Francisco José Ayala, especialista en evolució i en filosofia de la biologia

Dins del XI Congrés Internacional d'Ontologia, Francisco José Ayala (Universitat de Califòrnia, Irvine) va oferir una xerrada sobre la biologia i la cultura humanes a la Facultat de Filosofia i Lletres el 6 d'octubre. Ayala ha desenvolupat tota la seva carrera acadèmica als Estats Units, tot esdevenint un dels científics més prestigiosos de l'actualitat.Dentro del XI Congreso Internacional de Ontología, Francisco José Ayala (Universidad de California, Irvine) ofreció una charla sobre la biología y la cultura humanas en la Facultad de Filosofía y Letras el 6 de octubre. Ayala ha desarrollado su carrera académica en Estados Unidos, convirtiéndose en uno de los científicos más prestigiosos de hoy en día.As part of the 11th International Conference on Ontology, Francisco José Ayala (University of California, Irvine) gave a talk on human biology and culture at the Faculty of Philosophy and Arts on 6 October. Ayala has carried out his entire academic career in the United States and is now one of the most prestigious scientists in the world

Fermiology and transport properties of the half-metallic itinerant ferromagnet CoS2_2: influence of spin orbit coupling

Electronic structure calculations were performed on the compound CoS$_2$, an itinerant ferromagnet whose magnetic properties can be understood in terms of spin fluctuation theory. We have identified nesting features in the Fermi surface of the compound, active for long wavelength spin fluctuations. The electronic structure of the material is close to a half-metal. We show the importance of introducing spin-orbit coupling (SOC) in the calculations, that partially destroys the half-metallicity of the material. By means of transport properties calculations, we have quantified the influence of SOC in the conductivity at room temperature, with an important decrease comparing to the GGA alone conductivity. SOC also helps to understand the negative 0 of the material, whose conductivity varies by a few percent with the introduction of small perturbations in the states around the Fermi level.Comment: 8 pages, 8 figure

Electronic structure analysis of the quasi-one-dimensional oxide Sr6Co5O15 within the LDA+U method

The quasi-one-dimensional cobalt oxide Sr6Co5O15 is studied using first-principles electronic-structure calculations and Boltzmann transport theory. We have been able to describe the electronic structure, characterized by the structural one-dimensionality and a particular type of charge ordering, with unexpected electronic structure of the different Co atoms. The origin of the large unquenched misaligned orbital angular momenta comes out naturally from a correct description of the different crystal-field environments. The evolution with the on-site Coulomb repulsion (U) of the electronic structure and the transport properties is discussed, with a best agreement with experiment found for the smallest value of U that allows to converge the correct in-chain ferrimagnetic ground state.Fil: Botana, A. S.. Universidad de Santiago de Compostela; EspañaFil: Botta, Pablo Martín. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Mar del Plata. Instituto de Investigación en Ciencia y Tecnología de Materiales (i); Argentina. Universidad Nacional de Mar del Plata. Facultad de Ingeniería; ArgentinaFil: De la Calle, C.. Instituto de Ciencia de Materiales de Madrid; EspañaFil: Piñeiro, A.. Universidad de Santiago de Compostela; EspañaFil: Pardo, V.. Universidad de Santiago de Compostela; EspañaFil: Botana, J.. Universidad de Santiago de Compostela; EspañaFil: Pereiro, M.. Universidad de Santiago de Compostela; EspañaFil: Baldomir, D.. Universidad de Santiago de Compostela; EspañaFil: Alonso, J. A.. Instituto de Ciencia de Materiales de Madrid; EspañaFil: Arias, J. E.. Universidad de Santiago de Compostela; Españ

Calculations of giant magnetoresistance in Fe/Cr trilayers using layer potentials determined from {\it ab-initio} methods

The ab initio full-potential linearized augmented plane-wave method explicitly designed for the slab geometry was employed to elucidate the physical origin of the layer potentials for the trilayers nFe/3Cr/nFe(001), where n is the number of Fe monolayers. The thickness of the transition-metal ferromagnet has been ranged from $n=1$ up to n=8 while the spacer thickness was fixed to 3 monolayers. The calculated potentials were inserted in the Fuchs-Sondheimer formalism in order to calculate the giant magnetoresistance (GMR) ratio. The predicted GMR ratio was compared with the experiment and the oscillatory behavior of the GMR as a function of the ferromagnetic layer thickness was discussed in the context of the layer potentials. The reported results confirm that the interface monolayers play a dominant role in the intrinsic GMR.Comment: 17 pages, 7 figures, 3 tables. accepted in J. Phys.: Cond. Matte

