We have read with interest the short communication published by Segovia-Juarez et al., 2020 in Respiratory Physiology & Neurobiology establishing that high altitude reduces the infection rate of COVID-19 but not the case fatality rate in the Peruvian setting. We support this hypothesis, however there could be an important number of under registered deaths on account of a low rate of diagnostic tests performed per inhabitant and mostly in symptomatic patients (Pasquariello and Stranges, 2020). / Revisión por pares

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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)

These projects were conducted to determine the digestibility of forage diets with differing CP levels in llamas and alpacas. The Utah study was designed to compare llama and alpaca nutritional parameters to determine if nutritional recommendations for llamas can be directly extrapolated to alpacas. The first study evaluated the effects of forage quality on blood metabolites and nitrogen balance in mature, intact male llamas (n = 4, 36 ± 4.4 months, 87 ± 17 kg) at high altitude in Letanias, Bolivia (4,267 m = aprox.14,000 ft above sea level). A second experiment was conducted with eight adult gelded camelids (n = 8; 4 llamas, 24-36 months, 90 ± 10.7 kg; 4 alpacas, 24-36 months, 50 ± 4 kg) at Brigham Young University, Provo, UT (altitude 1370 m). Animals were randomly fed barley hay (B) and 80% barley/20% alfalfa hay (BA). A fresh cut grass pasture (P) was included as the third forage for Bolivian llamas. Animals were housed in metabolism crates and diets were fed for a 7 d adjustment period followed by a 5 d collection period. Feed, feed refusal, feces and urine were collected, dried and N content determined by combustion analysis. Venous blood samples were collected on d 12 at 30 min intervals over a 6 h period. Plasma was harvested and analyzed for electrolytes (Na, K, Cl, Ca, Ca++, P, Mg) and metabolites (glucose, non- esterified fatty acids (NEFAs), urea N, creatinine, albumin, total protein (TPP), osmolality (Osm)). Llamas and alpacas demonstrated differences with respect to nitrogen metabolism when consuming forage diets with differing protein concentration. Llamas showed a N maintenance requirement of 0.75 g crude N/ W0.75. Using the standard CP to digestible protein (DP) conversion factor of 0.8, llamas required 0.60 digestible N/W0.75. When consuming the same high protein barley alfalfa diet, llamas had a much greater increase in N retention than alpacas. These species differences indicate that alpacas have a higher N requirement to meet metabolic needs, and extrapolations with respect to nitrogen requirements and balance are not valid between llamas and alpacas. In the Bolivian llama trial, locally grown and harvested hycrested and Siberian wheat grass pasture (P), barley (B), and barley80%/alfalfa20% (BA) hays were fed. The Bolivian llamas were in negative N balance when fed the B and P diets. Dry matter digestibility was greater with the B and BA than P forage, and N digestibility was significantly higher with BA than either the B or P forages. Nitrogen maintenance requirement for Bolivian llamas at 4,267 m was 0.58 compared to 0.75 g crude N/W0.75 for Utah llamas, an increased digestive efficiency and a lower N maintenance requirement at higher altitude.

Competition often requires teams that reside at sea level to compete against opponents whose residence is at a moderate altitude. This may pose a potential competitive disadvantage considering that moderate altitude may cause decrements in VO2max, distance covered, and time to exhaustion in endurance athletes. The purpose of this study was to examine the effect of altitude on game performance measures. Six NCAA Division I female soccer players (20.33 ± 1.21 y; 168 ± 6.45 cm; 62.5 ± 6.03 kg) were retrospectively examined. Comparisons were made between two competitions that were played at sea level (SL) within two weeks of a game played at a moderate altitude (1840 m) on game characteristics including high intensity running (HIR) and total distance covered (TDC). Analysis was performed on these six players who met a threshold of playing sixty or more minutes in each competition. A 10-Hz global positioning system (GPS) was used to measure distance and velocity. The rate of TDC and HIR during the game (m?min-1) and percentage of time at HIR during competition were evaluated. The two games at SL were averaged to establish baseline performance and the mean results were compared with the single game played at altitude. Paired samples t-tests were performed to determine if any mean differences existed between performance at altitude and sea level. Significant differences (p < 0.05) were seen in minutes played between the games at SL (74.23 ± 2.93 min) versus altitude (83.24 ± 5.27 min). The relative distance rate during the game at altitude was lower at altitude (105.77 ± 10.19 m?min-1) than at SL (120.55 ± 8.26 m?min-1). HIR rate was greater at SL (27.65 ± 9.25 m?min-1) compared to altitude (25.07 ± 7.66 m?min-1). The percent of time spent at high intensity was not significantly different (p = 0.064), yet tended to be greater at sea level (10.4 ± 3.3%) than when they performed at altitude (9.1 ±2.2%). Soccer performance at a moderate altitude appears to reduce the rate at which players run throughout the competition, as well as their rate at a high intensity. Results suggest that teams that reside at SL may be at a competitive disadvantage when competing at altitude.

<p> Prairie mounds from the general area of Foremost-Cypress Hills, Alberta, have been described. Various morphometric parameters, including relative and absolute altitude of the mounds, depth of their central depressions, orientation of breaches in their rims, angle of the bounding slopes, and distribution of surficial stones were measured. Several characteristics of the mounds were found to be widespread. Firstly, the mounds occur in elongate fields that correspond roughly to the 3,000 ft. contour interval. Secondly, surficial stones invariably have their greatest concentration on the rims of the mounds. Also the mounds are frequently separated by interrupted drainage channels. The bounding slopes of the mounds are asymmetrical, with west and north-west slopes being least steep. Interpretation of these morphological observations and a consideration of the various hypotheses of formation proposed in the literature leads to the conclusion that prairie mounds most likely originated by the differential melting of a stagnant ice mass in a manner proposed by Gravenor in 1955, and have subsequently been modified by mass-wasting processes. / Thesis / Master of Arts (MA)

<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)