A study of biohazard protection for farming modules of lunar base CELSS.

For the Closed Ecological Life Support System (CELSS) of a manned lunar base which is planned to be built on the moon early in the 21st century, several proposed programs exist to grow vegetables inside a farming module. At the 40th IAF (Malaga, 1989) the author et al presented a proposal for supplying food and nutrients to a crew of eight members, a basic concept which is based on growing four kinds of vegetables. This paper describes measures for biohazard protection in farming modules. In this study, biohazard protection means prevention of the dispersion of plant diseases to other plant species or other portions of farming beds.     

Delta-electron emission in fast heavy ion atom collisions.

Biological damages such as mutations, chromosomal aberrations etc. are a consequence of biochemical changes mostly in the DNA. With ionizing radiation, these chemical changes are due to primary ionization events and secondary ionization effects caused by the primarily produced electrons. Differences in the biological response of densely ionizing radiation, like heavy charged particles, in comparison to sparsely ionizing radiation, such as X- or gamma-rays, are mainly due to the differences in the production of the so called delta-electrons. Therefore, the emission process of electrons i.e. the cross section for the primary ionization event as well as the energy and angular distribution of the emitted electrons should be understood in detail. The delta-electron emission processes occuring in fast heavy ion atom collisions are explained qualitatively. The different spectral structures of electron emission arising from either the target or the projectile are explained in terms of simple models of the kinetics of momentum transfer induced by the COULOMB forces. In collisions of very heavy ions with matter, high nuclear COULOMB forces are created. These forces lead to a strong polarization of the electronic states of the participated electrons. The effects of this polarization are discussed.     

RBE for non-stochastic effects.

Evidence is reviewed concerning the variation of RBE values of high-LET radiations for non-stochastic effects, generally impairment of tissue integrity and function. The RBE values are dependent on the type of radiation, the type of tissue effect and the dose rate or fractionation schedule. RBE values depend strongly on the effect considered, with high values for late effects in lung, kidney and central nervous system. RBE values generally increase with decreasing dose rate or dose per fraction. Maximum values can be derived by extrapolation on the basis of a radiobiological model. These values are denoted RBEm to distinguish them from RBEM derived for stochastic effects, e.g. carcinogenesis. Values of RBEm are generally in the range of 2 to 10 and are considerably smaller by a factor of 2 to 5 than values of RBEM for various types of stochastic effects. RBE values for effects from actual exposures to mixtures of high-LET and low-LET radiations can be derived by considering the doses received and the tissue at risk. Applications of RBEm values will yield estimates of maximum values of equivalent doses and these should only be applied for planning medical interventions if the contribution from high-LET radiation is small. The selection of Q values for radiation protection is mostly based on RBE--values and the application of Q values in cases where non-stochastic effects are important might therefore result in an overestimate of the risks of exposure.     

Fertilization and development of eggs of the South African clawed toad, Xenopus laevis, on sounding rockets in space.

Egg rotation and centrifugation experiments strongly suggest a role for gravity in the determination of the spatial structure of amphibian embryos. Decisive experiments can only be made in Space. Eggs of Xenopus laevis, the South African clawed toad, were the first vertebrate eggs which were successfully fertilized on Sounding Rockets in Space. Unfixed, newly fertilized eggs survived reentry, and a reasonable number showed a seemingly normal gastrulation but died between gastrulation and neurulation. Only a few reached the larval stage, but these developed abnormally. In the future, we intend to test whether this abnormal morphogenesis is due to reentry perturbations, or due to a real microgravity effect, through perturbation of the reinitiation of meiosis and other processes, or started by later sperm penetration.     

Catalytic wet-oxidation of human wastes produced in space: the effects of temperature elevation.

The filtrate of non-catalytical wet-oxidation sewage sludge was wet-oxidized again at 290 degrees C and 300 degrees C with a Ru-Rh catalyst. At each temperature, repeated batch tests were carried out. Both oxidation and denitrification efficiency of organic matter in the raw material were studied. In the 16 times batch tests at 300 degrees C, high and stable oxidation occurred. 98.0% of organic carbon in the raw material was oxidized and 98.3% of organic nitrogen was denitrified. At 290 degrees C, though high and stable denitrification occurred, oxidation did not occur highly and stably. A catalytic wet-oxidation system studied at 300 degrees C will be useful as a waste management system for a human life support system, where almost all food is resupplied from the earth. This system can prevent organic waste accumulation in the life support system.     

Results from the Energetic Gamma-Ray Experiment Telescope (EGRET) on the Compton Observatory

The Energetic Gamma-Ray Experiment Telescope (EGRET) on the Compton Gamma Ray Observatory covers the high energy gamma ray energy range, approximately 30 MeV to 30 GeV, with a sensitivity considerably greater than earlier high energy gamma-ray satellites. Thus far, 4 pulsars have been detected and their properties measured, including in 3 cases the energy spectrum as a function of phase. The details of the galactic plane are being mapped and a spectra of the center region has been obtained in good agreement with that expected from cosmic ray interactions. The Magellanic clouds have been examined with the Large Magellanic Cloud having been detected at a level consistent with it having a cosmic ray density compatible with quasi-stable equilibrium. Sixteen Active Galactic Nuclei (AGN's) have been seen thus far with a high degree of certainty including 12 quasars and 4 BL Lac objects, but no Seyferts. Time variation has been detected in some of these AGN's.     

Office Information Systems Cost Justification

The purpose of this paper is to present a new methodology for the cost justification of office information systems in engineering environments [1]. The methodology is called the hedonic wage model. It is based on the fact that the allocation of labor resources in an organization tends to conform to certain logical economic criteria. These criteria, along with information on the costs of labor and on how workers spend their time, permit inferences about the organizational values of key activities. The value of an information system can be estimated based on its contribution to the key activities.