Auroral electrons

Satellite and rocket measurements of auroral electrons (which have been made since Brown's (1966) and Pfister's (1967) papers have appeared) are reviewed, and the salient characteristics of auroral electrons which emerge from all types of measurements are summarized. Effects of the atmosphere on the energy distribution of electron fluxes are discussed. Ionization rates associated with typical fluxes are derived. Observable effects produced in the atmosphere and the fate of auroral electrons are briefly described.This paper does not discuss the role of auroral protons (or particles). A recent review on the subject has been given by Eather (1967).     

The Design of Huffman Sequences

The paper presents a method by which the zeros of the polynomial representing a Huffman (impulse-equivalent) pulse sequence can be chosen so as to exert a degree of control on the form of the energy distribution of the signal in the time-frequency plane. This makes it possible to design Huffman pulse sequences which are suitable for use as radar or sonar signals in situations where significant target velocity occurs.     

Have deoxyribonucleotides and DNA been among the earliest biomolecules?

Unlike ribose chemistry, the chemistry of 2-deoxyribose precludes its formation or at least its incorporation into nucleotides under accepted "primordial soup" conditions; therefore RNA and DNA could not develop in parallel during the evolution of protocells. However, deoxyribonucleotides might have been formed abiotically by direct reduction of ribonucleotides in a primitive version of the biochemical pathway. This sequence of events, in which DNA lagged behind RNA in the assembly of genetic information for an unknown--probably short--period of time is suggested by the primitive traits (i.e., nucleotide binding, thiol redox chemistry, and metal ion catalysis) of present-day enzyme systems of deoxyribonucleotide biosynthesis. The reaction should be amenable to experimental study.     

Hydroelectrolytic and hormonal modifications related to prolonged bedrest in antiorthostatic position

The effects of prolonged bedrest in antiorthostatic position (-4 degrees head down) on electrolyte balance were studied in 4 young volunteers. An increase was noted in sodium excretion during the first 4 days. Plasma renin activity and plasma aldosterone varied in parallel manner during the same period. Potassium balance and creatinine clearance were not significantly modified. In light of these data we feel that prolonged bedrest in antiorthostatic position constitutes an effective way to simulate on earth metabolic and hormonal modifications occurring in man under weightlessness conditions.     

Ionospheric gas dynamics of satellites and diagnostic probes

The gas dynamics of interactions of a tenuous ionosphere with moving satellites and probes that have bearings on the diagnostics of the ionosphere are discussed. Emphasis is on the cases where the body is moving at mesothermal speeds, namely intermediate between the thermal speeds of ions and electrons of the ambient ionosphere. Methods of collision-free plasma kinetics with self-consistent field are used. The development of the topics for discussion starts with stationary Langmuir probe which entails the basic mechanism of body-plasma interaction that becomes further intricated as the body moves at a higher and higher speed. Applications of the theory of plasma interaction to meteors which move in the ionosphere are also presented.     

Gravity and perceptual stability during translational head movement on earth and in microgravity

We measured the amount of visual movement judged consistent with translational head movement under normal and microgravity conditions. Subjects wore a virtual reality helmet in which the ratio of the movement of the world to the movement of the head (visual gain) was variable. Using the method of adjustment under normal gravity 10 subjects adjusted the visual gain until the visual world appeared stable during head movements that were either parallel or orthogonal to gravity. Using the method of constant stimuli under normal gravity, seven subjects moved their heads and judged whether the virtual world appeared to move “with” or “against” their movement for several visual gains. One subject repeated the constant stimuli judgements in microgravity during parabolic flight. The accuracy of judgements appeared unaffected by the direction or absence of gravity. Only the variability appeared affected by the absence of gravity. These results are discussed in relation to discomfort during head movements in microgravity.     

A search for chiral signatures on Mars

It is thought that the chiral molecules of living material can induce circular polarization in light at levels much higher than expected from abiotic processes. We therefore obtained high quality imaging circular polarimetry of the martian surface during the favorable opposition of 2003 to seek evidence of anomalous optical activity. We used two narrow-band filters covering 43% of the martian surface, 15% of it in-depth. With polarization noise levels <0.1% (4.3 upper limits 0.2-0.3%) and spatial resolution 210 km, we did not find any regions of circular polarization. When data were averaged over the observed face of the planet, we did see a small non-zero circular polarization 0.02%, which may be due to effects associated with the opposition configuration though it is at the limit of the instrumental capability. Our observations covered only a small fraction of parameter space, so although we obtained a null result, we cannot exclude the presence of optical activity at other wavelengths, in other locations, or at higher spatial resolution.     

Angular Velocity Measurement Using Rate Gyros in a Spinning Vehicle

It is shown that when the gyro spin vector is in opposition to the spin vector of the vehicle, the output differential equation of the gyro becomes unstable for large vehicle spin values. When the gyro is used with its spin vector along the spin vector of the vehicle, the steady-state response of the gyro is a nonlinear function of the roll rate of the vehicle.     

Electric Field Detection and Ranging of Aircraft

The electric field transported by charged aircraft during free flight can be observed quantitatively in distances of up to some 100 m. A system of three plane sensors arranged in the corners of a triangle or the Earth surface is described, by which the flight path of aircraft is detected in the range of 40 to 500 m with velocities of approximately 50 m/s. The theory and typical experimental results are discussed.