The Circular Synthetic Radar

A new type of synthetic radar, the circular synthetic radar, uses a simple interferometer whose elements are mounted at the ends of a horizontal boom rotating about a vertical mast. Pulses are radiated alternately ?in-phase? and in ?phase-quadrature.? The returning echoes are also detected incoherently, both ?in-phase? and in ?phase-quadrature.? The four distinct outputs are fed into an on-line computer which, after a Fourier analysis, synthesizes a mapping function of the azimuthal distribution of targets.     

Closed-Form Expressions for Noncoherent Radar Integration Gain and Collapsing Loss

Closed-form formulas allow rapid determination of noncoherent integration gain and integration loss when the single-sample IF signal-to-noise ratio (SNR) is known. In addition, if the required SNR is known for any number of integrated pulses, the required SNR for any other number is easily determined. A closed-form expression is given for radar collapsing loss, expressed in terms of the equivalent integrated signal-to-noise ratio required to produce a given combination of false-alarm and detection probabilities. Alternatively, the single-sample signal-to-noise ratio of a set of samples may be used together with the closed-form expression for integration gain to get the equivalent integrated signal-to-noise ratio.     

Changes in the amino acid code.

The genetic code is characterized by a pattern arising from "wobble-pairing" between codons and anticodons, so that one nucleotide in the first anticodon position can pair with more than one nucleotide in the third position of a codon. Earlier codes may have existed in which there were fewer anticodons than at present, so that these earlier codes contained fewer amino acids. The universal code was formerly thought to be the only currently existing code used by terrestrial species. It is now known that differences exist from the universal code in mitochondrial coding systems, and also that mitochondrial systems differ from each other. These findings lend support to the proposal that archetypal codes preceded the present universal code. Such archetypal codes may have had some resemblances to mitochondrial codes.     

Cardiovascular effects of simulated zero-gravity in humans

Head-down and head-up [correction of heat-up] tilted bedrest (5 degrees) and head out water immersion (HOWI) for 6 hr were compared. Parameters: Cardiac output (rebreathing method), blood pressure (arm cuff), forearm blood flow (venous occlusion plethysmography), total peripheral (TPR), and forearm vascular (FVR) resistances, Hct, Hb, relative plasma volume (PV) changes, and plasma catecholamines (single-isotope assay). During HOWI there was as expected a decrement in TPR, FVR, Mean arterial pressure (MAP, from 100 to 80 mmHg), Hct, and PV, and--as a new finding--catecholamines, which were 30-50% lower compared with both +5 and -5 degrees bedrest. During head down tilt, MAP was elevated (to 100-110 mmHg) and catecholamines did not fall, while TPR and EVR slowly decreased over 6 hr. HOWI is a stronger stimulus than -5 degrees bedrest, probably because HOWI elevates central venous pressure more markedly emptying the peripheral veins, while bedrest permits a distension of veins, which induces an increase in sympathetic nervous activity.     

Italy's contribution, from a medical standpoint, to the space safety of payload scientists, and perspectives for the future

In Italy, the selection of the Italian payload scientists has been performed according to the Spacelab Program of ESA. Twenty-four subjects underwent a screening performed by the Health Service of Italian Air Force. They were requested to pass an exercise test on treadmill and another ten-minute test on centrifuge, subject to the effect of +3 Gz. The authors briefly describe the results of the test. Noteworthy is the determination of Central Flicker Fusion Frequency. This parameter makes it possible to assess the endurance level of the subject, much earlier than other techniques (e.g. EKG). The importance of an accurate preliminary screening is emphasized as well as of successive training periods. Future studies will be undertaken to compare evoked cortical potentials with behaviour parameters of space safety, with a view to setting up a subtle tool of evaluation for both future candidates and payload scientists.     

The variable X-ray spectrum of Cyg XR-1

The variability of the X-ray spectrum of the discrete source Cyg XR-1 (α = 19^h 56^m δ = +35°.1) is reviewed. The variations observed in the energy region accessible to balloon borne detectors (energies greater than 20 keV) can be explained by assuming them to be caused by the eclipsing properties of a binary system. It is suggested that the system is composed of a source of small angular extent having a spectrum similar to that of a black body at approximately 1.5 × 10⁸ K (kT= 12.5 keV) and a non X-radiating companion which eclipses it at intervals of 2.9850 days. The system would be surrounded by an X-radiating plasma whose photon flux between 1 and 100 keV can be approximated by a power law spectrum whose exponent is — 1.7.     

X-ray scattering by intergalactic dust

The imaging capabilities of the Exosat and Einstein satellites at soft X-ray wavelengths have begun to show that suitable Galactic X-ray sources have extended ( 10 arcmin) haloes due to scattering of soft X-rays by interstellar dust. A simple argument suggests that similar haloes, due to scattering by intergalactic dust, should exist around distant (z 1) quasars and detailed analysis confirms this conclusion. A search for such haloes around suitable X-ray quasars could provide valuable, model-independent, constraints on the amount and origin of intergalactic dust.     

Position-Location Solutions by Taylor-Series Estimation

Taylor-series estimation gives a least-sum-squared-error solution to a set of simultaneous linearized algebraic equations. This method is useful in solving multimeasurement mixed-mode position-location problems typical of many navigational applications. While convergence is not proved, examples show that most problems do converge to the correct solution from reasonable initial guesses. The method also provides the statistical spread of the solution errors.     

Experiments with injection of powerful plasma jet into the ionosphere

This paper describes two rocket experiments “Aelita” with high power lithium plasma injection. The results of onboard magnetometer, massspectrometer, photometer, plasma, corpuscular and ground radar measurements are given. Dynamics and structure of plasma formation are discussed.