One of the principal challenges of primary blast injury research is imitation of shock waves accurately and consistently in a safe and tunable platform. Existing simulators have been effective in these goals but have not been conducive for in vitro models due to their large size and air-mediated wave propagation. In this thesis, a redesigned benchtop shock wave generator (SWG) has provided a platform for in vitro models. A pulsed power generator charges a capacitor and discharges the capacitor through a bridge wire. The discharge causes the bridge wire to experience phase changes, momentarily becoming a gas or plasma. In this moment, the bridge wire expands radially and creates a pressure wave in the surrounding water. As the wave propagates, it forms a shock wave and strikes the cell platform at the far end of the conical tank. Current design efforts are focused on the tunability of the SWG, by varying the bridge wire material and diameter. Five materials at three bridge wire diameters have been tested. Each bridge wire was inserted into the SWG via a pinching mechanism. Either side of the pinching mechanism was connected to either terminal of the capacitor. When the pulsed power generator was cycled, the bridge wire was vaporized and generated a shock wave. A piezoelectric sensor near the wide end of the tank recorded the passing of the shock wave, which was used to derive various pressure metrics that correlate to injury. The sample size for each combination of diameter and material was five, with a grand total of seventy-five samples run. Two-way ANOVAs measuring the impacts of bridge wire material and diameter on a variety of shock wave metrics found that the diameter played a significant role in determining the peak overpressure and positive impulse generated while the main effect of material played a much smaller role. The interaction between material and diameter was also found to be significant. The tunable benchtop SWG provides a platform for exploration of primary blast injury using in vitro models. By adjusting the bridge wire diameter, the SWG can generate waves with a variety of shock wave metrics, providing an opportunity for researchers to address various degrees of injury. With the addition of this technology to the efforts to understand primary blast injury, development of treatments and protective equipment can be expedited. / Master of Science / Primary blast injury, the injury caused by the blast wave moving through the body, has been affecting those exposed to blast for nearly a century, since the regular use of conventional explosives in World War I. As equipment and war has changed in the past two decades, there has been heightened interest in understanding the effects of blast waves on the body. To assist in this research, blast wave simulators have been developed to recreate the blast wave in a controlled environment. However, current designs are not conducive to experiments on cultured cells. A new blast wave simulator, called the shock wave generator (SWG), has been designed as a platform for cultured cell-based experiments. The simulator generates a shock wave by exploding a thin bridge wire using high electrical current. The explosion occurs underwater, generating a shock wave capable of injuring cells at the opposite end of the tank. A platform such as this provides multiple opportunities to tune the pressure metrics related to the shock waves. Bridge wire material and volume play critical roles in the resulting shock wave, working together to define the amount of energy required to vaporize the bridge wire. Five materials and three diameters, a derivative of the wire volume, were investigated to determine their impacts on the resulting peak pressure, positive duration, and positive impulse. While wire material was not found to have a significant impact on peak pressure, wire diameter had a significant effect on the resulting overpressures. The thickest wire generated the lowest peak pressure while the thinner wires generated higher peak pressures. The thinner wires were not significantly different from one another. A similar result was found for positive duration and impulse. Overall, the use of an exploding wire to generate shock waves is applicable as an injury mechanism for cell cultures in primary blast injury research. This work along with future work will provide a tunable and controlled platform that has opened a new frontier for investigating the primary blast injury.

Small heat shock proteins (hsp) have been implicated in mediation of classic preconditioning in the rabbit. Hsp27 is a terminal substrate of the p38 MAPK cascade. One and 2D gel electrophoresis and immunoblotting of cell fractions was used to determine p38 MAPK and hsp27 phosphorylation levels, respectively, during in vitro ischemia in control, calyculin A (Cal A)-treated (protein phosphatase inhibitor), SB203580-treated (p38MAPK inhibitor) and preconditioned (IPC) isolated adult rabbit cardiomyocytes. The dual phosphorylation of p38 MAPK was increased by early ischemia (30-60 min), after which there was a loss of total cytosolic p38 MAPK. The ischemic increase of p38 MAPK dual phosphorylation was enhanced by IPC. Cal A strongly activated dual phosphorylation of p38 MAPK in oxygenated cells and this was maintained into early ischemia. SB203580 inhibited the dual phosphorylation of p38 MAPK and attenuated the loss of total cytosolic p38 MAPK. In each protocol, ischemia translocated hsp27 from the cytosolic fraction to the cytoskeletal fraction at similar rates and extents. Hsp27 phosphorylation was quantitated as the fraction of diphosphorylated hsp27, based on IEF mobility shifts of hsp27 phosphorylation isoforms. In oxygenated control cells, cytosolic and cytoskeletal hsp27 was highly phosphorylated. After 90 min ischemia, cytoskeletal hsp27 was markedly dephosphorylaled. Cal A slightly increased control cytoskeletal hsp27 phosphorylation. During ischemic incubation, Cal A blocked ischemic dephosphorylation. SB203580 accelerated ischemic hsp27 dephosphorylation and injury. IPC insignificantly decreased the initial rate of ischemic dephosphorylation of hsp27, but not the extent of dephosphorylation in later ischemia. Phosphorylation is regulated by both kinase and phosphatase activities. IPC protection was not correlated with a significant increase in cytosolic or cytoskeletal hsp27 phosphorylation levels during prolonged (> 60-90 min) ischemia.

