Voluntary head stabilization in space during trunk movements in weightlessness

The ability to voluntarily stabilize the head in space during lateral rhythmic oscillations of the trunk has been investigated during parabolic flights. Five healthy young subjects, who gave informed consent, were examined. The movements were performed with eyes open or eyes closed, either during phases of microgravity or phases of normal gravity. The main result to emerge from this study is that the head may be stabilized in space about the roll axis under microgravity conditions with, as well as without vision, despite the reduction of the vestibular afferent and the muscle proprioceptive inputs. Moreover, the absence of head stabilization about the yaw axis confirms that the degrees of freedom of the neck can be independently controlled, as it was previously shown [1]. These results seem to indicate that voluntary head stabilization does not depend crucially upon static vestibular afferents. Head stabilization in space may be in fact organized on the basis of either dynamic vestibular afferents or a postural body scheme.     

Amino aciduria in weightlessness

Urinary excretion of amino acids by the 9 Skylab crewmen was studied as an indicator of the metabolic effects caused by exposure to the space flight environment. Intake was consistent in quality and quantity throughout the 28, 59 and 84-day flights for each of the crewmen and complete collections were accomplished. The results indicated an increased excretion in most amino acids during the first month of flight which remained elevated in the second and third months but to a lesser extent. Additional indications of change in muscle and skeletal metabolism were observed. These results point to the desirability of obtaining additional indices of alterations in protein synthetic processes in conjunction with future space flights.     

Did mineral surface chemistry and toxicity contribute to evolution of microbial extracellular polymeric substances?

Abstract Modern ecological niches are teeming with an astonishing diversity of microbial life in biofilms closely associated with mineral surfaces, which highlights the remarkable success of microorganisms in conquering the challenges and capitalizing on the benefits presented by the mineral-water interface. Biofilm formation capability likely evolved on early Earth because biofilms provide crucial cell survival functions. The potential toxicity of mineral surfaces toward cells and the complexities of the mineral-water-cell interface in determining the toxicity mechanisms, however, have not been fully appreciated. Here, we report a previously unrecognized role for extracellular polymeric substances (EPS), which form biofilms in shielding cells against the toxicity of mineral surfaces. Using colony plating and LIVE/DEAD staining methods in oxide suspensions versus oxide-free controls, we found greater viability of wild-type, EPS-producing strains of Pseudomonas aeruginosa PAO1 compared to their isogenic knockout mutant with defective biofilm-producing capacity. Oxide toxicity was specific to its surface charge and particle size. High resolution transmission electron microscopy (HRTEM) images and assays for highly reactive oxygen species (hROS) on mineral surfaces suggested that EPS shield via both physical and chemical mechanisms. Intriguingly, qualitative as well as quantitative measures of EPS production showed that toxic minerals induced EPS production in bacteria. By determining the specific toxicity mechanisms, we provide insight into the potential impact of mineral surfaces in promoting increased complexity of cell surfaces, including EPS and biofilm formation, on early Earth. Key Words: Mineral toxicity-Bacteria-EPS evolution-Biofilms-Cytotoxicity-Silica-Anatase-Alumina. Astrobiology 12, 785-798.     

Microgravity and space processes

The implications of the STS-107 tragedy on weightlessness research in the NASA program are reviewed.     

下一代航天器的多用途贮箱

单组元和双组元推进系统已确定用于下一代航天器的轨道转换与姿态控制上,包括应用于通讯卫星、地球资源卫星、维修及补给卫星、气象卫星和防御卫星。基于上述应用的多用途貯箱是一种改型维金轨道器(VO-75)的圆筒形容器,直径为91厘米并有半球形封头,它92能用于航天飞机又能用于一次使用的助推火箭。本聍箱备有各种被动式全金属推进剂管理装置,以满足各种不同任务对加速度、流量、压力值、增压形式和轨道飞行中的晃动控制所提出的各种各样的要求。对各种装置的工作情况均结合其通用性和局限性来予以说明。对容积、重量、排空效率、容积效率等貯箱系统参数和相对成本,本文亦作了简介。     

PILOT:一个智能化的分布式系统管理器

NASA约翰逊航天中心正在作一系列研究,探索提高当前和未来载人指控中心工作效率和实用性的途径。实时数据系统(RTDS)工程已研究了几种技术并用于指控中心环境。该环境是以工程工作站构成的多机种网络,该网中仿真的和实际的航天飞机任务现场数据作实时分配。该系统由一组复杂的交互进程组成,必须以最少的停顿时间提供多种服务。本文介绍一些能保证系统各功能高度可靠和高度可用的方法。包括一个进程可见性工具,一个本地工作站环境监视器,一个网络级通信工具和一个采用人工智能技术的全局进程。     

科罗廖夫研制了哪些导弹

人们常常把C.Ⅱ.科罗廖夫的名字与航天飞行、研究和开拓星际空间联系在一起,这当然是对的。然而,他也有过积极从事第一批军用火箭研制的时候。其中最著名的大概算是P—7了。正是它后来成为建造一系列航天火箭的基础。同时,P—7并非是科罗廖夫研制的第一枚军用火箭,而且也绝不是最后一枚。正因为如此,总设计师的这一活动领域虽被保密的帷幕遮盖着,仍引起读者极大关注。可以想象,他们是很想通过作者首次在公开出版物上引用的数字与事实,来仔细研究一下C.科罗廖夫试验设计局研制远程弹道式火箭的经历的。     

Positive psychological effects of space missions

Being in space is a powerful experience that can have an enduring, positive impact on the psychological well-being of astronauts and cosmonauts. We sought to examine the frequency, intensity and distribution of such salutogenic experiences among persons who have flown in space, using a questionnaire we developed based on the scientific literature and first person accounts. All participants reported positive effects of being in space, but the degree of change varied widely, and some experiences were particularly common. Three of our five predicted attitude-behavior relationships were supported by the data. Response patterns did not vary according to demographics or time in space. Cluster analysis yielded two groups of participants. One group was generally more reactive and also placed a higher priority on perceptions of space than did the other group. We conclude that positive experiences are common among space travelers and seem to cluster into meaningful patterns that may be consequential for Mars missions. We consider the possible selection, training, and monitoring issues raised by our findings.     

一种数控铷原子频率震荡器的开发

铷原子振荡器(R_bOS C_s)适用于众多系统。在大多数情况下,它被用作“独立频率参考源”,近年,由于“相互同步”要求的提出,使得它们变得更重要了。 作者已开发了一种数控铷原子振荡器(DCRO),它可使另一个频率源同步。特别需强调的是它具有良好线性的3×10~(-8)的宽频率范围和1×10~(-12)频率调节步距。 为了获得一个拥有良好间距的宽频率范围,一种合成器被开发出来,它具有可变频率分配器的数据被写在一个3Mbit ROM中,并可使用计算机进行计算。 在具有δ~(y(τ))=6×10-12/τ1/2的良好频率稳定度的同时,超过20年的长寿命和小型化也被实现,它可轻易的满足电信和广播系统的要求。     

屏蔽室用的新型铁氧体栅格状吸收体

1 引言 符合CISPR(国际无线电干扰特别委员会)标准的辐射发射测量一般在开阔的测试场内进行。但这种方法有几个主要的缺限,或是它需要一个RF透明的、大的防风雨的封闭罩,不然,测量受气候的不可预测因素影响。这一防风雨的密封罩本身可能会引起测试场的误差[1]。更