Spatial variation of iron abundance in the high speed solar wind, 1972 to 1976

The Fe/H ratios in the peaks of high speed streams (HSS) during the decline of Solar Cycle 20 and the following minimum (October 1972-December 1976) were analyzed. The response of the 50-200 keV ion channel of the APL/JHU energetic particle experiment (EPE) on IMP-7 and 8 to solar wind iron ions at high solar wind speeds and Fe measurements were compared with solar wind H and He parameters from the Los Alamos National Laboratory (LANL) instruments on the same spacecraft. In general, the Fe distribution parameters (bulk velocity, flow direction, temperature) are found to be similar to the LANL He parameters. Although the average Fe/H ratio in many steady HSS peaks agrees within observational uncertainties with the nominal coronal ratio of 4.7 x 10(-5), abundance variations of a factor of up to 6 are obtained across a given coronal-hole associated HSS. Over the period 1973-1976, a steady decrease in the average quiet-time Fe/H ratio by a factor of about 4 is measured on both IMP-7 and 8

Solar wind iron abundance variations at solar wind speeds up to 600 km s sup -1, 1972 to 1976

The Fe/H ratios in the peaks of high speed streams (HSS) were analyzed during the decline of Solar Cycle 20 and the following minimum (October 1972 to December 1976). The response of the 50 to 200 keV ion channel of the APL/JHU energetic particle experiment (EPE) on IMP-7 and 8 was utilized to solar wind iron ions at high solar wind speeds (V or = 600 km/sec). Fe measurements with solar wind H and He parameters were compared from the Los Alamos National Laboratory (LANL) instruments on the same spacecraft. In general, the Fe distribution parameters (bulk velocity, flow direction, temperature) are found to be similar to the LANL He parameters. Although the average Fe/H ration in many steady HSS peaks agrees within observational uncertainties with the nominal coronal ratio of 4.7 x 0.00001, abundance variations of a factor of up to 6 are obtained across a given coronal-hole associated HSS

Multiple spacecraft observations of interplanetary shocks: Characteristics of the upstream ULF turbulence

All interplanetary shocks observed by ISEE-3 and either ISEE-1 or ISEE-2 or both in 1978 and 1979 are examined for evidence of upstream waves. In order to characterize the properties of these shocks it is necessary to determine accurate shock normals. An overdetermined set of equations were inverted to obtain shock normals, velocities and error estimates for all these shocks. Tests of the method indicate it is quite reliable. Using these normals the Mach number and angle were between the interplanetary magnetic field and the shock normal for each shock. The upstream waves were separated into two classes: whistler mode precursors which occur at low Mach numbers and upstream turbulence whose amplitude at Mach numbers greater than 1.5 is controlled by the angle of the field to the shock normal. The former waves are right hand circularly polarized and quite monochromatic. The latter waves are more linearly polarized and have a broadband featureless spectrum

Simultaneous measurements of magnetotail dynamics by IMP spacecraft

Changes in tail energy density during substorms in the magnetotail are given. In addition to plasma sheet thinnings seen prior to substorm onsets, a gradual decrease in plasma beta was detected in the deep tail which precedes onset and the more prominent plasma disappearance that typically accompanies it. The frequency of thinnings and the regions over which they occurred indicate that drastic changes in plasma sheet thickness are common features of substorms which occur at all locations across the tail

Amino Acids as biomarkers in the SOD1G93A mouse model of ALS

AbstractThe development of therapies for Amyotrophic Lateral Sclerosis (ALS) has been hindered by the lack of biomarkers for both identifying early disease and for monitoring the effectiveness of drugs. The identification of ALS biomarkers in presymptomatic individuals might also provide clues to the earliest biochemical correlates of the disease. Previous attempts to use plasma metabolites as biomarkers have led to contradictory results, presumably because of heterogeneity in both the underlying genetics and the disease stage in the clinical population. To eliminate these two sources of heterogeneity we have characterized plasma amino acids and other metabolites in the SOD1G93A transgenic mouse model for ALS. Presymptomatic SOD1G93A mice have significant differences in concentrations of several plasma metabolites compared to wild type animals, most notably in the concentrations of aspartate, cystine/cysteine, and phosphoethanolamine, and in changes indicative of methylation defects. There are significant changes in amino acid compositions between 50 and 70days of age in both the SOD1G93A and wild type mice, and several of the age-related and disease-related differences in metabolite concentration were also gender-specific. Many of the SOD1G93A-related differences could be altered by treatment of mice with methionine sulfoximine, which extends the lifespan of this mouse, inhibits glutamine synthetase, and modifies brain methylation reactions. These studies show that assaying plasma metabolites can effectively distinguish transgenic mice from wild type, suggesting that one or more plasma metabolites might be useful biomarkers for the disease in humans, especially if genetic and longitudinal analysis is used to reduce population heterogeneity

Plasma properties of driver gas following interplanetary shocks observed by ISEE-3

Plasma fluid parameters calculated from solar wind and magnetic field data obtained on ISEE 3 were studied. The characteristic properties of driver gas following interplanetary shocks was determined. Of 54 shocks observed from August 1978 to February 1980, nine contained a well defined driver gas that was clearly identifiable by a discontinuous decrease in the average proton temperature across a tangential discontinuity. While helium enhancements were present in all of nine of these events, only about half of them contained simultaneous changes in the two quantities. Often the He/H ratio changed over a period of minutes. Simultaneous with the drop in proton temperature the helium and electron temperature decreased abruptly. In some cases the proton temperature depression was accompanied by a moderate increase in magnetic field magnitude with an unusually low variance and by an increase in the ratio of parallel to perpendicular temperature. The drive gas usually displayed a bidirectional flow of suprathermal solar wind electrons at higher energies

Structure of the low latitude boundary layer

Observations at high temporal resolution of the frontside magnetopause and plasma boundary layer, made with the LASL/MPE fast plasma analyzer onboard the ISEE 1 and 2 spacecraft, revealed a complex quasiperiodic structure of some of the observed boundary layers. A cool tailward streaming boundary layer plasma was seen intermittently, with intervening periods of hot tenuous plasma which has properties similar to the magnetospheric population. While individual encounters with the boundary layer plasma last only a few minutes, the total observation time may extend over one hour or more

Plasma behavior during energetic electron streaming events: Further evidence for substorm-associated magnetic reconnection

A recent study showed that streaming energetic (〉200 keV) electrons in Earth's magnetotail are statistically associated with southward magnetic fields and with enhancements of the AE index. It is shown here that the streaming electrons characteristically are preceded by a ∼15 minute period of tailward plasma flow and followed by a dropout of the plasma sheet, thus demonstrating a clear statistical association between substorms and the classical signatures of magnetic reconnection and plasmoid formation. Additionally, a brief upward surge of mean electron energy preceded plasma dropout in several of the events studied, providing direct evidence of localized, reconnection-associated heating processes