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771.
N Desai M Durante Z W Lin F Cucinotta H Wu 《Advances in Space Research (includes Cospar's Information Bulletin, Space Research Today)》2005,35(2):236-242
We investigated the spatial distribution of the induction of the phosphorylated form of the histone protein H2AX (gamma-H2AX), known to be activated by DSBs. Following irradiation of human fibroblast cells with 600 MeV/nucleon silicon and 600 MeV/nucleon iron ions we observed the formation of gamma-H2AX aggregates in the shape of streaks stretching over several micrometers in an x/y plane. Polyethylene shielding was used to achieve a Bragg curve distribution with beam geometry parallel to the monolayer of cells. We present data that highlights the formation of immunofluorescent gamma-H2AX tracks showing the ion trajectories across the Bragg peak of irradiated human fibroblast cells. Qualitative analyses of these distributions indicated potentially increased clustering of DNA damage before the Bragg peak, enhanced gamma-H2AX distribution at the peak, and provided visual evidence of high-linear energy transfer particle traversal of cells beyond the Bragg peak in agreement with one-dimensional transport approximations. Spatial assessment of gamma-H2AX fluorescence may provide direct insights into DNA damage across the Bragg curve for high charge and energy ions including the biological consequences of shielding and possible contributors to bystander effects. 相似文献
772.
L.S. Novikov V.N. MileevK.K. Krupnikov A.A. MakletsovB.V. Marjin M.O. RjazantsevaV.V. Sinolits N.A. Vlasova 《Advances in Space Research (includes Cospar's Information Bulletin, Space Research Today)》2008
The results of magnetospheric plasma fluxes measurement in geosynchronous orbit are presented. The measurements were done onboard the geosynchronous Russian “Electro” spacecraft (SC) in 1995–1997 years. The diurnal variations of the plasma density and temperature were observed at various levels of geomagnetic activity. 相似文献
773.
The results of numerical simulation for the diffusion processes “powder gases-steel” occurring in the barrel of a quick-firing small-caliber gun are presented. 相似文献
774.
The possibility of using the statistics of recurrence time for extreme events is studied in this paper having in mind the
problems of control and prediction of failures in spacecraft operation. The information about failures onboard satellites
of various types presented by the US National Geophysical Data Center was analyzed. It was found that the probability density
of recurrence intervals followed a power law of the Pareto type with an index equal to 2.3. The obtained result is consistent
both with the theory of normal catastrophes and with the principle of self-organization of criticality for metastable active
heterogeneous environment. A practical consequence of the obtained result consists in the fact that predictions of these extreme
events should not rely on traditional models with the second-order Pearson statistics. To make predictions, the models are
necessary that take into account the power law distribution of recurrence intervals for failures on satellites. The failures
should be considered in these models as extreme events connected with manifestation of the space environment factors. 相似文献
775.
S. N. Walker M. A. Balikhin I. Bates R. Huff 《Advances in Space Research (includes Cospar's Information Bulletin, Space Research Today)》2002,30(12):2815-2820
High order spectral techniques are one of the most powerful tools for the identification of non-linear processes in space plasma turbulence. Without such tools it is impossible to determine, for example, the occurrence of non-linear interactions between spectral components. However, since the observations made by an instrument involve some internal processing, it is possible that non-linearities may arise from within the instrument itself rather than in the plasma. The possibility of such effects are investigated using data resulting from tests carried out using the Cluster Wideband electric field instrument. 相似文献
776.
777.
V N Sychev E Y Shepelev G I Meleshko T S Gurieva M A Levinskikh I G Podolsky O A Dadasheva V V Popov 《Advances in Space Research (includes Cospar's Information Bulletin, Space Research Today)》2001,27(9):1529-1534
Since 1990, the orbital complex MIR has witnessed several incubator experiments for determination of spaceflight effects on embryogenesis of Japanese quail. First viable chicks who had completed the whole embryological cycle in MIR microgravity hatched out in 1990; it became clear that newborns would not be able to adapt to microgravity unaided. There were 8 successful incubations of chicks in the period from 1990 to 1999. In 1995-1997 the MIR-NASA space science program united Russian and US investigators. As a result, experiments Greenhouse-1 and 2 were performed with an effort to grow super dwarf wheat from seed to seed, and experiment Greenhouse-3 aimed at receiving two successive generations of Brassica rapa. But results of these experiments could not be used for definitive conclusions concerning effects of spaceflight on plant ontogenesis and, therefore, experiments Greenhouse-4 and 5 were staged within the framework of the Russian national space program. The experiments finally yielded wheat seeds. Some of the seeds was left on the space station and, being planted, gave viable seedlings which, in their turn, produced the second crop of space seeds. 相似文献
778.
N F Mikhaylenko S K Sytnik E K Zolotareva 《Advances in Space Research (includes Cospar's Information Bulletin, Space Research Today)》2001,27(5):1007-1010
Photochemical characteristics and lipid composition of thylakoid membranes from 12 day-old pea leaves that were exposed to slow clino-rotation were examined and compared with a vertical control. Proton permeability of thylakoid membranes was estimated from light-induced proton uptake (delta H+) and post-illumination proton efflux in chloroplast suspensions. The delta pH magnitude was calculated from the level of light-induced quenching of 9-aminoacridine fluorescence. Proton permeability of thylakoid membranes increased during exposure to clino-rotation. When subsequently transferred to darkness, proton efflux increased almost 2-fold in clinorotated leaves. The results were compared with data on pigment and polar lipid composition of photosynthetic membranes in clino-rotated and control plants. It was concluded that both the increase of proton permeability and the decrease of polar lipid content in chloroplasts were induced by clino-rotation. 相似文献
779.
N. O. Weiss 《Space Science Reviews》2006,124(1-4):13-22
Sunspots are the most prominent magnetic features on the Sun but it is only within the last few years that the intricate structure of their magnetic fields has been resolved. In the penumbra the fields in bright and dark filaments differ in inclination by 30°. The field in the bright filaments is less inclined to the vertical, while the field in dark filaments becomes almost horizontal at the edge of the spot. Recent models suggest that this interlocking-comb structure is maintained through downward pumping of magnetic flux by small-scale granular convection, and that filamentation originates as a convective instability. Within the bright filaments convection patterns travel radially owing to the inclination of the field. A proper understanding of these processes requires new observations, from space and from the ground, coupled with large-scale numerical modelling. 相似文献
780.
菲利普斯曲线之中国验证——基于1985-2004年的数据分析 总被引:4,自引:0,他引:4
孙海军 《华北航天工业学院学报》2006,16(1):21-24
本文在介绍分析菲利普斯曲线三种形态及其政策含义的基础上,使用中国的相关数据对其进行验证。本文对我国菲利普斯曲线的三种形态分别进行绘制和分析。在简要回顾对曲线走势有重要影响的宏观经济政策之后,提出当前应当逐渐由扩张性财政政策向中性的财政政策转变。 相似文献