Quantitative electrocardiography during extended space flight

To assess the effects of prolonged space flight on the electrophysiological properties of the heart, vectorcardiograms (VCG) were obtained on the Skylab crews at regular intervals during flight and the pre- and postflight periods. The VCG signals were telemetered from Skylab and analyzed by digital computer. Conventional 12-lead electrocardiograms were derived from the VCG signals by a lead transformation program. Standardized exercise loads were incorporated into the experiment protocol to increase the sensitivity of the VCG for effects of deconditioning and to detect susceptibility for arrhythmias. In Skylab II, 24 preflight, 21 inflight, and 19 postflight experiments were analyzed. Statistically significant inflight changes observed in two or more crew members included: decreased resting heart rate, increased QRS duration, anterior shift QRS vector, increased QRS vector magnitude, anterior shift T vector, and increased T vector magnitude. One astronaut had occasional premature ventricular contractions (PVC) during the pre- and postflight phases. He had a single episode of multiple PVC's during heavy-load exercise testing in flight. A second astronaut had no arrhythmia during pre- or inflight testing. On postflight day 21 he had multiple PVC's and salvos of ectopic ventricular beats. He has had no recurrence of the arrhythmia. With the exception of the cardiac arrhythmias, no deleterious electrophysiological changes were observed during Skylab II.     

Blood volume regulating hormones response during two space related simulation protocols: four-week confinement and head-down bed-rest

The volume of regulating hormones (renin, aldosterone, arginine vasopressin and atrial natriuretic factor), electrolytes and creatinine concentrations, and blood pressure were measured in two different four-week experimental protocols: respectively -6 degrees head-down bed-rest (5 subjects) and confinement (6 subjects). We observed a significant increase (P < 0.01 at D2 vs D-5) of systolic blood pressure during confinement and a different level of response for some hormones, especially for arginine vasopressin (300% increase during confinement instead of 50% during bed-rest). The renin-angiotensin-aldosterone system was enhanced during confinement and head-down bed-rest. In both conditions, we obtained a similar pattern of response for blood volume regulating hormones. During confinement, two main factors were inactivity and stress activation of the sympathetic nervous system. In the bed-rest study the response is principally due to the fluid shift and blood volume adaptation but it is not possible to exclude the role of inactivity and stress.     

Changes in the loco-regional Cerebral Blood Flow (r.C.B.F.) during a simulation of weightlessness.

Experiments of prolonged bedrest in antiorthostatic position are conducted in order to simulated cardio-circulatory modifications observed in weightlessness. Until now, no studies of r.C.B.F. have been effected in these conditions. Six young, healthy volunteers (average age 23.8) were placed in strict bedrest and in antiorthostatic position -4 degrees for 7 days. The r.C.B.F. measurements were studied by 133Xe inhalation method using a 32 detectors system. Studies were made first in basal conditions, then between the 6th and 12th hr, and finally between the 72nd and the 78th hr after the beginning of the experiment. Three of the subjects received 0.450 mg of Clonidine daily during the experiment. In the subjects having taken no Clonidine, we observed a constant increase in r.C.B.F. (12, 17 and 16% respectively) in the first 12 hr; at the 72nd hour, all values had returned to basal state. This findings agrees with the well known notion of a rapid correction of hemodynamic disturbances observed in the first days of weightlessness. In the subjects treated with Clonidine, the increase of r.C.B.F. did not occur. Several mechanisms of action are possible; the Clonidine affecting either the heart by inhibiting volemic atrial receptors or the brain by direct vasoconstriction.     

Summary of medical investigations in the U.S.S.R. manned space missions.

The results of biomedical investigations carried out in the U.S.S.R. manned space missions are discussed. Their basic result is well-documented evidence that man can perform space flights of long duration. The investigations have demonstrated no direct correlation between inflight or postflight physiological reactions of crewmembers and flight duration. In all likelihood, this can be attributed to the fact that special exercises done inflight efficiently prevented adverse effects of weightlessness. However, human reactions to weightlessness need further study. They include negative calcium balance and anemia as well as vestibulo-autonomic disorders shown by crewmembers at early stages of weightlessness. Attention should be given to psychological, social-psychological and ethical problems that may also limit further increase in flight duration.     

