ASHRAE Standard 139 provides parameters which are used in the desiccant industry to calculate the performance of a desiccant dehumidifier. This performance can be obtained from any manufacturer by means of performance curves or selection software. However, these performance parameters are generally rated at sea-level conditions. Although some manufacturers provide a means for estimating the performance at altitude based on sea-level conditions, there is no set methodology that is accepted by all. The scope of this project involves investigating how the performance parameters are affected by altitude and develop a general methodology that can be applied to any desiccant wheel. Mississippi State University and the National Renewable Energy Laboratory both conducted tests and compared the results. It was found that, by keeping mass flow rate, inlet temperature, and inlet humidity ratio constant between sea-level and altitude, the pressure drop through the wheel was influenced the most by altitude.

Animals who live in the high-altitude environment are faced with the harsh conditions of low oxygen availability. This can make it difficult to perform daily tasks that require aerobic metabolism. However, deer mice (Peromyscus maniculatus) have evolved physiological adaptions that allow populations to survive in the high-altitude environment. One activity important for survival is aerobic locomotion and the rapid recovery of muscle metabolism after a bout of exercise. Hypoxia acclimated high-altitude mice have a greater reliance on carbohydrates to power exercise than low altitude mice and show a significant depletion of muscle glycogen. However, it is unclear how quickly after exercise is finished that these mice can replenish muscle glycogen stores. The gastrocnemius muscle of high-altitude deer mice has a more aerobic phenotype and a greater capacity to oxidize lipids than in low altitude mice. This suggests that high altitude mice may recover more quickly from exercise than their lowland counterparts due to a greater capacity to power glycogen replenishment through aerobic metabolism using the lipids stored in muscle as intramuscular triglycerides (IMTG). Using low- and high-altitude native deer mice born and raised in common lab conditions and acclimated to chronic hypoxia, I determined changes in oxygen consumption (VO2) following aerobic exercise and sampled skeletal muscle at various time points during recovery to examine changes in key metabolites, including glycogen and IMTG. I found there was depletion in glycogen stores during exercise in lowlanders and glycogen did return to resting levels following 90 minutes of recovery. In contrast, IMTG’s did not significantly change with exercise or during the recovery period in either population. These data suggest that muscle recovery from aerobic exercise may be influenced by altitude ancestry in deer mice. / Thesis / Master of Science (MSc)

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Live high - train low altitude camps can enhance endurance power at sea level by 1-2% (Levine & Stray-Gunderson, 1997). More convenient methods to simulate altitude exposure are now available, but their effects on performance are less well characterized. In this study, we investigated intermittent hypoxic training (IHT) using an Hypoxicator, a device that produces oxygen-depleted air that athletes breathe intermittently through masks in a small group at a central venue. Twelve highly-competitive, male cyclists and multi-sport athletes (IHT group) underwent IHT in two, four-week bouts separated by eight weeks. Bout one consisted of 20 one-hour exposures and bout two 18 exposures where normal and low-oxygenated air was breathed in alternating five-minute intervals. The percentage of oxygen inhaled by the subjects was adjusted to produce an oxygen saturation of the blood of 88-92% in the first week of the study, decreasing to 76-80% (equivalent to an altitude of approximately 6000m) in the final week. A control group of 13 similar athletes did not use the Hypoxicator. Performance trials and blood tests were at four-week intervals; there were 3 trials (familiarization and reliability) before use of the Hypoxicator, 3 trials after to determine the effect of simulated altitude, then a second four-week exposure and one more trial. The measures of performance were mean power in a 16-km time trial on a Kingcycle ergometer (IHT group only) and power in a lactate-threshold test at 3 mmol/L above baseline (both groups). The measures from the blood tests were haemoglobin and haematocrit. There was a gradual but erratic improvement in performance in the time trial and lactate threshold tests over the course of the study in both groups, indicating an improvement through training. Relative to the last baseline test (Trial 3), the IHT group showed a 0.6% decrease in mean power over and above the effect of training in the 16-km time trial in Trial 4, nine days after last use of IHT. There was a 0.3% increase in mean power independent of the training effect in Trial 7, after the second round of altitude exposure. Uncertainty in these changes in performance was ±3.5% (95% confidence interval). The changes in lactate threshold in trials 4 and 7 indicate a possible improvement as a result of IHT exposure. Uncertainty in these changes was ±4.0%. There were negligible changes in the haemoglobin and hematocrit of either group at any time. There was small evidence of high responders, who were probably subjects with the DD genotype for the angiotensin converting enzyme gene. The time exposed to IHT had no bearing on performance and there was no evidence "peak" in results at either four or eight weeks after exposure to IHT. In summary, four weeks of IHT exposure probably resulted in a trivial effect on 16-km time-trial performance and the effort-independent measures provided no further clear-cut evidence of a performance improvement.

