282 research outputs found

    Fractal superconductivity near localization threshold

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    We develop a semi-quantitative theory of electron pairing and resulting superconductivity in bulk "poor conductors" in which Fermi energy EFE_F is located in the region of localized states not so far from the Anderson mobility edge EcE_c. We review the existing theories and experimental data and argue that a large class of disordered films is described by this model. Our theoretical analysis is based on the analytical treatment of pairing correlations, described in the basis of the exact single-particle eigenstates of the 3D Anderson model, which we combine with numerical data on eigenfunction correlations. Fractal nature of critical wavefunction's correlations is shown to be crucial for the physics of these systems. We identify three distinct phases: 'critical' superconductive state formed at EF=EcE_F=E_c, superconducting state with a strong pseudogap, realized due to pairing of weakly localized electrons and insulating state realized at EFE_F still deeper inside localized band. The 'critical' superconducting phase is characterized by the enhancement of the transition temperature with respect to BCS result, by the inhomogeneous spatial distribution of superconductive order parameter and local density of states. The major new feature of the pseudo-gaped state is the presence of two independent energy scales: superconducting gap Δ\Delta, that is due to many-body correlations and a new "pseudogap" energy scale ΔP\Delta_P which characterizes typical binding energy of localized electron pairs and leads to the insulating behavior of the resistivity as a function of temperature above superconductive TcT_c. Two gap nature of the "pseudo-gaped superconductor" is shown to lead to a number of unusual physical properties.Comment: 110 pages, 39 figures. The revised version corrects a number of typos, adds references and discussion of recent result

    Efficacy of menthol as an anesthetic for tambaqui (Colossoma macropomum, Characiformes: Characidae)

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    Anesthetics are important in fish culture to reduce handling stress and mortality. The objective of this work is to investigate menthol as an anesthetic for tambaqui. In the first series of tests, fish were exposed to various concentrations of menthol to evaluate induction time and stress responses. The second series examined the effect of exposure period to menthol at 150 mg/L on recovery time. The third assessed the best dosage for juveniles in larger tambaqui. The best concentration for surgical anesthesia is 150 mg/L. At this concentration the induction time is short, but their recovery time is significantly longer than that for lower concentrations. For biometry procedures, the best concentration is 100 mg/L. At this concentration the induction time is prolonged, but the recovery time is within the desired period. Recovery time for fish exposed to 150 mg/L is equal for 10, 20 or 30 minutes of exposure. The results confirmed that menthol is an adequate anesthetic for tambaqui.Os anestĂ©sicos sĂŁo importantes na piscicultura para reduzir o estresse e a mortalidade no manejo. Este trabalho tem como objetivo determinar a eficĂĄcia do mentol para tambaqui durante o manejo. Na primeira sĂ©rie de testes, foi examinado o efeito da concentração de anestĂ©sico sobre indução Ă  anestesia e o estresse de tambaqui. Na segunda sĂ©rie de testes, foi avaliada a recuperação dos peixes apĂłs a exposição a uma concentração de 150 mg/L de mentol por diferentes tempos. Na terceira sĂ©rie, foi avaliada se a melhor concentração encontrada para juvenil (150 mg/L) tambĂ©m era adequada para peixes maiores. A melhor concentração para uma anestesia cirĂșrgica foi 150 mg/L, pois o tempo de indução Ă© rĂĄpido, porĂ©m a recuperação Ă© significativamente mais demorada do que para as menores concentraçÔes testadas. Para uma anestesia, com finalidade de biometria, a melhor concentração foi 100 mg/L. Nesta concentração o tempo de indução Ă  anestesia Ă© prolongado, porĂ©m o tempo de recuperação estĂĄ dentro da faixa considerada adequada. O tempo de recuperação do tambaqui quando exposto a 150 mg/L Ă© significativamente igual para 10, 20 e 30 minutos de anestesia. Os resultados obtidos mostram que o mentol Ă© um anestĂ©sico eficiente para o tambaqui

    Search for direct production of charginos and neutralinos in events with three leptons and missing transverse momentum in √s = 7 TeV pp collisions with the ATLAS detector

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    A search for the direct production of charginos and neutralinos in final states with three electrons or muons and missing transverse momentum is presented. The analysis is based on 4.7 fb−1 of proton–proton collision data delivered by the Large Hadron Collider and recorded with the ATLAS detector. Observations are consistent with Standard Model expectations in three signal regions that are either depleted or enriched in Z-boson decays. Upper limits at 95% confidence level are set in R-parity conserving phenomenological minimal supersymmetric models and in simplified models, significantly extending previous results

    Jet size dependence of single jet suppression in lead-lead collisions at sqrt(s(NN)) = 2.76 TeV with the ATLAS detector at the LHC

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    Measurements of inclusive jet suppression in heavy ion collisions at the LHC provide direct sensitivity to the physics of jet quenching. In a sample of lead-lead collisions at sqrt(s) = 2.76 TeV corresponding to an integrated luminosity of approximately 7 inverse microbarns, ATLAS has measured jets with a calorimeter over the pseudorapidity interval |eta| < 2.1 and over the transverse momentum range 38 < pT < 210 GeV. Jets were reconstructed using the anti-kt algorithm with values for the distance parameter that determines the nominal jet radius of R = 0.2, 0.3, 0.4 and 0.5. The centrality dependence of the jet yield is characterized by the jet "central-to-peripheral ratio," Rcp. Jet production is found to be suppressed by approximately a factor of two in the 10% most central collisions relative to peripheral collisions. Rcp varies smoothly with centrality as characterized by the number of participating nucleons. The observed suppression is only weakly dependent on jet radius and transverse momentum. These results provide the first direct measurement of inclusive jet suppression in heavy ion collisions and complement previous measurements of dijet transverse energy imbalance at the LHC.Comment: 15 pages plus author list (30 pages total), 8 figures, 2 tables, submitted to Physics Letters B. All figures including auxiliary figures are available at http://atlas.web.cern.ch/Atlas/GROUPS/PHYSICS/PAPERS/HION-2011-02
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