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N. F. Blagoveshchenskaya T. D. Borisova O. V. Kolosov V. A. Kornienko 《Advances in Space Research (includes Cospar's Information Bulletin, Space Research Today)》1995,15(12):111-114
Results of experimental studies of the ionospheric effects produced by CRRES barium releases are considered. The experimental observations of HF spectral characteristics by Doppler method are made by a network of long distance radio paths intersecting the L-shell of releases. The time dependence of their occurrence relative to the moment of release and the character of changes of spectral parameters produces signal effects (SE) which may be classified as: the unique burst, the quasiperiodic group of bursts, the regular changes of spectral parameters and wave processes. Observed types of SE are analogous to those seen when the releases were produced at the heights from 140 to 160 km. The result of experimental observations testify that there are special geophysical phenomena produced by barium releases. 相似文献
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T.A. Borisova N.V. Krisanova 《Advances in Space Research (includes Cospar's Information Bulletin, Space Research Today)》2008
High-affinity Na+-dependent glutamate transporters of the plasma membrane mediate the glutamate uptake into neurons, and thus maintain low levels of extracellular glutamate in the synaptic cleft. The study focused on the release of glutamate by reversal of Na+-dependent glutamate transporters from rat brain nerve terminals (synaptosomes) under conditions of centrifuge-induced hypergravity. Flow cytometric analysis revealed similarity in the size and cytoplasmic granularity between synaptosomal preparations obtained from control and G-loaded animals (10 G, 1 h). The release of cytosolic l-[14C]glutamate from synaptosomes was evaluated using the protonophore FCCP, which dissipated synaptic vesicle proton gradient, thus synaptic vesicles were not able to keep glutamate inside and the latter enriched cytosol. FCCP per se induced the greater release of l-[14C]glutamate in hypergravity as compared to control (4.8 ± 1.0% and 8.0 ± 1.0% of total label). Exocytotic release of l-[14C]glutamate evoked by depolarization was reduced down to zero after FCCP application under both conditions studied. Depolarization stimulated release of cytosolic l-[14C]glutamate from synaptosomes preliminary treated with FCCP was considerably increased from 27.0 ± 2.2% of total label in control to 35.0 ± 2.3% in hypergravity. Non-transportable inhibitor of glutamate transporter dl-threo-β-benzyloxyaspartate was found to significantly inhibit high-KCl and FCCP-stimulated release of l-[14C]glutamate, confirming the release by reversal of glutamate transporters. The enhancement of transporter-mediated release of glutamate in hypergravity was found to result at least partially from the inhibition of the activity of Na/K-ATPase in the plasma membrane of synaptosomes. We suggested that hypergravity-induced alteration in transporter-mediated release of glutamate indicated hypoxic injury of neurons. 相似文献
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T Borisova N Krisanova N Himmelreich 《Advances in Space Research (includes Cospar's Information Bulletin, Space Research Today)》2004,33(8):1362-1367
The biochemical basis underlying the effects of altered gravity on the process of nervous signal transmission is not clear. We have investigated the effect of hypergravity stress (created by centrifugation of rats at l0 g for 1 h) on the basal and stimulated release of L-[14C]glutamate (a chemical transmitter of excitatory signals) from isolated rat brain nerve terminals (synaptosomes). It has been shown that the hypergravity stress exerted a different influence on the Ca(2+)-dependent and the Ca(2+)-independent component of neurotransmitter release. The Ca(2+)-dependent L-[14C]glutamate release evoked by potassium chloride was equal to 14.4 +/- 0.7% of total synaptosomal