282 research outputs found
Fractal superconductivity near localization threshold
We develop a semi-quantitative theory of electron pairing and resulting
superconductivity in bulk "poor conductors" in which Fermi energy is
located in the region of localized states not so far from the Anderson mobility
edge . 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
, superconducting state with a strong pseudogap, realized due to
pairing of weakly localized electrons and insulating state realized at
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 , that is due to many-body correlations and a new
"pseudogap" energy scale 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 . 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)
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 âs = 7 TeV pp collisions with the ATLAS detector
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 fbâ1 of protonâproton 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
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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