4,124 research outputs found

    Spin-orbit coupling, minimal model and potential Cooper-pairing from repulsion in BiS2_2-superconductors

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    We develop the realistic minimal electronic model for recently discovered BiS2_2 superconductors including the spin-orbit coupling based on a first-principles band structure calculations. Due to strong spin-orbit coupling, characteristic for the Bi-based systems, the tight-binding low-energy model necessarily includes pxp_x, pyp_y, and pzp_z orbitals. We analyze a potential Cooper-pairing instability from purely repulsive interaction for the moderate electronic correlations using the so-called leading angular harmonics approximation (LAHA). For small and intermediate doping concentrations we find the dominant instabilities to be dx2y2d_{x^2-y^2}-wave, and s±s_{\pm}-wave symmetries, respectively. At the same time, in the absence of the sizable spin fluctuations the intra and interband Coulomb repulsion are of the same strength, which yields the strongly anisotropic behaviour of the superconducting gaps on the Fermi surface in agreement with recent ARPES findings. In addition, we find that the Fermi surface topology for BiS2_2 layered systems at large electron doping can resembles the doped iron-based pnictide superconductors with electron and hole Fermi surfaces with sufficient nesting between them. This could provide further boost to increase TcT_c in these systems.Comment: 10 pages, 3 figure

    Variación de las características mecánicas de armaduras de alta ductilidad B500SD en función de su grado de corrosión / Mechanical properties variation of B500SD high ductility reinforcement regarding its corrosion degree

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    Los efectos de la corrosión sobre las armaduras se manifiestan por la pérdida de sección y la variación de las propiedades mecánicas relacionadas con la ductilidad. En este trabajo se han ensayado a tracción 96 barras de acero B500SD que previamente se han sometido a niveles variables de corrosión. Los resultados muestran que los alargamientos de las barras disminuyen y el cociente entre la tensión máxima y el límite elástico aumenta conforme el nivel de corrosión avanza. A partir del estudio del efecto de entalla y de la distinta constitución metalográfica del acero a nivel de sección debido a su procedimiento de fabricación se pueden explicar los fenómenos anteriores

    Stress-strain response and microstructural evolution of a FeMnCAl TWIP steel during tension-compression tests

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    © 2016. The stress-strain response of a Fe-17.5Mn-0.7C-2Al TWIP steel during cyclic loading has been investigated by means of tension-compression tests within the strain limits of ±2%, ±5% and ±10%. In addition, the microstructural evolution during the ±5% cyclic test has also been studied. The difference between the forward and reverse stress for each pre-strain has been analyzed at 0.2% offset strain and at the strains in which forward and reverse curves were parallel in order to study the Bauschinger effect (BE) and permanent softening, respectively. The evolution of the BE with pre-strain for this steel is similar to other FeMnC TWIP steels, that is, increasing values of BE are obtained as the pre-strain increases. However, its absolute values are half those reported in the literature on other FeMnC steels. This diminution of the BE is related to the lower activity of mechanical twinning in FeMnCAl TWIP steels at the pre-strains herein investigated, which promotes less polarized stresses in the matrix due to the lower dislocation storage capacity.Regarding permanent softening, the evolution is similar to that of the BE and the same analysis can be applied. During reverse compression, a slight increase of twin thickness and twin spacing with respect to the first tensile stage took place. This fact might be linked to the lower flow stress observed in the permanent softening period during reverse straining.Peer ReviewedPostprint (author's final draft

    On the validity of the 630 nm Fe I nm lines for the magnetometry of the internetwork quiet Sun

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    The purpose of this work is to analyze the reliability of the magnetic field strengths inferred from the 630 nm pair of Fe I lines at internetwork quiet Sun regions. Some numerical experiments have been performed that demonstrate the inability of these lines to recover the magnetic field strength in such low flux solar regions. It is shown how different model atmospheres, with magnetic field strengths ranging from few hundred Gauss to kiloGauss, give rise to Stokes profiles that can not be distinguished. The reasons for this degeneracy are discussed.Comment: Accepted for publication in A&

    Anisakis infection in allis shad, Alosa alosa (Linnaeus, 1758), and twaite shad, Alosa fallax (Lacépède, 1803), from Western Iberian Peninsula Rivers : zoonotic and ecological implications

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    Acknowledgments The authors would like to thank M. N. Cueto and J.M. Antonio (ECOBIOMAR) for their excellent technical support and also Rodrigo López for making the map of the study area. We also thank the personal of the Vigo IEO, for providing information about shad captures at sea collected on the basis of national program (AMDES) included in the European Data Collection Framework (DCF) project. We are also grateful to Comandancia Naval de Tui for providing fishing data. M. Bao is supported by a PhD grant from the University of Aberdeen and also by financial support of the contract from the EU Project PARASITE (grant number 312068). This study was partially supported by a PhD grant from the Portuguese Foundation for Science and Technology (FCT) SFRH/BD/44892/2008) and partially supported by the European Regional Development Fund (ERDF) through the COMPETE—Operational Competitiveness Programme and national funds through Foundation for Science and Technology (FCT), under the project BPEst-C/MAR/ LA0015/2013. The authors thank the staff of the Station of Hydrobiology of the USC BEncoro do Con^ due their participation in the surveys. This work has been partially supported by the project 10PXIB2111059PR of the Xunta de Galicia and the project MIGRANET of the Interreg IV BSUDOE (South-West Europe) Territorial Cooperation Programme (SOE2/P2/E288). D.J. Nachón is supported by a PhD grant from the Xunta de Galicia (PRE/2011/198)Peer reviewedPostprin

    Gender based prescriptions: evidence for altruism

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    This paper analyzes the way in which men and women are expected to behave differently in an experimental situation. To do so, we concentrate on a single topic: altruism. Since the dictator game provides the most suitable design for studying altruism and generosity in the lab setting, we use a modified version to study the beliefs involved in the game. Our results are substantial: men and women are expected to behave differently and both believe that women are more generous. These two premises affect their behavior.prescriptions, dictator game, beliefs, generosity, gender

    Gestión y optimización de los controles de proceso de envasado

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    En la industria farmacéutica un pequeño error puede tener grandes consecuencias, por ello se deben cumplir cuidadosamente las normas de calidad. En este estudio se ha querido plasmar una situación real que se da en la industria y su gestión correspondiente: la aparición de un problema de calidad, el estudio de la situación pertinente y la búsqueda de una solución. El enfoque implementado ha implicado la modificación de algunos procedimientos de control de proceso y el más importante, la formación e implicación del personal del departamento
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