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Environmental temperature exhibits profound effects on the activity and ecology of ectotherms through its impact on muscle contractile physiology. While the performance of locomotor behaviors powered by muscle contraction directly decreases by at least 33% over a 10°C drop in body temperature, chameleons are known to feed, presumably with high performance, at body temperatures where sympatric lizard species remain inactive. I propose that ballistic movements that are powered by the recoil of preloaded elastic and collagenous tissues are less thermally dependent than movements that rely on direct muscular power. Despite the reduced thermal sensitivity of the elastic-recoil powered movement, I propose that the muscles associated with preloading these elastic tissues are themselves thermally sensitive and at low temperature, will take longer to load the elastic tissues. Finally, I expect that because of the different effect of temperature on elastic-recoil-powered and muscle-powered movements, performance declines for elastic-recoil-powered tongue projection at low temperature will not vary between species along an environmental temperature gradient (i.e., thermal effects will be the same for all species). Conversely, performance declines for muscle powered tongue retraction at low temperature will be lower in species from colder environments along an environmental temperature gradient. To test these predictions, I used high-speed videography, electromyography and in vitro muscle contractile experiment techniques in conjunction with temperature manipulations to test the mechanistic principles in Chamaeleo calyptratus. I then used high-speed videography at different temperatures in three Bradypodion species from different habitats in South Africa to compare thermal effects on elastic-recoil and muscle-powered movements in different species. I found that the elastic-recoil mechanism of tongue projection in chameleons circumvents the constraints that low temperature imposes on muscle rate properties, thereby reducing the thermal dependence of tongue projection. In all species examined, tongue projection was relatively thermally robust, maintaining a high degree of maximal performance at temperatures as low as 15°C. In contrast, the associated muscle-powered tongue retraction was strongly effected by temperature and experienced substantial performance declines over the same temperature range. While tongue projection performance was itself thermally robust, muscle contractile dynamics of the tongue projector muscle, which preloads the elastic elements responsible for powering projection, was strongly affected by temperature. Similarly, at cooler temperatures the tongue projector muscle became active earlier relative to the onset of tongue projection, due to the reduced rate of tension buildup and the resulting increase in time required to load the elastic elements of the tongue with the required force to subsequently power tongue projection. Further, the effect of temperature on both tongue projection performance and tongue retraction performance was found to vary between species living in different thermal environments. This suggests that despite differences in how temperature affects the performance of these different movement types, both elastic-recoil-powered movements and muscle-powered movements may experience selective pressure to optimize their performance to their environments. Based on these findings, I suggest that the relative thermal independence of tongue projection in chameleons is a more general characteristic of elastic-recoil-powered mechanisms and organisms that use elastic recoil mechanisms for ecologically important movements, such as feeding and locomotion, may benefit from an expanded thermal niche. Further, given the prevalence of elastic power-amplification mechanisms in ectotherms, the benefit of reduced thermal sensitivity may promote the evolution of these mechanisms in other ectothermic animals. Finally, I propose that temperature manipulations may be a useful methodological approach to testing for the presence or prevalence of elastic recoil in powering other biomechanical systems. While these studies examined thermal effects on ballistic tongue projection and tongue retraction in chameleons at difference mechanistic levels and within the framework of how these thermal relationships may be affected by their local environment, many of the results apply more broadly to similar systems in other ectotherms. Comparison of these findings to similar elastically powered systems may help solidify the generality of these findings among other taxa.

