A local isotropic damage coupled hyperelastic-plastic framework is formulated in principal axes where thermo-mechanical extensions are also addressed. It is shown that, in a functional setting, treatment of many damage growth models, including ones originated from phenomenological models (with formal thermodynamical derivations), micro-mechanical models or fracture criteria, proposed in the literature, is possible. Quasi-unilateral damage evolutionary forms are given with special emphasis on the feasibility of formulations in principal axes. Local integration procedures are summarized starting from a full set of seven equations which are simplified step by step initially to two and finally to one where different operator split methodologies such as elastic predictor-plastic/damage corrector (simultaneous plastic-damage solution scheme) and elastic predictor-plastic corrector-damage deteriorator (staggered plasticdamage solution scheme) are given. For regularization of the post peak response with softening due to damage and temperature, Perzyna type viscosity is devised. Analytical forms accompanied with algorithmic expressions including the consistent material tangents are derived and the models are implemented as UMAT and UMATHT subroutines for ABAQUS/Standard, VUMAT subroutines for ABAQUS/Explicit and UFINITE subroutines for MSC.Marc. The subroutines are used in certain application problems including numerical modeling of discrete internal cracks, namely chevron cracks, in direct forward extrusion process where comparison with the experimental facts show the predicting capability of the model, isoerror map production for accuracy assessment of the local integration methods, and development two novel necking triggering methods in the context of a damage coupled environment.

Thesis (Ph. D.)--University of Washington, 2003. / Vita. Includes bibliographical references (leaves 128-159).

published_or_final_version / Civil Engineering / Master / Master of Philosophy

Previously our laboratory had identified a novel component of the Staphylococcus aureus regulatory network, an extracytoplasmic function ó factor, óS, involved in stress response and disease causation. Here we present additional characterization of óS, demonstrating a role for it in protection against DNA damage, cell wall disruption and interaction with components of the innate immune system. Promoter mapping reveals the existence of four unique sigS start sites, one of which appears to be subject to auto-regulation. Transcriptional profiling revealed that sigS expression remains low in a number of S. aureus wild-types, but is upregulated in the highly mutated strain RN4220. Further analysis demonstrates sigS expression is inducible upon exposure to a variety of chemical stressors that elicit DNA damage, including methyl methanesulfonate (MMS) and ciprofloxacin, as well as those that disrupt cell wall stability, such as ampicillin and oxacillin. Ex vivo transcriptional analysis reveals that significant expression of sigS can be induced upon phagocytosis by RAW 264.7 murine macrophage-like cells. Regulation of óS appears to be unique, as the downstream encoded protein, SACOL1828, seemingly acts as a positive activator, rather than as an expected anti-sigma factor. Using a global transposon screen we have elucidated additional genes implicated in the regulation of sigS, including those involved in cell wall stability, cellular detoxification, virulence and DNA base excision repair. Phenotypically, óS mutants display sensitivity to a broad range of DNA damaging agents, such as ultraviolet light, MMS and ethidium bromide. These effects are seemingly mediated via regulation of the purine biosynthesis pathway, as microarray, proteomic and qRT-PCR analysis of óS mutants reveal decreased transcription of all genes involved. Enzymatic profiling of PurA involved in adenine biosynthesis, demonstrates decreased activity in the óS mutant. Finally, we provide further evidence for the role of óS in S. aureus pathogenesis, revealing that sigS mutants display decreased ability to cause localized infections and are impaired in their interactions with components of the human innate immune system. Collectively, our data argues for the important, and perhaps novel, role of óS in the stress and virulence responses of S. aureus.

