Limiting Performance of Generalized Sign Test Detector

The limiting performance of the generalized sign test detector as the number M of target returns becomes infinite has been derived by Hansen and Olsen [1]. Simple expressions are derived herein for the limiting performance for finite M as K, the number of noise samples in the reference set, becomes infinite. Curves are presented which indicate how this limiting performance is approached as K is increased for both constant target returns and fluctuating target returns.     

Boresight Corection Using Unlocated Targets

Boresight correction on detected but unlocated targets may be made if a bearing (whose error is unknown) is repeated on two seeker headings and another bearing is repeated on two seeker headings, or if bearing is repeated on three seeker headings. The assumption is made that seeker position and heading are known. The procedure is effective either with the above or with the combination of restricted seeker travel and intermittent target detection.     

Properties of the neutral density and composition in the thermosphere

Measurements of the density and composition of the thermosphere between 150 and 500 km, which were obtained by the S3-1 satellite, have been compared with the Jacchia and MSIS models. The measurements of the densities of O, N₂, N and Ar show some differences from the current models which should be considered during the preparation of the next CIRA model. The Ar measurements are particularly useful in examining the response of the neutral atmosphere to geomagnetic heating. These results are useful in establishing the appropriate lower boundary conditions for modeling of the thermosphere.     

Effects of the diet on brain function.

The rates of synthesis by brain neurons of the neurotransmitters serotonin, acetylcholine, and the catecholamines depend on the brain levels of the respective precursor molecules. Brain levels of each precursor are influenced by their blood concentration, and for the amino acid precursors, by the blood levels of other amino acids as well. Since diet readily alters blood concentrations of each of these precursors, it thereby also influences the brain formation of their neurotransmitter products.     

Equatorial F-region ionization differences between March and September, 1979

Ionospheric total electron content and the F-region maximum electron density at a number of stations in the equatorial region, during the recent solar activity maximum period 1979 to 1980, show significant differences between the two equinoctial periods. Ionization during the month of March is higher than in September, irrespective of the station location both in northern and southern hemispheres, and in different longitude sectors. The observed pattern is compared with those predicted by different models, in particular with one of the authors which includes processes such as ionization production, loss, electrodynamic drifts, winds and global composition changes involved in the equatorial ionosphere. It is found that a change in the neutral composition is primarily responsible for the observed F-region density differences between March and September.     

Cometary habitats for primitive life.

Comet Halley studies indicate most of the nucleus is covered by an insulating crust, presumed of pyrolysed organic material. The subcrust is warmed and percolated by gases within 2AU, so provides one habitat for primitive replicating organisms. Cracks and crevices within contaminated ice in the craters provides a habitat for photosynthesising organisms. Subsurface lakes on the Europa model, though insulated by some metres of ice, would require a trigger (perhaps meteorite impact and energy source (chemical or metabolic energy) to initiate and maintain a suitable-habitat on short period comets. Constraints on transfer between comets and other planetary bodies implies that radiation-resistant species with lengthy hibernation potential would be expected.     

Extragalactic radio sources

Some recent observational results on extended and compact extragalactic radio sources are described. Theoretical interpretations are critically examined.     

The implantation of life on Mars: feasibility and motivation.

Environmental conditions on Mars are extremely hostile, and would be destructive to any organisms which might arrive there unprotected to-day. However, it is a biocompatible planet. Its unalterable astrophysical parameters would allow the maintenance of a much thicker, warmer carbon dioxide atmosphere than that which currently exists. Though very cold (averaging about -60 degrees C), highly oxidizing and desiccated, Mars may possess substantial quantities of the materials needed to support life--in particular, water and carbon dioxide. A general scenario for implanting life on Mars would include three main phases: (1) robotic and human exploration to determine whether sufficiently large and accessible volatile inventories are available; (2) planetary engineering designed to warm the planet, release liquid water and produce a thick carbon dioxide atmosphere; and (3) if no indigenous Martian organisms emerge as liquid water becomes available, a program of biological engineering designed to construct and implant pioneering microbial communities able to proliferate in the newly clement, though still anaerobic, Martian environment. The process of establishing an ecosystem, or biosphere, on a lifeless planet is best termed 'ecopoiesis.' This new word, derived from Greek, means 'the making of an abode for life.' It is by no means clear whether ecopoiesis on Mars is scientifically possible or technologically achievable. Thus we urge that it be one of the objectives of space research during the next century to assess the feasibility of ecopoiesis on Mars.     

The Galileo Probe Atmosphere Structure instrument

The Galileo Probe Atmosphere Structure Instrument will make in-situ measurements of the temperature and pressure profiles of the atmosphere of Jupiter, starting at about 10^-10 bar level, when the Probe enters the upper atmosphere at a velocity of 48 km s^-1, and continuing through its parachute descent to the 16 bar level. The data should make possible a number of inferences relative to atmospheric and cloud physical processes, cloud location and internal state, and dynamics of the atmosphere. For example, atmospheric stability should be defined, from which the convective or stratified nature of the atmosphere at levels surveyed should be determined and characterized, as well as the presence of turbulence and/or gravity waves. Because this is a rare opportunity, sensors have been selected and evaluated with great care, making use of prior experience at Mars and Venus, but with an eye to special problems which could arise in the Jupiter environment. The temperature sensors are similar to those used on Pioneer Venus; pressure sensors are similar to those used in the Atmosphere Structure Experiment during descent of the Viking Landers (and by the Meteorology Experiment after landing on the surface); the accelerometers are a miniaturized version of the Viking accelerometers. The microprocessor controlled experiment electronics serve multiple functions, including the sequencing of experiment operation in three modes and performing some on-board data processing and data compression.     

The team ROC curve in a binary hypothesis testing environment

We consider the distributed detection problem, in which a set of decision makers (DMs) receive observations of the environment and transmit finite-valued messages to other DMs according to prespecified communication protocols. A designated primary DM makes the find decision on one out of two alternative hypotheses. All DMs make decisions, in order to maximize a measure of organizational performance. We discuss three different types of decision rules (deterministic, independent randomization, and dependent randomization), and their implications on the organizational performance. Each DM is described by its individual receiver operating characteristic (ROC) curve, which is concave. We determine that concavity is not guaranteed for the case of the ROC curve of a team of DMs, even if the decision rules are perfectly continuous and if the individual ROC curves are strictly concave and smooth unless dependent randomization is allowed