertation Leadership and Innovation 2017

No description available.

It has been well-established that Pseudomonas species possess extremely versatile metabolic systems allowing them to utilise a wide range of nutrient sources and, furthermore, that the regulation of these enzyme systems involves highly evolved and sophisticated regulatory machinery. This study examined the complexity of metabolic regulation in Pseudomonas using the hydantoin-hydrolysing system of the environmental isolate, Pseudomonas putida RU-KM3s. In this system, the genes encoding dihydropyrimidinase and β-ureidopropionase (dhp and bup) are arranged divergently on the chromosome, separated by a 616 bp intergenic region involved in the transcriptional regulation of these genes. The focus was on the transcriptional regulation of dhp expression. DHP activity was found to be sensitive to several environmental signals including growth phase, carbon catabolite repression (CCR), substrate induction and quorum sensing (QS). Bioinformatic analysis of the intergenic region upstream of dhp revealed a number of putative binding sites for transcriptional regulators, including recognition sequences for the alternate sigma factors σ54 and σ38, as well as for the global regulators Anr (for anaerobic regulator) and Vfr (for virulence factor regulator). The targeted disruption of the genes encoding the transcriptional regulators, Vfr and the major CCR protein, Crc, resulted in a partial relief from repression for the vfr- mutant under quorum sensing conditions and a general decrease in activity in the crc- mutant. This data suggested that both Vfr and Crc were involved in regulating DHP activity. Mutational analysis of the dhp promoter revealed that at least two sites were involved in regulating transcriptional activity, one which mediated activation and the other repression. These sites were designated as a putative Anr box, situated 232 bp from the start codon of dhp, and a CRP-like binding site, at a position 213 bp upstream of dhp. Taken together, this data shows the involvement of several global regulatory factors in controlling the expression of dhp. A complex synergistic model was proposed for the transcriptional regulation of dhp, involving alternate sigma factors in addition to both global and specific regulators and responding to a number of environmental signals associated with growth phase, including nutrient availability, cell density and oxygen status.