System identification of dynamic closed-loop control of total peripheral resistance by arterial and cardiopulmonary baroreceptors.

Prolonged exposure to microgravity in space flight missions (days) impairs the mechanisms responsible for defense of arterial blood pressure (ABP) and cardiac output (CO) against orthostatic stress in the post-flight period. The mechanisms responsible for the observed orthostatic intolerance are not yet completely understood. Additionally, effective counter measures to attenuate this pathophysiological response are not available. The aim of this study was to investigate the ability of our proposed system identification method to predict closed-loop dynamic changes in TPR induced by changes in mean arterial pressure (MAP) and right atrial pressure (RAP). For this purpose we designed and employed a novel experimental animal model for the examination of arterial and cardiopulmonary baroreceptors in the dynamic closed-loop control of total peripheral resistance (TPR), and applied system identification to the analysis of beat-to-beat fluctuations in the measured signals. Grant numbers: NAG5-4989.     

Vestibular tests in the selection of cosmonauts.

Vestibulo-vegetative disorders in cosmonauts and astronauts occurring during space flight compel otolaryngologists to search for vestibular tests enabling a precise evaluation of the activity of the vestibular apparatus and showing disposition to motion sickness. Otoneurological investigation of Polish candidates for cosmonaut status consisted of the following vestibular tests: caloric, rotatory, optokinetic, swinging torsion, statokinesimetric and vestibulo-vegetative. The value of various vestibular tests for aviation and space medicine is presented in this paper, taking into account the results of investigations of the equilibrium system with the group of pilots selected for space flight as well as extensive experience with candidates for the air service and also trained pilots and patients. The relatively frequent lack of correlation between the results of the applied tests, which renders difficult the proper evaluation of the equilibrium system, is emphasized in the paper. Finally, the results of investigations of acute habituation of the vestibular apparatus are discussed.     

Role of interface deformations in Benard-Marangoni instability

This work is concerned with a linear analysis of natural thermoconvection in a two-layer system formed by a liquid surmounted by an upper immiscible gas layer (Bénard-Marangoni problem). Emphasis is put on the role of the air layer on the thermoconvective instability. It is shown that the motion inside the gas phase can be disregarded provided its thickness is smaller than the thickness of the liquid layer. The gas can then be modelled as a purely conductive medium. Another important problem discussed here is the role of surface deformations on the onset of convection. In that respect, the use of Boussinesq's approximation is discussed and its limits of validity are specified. The main results are the following. First, it is concluded that overstability cannot be observed in ordinary fluids under realistic experimental conditions. Besides, it is shown that, among the relatively larger number of parameters appearing in the problem, the viscosity is by far the most important. Moreover, new dimensionless numbers are introduced to better apprehend the physical context. The experimental conditions required to observe the surface zero-wave number instability are also determined, as well as the conditions under which gravity effects may be neglected on earth. Finally it is examined under which circumstances the interface can be considered as remaining flat.     

Impaired T-wave amplitude adaptation to heart-rate induced by cardiac deconditioning after 5-days of head-down bed-rest

