The Earth’s upper atmosphere is suffused by radiation caused primarily by a bombardment of Cosmic Rays, as a result of which it is hazardous for human beings as well as sensitive electronic equipment on board flight vehicles. A series of ground based as well as airborne experiments were performed using Polylactic Acid (PLA), Acrylonitrile-Butadiene-Styrene (ABS) and High Impact Polystyrene (HIPS), in order to investigate the applicability of polymers that can meet today’s needs for lightweight, multifunctional, and cost efficiency in radiation shielding of electronic equipment. It was found that PLA at 8 mm thickness has an effectiveness of 66% against gamma radiation (i.e., it blocked 66% of the gamma radiation). Therefore, it was decided to proceed with a high altitude balloon experiment with an 8 mm thickness of PLA. The shield was demonstrated to be reasonably effective in attenuating radiation from cosmic rays.

Micro aerial vehicle development and atmospheric flight on Mars are areas that require research in very low Reynolds number flight. Facilities for studying these problems are not widely available. The upper atmosphere of the Earth, approximately 100,000 feet AGL, is readily available and closely resembles the atmosphere on Mars, in both temperature and density. This low density also allows normal size test geometry with a very low Reynolds number. This solves a problem in micro aerial vehicle development; it can be very difficult to manufacture instrumented test apparatus in the small sizes required for conventional testing. This thesis documents the design, construction, and testing of a glider designed to be released from a weather balloon at 100,000 feet AGL and operate in this environment, collecting airfoil and aircraft performance data. The challenges of designing a vehicle to operate in a low Reynolds number, low temperature environment are addressed.

High altitude balloons are an effective, inexpensive and readily available conduit for conducting near space and low Reynolds number experimentation. Experiments are being developed that will use high altitude balloons as carriers for near space and low Reynolds test vehicles. The first step in developing this capability is to create a system that is able to log collected data and track and control a high altitude balloon payload. It is also beneficial that this system be flexible enough to accept different sensor types, communication methods and connection and release linkages. By combining the flexibility of microcontroller biased circuitry and the availability of commercial off the shelf products an economical design solution to this problem has been be achieved. Analysis of this system has been performed and the design has been fabricated, tested and specially modified to withstand the extreme conditions of high altitude flight.

High altitude photography represents a new, potentially valuable, but largely untested information source for the interpretation of surficial deposits. It differs significantly in sensitivity and perspective from conventional aerial photography. It posesses different values and limitations which must be evaluated in their own right. The photography examined is shown to provide an excellent and reliable record of stream pattern geometry, and of stream flow regularity characteristics which are related to deposit slope form and material characteristics. The important image density component of the photographic record must be corrected for distortion but shows a consistent relationship with characteristics of near surface deposit hydrology. Photography and imagery from high or orbital altitudes will soon be a widely if not universally available information source. It is evident that such information can make a valid and useful contribution in geomorphic studies. This information is complimentary to existing techniques of data collection, and likely to realize substantial savings in time and efficiency while permitting wider application of findings. / Thesis / Master of Science (MSc)

<p> Agricultural land use in the Niagara Peninsula was examined using high altitude colour infrared aerial photography obtained from aircraft. A visual analysis of the photography revealed that it contained great detail, and that the hue and density of the images were especially important in the interpretation process. In the subsequent densitometric investigation, it was found that quantified image density alone was of limited value in land use recognition, due to the density distortion inherent in the photography. The numerical data were much more useful when the ratios of densities in two emulsion layers of the film were determined, since this procedure largely removed the distortion element. </p> / Thesis / Bachelor of Arts (BA)

