Thesis (Ph. D.)--University of Washington, 2003. / Vita. Includes bibliographical references (p. 153-163).

Congestive Heart Failure (CHF) is a major fatal disease today in the United States. The heart's function is a mechanical one. To diagnose and treat CHF effectively there is a need to understand at the microstructural level, the differences in the response of the myocardium to a change in its mechanical environment. Hence to assess growth and remodeling processes in the myocardium, the fiber and myolaminar structure of two groups of Dahl salt-sensitive rats were compared: low salt (LS) normal controls and a high salt (HS) group with hearts in "transitional eutrophy" defined by normal size and shape but in transition from pressure overload hypertrophy to dilated hypertrophy. To create the HS group with transitional eutrophy, we fed Dahl salt-sensitive rats, a sustained high salt diet from age 6 wks till sacrifice at age 11-13 wks. Such rats have a heart that transitions from too thick (pressure overload hypertrophy at about age 9 wks) to too thin (dilated hypertrophy at about age 15 wks to death) with a transitional period (age 11-13 wks) having normal size and shape. Fiber angles, sheet angles, number and thickness of sheets were measured in the septum at four transmural quarters (TQ1 to TQ4 with TQ1 being closest to LV and TQ4 closest to RV). A uniformity index was defined to characterize sheet angle dispersion. Upon comparison to LS controls, the HS group had normal size hearts with normal shape. However, there was a significant increase in the number of sheets, which corresponded with a significant decrease in the thickness of sheets in all quarters in HS group. Differences in fiber angles were significant in TQ1, TQ2, and TQ4 with fiber angles more positive in HS group. Differences in sheet angles and uniformity index were not significant. Despite having a normal size and shape, we found that hearts in a state of transitional eutrophy have a significantly different fiber and sheet morphology. The experimental data was used to develop a model that represents the path to failure that may be taken by the myolaminae when the heart is subjected to excessive pressure overload.

Thesis (Ph. D.)--University of Washington, 1998. / Vita. Includes bibliographical references (p. [182]-192).

Thesis (MS)--University of Montana, 2009. / Contents viewed on December 19, 2009. Title from author supplied metadata. Includes bibliographical references.

Thesis (Ph. D.)--University of Washington, 1995. / Vita. Includes bibliographical references (leaves [177]-182).

Thesis (Ph. D.)--University of Washington, 2005. / Vita. Includes bibliographical references (p. 98-104).

In this thesis, I present results from a two-year study of strain-rate variations along a flow line on the western margin of the Greenland ice sheet. I used baseline network solutions to investigate variations in longitudinal strain rates over the 2006 and 2007 melt seasons. Analyses revealed high-magnitude, short-duration events of increased longitudinal strain early in the melt season coincident with a high melt year, suggesting a link between melt production and its effects on seasonal ice flow. Results from 2006 data show that longitudinal strain rates became variable shortly after the onset of melt (day 186) changing up to ~ 15 x 10-4 a-1 within 24 hours. The onset of melting occurred earlier in 2007 (day 153) and was also followed closely by strain-rate deviation from background rates calculated prior to melting. The data revealed rapid (hours to days), high-magnitude (two to ten times greater than background rates) changes in longitudinal strain rates (hereafter referred to as ‘high-strain’ events) that occurred both on the small-scale (affecting 1-4 baselines) and on the large-scale (affecting 5 or more baselines). Large-scale high-strain events were infrequent, on the order of two events per season. Events were likely caused by drainage of supraglacial meltwater that penetrated to the bed of the glacier raising the basal water pressure. The increase in pressure reduced the basal resistive stress, and allowed rapid local acceleration. The basal stress reduction was transmitted to areas of higher stress which resulted in longitudinal compression of the ice down glacier and longitudinal extension up glacier. The evolution of high-strain events altered longitudinal strain rates more than 15 km along flow from the site of initiation. I estimated the origin and spatial extent of highstrain events by assessing the magnitude of the strain-rate variations in various baselines, and observing whether the altered strain regime was extensive or compressive. Magnitude and timing of changes in strain suggest that high-strain events originated in the ablation zone, the equilibrium zone, and inland of the equilibrium zone, and indicate that short-term altered stress conditions are not confined to the ablation zone. The background strain-rate for 2007 (~ -7 x 10-4 a-1 for a 37 km longitudinal baseline) was similar to the 2006 longitudinal background rate. When extrapolating the 2006 background rate over the melt season, the expected change in baseline length (~ 11 m) was similar to the observed change (~ 9 m). In contrast, when extrapolating the 2007 background rate over the melt season, the expected shortening was ~ 6 m, but the observed shortening was less than 1 m. This result suggests that seasonal high-strain events have the ability to alter longitudinal baseline length, allowing a greater ice flux to lower elevations where melting occurs for a larger portion of the year. However, the cumulative seasonal effects of both large-scale and small-scale strain events are modest, and indicate that seasonal changes in strain rates have a minor effect on the overall stability of the ice sheet. Nevertheless, it is possible that over much longer timescales these seasonal changes may become more important with increasing temperatures and available melt. Results from this study may also be useful in making broader inferences regarding the response of grounded portions of the ice sheet to seasonal changes in basal resistive stress.

