Gravitropism in cut flower stalks of snapdragon.

The negative gravitropic response of cut flower stalks is a complex multistep process that requires the participation of various cellular components acting in succession or in parallel. The process was particularly characterized in snapdragon (Antirrhinum majus L.) spikes with regard to (1) gravity stimulus perception associated with amyloplast reorientation; (2) stimulus transduction mediated through differential changes in the level, action and related genes of auxin and ethylene and their possible interaction; (3) stimulus response associated with differential growth leading to stalk curvature; (4) involvement of cytosolic calcium and actin cytoskeleton. Results show that the gravity-induced amyloplast reorientation, differential over-expression of two early auxin responsive genes and asymmetrical distribution of free IAA are early events in the bending process. These precede the asymmetrical ethylene production and differential stem growth, which was derived from initial shrinkage of the upper stem side and a subsequent elongation of the lower stem side. Results obtained with various calcium- and cytoskeleton-related agents indicate that cytosolic calcium and actin filaments may play essential roles in gravitropism-related processes of cut flower stalks. Therefore, modulators of these two physiological mediators may serve as means for controlling any undesired gravitropic bending.     

Main characteristics of biological components of developing life support system observed during the experiments aboard orbital complex MIR.

Since 1990, the orbital complex MIR has witnessed several incubator experiments for determination of spaceflight effects on embryogenesis of Japanese quail. First viable chicks who had completed the whole embryological cycle in MIR microgravity hatched out in 1990; it became clear that newborns would not be able to adapt to microgravity unaided. There were 8 successful incubations of chicks in the period from 1990 to 1999. In 1995-1997 the MIR-NASA space science program united Russian and US investigators. As a result, experiments Greenhouse-1 and 2 were performed with an effort to grow super dwarf wheat from seed to seed, and experiment Greenhouse-3 aimed at receiving two successive generations of Brassica rapa. But results of these experiments could not be used for definitive conclusions concerning effects of spaceflight on plant ontogenesis and, therefore, experiments Greenhouse-4 and 5 were staged within the framework of the Russian national space program. The experiments finally yielded wheat seeds. Some of the seeds was left on the space station and, being planted, gave viable seedlings which, in their turn, produced the second crop of space seeds.     

Evaluation of built-in test

Built-in test (BIT) provides fault finding as a means to aid in system assembly, test, and maintenance. An investigation to evaluate BIT of a particular electronics board used in the in-flight entertainment system for Boeing 777s is described. We found BIT proved useful when failure occurrences were uniquely associated with the operating environment, situations which can result in no-fault found, or could-not duplicate (CND) failures upon test. We also observed cases where the BIT failed to observe failures, and in some cases pointed to the wrong cause of failure. These and other advantages and disadvantages of BIT implementation are discussed     

The Use of Television Signals of Stationary Television Centers for Navigation Determination of Low-Orbit Satellites

For systems of autonomous satellite navigation, it is proposed to use television signals of stationary television centers positioned along the flight path in the band of satellite radio coverage as sources of primary navigation information. Television signal processing allows one to determine the time instants of transit through traverses of the television centers. An algorithm of calculating the parameters of satellite motion by times of transit through traverses is developed.     

A Proposal for Constructing a Group of Space Objects for Solving Transport and Energy Problems

We propose to develop a scheme for a group of space objects which includes a set of orbital tethers and exchange masses. These objects are injected into circumterrestrial orbits. A variety of problems can be solved with the help of this space system, namely, transport problems and problems of converting the electric power generated onboard spacecraft into mechanical energy of motion of the space objects. In the future, natural celestial bodies (in particular, the Moon) can be considered as elements of the system. This opens up the possibility of using the energy of motion of the Moon both for solving transport problems and for generating electric power onboard spacecraft.     

On different sensitivities of microorganisms to lowered gravitation

The influence of lowered gravitation on biomass and CO₂ production in $\text{B.megaterium}$, a xerophyte, and $\text{Spirillum azotocolligens}$, an aqueous spirillum, in liquid nutrient medium on a horizontal clinostat at 0.1 $\text{g}$ has been studied. As controls we considered: 1) growth under stationary conditions of cultivation with test tubes oriented horizontally; 2) growth on a synchronously revolving centrifuge; and 3) growth on a swing with stirring. A horizontal clinostat at 0.1 g stimulates biomass production and CO₂ release in $\text{B.megaterium}$ as compared with the controls. $\text{Spirillum azotocolligens}$ growth is reduced as a result of clinostating. The best development and CO₂ production are observed under stationary conditions. The results do not support the assumption that microorganisms living in water are more resistant to lowered gravitation than those living in soil.     

Fractal interpolation of radar signatures for detecting stationarytargets in ground clutter

The fundamentals of fractal geometry are reviewed, and its application to the millimeter-wave radar detection of stationary targets in a clutter background is described. First, high-range-resolution (HRR) profiles are used to determine the fractal interpolation functions needed to create fractal signatures. The fractal dimension is then determined for these signatures. On the basis of the value of the fractal dimension, the signature is declared to represent either a target of interest or clutter. The results of a CFAR (constant false alarm rate) simulation are presented to illustrate the performance of the method. They indicate that the fractal dimension feature used seems to be independent of amplitude. Thus, the fractal dimension information combined with traditional amplitude processing techniques will improve probabilities of detection     

Measurements of the artificially stimulated precipitation of electrons from the inner radiation belt in the experiment “SPOLOKH-2”

Evidence for an enhancement of the electron flux associated with a barium chaped charge release from “SPOLOKH-2” rocket payload, launched from Volgograd (L = 2.2) on June 29, 1978, will be presented. There is also evidence for a periodic train of particle bursts occurring with about 11 second period during more than 100 seconds after the release. The observed phenomena is interpreted as a “trigger-effect”.     

Loss in Single-Channel MTI with Post-Detection Integration

The detection performance of a single-channel MTI receiver with post-detection integration, for a Swerling I target, has been evaluated by a Monte Carlo simulation. It is shown that a fairly good approximation is obtained by applying the ?effective number of independent integrated samples? to the standard detection curves. The ?I-only? loss is about 2 dB for integration of more than 20 pulses; thus this receiver is acceptable if implementation constraints dictate it.