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  • 1
    Publication Date: 2011-08-19
    Description: This paper reviews some human and animal responses to space flight as well as in control models in simulations of weightlessness. Astronauts after space flight have been found to have a decreased red blood cell mass and plasma volume. The reason for these changes is unknown but appears to be caused primarily by a decrease in the need of red blood cells in the weightless condition. Similar though more moderate changes have been found in human subjects subjected to prolonged bed rest or water immersion. What happens to the red cell mass of laboratory rats flown in microgravity is not known but rats have shown an increase in the rate of random red cell loss in flight suggesting a probable decrease. Rat models subjected to either head-down suspension or restraint alone have shown a decrease in red blood cell masses and a decrease in their plasma volume.
    Keywords: LIFE SCIENCES (GENERAL)
    Type: Physiologist, Supplement (ISSN 0031-9376); 30; S-113 to
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  • 2
    Publication Date: 2011-08-16
    Description: Description of a high-sensitivity wide-bandwidth 10.6-micron heterodyne receiver for space and ground operational use. The receiver includes a cooled HgCdTe infrared mixer diode, a conical scanner for spatial tracking, an acquisition channel for spatial search and station alignment, and an automatic frequency-control channel to maintain a fixed laser frequency offset. The infrared mixer is designed to provide nearly quantum-noise-limited operation over an extended range of mixer temperature, bias voltage, and intermediate frequency. The resultant experimental receiver has a measured noise equivalent power of less than 10 to the minus 19th W/Hz over the 15- to 40-MHz i.f. band for mixer temperatures from 85 to 115 K, and less than 2 x 10 to the minus 19th W/Hz up to 140 K. Mixer 3-dB cutoff frequencies as high as 420 MHz were measured at a mixer temperature of 125 K. An analysis and engineering equations are given for receiver noise components, noise equivalent power, available mixer conversion gain, mixer transducer gain, and quantum-noise factor in terms of such factors as mixer parameters, quantum efficiency, mixer temperature, dynamic conductance, bias voltage, local oscillator power, and i.f. amplifier characteristics.
    Keywords: COMMUNICATIONS
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  • 3
    Publication Date: 2011-08-19
    Description: Hematologic studies were performed on a group of large and small rats which were sacrificed after flying in life sciences shuttle engineering flight SL-3. The results are presented on flight (F) and control (C) 200 gm rats. The small flight animals demonstrated a significant increase in hematocrits, red blood cell counts, hemoglobins and peripheral blood percentages of neutrophils as well as a decrease in percentage of lymphocytes. Erythropoietin (Ep) determinations were similar for the two groups as were the bone marrow an spleen differential counts. In vitro cultures for erythroid colonies of bone marrow showed that in response to different doses of Ep, in all cases where differnces were statistically significant, the F rats had increased colony counts. The changes in red cell parameters could be caused by a decrease in plasma volume. However, no isotopic studies were possible on this flight and this lack points up the need for such studies to determine the red cell mass and plasma volume.
    Keywords: LIFE SCIENCES (GENERAL)
    Type: Physiologist, Supplement (ISSN 0031-9376); 28; S-195
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  • 4
    Publication Date: 2019-06-28
    Description: The effect of a 7-day suspension in a jacket and harness with 20-deg head-down tilt on body weight, food and water consumption, and hematological parameters is investigated experimentally in male Sprague-Dawley rats weighing 150-175 g. The results are presented in graphs and compared with those for unsuspended controls and with published data on rats and humans exposed to microgravity in space flight. Suspended rats are found to have reduced red-blood-cell mass, erythropoiesis, plasma volume (leading to temporarily increased hematocrit), body weight, and food and water consumption; rightward-shifted oxyhemoglobin-dissociation curves; and unchanged platelet count, leucocyte count or PHA reactivity, and red-blood-cell shape distribution. Since many of these effects are also seen in space flight, the present experimental model is considered a promising technique for simulating the hematopoietic effects of microgravity at 1 g.
    Keywords: LIFE SCIENCES (GENERAL)
    Type: Aviation, Space, and Environmental Medicine (ISSN 0095-6562); 56; 419-426
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  • 5
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    In:  Other Sources
    Publication Date: 2019-06-27
    Description: Various factors which are important in the regulation of erythropoiesis have been studied in dehydrated mice in the belief that some information would be gained relevant to the erythropoietic effects of space flight. Dehydration reduced the plasma volume and, because changes in red cell volume were minimal, the hematocrit was elevated. Thus a state of relative erythrocytosis was produced. Understanding of the mechanism whereby these changes decreased red cell production is uncertain and appears to differ somewhat from the erythroid suppression seen following elevation of the hematocrit in animals with an absolute erythrocytosis. It is suggested that factors outside of the normal erythropoietic control pathway (such as energy balance) may play an important role in the decrease in red cell volume seen in man following space flight.
    Keywords: LIFE SCIENCES (GENERAL)
    Type: Acta Astronautica; 6; May-June
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  • 6
    Publication Date: 2019-06-28
    Description: Rats exposed to antiorthostatic, hypokinesia showed the following effects which are comparable to those seen in man during or after space flight: weight loss, reduced food and water consumption, transient increases in peripheral hematocrit and RBC count, decreasing MCV and reduced reticulocyte count. In addition, the hemoglobin P50 was shifted to the right. A significant shortening of RBC t1/2 was only seen after suspension. Changes in leukocyte and platelet numbers in suspended rats were also comparable to those in man during space flight, but leukocyte PHA sensitivity in rats showed no consistent alteration. The results demonstrate that this model reproduces many of the hematological effects of space flight and has potential as a tool in understanding the hematopoietic response to zero gravity.
    Keywords: LIFE SCIENCES (GENERAL)
    Type: Physiologist, Supplement (ISSN 0031-9376); 26; S-133
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  • 7
    Publication Date: 2019-07-13
    Description: Review of infrared coherent detection processes. Three receivers are described which were built with the primary goal of exploiting quantum noise limited heterodyne detection in a spectral region where atmospheric transmission characteristics are favorable. The combination of high power, high efficiency carbon dioxide lasers, coherent heterodyne receivers with sensitivities approaching the quantum noise limit, and low-loss atmospheric transmission have presented new possibilities in infrared communications and radar. In particular, high sensitivity 10.6 micrometer heterodyne receivers with wide IF bandwidths have been developed.
    Keywords: COMMUNICATIONS
    Type: Electro-Optical Systems Design Conference; Sep 14, 1971 - Sep 16, 1971; New York, NY
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  • 8
    Publication Date: 2019-07-12
    Description: The cause of the red cell mass (RCM) deficit, which occurs in rats during suspenion, is investigated. The experimental conditions and procedures, in which male Sprague-Dawley rats are subjected to antiorthostatic hyypokinetic/hypodynamia and changes in RCM are monitored, are described. The influences of stress, reduced food and water consumption, and antiorhostatic posture on RCM are analyzed. Changes in body weight, RCM, radioiron incorporation, red blood cells (RBC), and reticulocytes, for the rats after head-down suspension are graphically presented; only the changes in RBC are related to the antiorthostatic posture. The data reveal that anemia is primarily caused by reduced food and water consumption and secondly by restricted movements.
    Keywords: LIFE SCIENCES (GENERAL)
    Type: Aviation, Space, and Environmental Medicine (ISSN 0095-6562); 57; 36-44
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