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  • Other Sources  (7)
  • NASA Technical Reports  (7)
  • Aerospace Medicine  (4)
  • Energy Production and Conversion  (3)
  • 1995-1999  (7)
  • 1950-1954
  • 1
    Publication Date: 2011-08-24
    Description: The purpose was to investigate the mechanism for the excessive exercise hyperthermia following deconditioning (reduction of physical fitness). Rectal (Tre) and mean skin (Tsk) temperatures and thermoregulatory responses were measured in six men [mean (SD) age, 32 (6) years; mass, 78.26 (5.80) kg; surface area, 1.95 (0.11) m2; maximum oxygen uptake (VO2max), 48 (6) ml.min-1.kg-1; whilst supine in air at dry bulb temperature 23.2 (0.6) degree C, relative humidity 31.1 (11.1)% and air speed 5.6 (0.1) m.min-1] during 70 min of leg cycle exercise [51 (4)% VO2max] in ambulatory control (AC), or following 6 h of chair rest (CR), 6 degree head-down bed rest (BR), and 20 degree (WI20) and 80 degree (WI80) foot-down water immersion [water temperature, 35.0 (0.1) degree C]. Compared with the AC exercise delta Tre [mean (SD) 0.77 (0.13) degree C (*P 〈 0.05), after WI80 0.96 (0.13) degree C*, and after WI20 1.03 (0.09) degree C*. All Tsk responded similarly to exercise: they decreased (NS) by 0.5-0.7 degree C in minutes 4-8 and equilibrated at +0.1 to +0.5 degree C at 60-70. Skin heat conductance was not different among the five conditions (range = 147-159 kJ.m-2.h-1.degree C-1). Results from an intercorrelation matrix suggested that total body sweat rate was more closely related to Tre at 70 min (Tre70) than limb sweat rate or blood flow. Only 36% of the variability in Tre70 could be accounted for by total sweating, and less than 10% from total body dehydration. It would appear that multiple factors are involved which may include change in sensitivity of thermo- and osmoreceptors.
    Keywords: Aerospace Medicine
    Type: European journal of applied physiology and occupational physiology (ISSN 0301-5548); Volume 72; 4; 303-9
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  • 2
    Publication Date: 2011-08-24
    Description: PURPOSE: To determine weight (water) loss levels for onset of muscular strength and endurance changes during deconditioning. METHODS: Seven men (27-40 yr) performed maximal shoulder-, knee-, and ankle-joint isometric (0 degree.s(-1) load) and isokinetic (60 degrees, 120 degrees, 180 degrees.s(-1) velocity) exercise tests during ambulatory control (AC), after 6 h of 6 degrees head-down tilt (HDT; dry-bulb temp. = 23.2 +/- SD 0.6 degrees C, relative humidity = 31.1+/- 11.1%) and after 6 h of 80 degrees foot-down head-out water immersion (WI; water temp. = 35.0 +/- SD 0.1 degree C) treatments. RESULTS: Weight (water) loss after HDT (1.10 +/- SE 0.14 kg, 1.4 +/- 0.2% body wt) and WI (1.54+/- 0.19 kg, 2.0 +/- 0.2% body wt) were not different, but urinary excretion with WI (1,354 +/- 142 ml.6 h(-1)) was 28% greater (p 〈 0.05) than that of 975 +/- 139 ml.6 h(-1) with HDT. Muscular endurance (total work; maximal flexion-extension of the non-dominant knee at 180 degrees.s(-1) for 30 s) was not different between AC and the WI or HDT treatments. Shoulder-, knee-, and ankle-joint strength was unchanged except for three knee-joint peak torques: AC torque (120 degrees.s(-1), 285 +/- 20 Nm) decreased to 268 +/- 21 Nm (delta = -6%, p 〈 0.05) with WI; and AC torques (180 degrees.s(-1), 260 +/- 19 Nm) decreased to 236 +/- 15 Nm (delta = -9%, p 〈 0.01) with HDT, and to 235 +/- 19 Nm (delta = -10%, p 〈 0.01) with WI. CONCLUSION: Thus, the total body hypohydration threshold level for shoulder- and ankle-joint strength and endurance decrements is more than 2% body weight (water) loss, while significant reduction in knee-joint muscular strength-endurance occurred only at moderate (120 degrees.s(-1) and lighter (180 degrees.s(-1)) loads with body weight loss of 1.4-2.0% following WI or HDT, respectively. These weight (water) losses and knee-joint strength decrements are somewhat less than the mean weight loss of 2.6% and knee-joint strength decrements of 6-20% of American astronauts after Skylab flights to 84 d.
    Keywords: Aerospace Medicine
    Type: Aviation, space, and environmental medicine (ISSN 0095-6562); Volume 67; 1; 46-51
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  • 3
    Publication Date: 2004-12-03
    Description: The Ohio Aerospace Institute and the NASA Lewis Research Center are designing and building a solar-cell calibration facility, the Photovoltaic Engineering Testbed (PET) to fly on the International Space Station to test advanced solar cell types in the space environment. A wide variety of advanced solar cell types have become available in the last decade. Some of these solar cells offer more than twice the power per unit area of the silicon cells used for the space station power system. They also offer the possibilities of lower cost, lighter weight, and longer lifetime. The purpose of the PET facility is to reduce the cost of validating new technologies and bringing them to spaceflight readiness. The facility will be used for three primary functions: calibration, measurement, and qualification. It is scheduled to be launched in June of 2002.
