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Critical need for a swingby return option for early manned Mars missions.
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Modelling of cosmic-ray muon exposure in building's interior.
Physical parameters on the exposure indoors from cosmic ray muons were determined in order to undertake computer simulations. The hitherto known information was compiled, and the unknowns were newly calculated. Assumptions and approximations required in making a practical model were also described. The stopping power and the range of muons in a normal concrete as well as the air were calculated for the energy up to hundreds GeV. The consistency of those results with ready-made tables was found satisfactory although the comparisons were available only in the low energy tail. The scattering effect of cosmic ray muons in building's interior was examined numerically through very simple model calculations. It was revealed that the overall scattering effect would be ignored unless very small variations are wanted. The iron fraction in a reinforced concrete as well as the density of the concrete was also shown to be an ineffective factor.
Calculation on cosmic-ray muon exposure rate in non-walled concrete buildings.
Computer simulations on the exposure indoors from cosmic ray muons were practiced in the framework of non-scattering and non-cascade assumptions. The model buildings were two-dimensional, rectangular, and were made of a normal concrete. A stratified structure was assumed in each building, where no mezzanine was considered. Walls were not taken into account yet. The distributions of the exposure rates in 26-story buildings were illustrated in contour maps for various sets of parameters. All of them gave basically archlike patterns. Analyses of the results showed that the exposure rate is affected most largely by the floor board thickness. The ceiling height would be an insignificant factor for short buildings. The min/max ratio of the muon exposure rate in a moderate size building was estimated to be more than 0.7.
[Medical physiological problems caused by supersonic transport planes].
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[Multiplication of Paramecium aurelis on board the orbital station Saliout-6 (Cytose experiment)].
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Heavy cosmic-ray exposure of Apollo astronauts.
A comprehensive study of the heavy-particle cosmic-ray exposure received by the individual astronauts during the nine lunar Apollo missions reveals a significant variation in the exposure as a function of shielding and the phase of the solar cycle. The data are useful in planning for future long-range missions and in estimating the expected biological damage.
Workshop summary. Biomedical and Space-Related Research with Heavy Ions at the BEVALAC.
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Changes observed in lymphocyte behavior during gravitational unloading.
The effect of microgravity has been extensively studied on human lymphocytes in several space missions. A clear distinction must be made between two kinds of experiments: (i) with cells purified from the peripheral blood of test subjects before flight and then exposed inflight to mitogens and other activators (these are called in vitro experiments), and (ii) with lymphocytes from crewmembers of space missions exposed to mitogens prior to and after flight (ex vivo experiments). The first approach can be considered as basic research in cell biology in space; the second contributes to identifying the effects of the stress of spaceflight on the immune response of astronauts. The results from in vitro experiments have clearly shown that lymphocyte activation is nearly totally depressed in microgravity. This activation depression is confirmed by investigations on Earth in the fast rotating clinostat. Conversely, activation is increased when lymphocytes are cultured at 10 g in a centrifuge. In microgravity cell adhesion may be reduced, thus partly accounting for the decreased cell activation. The results of the experiments conducted at 10 g are due to a simultaneous activation of T- and B-lymphocytes by concanavalin A. The reduced activation observed in lymphocytes from crewmembers of space missions can be ascribed to both the physical and psychological stress of spaceflight. This observation was confirmed by investigations on subjects undergoing stress on Earth.
From gravity and the organism to gravity and the cell.
