Renal excretion of water in men under hypokinesia and physical exercise with fluid and salt supplementation

It has been suggested that under hypokinesia (reduced number of steps/day) and intensive physical exercise, the intensification of fluid excretion in men is apparently caused as a result of the inability of the body to retain optimum amounts of water. Thus, to evaluate this hypothesis, studies were performed with the use of fluid and sodium chloride (NaCl) supplements on 12 highly trained physically healthy male volunteers aged 19-24 years under 364 days of hypokinesis (HK) and a set of intensive physical exercises (PE). They were divided into two groups with 6 volunteers per group. The first group of subjects were submitted to HK and took daily fluid and salt supplements in very small doses and the second group of volunteers were subjected to intensive PE and fluid-salt supplements. For the simulation of the hypokinetic effect, both groups of subjects were kept under an average of 4000 steps/day. During the prehypokinetic period of 60 days and under the hypokinetic period of 364 days water consumed and eliminated in urine by the men, water content in blood, plasma volume, rate of glomerular filtration, renal blood flow, osmotic concentration of urine and blood were measured. Under HK, the rate of renal excretion of water increased considerably in both groups. The additional fluid and salt intake failed to normalize water balance adequately under HK and PE. It was concluded that negative water balance evidently resulted not from shortage of water in the diet but from the inability of the body to retain optimum amounts of fluid under HK and a set of intensive PEs.     

Product Device Analysis for Radar Applications

By applying the theory of two-dimensional Fourier transforms to the response of a product device, results are developed that may be applied to tracking radar range gates, phase detectors, and angle-error detectors. These responses are general in that noises that are present can be nonstationary with arbitrary power spectrum while the radar signal, a pulse stream, can have any envelope shape.     

Instrumentation and data systems for high-time resolution study of space plasma shocks

This paper deals with the principal methods of achieving high-time resolution measurements for the study of fine structure of shocks and other discontinuities in space plasmas. In the measurements of ion energy spectra, we have obtained the time resolution about 1s.In the Soviet-Czechoslovak INTERSHOCK project we will obtain temporal resolution better than 0.1s in the measurement of the main plasma parameters. This will be obtained with the multichannel energy spectrometer and the on-board data acquisition and processing system triggered by the shock signature. This system controls the data sampling rate from some scientific instruments and switches on a high-sampling rate near the shock. The method implies detecting a shock by means of on-board processing of magnetic field and plasma parameters. The algorithm for this detection uses both parameters separately as well as in combinations.     

Magnetic field experiment for Voyagers 1 and 2

The magnetic field experiment to be carried on the Voyager 1 and 2 missions consists of dual low field (LFM) and high field magnetometer (HFM) systems. The dual systems provide greater reliability and, in the case of the LFM's, permit the separation of spacecraft magnetic fields from the ambient fields. Additional reliability is achieved through electronics redundancy. The wide dynamic ranges of ± 0.5 G for the LFM's and ± 20 G for the HFM's, low quantization uncertainty of ± 0.002 ( = 10^–5 G) in the most sensitive (± 8 ) LFM range, low sensor RMS noise level of 0.006 , and use of data compaction schemes to optimize the experiment information rate all combine to permit the study of a broad spectrum of phenomena during the mission. Objectives include the study of planetary fields at Jupiter, Saturn, and possibly Uranus; satellites of these planets; solar wind and satellite interactions with the planetary fields; and the large-scale structure and microscale characteristics of the interplanetary magnetic, field. The interstellar field may also be measured.     

Optimum Design of Single Channel per Carrier Satellite Systems

Optimization of available satellite power and transponder bandwidth is utilized to minimize the Earth station G/T in satellite channel per carrier (SCPC) systems. The corresponding optimum transponder output backoff is obtained. Applications in system design are given. In a previous paper [1] the channel capacity of a satellite transponder handling single channel per carrier (SCPC) transmission was derived. The link carrier-to-noise (C/N) ratio was maximized over the output backoff and the maximum bandwidth available was determined. Given the bandwidth per channel for each carrier, the channel capacity was obtained. The objective of the present investigation is to derive the minimum G/T of the Earth station in SCPC systems by optimum utilization of available satellite power and transponder bandwidth. Applications in system design are discussed.     

Radar Calibration Test Satellite

A satellite has been designed for application to radar calibration. Electromagnetic and mechanical characteristics of the satellite and their influence on the selection of shape and other parameters are discussed. Theoretical and experimental scattering data are included.     

VLF Multirange Navigation Errors

The fix error, for long-distance XIF navigation systems in which the distances to two or three ground-based stations are determined, is a function of the "angles of cut" of the lines of position, the standard deviation of the errors in determination of the distances (ranges) to the stations, and the degree of correlation of these distance determinations. An analysis is made of the errors which occur in a range determination. n. Estimates, applicable when comparing constant-error contours (isograms), are given. The equations for the constant-error contours are derived (based on a spherical earth) as a function of baseline length (and orientation where three stations are used) and the angles of cut of the lines of position. n. Various error isograms were computed and plotted through the use of a digital computer. A number of examples are presented. A method for determining the area covered acceptably by two stations is given and three-station coverage characteristics are discussed.     

Population dynamics of an algal-bacterial cenosis in closed ecological system.

