54 research outputs found
Fernando SEBASTIÁN AGUILAR, Nueva Evangelización. Fe, cultura y política en la España de hoy, Ed. Encuentro, Madrid 1991, 302 pp. [RECENSIÓN]
\u3cp\u3eThe most recent JET campaign has focused on characterizing operation with the «ITER-like» wall. One of the questions that needed to be answered is whether the auxiliary heating methods do not lead to unacceptably high levels of impurity influx, preventing fusion-relevant operation. In view of its high single pass absorption, hydrogen minority fundamental cyclotron heating in a deuterium plasma was chosen as the reference wave heating scheme in the ion cyclotron domain of frequencies. The present paper discusses the plasma behavior as a function of the minority concentration X[H] in L-mode with up to 4MW of RF power. It was found that the tungsten concentration decreases by a factor of 4 when the minority concentration is increased from X[H] ≈ 5% to X[H] % 20% and that it remains at a similar level when X[H] is further increased to 30%; a monotonic decrease in Beryllium emission is simultaneously observed. The radiated power drops by a factor of 2 and reaches a minimum at X[H] ≈ 20%. It is discussed that poor single pass absorption at too high minority concentrations ultimately tailors the avoidance of the RF induced impurity influx. The edge density being different for different minority concentrations, it is argued that the impact ICRH has on the fate of heavy ions is not only a result of core (wave and transport) physics but also of edge dynamics and fueling.\u3c/p\u3
Oxidative stress and immunologic responses following a dietary exposure to PAHs in Mya arenaria
<p>Abstract</p> <p>Background</p> <p>The aim of this research was to investigate oxidative stress and immune responses following a dietary polycyclic aromatic hydrocarbon (PAH) exposure in a marine bioindicator organism, the soft shell clam, <it>Mya arenaria</it>. Immune parameters in hemolymph (haemocyte number, efficiency of phagocytosis and haemocyte activity) and assessment of oxidative stress using catalase (CAT) activity and levels of malondialdehyde (MDA) performed on the digestive gland were estimated as biomarkers in clams fed in mesocosm with PAH contaminated phytoplankton. MDA levels and CAT activities were also measured <it>in situ </it>in organisms sampled in a control site (Metis Beach, Québec, Canada) as well as organisms sampled in a site receiving domestic effluents (Pointe-au-Père, Québec, Canada), to assess effects of abiotic variables related to seasonal variations and mixed contamination on the selected parameters.</p> <p>Results</p> <p>Results on immune parameters suggest that the PAHs may interfere with the maturation and/or differentiation processes of haemocytes. MDA results showed that lipid peroxidation did not occur following the exposure. The levels of CAT activity corresponded to weak antioxidant activity (no significant differences). Recovery was noted for all the immune endpoints at the end of the experiment.</p> <p>Conclusion</p> <p>Results suggest that immune parameters are early biomarkers that can efficiently detect a physiological change during a short term exposure to low concentrations of PAHs. The <it>in situ </it>survey (in the natural environment) suggested that clams from the Pointe-au-Père site did not show any oxidative stress as well as the clams contaminated in mesocosm, probably due to the low concentrations of PAHs used for this study. MDA levels increased however in organisms from Metis Beach, a response probably related to domestic effluents or parasitism.</p
Sporadic amyotrophic lateral sclerosis: new hypothesis regarding its etiology and pathogenesis suggests that astrocytes might be the primary target hosting a still unknown external agent
Ethics, Risk and Benefits Associated with Different Applications of Nanotechnology: a Comparison of Expert and Consumer Perceptions of Drivers of Societal Acceptance
New bolometry cameras for the JET enhanced performance phase
Two new bolometer cameras, for horizontal and vertical views of the plasma cross-section, are under construction for the Enhanced Performance Phase of JET, to begin in 2005. These cameras replace previous cameras in operation and represent a substantial upgrade in capabilities: more viewing chords over a larger viewing angle, higher detectable energy range, higher sensitivity, lower noise level and therefore, lower detectable signal (similar to 1 mu W/cm(2) for tau = 2 ms versus similar to 70 mu W/cm(2) for tau = 20 ms). The detectors are essentially the same as those in use on ASDEX-Upgrade (gold energy-absorbing layer, mica substrate, gold meander), whereby the absorber layer has been increased in thickness from 4 to 8 mu m in order to extend sensitivity to 8 keV. Each camera is comprised of 24 channels, with a particularly fine spatial resolution in the divertor region of similar to 8 cm. Definition of the lines-of-sight is attained by a collimator arrangement for the vertical camera and use of pinholes for the horizontal camera. Salient design features of these cameras are described. (c) 2005 Elsevier B.V. All rights reserved
First beam waist measurements in the final focus beam line at the KEK Accelerator Test Facility
The ATF2 project is the final focus system prototype for the ILC and CLIC linear collider projects, with a purpose to reach a 37 nm vertical beam size at the interaction point using compact optics based on a novel scheme of local chromaticity correction. Construction of all components and installation were completed at the end of 2008. An initial commissioning phase followed in 2009, using larger than nominal beta functions at the interaction point, corresponding to reduced demagnification factors in comparison to the design, to limit effects from higher-order optical aberrations and hence simplify beam tuning procedures while key instrumentation was being tested and calibrated. In this paper, first measurements of dispersion and Twiss parameters are presented based on scanning the beam during this period with a set of tungsten wires located just behind the interaction point, using two complementary analysis methods
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