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Plasma antioxidant status can be evaluated by selenium, retinol and a-tocopherol. The present study concerns 89 HIV-1 positive patients. The plasma level of selenium was determined by PIXE (proton-induced X-ray emission analysis) and by measurement of levels of vitamins A and E by HPLC. The data were compared to controls; among the HIV-1 patients, significant differences were found for plasma selenium between groups selected on the basis of the CD4 lymphocyte count. Differences were also observed for plasma retinol between the HIV-1 patients and the control subjects. Correlations with other nutritional and immunological parameters were shown.

Some of the problems associated with the monitoring of accelerator beams, particularly storage rings’ beams, are reviewed along with their most common solutions. The various electrode structures used for the measurement of beam current, beam position, and the detection of the bunches’ transverse oscillations, yield pulses with sub-nanosecond widths. The electronics for the processing of these short pulses involves wide band techniques and circuits usually not readily available from industry or the integrated circuit market: Passive or active, successive integrations, linear gating, sample-and-hold circuits with nanosecond acquisition time, etc. This report also presents the work performed recently for monitoring the ultrashort beams of colliding linear accelerators or single-pass colliders. To minimize the beam emittance, the beam position must be measured with a high resolution, and digitized on a pulse-to-pulse basis. Experimental results obtained with the Stanford two-mile Linac single bunches are included.