This study presents the experimental results that characterize a nastic sheet material’s performance. We defined nastic sheet as a McKibben muscle designed from a foundation that would be embedded as an array in an elastomer matrix. The goal is to be able to utilize the embedded McKibben sheets in the biomedical industry as an improvement to the synthetic devices and/or processes. One mechanism that might produce these improvements is to mimic the biological materials that form functional organs, biological structures, and active tissues. Linking human technology and natural structures is and will continue to be important to society for several reasons. It would improve: (1) the lifestyle of humans in regards to artificial parts that mimic human parts (which will allow us to live longer), (2) artificial limb functionality, and (3) comfort and aesthetics. The objective is focused on characterizing and evaluating McKibben muscles as an embedded muscle sheet by building McKibben muscles and testing them alone and in sheets with one, two, three, and five muscles. The sheets would be known as a single, double, triple and quintuple embedded sheet. Another objective is to determine the performance penalty that embedding puts on the material. The experiments performed used several different approaches, such as analytical models, tensile test analysis, and prototype construction of the specimens. All specimens were designed to have a constant final length of 120mm, being embedded in a polyurethane matrix. We characterized the fundamental performance of a McKibben muscle and each specific embedded sheet. We measured the specimens’ work-density and quantified the inactive matrix’s impact on work-density. Based on the results, several improvements were suggested on the fabrication of the specimens. The experiment shows positive potential outcome that could be utilized in the biomedical field, but the results would improve with the suggestions provided in the study. A sample of the results - the actual work-density for both the single and doubleembedded sheets showed an increase to 7.82% and 2.96% consecutively. Once the specimens are removed from the mold, the McKibben muscle automatically tries to retract to its initial state while the polyurethane matrix tries to stay at its initial state.

Spreadsheets for critical applications, such as financial reporting, are widely created and used by many people with no expertise in programming or software development. It is well known, however, that creating spreadsheets is an error-prone process. Several methodologies have been designed to reduce these errors. In this thesis we characterise the patterns and functional relationships among the formula cells and the corresponding data cells that commonly occur in spreadsheets, and show how the patterns occurring in a given sheet can be generalised to produce a template structure representing the family of spreadsheets of which the given sheet is a member. Finally, we show how this generalisation can be translated into an L-sheets program from which instances of this family can be generated.

Thesis (Ph. D.)--University of Missouri-Columbia, 2006. / The entire dissertation/thesis text is included in the research.pdf file; the official abstract appears in the short.pdf file (which also appears in the research.pdf); a non-technical general description, or public abstract, appears in the public.pdf file. Title from title screen of research.pdf file (viewed on April 29, 2009) Vita. Includes bibliographical references.