Neon and Helium in the Surface of Stardust Cell C2028

Previous studies of light noble gases in Stardust aerogel samples detected a variety of isotopically non-terrestrial He and Ne compositions. However, with one exception, in none of these samples was there visible evidence for the presence of particles that could have hosted the gases. The exception is materials keystoned from track 41, cell C2044, which contained observable fragments of the impacting Wild 2 comet coma grain. Here we report noble gas data from a second aerogel sample in which grains are observed, cut from the surface of a cell (C2028) riddled with tiny tracks and particles that are thought to be secondary in origin, ejected toward the cell when a parent grain collided with the spacecraft structure and fragmented. Interestingly, measured 20Ne/22Ne ratios in the track 41 and C2028 samples are similar, and within error of the meteoritic "Q-phase" Ne composition

Anatomy of a cluster IDP. Part 2: Noble gas abundances, trace element geochemistry, isotopic abundances, and trace organic chemistry of several fragments from L2008#5

The topics discussed include the following: noble gas content and release temperatures; trace element abundances; heating summary of cluster fragments; isotopic measurements; and trace organic chemistry

Light Element Isotopic Compositions of Cometary Matter Returned by the STARDUST Mission

Hydrogen, carbon, nitrogen, and oxygen isotopic compositions are heterogeneous among comet 81P/Wild2 particle fragments, however extreme isotopic anomalies are rare, indicating that the comet is not a pristine aggregate of presolar materials. Non-terrestrial nitrogen and neon isotope ratios suggest that indigenous organic matter and highly volatile materials were successfully collected. Except for a single circumstellar stardust grain, silicate and oxide minerals have oxygen isotopic compositions consistent with solar system origin. One refractory grain is {sup 16}O-enriched like refractory inclusions in meteorites, suggesting formation in the hot inner solar nebula and large-scale radial transport prior to comet accretion in the outer solar system

The Interaction of Age and Diagnosis in Neuropsychological Test Results

The effects of age on neuropsychological test performance is an important issue in clinical diagnostic work. Although there is general agreement on the effects of age on control patients, there is considerable controversy over age effects in a neurological population. Two major reasons may be responsible for discrepant results across studies: biased subject populations and inadequate statistical procedures. The present study corrected for these problems, examining the test performance of 171 subjects classified by age (above 35, 35 and below) and diagnosis (right, left, diffuse, control). A weighted means analysis of variance found 7 significant age effects on 15 measures taken from the Halstead-Reitan. All measures showed significant Fs due to differences in diagnostic groups. No significant interaction effects were found. The results clearly support the contention that age effects are identical in the control and brain-injured groups. This indicates that age corrections based on the performance of a normal group are likely to be useful in increasing neurodiagnostic accuracy rates

Evidence for a Dominant Component of Solar-Energetic-Particle (SEP) Helium and Neon in a Suite of Interplanetary Dust Particles

Most of the 12 IDPs analyzed in this study are surprisingly rich in SEP gases, unaccompanied by a significant component due to solar-wind irradiation. Estimates of the SEP/SW fluence ratio from these data are 10–3 to 10–4