Hibridiniai baltymai, koduojami sulietų lamB ir lacZ genų susiriša su išvirkščiomis E.coli ląstelių plazminės membranos pūslelėmis. Sąveika su plazmine membrane priklauso nuo geno secA produkto buvimo. Hibridinių baltymų susirišimas su membrana priklauso nuo išorinės membranos baltymo LamB polipeptidinės grandinės ilgio. Aktyviosios deguonies formos, susidariusios fotosensibilizuojant eukariotų ląsteles lipofiliniu sensibilizatoriumi sukelia membranų pažaidas, padidina lipidų peoksidacijos lygį ir laktato dehidrogenazės išėjimą iš ląstelių. Vidinių ląstelių pažaidos sumažina ląstelių oksidoreduktazių aktyvumą ir ATP kiekį. Aktyviųjų deguonies formų susidarymas mitochondrijų vidinėje ertmėje buvo indukuotas rodaminu arba safraninu. Oksidacinio streso, sukelto mitochondrijų viduje, poveikis skyrėsi nuo įvairių ląstelės membranų fotopažaidų. Ląstelės atsakas į oksidacinį stresą mitochondrijų viduje priklausė nuo poveikio dozės. Pažaidos iki CD50 nesukėlė žymaus ląstelės gyvybingumo sumažėjimo. Didesnės fotopažaidos virš CD70 indukavo apoptozę, aktyvino kaspazę-3 ir iniciavo citochromo išėjimą iš mitochondrijų. / Hybrid proteins encoded by the fused lamB and lacZ genes were able to reconstitute to the membrane of the inside-out vesicles. The reconstitution of the cytoplasmic membrane vesicles was shown to be dependent on the gene sec A product. The interaction of the hybrid proteins with the membranes depended on the length of the LamB polypeptide chain. Production of ROS after photosensibilization with the lipophylic photosensitizer induced the damage to the cell membranes, enhanced lipid peroxidation and resulted in the leakage of lactate dehydrogenase from the cells. The damage of the inner cell membranes induced the decrease of the activity of cell oxidoreductases and the amount of ATP. For the stimulated production of ROS in the inner space of mitochondria, rhodamine123- and safranin-mediated photodynamic treatment was employed. Cell response to the oxidative insult in the mitochondrial interior was different from the response to the photodamage produced in other cellular membranes. Cell response to the oxidative stress in the mitochondrial interior was dose dependent. Damage up to CD50 did not reveal hallmarks of dead cells. Severe damage (beyond CD70) induced apoptosis following release of cytochrome c and caspase activation.

In this thesis I will present an approach and apparatus for detecting and precisely characterizing any dose-dependent changes in the functional behaviour of a data converter in a neutron radiation environment. Depending on the data converter such changes could include shifts in the gain, offset, noise, or linearity of the device output. The approach leverages the neutron flux produced by an Americium-Beryllium radioisotope neutron source, and is meant to emulate the neutron environment near a Cm-244 source, as found in the sensor head of the APXS instrument. This method uses a relatively low dose rate (configurable by proximity to the source) which allows for long-term monitoring and characterization of parametric changes in device behaviour. It has the additional benefit of not requiring a reactor or accelerator, and can therefore run unattended when necessary. The prototype system, which is designed to allow the data converter to be operating during irradiation, uses LVDS signalling to drive and extract data from a minimal test board which is placed in proximity to the neutron source, and a Virtex-4 FPGA board to provide clock and power, and to perform signal processing. By separating the majority of the test equipment from the neutron environment, any radiation effects will be isolated to the DUT and a minimal set of supporting devices. The prototype design is presented here, along with initial characterization results and first test results on a commercial, off-the-shelf data converter. / Canadian Space Agency, Ontario Centres of Excellence, MacDonald, Dettwiler, and Associates

Computers are used for diagnostic and training in the neuropsychological rehabilitation. PLANTEST is a program for the IBM-PC that was developed for diagnostic support. It implements a test that gives information about the reduced ability of brain-injured patients to make plans regarding a certain task.The presented thesis describes a knowledge-based system that can be used to develop new test versions for PLANTEST. The program is called SolvePT and it can prove the solubility of test material used in PLANTEST. It can also automatically generate new test material. The program uses an exhaustive forward-chaining, depth-first search and is implemented in Prolog. The datastructures and algorithm of the program as well as space and time requirements are discussed. / Department of Computer Science

A detailed seismic performance assessment procedure has been developed for reinforced concrete frame buildings with masonry in-fill walls and reinforced concrete frames including shear walls. The procedure uses member damage functions, in terms of inter-story drift ratios, developed for the primary components: columns, beams, in-fill walls and shear walls. Analytical investigations carried out to determine the influence of a number of parameters on the damageability of components were combined with existing experimental data to develop component damage functions. A new approach has been developed to combine component damage states to determine the story and building level performance states. The procedure has been calibrated and compared with other procedures by predicting the observed performance of seven buildings exposed to recent earthquakes in Turkey. It was observed that the damage experienced by most of the components of these buildings was predicted satisfactorily, and that the observed building damage states were captured. The procedure can be used for a reliable performance assessment as well as performance-based design of the RC frame structures.

Thesis (Ph. D.)--University of Missouri--Columbia, 2004. / Typescript. Vita. Includes bibliographical references (leaves 156-180). Also issued on the Internet.

Thesis (Ph. D.)--Universität Hamburg, 1996. / Includes bibliographical references (p. 163-172).