Nuevas perspectivas para la lengua española en Filipinas

El anuncio hecho por el Gobierno filipino sobre la reintroducción del español en la enseñanza secundaria ofrece unas nuevas perspectivas. La nueva situación merece una reflexión basada en los derechos individuales. El proyecto piloto del Departamento de Educación filipino significa que 17 escuelas públicas ofrecerán la asignatura optativa de español en secundaria. Esta oferta se suma a la de algunas escuelas privadas y universidades. España puede apoyar en formación de profesores, asesorías lingüísticas o aulas bilingües, como hace en otros países. Todo ello, sin olvidar la dimensión americana de la lengua y el derecho a elegir la enseñanza por parte de los interesados

Large scale ab-initio simulations of dislocations

We present a novel methodology to compute relaxed dislocations core configurations, and their energies in crystalline metallic materials using large-scale ab-intio simulations. The approach is based on MacroDFT, a coarse-grained density functional theory method that accurately computes the electronic structure with sub-linear scaling resulting in a tremendous reduction in cost. Due to its implementation in real-space, MacroDFT has the ability to harness petascale resources to study materials and alloys through accurate ab-initio calculations. Thus, the proposed methodology can be used to investigate dislocation cores and other defects where long range elastic effects play an important role, such as in dislocation cores, grain boundaries and near precipitates in crystalline materials. We demonstrate the method by computing the relaxed dislocation cores in prismatic dislocation loops and dislocation segments in magnesium (Mg). We also study the interaction energy with a line of Aluminum (Al) solutes. Our simulations elucidate the essential coupling between the quantum mechanical aspects of the dislocation core and the long range elastic fields that they generate. In particular, our quantum mechanical simulations are able to describe the logarithmic divergence of the energy in the far field as is known from classical elastic theory. In order to reach such scaling, the number of atoms in the simulation cell has to be exceedingly large, and cannot be achieved with the state-of-the-art density functional theory implementations

MXE: A package for simulating long-term diffusive mass transport phenomena in nanoscale systems

We present a package to simulate long-term diffusive mass transport in systems with atomic scale resolution. The implemented framework is based on a non-equilibrium statistical thermo-chemo-mechanical formulation of atomic systems where effective transport rates are computed using a kinematic diffusion law. Our implementation is built as an add-on to the Large-scale Atomic/Molecular Massively Parallel Simulator (LAMMPS) code, it is compatible with other LAMMPS’ functionalities, and shows a good parallel scalability and efficiency. In applications involving diffusive mass transport, this framework is able to simulate problems of technological interest for exceedingly large time scales using an atomistic description, which are not reachable with the state-of-the-art molecular dynamics techniques. Several examples, involving complex diffusive behavior in materials, are investigated with the framework. We found good qualitative and quantitative comparison with known theories and models, with Monte Carlo methods, as well as with experimental results. Thus, our implementation can be used as a tool to understand diffusive behavior in materials where experimental characterization is difficult to perform

Coupled thermoelastic simulation of nanovoid cavitation by dislocation emission at finite temperature

In this work we study the early onset of void growth by dislocation emission at finite temperature in single crystal of copper under uniaxial loading conditions using the HotQC method. The results provide a detailed characterization of the cavitation mechanism, including the geometry of the emitted dislocations, the dislocation reaction paths and attendant macroscopic quantities of interest such as the cavitation pressure. In addition, this work shows that as prismatic dislocation loops grow and move away from the void, the material surrounded by these loops is pushed away from the void surface, giving rise to a flux of material together with a heat flux through the crystal

Diffusive molecular dynamics simulations of lithiation of silicon nanopillars

We report diffusive molecular dynamics simulations concerned with the lithiation of Si nano-pillars, i. e., nano-sized Si rods held at both ends by rigid supports. The duration of the lithiation process is of the order of miliseconds, well outside the range of molecular dynamics but readily accessible to diffusive molecular dynamics. The simulations predict an alloy Li_(15)Si_4 at the fully lithiated phase, exceedingly large and transient volume increments up to 300% due to the weakening of Si-Si iterations, a crystalline-to-amorphous-to-lithiation phase transition governed by interface kinetics, high misfit strains and residual stresses resulting in surface cracks and severe structural degradation in the form of extensive porosity, among other effects

Proliferation of twinning in hexagonal close-packed metals: Application to magnesium

Plastic deformation of metallic alloys usually takes place through slip, but occasionally involves twinning. In particular, twinning is important in hexagonal close packed (HCP) materials where the easy slip systems are insufficient to accommodate arbitrary deformations. While deformation by slip mechanisms is reasonably well understood, comparatively less is known about deformation by twinning. Indeed, the identification of relevant twinning modes remains an art. In this paper, we develop a framework combining a fundamental kinematic definition of twins with large-scale atomistic calculations to predict twinning modes of crystalline materials. We apply this framework to magnesium where there are two accepted twin modes, tension and compression, but a number of anomalous observations. Remarkably, our framework shows that there is a very large number of twinning modes that are important in magnesium. Thus, in contrast to the traditional view that plastic deformation is kinematically partitioned between a few modes, our results suggest that deformation in HCP materials is the result of an energetic and kinetic competition between numerous possibilities. Consequently, our findings suggest that the commonly used models of deformation need to be extended in order to take into account a broader and richer variety of twin modes, which, in turn, opens up new avenues for improving the mechanical properties

Cría y manejo del cachorro del lobo ibérico (Canis lupus signatus)

El lobo ibérico (Canis lupus signatus) es un cánido salvaje bien representado en parques zoológicos en cautividad. Este trabajo expone los protocolos de actuación para un correcto manejo del neonato de lobo durante la lactancia artificial, así como para el destete y su medicina preventiva (vacunación y desparasitación). También se tendrá en cuenta las influencias del factor humano en su desarrollo y las patologías más frecuentes que se pueden presentar en el lobo ibérico en esta edad. Para este trabajo se emplearon diferentes tetinas dependiendo de la edad de los animales. Se utilizaron leches artificiales de cánido doméstico durante el tiempo de lactancia y carne de diferente origen para su destete. Las vacunas usadas para llevar a cabo el protocolo de medicina preventiva propuesto fueron vacunas comerciales de cánidos domésticos. Los cachorros de este trabajo adquirieron tras seis meses las características fisiológicas en cuanto a peso, tamaño, etc. esperadas. Los protocolos propuestos en este trabajo son considerados válidos para la crianza del cachorro del lobo ibérico en cautividad.The Iberian wolf (Canis lupus signatus)is a wild animal well represented in zoological parks. This work exposes the performance protocols for a correct managing of the newborn of wolf during the artificial lactation, as well as for wean and his preventive medicine (vaccination and worm). Also take into account the influences of the human factor in their development and the most frequent pathologies than can be presented in the Iberian wolf in this age. In this work we employ different teat, depending on the age on the animals. We used artificial milk of domestic dog during the lactation and meat of different origin for there wean. The vaccines used to carry out the proposed preventive medicine protocol were commercial vaccines of domestic dog. The cubs of this work acquired, after six months, the physiological characteristics; weight, size, etc. waited. The protocols proposed in this work were considered valid for the breed of the cub of Iberian wolf in zoological parks