The study of soldier’s experience is important to understanding the effect that wars have on society. In the latter part of the 19th century the experience of warfare changed due to advances in weapons technology. The defensive tactic of trench warfare gained new importance. The most prolific use of trench warfare occured on the Western Front in the First World War, but it was during the siege of Petersburg in the American Civil War that extensive trenches were first used with technologically advanced weapons. By comparing the siege of Petersburg with the Western Front, it is clear that similar conditions elicited similar emotional reactions from soldiers. The most common reactions were fraternization and war neurosis. Fraternization was more prevelant during the siege of Petersburg than at other times during the war. Fraternization was also common on the Western Front. The reasons for this vary, but are all linked to the nature of trench warfare. War neurosis was also caused by the conditions of the trenches. It was a bigger problem at Petersburg and on the Western Front than it was for soldiers in other conflicts. Trench warfare created these emotional reactions. / Master of Arts

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No description available.

Interpolation is essential in digital image processing, especially magnification. Many different approaches to interpolation specific to magnification have been developed in an effort to overcome the shortcomings of bilinear and bicubic interpolation. One of these approaches, Constraint-Based Interpolation, produces an image that is free of jaggies and has less blurring than bilinear or bicubic interpolation. Although Constraint-Based Interpolation produces a visually pleasing image, there are user-chosen parameters that make the algorithm difficult to use. In this thesis we propose a method for automatic selection of those parameters and an extension of Constraint-Based Interpolation to other forms of image manipulation, such as skew, rotation, warp, or any other invertable image transformation. By extending Constaint-Based Interpolation the same improvements observed in magnification could be observed in these other image transformations.

In this thesis, we review the stability problem for traveling waves and discuss the Evans function, an emerging tool in the stability analysis of traveling waves. We describe some recent developments in the numerical computation of the Evans function and discuss STABLAB, an interactive MATLAB based tool box that we developed. In addition, we verify the Evans function for shock layers in Burgers equation and the p-system with and without capillarity, as well as pulses in the generalized Kortweg-de Vries (gKdV) equation. We conduct a new study of parallel shock layers in isentropic magnetohydrodynamics (MHD) obtaining results consistent with stability.

Military aircraft generate high-amplitude noise which can cause injury to attending personnel. Efforts to mitigate the effects of this noise require a detailed understanding of the propagation of the noise, which was shown previously to be nonlinear. This thesis presents an analysis of high-amplitude noise propagation, emphasizing measures used to quantify the importance of considering nonlinearity. Two measures of the importance of nonlinearity are compared. These measures are the wave steepening factor and a skewness estimate. The wave steepening factor is a measure of how much nonlinear waveform steepening has occurred in a waveform. The skewness estimate is the skewness of the first time-derivatives of the pressure amplitudes, and can be considered a measure of the shock content in a waveform. These two measures are analyzed analytically in terms of the Earnshaw, Fubini, Fay, and Khokhlov solutions to the Burgers equation. In addition, an analysis of how discrete sampling affects the estimation of these quantities is also presented. It is determined that the wave steepening factor is robust with respect to low sampling rates, but the skewness of the first time-derivatives of the pressure amplitudes is not robust, and requires very large sampling rates to be adequately estimated. Using numerical and experimental techniques, the two nonlinearity measures are applied to more complicated waveforms, such as Gaussian noise and noise with jet noise-like statistics. It is found that the evolution of the two nonlinearity measures discussed above for noise signals is distinctive in various ways. In particular, the skewness of the first time derivative of the pressure amplitudes suggest that noise waveforms experience nonlinear phenomena faster than initially sinusoidal signals, while the wave steepening factor suggests that they occur at approximately the same rate. The measures are then applied to full-scale military aircraft. By comparing these nonlinearity metrics with the results of the analytical, numerical, and experimental results found in this thesis, it is determined that nonlinearity is likely to be significant in the near field of a military aircraft at military and afterburner engine conditions.