This workshop on Gravity and the Cell was modeled on a 1968 conference on Gravity and the Organism. Each conference tried to identify the most salient scientific questions about how gravity is important to living systems. In the roughly two decades between the conferences there have been impressive advances in experimental methods, but the major scientific questions that have driven their applications to problems of gravitational biology, i.e., our broad research goals, remain much the same. In the case of plant research, improvements and extensions of biochemical techniques for investigating the ways organisms use environmental (g-force) information in salubrious ways has kept pace with progress in plant biochemistry. We now know much more about the roles of organic and inorganic substances that plants employ for information transfer and growth regulation and about the avenues and mechanisms for transport of those key substances within organisms. We have seen the acceptance of a "local control" concept that regulation of g-responses depends critically on plasmodesmata and gap junctions which allow plants and animals to throttle the transport of growth regulators across tissue boundaries often, especially in the case of plants, far removed from the morphological regions of concentration of statocytes that were once thought to be the exclusive bioaccelerometers used by plants. NASA's sponsorship of ground-based research in gravitational biology has served as important underpinning for orbital flight programs in space biology. The currently most noteworthy research area of ignorance is the mechanism by which the physical event of g-force susception becomes the biological process of g-force perception. Only rarely has it been possible to perform a definitive test of a theory of mechanism of gravity perception. Therefore, experimental research efforts in gravitational physiology still are essentially dependent on exploratory studies for which stimulus/response experiments require experimental manipulation of test subjects' g-force environment. Many research efforts have focused narrowly on contrasting the responses of test subjects to only two gravitational environments, 1 g versus real or simulated zero g. Much less effort has been devoted to studies at other g levels. For experiments in gravitational physiology three rotating machines have made, and no doubt will continue to make, important contributions: the centrifuge, the clinostat, and, most of all, the orbiting space vehicle. Some research trends, viewpoints, and shifts of emphasis are discussed.
Radiosensitivity parameters for lethal mutagenesis in Caenorhabditis elegans.
For the first time track structure theory has been applied to radiobiological effects in a living organism. Data for lethal mutagenesis in Caenorhabditis elegans, obtained after irradiation with nine different types of ions of atomic number 1-57 and gamma rays have yielded radiosensitivity parameters (E0, sigma 0, kappa, m = 68 Gy, 2.5 x 10(-9) cm2, 750, 2) comparable with those found for the transformation of C3HT10 1/2 cells (180 Gy, 1.15 x 10(-10) cm2, 750, 2) but remote from those (E0 and sigma 0 = approximately 2 Gy, approximately 5 x 10(-7) cm2) for mammalian cell survival.
Making a home in space.
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Transport of cosmic ray nuclei in various materials.
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Recent approaches in the analysis of weightlessness effects on arthropod development.
The concept of Biological Development refers to the extremely complex process by which every biological organism reproduces starting from a huge single cell, the fertilized egg. It includes all aspects of cellular and intercellular structure and function. In spite of many recent advances, especially at the molecular and genetical level, we are still far from fully understanding the details and mechanisms at work in developmental systems. It is even unclear what physical mechanisms are used by the different molecular components resulting in the emergence of these higher levels of organization. Newman and Comper, have extensively discussed the "generic" physical forces potentially involved in pattern formation, arguing that among others, gravitational effects could be involved in the production of cytoplasmic, tissue and extracellular matrix components rearrangements playing a role in morphogenesis. Although plagued with the problem of being a very weak force, specially at the tiny dimensions of cells, gravity is one of the "generic" physical forces that have been continuously operating on biological organisms during evolution. Few scientists would argue against the idea that at least in the early times of evolution, gravity could have been involved in shaping the spatial inhomogeneities behind the initial phases of development.
Methods of galactic heavy ion transport.
Two methods of calculating the transition of galactic heavy ions in the Earth's atmosphere are compared with respect to accuracy, generality, and computer efficiency. The most general method is shown to have the highest accuracy and is a simple numerical procedure.
Energy-dependent parameterization of heavy-ion absorption cross sections.
An energy-dependent parameterization of the total absorption (reaction) cross sections for heavy ion (Z > or = 2) collisions at energies above 25 MeV per nucleon is presented. The formula will be especially useful in heavy-ion transport applications.
Galactic HZE propagation through the Earth's atmosphere.
A comprehensive physical model for galactic heavy ion propagation is presented. The nuclear fragmentation model is a simplified physical model but contains the major processes of importance to galactic ions. Comparison is made to measurements of atmospheric ion fluence and the limitations of these comparisons are discussed.
Physical, chemical, biochemical and biological techniques and processes. Proceedings of the F2.2, F2.3, F2.5, F4.3, F4.4, F4.9, F4.10 and F3.5 Meetings of COSPAR Scientific Commission F which were held during the Thirtieth COSPAR Scientific Assembly, Hamburg, Germany, 11-21 July 1994.
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