209 research outputs found

    Drought evolution in the NW Iberian Peninsula over a 60 year period (1960–2020)

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    Financiado para publicación en acceso aberto: Universidade de Vigo/CISUGDroughts affect the environment, the economy, and society causing socioeconomic problems derived from water scarcity, and actions are therefore required to mitigate them. To efficiently manage water resources, and prevent and mitigate the consequences of water scarcity, it is important to identify and characterize drought events. A study of the evolution of drought episodes over Galicia (NW Iberian Peninsula) from 1960 to 2020 was conducted based on data from several rain gauges in the region. The standardized precipitation index (SPI) at different time scales was used to characterize drought conditions. The results revealed an increase in the number of periods under drought conditions and the intensity of drought events towards the end of the period analyzed. The events tended to become longer over time, with a clear increase in the worst drought conditions.Xunta de Galicia | Ref. ED431C 2021/44Fundação para a Ciência e a Tecnologia | Ref. UIDP/50017/2020Fundação para a Ciência e a Tecnologia | Ref. UIDB/50017/2020Fundação para a Ciência e a Tecnologia | Ref. LA/P/0094/202

    Dynamic Front Transitions and Spiral-Vortex Nucleation

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    This is a study of front dynamics in reaction diffusion systems near Nonequilibrium Ising-Bloch bifurcations. We find that the relation between front velocity and perturbative factors, such as external fields and curvature, is typically multivalued. This unusual form allows small perturbations to induce dynamic transitions between counter-propagating fronts and nucleate spiral vortices. We use these findings to propose explanations for a few numerical and experimental observations including spiral breakup driven by advective fields, and spot splitting

    TP97 299. Experiencia en el uso de válvula aórtica biológica freedom solo en endocarditis

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    IntroducciónLas válvulas aórticas biológicas sin soporte Sorin Freedom Solo (FS) han demostrado una mejoría en el aumento del orificio de área efectivo, así como un mejor perfil en los gradientes transvalvulares, fracción de eyección del ventrículo izquierdo (FEVI) y regresión de la hipertrofia ventricular izquierda. También, se ha comprobado una reducción en los tiempos de isquemia miocárdica y de circulación extracorpórea. Sin embargo no hay mucha información sobre su comportamiento en el contexto de endocarditis valvular.Material y métodosDesde noviembre de 2006 – septiembre 2011, se implantaron 17 prótesis FS en 16 pacientes (50% hombres, 60,2±15 años) por endocarditis bacteriana. Se determinó la cantidad de plaquetas en el día 5 postimplante, así como la fracción de eyección (FE) y los gradientes transvalvulares posquirúrgicos. Seguimiento medio de 22,5±26 meses.ResultadosLa prevalencia de trombocitopenia (< 150.000 plaquetas) y trombocitopenia grave (< 50.000 plaquetas) ha sido de 68,8 y 31,3%, respectivamente. Hubo un total de 4 muertes hospitalarias (25%), 2 intraoperatorias. Gradiente transvalvular medio de 22±18mmHg, FEVI postoperatoria media de 52,4±10,3%. Tres pacientes fueron reintervenidos, 2 por deterioro precoz (16%), 1 por nueva endocarditis (8%).ConclusiónLa prótesis aórtica biológica sin soporte FS muestra un buen perfil hemodinámico, mejorando significati-vamente los gradientes transvalvulares.Nuestra prevalencia de trombocitopenia al quinto día y durabilidad de la válvula se encuentran en valores similares a lo publicado en la literatura.El uso de dicha prótesis en endocarditis aórtica debe considerarse una alternativa eficaz al demostrarse baja tasa de reincidencia de endocarditis

    An improved method for measuring muon energy using the truncated mean of dE/dx

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    The measurement of muon energy is critical for many analyses in large Cherenkov detectors, particularly those that involve separating extraterrestrial neutrinos from the atmospheric neutrino background. Muon energy has traditionally been determined by measuring the specific energy loss (dE/dx) along the muon's path and relating the dE/dx to the muon energy. Because high-energy muons (E_mu > 1 TeV) lose energy randomly, the spread in dE/dx values is quite large, leading to a typical energy resolution of 0.29 in log10(E_mu) for a muon observed over a 1 km path length in the IceCube detector. In this paper, we present an improved method that uses a truncated mean and other techniques to determine the muon energy. The muon track is divided into separate segments with individual dE/dx values. The elimination of segments with the highest dE/dx results in an overall dE/dx that is more closely correlated to the muon energy. This method results in an energy resolution of 0.22 in log10(E_mu), which gives a 26% improvement. This technique is applicable to any large water or ice detector and potentially to large scintillator or liquid argon detectors.Comment: 12 pages, 16 figure