    Keywords: Energy Production and Conversion
    Type: Proceedings of the Seventh International Space University Alumni Conference; 49-51; NASA/CP-1999-209199
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  • 4
    Publication Date: 2019-07-17
    Description: The losses of aerobic power and orthostatic tolerance are significant effects of manned C) spaceflight that can negatively impact crew health and safety. Daily acceleration and aerobic training may ameliorate these effects. To determine the influence of passive intermittent +Gz acceleration (PA) training and active acceleration + interval exercise (AE) training on work 0 0 capacity and the acute (1 min) response to 70 deg head-up tilt, 6 men (X-Bar SD: age, 33 +/- 6 y; height, 178.3 +/- 4.6 cm; mass, 86.3 +/- 6.6 kg) participated in two 3-wk training protocols. It was hypothesized that PA and AE training would improve orthostatic tolerance and that the addition of aerobic conditioning, would not alter this effect.
    Keywords: Aerospace Medicine
    Type: Exploring Space; May 20, 2000 - May 26, 2000; Santorini; Greece
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  • 5
    Publication Date: 2019-07-13
    Description: The purpose was to investigate the mechanism for the excessive exercise hyperthermia following deconditioning (reduction of physical fitness). Rectal (T(sub re)) and mean skin (T(bar)(sub sk)) temperatures and thermoregulatory responses were measured in six men [mean (SD) age, 32 (6) years; mass, 78.26 (5.80) kg; surface area, 1.95 (0.11) sq m; maximum oxygen uptake (VO2max), 48 (6) ml/min/kg; whilst supine in air at dry bulb temperature 23.2 (0.6)C, relative humidity 31.1 (11.1)% and air speed 5.6 (0.1) m/min] during 70 min of leg cycle exercise [51 (4)% VO2max] in ambulatory control (AC), or following 6 h of chair rest (CR), 6deg head-down bed rest (BR), and 20deg (W120) and 80deg (W180) foot-down water immersion [water temperature, 35.0 (0.1) C]. Compared with the AC exercise (Delta)T(sub re) [mean (SD) 0.77 (0.13)C], (Delta)T(sub re), after CR was 0.83 (0.08)C (NS), after BR 0.92 (0.13)C (*P 〈0.05), after W180 0.96 (0.13)C*, and after W120 1.03 (0.09)C*. All T(sub sk) responded similarly to exercise: they decreased (NS) by 0.5-0.7 C in minutes 4-8 and equilibrated at +0.1 to +0.5 C at 60-70. Skin heat conductance was not different among the five conditions (range = 147-159 kJ/sq/C. Results from an intercorrelation matrix suggested that total body sweat rate was more closely related to T(sub re) at 70 min (T(sub re70)) than limb sweat rate or blood flow. Only 36% of the variability in T(sub re70) could be accounted for by total sweating, and less than 10% from total body dehydration. It would appear that multiple factors are involved which may include change in sensitivity of thermo- and osmoreceptors.
    Keywords: Aerospace Medicine
    Type: Eur Journal of Applied Physiology; 72; 303-309
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  • 6
    Publication Date: 2019-07-13
    Description: The advances in solar cell efficiency, radiation tolerance, and cost over the last decade are reviewed. Potential performance of thin-film solar cells in space are discussed, and the cost and the historical trends in production capability of the photovoltaics industry are considered with respect to the requirements of space power systems. Concentrator cells with conversion efficiency over 30%, and nonconcentrating solar cells with efficiency over 25% are now available, and advanced radiation-tolerant cells and lightweight, thin-film arrays are both being developed. Nonsolar applications of solar cells, including thermophotovoltaics, alpha- and betavoltaics, and laser power receivers, are also discussed.
    Keywords: Energy Production and Conversion
    Type: NASA-TM-112758 , NAS 1.15:112758 , AIAA Paper 95-0027 , Aerospace Sciences; Jan 09, 1995 - Jan 12, 1995; Reno, NV; United States|Journal of Propulsion and Power; 12; 5; 835-841
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  • 7
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    In:  Other Sources
    Publication Date: 2019-07-17
    Description: Mars is a challenging environment for the use of solar power. The implications of the low temperatures and low light intensity, solar spectrum modified by dust and changing with time of day and year, indirect sunlight, dust storms, deposited dust, wind, and corrosive peroxide-rich soil are discussed with respect to potential photovoltaic power systems. The power systems addressed include a solar-powered rover vehicle and a human base. High transportation costs dictate high efficiency solar cells or alternatively, a 'thin film' solar cell deposited on a lightweight plastic or thin metal foil.
    Keywords: Energy Production and Conversion
    Type: The Sixth Alumni Conference of the International Space University; 69; NASA-CP-3355
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