Electrochromic films undergo a colour change when small ions and electrons are inserted into them, under the influence of an applied electric field. These films are also known as ion-intercalation electrodes, and may be incorporated into glazing structures more commonly known as 'smart windows'. Smart windows are that which may be used to control the amount of heat and light entering a building and may therefore be used to minimise the energy consumption associated with heating, cooling and lighting. The commercial success of smart windows, requires that they operate reproducibly at temperatures up to approximately 70ºC, for many tens of thousands of colouring and bleaching cycles. An understanding of the underlying kinetic processes over a wide temperature range is therefore needed, in order to determine suitable control strategies and switching conditions capable of fulfilling these requirements. The research detailed in this thesis has involved an investigation into the kinetic behaviour of ion-intercalation electrodes, and simulation of the electrical response as a means of developing a tool for predicting and then optimising electrochromic switching. More specifically, the electrical and optical properties of electrochromic thin films of WO3/TiO2 have been studied over a wide temperature range, appropriate for the operation of electrochromic windows. The magnitude of the voltages required for coloration and bleaching significantly reduces as temperature increases. Some irreversibility was observed at high temperature, as well as a reduction in coloration efficiency. Further investigation revealed that self-bleaching and irreversibility effects were caused by the presence of water, and this problem was exacerbated at high temperature. Post-experiment chemical analysis of a film sample revealed that some trapping of the inserted ions had occurred, however the amount of ions remaining in the film was much smaller than expected. The results suggested that a large quantity of the lithium ions injected into the film were lost to the electrolyte after many cycles, possibly accompanied by some film dissolution. Experimental work carried out in a dry-box showed that films may be cycled reversibly in a very dry environment, and the optical properties were independent of temperature under these conditions. Unfortunately, the conditions which led to reversible cycling and good electrochromic memory, also resulted in very long response times for film bleaching. This result implies that a good electrochromic memory and a fast response are mutually competitive aims. Data from high temperature experiments was simulated with a mathematical model and the mobility of lithium ions inside the electrochromic films was estimated in the process. The estimated diffusion coefficients agreed well with published values, and exhibited an Arrhenius dependence on temperature. Activation energies for diffusion were calculated and the results were very reasonable. Some deviation from ideal Arrhenius behaviour was observed for the estimated diffusion coefficients at high temperature. It is likely that the rate limiting mechanism changes from diffusive motion of ions at low temperature, to charge transfer at high temperature.

Master of Science / Civil Engineering / Stacey Tucker / Recent climate changes may affect the stability of our infrastructure in many ways. This study investigated the effects of fine-grained soil temperature on erosion rate. If climate change is shown to affect the erodibility of soils the impacts must be identified to monitor the stability of existing infrastructure, improve design of levees and structures founded in erosive environments, and to prevent sediment loss and stream meanders. Fine-grained soil erosion is complicated by the dynamic linkage of multiple parameters, including physical, biological and geochemical properties. This study held constant all parameters that influence fine-grained soil erodibility while only varying soil temperature in order to study the effects it has on erodibility. This study also confirmed previous findings that water temperature affects soil erodibility. The main objective of this study was to investigate the effects of fine-grained soil temperature on erosion rate. This study also instrumented a turbidity sensor to reliably map soil erosion. Based on this research, the conclusion was made that an increase in soil temperature increases soil erosion rate. The turbidity sensor was a valuable tool for comparing soil erosion. Future studies should investigate the effects soil temperatures below room temperature, the magnitude of temperature increase or decrease, and the effects of cyclic heating and cooling on fine grained soil erodibility.

Temperature effects on the development of the zebrafish embryos and larvae and adults were examined. It was found that the earlier in development a temperature change was performed on an embryo, the more significant the change in survival and/or subsequent development. Thus, viable temperature ranges for zebrafish widened significantly as development proceeded. Adults reared and bred at 25oC produced embryos that were significantly more successful at the lower range of rearing temperatures compared to embryos produced from adults reared at 28oC. The majority of this study focused on the physiological effects of swim training during development in the zebrafish. The earlier in development the zebrafish larvae were trained, the greater the mortality. Trained free swimming larvae had a significantly higher routine oxygen consumption after 11 days of training, and a higher mass specific routine metabolic rate after 8 and 11 days of training. Trained free swimming larvae consumed significantly less oxygen during swimming and were more efficient at locomotion, compared to control larvae. Training enhanced survival during exposure to extreme hypoxia in all age groups. Performance aspects of training were investigated in attempt to quantify training effects and in most cases, trained fish performed significantly better than controls. As blood vessels formed during development, they decreased in cross sectional area from days two to six. It was also shown that the variability in visual stroke volume measurements could be reduced significantly by using a third dimension in the analysis with a more accurate volume equation. Finally, the ontogeny of cardiac control was evaluated. The adrenergic receptors were the first to respond to pharmacological stimulation but were closely followed by cholinergic pharmacological stimulation a few days later. There was a significant cholinergic tone present in day 15 zebrafish larvae which persisted. Although an adrenergic tone was not documented in this study, this does not prove its lack of existence.