AB-type protein toxins such as cholera toxin (CT) consist of a catalytic A subunit and a cell-binding B subunit. CT proceeds through the secretory pathway in reverse, termed retrograde trafficking, and is delivered to the endoplasmic reticulum (ER). In order for the catalytic A1 subunit to become active it must separate from the rest of the holotoxin, and this dissociation event occurs in the ER lumen. CTA1 assumes an unfolded conformation upon dissociation from the holotoxin and is recognized by ERassociated degradation (ERAD), a quality control system that recognizes and exports misfolded proteins to the cytosol for degradation by the 26S proteasome. CTA1 is not degraded by the 26S proteasome because it has few sites for poly-ubitiquination, which is recognized by the cap of the 26S proteasome for degradation. Thus, CTA1 escapes the degradation of ERAD while at the same time using it as a transport mechanism into the cytosol. It was originally proposed that CTA1 is thermally stable and that ER chaperones actively unfolded CTA1 for translocation to the cytosol. In contrast, we hypothesized that the dissociated CTA1 subunit would unfold spontaneously at 37°C. This study focused on the three conditions linked to CTA1 instability and translocation: (i) CTA1 dissociation from the holotoxin, (ii) the translocation-competent conformation of CTA1, and the extraction of CTA1 from the ER into the cytosol. Disruption of any of these events will confer resistance to the toxin. The original model suggested that PDI actively unfolds CTA1 to allow for translocation. However, Fourier transform infrared iv spectroscopy (FTIR) and surface plasmon resonance (SPR) data we have gathered demonstrated that PDI dislodges CTA1 from the rest of the holotoxin without unfolding CTA1. Once released by the holotoxin, CTA1 spontaneously unfolds. PDI is thus required for the toxicity of CT, but not as an unfoldase as originally proposed. CTA1 must maintain an unfolded conformation to keep its translocation-competent state. Based on our model, if CTA1 is stabilized then it will not be able to activate the ERAD translocation system. Our SPR and toxicity results demonstrated that treatment with 4- phenylbutyrate (PBA), a chemical chaperone, stabilizes the structure of CTA1. This stabilization resulted in a decrease in translocation from the ER to the cytosol and a block of intoxication, which makes it a viable candidate for a therapeutic. Because CTA1 exits the ER in an unfolded state, there must be a driving force for this translocation. We hypothesized that Hsp90, a cytosolic chaperone, is responsible for the translocation of CTA1 across the membrane. Previous research had shown Hsp90 to be present on the cytosolic face of the ER and had also shown that Hsp90 will refold exogenously added proteins that enter the cytosol. Using drug treatments and RNAi, we found that Hsp90 is required for the translocation of CTA1 from the ER lumen to the cytosol, a brand new function for this chaperone. We have provided evidence to support a new, substantially different model of CTA1 translocation. CTA1 does not masquerade as a misfolded protein in order to utilize ERAD for entry into the cytosol; it actually becomes misfolded and is treated as any other ERAD substrate. The spontaneous unfolding of CTA1 is the key to its v recognition by ERAD and ultimately its translocation into the cytosol. Host factors play very important roles in intoxication by AB toxins and are targets for blocking intoxication.

The combustion behavior of methane and ethane is important to the study of natural gas and other alternative fuels that are comprised primarily of these two basic hydrocarbons. Understanding the transition from methane-dominated ignition kinetics to ethane-dominated kinetics for increasing levels of ethane is also of fundamental interest toward the understanding of hydrocarbon chemical kinetics. Much research has been conducted on the two fuels individually, but experimental data of the combustion of blends of methane and ethane is limited to ratios that recreate typical natural gas compositions (up to ~20% ethane molar concentration). The goal of this study was to provide a comprehensive data set of ignition delay times of the combustion of blends of methane and ethane at near atmospheric pressure. A group of ten diluted CH4/C2H6/O2/Ar mixtures of varying concentrations, fuel blend ratios, and equivalence ratios (0.5 and 1.0) were studied over the temperature range 1223 to 2248 K and over the pressure range 0.65 to 1.42 atm using a new shock tube at the University of Central Florida Gas Dynamics Laboratory. Mixtures were diluted with either 75 or 98% argon by volume. The fuel blend ratio was varied between 100% CH4 and 100% C2H6. Reaction progress was monitored by observing chemiluminescence emission from CH* at 431 nm and the pressure. Experimental data were compared against three detailed chemical kinetics mechanisms. Model predictions of CH* emission profiles and derived ignition delay times were plotted against the experimental data. The models agree well with the experimental data for mixtures with low levels of ethane, up to 25% molar concentration, but show increasing error as the relative ethane fuel concentration increases. The predictions of the separate models also diverge from each other with increasing relative ethane fuel concentration. Therefore, the data set obtained from the present work provides valuable information for the future improvement of chemical kinetics models for ethane combustion.