The study of QT/RR relationship is important for the clinical evaluation of possible risk of acquired or congenital ventricular tachyarrhythmias. In the hypothesis that microgravity exposure could induce changes in the repolarization mechanisms, our aim was to test if a short 5-days strict 6° head-down bed-rest (HDBR) could induce alterations in the QT/RR relationship and spatial repolarization heterogeneity. Twenty-two healthy men (mean age 31±6) were enrolled as part of the European Space Agency HDBR studies. High fidelity (1000 Hz) 24 h Holter ECG (12-leads, Mortara Instrument) was acquired before (PRE), the last day of HDBR (HDT5), and four days after its conclusion (POST). The night period (23:00–06:30) was selected for analysis. X, Y, Z leads were derived and the vectorcardiogram computed. Selective beat averaging was used to obtain averages of P–QRS–T complexes preceded by the same RR (10 ms bin amplitude, in the range 900–1200 ms). For each averaged waveform (i.e., one for each bin), T-wave maximum amplitude (Tmax), T-wave area (Tarea), RTapex, RTend, ventricular gradient (VG) magnitude and spatial QRS-T angle were computed. Non-parametric Friedman test was applied. Compared to PRE, at HDT5 both RTapex and RTend resulted shortened (−4%), with a decrease in T-wave amplitude (−8%) and area (−13%). VG was diminished by 10%, and QRS-T angle increased by 14°. At POST, QT duration and area parameters, as well as QRS-T angle were restored while Tmax resulted larger than PRE (+5%) and VG was still decreased by 3%. Also, a marked loss in strength of the linear regression with RR was found at HDT5 in Tmax and Tarea, that could represent a new dynamic marker of increased risk for life-threatening arrhythmias. Despite the short-term HDBR, ventricular repolarization during the night period was affected. This should be taken into account in astronauts for risk assessment during space flight.     

Toward a new cosmic consciousness: Psychoeducational aspects of contact with extraterrestrial civilizations

This study presents a new approach to the concept of cosmic consciousness integrated in current neuroscience knowledge and discusses implications for the search for extraterrestrial intelligence. It also examines different aspects related to consciousness and how it may play a key role in the understanding of the search for extraterrestrial intelligence and life in the Universe and its implications. Subjects (n=116) were college students from Spain, the United States, and Italy. Subjects responded to a questionnaire comprising five different sections: (A) religious beliefs, (B) environment and general opinion, (C) astronomy, (D) contact, and (E) attention and perception. The results showed the importance of several modular aspects that affect Space awareness in humans. Preliminary results are discussed with regard to current neuroscience, factor analysis, and possible implications for the understanding of contact with extraterrestrial intelligence. The roles of education, new search strategies, and possible contact scenarios are also discussed.     

WL_Net在导弹飞行控制软件安全性分析中的应用

提出了应用工作流逻辑网(WL_Net)进行软件安全性分析的新方法。介绍了运用WL_Net对导弹飞行控制软件进行安全性分析的步骤并分析了其优缺点和未来的发展方向。首先,综合考虑可能引起危险和风险的条件和环境构建WL_Net结构模型;然后使用可达树或关联矩阵对模型的合理性以及危险或风险出现的可能性进行分析,以确定该飞行控制软件是否安全。WL_Net能较好的完成对系统的建模和对软件安全性的分析,从一定程度上解决模型可读性和网结构爆炸的问题。     

Reflections on human presence in space.

Humankind's exploration of Space has until now been understood as analogous to that of planet Earth: sending out crews to far-off, unknown lands in the hope of finding supplies of food, water or energy along with shelter and living-space. But Space is turning out to be much less hospitable than our earthly milieu in terms of resources as well as energy costs. It seems appropriate to ask what level of adaptation is needed for humans to travel and live in the cosmos, and to assess if the next logical step should necessarily be a programme of conquest analogous to that of the Moon--for example, towards Mars. Should we not rather be making more use of Earth's immediate neighbourhood, namely the sphere of a million of kilometres we call "Greater Earth"? In the same way, it is appropriate to ask questions about the conception of human beings which will from now on sustain the conquest of Space. The astronaut of the last forty years is the direct heir of the explorers of Ancient and Modern times; now, through the influence of science and technology, humanity has been put "into motion" not only geographically, but also in its most essential foundations: culture, psychology, philosophy. If the development of telepresence technology now gives us the ability to talk about a "Greater Human Being", it is chiefly through freedom of choice for oneself, for humanity and even for Earth.     

