Many-body fermionic excitations in Weyl semimetals due to elastic gauge fields

We study the single-particle spectrum of three-dimensional Weyl semimetals taking into account electron-phonon interactions that are the result of straining the material. We find that a well-defined fermionic excitation appears in addition to the standard peak corresponding to quasiparticle states as suggested by Landau-Fermi liquid theory. Contrary to the case of Dirac systems interacting via the Coulomb interaction, these satellite peaks appear even at lowest order in perturbation theory. The new excitations are anisotropic, as opposed to the single-particle spectrum, and their behavior is dictated by the Debye frequency, which naturally regulates the electron-phonon coupling.Comment: 10 pages, 2 figures, 5 pages supplemental materia

Identificació d'evidències en el marc de les ciències per al món contemporani

La nova matèria Ciències per la Món Contemporani té com a objectiu principal afavorir que l’alumnat de batxillerat adquireixi les competències necessàries per comprendre el món actual, tant des de la perspectiva social com científica. Per tal d’assolir aquests objectius un dels propòsits és que l’alumnat comprengui la manera de treballar dels científics. La nostra recerca està centrada en l’estudi de les dificultats de l’alumnat per identificar i interpretar evidències a partir de la lectura de textos i gràfics. Els primers resultats indiquen dificultats importants per part de l’alumnat per identificar evidències dels marcs teòrics estudiats durant l’ESO, per distingir evidències de valors ètics i d’opinions personals. En el cas dels gràfics s’observem dificultats en l’aplicació d’habilitats cognitives com descriure i interpretar per identificar evidències

Effects of a perceptual-motor program in response reaction to older people

Diversos trabajos han mostrado que se puede reducir el tiempo de reacción en los mayores con la práctica de actividad física (Hunter et al., 2001) e incluso igualar al de los jóvenes (Light et al., 1996). 52 hombres y mujeres de la ciudad de Melilla distribuidos en dos grupos de estudio: un grupo control (n=26 ; M= 68,56 años) que participa en actividades físicas genéricas y un grupo experimental (n=26 ; M=67,32 años) que ha participado en las mismas actividades más un programa de entrenamiento específico para la mejora del equilibrio, ajuste postural y tiempo de reacción. Los resultados no muestran diferencias significativas en el postest ni en la prueba de transferencia, pero los sujetos del grupo experimental alcanzan mejores desempeños en las dos variables de estudio (Tiempo de reacción simple - TRs y tiempo de inicio del movimiento - TIm) (GE TRs M= .55 ; TIm M=. 53 ; GC TRs M=.60 ; TIm M=. 64). Por subgrupos de estudio, las mujeres del subgrupo 60-70 años participantes en el programa obtuvieron resultados significativamente mejores que el resto de subgrupos consideradosAccording to several studies, physical activity can reduce the reaction time of elderly people (Hunter et al., 2001) and even make it equal to that of young people (Light et al., 1996). This project included 52 men and women from the City of Melilla distributed in two groups of study: a Control Group (n=26; M=68, 56 years old) taking part in generic physical activities, and an Experimental Group (n=26; M=67, 32 years) undertaking these same activities and also a specific training programme designed to improve balance, postural adjustment and reaction time. The results do not show significant differences either in the post-test or in the transfer test. However, the subjects from the experimental group achieved better performances on the two study variables (simple reaction time or sRT and initial movement time iMT) (EG sRT M=.55; iMT M=.53; CG sRT M=.60; iMT M=.64). In the per-subgroup analysis, the women of the 60-70-years-old subgroup who participated in the programme obtained significant better results than the subjects of the other subgroups

La reputación regional como el diferencial de precio : estimación de un modelo hedónico de precios para los vinos de Castilla-La Mancha

Wine is a multi-attribute product and one of great differentiation. Consumers do not know wines’ intrinsic properties before its purchase; consumers need and look for extrinsic signals that allow them to infer those intrinsic properties. To evaluate those intrinsic wine properties, the article uses price as an extrinsic signal to express their value. The price used is a comparison between the prices suggested by the specialized guides and the ones proposed directly to the consumer at the on-line stores. With the hedonic price methodology, which relates price and attributes, the article shows the convergence between the value referenced (price) by the Spanish experts and the one paid (price) in the Spanish market, the former being independent of the interests of the economic agents and the latter not. Regional reputation is the only attribute that positively impacts the price of Castilian wine and is prioritized in the ranking of attributes.El vino es un producto de atributos múltiples y de gran diferenciación. Los consumidores no conocen las propiedades intrínsecas de los vinos antes de su compra; los consumidores necesitan y buscan señales extrínsecas que les permitan inferir esas propiedades intrínsecas. Para evaluar esas propiedades intrínsecas del vino, este artículo usa el precio como una señal extrínseca para expresar su valor. El precio utilizado es una comparación entre los precios sugeridos por las guías especializadas y los que se proponen directamente al consumidor en las tiendas en línea. Con la metodología de precios hedónicos, que relaciona precios y atributos, este artículo muestra la convergencia entre el valor referenciado (precio) por los expertos españoles y el valor pagado (precio) en el mercado español, siendo el primero independiente de los intereses de los agentes económicos y el último no. La reputación regional es el único atributo que impacta positivamente en el precio del vino castellano y se prioriza en el ranking de atributos al momento de compra.Fil: Castillo-Valero, Sebastián. Universidad de Castilla-La ManchaFil: Villanueva, Emiliano C.. Eastern Connecticut State UniversityFil: García-Cortijo, M. Carmen. Universidad de Castilla-La Manch

