923 research outputs found

    Effect of q-deformation in the NJL gap equation

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    We obtain a q-deformed algebra version of the Nambu-Jona-Lasinio model gap equation. In this framework we discuss some hadronic properties such as the dynamical mass generated for the quarks, the pion decay constant and the phase transition present in this model.Comment: 5 pages, 1 eps figure, to appear in Phys. Lett. B 448 (1999) 1-

    Lasso Estimation of an Interval-Valued Multiple Regression Model

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    A multiple interval-valued linear regression model considering all the cross-relationships between the mids and spreads of the intervals has been introduced recently. A least-squares estimation of the regression parameters has been carried out by transforming a quadratic optimization problem with inequality constraints into a linear complementary problem and using Lemke's algorithm to solve it. Due to the irrelevance of certain cross-relationships, an alternative estimation process, the LASSO (Least Absolut Shrinkage and Selection Operator), is developed. A comparative study showing the differences between the proposed estimators is provided

    mu-Theraphotoxin-An1a: primary structure determination and assessment of the pharmacological activity of a promiscuous anti-insect toxin from the venom of the tarantula Acanthoscurria natalensis (Mygalomorphae, Theraphosidae)

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    Tarantulas are included in the mygalomorph spider family Theraphosidae. Although the pharmacological diversity of theraphosid toxins (theraphotoxins) is broad, studies dedicated to the characterization of biologically active molecules from the theraphosid genus Acanthoscurria have been restricted to the investigation of antimicrobial peptides and polyamines produced by the hemocytes of Acanthoscurria gomesiana. The present study reports the purification, primary structure determination and electrophysiological effects of an anti-insect toxin, named mu-theraphotoxin-An1a (mu-TRTX-An1a), from the venom of Acanthoscurria natalensis - a tarantula species occurring in the Brazilian biomes caatinga and cerrado. The analysis of the primary structure of mu-TRTX-An1a revealed the similarity of this toxin to theraphosid toxins bearing a huwentoxin-II-like fold. Electrophysiological experiments showed that mu-TRTX-An1a (100 nM) induces membrane depolarization, increases the spontaneous firing frequency and reduces spike amplitude of cockroach dorsal unpaired median (DUM) neurons. In addition, under voltage-clamp conditions, mu-TRTX-An1a (100 nM) only partially blocks voltage-dependent sodium current amplitudes in DUM neurons without any effect on their voltage dependence. This effect correlates well with the reduction of the spontaneous action potential amplitudes. Altogether, these last results suggest that mu-TRTX-An1a affects insect neuronal voltage-dependent sodium channels, which are among possible channels targeted by this promiscuous toxin

    Cosmic coincidence problem and variable constants of physics

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    The standard model of cosmology is investigated using time dependent cosmological constant Λ\Lambda and Newton's gravitational constant GG. The total energy content is described by the modified Chaplygin gas equation of state. It is found that the time dependent constants coupled with the modified Chaplygin gas interpolate between the earlier matter to the later dark energy dominated phase of the universe. We also achieve a convergence of parameter ω1\omega\to-1, with minute fluctuations, showing an evolving ω\omega. Thus our model fairly alleviates the cosmic coincidence problem which demands ω=1\omega=-1 at present time.Comment: 27 pages, 15 figure

    The generalized second law for the interacting generalized Chaplygin gas model

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    We investigate the validity of the generalized second law (GSL) of gravitational thermodynamics in a non-flat FRW universe containing the interacting generalized Chaplygin gas with the baryonic matter. The dynamical apparent horizon is assumed to be the boundary of the universe. We show that for the interacting generalized Chaplygin gas as a unified candidate for dark matter (DM) and dark energy (DE), the equation of state parameter can cross the phantom divide. We also present that for the selected model under thermal equilibrium with the Hawking radiation, the GSL is always satisfied throughout the history of the universe for any spatial curvature, independently of the equation of state of the interacting generalized Chaplygin gas model.Comment: 8 page

    Theory and Applications of Non-Relativistic and Relativistic Turbulent Reconnection