Novel orbits of Mercury,Venus and Mars enabled using low-thrust propulsion

Exploration of the inner planets of the Solar System is vital to significantly enhance the understanding of the formulation of the Earth and other planets. This paper therefore considers the development of novel orbits of Mars, Mercury and Venus to enhance the opportunities for remote sensing of these planets. Continuous acceleration is used to extend the critical inclination of highly elliptical orbits at each planet and is shown to require modest thrust magnitudes. This paper also presents the extension of existing sun-synchronous orbits around Mars. However, unlike Earth and Mars, natural sun-synchronous orbits do not exist at Mercury or Venus. This research therefore also uses continuous acceleration to enable circular and elliptical sun-synchronous orbits, by ensuring that the orbit's nodal precession rate matches the planets mean orbital rate around the Sun, such that the lighting along the ground-track remains approximately constant over the mission duration. This property is useful both in terms of spacecraft design, due to the constant thermal conditions, and for comparison of images. Considerably high thrust levels are however required to enable these orbits, which are prohibitively high for orbits with inclinations around 90°. These orbits therefore require some development in electric propulsion systems before becoming feasible.     

Effects of uncertainties and flexible dynamic contributions on the control of a spacecraft full-coupled model

One of the most important problems for performing a good design of the spacecraft attitude control law is connected to its robustness when some uncertainty parameters are present on the inertial and/or on the elastic characteristics of a satellite. These uncertainties are generally intrinsic on the modeling of complex structures and in the case of large flexible structures they can be also attributed to secondary effects associated to the elasticity. One of the most interesting issues in modeling large flexible space structures is associated to the evaluation of the inertia tensor which in general depends not only on the geometric ‘fixed’ characteristic of the satellite but also on its elastic displacements which of course in turn modify the ‘shape’ of the satellite. Usually these terms can be considered of a second order of magnitude if compared with the ones associated to the rigid part of a structure. However the increasing demand on the dimension of satellites due to the presence for instance of very large solar arrays (necessary to generate power) and/or large antennas has the necessity to investigate their effects on their global dynamic behavior in more details as a consequence. In the present paper a methodology based on classical Lagrangian approach coupled with a standard Finite Element tool has been used to derive the full dynamic equations of an orbiting flexible satellite under the actions of gravity, gravity gradient forces and attitude control. A particular attention has been paid to the study of the effects of flexibility on the inertial terms of the spacecraft which, as well known, influence its attitude dynamic behavior. Furthermore the effects of the attitude control authority and its robustness to the uncertainties on inertial and elastic parameters has been investigated and discussed.     

Spatio-Temporal Ontologies and Attention

ABSTRACT

This paper presents a new proposal for the design of spatio-temporal ontologies which has its origin in cognitively motivated spatial semantics. It is shown that selective attention not only plays a central role in the characterization of spatial relations but that the representation of attentional aspects also leads to the possibility of defining an ontological upper structure which systematically covers both the spatial and the temporal domain.     

绳系卫星系统交会对接的应用与设计

文章介绍了绳系系统交会对接这项新技术在空间中的应用。主要包括：空间站利用系绳与航天器交会对接,实现为空间站提供各种供给;利用绳系系统与空间碎片对接,可回收或转移空间碎片,保护空间环境;利用一级或多级的绳系系统组成轨道转移系统,实现向地球同步轨道或火星轨道上转移和运送有效载荷。文章还介绍了绳系交会对接系统的设计,包括系统的一般控制方法和算法以及系统的结构设计。随着各项相关技术的发展,绳系卫星系统交会对接将发挥更大作用。     