label for control animals and 6.2 +/- 1.9% for animals, exposed to hypergravity (P < or = 0.05) and was more than twice decreased as a result of the hypergravity stress. We observed no statistically significant difference in the Ca(2+)-independent component of L-[14C]glutamate release. For control group and animals exposed to the hypergravity stress it was equal to 7.7 +/- 2.8% and 12.9 +/- 2.0%, respectively. We have also investigated the effect of the hypergravity stress on the activity of high-affinity Na(+)-dependent glutamate transporters. Km and Vmax of L-[14C]glutamate uptake have been determined. The maximal velocity of glutamate uptake was decreased as a result of hypergravity loading, but no difference in the Km values between control rats and hypergravity exposed animals was observed. These findings indicate that hypergravity stress alters neurotransmitter reuptake and exocytotic neurotransmitter release processes. 相似文献
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O. V. Borisova 《Russian Aeronautics (Iz VUZ)》2010,53(3):345-348
The skin panels of riveted cylindrical sections of flight vehicles in shear are considered. The objective of the analysis
based on the finite element method is to verify the recommendations available for determining critical stresses of similar
structural elements and to obtain new results for practical calculations. 相似文献
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用于铝合金的集成计算材料工程是将微观(10-10~10-8m)、细观(10-8~10-4m)、介观(10-4~10-2m)和宏观(10-2~10 m)等多尺度计算模拟和关键实验集成到铝合金设计开发的全过程中,通过成分-工艺-结构-性能的集成化,把铝合金的研发由传统经验式提升到以组织演化及其与性能相关性为基础的科学设计上,从而大大加快其研发速度,降低研发成本。本文详细阐述了原子尺度模拟、相图计算、相场、元胞自动机和有限元等计算模拟方法及微结构表征和性能测定的实验方法,论述了其在铝合金研发中所发挥的具体作用。基于集成计算材料工程,提出了从用户需要、设计制备和工业生产3个层面研发铝合金的具体框架。通过2个应用实例,展示了集成计算材料工程在铝合金研发中的强大功能,这也为新型铝合金及其它新材料的设计和开发提供了新模式。 相似文献
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N. F. Blagoveshchenskaya T. D. Borisova A. S. Kalishin V. N. Kayatkin T. K. Yeoman I. Häggström 《Cosmic Research》2018,56(1):11-25
Using the results of coordinated experiments on the modification of the high-latitude ionosphere by powerful HF radio emission of the EISCAT/Heating facility, effects of the impact of powerful HF radio waves of the ordinary (O-mode) and extraordinary (Х-mode) polarization on the high-latitude ionospheric F region have been compared. During the experiments, a powerful HF radio wave was emitted in the magnetic zenith direction at frequencies within the 4.5–7.9 MHz range. The effective power of the emission was 150–650 MW. The behavior and characteristics of small-scale artificial ionospheric irregularities (SAIIs) during O- and X-heating at low and high frequencies are considered in detail. A principal difference has been found in the development of the Langmuir and ion–acoustic turbulence (intensified by the heating of the plasma and ion–acoustic lines in the spectrum of the EISCAT radar of incoherent scatter of radio waves) in the О- and Х-heating cycles after switching on the heating facility. It has been shown that, under the influence on the ionospheric plasma of a powerful HF radio wave of the Х-polarization, intense spectral components in the spectrum of the narrow-band artificial ionospheric radio emission (ARI) were registered at distances on the order of 1200 km from the heating facility. 相似文献
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为了研究水润滑高分子材料轴承的微观界面的流场特性,本文以单个微凹体中的流场作为研究对象,建立了单个微凹体流动模型。采用多松弛格子玻尔兹曼方法MRT-LBM (multi-relaxation time lattice Boltzmann method)对单个微凹体的流体流动问题进行数值模拟。研究了流场中速度的变化规律,以及流场中流线分布随雷诺数的变化规律。结果表明当雷诺数较低时,流场处于稳定性流动状态;当雷诺数达到一定程度时,流场处于周期流动状态;当雷诺数很高时,流场处于湍流运动状态。探究微观流场中复杂的变化规律,为研究水润滑高分子材料轴承的润滑和摩擦性能提供一些理论支撑。 相似文献
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针对车载捷联惯导系统(SINS),提出一种快速行进间粗对准方法。将捷联矩阵分解为3个矩阵相乘,利用GPS提供的载体在导航坐标系的速度和里程计提供的载体在载体坐标系的速度构建不共线向量,求解初始载体坐标系相对惯性坐标系的常值转换矩阵,进而求得初始姿态矩阵。该对准方法对载车的唯一要求是在对准过程中做一个转弯机动。与现有对准方法相比,该方法没有用到加速度计信息。仿真结果表明,该方法能在1 min之内完成粗对准,采用零偏为0.1(°)/h的低精度陀螺,对准误差小于0.3°。 相似文献
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