13,969 research outputs found
Nonextensive Interpretation Of Radiative Recombination In Electron Cooling
An interest for the low-energy range of the nonextensive distribution
function arises from the study of radiative recombination in electron cooling
devices in particle accelerators, whose experimentally measured reaction rates
are much above the theoretical prediction. The use of generalized
distributions, that differ from the Maxwellian in the low energy part (due to
subdiffusion between electron and ion bunches), may account for the observed
rate enhancement. In this work, we consider the isotropic distribution function
and we propose a possible experiment for verifying the existence of a cut-off
in the generalized momentum distribution, by measuring the spectrum of the
X-rays emitted from radiative recombination reactions.Comment: 8 pages, 2 figures, Submitted for publication in the Proceedings of
the 3rd International Conference NEXT-SigmaPhi, 2005, Cret
Reduction of Lie--Jordan algebras: Quantum
In this paper we present a theory of reduction of quantum systems in the
presence of symmetries and constraints. The language used is that of
Lie--Jordan Banach algebras, which are discussed in some detail together with
spectrum properties and the space of states. The reduced Lie--Jordan Banach
algebra is characterized together with the Dirac states on the physical algebra
of observables
Status of TOTEM
The status of the TOTEM experiment is described as well as the prospects for the measurements in the 2010 runs. The primary goal of TOTEM is the measurement of the total p-p cross section, using a method independent of the
luminosity. A final accuracy of 1% is expected with dedicated β∗ = 1540m runs (5% resolution with β∗ = 90m, more easily achievable in the early runs). TOTEM has installed the T2 telescope and fully equipped Roman Pots in the 220m stations during the last winter shutdown and is taking the first p-p collision data with these detectors. T1 is finalizing the commissioning on beam and will be ready for the first opportunity of installation. During 2010 the collaboration will carry on a full commissioning of all detectors and will start a physics program compatible with the low β∗ optics provided by the machine
How to enhance crop production and nitrogen fluxes? A result-oriented scheme to evaluate best agri-environmental measures in Veneto Region, Italy
The cost-effectiveness of adopting agri-environmental measures (AEMs) in Europe, which combine agricultural productions with reduced N losses, is debated due to poorly targeted site-specific funding that is allocated regardless of local variability. An integrated DAYCENT model-GIS platform was developed combining pedo-climatic and agricultural systems information. The aim was to evaluate best strategies to improve N fluxes of agro-ecosystems within a perspective of sustainable intensification. Indicators of agronomic efficiency and environmental quality were considered. The results showed that agronomic benefits were observed with a continuous soil cover (conservation agriculture and cover crops), which enhanced nitrogen use efficiency (+17%) and crop yields (+34%), although in some cases these might be overestimated due to modelling limitations. An overall environmental improvement was found with continuous soil cover and long-term change from mineral to organic inputs (NLeach 45 Mg ha 121), which were effective in the sandy soils of western and eastern Veneto with low SOM, improving the soil-water balance and nutrients availability over time. Results suggest that AEM subsidies should be allocated at a site-specific level that includes pedo-climatic variability, following a result-oriented approach
Reduced lysosomal acid lipase activity: A new marker of liver disease severity across the clinical continuum of non-alcoholic fatty liver disease?
Lysosomal acid lipase (LAL) plays a key role in intracellular lipid metabolism. Reduced LAL activity promotes increased multi-organ lysosomal cholesterol ester storage, as observed in two recessive autosomal genetic diseases, Wolman disease and Cholesterol ester storage disease. Severe liver steatosis and accelerated liver fibrosis are common features in patients with genetic LAL deficiency. By contrast, few reliable data are available on the modulation of LAL activity in vivo and on the epigenetic and metabolic factors capable of regulating its activity in subjects without homozygous mutations of the Lipase A gene. In the last few years, a less severe and non-genetic reduction of LAL activity was reported in children and adults with non-alcoholic fatty liver disease (NAFLD), suggesting a possible role of LAL reduction in the pathogenesis and progression of the disease. Patients with NAFLD show a significant, progressive reduction of LAL activity from simple steatosis to non-alcoholic steatohepatitis and cryptogenic cirrhosis. Among cirrhosis of different etiologies, those with cryptogenic cirrhosis show the most significant reductions of LAL activity. These findings suggest that the modulation of LAL activity may become a possible new therapeutic target for patients with more advanced forms of NAFLD. Moreover, the measurement of LAL activity may represent a possible new marker of disease severity in this clinical setting
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