The paper deals with microalgae-bacteria interrelationships in the "autotroph-heterotroph" aquatic biotic cycle. Explanations of why and how algal-bacterial ecosystems are formed still remain controversial. The paper presents results of experimental and theoretical investigations of the functioning of the algal-bacterial cenosis (the microalga Chlorella vulgaris and concomitant microflora). The Chlorella microbial community is dominated by representatives of the genus Pseudomonas. Experiments with non-sterile batch cultures of Chlorella on Tamiya medium showed that the biomass of microorganisms increases simultaneously with the increase in microalgal biomass. The microflora of Chlorella can grow on organic substances released by photosynthesizing Chlorella. Microorganisms can also use dying Chlorella cells, i.e. form a "producer-reducer" biocycle. To get a better insight into the cenosis-forming role of microalgae, a mathematical model of the "autotroph-heterotroph" aquatic biotic cycle has been constructed, taking into account the utilization of Chlorella photosynthates and dead cells by microorganisms and the contribution of the components to the nitrogen cycle. A theoretical study showed that the biomass of concomitant bacteria grown on glucose and detritus is larger than the biomass of bacteria utilizing only microalgal photosynthates, which agrees well with the experimental data.     

Cell-to-cell interactions in changed gravity: ground-based and flight experiments

Cell-to-cell interactions play an important role in all physiological processes and are mediated by humoral and mechanical factors. Mechanosensitive cells (e.g., osteocytes, chondrocytes, and fibroblasts) can be studied ex vivo to understand the effects of an altered gravity environment. In particular, cultured endothelial cells (EC) are very sensitive to a broad spectrum of mechanical and biochemical stimuli. Earlier, we demonstrated that clinorotation leads to cytoskeletal remodeling in cultured ECs. Long-term gravity vector changes also modulate the expression of surface adhesion molecules (ICAM-1, E-selectin, VCAM-1) on cultured ECs. To study the interactions of geterological cells, we cocultured endothelial monolayers and human lymphocytes, immune cells and myeloleucemic (K-560) cells. It was found that, although clinorotation did not alter the basal adhesion level of non-activated immune cells on endothelial monolayers, the adhesion of PMA-activated lymphocytes was increased. During flight experiments onboard the Russian segment of the International Space Station, we measured the cytotoxic activity of natural killer (NK) cells incubated with labeled target cells. It was found that immune cells in microgravity retained their ability to contact, recognize, and destroy oncogenic cells in vitro. Together, our data concerning the effects of simulated and real microgravity suggest that, despite changes in the cytoskeleton, cell motility, and expression of adhesion molecules, cell-cell interactions are not compromised, thus preserving the critical physiological functions of immune and endothelial cells.     

The Accretion, Composition and Early Differentiation of Mars

The early development of Mars is of enormous interest, not just in its own right, but also because it provides unique insights into the earliest history of the Earth, a planet whose origins have been all but obliterated. Mars is not as depleted in moderately volatile elements as are other terrestrial planets. Judging by the data for Martian meteorites it has Rb/Sr 0.07 and K/U 19,000, both of which are roughly twice as high as the values for the Earth. The mantle of Mars is also twice as rich in Fe as the mantle of the Earth, the Martian core being small (20% by mass). This is thought to be because conditions were more oxidizing during core formation. For the same reason a number of elements that are moderately siderophile on Earth such as P, Mn, Cr and W, are more lithophile on Mars. The very different apparent behavior of high field strength (HFS) elements in Martian magmas compared to terrestrial basalts and eucrites may be related to this higher phosphorus content. The highly siderophile element abundance patterns have been interpreted as reflecting strong partitioning during core formation in a magma ocean environment with little if any late veneer. Oxygen isotope data provide evidence for the relative proportions of chondritic components that were accreted to form Mars. However, the amount of volatile element depletion predicted from these models does not match that observed — Mars would be expected to be more depleted in volatiles than the Earth. The easiest way to reconcile these data is for the Earth to have lost a fraction of its moderately volatile elements during late accretionary events, such as giant impacts. This might also explain the non-chondritic Si/Mg ratio of the silicate portion of the Earth. The lower density of Mars is consistent with this interpretation, as are isotopic data. ⁸⁷Rb-⁸⁷Sr, ¹²⁹I-¹²⁹Xe, ¹⁴⁶Sm-¹⁴²Nd, ¹⁸²Hf-¹⁸²W, ¹⁸⁷Re-¹⁸⁷Os, ²³⁵U-²⁰⁷Pb and ²³⁸U-²⁰⁶Pb isotopic data for Martian meteorites all provide evidence that Mars accreted rapidly and at an early stage differentiated into atmosphere, mantle and core. Variations in heavy xenon isotopes have proved complicated to interpret in terms of ²⁴⁴Pu decay and timing because of fractionation thought to be caused by hydrodynamic escape. There are, as yet, no resolvable isotopic heterogeneities identified in Martian meteorites resulting from ⁹²Nb decay to ⁹²Zr, consistent with the paucity of perovskite in the martian interior and its probable absence from any Martian magma ocean. Similarly the longer-lived ¹⁷⁶Lu-¹⁷⁶Hf system also preserves little record of early differentiation. In contrast W isotope data, Ba/W and time-integrated Re/Os ratios of Martian meteorites provide powerful evidence that the mantle retains remarkably early heterogeneities that are vestiges of core metal segregation processes that occurred within the first 20 Myr of the Solar System. Despite this evidence for rapid accretion and differentiation, there is no evidence that Mars grew more quickly than the Earth at an equivalent size. Mars appears to have just stopped growing earlier because it did not undergo late stage (>20 Myr), impacts on the scale of the Moon-forming Giant Impact that affected the Earth.