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911.
T.G. Guzik J.H. Adams Jr. H.S. Ahn G.L. Bashindzhagyan K.E. Batkov J. Chang M. Christl A.R. Fazely O. Ganel R.M. Gunashingha J. Isbert K.C. Kim E.N. Kouznetsov M.I. Panasyuk A.D. Panov W.K.H. Schmidt E.S. Seo N.V. Sokolskaya J.W. Watts J.P. Wefel J. Wu V.I. Zatsepin 《Advances in Space Research (includes Cospar's Information Bulletin, Space Research Today)》2008
The Advanced Thin Ionization Calorimeter (ATIC) experiment is designed to investigate the charge composition and energy spectra of primary cosmic rays over the energy range from about 1011 to 1014 eV during Long Duration Balloon (LDB) flights from McMurdo, Antarctica. Currently, analysis from the ATIC-1 test flight and ATIC-2 science flight is underway and preparation for a second science flight is in progress. Charge identification of the incident cosmic ray is accomplished, primarily, by a pixilated Silicon Matrix detector located at the very top of the instrument. While it has been shown that the Silicon Matrix detector provides good charge identification even in the presence of electromagnetic shower backscatter from the calorimeter, the detector only measures the charge once. In this paper, we examine use of the top scintillator hodoscope detector to provide a second measure of the cosmic ray charge and, thus, improve the ATIC charge identification. 相似文献
912.
文红武 《西安航空技术高等专科学校学报》2015,(1)
脉宽调制数字快速电磁阀作为重要的电液转换元件,在燃油控制系统的作用日益突出。针对断电常开型快速电磁阀的需求,开展断电常开型脉宽调制数字快速电磁阀的方案设计及仿真研究,并通过工程验证使该脉宽调制数字快速电磁阀的设计方案得到优化。 相似文献
913.
914.
915.
A Schatz R Reitstetter A Linke-Hommes W Briegleb K Slenzka H Rahmann 《Advances in Space Research (includes Cospar's Information Bulletin, Space Research Today)》1994,14(8):35-43
Application of the Gouy-Chapman-Debye-Hückel (GCDH) theory to a model membrane in contact with electrolytes of various concentrations and composition predict density variations within an interfacial layer. Assuming that on cellular dimensions hydrodynamics can be applied (the objections are briefly discussed) two types of gravity effects can be defined, 1. convection along the surface of vertically oriented membranes and 2. surface potential variations by layer deformations at horizontally oriented membranes. Both effects should affect transport across the layer to the membrane surface and across the membrane. According to the theoretical predictions first experiments with gramicidin channels incorporated into artificial phosphatidylserine bilayer membranes show a significant difference in single channel currents in vertical and horizontal membranes. The complexity of biological membrane functions requires investigation of isolated membrane surface reactions and transport systems to study the gravisensitivity for each process separately. 相似文献
916.
A R Kranz K E Gartenbach M W Zimmermann 《Advances in Space Research (includes Cospar's Information Bulletin, Space Research Today)》1994,14(10):383-388
The role of cosmic ionizing radiation, including heavy ions (HZE-particles) in the induction of mutations at the molecule-, chromosome-, genome- and cell-level is discussed on the basis of different DNA organization in a pro- and eukaryotically compartmented plant system (Arabidopsis thaliana (L.) Heynh.). Data recently obtained on the biological effects of ionizing radiation make it timely to discuss comparatively the evolutionary potentials of space radiation effects in the pro- and eukaryotic genomes (plasmon, plastidom, chondriom, and nucleom) during long duration exposure on space flights. 相似文献
917.
W Briegleb 《Advances in Space Research (includes Cospar's Information Bulletin, Space Research Today)》1984,4(12):5-7
This paper speculates about the interplay between adaptational modifications with mutation and selection. Gravity effects are supposed to be very well suited to prove the role of direct adaptations for phylogenic processes. The speculation is based on strong hints that the cell in general reacts to accelerations (besides other mechanical stimuli) in the order of 1g and near weightlessness. Several-generations experiments in space may contribute to solve this fundamental question of evolution. 相似文献
918.
G W Nace 《Advances in Space Research (includes Cospar's Information Bulletin, Space Research Today)》1983,3(9):159-168
Normally bilateralization takes place in the presence of the Earth's gravity which produces torque, shear, tension and compression acting upon the naked aggregates of cytoplasm in the zygote which is only stabilized by a weak cytoskeleton. In an initial examination of the effects of these quantities on development, an expression is derived to describe the tendency of torque to rotate the egg and reorganize its constituents. This expression yields the net torque resulting from buoyancy and gravity acting upon a dumbbell shaped cell with heavy and light masses at either end and "floating" in a medium. Using crude values for the variables, torques of 2.5 x l0(-13) to 8.5 x 10(-1) dyne-cm are found to act upon cells ranging from 6.4 micrometers to 31 mm (chicken egg). By way of camparison six microtubules can exert a torque of 5 x 10(-9) dyne-cm. (1) Gravity imparts torque to cells; (2) torque is reduced to zero as gravity approaches zero; and (3) torque is sensitive to cell size and particulate distribution. Cells must expend energy to maintain positional homeostasis against gravity. Although not previously recognized, Skylab 3 results support this hypothesis: tissue cultures used 58% more glucose on Earth than in space. The implications for developmental biology, physiology, genetics, and evolution are considered. At the cellular and tissue level the concept of "gravity receptors" may be unnecessary. 相似文献
919.
Gloria W. Heath 《Acta Astronautica》1994,32(12):845-853
The stepping stones are traced from the birth of the IAA Committee on Space Rescue to the present day, 25 years later. The scope of the symposium was extended, successively, from that of space rescue to safety and rescue, and from crew rescue and spacecraft retrieval following Earth-surface touchdown to worldwide distress and disaster response, with benchmarks made on bringing to fruition satellite-aided search and rescue responding to terrestrial distress (COSPAS/SARSAT) and to space applications for disaster response.
In later years, a symposium session addressing space activities' impact on environment was initiated, with a principal focus on man-made space debris.
In 1991, a subcommittee on quality and an Ad Hoc Expert Group on space debris were established.
Its twenty-fifth-year contributions and influence are evident in the committee's organizational involvement across the IAA/IAF/COSPAR sessions at the 1992 World Space Congress. 相似文献
920.
J E Nealy J W Wilson M A Shea D F Smart 《Advances in Space Research (includes Cospar's Information Bulletin, Space Research Today)》1994,14(10):655-660
We have developed a model and associated computational procedure for estimating energetic proton exposures during a major solar proton event that occur in combination with a large magnetic storm. Transmission functions for solar protons are computed using geomagnetic vertical cutoff data for quiescent and disturbed conditions. Predicted exposures in low altitude polar orbit are found to be orders of magnitude greater for severe magnetic storm conditions than are corresponding exposures in the absence of major disturbances. We examine the response scenario for the events of November 1960 as an example. 相似文献