Electronic properties of curved graphene sheets

A model is proposed to study the electronic structure of slightly curved graphene sheets with an arbitrary number of pentagon-heptagon pairs and Stone-Wales defects based on a cosmological analogy. The disorder induced by curvature produces characteristic patterns in the local density of states that can be observed in scanning tunnel and transmission electron microscopy.Comment: Corrected versio

La reputación regional como el diferencial de precio: estimación de un modelo hedónico de precios para los vinos de Castilla-La Mancha

Wine is a multi-attribute product and one of great differentiation. Consumers do not know wines’ intrinsic properties before its purchase; consumers need and look for extrinsic signals that allow them to infer those intrinsic properties. To evaluate those intrinsic wine properties, the article uses price as an extrinsic signal to express their value. The price used is a comparison between the prices suggested by the specialized guides and the ones proposed directly to the consumer at the on-line stores. With the hedonic price methodology, which relates price and attributes, the article shows the convergence between the value referenced (price) by the Spanish experts and the one paid (price) in the Spanish market, the former being independent of the interests of the economic agents and the latter not. Regional reputation is the only attribute that positively impacts the price of Castilian wine and is prioritized in the ranking of attributes.El vino es un producto de atributos múltiples y de gran diferenciación. Los consumidores no conocen las propiedades intrínsecas de los vinos antes de su compra; los consumidores necesitan y buscan señales extrínsecas que les permitan inferir esas propiedades intrínsecas. Para evaluar esas propiedades intrínsecas del vino, este artículo usa el precio como una señal extrínseca para expresar su valor. El precio utilizado es una comparación entre los precios sugeridos por las guías especializadas y los que se proponen directamente al consumidor en las tiendas en línea. Con la metodología de precios hedónicos, que relaciona precios y atributos, este artículo muestra la convergencia entre el valor referenciado (precio) por los expertos españoles y el valor pagado (precio) en el mercado español, siendo el primero independiente de los intereses de los agentes económicos y el último no. La reputación regional es el único atributo que impacta positivamente en el precio del vino castellano y se prioriza en el ranking de atributos al momento de compra

Predicting grower choices in a regulated environment

The analysis of farmers’ decision making process in the framework of agricultural policy is particularly complex as they take action within a structure of interacting opportunities, preferences, benefits and social factors which ultimately account for their behavior. This paper will study viticulturists’ behaviour vis-à-vis this scenario. Their decisions in the face of different possible alternatives are analysed using a multinomial logit model and a sample of 74,502 plots in Castilla-La Mancha (Spain). The conclusion is that viticulturists from this region are more prone to maintaining the status quo in their plots due to the current public support security issues, uncertain scenarios and their natural risk aversion

Revivals of quantum wave-packets in graphene

We investigate the propagation of wave-packets on graphene in a perpendicular magnetic field and the appearance of collapses and revivals in the time-evolution of an initially localised wave-packet. The wave-packet evolution in graphene differs drastically from the one in an electron gas and shows a rich revival structure similar to the dynamics of highly excited Rydberg states. We present a novel numerical wave-packet propagation scheme in order to solve the effective single-particle Dirac-Hamiltonian of graphene and show how the collapse and revival dynamics is affected by the presence of disorder. Our effective numerical method is of general interest for the solution of the Dirac equation in the presence of potentials and magnetic fields.Comment: 22 pages, 10 figures, 3 movies, to appear in New Journal of Physic

The spatially-resolved star formation histories of CALIFA galaxies: Implications for galaxy formation

This paper presents the spatially resolved star formation history (SFH) of nearby galaxies with the aim of furthering our understanding of the different processes involved in the formation and evolution of galaxies. To this end, we apply the fossil record method of stellar population synthesis to a rich and diverse data set of 436 galaxies observed with integral field spectroscopy in the CALIFA survey. The sample covers a wide range of Hubble types, with stellar masses ranging from $M_\star \sim 10^9$ to $7 \times 10^{11} M_\odot$. Spectral synthesis techniques are applied to the datacubes to retrieve the spatially resolved time evolution of the star formation rate (SFR), its intensity ($\Sigma_{\rm SFR}$), and other descriptors of the 2D-SFH in seven bins of galaxy morphology (E, S0, Sa, Sb, Sbc, Sc, and Sd), and five bins of stellar mass. Our main results are: a) Galaxies form very fast independently of their current stellar mass, with the peak of star formation at high redshift ($z > 2$). Subsequent star formation is driven by $M_\star$ and morphology, with less massive and later type spirals showing more prolonged periods of star formation. b) At any epoch in the past the SFR is proportional to $M_\star$, with most massive galaxies having the highest absolute (but lowest specific) SFRs. c) While nowadays $\Sigma_{\rm SFR}$ is similar for all spirals, and significantly lower in early type galaxies (ETG), in the past $\Sigma_{\rm SFR}$ scales well with morphology. The central regions of today's ETGs are where $\Sigma_{\rm SFR}$ reached the highest values ($> 10^3 \,M_\odot\,$Gyr$^{-1}\,$pc$^{-2}$), similar to those measured in high redshift star forming galaxies. d) The evolution of $\Sigma_{\rm SFR}$ in Sbc systems matches that of models for Milky-Way-like galaxies, suggesting that the formation of a thick disk may be a common phase in spirals at early epochs.Comment: 21 pages, 11 figures, 1 table, accepted for publication in Astronomy & Astrophysics, abstract abridged for arXiv submissio