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861.
862.
A.I. Podgorny I.M. Podgorny 《Advances in Space Research (includes Cospar's Information Bulletin, Space Research Today)》1997,19(12):1929-1932
The patterns of reconnection in the Earth magnetotail and in the solar corona above the active region are presented. The electric field and field-aligned currents (FAC) generation in the current sheet are discussed. 相似文献
863.
In November 2000, the National Aeronautics and Space Administration (NASA) and its partners in the International Space Station (ISS) ushered in a new era of space flight: permanent human presence in low-Earth orbit. As the culmination of the last four decades of human space flight activities. the ISS focuses our attention on what we have learned to date. and what still must be learned before we can embark on future exploration endeavors. Space medicine has been a primary part of our past success in human space flight, and will continue to play a critical role in future ventures. To prepare for the day when crews may leave low-Earth orbit for long-duration exploratory missions, space medicine practitioners must develop a thorough understanding of the effects of microgravity on the human body, as well as ways to limit or prevent them. In order to gain a complete understanding and create the tools and technologies needed to enable successful exploration. space medicine will become even more of a highly collaborative discipline. Future missions will require the partnership of physicians, biomedical scientists, engineers, and mission planners. This paper will examine the future of space medicine as it relates to human space exploration: what is necessary to keep a crew alive in space, how we do it today, how we will accomplish this in the future, and how the National Aeronautics and Space Administration (NASA) plans to achieve future goals. 相似文献
864.
L A Spomer 《Advances in Space Research (includes Cospar's Information Bulletin, Space Research Today)》1994,14(11):411-416
The major functions of soil relative to plant growth include retention and supply of water and minerals, provision of anchorage and support for the root, and provision of an otherwise adequate physical and chemical environment to ensure an extensive, functioning root system. The physical and chemical nature of the solid matrix constituting a soil interacts with the soil confinement configuration, the growing environment, and plant requirements to determine the soil's suitability for plant growth. A wide range of natural and manufactured terrestrial materials have proven adequate soils provided they are not chemically harmful to plants (or animals eating the plants), are suitably prepared for the specific use, and are used in a compatible confinement system. It is presumed this same rationale can be applied to planetary soils for growing plants within any controlled environment life support system (CELSS). The basic concepts of soil and soil-plant interactions are reviewed relative to using soils constituted from local planetary materials for growing plants. 相似文献
865.
V. Formisano V.I. Moroz H. Hirsch P. Orleanski G. Michel J. Lopez-Moreno E. Amata G. Bellucci G. Piccioni G. Chionchio A. Carusi A. Coradini P. Cerroni M.T. Capria F. Capaccioni A. Adriani M. Vitterbini F. Angrilli G. Bianchini B. Saggin S. Fonti E. Bussoletti D. Mancini L. Colangeli A. Grigoriev B. Moshkin V. Gnedykh I.A. Matsygorin D. Patsaev Yu.V. Nikolsky D.V. Titov L.V. Zasova I. Khatuntsev A. Kiselev G. Arnold H. Driesher M.I. Blecka R. Rodrigo J. Rodriguez-Gomez 《Advances in Space Research (includes Cospar's Information Bulletin, Space Research Today)》1996,17(12):61-64
Thin films containing a mixture of aliphatic (glycine) and aromatic (tryptophan or tyrosine) amino acids were exposed to a vacuum ultraviolet radiation (VUV) with wavelenghts 100–200 nm. Dipeptides (glycyl-tryptophan and glycyl-tyrosine) were synthesized in these conditions. We compared the actions of VUV and γ-radiation. Polymerization is an essential step in prebiological evolution and we have shown that this stage probably occured over an early Solar system history. 相似文献
866.
A A Tikhomirov S A Ushakova 《Advances in Space Research (includes Cospar's Information Bulletin, Space Research Today)》2001,27(9):1535-1539
Our experiments examined enhancing tolerance of the photosynthesizing component to possible deviations in thermal or illumination conditions inside a bioregenerative life support system (BLSS). In the event of one parameter getting beyond its optimum, the values of other parameters may ensure minimal damage to the plant component during the period of environmental stress. With wheat plants (one of key elements of the plant component) as an example the work considers whether it is possible to enhance thermal tolerance by varying light intensity. Increase of air temperature to 35 degrees C or 45 degrees C with light intensity of 60 W/m2 PAR has been shown to substantially inhibit the photosynthesis processes; at 150 W/m2 PAR photosynthesis decreases from 50% to 100%, respectively; when light intensity is increased to 240 W/m2 PAR photosynthesis increased more than 70% at 35 degrees C and decreased at 45 degrees C by only 20%. Thus, light intensity can be increased to avoid or decrease the inhibiting effect of high temperatures. On the other hand, tolerance of wheat plants to prolonged absence of light can be substantially enhanced by decreasing during this period air temperature to temperatures close to 0 degrees C. 相似文献
867.