Live high - train low altitude camps can enhance endurance power at sea level by 1-2% (Levine & Stray-Gunderson, 1997). More convenient methods to simulate altitude exposure are now available, but their effects on performance are less well characterized. In this study, we investigated intermittent hypoxic training (IHT) using an Hypoxicator, a device that produces oxygen-depleted air that athletes breathe intermittently through masks in a small group at a central venue. Twelve highly-competitive, male cyclists and multi-sport athletes (IHT group) underwent IHT in two, four-week bouts separated by eight weeks. Bout one consisted of 20 one-hour exposures and bout two 18 exposures where normal and low-oxygenated air was breathed in alternating five-minute intervals. The percentage of oxygen inhaled by the subjects was adjusted to produce an oxygen saturation of the blood of 88-92% in the first week of the study, decreasing to 76-80% (equivalent to an altitude of approximately 6000m) in the final week. A control group of 13 similar athletes did not use the Hypoxicator. Performance trials and blood tests were at four-week intervals; there were 3 trials (familiarization and reliability) before use of the Hypoxicator, 3 trials after to determine the effect of simulated altitude, then a second four-week exposure and one more trial. The measures of performance were mean power in a 16-km time trial on a Kingcycle ergometer (IHT group only) and power in a lactate-threshold test at 3 mmol/L above baseline (both groups). The measures from the blood tests were haemoglobin and haematocrit. There was a gradual but erratic improvement in performance in the time trial and lactate threshold tests over the course of the study in both groups, indicating an improvement through training. Relative to the last baseline test (Trial 3), the IHT group showed a 0.6% decrease in mean power over and above the effect of training in the 16-km time trial in Trial 4, nine days after last use of IHT. There was a 0.3% increase in mean power independent of the training effect in Trial 7, after the second round of altitude exposure. Uncertainty in these changes in performance was ±3.5% (95% confidence interval). The changes in lactate threshold in trials 4 and 7 indicate a possible improvement as a result of IHT exposure. Uncertainty in these changes was ±4.0%. There were negligible changes in the haemoglobin and hematocrit of either group at any time. There was small evidence of high responders, who were probably subjects with the DD genotype for the angiotensin converting enzyme gene. The time exposed to IHT had no bearing on performance and there was no evidence "peak" in results at either four or eight weeks after exposure to IHT. In summary, four weeks of IHT exposure probably resulted in a trivial effect on 16-km time-trial performance and the effort-independent measures provided no further clear-cut evidence of a performance improvement.

xvii, 174 p. : ill. A print copy of this thesis is available through the UO Libraries. Search the library catalog for the location and call number. / During acute altitude exposure, humans maintain higher skin temperature and lower core body temperature. However, the role of cutaneous vascular regulation in these thermoregulatory differences is unclear. Therefore, the purpose of these studies was to investigate the impact of altitude exposure on reflex control of skin blood flow and core temperature during cold exposure. In Chapter IV, the effects of hypoxia and hypocapnia on cutaneous vasoconstriction during mild cold exposure were investigated. We found that hypoxia stimulates cutaneous vasodilation in men whereas skin blood flow is unaltered in women. However, during whole body cooling skin blood flow is upward shifted in both sexes. The development of hypocapnia does not affect the vascular response to hypoxia in either sex, but reduces the magnitude of cutaneous vasoconstriction during cold exposure by 50% in women. In Chapter V, we studied the timecourse of α-adrenergic blockade by yohimbine in the cutaneous circulation and how the duration of cold exposure modulates cotransmitter-mediated vasoconstriction during cold stress. We found that yohimbine produces functional α-adrenergic blockade within 30 minutes of initial delivery and completely abolishes reflex cutaneous vasoconstriction during mild cold stress. This latter finding was surprising, and an additional protocol demonstrated that cotransmitter-mediated vasoconstriction only participates in the vascular response to cold stress when the exposure is more prolonged. In Chapter VI, the effects of hypoxia on cutaneous vasoconstrictor mechanisms and core cooling rate were tested during more prolonged and severe cold stress. In contrast to our findings during brief cold exposure, we showed that cutaneous vasoconstriction during prolonged cold stress is potentiated by hypoxia and abolishes hypoxic vasodilation. Moreover, increased cotransmitter-mediated vasoconstriction appears to account for this response. Hypoxia had no effect on core cooling rate during severe cold exposure. The selective potentiation of cotransmitter-mediated vasoconstriction observed during hypoxia in Chapter VI provided the basis for Chapter VII. This study was designed to test the effect of hypoxia on cutaneous vascular responsiveness to peripherally stimulated sympathetic vasoconstriction. The results demonstrated that α-adrenergic vasoconstrictor transduction is not affected by hypoxia, and that stimulation of adrenergic nerves with tyramine does not elicit cotransmitter-mediated vasoconstriction in skin. / Adviser: John R. Halliwill