EL NUEVO RÉGIMEN APLICABLE A LA EMISIÓN DE OBLIGACIONES POR SOCIEDADES COOPERATIVAS

This paper makes reference to the securing of financiation included in the Co-operatives Act 27/1999, which in order to facilite business development in this business format empowers these societies to issue bonds. By virtue of the Act 5/2015,of Promotion of Business Financiation, the issuance of bonds by Co-operatives is governed by the rules of the XI Title of the Societies Capital Act, approved by RD-Legislative 1/2010,of 2 July.Este estudio hace referencia a la captación de recursos económicos que prevé la Ley 27/1999, de Cooperativas la cual, en aras de facilitar su propio desarrollo empresarial, autoriza a estas sociedades a emitir obligaciones. Por virtud de la Ley5/2015,de Fomento de la Financiación Empresarial, la emisión de obligaciones por las sociedades cooperativas ha pasado a regirse por las disposiciones del título XI de la Ley de Sociedades de Capital, aprobado por el Real Decreto-Legislativo1/2010, de 2 de julio

Computing bisectors in a dynamic geometry environment

In this note, an approach combining dynamic geometry and automated deduction techniques is used to study the bisectors between points and curves. Usual teacher constructions for bisectors are discussed, showing that inherent limitations in dynamic geometry software impede their thorough study. We show that the interactive sketching of bisectors and an automatic treatment of the algebraic problem involved can give a reasonable knowledge about them. Since some cases are currently out of computational scope, despite the simplicity of the bisector problem, we sketch an alternative method for dealing with them

Modificaciones de la microestructura y la capa pasiva de la aleación 2024-T3 Al-Cu durante una limpieza química empleada en la industria aeroespacial

Se han investigado los efectos de un pretratamiento superficial empleado en el sector aeroespa-cial sobre la aleación 2024-T3 Al-Cu antes de la generación de recubrimientos por conversión química. Estos pretratamientos influyen en las fases metálicas, que desempeñan un papel clave en el desarrollo de nuevos recu-brimientos de conversión sin cromo y en la susceptibilidad a la corrosión localizada en medios que contienen cloruros. El pretratamiento estudiado consta de dos etapas alcalinas y una ácida. La microscopía electrónica de barrido reveló que después del proceso completo, las fases Al(Cu,Mg) se eliminaban parcial o totalmente medi-ante desaleación y su posterior enriquecimiento de cobre, mientras que solo se atacó la matriz de aluminio que rodeaba las fases Al(Cu,Fe,Mn,Si). El análisis electroquímico reveló el viraje a catódico de las fases Al(Cu,Mg) que aún permanecen en la superficie mientras que la fases Al(Cu,Fe,Mn,Si) presentaron un mayor potencial de corrosión que la matriz de aluminio. Por el contrario, ninguna de estas fases se vio afectada cuando se emplearon únicamente las dos etapas alcalinas. Identificados los procesos que tienen lugar cuando la aleación es sometida a un pretratamiento superficial, es posible diseñar sistemas de protección alternativos a los cromatos.Changes in the microstructure and passive layer of 2024-T3 Al-Cu alloy during a chemical clean-ing employed in the aerospace industry. A standard surface pretreatment for 2024-T3 Al-Cu alloy prior to the generation of chemical conversion coatings in the aerospace sector have been investigated. These pretreatments influence the alloy phases, which play a key role in the development of new eco-friendly chromium-free conver-sion coatings, but also in the susceptibility to localized corrosion in chloride medium. The complete pretreat-ment consists of two alkaline step and another acid step. Scanning Electron Microscopy revealed that after the complete pretreatment, Al(Cu,Mg) phases were partially or totally removed through dealloying with their subsequent copper enrichment, while only the aluminum matrix surrounding the Al(Cu,Fe,Mn,Si) phases was slightly attacked. Electrochemical analysis revealed the turn to cathodic character of Al(Cu,Mg) phases that still remain on the surface, while the Al(Cu,Fe,Mn,Si) phases have a higher corrosion potential than the aluminum matrix. Conversely, none of these phases were affected when only alkaline steps were employed. Identified the corrosion processes that take place in the different phases when the alloy is treated with a surface pretreatment, it is possible to design alternative Cr-free protective proces