3,365 research outputs found

    Erosion y productividad en la comarca lagunera

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    Le présent travail a pour finalité l'étude de l'érosion dans la Région Hydrologique 36 en relation avec les conditions physico-climatiques qui la caractérisent. En première approche et avec l'objectif de préciser et affiner la méthode d'analyse proposée, la situation dans la "Comarca Lagunera" est prise comme exemple. Cette méthode est basée sur l'application de "l'Equation Universelle de Perte en Sol" et l'utilisation d'un Système d'Information Géographique. Il apparaît que l'érosivité climatique (R) se répartit spatialement suivant un gradient très net alors que le facteur de susceptibilité des sols à l'érosion (K) ne présente pas d'organisation bien marquée. Par ailleurs, l'étude montre que l'érosion est quantifiable sur 50,1 % de l'aire analysée, parmi lesquels 4,2 % correspondent à une érosion sévère, 11,8 % à une érosion modérée et 34,1 % à une érosion modérée à faible. Bien que l'on constate que l'érosion hydrique dans la "Comarca Lagunera" reste relativement peu importante, la simulation de séries temporelles sur 500 ans montre que si les taux actuels d'érosion se maintiennent constants, à court terme le rendement des cultures de maïs (prises comme exemple) sera sérieusemenet affecté par la dégradation de la productivité des sols. (Résumé d'auteur

    PIE: an online prediction system for protein–protein interactions from text

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    Protein–protein interaction (PPI) extraction has been an important research topic in bio-text mining area, since the PPI information is critical for understanding biological processes. However, there are very few open systems available on the Web and most of the systems focus on keyword searching based on predefined PPIs. PIE (Protein Interaction information Extraction system) is a configurable Web service to extract PPIs from literature, including user-provided papers as well as PubMed articles. After providing abstracts or papers, the prediction results are displayed in an easily readable form with essential, yet compact features. The PIE interface supports more features such as PDF file extraction, PubMed search tool and network communication, which are useful for biologists and bio-system developers. The PIE system utilizes natural language processing techniques and machine learning methodologies to predict PPI sentences, which results in high precision performance for Web users. PIE is freely available at http://bi.snu.ac.kr/pie/

    Influence of nearly resonant light on the scattering length in low-temperature atomic gases

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    We develop the idea of manipulating the scattering length aa in low-temperature atomic gases by using nearly resonant light. As found, if the incident light is close to resonance with one of the bound pp levels of electronically excited molecule, then virtual radiative transitions of a pair of interacting atoms to this level can significantly change the value and even reverse the sign of aa. The decay of the gas due to photon recoil, resulting from the scattering of light by single atoms, and due to photoassociation can be minimized by selecting the frequency detuning and the Rabi frequency. Our calculations show the feasibility of optical manipulations of trapped Bose condensates through a light-induced change in the mean field interaction between atoms, which is illustrated for 7^7Li.Comment: 12 pages, 1 Postscript figur

    Disorder-induced trapping versus Anderson localization in Bose-Einstein condensates expanding in disordered potentials

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    We theoretically investigate the localization of an expanding Bose-Einstein condensate with repulsive atom-atom interactions in a disordered potential. We focus on the regime where the initial inter-atomic interactions dominate over the kinetic energy and the disorder. At equilibrium in a trapping potential and for small disorder, the condensate shows a Thomas-Fermi shape modified by the disorder. When the condensate is released from the trap, a strong suppression of the expansion is obtained in contrast to the situation in a periodic potential with similar characteristics. This effect crucially depends on both the momentum distribution of the expanding BEC and the strength of the disorder. For strong disorder, the suppression of the expansion results from the fragmentation of the core of the condensate and from classical reflections from large modulations of the disordered potential in the tails of the condensate. We identify the corresponding disorder-induced trapping scenario for which large atom-atom interactions and strong reflections from single modulations of the disordered potential play central roles. For weak disorder, the suppression of the expansion signals the onset of Anderson localization, which is due to multiple scattering from the modulations of the disordered potential. We compute analytically the localized density profile of the condensate and show that the localization crucially depends on the correlation function of the disorder. In particular, for speckle potentials the long-range correlations induce an effective mobility edge in 1D finite systems. Numerical calculations performed in the mean-field approximation support our analysis for both strong and weak disorder.Comment: New Journal of Physics; focus issue "Quantum Correlations in Tailored Matter - Common perspectives of mesoscopic systems and quantum gases"; 30 pages, 10 figure

    Disordered ultracold atomic gases in optical lattices: A case study of Fermi-Bose mixtures

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    We present a review of properties of ultracold atomic Fermi-Bose mixtures in inhomogeneous and random optical lattices. In the strong interacting limit and at very low temperatures, fermions form, together with bosons or bosonic holes, {\it composite fermions}. Composite fermions behave as a spinless interacting Fermi gas, and in the presence of local disorder they interact via random couplings and feel effective random local potential. This opens a wide variety of possibilities of realizing various kinds of ultracold quantum disordered systems. In this paper we review these possibilities, discuss the accessible quantum disordered phases, and methods for their detection. The discussed quantum phases include Fermi glasses, quantum spin glasses, "dirty" superfluids, disordered metallic phases, and phases involving quantum percolation.Comment: 29 pages and 11 figure

    Inspiratory Muscle and Functional Performance of Patients Entering Cardiac Rehabilitation after Cardiac Valve Replacement

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    Limited research has examined inspiratory muscle performance (IMP) and functional performance (FP) of patients after valve replacement surgery (VRS). The purpose of this study was to examine IMP as well as several measures of FP in patients post-VRS. The study results of 27 patients revealed that patients undergoing transcatheter VRS were significantly (p = 0.01) older than patients undergoing minimally invasive or median sternotomy VRS with the median sternotomy VRS group performing significantly (p < 0.05) better than the transcatheter VRS group in the 6-min walk test, 5x sit-to-stand test, and sustained maximal inspiratory pressure. The 6-min walk test and IMP measures in all groups were significantly (p < 0.001) lower than predicted values. Significant (p < 0.05) relationships were found between IMP and FP with greater IMP being associated with greater FP. Pre-operative and early post-operative rehabilitation may improve IMP and FP post-VRS

    Precision measurement of the neutrino velocity with the ICARUS detector in the CNGS beam

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    During May 2012, the CERN-CNGS neutrino beam has been operated for two weeks for a total of 1.8 10^17 pot in bunched mode, with a 3 ns narrow width proton beam bunches, separated by 100 ns. This tightly bunched beam structure allows a very accurate time of flight measurement of neutrinos from CERN to LNGS on an event-by-event basis. Both the ICARUS-T600 PMT-DAQ and the CERN-LNGS timing synchronization have been substantially improved for this campaign, taking ad-vantage of additional independent GPS receivers, both at CERN and LNGS as well as of the deployment of the "White Rabbit" protocol both at CERN and LNGS. The ICARUS-T600 detector has collected 25 beam-associated events; the corresponding time of flight has been accurately evaluated, using all different time synchronization paths. The measured neutrino time of flight is compatible with the arrival of all events with speed equivalent to the one of light: the difference between the expected value based on the speed of light and the measured value is tof_c - tof_nu = (0.10 \pm 0.67stat. \pm 2.39syst.) ns. This result is in agreement with the value previously reported by the ICARUS collaboration, tof_c - tof_nu = (0.3 \pm 4.9stat. \pm 9.0syst.) ns, but with improved statistical and systematic errors.Comment: 21 pages, 13 figures, 1 tabl
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