Urodelean amphibians in studies on microgravity: effects upon organ and tissue regeneration.

Results obtained from nine experiments performed onboard Russian biosatellites have shown that microgravity promotes tissue regeneration in the newt, Pleurodeles waltl. The effect has been reproduced in all flights and on a clinostat as well for eye tissues (lens and retina), limbs and tail. The effect was demonstrated in 1.5- to 2-fold increase in cell proliferation in the early stages of regeneration in space flight. Animals "flown" intact and operated after flight regenerated faster than control ones and showed long-lasting micro-"g" effect. The most recent experiment flew aboard the Bion-11 biosatellite. This test was performed for study on microgravity effect on neural retina regeneration after optic nerve lesioning in the newt. Obtained results confirmed our previous information about intensification of regenerative processes in detached neural retina in urodela exposed to simulated weightlessness (Grigoryan et al., 1998). In particular, we found the increase and activation of cell populations participating in neural retina restoration and maintenance of retinal structure. Our findings suggest that promoting effect of microgravity upon regeneration could be influenced by several factors, largely influenced by a response of the whole organism to changed gravity vector. We hypothesized the synthesis of the specific range of stress proteins induced by micro-"g" and their regulative role in cell proliferation. Such a hypothesis for the existence of "altered gravity stress proteins" is discussed.     

Experimental and mathematical modeling of the consumer's influence on productivity of algae in a model aquatic ecosystem.

A "producer-consumer" (Chlorella vulgaris-Paramecium caudatum) closed aquatic system has been investigated experimentally and theoretically. It has been found that there is a direct relationship between the growth of the paramecia population and their release of ammonia nitrogen, which is the best form of nitrogen for Chlorella growth. The theoretical study of a model of a "producer-consumer" aquatic biotic cycle with spatially separated compartments has confirmed the contribution of paramecia to nitrogen cycling. It has been shown that an increase in the concentration of nitrogen released as metabolites of paramecia is accompanied by an increase in the productivity of microalgae.     

A new thermoluminescent dosimeter system for space research

A small, portable, vibration and shock resistant thermoluminescent dosimeter system was developed to measure cosmic radiation dose on board a spacecraft. The system consists of a small battery-operated reader and a special bulb dosimeter. Doses from 10 μGy up to 100 mGy can be measured. The electrical power consumption of the reader is about 5 W, its volume is about 1 dm³ and its mass is about 1 kg. Details are given for the construction and technical parameters of the dosimeter and reader.     

Observations of the aurora in the far ultraviolet from “Cosmos-900”

The results from observations of auroral emissions within the wavelength band 115–135 nm are presented. The experiment was carried out on board the satellite “Cosmos-900”, launched on March 30, 1977, to an almost circular polar orbit. We assume that the precipitating fluxes of protons and electrons were the sources of excitation, according to the theory.     

Observational constraints on dark matter in the universe

Application of the cosmic virial theorem to galaxy redshift surveys suggests an open universe - if the dark material is distributed in the same way as galaxies. Here we investigate four redshift surveys. We present new results on the amplitudes of the two- and three-point galaxy correlation functions and we estimate the relative peculiar velocities in the deep redshift survey of Kirshner and co-workers (1983). Next, we review evidence which suggests that dark material is clustered on scales comparable to the optical radii of galaxies. In particular, we use spectroscopic and photometric observations to set constraints on the mass distribution in elliptical galaxies.     

Diurnal variations of ion flux intensity on a synchronous orbit

The data from the synchronous-orbit satellites of the Gorizont series are used to study the dependences of the ion flux variation amplitudes in the synchronous altitude region (the diurnal behaviour) on particle energies and on the form and rigidity of the particle energy spectrum. The proton fluxes were measured in the energy range E 60–120 keV, and the [N,0]²⁺ and [C,N,0]⁴⁺ ion fluxes in the energy range E 60–70 keV/e.

The ratio of the diurnal variation amplitudes of the studied ions is shown to correspond to the similarity of their energy spectra in the E/Q representation. The magnetically-quiet time gradient of the distribution function F(μ,J,L) in the synchronous-orbit region is shown to be (∂F/∂L)=0 for the H⁺ and [N,0]²⁺ ions and (∂F/∂L) > 0 for the [C,N,0]⁴⁺ ions (at the values of μ corresponding to the examined energy ranges). During magnetically-disturbed periods the inner boundary of the (∂F/∂L)=0 region shifts to lower L and (∂ F/∂L) = O in the synchronous altitude region must be also for the [C,N,O]⁴⁺ ions.