Impurities and electronic localization in graphene bilayers

We analyze the electronic properties of bilayer graphene with Bernal stacking and a low concentration of adatoms. Assuming that the host bilayer lies on top of a substrate, we consider the case where impurities are adsorbed only on the upper layer. We describe non-magnetic impurities as a single orbital hybridized with carbon's pz states. The effect of impurity doping on the local density of states with and without a gated electric field perpendicular to the layers is analyzed. We look for Anderson localization in the different regimes and estimate the localization length. In the biased system, the field induced gap is partially filled by strongly localized impurity states. Interestingly, the structure, distribution and localization length of these states depend on the field polarization.Comment: 7 pages, 6 figure

Dinámica de meandros y riesgos hidrogeomorfológicos en Alcalá de Ebro y Cabañas de Ebro (Zaragoza)

[Resumen] Alcalá de Ebro y Cabañas de Ebro constituyen los enclaves de máximo riesgo hidrogeomorfológico del curso medio del Ebro. Las dos localidades se ubican dentro de la llanura de inundación y en sendas orillas cóncavas de meandros pronunciados. Se analiza la dinámica reciente del cauce de meandros libres en este sector aguas arriba de Zaragoza, así como los riesgos derivados de dicha dinámica, que han requerido sucesivas actuaciones de defensa[Abstract] Alcalá de Ebro & Cabañas de Ebro are the most threatened places with hydrogeomorphological risk in the middle Ebro. Both towns are placed in the floodplain and on each concave bank of sharp meanders. The recent dynamics of the free meanders river bed upstream from Zaragoza is analysed, as well as the risks derived that dynamics, which have required several successive protection works

Bilayer graphene under pressure: Electron-hole Symmetry Breaking, Valley Hall Effect, and Landau Levels

The electronic structure of bilayer graphene under pressure develops very interesting features with an enhancement of the trigonal warping and a splitting of the parabolic touching bands at the K point of the reciprocal space into four Dirac cones, one at K and three along the T symmetry lines. As pressure is increased, these cones separate in reciprocal space and in energy, breaking the electron-hole symmetry. Due to their energy separation, their opposite Berry curvature can be observed in valley Hall effect experiments and in the structure of the Landau levels. Based on the electronic structure obtained by Density Functional Theory, we develop a low energy Hamiltonian that describes the effects of pressure on measurable quantities such as the Hall conductivity and the Landau levels of the system.Comment: 11 pages, 9 figure

Influence of water deficits on grape berry growth

The effects of early and late water deficits on pericarp cell division and enlargement of Syrah berries (Vitis vinifera L.) was determined by DNA extraction and quantification. Different periods and different levels of water deficit were applied between anthesis and maturity to grapevines growing under controlled water supply in two consecutive years. DNA extraction profiles showed that water deficit did not affect cell division. Reduction of berry size and berry weight was caused exclusively by a decrease of pericarp volume, independent of the intensity of the water deficit or the stage of berry development. Decreased cell volume as a result of an early water deficit from flowering to veraison was irreversible. These results support the hypothesis that early water deficits modify the structural properties of the cell components and consequently cell wall extensibility, thereby limiting the subsequent enlargement of pericarp cells.

Globalizíación, Class Actions y Derecho de Trabajo

[Excerpt] El objeto principal de este artículo consiste en analizar la larga experiencia acumulada al otro lado del Atlántico, en Estados Unidos, en material de demandas extraterritoriales contra empresas norteamericanas ya desde los años setenta. Realizaremos una síntesis de los rasgos característicos de las class actions en ese país, en primer lugar, seguida por una breve Mirada al context internacional del Derecho del trabajo y la jurisprudencia en EE.UU., de los efectos extraterritoriales del Derecho del trabajo estadounidense, en segundo término, y un análisis pormenorizado de tales litigious en Europa