Abnormal regulation of mitochondrial deoxyribonucleoside triphosphate pools can lead to mitochondrial DNA depletion syndromes, a set of genetic diseases associated with depletion of mitochondrial DNA. Besides mitochondrial DNA depletion syndromes, improper maintenance of mitochondrial deoxyribonucleoside triphosphate pools and mitochondrial DNA have also been implicated in a host of other human pathologies. The unifying objective of this dissertation was to enhance our knowledge of the regulation of mitochondrial deoxyribonucleoside triphosphate pools. The first step was to investigate the characteristics of mitochondrial and cytoplasmic deoxyribonucleoside triphosphate levels. I calculated mitochondrial and cytoplasmic deoxyribonucleoside triphosphate concentrations from previously published data. Cytoplasmic and mitochondrial deoxyribonucleoside triphosphates are strongly correlated in normal cells but not in transformed cells. Following up this discovery with analysis of gene expression, I discovered that, consistent with the trends in deoxyribonucleoside triphosphate concentrations in cells, genes coding for enzymes that maintain cytoplasmic and mitochondrial deoxyribonucleoside triphosphates have correlated expression across normal tissues but not across transformed tissues. To further understand the influence of cytoplasmic deoxyribonucleoside triphosphates on mitochondrial deoxyribonucleoside triphosphates, I simulated the metabolism of mitochondrial deoxyribonucleosides with a computational model. Cytoplasmic deoxyribonucleotides have a substantial and indispensable contribution to mitochondrial deoxyribonucleoside triphosphates in most circumstances. My results further show that import from the cytoplasm would need to occur at either deoxyribonucleoside diphosphate or triphosphate levels.

Worker responses towards absenteeism

Previous studies have shown that L-tryptophan treatment has been known to reduce blood pressure (BP) in hypertensive rats. L-tryptophan is converted to serotonin (5-HT), a potent vasoconstrictor agonist. The direct vascular effects of L-tryptophan, an essential amino acid, and the mechanism that contributes to the fall in BP have not been fully explored. The present study aims to examine the direct vascular responses to both D- and L- tryptophan using perfused mesenteric vascular bed, an ex-vivo preparation that represents the resistance function of circulation. Perfusion was maintained at a constant flow rate (5 mL/min) with Krebs buffer (pH 7.4, 37˚C) after isolation from 12 to 14 week old male Sprague-Dawley rats. The basal perfusion pressure (PP) (mean ± SEM) was 27 ± 3 mmHg. Inclusion of D- and L-isomers in the perfusion medium led to concentration-dependent increase in PP. While the maximal response (Emax) was similar, D-tryptophan (EC50: 0.25 ± 0.12* µmol; Emax: 128 ± 8 mmHg) was more potent (lower EC50 value; *p < 0.01) than L-tryptophan (EC50: 0.79 ± 0.30 µmol; Emax: 141 ± 7 mmHg). Inclusion of increasing concentrations (2, 5 and 10 nM) of the 5-HT2A selective antagonist, ketanserin, led to parallel right-ward shifts in the concentration-response curves to D- and L-tryptophan with restoration of their Emax. In contrast, the α1 selective agonist, methoxamine (30 µM), constricted preparations, both D- (IC50: 0.94 ± 0.30* µmol; Imax: 96 ± 2%) and L-tryptophan (IC50: 2.8 ± 1.0 µmol Imax: 88± 1%) evoked concentration-dependent vasodilatation, an effect that was resistant to blockade by either ketanserin or other 5-HT antagonists. Again, D-tryptophan was more potent than L-tryptophan in the presence of 5-HT antagonist (*p < 0.05). Neither the removal of endothelium nor incubation with selective inhibitors of dilatory mediators released from the endothelium, failed to alter the vasodilator responses to D- and L-tryptophan. In potassium chloride depolarized preparations, L-tryptophan evoked an additive vasoconstrictor response. The vasodilator responses to L-tryptophan persisted in the presence of glibenclamide, a KATP channel inhibitor, or tetraethyl ammonium, a BKCa channel inhibitor, or BaCl2, a Kir channel inhibitor, or ouabain, a Na+-K+-ATPase pump inhibitor. These data confirm that the essential amino acid, L-tryptophan, as well as its D-isomer, evoke a biphasic vasoconstrictor and vasodilator responses in the resistance type mesenteric vascular bed. While the vasoconstrictor responses are mediated by activation of vascular 5-HT receptors, the endothelium-independent vasodilator responses are not linked to activation of vascular 5-HT receptors, vascular potassium channels, Na+-K+-ATPase pump or via inhibition of voltage-operated Ca2+-channels. Plasma concentration of L-tryptophan is about 90 - 120 µM. The endothelium/5-HT independent direct vasodilator responses characterized here for the first time could account for the antihypertensive/ BP lowering effect of L-tryptophan reported earlier by other laboratories.