Spectral signatures of photosynthesis. I. Review of Earth organisms

Why do plants reflect in the green and have a "red edge" in the red, and should extrasolar photosynthesis be the same? We provide (1) a brief review of how photosynthesis works, (2) an overview of the diversity of photosynthetic organisms, their light harvesting systems, and environmental ranges, (3) a synthesis of photosynthetic surface spectral signatures, and (4) evolutionary rationales for photosynthetic surface reflectance spectra with regard to utilization of photon energy and the planetary light environment. We found the "near-infrared (NIR) end" of the red edge to trend from blue-shifted to reddest for (in order) snow algae, temperate algae, lichens, mosses, aquatic plants, and finally terrestrial vascular plants. The red edge is weak or sloping in lichens. Purple bacteria exhibit possibly a sloping edge in the NIR. More studies are needed on pigment-protein complexes, membrane composition, and measurements of bacteria before firm conclusions can be drawn about the role of the NIR reflectance. Pigment absorbance features are strongly correlated with features of atmospheric spectral transmittance: P680 in Photosystem II with the peak surface incident photon flux density at approximately 685 nm, just before an oxygen band at 687.5 nm; the NIR end of the red edge with water absorbance bands and the oxygen A-band at 761 nm; and bacteriochlorophyll reaction center wavelengths with local maxima in atmospheric and water transmittance spectra. Given the surface incident photon flux density spectrum and resonance transfer in light harvesting, we propose some rules with regard to where photosynthetic pigments will peak in absorbance: (1) the wavelength of peak incident photon flux; (2) the longest available wavelength for core antenna or reaction center pigments; and (3) the shortest wavelengths within an atmospheric window for accessory pigments. That plants absorb less green light may not be an inefficient legacy of evolutionary history, but may actually satisfy the above criteria.     

用于微振动测量的高精度加速度传感器标定方法

微振动试验中所用的加速度传感器简称高精度加速度传感器,其相比于常规加速度传感器测量量级很低,可以达到10-5g量级甚至更低,用常规的加速度动态标定技术无法实现该量级水平的标定,也无从验证其测量精度的准确性。针对高精度加速度传感器测试精度的标定难题,文章提出在气浮台上设置比对梁的方法,通过激光测振仪和高精度加速度传感器对同一测点进行测量,并将两者的测量结果进行比对分析,以标定高精度加速度传感器的低量级测试精度。同时设计试验对手头现有的微振动加速度传感器进行标定以验证该方法的有效性,试验结果表明:利用激光测振仪标定现有高精度加速度传感器得到的比对结果符合预期;高精度加速度传感器测得的时域波形及频域波形与激光测振仪测得的基本一致,比对偏差在10%左右,满足标定方法要求。     

数字处理技术在电子侦察中的应用

通过对信号进行侦察的数学模型和一种基于混沌序列的反侦察系统的介绍,讨论了在对抗与反对抗中取得信息优势的关键技术。指出了数字处理技术在电子侦察领域的重要作用及应用状况,并提出了一种新的反侦察技术的设想。     

Legal science as catalyzer of SETI science, engineering and operations

Law is the oldest social science; in this condition it has a protagonic role in the development of other sciences, engineering and operations, because it allows them to aim for the desired goal in order and in a frame of legal possibility.The search for extraterrestrial intelligence implies the will of establishing a further relation. Relationships imply law.The role of law is not only participative as in multidisciplinary programs, but also interdisciplinary in the sense of harmonizing the several legal frameworks of the diverse sciences.SETI protocols I and II show, since their first draft, the harmonizing role of law. They are appropriated guidelines for a code of ethics and a code of conduct.The refinement of the concepts must be continued to reach finally the legal principles that shall govern these activities. Principles must be established before the production of facts, because law as a science, does not conceive the lacunae. Moreover, space law has always anticipated the technical facts hierarchizing its scientific condition.     

Space, ethics and society. A CMES study

Ethical issues have for long been limited to the fields of medicine and biotechnology, whereas to-day such matters encompass a growing number of engineering activities. 21^st century citizens are more equiring about technoscientific claims and accomplishments. Has their impact on society and the ecological environment been measured and quantified? With all this accumulated knowledge and progress do they have the ability and means to resolve these self-created difficulties? Or will a totally new approach have to be sought? The debates include space activity not only because of the public funding needed but also because of the possible consequences on humans as well as the terrestrial, orbital or outer environment. Since the fall of 1998, CNES has undertaken the study of the role played by space activities in to-day's society and that of the future, seeking to clarify the objectives of the former with the expectations of the latter, and how they converge. The purpose of this study is to determine precisely the ethical responsibility of the space agencies and to pursue more sociological and philosophical research on the ethical scope of space activities.