Doppler imaging based on radar target precession 总被引:2,自引:0,他引:2
A unique form of target motion reminiscent of the precession of a rotating top is investigated. Images are generated with the radar looking either along the precession axis or orthogonally to it. Features of the two methods are discussed and demonstrated by imaging simulated point target scenes 相似文献
868.
H Houben R M Haberle R E Young A P Zent 《Advances in Space Research (includes Cospar's Information Bulletin, Space Research Today)》1997,19(8):1233-1236
The current Martian water cycle is extremely asymmetric, with large amounts of vapor subliming off a permanent north polar water ice cap in northern summer, but with no apparent major source of water vapor in the southern hemisphere. Detailed simulations of this process with a three-dimensional circulation model indicate that the summertime interhemispheric exchange (Hadley cell) is very much stronger than transport by eddies in other seasons. As a result, water ice would be distributed globally were it not for the buffering action of regolith soil adsorption which limits the net flux of water vapor off the north polar cap to amounts that are insignificant even on the scale of thousands of years. It has been suggested that the polar layered deposits are the result of exchange on these long time scales, driven by changes in Martian orbital parameters. We therefore are conducting simulations to test the effect of varied orbital parameters on the Martian water cycle. We find that when the perihelion summer pole is charged with a polar water ice cap, large quantities of water are quickly transfered to the aphelion summer pole, setting up an annual cycle that resembles the present one. Thus, the adsorptivity of the Martian regolith may be in the narrow range where it can limit net transport from the aphelion but not the perihelion pole. 相似文献
869.
Spaceflight and clinorotation cause cytoskeleton and mitochondria changes and increases in apoptosis in cultured cells. 总被引:7,自引:0,他引:7
The cytoskeleton is a complex network of fibers that is sensitive to environmental factors including microgravity and altered gravitational forces. Cellular functions such as transport of cell organelles depend on cytoskeletal integrity; regulation of cytoskeletal activity plays a role in cell maintenance, cell division, and apoptosis. Here we report cytoskeletal and mitochondria alterations in cultured human lymphocyte (Jurkat) cells after exposure to spaceflight and in insect cells of Drosophila melanogaster (Schneider S-1) after exposure to conditions created by clinostat rotation. Jurkat cells were flown on the space shuttle in Biorack cassettes while Schneider S-1 cells were exposed to altered gravity forces as produced by clinostat rotation. The effects of both treatments were similar in the different cell types. Fifty percent of cells displayed effects on the microtubule network in both cell lines. Under these experimental conditions mitochondria clustering and morphological alterations of mitochondrial cristae was observed to various degrees after 4 and 48 hours of culture. Jurkat cells underwent cell divisions during exposure to spaceflight but a large number of apoptotic cells was also observed. Similar results were obtained in Schneider S-1 cells cultured under clinostat rotation. Both cell lines displayed mitochondria abnormalities and mitochondria clustering toward one side of the cells which is interpreted to be the result of microtubule disruption and failure of mitochondria transport along microtubules. The number of mitochondria was increased in cells exposed to altered gravity while cristae morphology was severely affected indicating altered mitochondria function. These results show that spaceflight as well as altered gravity produced by clinostat rotation affects microtubule and mitochondria organization and results in increases in apoptosis. Grant numbers: NAG 10-0224, NAG2-985. 相似文献
870.
A.V. Agapitov O.K. CheremnykhA.S. Parnowski 《Advances in Space Research (includes Cospar's Information Bulletin, Space Research Today)》2008,41(10):1682-1687
We investigate the generation of ballooning perturbations in the inner magnetosphere of the Earth in the dipole model of the geomagnetic field taking into account ionospheric boundary conditions. The ionosphere is considered as a thin layer with finite conductivity. The eigenmode spectrum is discrete and consists of Alfvén, slow magnetosonic, flute and incompressible modes. Their interaction depends on ionospheric conductivity. The decay rate is small in noon and night sectors and large in dawn and dusk sectors. The lowest stability threshold α/γ ≈ 4.25 is determined by flute modes. 相似文献