Enhancing the Brightness of High Current Electron Guns

Concepts such as the two-beam accelerator offer the possibility of translating pulsed power technology into a form useful to the design of high luminosity accelerators for high-energy physics applications. Realization of the promise of these concepts will require the design of electron guns which are optimized with respect to beam brightness at current levels of approximately 1 kA. Because high luminosity implies accelerator operation at high repetition rates, the high-current beam source must be designed so that the beam does not intercept the electrodes. In our investigations of electron gun configurations, we have found that the brightness of a given source is set by practical design choices such as peak voltage, cathode type, gun electrode geometry, and focusing field topology. To investigate the sensitivity of beam brightness to these factors in a manner suitable for modelling transient phenomena at the beam head, we have developed a Darwin approximation particle code, DPC. The main component in our experimental program is a readily modified electron gun that allows us to test many candidate cathode materials, types, and electrode geometries at field stresses up to 1 MW/cm. We have also developed several diagnostics suitable for measuring the brightness of intense, low-emittance beams

Documentation of Subtype C HIV Type 1 Strains in Argentina, Paraguay and Uruguay.

HIV subtypes B, F, and BF recombinants have been previously reported in South America. This report describes the presence of HIV-1 subtype C infection in the countries of Argentina, Uruguay, and Paraguay dating back to at least 1999. Surveillance for uncommon non-B/non-F subtype viruses circulating in South America has been conducted in samples obtained from nine countries. Peripheral blood mononuclear cells (PBMC), dried filter paper (FP), and fresh blood (FB) samples were collected from HIV-positive patients from Ecuador, Colombia, Venezuela, Peru, Chile, Bolivia, Argentina, Uruguay, and Paraguay. From a total of 2962 HIV seropositive samples examined during a 9-year period (1995-2003), only 11 (0.4%) were found to be infected with non-B/non-F HIV variants. Eight of these 11 strains were determined to be subtype C by heteroduplex mobility assay (HMA). Five of these 8 strains were further characterized by sequencing and phylogenetic analysis of the protease (Pro) and reverse transcriptase (RT) region of the genome and two were sequenced full length. One of the strains was found to be a unique BC recombinant. The spread of a third subtype of HIV, subtype C, should raise the question of its potential future role in the HIV epidemic in this region.Fil: Carrion, G.. U.S. Naval Medical Research Center Detachment; PerúFil: Eyzaguirre, L.. Henry M. Jackson Foundation; Estados UnidosFil: Montano, S. M.. U.S. Naval Medical Research Center Detachment; PerúFil: Laguna Torres, V.. U.S. Naval Medical Research Center Detachment; PerúFil: Serra, M.. National AIDS Control Program; UruguayFil: Aguayo, N.. National AIDS Control Program; ParaguayFil: Avila, Maria Mercedes. National Reference for AIDS; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; ArgentinaFil: Ruchansky, D.. National Laboratory of Reference for HIV-AIDS; UruguayFil: Pando, María de los Ángeles. National Reference for AIDS; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; ArgentinaFil: Vinoles, Jose. National Laboratory of Reference for HIV-AIDS; UruguayFil: Perez, J.. U.S. Naval Medical Research Center Detachment; PerúFil: Barboza, A.. National AIDS Control Program; ParaguayFil: Chauca, G.. U.S. Naval Medical Research Center Detachment; PerúFil: Romero, A.. U.S. Naval Medical Research Center Detachment; PerúFil: Galeano, A.. Tropical Medicine Institute; ParaguayFil: Blair, P.J.. U.S. Naval Medical Research Center Detachment; PerúFil: Weissenbacher, Mercedes Crecencia. National Reference for AIDS; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; ArgentinaFil: Birx, D. L.. Walter Reed Army Institute of Research; Estados UnidosFil: Sanchez, J. L.. Walter Reed Army Institute of Research; Estados UnidosFil: Olson, J. G.. U.S. Naval Medical Research Center Detachment; PerúFil: Carr, J. K.. Henry M. Jackson Foundation; Estados Unido

Delayed-type hypersensitivity in classic Kaposi sarcoma patients and controls

BACKGROUND: Immune perturbation likely affects the development of Kaposi sarcoma (KS) among people infected with the KS-associated herpesvirus (KSHV). We tested whether KSHV-seropositive individuals or cases of classic KS (cKS), which typically originates in the leg, had differing delayed-type hypersensitivity (DTH) in the forearm or leg. METHODS: Mantoux DTH with three antigens (Candida, tetanus, PPD) was performed on the forearm and leg of 15 cKS cases, 14 KSHV-positives without KS, and 15 KSHV-negative controls. The diameters of induration responses were compared by group and body site. RESULTS: Leg DTH was greater than forearm DTH among controls (mean difference 5.6 mm, P\ubc0.0004), whereas this was not observed in cKS cases ( 2.2 mm, P\ubc0.32) or KSHV-positives (0.5 mm, P\ubc0.56). Leg-minus-forearm DTH difference was greater in controls compared with cKS cases (P\ubc0.004) and KSHV-positives (P\ubc0.002). Leg-plus-forearm DTH was similar in controls (mean 28.2 mm) and cKS cases (24.5 mm, P\ubc0.60), but it was reduced in KSHV-positives (11.8 mm, P\ubc0.02), particularly in the leg (P\ubc0.004) and marginally in the forearm (P\ubc0.07). CONCLUSION: KS cases had weaker DTH only in the leg, whereas both body sites appeared weaker in KSHV-positives without KS. Both systemic and regional immune alterations may influence the development of this malignancy

Exposure to Nonhuman Primates in Rural Cameroon

A high percentage of rural villagers are exposed to blood of nonhuman primates and risk acquiring infectious diseases

Beam dynamics in the ETA and ATA 10 kA linear induction accelerators: observations and issues

The 10 kA ETA and ATA linear induction accelerators are described. Beam instability is the major concern in these high current machines, and the current status of theoretical understanding, and experimental investigations with the 8 cavity ETA, are reviewed. Modifications to the induction cavities are described that have essentially eliminated the transverse resonant modes seen in the ETA