“阿里安”4整流罩分离特性的推算

“阿里安”运载火箭的箭体和/或有效载荷及被抛投的半整流罩之间必须避免发生任何碰撞.必须通过分析和试验来确定相应的最小间隙.在简单地介绍整流罩结构和有限元模型后,作了分离分析研究.研究重点放在几何非线性效应上.将现有研究试验数据与相应的分析推算进行了比较,从而可以对整流罩的有限元模型进行改进,以供未来研究之用.     

Influence of ionic inorganic solutes on self-assembly and polymerization processes related to early forms of life: implications for a prebiotic aqueous medium

A commonly accepted view is that life began in a marine environment, which would imply the presence of inorganic ions such as Na+, Cl-, Mg2+, Ca2+, and Fe2+. We have investigated two processes relevant to the origin of life--membrane self-assembly and RNA polymerization--and established that both are adversely affected by ionic solute concentrations much lower than those of contemporary oceans. In particular, monocarboxylic acid vesicles, which are plausible models of primitive membrane systems, are completely disrupted by low concentrations of divalent cations, such as magnesium and calcium, and by high sodium chloride concentrations as well. Similarly, a nonenzymatic, nontemplated polymerization of activated RNA monomers in ice/eutectic phases (in a solution of low initial ionic strength) yields oligomers with > 80% of the original monomers incorporated, but polymerization in initially higher ionic strength aqueous solutions is markedly inhibited. These observations suggest that cellular life may not have begun in a marine environment because the abundance of ionic inorganic solutes would have significantly inhibited the chemical and physical processes that lead to self-assembly of more complex molecular systems.     

美空军全球空运医疗后送系统及保障能力

美国空军的伤病员空运医疗后送系统,是目前世界上相对完善和先进的伤病员医疗后送组织系统,堪称全球性空运医疗后送系统.这套系统可在全球范围内组织实施大规模的空运医疗后送保障活动,具有较强的空运后送伤病员能力.系统的构成美国空军的全球空运医疗后送组织系统由战术空运医疗后送系统、战略空运医疗后送系统和国内空运医疗后送系统三部分组     

狮子王辛巴的荣耀

寒流袭击的那天,没有冬天的广州突然出奇的寒冷。面对中国百年不遇的寒冷天气,我选择了逃离。连续飞行了14小时,穿越了5个时区,我降落在南半球被阳光燃烧着的肯尼亚首都内罗毕(NAIROBI)。我和一个中国人以及两个法国人,带上本地的黑人司机、厨师和充足的食品、水以及扎营设备,开着那辆带天窗的专业狩猎远征(SAFARI)越野车,做一次彻底的狩猎远征。     

Survival of Bacillus pumilus spores for a prolonged period of time in real space conditions

To prevent forward contamination and maintain the scientific integrity of future life-detection missions, it is important to characterize and attempt to eliminate terrestrial microorganisms associated with exploratory spacecraft and landing vehicles. Among the organisms isolated from spacecraft-associated surfaces, spores of Bacillus pumilus SAFR-032 exhibited unusually high resistance to decontamination techniques such as UV radiation and peroxide treatment. Subsequently, B. pumilus SAFR-032 was flown to the International Space Station (ISS) and exposed to a variety of space conditions via the European Technology Exposure Facility (EuTEF). After 18 months of exposure in the EXPOSE facility of the European Space Agency (ESA) on EuTEF under dark space conditions, SAFR-032 spores showed 10-40% survivability, whereas a survival rate of 85-100% was observed when these spores were kept aboard the ISS under dark simulated martian atmospheric conditions. In contrast, when UV (>110?nm) was applied on SAFR-032 spores for the same time period and under the same conditions used in EXPOSE, a ～7-log reduction in viability was observed. A parallel experiment was conducted on Earth with identical samples under simulated space conditions. Spores exposed to ground simulations showed less of a reduction in viability when compared with the "real space" exposed spores (～3-log reduction in viability for "UV-Mars," and ～4-log reduction in viability for "UV-Space"). A comparative proteomics analysis indicated that proteins conferring resistant traits (superoxide dismutase) were present in higher concentration in space-exposed spores when compared to controls. Also, the first-generation cells and spores derived from space-exposed samples exhibited elevated UVC resistance when compared with their ground control counterparts. The data generated are important for calculating the probability and mechanisms of microbial survival in space conditions and assessing microbial contaminants as risks for forward contamination and in situ life detection.     

可变体机翼多物理场分布式光纤集成测试技术

介绍了可变体机翼技术和可变体机翼多物理场光纤集成测试技术的研究现状.     

Simulation considers the human factors

Human factors aspects of flight simulation design at McDonnell Douglas are considered. Modeling approaches are examined and testing with pilots and cockpits is described.     

伊朗 谜一样的国度

电视中,每天都有关于伊朗的报道,伴随美国要打击伊朗的叫嚣,让人有种大战迫在眉睫的紧张。我唯恐伊朗再不去,这个国家就会像伊拉克一样,彻底改变当今的面貌。于是在好友的帮助下,展开了这次向往已久的伊朗之行。     

Genesis and preservation of a uranium-rich paleozoic epithermal system with a surface expression (Northern Flinders Ranges, South Australia): radiogenic heat driving regional hydrothermal circulation over geological timescales

The surface expressions of hydrothermal systems are prime targets for astrobiological exploration, and fossil systems on Earth provide an analogue to guide this endeavor. The Paleozoic Mt. Gee-Mt. Painter system (MGPS) in the Northern Flinders Ranges of South Australia is exceptionally well preserved and displays both a subsurface quartz sinter (boiling horizon) and remnants of aerial sinter pools that lie in near-original position. The energy source for the MGPS is not related to volcanism but to radiogenic heat produced by U-Th-K-rich host rocks. This radiogenic heat source drove hydrothermal circulation over a long period of time (hundreds of millions of years, from Permian to present), with peaks in hydrothermal activity during periods of uplift and high water supply. This process is reflected by ongoing hot spring activity along a nearby fault. The exceptional preservation of the MGPS resulted from the lack of proximal volcanism, coupled with tectonics driven by an oscillating far-field stress that resulted in episodic basement uplift. Hydrothermal activity caused the remobilization of U and rare earth elements (REE) in host rocks into (sub)economic concentrations. Radiogenic-heat-driven systems are attractive analogues for environments that can sustain life over geological times; the MGPS preserves evidence of episodic fluid flow for the past ～300 million years. During periods of reduced hydrothermal activity (e.g., limited water supply, quiet tectonics), radiolytic H(2) production has the potential to support an ecosystem indefinitely. Remote exploration for deposits similar to those at the MGPS systems can be achieved by combining hyperspectral and gamma-ray spectroscopy.