High altitude is characterized by chronically low ambient temperatures and oxygen. To survive, highland native deer mice (Peromyscus maniculatus) are capable of high rates of prolonged thermogenesis due to elevated aerobic capacity (V̇O2max) in hypoxia. Deer mice primarily use fats to fuel their high metabolic rates for heat production. Carnitine palmitoyl-transferase 1 (CPT-1) is a rate-limiting step in mitochondrial fat oxidation, and a reduction in CPT-I sensitivity for its substrate L-carnitine is associated with a reduction in muscle fat use during high intensity exercise in mammals. Sensitivity of mitochondrial metabolism to ADP also changes with exercise. It is currently unknown whether similar mechanisms underpin regulation of fuel use during shivering, but I predicted that sensitivities to ADP and L-carnitine would be greater in highlanders than lowlanders and increase with acclimation. To address this question, I examined mitochondrial sensitivity to substrates involved in the fat oxidation pathway in low- and high- altitude deer mice born and raised in common laboratory conditions. Mice were also acclimated to high altitude condition of cold hypoxia to examine if the plasticity of these traits were affected by altitude ancestry. Consistent with previous findings, both high and lowland mice increased their cold-induced V̇O2max following cold hypoxia acclimation and rely primarily on lipids to fuel thermogenesis. High- and low-altitude deer mice responded differently to chronic cold hypoxia with highlanders showing a ~7-fold greater ADP sensitivity than lowlanders following acclimation. In contrast to the expected outcome, highlander deer mice tended to have a reduced sensitivity to L-carnitine compared to lowlanders that approached statistical significance. Neither sensitivity to palmitoylcarnitine sensitivity nor mitochondrial expression of FAT/CD36, thought to aid in mitochondrial fat delivery, showed differences between population or changes with acclimation, indicating that limitations to lipid oxidation during shivering likely occur at, or upstream of, CPT-I in the deer mouse. / Thesis / Master of Science (MSc) / Some animals can survive extremely harsh climates, such as high altitude. High altitude is characterized by unremitting cold and thin air, and these challenges can constrain aerobic activities in mammals. The North American deer mouse can thrive at high altitude by actively generating large amounts of body heat in a process known as thermogenesis. The deer mouse relies primarily on fats as fuel to support thermogenesis, but the cellular mechanisms that regulate the use of lipids to power thermogenesis remain unclear. To address this question, I induced shivering in deer mice from both high- and low-altitude populations that I exposed to simulated high- or low-altitude conditions. I then examined the effects of these treatments on the ability of shivering muscle to consume oxygen and fuel for thermogenesis. My thesis contributes to the current understanding of how mammals manage their energy supply to survive in a challenging environment.

Small UAV?s and flight vehicles in other atmospheres such as Mars are characterized by low Reynolds numbers. Low Reynolds number airfoil testing has been difficult to achieve and there are few centers that can accomplish this task. This study is an effort to develop a flight test system that will enable low Reynolds number tests to be performed with a simple glider design. The concept is to develop a high altitude glider that will be transported to altitudes reaching 100,000 feet or more by a helium filled balloon. At altitude, the glider will be released and will perform flight experiments as it descends. This region of Earth?s atmosphere, ?near space? has the conditions desired for low Reynolds number testing as well as similar properties to the surface of Mars. With the knowledge gained from this experiment, a better understanding of accomplishing flight on Mars may be attained.

No description available.