    All-particle cosmic ray energy spectrum measured with 26 IceTop stations

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    We report on a measurement of the cosmic ray energy spectrum with the IceTop air shower array, the surface component of the IceCube Neutrino Observatory at the South Pole. The data used in this analysis were taken between June and October, 2007, with 26 surface stations operational at that time, corresponding to about one third of the final array. The fiducial area used in this analysis was 0.122 km^2. The analysis investigated the energy spectrum from 1 to 100 PeV measured for three different zenith angle ranges between 0{\deg} and 46{\deg}. Because of the isotropy of cosmic rays in this energy range the spectra from all zenith angle intervals have to agree. The cosmic-ray energy spectrum was determined under different assumptions on the primary mass composition. Good agreement of spectra in the three zenith angle ranges was found for the assumption of pure proton and a simple two-component model. For zenith angles {\theta} < 30{\deg}, where the mass dependence is smallest, the knee in the cosmic ray energy spectrum was observed between 3.5 and 4.32 PeV, depending on composition assumption. Spectral indices above the knee range from -3.08 to -3.11 depending on primary mass composition assumption. Moreover, an indication of a flattening of the spectrum above 22 PeV were observed.Comment: 38 pages, 17 figure

    Measurement of the polarisation of W bosons produced with large transverse momentum in pp collisions at sqrt(s) = 7 TeV with the ATLAS experiment

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    This paper describes an analysis of the angular distribution of W->enu and W->munu decays, using data from pp collisions at sqrt(s) = 7 TeV recorded with the ATLAS detector at the LHC in 2010, corresponding to an integrated luminosity of about 35 pb^-1. Using the decay lepton transverse momentum and the missing transverse energy, the W decay angular distribution projected onto the transverse plane is obtained and analysed in terms of helicity fractions f0, fL and fR over two ranges of W transverse momentum (ptw): 35 < ptw < 50 GeV and ptw > 50 GeV. Good agreement is found with theoretical predictions. For ptw > 50 GeV, the values of f0 and fL-fR, averaged over charge and lepton flavour, are measured to be : f0 = 0.127 +/- 0.030 +/- 0.108 and fL-fR = 0.252 +/- 0.017 +/- 0.030, where the first uncertainties are statistical, and the second include all systematic effects.Comment: 19 pages plus author list (34 pages total), 9 figures, 11 tables, revised author list, matches European Journal of Physics C versio

    Observation of a new chi_b state in radiative transitions to Upsilon(1S) and Upsilon(2S) at ATLAS

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    The chi_b(nP) quarkonium states are produced in proton-proton collisions at the Large Hadron Collider (LHC) at sqrt(s) = 7 TeV and recorded by the ATLAS detector. Using a data sample corresponding to an integrated luminosity of 4.4 fb^-1, these states are reconstructed through their radiative decays to Upsilon(1S,2S) with Upsilon->mu+mu-. In addition to the mass peaks corresponding to the decay modes chi_b(1P,2P)->Upsilon(1S)gamma, a new structure centered at a mass of 10.530+/-0.005 (stat.)+/-0.009 (syst.) GeV is also observed, in both the Upsilon(1S)gamma and Upsilon(2S)gamma decay modes. This is interpreted as the chi_b(3P) system.Comment: 5 pages plus author list (18 pages total), 2 figures, 1 table, corrected author list, matches final version in Physical Review Letter

    Search for displaced vertices arising from decays of new heavy particles in 7 TeV pp collisions at ATLAS

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    We present the results of a search for new, heavy particles that decay at a significant distance from their production point into a final state containing charged hadrons in association with a high-momentum muon. The search is conducted in a pp-collision data sample with a center-of-mass energy of 7 TeV and an integrated luminosity of 33 pb^-1 collected in 2010 by the ATLAS detector operating at the Large Hadron Collider. Production of such particles is expected in various scenarios of physics beyond the standard model. We observe no signal and place limits on the production cross-section of supersymmetric particles in an R-parity-violating scenario as a function of the neutralino lifetime. Limits are presented for different squark and neutralino masses, enabling extension of the limits to a variety of other models.Comment: 8 pages plus author list (20 pages total), 8 figures, 1 table, final version to appear in Physics Letters

    Measurement of the inclusive isolated prompt photon cross-section in pp collisions at sqrt(s)= 7 TeV using 35 pb-1 of ATLAS data

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    A measurement of the differential cross-section for the inclusive production of isolated prompt photons in pp collisions at a center-of-mass energy sqrt(s) = 7 TeV is presented. The measurement covers the pseudorapidity ranges |eta|<1.37 and 1.52<=|eta|<2.37 in the transverse energy range 45<=E_T<400GeV. The results are based on an integrated luminosity of 35 pb-1, collected with the ATLAS detector at the LHC. The yields of the signal photons are measured using a data-driven technique, based on the observed distribution of the hadronic energy in a narrow cone around the photon candidate and the photon selection criteria. The results are compared with next-to-leading order perturbative QCD calculations and found to be in good agreement over four orders of magnitude in cross-section.Comment: 7 pages plus author list (18 pages total), 2 figures, 4 tables, final version published in Physics Letters
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