3,365 research outputs found
Erosion y productividad en la comarca lagunera
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
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
We develop the idea of manipulating the scattering length 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 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 . 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 Li.Comment: 12 pages, 1 Postscript figur
Disorder-induced trapping versus Anderson localization in Bose-Einstein condensates expanding in disordered potentials
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
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
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
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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Calibration of the charge and energy loss per unit length of the MicroBooNE liquid argon time projection chamber using muons and protons
We describe a method used to calibrate the position- and time-dependent response of the MicroBooNE liquid argon time projection chamber anode wires to ionization particle energy loss. The method makes use of crossing cosmic-ray muons to partially correct anode wire signals for multiple effects as a function of time and position, including cross-connected TPC wires, space charge effects, electron attachment to impurities, diffusion, and recombination. The overall energy scale is then determined using fully-contained beam-induced muons originating and stopping in the active region of the detector. Using this method, we obtain an absolute energy scale uncertainty of 2% in data. We use stopping protons to further refine the relation between the measured charge and the energy loss for highly-ionizing particles. This data-driven detector calibration improves both the measurement of total deposited energy and particle identification based on energy loss per unit length as a function of residual range. As an example, the proton selection efficiency is increased by 2% after detector calibration
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Reconstruction and measurement of (100) MeV energy electromagnetic activity from π0 arrow γγ decays in the MicroBooNE LArTPC
We present results on the reconstruction of electromagnetic (EM) activity from photons produced in charged current νμ interactions with final state π0s. We employ a fully-automated reconstruction chain capable of identifying EM showers of (100) MeV energy, relying on a combination of traditional reconstruction techniques together with novel machine-learning approaches. These studies demonstrate good energy resolution, and good agreement between data and simulation, relying on the reconstructed invariant π0 mass and other photon distributions for validation. The reconstruction techniques developed are applied to a selection of νμ + Ar → μ + π0 + X candidate events to demonstrate the potential for calorimetric separation of photons from electrons and reconstruction of π0 kinematics
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