El proceso de planificación del transporte consta de varias fases, una de ellas es la etapa de asignación, la cual sirve para crear nuevos escenarios para la toma de decisiones. Los problemas de asignación de tráfico se resuelven optimizando los flujos en una determinada red de transporte, los algoritmos resuelven problemas de asignación de un origen contra varios destinos. Las funciones que describen el flujo de transporte, son funciones no lineales con restricciones lineales, estas funciones son efectivas cuando consideran solo algunos parámetros principales involucrados en los problemas de flujos de redes, tales como el costo de desplazamiento y el tiempo de desplazamiento. En la presente Tesis se implementa el algoritmo de Frank-Wolfe para optimizar el proceso de asignación a una red de transporte. / The transportation planning process consists of several phases, one of them is the assignments stage, which is used to create new scenarios for decision making. The assignments problems of traffic are resolved optimizing network flows in a certain network transport, the algorithms solve problems from a origin to multiple destinations. The functions that describe the flow of transport, are nonlinear functions with linear constraints, these functions are effective when they consider only some main parameters involved in the problems of flows in networks, such as the replacement cost and displacement time. In the present thesis is implemented the Frank-Wolfe algorithm to optimize the process of assignment to a transport network.

The Electron Energy Corporation (EEC) along with the National Aeronautics and Space Administration (NASA) is researching magnetic bearings. The purpose of this research was to design and develop a high-temperature (1000�F) magnetic bearing system using High Temperature Permanent Magnets (HTPM), developed by the EEC. The entire system consisted of two radial bearings, one thrust bearing, one motor and 2 sets of catcher bearings. This high temperature magnetic bearing system will be used in high performance, high speed and high temperature applications like space vehicles, jet engines and deep sea equipment. The bearing system had a target design to carry a load equal to 500 lb-f (2225N). Another objective was to design and build a test rig fixture to measure the load capacity of the designed high temperature radial magnetic bearing (HTRMB) called Radial Bearing Force Test Rig (RBFTR). A novel feature of this high temperature magnetic bearing is its homopolar construction which incorporates state of the art high temperature, 1000 �F, permanent magnets. A second feature is its fault tolerance capability which provides the desired control forces even if half the coils have failed. The permanent magnet bias of the radial magnetic bearing reduces the amount of current required for magnetic bearing operation. This reduces the power loss due to the coil current resistance and also increases the system efficiency because magnetic field of the HTPM is used to take up the major portion of the static load on the bearing. The bias flux of the homopolar radial bearing is produced by the EEC HTPM to reduce the related ohmic losses of an electromagnetic circuit significantly. An experimental procedure was developed using the Radial Bearing Force Test Rig (RBTFR) to measure actual load capacity of the designed bearing at the test rig. All the results obtained from the experiment were compiled and analyzed to determine the relation between bearing force, applied current and temperature.

Thesis (M.S.C.S.)--University of South Florida, 2004. / Title from PDF of title page. Document formatted into pages; contains 63 pages. Includes bibliographical references.

Thesis (Ph. D.)--University of California, San Diego, 2003. / Vita. Includes bibliographical references (leaves 83-90).

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Depression is a significant mental health concern with a pivotal increase of incidence during adolescence, specifically for females. Currently, cognitive behavioral therapy (CBT) is the most widely tested treatment for depression. Yet, it is unclear how CBT functions to produce effective outcomes. Adult studies have shown that behavioral components of CBT are more effective than cognitive components in reducing depression at acute treatment. Both behavioral and cognitive components have been shown to be effective in preventing relapse of depressive symptoms at follow up. Yet less is understood about how treatment components work together to provide positive outcomes, particularly for depressed youth. The overall goal of this study was to examine which parts of treatment (cognitive and/or behavioral) aid in symptom reduction and to determine if treatment outcome is mediated by cognitive change. Forty two pre-adolescent girls, aged 9-14, participated in a 20-session manualized group CBT program. The first portion of treatment (session 1-9) focused the behavioral intervention and the second portion of treatment (sessions 11-19) focused on cognitive interventions while continuing to reinforce behavioral interventions when necessary. Self report measures and diagnostic interviews were completed at pre-treatment and post-treatment. Using multiple regression analyses, the findings of this study supported the role of behavioral and cognitive interventions in reducing depression. Behavioral interventions were found to significantly reduce depression at post-treatment. Additionally, cognitive interventions were found to play a small, but significant role in post-treatment outcome, with preliminary evidence that cognitive interventions could also be linked to treatment outcome one year later. Treatment specificity could not be tested, as the cognitive change of depressed girls was not directly influenced by the behavior and cognitive interventions. Exploratory analysis demonstrated the significant role of behavioral techniques such as behavior activation, positive reinforcement, homework review, and skills training in predicting outcome of treatment. Implications of the results, limitations, and recommendations for future research are provided. / text

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