Readaptation of the vestibuloocular reflex to 1g-condition in immature lower vertebrates (Xenopus laevis) after micro- or hypergravity exposure

The effects of altered gravitational conditions (AGC) on the development of the static vestibulo-ocular reflex (VOR) and readaptation to 1g were investigated in the amphibian Xenopus laevis. Tadpoles were exposed to microgravity (μg) during the German Space Mission D-2 for 10 days, using the STATEX closed survival system, or to 3g for 9 days during earth-bound experiments. At the beginning of AGC, the tadpoles had not yet developed the static VOR.

The main results were: (i) Tadpoles with ug- or 3g-experience had a lower gain of the static VOR than the 1g-controls during the 2nd and 5th post-AGC days, (ii) Readaptation to response levels of 1g-reared controls usually occurred during the following weeks, except in slowly developing tadpoles with 3g-experience. Readaptation was less pronounced if, during the acute VOR test, tadpoles were rolled from the inclined to the normal posture than in the opposite test situation.

It is postulated that (i) gravity is necessarily involved in the development of the static VOR, but only during a period including the time before onset of the first behavioural response; and (ii) readaptation which is superimposed by the processes of VOR development depends on many factors including the velocity of development, the actual excitation level of the vestibular systems and the neuroplastic properties of its specific pathways.     

Cardiac and vascular adaptation to 0g with and without thigh cuffs (Antares 14 and Altair 21 day Mir spaceflights)

Cardiovascular Actaptation was evaluated on 2 astronauts: one wearing thigh cuffs from flight day 1 to 8 (14d flight), the second without cuffs (21d flight). Ultrasound investigations were performed at rest and during LBNP. Results: Without thigh cuffs the cardiovascular Actaptation consists in (1) the development of a hypovolemia with an increase of the heart rate and the cardiac output, (2) the decrease of the vascular tone in the deep (mesenteric and splanchnic) and peripheral (Lower limbs) vascular areas. The use of thigh cuffs maintains the volemia and the cardiac output at the preflight level (without heart rate increase) and prevents the loss of vascular tone in the deep and peripheral areas. Moreover the adaptative process changes since the cuffs are removed and even the volemia seems to be unaffected at this stage the vascular tone decreases to a comparable extend as during the flight without cuffs. Nevertheless during the flight without cuffs or 3 days after removing the cuffs hemodynamic signs of decreased orthostatic tolerance are present during the inflight and the 3 days post flight LBNP. Presently the possible contribution of the thigh cuffs to the reduction of the vascular deconditioning has not been tested yet.     

The second generation of the incubator hardware for studying avian embryogenesis under microgravity conditions

This paper describes a technical device, INCUBATOR 1M, which enables incubation of Japanese quail eggs aboard the piloted orbital station.     

飞行模拟摄象装置中解决景深问题的新方法

在飞行模拟目视系统中,象是由闭路电视的光学探头由地景模型摄取的,对横过整个象区的模型表面成象,特别是当探头入瞳非常接近模型时的成象是一个重要的问题。当我们试图改善闭路电视摄象机的鉴别率和减小地景模型的比例时,这个问题就更加大了,使得在探头光学系统内部移动和倾斜透镜的普通技术对某些重要的探头系统不足以解决问题。对于大范围的物体共轭距离,探头系统光学象差的校正是一个密切相关的问题。对于标准的电视系统和激光电视系统中的这些问题都作了评论。叙述了一种新型的倾斜透镜系统。     

飞行模拟的虚象显示

利用简单的未经校正的塑料透镜给出飞行模拟器中飞行景象的虚象。虚象显示给模拟器驾驶员以真实的印象,因为象似乎离开模拟器一个实在的距离。好多飞行员在飞行模拟器中作了着陆和起飞试验,以客观地评价虚象显示。这种显示包括斯密特彩色投影器,后投影屏和一个大直径长焦距的平凸塑料透镜。还评述了另一种利用一个彩色电视监视器和两个平凸塑料透镜的虚象显示,但没有正式飞行员的评论。对各种透镜参数进行了研究以决定它们对飞行景象的影响。结论是:在某些条件下,简单的透镜是可以使用的,以利用斯密特投影系统或电视监视器得到有用的飞行景象的虚象模拟。     

GE90的飞行试验验证了其使用性

GE公司已经完成了推力为377千牛的GE90发动机的使用性和系统验证飞行试验,证明这种发动机可以由波音公司开始进行获准180分钟ETOPS的飞行试验.GE90的飞行试验是在1993年12月到今年3月17日分两个阶段进行的.试验时此发动机装在GE公司的波音747空中试车台2号位上.这是一架曾经由泛美航空公司用过的波音747-100飞机,已经过大量改装.     

非地球同步轨道的应用潜力

最近的一项研究详细论述了在通信业务高峰期,利用非地球同步轨道卫星通信系统所具有的巨大优势。     

Invariant and energy analysis of an axially retracting beam

The mechanism of a retracting cantilevered beam has been investigated by the invariant and energy-based analysis. The time-varying parameter partial differential equation governing the transverse vibrations of a beam with retracting motion is derived based on the momentum theorem. The assumed-mode method is used to truncate the governing partial differential equation into a set of ordinary differential equations (ODEs) with time-dependent coefficients. It is found that if the order of truncation is not less than the order of the initial conditions, the assumed-mode method can yield accurate results. The energy transfers among assumed modes are discussed during retrac-tion. The total energy varying with time has been investigated by numerical and analytical methods, and the results have good agreement with each other. For the transverse vibrations of the axially retracting beam, the adiabatic invariant is derived by both the averaging method and the Bessel function method.     

用航空遥感器对海岸带海洋水色的分析

本文介绍了一种利用航空遥感器分析海岸带海洋水色的方法,这种方法已应用于亚得利亚海北部试验区,在不同高度上所获得的多光谱数据中。从海洋水色辐射计(工作谱段与海岸带彩色扫描仪相同)和六通道辐射计(工作在叶绿素自然荧光的光谱区域)所获得的数据,已用水色遥感辐射过程的模型,对大气和海面的影响进行了修正。遥感得到的水辐射光谱以及叶绿素和沉积物浓度经大气和海面影响修正之后的数据,证实了这种方法对悬浮或溶解于海水中的物质具有定量分析的能力。     

弹上测量仪器用的编码器

本文介绍的PCM—480编码器是高可靠的器件,平均无故障时间达48000小时。它包含串行和并行计算机接口,主/从能力,频率计数器、数据块,两个帧格式、两种码速率,加速度计信号调节单元等。文中讨论了系统结构、计算机接口、相位锁决环、信号调节器等部件。由于使用了CMOS电路的新技术,电源的功耗己减至最低限度。其结构紧凑,能更有效地利用空间。