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    Realistic astrophysical environments are turbulent due to the extremely high Reynolds numbers. Therefore, the theories of reconnection intended for describing astrophysical reconnection should not ignore the effects of turbulence on magnetic reconnection. Turbulence is known to change the nature of many physical processes dramatically and in this review we claim that magnetic reconnection is not an exception. We stress that not only astrophysical turbulence is ubiquitous, but also magnetic reconnection itself induces turbulence. Thus turbulence must be accounted for in any realistic astrophysical reconnection setup. We argue that due to the similarities of MHD turbulence in relativistic and non-relativistic cases the theory of magnetic reconnection developed for the non-relativistic case can be extended to the relativistic case and we provide numerical simulations that support this conjecture. We also provide quantitative comparisons of the theoretical predictions and results of numerical experiments, including the situations when turbulent reconnection is self-driven, i.e. the turbulence in the system is generated by the reconnection process itself. We show how turbulent reconnection entails the violation of magnetic flux freezing, the conclusion that has really far reaching consequences for many realistically turbulent astrophysical environments. In addition, we consider observational testing of turbulent reconnection as well as numerous implications of the theory. The former includes the Sun and solar wind reconnection, while the latter include the process of reconnection diffusion induced by turbulent reconnection, the acceleration of energetic particles, bursts of turbulent reconnection related to black hole sources as well as gamma ray bursts. Finally, we explain why turbulent reconnection cannot be explained by turbulent resistivity or derived through the mean field approach.Comment: 66 pages, 24 figures, a chapter of the book "Magnetic Reconnection - Concepts and Applications", editors W. Gonzalez, E. N. Parke

    Magnetic Field Amplification in Galaxy Clusters and its Simulation

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    We review the present theoretical and numerical understanding of magnetic field amplification in cosmic large-scale structure, on length scales of galaxy clusters and beyond. Structure formation drives compression and turbulence, which amplify tiny magnetic seed fields to the microGauss values that are observed in the intracluster medium. This process is intimately connected to the properties of turbulence and the microphysics of the intra-cluster medium. Additional roles are played by merger induced shocks that sweep through the intra-cluster medium and motions induced by sloshing cool cores. The accurate simulation of magnetic field amplification in clusters still poses a serious challenge for simulations of cosmological structure formation. We review the current literature on cosmological simulations that include magnetic fields and outline theoretical as well as numerical challenges.Comment: 60 pages, 19 Figure

    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

    Modelagem tridimensional de uma escola “sustentável”: avaliação bioclimática do edifício

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    CIES2020 - XVII Congresso Ibérico e XIII Congresso Ibero-americano de Energia SolarRESUMO: A arquitetura contemporânea apesar de publicizar a sustentabilidade, foca o desempenho ambiental e não busca tratar a sustentabilidade holisticamente. O artigo tem como objetivo investigar a qualidade bioclimática de edifício escolar situado no litoral brasileiro (cidade de Recife-PE), que publiciza promover a sustentabilidade através do edifício. Para odesenvolvimento da pesquisa foi realizado o percurso metodológico: Coleta documental e pesquisa bibliográficado colégio; Visita ao colégio; Aprofundamento teórico sobre qualidade ambiental e arquitetura bioclimática; Análise bioclimática do colégio. O edifício foi projetado com o intuito de apresentar um bom desempenho sobre o ponto de vista ambiental, no entanto deixa a desejar quanto ao quesito consumo de energia. Constatou-se que a sustentabilidade do edifício parece ser uma estratégia de publicidade e de busca pela qualidade ambiental, do que a efetiva promoção da sustentabilidade a partir da visão holística.ABSTRACT: Contemporary architecture despite the sustainability of advertising, seal or environmental performance and does not seek to treat sustainability holistically. The article fears to investigate the bioclimatic quality of a school building located on the Brazilian coast (city of Recife-PE), which announces promoting sustainability through the building. For or development of the research carried out or methodological process: Queue of documents and bibliographic research of the school; Visit or school; Theoretical foundations of environmental quality and bioclimatic architecture; Bioclimatic analysis of the school. Or the building was designed as a way to perform in terms of the environmental point of view, I did not want to discard any amount of energy consumption. It appears that the building's sustainability appears to be an advertising strategy and search for environmental quality, in order to effectively promote sustainability from a holistic point of view.info:eu-repo/semantics/publishedVersio

    Measurement of D*+/- meson production in jets from pp collisions at sqrt(s) = 7 TeV with the ATLAS detector

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    This paper reports a measurement of D*+/- meson production in jets from proton-proton collisions at a center-of-mass energy of sqrt(s) = 7 TeV at the CERN Large Hadron Collider. The measurement is based on a data sample recorded with the ATLAS detector with an integrated luminosity of 0.30 pb^-1 for jets with transverse momentum between 25 and 70 GeV in the pseudorapidity range |eta| < 2.5. D*+/- mesons found in jets are fully reconstructed in the decay chain: D*+ -> D0pi+, D0 -> K-pi+, and its charge conjugate. The production rate is found to be N(D*+/-)/N(jet) = 0.025 +/- 0.001(stat.) +/- 0.004(syst.) for D*+/- mesons that carry a fraction z of the jet momentum in the range 0.3 < z < 1. Monte Carlo predictions fail to describe the data at small values of z, and this is most marked at low jet transverse momentum.Comment: 10 pages plus author list (22 pages total), 5 figures, 1 table, matches published version in Physical Review
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