Submitted by João Arthur Martins (joao.arthur@ufpe.br) on 2015-03-03T20:05:09Z No. of bitstreams: 2 license_rdf: 1232 bytes, checksum: 66e71c371cc565284e70f40736c94386 (MD5) Dissertaçao Claudia Vergetti Silva .pdf: 4653527 bytes, checksum: 88891d165baab9ccd0a8cbc47d7167f2 (MD5) / Made available in DSpace on 2015-03-03T20:05:09Z (GMT). No. of bitstreams: 2 license_rdf: 1232 bytes, checksum: 66e71c371cc565284e70f40736c94386 (MD5) Dissertaçao Claudia Vergetti Silva .pdf: 4653527 bytes, checksum: 88891d165baab9ccd0a8cbc47d7167f2 (MD5) Previous issue date: 2012-10-09 / Todas as obras de engenharia civil usam medidas de distâncias horizontais e verticais. No caso das verticais as diferenças de altura na maioria das obras podem ser apenas relativas, tem exigências de precisão variáveis que são mais rigorosas quando envolvem escoamento de líquidos, e são determinadas normalmente pelo método de nivelamento geométrico que fornece as altitudes ortométricas. Atualmente também estão se utilizando altitudes obtidas do GNSS (Global Navigation Satellite System) por questões de economia e produtividade nas obras, mas elas são medidas geométricas em relação à superfície de um elipsóide, sendo que para obras de drenagem e hidráulicas a referência adequada é uma superfície equipotencial da gravidade ou o geóide. A altitude ortométrica de um ponto também pode ser obtida através da altitude geométrica desde que se conheça a ondulação geoidal do mesmo. Como essa transformação contém os erros inerentes da determinação da ondulação geoidal essa metodologia tem sido questionada como não sendo confiável para uso em obras de engenharia civil. Este trabalho tem por finalidade analisar e propor o uso da altitude geométrica para obras de engenharia de modo direto, sem necessidade de ser feita a sua transformação para a altitude ortométrica. Para essas análises foram usados dois conjuntos de dados. Um foi de uma área levantada dentro e no entorno do perímetro da UFPE (Universidade Federal de Pernambuco). O outro foi de dados obtidos no levantamento do trecho Norte do canal de Transposição do Rio São Francisco. Todos os dados foram analisados quanto ao processamento, precisões obtidas e procedimentos de campo para identificar os erros inerentes na obtenção da altitude geométrica. Finalmente são sugeridos alguns cuidados básicos, restrições e procedimentos no uso das altitudes geométricas em determinadas obras de engenharia civil.

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Orientador: Paulo de Oliveira Camargo / Resumo: A definição e determinação da coordenada vertical de pontos da superfície terrestre é alvo de pesquisas atualmente. As técnicas de posicionamento Global Navigation Satellite System (GNSS) proporcionam o conhecimento das altitudes de forma rápida e fácil; porém, a componente fornecida por estas técnicas possui caráter geométrico, ou seja, a altitude corresponde à distância normal entre o ponto mensurado e o elipsoide de revolução. Esta altitude tem sua importância, porém não possui caráter físico. Em obras de engenharia, é fundamental o conhecimento da altitude física, pois é a do sentido de escoamento da água. Este fator físico corresponde ao geopotencial, que quando relacionado com dados gravimétricos resulta em uma altitude física que representa a distância entre a superfície equipotencial do ponto de interesse e a superfície equipotencial de referência. Em 2015, a International Association of Geodesy (IAG) publicou uma resolução de fundamental importância na integração dos sistemas de altitudes entre os países, visando à formação de um Sistema Internacional de Referência Altimétrico, o International Height Reference System (IHRS). Dessa forma, para que as altitudes possam ser integradas ao IHRS é necessário calcular o valor do geopotencial. Os dados gravimétricos disponíveis no estado de São Paulo possibilitaram o cálculo do geopotencial, uma vez que o estado possui distribuição gravimétrica homogênea, que é uma das sugestões de condições para determinar o valor do potenci... (Resumo completo, clicar acesso eletrônico abaixo) / Abstract: Knowledge the vertical coordinate of points of the terrestrial surface is currently under investigation. Global Navigation Satellite System (GNSS) techniques provide the heights quickly and easily; however, the component provided by these techniques has a geometric character, that is, the height corresponds to the normal distance between the measured point and the revolution ellipsoid. This height has its importance, but it does not have physical meaning. In engineering works, it is fundamental to know the physical height, because it is the one that the direction of water flow obeys. This physical factor corresponds to the geopotential, which when related to gravimetric data results in a physical height. Represents the distance between the equipotential surface of the point of interest and the equipotential reference surface. In 2015, the International Association of Geodesy (IAG) published a resolution of fundamental importance in the integration of height systems between countries, aiming at the formation of a global altimetric system, the International Height Reference System (IHRS). Thus, in order for the heights to be integrated into the IHRS, it is necessary to calculate the potential value. Thus, considering the importance of integrating Brazilian heights with a global system, the geopotential number for the PPTE and NEIA stations in the state of São Paulo was calculated. In these calculations were applied the Global Geopotential Models (GGMs) EIGEN-6C4, GECO, GOCO05c ... (Complete abstract click electronic access below) / Mestre

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