A noise insensitive solution to an ambiguity problem in spectralestimation

The instantaneous frequency measurement (IFM) receiver is capable of measuring the center frequency of single frequency pulses over a wide range (bandwidth) of center frequencies. Because of various constraints, the frequency resolution requirement results in long correlator delay times that reduce the single correlator bandwidth. A large bandwidth can be achieved only if two or more correlators are used. The problem of estimating frequency is then reduced to the simultaneous congruence problem of number theory. A design procedure is presented for solving the congruence problem for a given amount of noise protection, a stated frequency resolution, a minimum bandwidth, and a fixed level of precision (bits) in the IFM receiver     

Decoding techniques in state estimation for dynamic systems withpast histories

States of dynamic models with a higher order memory are estimated using both a stack sequential decoding algorithm and the Viterbi decoding algorithm (VDA), without higher dimensional dynamic system representation. This results in memory reduction for state estimate implementation. It is found that state estimation with a stack sequential decoding algorithm is faster and more practical than the state estimation with the Viterbi decoding algorithm, even though the estimates obtained by the Viterbi decoding algorithm are superior     

A Major Step in Series Regulators

Power hybrid microelectronic design techniques have been developed to satisfy the requirements of 10-ampere 100-watt series voltage regulators. Application of these new techniques has resulted in a package occupying roughly the same volume as a TO-63 power transistor, yet containing two 30-ampere power transistors, selectable external components, and associated control circuitry.     

Frame Synchronization in the Presence of Errors and Erasures

An approach to the problem of achieving frame synchronization in the presence of jamming or other large disturbances is presented. It is assumed that the disturbance can be detected at the receiver, which then erases the corresponding bits and passes this information to the synchronizer. A synchronization algorithm designed to operate in the presence of both erasures and background errors is described and evaluated for a representative set of system parameters. This algorithm is shown to have a significant advantage over an algorithm which does not use the location information inherent in the erasure model.     

Confirmation of gravisensitivity in the slime mold physarum polycephalum under near weightlessness

We have investigated Physarum polycephalum, a unicellular organism with no special gravity receptors, on its ability to react to gravity. The first experiments were 0 g-simulation experiments on the fast-rotating clinostat conducted with plasmodial strands of this acellular slime mold. In these earth-bound experiments the observed parameters were periodicity of the contractions and dilatations of the strand's ectoplasm as well as the periodicity and velocity of the striking cytoplasmic (endoplasmic) shuttle streaming. During 0 g-simulation these parameters showed significant changes indicating the existence of a gravisensitivity of the slime mold.

The Space-Shuttle experiment (ESA-Biorack in D 1-Mission) should demonstrate the validity of the 0 g-simulation on the fast-rotating clinostat. The experiment was designed in a way enabling the registration of the same parameters as on the clinostat (using the light microscope in combination with a photo diode and a cinecamera). Only one of the two planned measurement sessions was fully successful and provided us with data confirming the results gained on the fast-rotating clinostat: The slime mold showed under real near weightlessness in the D 1-Space Shuttle Mission a transient frequency increase in its contraction rhythmicity and a (steady) increase in the streaming velocity of its endoplasm.     

Effects of prolonged exposure to space flight factors for 175 days on lettuce seeds

We have studied the effects of prolonged (up to 175 days) exposure of $\text{Lactuca sativa}$ seeds to space flight factors, including primary cosmic radiation heavy ions. The data obtained evidence a significant fourfold increase ofs pontaneous mutagenesis in seeds both with regard to the total number of aberrant cells as well as the formation of single cells with multiple aberrations. Comparison of the present experiment with earlier works shows that the frequency of such aberrations increases with the duration of the flight.     

Microorganisms and biomolecules in space environment experiment ES 029 on Spacelab-1.

Bacterial spores are proper test organisms for studying problems of space biology and exobiology. During the Spacelab 1 mission, studies on the limiting factors for survival of Bacillus subtilis spores in free space have been performed. An exposure tray on the pallet of Spacelab 1 accomodated 316 samples of dry spores for treatment with space vacuum and/or the following selected wavelengths of solar UV: > 170 nm, 220 nm, 240nm, 260nm and 280 nm. After recovery, inactivation, mutation induction, reparability, and photochemical damages in DNA and protein have been studied. The results contribute to the understanding of the mechanisms of increased UV sensitivity of bacterial spores in vacuo and to a better assessment of the chance of survival of resistant forms in space and of interplanetary transfer of life.