Hypoxia is a major stressor at high altitudes that limits tissue oxygen availability. High altitude environments are also extremely cold which increases thermogenic demand. Small mammals living at high altitude face the competing energetic challenge of maintaining thermogenesis in a hypoxic environment that can impair aerobic ATP supply. It has been suggested that hypoxia-induced impairments in ATP synthesis capacity and cold-induced increases in thermogenic demand could be counteracted by an increase in tissue oxidative capacity and/or fuel selection. As the organelle that consumes oxygen to produce ATP, changes in mitochondrial physiology can help offset physiological impairments at high altitudes. We explored this hypothesis in North American deer mice (Peromyscus maniculatus), from populations native to high and low altitude. We compared mitochondrial volume densities, intracellular distribution, respiratory capacities, enzyme activities of the mitochondrial complexes, capillarity, and fibre-type distribution in skeletal and cardiac muscles. To examine potential changes to mitochondrial physiology at high altitudes deer mice (P. maniculatus) were acclimated to: warm (25°C) normoxia; warm hypoxia (simulated altitude of 4300m); cold (5°C) normoxia; and cold + hypoxia. In skeletal muscle, highlanders had higher mitochondrial volume densities than lowlanders, entirely due to an increased abundance of mitochondria in a subsarcolemmal location next to capillaries. Mitochondria from highland mice also had higher mitochondrial respiratory capacities and cytochrome c oxidase activity in control conditions, but these values converged after hypoxia acclimation. Cold acclimation restored pyruvate and fatty acid respiratory capacity to control levels in highland mice, which also showed an increase in mitochondrial uncoupling. Cold increased respiratory capacities in lowland mice. Acclimation to cold+hypoxia did not change mitochondrial physiology beyond cold alone and appeared to counteract the effects of hypoxia on highland mice. In cardiac muscle highland mice had higher respiratory capacities, but after hypoxia acclimation lowland mice significantly increased respiratory capacities. In response to hypoxia, highland mice increased the relative capacity to oxidize carbohydrates compared to fatty acids. Our results suggest that both highland ancestry and plasticity affect mitochondrial physiology, and likely contributes to performance at high altitudes. / Thesis / Doctor of Philosophy (PhD)

Hypoxia encountered at high altitude (HA) can limit energy production via aerobic metabolism in animals. Carbohydrate oxidation (CHO) has a greater ATP yield/mole O2 than fat oxidation, and HA-native deer mice show an increased reliance on CHO during submaximal exercise after hypoxia acclimation as an O2-saving strategy. However, hypoxia acclimation does not increase glycolytic capacity in muscle. We therefore tested the hypothesis that altered metabolic regulation of the CHO pathway allows HA mice to achieve higher rates of CHO during submaximal exercise. The objective of our study was to identify the effects of hypoxia acclimation on the regulation of two key proteins in the CHO pathway and their activation with exercise. Using first generation (G1) laboratory born and raised HA deer mice acclimated to normoxia or chronic hypoxia, we examined the metabolic regulation of muscle glucose uptake by glucose transporter (GLUT) 4 and of pyruvate oxidation by pyruvate dehydrogenase (PDH). The gastrocnemius was electrically stimulated in situ under anaesthesia and acute normoxia at two submaximal workloads relative to maximal force production, which was measured using a force transducer. In frozen gastrocnemius following stimulation or rest, GLUT4 protein content was measured via Western blotting of the sarcolemmal membrane fraction and PDH activity was measured using a radiolabelled assay. We found no differences in sarcolemmal GLUT4 content with stimulation, but PDH activity was increased in hypoxia, indicating increased rates of carbohydrate breakdown at similar workloads after acclimation. These data were compared to data from wild HA deer mice sampled at their native altitude. In support of our hypothesis, these data show that the metabolic regulation of the carbohydrate oxidative pathway changes with acclimation to support higher CHO rates during submaximal exercise. These data will help uncover the mechanistic underpinnings responsible for the exercise fuel use strategies observed exclusively in HA-native mice. / Thesis / Master of Science (MSc) / At high altitude, oxygen availability is low and can be challenging for active animals. Preferential carbohydrate oxidation is a metabolic strategy used by high altitude-native deer mice to fuel exercise because of its high energy yield per oxygen consumed. Despite the increase in carbohydrate breakdown, the capacity for muscles to use carbohydrates did not change, suggesting that the regulation of this metabolic pathway may be changing instead. We measured the contributions of two proteins involved in carbohydrate metabolism in active muscle, pyruvate dehydrogenase (PDH) and glucose transporter 4 (GLUT4), at different muscle workloads and after acclimation to high altitude conditions. We found no differences in GLUT4 content, but PDH activity was higher in hypoxia-acclimated mice at similar intensities, indicating increased rates of carbohydrate breakdown after acclimation. These data suggest that the regulation of the carbohydrate metabolic pathway changes with acclimation to support higher rates of carbohydrate oxidation during exercise.