Automatic Inspection and Diagnostic System for Army Tactical Vehicles

A tactical system designed to inspect and diagnose malfunctions in all army tactical vehicles including jeeps, trucks, and tanks is known as Ready Multipurpose Automatic Inspection and Diagnostic System (READYMAIDS). The laboratory model developed to prove the feasibility of design is discussed together with design problems such as instrumenting a vehicle without modifications. The system uses a small digital computer in addition to switching, measurement, and loading devices. These devices are integrated into a small transportable unit. Results to date, problem areas, and possible solutions are described.     

G2-chromosome aberrations induced by high-LET radiations.

We report measurement of initial G2-chromatid breaks in normal human fibroblasts exposed to various types of high-LET particles. Exponentially growing AG 1522 cells were exposed to gamma rays or heavy ions. Chromosomes were prematurely condensed by calyculin A. Chromatid-type breaks and isochromatid-type breaks were scored separately. The dose response curves for the induction of total chromatid breaks (chromatid-type + isochromatid-type) and chromatid-type breaks were linear for each type of radiation. However, dose response curves for the induction of isochromatid-type breaks were linear for high-LET radiations and linear-quadratic for gamma rays. Relative biological effectiveness (RBE), calculated from total breaks, showed a LET dependent tendency with a peak at 55 keV/micrometer silicon (2.7) or 80 keV/micrometer carbon (2.7) and then decreased with LET (1.5 at 440 keV/micrometer). RBE for chromatid-type break peaked at 55 keV/micrometer (2.4) then decreased rapidly with LET. The RBE of 440 keV/micrometer iron particles was 0.7. The RBE calculated from induction of isochromatid-type breaks was much higher for high-LET radiations. It is concluded that the increased production of isochromatid-type breaks, induced by the densely ionizing track structure, is a signature of high-LET radiation exposure.     

Reflections on the quest for international cooperation

Changed political objectives, straitened economic circumstances and an altered balance of capability and expertise in space endeavours have together produced more discussion of the need for international cooperation than ever before, but the meaning of the term has subtly shifted. Insisting on US ‘leadership’ is self-defeating; what is instead firmly desired by the USA's potential partners is a balanced relationship in which each nation makes an identifiable contribution and takes the lead in at least one of a package of projects. If this is going to happen, there must be an international forum or framework in which projects can be discussed and agreed. This in turn requires initiative at governmental level.     

M-FISH analysis of chromosome aberrations in human fibroblasts exposed to energetic iron ions in vitro.

Confluent human fibroblast cells were exposed to 6 Gy gamma-rays or 200 MeV/nucleon Fe ions at 0.7 or 3 Gy. The cells were allowed to repair for 24 hours after exposure and chromosomes were collected using a premature chromosome condensation technique with calyculin-A. Chromosome aberrations were analyzed using the multicolor FISH (mFISH) technique that allows identification of both complex and truly incomplete exchanges. Results showed that both doses of the Fe ions produced higher ratios of complex to simple exchanges and lower ratio of complete to incomplete exchanges than the 6 Gy gamma-exposure. The ratios of aberration yields were similar for the two doses of Fe ions. After 0.7 Gy of Fe ions, most complex aberrations were found to involve three or four chromosomes, indicating this is the maximum number of chromosome domains traversed by a single Fe ion track.     

The Origin of Primary Cosmic Rays: Constraints from ACE Elemental and Isotopic Composition Observations

Cosmic-ray isotope observations from NASAs Advanced Composition Explorer (ACE) mission have been used to investigate the composition of cosmic-ray source material. Source abundances relative to ⁵⁶Fe are reported for eleven isotopes of Ca, Fe, Co, and Ni, including the very rare isotopes ⁴⁸Ca and ⁶⁴Ni. Although the source abundances range over a factor 10⁴, most of the ratios to ⁵⁶Fe are consistent with solar-system values to within 20%. However, there are some notable differences, the most significant being an excess of (70±30)% relative to the solar system for the cosmic-ray source ratio ⁵⁸Fe/⁵⁶Fe. The possible association of such an excess with a contribution to the cosmic-ray source from Wolf–Rayet star ejecta is discussed.     

The abundance of atomic 1H, 4He and 3He in the local interstellar cloud from pickup ion observations with SWICS on Ulysses

Pickup ions measured deep inside the heliosphere open a new way to determine the absolute atomic density of a number of elements and isotopes in the local interstellar cloud (LIC). We derive the atomic abundance of hydrogen and the two isotopes of helium from the velocity and spatial distributions of interstellar pickup protons and ionized helium measured with the Solar Wind Ion Composition Spectrometer (SWICS) on the Ulysses spacecraft between 2 and 5 AU. The atomic hydrogen density near the termination shock derived from interstellar pickup ion measurements is 0.115±0.025 cm^–3 and the atomic H/He ratio from these observations is found to be 7.7 ± 1.3 in the outer heliosphere. Comparing this value with the standard universal H/He ratio of 10 we conclude that filtration of hydrogen is small and that the ionization fraction of hydrogen in the LIC is low.     

Book reviews

Space Science Reviews -     

ROSAT PSPC spectra of six Seyfert 1 galaxies

We present six ROSAT PSPC observations of Seyfert 1 galaxies chosen to have low Galactic line-of-sight absorption (N_H 10²⁰ cm⁻²). As expected, it is found that all of these sources possess significantly steeper spectra below 1 keV, than that observed at higher X-ray energies. In addition we find evidence for soft X-ray spectral features, which are best parameterized as line emission at 0.63 keV in NGC7469 and 0.75 keV in ESO198-G24. We examine these results in the light of the accuracy of the PSPC spectral calibration.     

An Improved Piezoelectric Balance for Aerodynamic Force

A method for measuring model forces in the shock tunnel by means of an acceleration-compensated balance has been reported by the authors.1 Since that time, a continuing program of research and development on advanced shock-tunnel instrumentation at Cornell Aeronautical Laboratory, Inc. has led to a promising new balance configuration. This balance is inherently more compact than previous designs, and allows testing of higher lift/drag (L/D) configurations than before. The increased high-pressure capability of the shock tunnel, and the growing recognition of the importance of the shock tunnel as a means of generating large Reynolds number flow, have thus added to the importance of this new higher load, more compact balance concept. An experimental balance has been built and calibrated. The performance of this balance is presented in this paper.