Drumming was recorded for 11 of 13 Nearctic stonefly species, representing 4 families. Both male and female signals were obtained from 5 species, and were either 2-way or 3-way communications. Signals were species-specific; those of males and females varied from 3-39 and 1-14 beats/ signal, respectively. Duration of male signals varied from 105-8,016 ms; those of females, except Perlinella drymo (1 beat), varied from 402-1318 ms. Signals among related taxa showed greatest similarities. Duration of male signals of Perlinella drymo became progressively shorter at each of 4 temperatures from 7-29 0C. Females of Perlinella drymo would only repeatedly answer male signals recorded at near their own temperature, and would not repeatedly answer recorded male signals of 8 other species.

The performance of settling tanks depends on several interrelated processes and factors that include: hydrodynamics, settling, turbulence, sludge rheology, flocculation, temperature changes and heat exchange, geometry, loading, the nature of the floc, the atmospheric conditions and the total dissolved solids concentration. A Quasi-3D (Q3D) clarifier model has been developed to include the following factors: axisymmetric hydrodynamics (including the swirl component), five types of settling (nonsettleable particles, unflocculated discrete settling, flocculated discrete settling, hindered settling and compression), turbulence, sludge rheology, flocculation with four classes of particles, temperature changes and surface heat exchange with the atmosphere, various external and internal geometry configurations, unsteady solids and hydraulic loading, the nature of the floc settling/interaction. The model includes: shear flocculation, differential settling flocculation and sweep flocculation. The Q3D model reproduces the major features of the hydrodynamic processes and solids distribution on secondary clarifiers. When the model is executed with the field derived settling characteristics, it can accurately predict the effluent and recirculation suspended solids concentrations. The model has been formulated to conserve fluid, tracer and solids mass. The model has been developed and tested using field data from the UNO Pilot Plant and the Jefferson Parish Waste Water Treatment Plant located at Marrero, Louisiana. A field testing procedure is presented that addressees all of the settling regimes that are encountered in a Secondary Settling Tank. Results obtained with the Q3D model indicate that the flocculation process plays a major role in the effluent suspended solids (ESS) on secondary clarifiers. The extent of actual flocculation depends on the design of the center well and on the concentration of the incoming mixed liquor suspended solids (MLSS). The center well promotes flocculation, but its most important benefit is the improvement on the tank hydrodynamics. The changes in temperature on secondary clarifiers play an important role on the performance of secondary settling tanks. The gravity induced radial velocities in the sludge blanket are higher than the radial velocities of the scraper in the region near the hopper, therefore the blades are not highly effective in conveying the solids in this region.

<p>This thesis aims to measure the rate of radon loss from water in a systematic way. The dependence on surface area, temperature and concentration will be investigated. The experiments were done at UWC by creating radon using radium sources and then measuring the radon concentrations inside a vacuum chamber to obtain the speed of radon escape from the water. The results are compared to a model [Cal 2002] where the radon concentration in the air and hence the transfer rate is measured using a RAD7 radon detector. Since the equations cannot be solved analytically, a numerical solution is employed. The radon transfer velocity coefficient is found to be (1.9&plusmn / 0.5)&times / 10-6m/s. This value indicates that the escape of radon should not be a problem when a sample is open to the air for a minute or two.</p>

No description available.

The variation in properties of Polypropylene (PP) / Ethylene Vinyl Acetate (EVA) blends upon EVA content, temperature, and light stability were followed by using tensile testing, impact testing, and differential scanning calorimetry (DSC). Young&rsquo / s modulus of the blends decreased with increasing drawing temperature and EVA content. The stress at break values of the blends slightly increased with EVA whereas decreased with drawing temperature. The percent strain at break values of the blends were found to increase abruptly by increasing EVA content and drawing temperature. These changes in the mechanical properties are the indication of compatibility. The impact tests were performed only at 0&deg / C, 25&deg / C and the impact strength increased with the temperature and EVA content, but none of the samples were broken at higher testing temperatures. The effect of stabilizer was very obvious because stabilizer-free samples failed after 400 hours whereas, the samples with stabilizer resisted up to 750 hours. Elongation values of the samples decreased because of increasing brittleness by UV irradiation. We also observed chain stiffening effect by crosslinking in all samples upon UV irradiation. Thermal analysis of the blends of the drawn samples showed an increasing trend of crsytallinity with increasing drawing temperature. Increasing drawing temperature made polymer chains more flexible because of the increasing chain mobility. These flexible chains were then oriented in one direction during tensile testing and therefore uniaxial crystallization occurred. The morphology of impact and tensile tests samples were also analyzed by scanning electron microscope (SEM). The fibrillation of pure PP is higher than the fibrillation of the blends.