El Centro Europeo de Predicción a Medio Plazo

El Centro Europeo de Predicción a Medio Plazo es puntero a nivel mundial en la predicción numérica, y su estrategia de futuro apuesta decididamente por la predicción probabilista. Nos proponemos contar en qué consiste este organismo, quiénes lo integran, cómo se trabaja allí (y dónde es allí) y qué se hace. Qué son el IFS, el HRES, el ENS, y por qué son tan reconocidos en el mundo de la predicción meteorológica. Cómo funciona el sistema de predicción por conjuntos del Centro Europeo y por qué la estrategia del centro se vuelca en un ambicioso desarrollo de dicho sistema. Cuál es la participación española en la institución. La «brecha de género» que aqueja al mundo científico en general y meteorológico en particular, ¿se refleja también en un organismo tan prestigioso como éste? Y, como el propio presidente del organismo, lo resumimos todo en dos palabras: «Más colaboración»

Orbital magnetic susceptibility of graphene and MoS2

We calculate the orbital magnetic susceptibility χorb for an 8-band tight-binding model of gapless and gapped graphene using Green's functions. Analogously, we study χorb for a MoS2 12-band model. For both materials, we unravel the character of the processes involved in the magnetic response by looking at the contribution at each point of the Brillouin zone. By this, a clear distinction between intra- and interband excitations is generally possible and we are able to predict qualitative features of χorb only through the knowledge of the band structure. The study is complemented by comparing the magnetic response with that of 2-band lattice Hamiltonians which reduce to the Dirac and Bernevig-Hughes-Zhang models in the continuum limitThis work has been supported by Spain’s MINECO under Grants No. FIS2012-37549-C05-03, No. FIS2013-48048-P, and No. FIS2014-57432-P, and by the Communidad Madrid under Grant No. S2013/MIT-3007 MAD2D-C

Novel effects of strains in graphene and other two dimensional materials

The analysis of the electronic properties of strained or lattice deformed graphene combines ideas from classical condensed matter physics, soft matter, and geometrical aspects of quantum field theory (QFT) in curved spaces. Recent theoretical and experimental work shows the influence of strains in many properties of graphene not considered before, such as electronic transport, spin-orbit coupling, the formation of Moir\'e patterns, optics, ... There is also significant evidence of anharmonic effects, which can modify the structural properties of graphene. These phenomena are not restricted to graphene, and they are being intensively studied in other two dimensional materials, such as the metallic dichalcogenides. We review here recent developments related to the role of strains in the structural and electronic properties of graphene and other two dimensional compounds.Comment: 75 pages, 15 figures, review articl

Author Correction: Infuence of the surface viscous stress on the pinch‑of of free surfaces loaded with nearly‑inviscid surfactants [Corrección]

Correction to: Scientifc Reports https://doi.org/10.1038/s41598-020-73007-1, published online 30 September 2020. The original version of this Article contained errors

Multiwavelength optical observations of chromospherically active binary systems - II. EZ Pegasi

The star EZ Peg, long ago classified as cataclysmic variable, has been shown to be a chromospherically active binary system of the RS CVn-type. In this paper we have analysed, using the spectral subtraction technique, simultaneous spectroscopic observations of the Hα, Hβ, Na I D_1 and D_2, He I D_3, Mg I b triplet, Ca II H & K, and Ca II infrared triplet lines. We have found that the hot component is the active star of the system, showing strong emission in the Hα, Ca Ir H & K, Hε, and Ca II IRT lines, and a strong filling-in of the Hβ line, however the Na I D_1 and D_2 and Mg I b triplet lines do not present filled-in. The He I D_3 could present a total filling-in due to microflaring. The observed variations (in different epochs and with the orbital phase) of the different activity indicators, formed at different height in the chromosphere, are correlated. Very broad wings have been found in the subtracted profiles of Hα and Ca II IRT λ8498 and λ8662 lines. These profiles are well matched using a two-component Gaussian fit (narrow and broad) and the broad component could be interpreted as arising from microflaring. The higher luminosity class of the hot component, that our spectra seem to indicate, could explain why the hot component is the active star of the system

A hybrid approach to classification with shapelets

Shapelets are phase independent subseries that can be used to discriminate between time series. Shapelets have proved to be very effective primitives for time series classification. The two most prominent shapelet based classification algorithms are the shapelet transform (ST) and learned shapelets (LS). One significant difference between these approaches is that ST is data driven, whereas LS searches the entire shapelet space through stochastic gradient descent. The weakness of the former is that full enumeration of possible shapelets is very time consuming. The problem with the latter is that it is very dependent on the initialisation of the shapelets. We propose hybridising the two approaches through a pipeline that includes a time constrained data driven shapelet search which is then passed to a neural network architecture of learned shapelets for tuning. The tuned shapelets are extracted and formed into a transform, which is then classified with a rotation forest. We show that this hybrid approach is significantly better than either approach in isolation, and that the resulting classifier is not significantly worse than a full shapelet search

Cuando la segunda generación no se queda atrás: evidencias sobre el rendimiento académico de los hijos de inmigrantes en el caso andaluz

En este artículo se profundiza en la situación académica de los hijos de inmigrantes en España y, especialmente, en Andalucía. Con datos de PISA, se analizan estadísticamente la distancia con respecto a los estudiantes de origen nativo y el efecto que sobre la misma tienen diversas variables de interés. Los resultados confirman la sabida desventaja acadé- mica general de estos estudiantes, pero destacan un importante matiz menos difundido: los de “segunda generación” y quienes provienen de “parejas mixtas” puntúan al nivel de los nativos. El mayor nivel educativo de sus padres y el más elevado nivel sociocultural de sus hogares contribuyen a ello significativamente.This paper contributes to the knowledge about the academic attainment of children of immigrants in Spain and, specifically, in Andalusia. By using data from PISA, it is analyzed both the gap between immigrant and native students, and the effect that several variables of interest produce on such gap. Results confirm the already known academic disadvan- tage of immigrant students, but they also reveal an aspect that has been scarcely spread: second generation pupils and those coming from mixed parental couples perform as well as their native peers do. Higher educational level of their parents and higher household socio-cultural level contribute significantly to their outcomes