Equilibrium currents in a Corbino graphene ring

We address the description of a graphene Corbino disk in the context of a tight binding approach that includes both kinetic and Rashba spin-orbit coupling due to an external out-of-plane electric field. Persistent equilibrium currents are induced by an external magnetic field breaking time reversal symmetry. By direct diagonalization, we compute the spectrum and focus on the dispersion near the $K$ points at the Fermi level. The dispersion keenly reproduces that of a continuum model in spite of the complexity of the boundary conditions. We validate the assumptions of the continuum model in terms of predominant zig-zag boundaries conditions and weak sub-band coupling. The wave functions displaying the lowest transverse modes are obtained, showing the predominance of edge states with charge density at the zig-zag edges. The persistent charge currents, nevertheless, do not follow the traditional argument of current cancellation from levels below the Fermi level, and thus they depart in the tight-binding from those found in the continuum model.Comment: 8 pages, 6 figure

La formación inicial del profesorado de secundaria y su identidad profesional

La identidad profesional se ha constituido en un nuevo prisma para analizar el modo como los profesores sienten y ejercen su oficio. En España, la falta continuada de una formación inicial pedagógica, integrada en la propia carrera, ha dado lugar a una identidad profesional disciplinar, inadecuada para la educación obligatoria (Educación Secundaria Obligatoria [ESO]). Se describe el proceso de construcción de la identidad profesional en la formación inicial y se argumenta a favor de un planteamiento integrado de la formación disciplinar y pedagógica y, en tercer lugar, se analiza la renuncia continuada a una formación profesionalizadora, capaz de posibilitar una identidad profesional acorde con la función educativa y docente demandada

Fidelity as a marker of topological phase transitions in 2D Dirac materials

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Adsorption of lanthanide double-decker phthalocyanines on single-walled carbon nanotubes:structural changes and electronic properties as studied by density functional theory

Context: Molecular modeling of carbon nanotubes and lanthanide double-decker phthalocyanines hybrids is challenging due to the presence of 4f-electrons. In this paper, we analyzed the trends in structural changes and electronic properties when a lanthanide (La, Gd, and Lu) bisphthalocyanine molecule is adsorbed on the surface of two single-walled carbon nanotubes (SWCNTs) models: armchair and zigzag. The density functional theory (DFT) computations showed that the height of bisphthalocyanines complexes (LnPc2) when adsorbed on a nanotube (LnPc2+SWCNT) is the structural feature which is most affected by the nanotube model. The formation energy of the LnPc2+SWCNT hybrid depends on the metal atom and the nanotube chirality. LaPc2 and LuPc2 bind stronger to the zigzag nanotube, while for GdPc2, bonding to the armchair nanotube is the stronger one. The HOMO-LUMO gap energy (Egap) shows a correlation between the nature of lanthanide and the nanotube chirality. In the case of adsorption on armchair nanotube, Egap tends to match the gap of isolated LnPc2, whereas for adsorption on the zigzag nanotube, it is closer to the value for the isolated nanotube model. The spin density is localized on the phthalocyanines ligands (plus on Gd in the case of GdPc2), when the bisphthalocyanine is adsorbed on the surface of the armchair nanotube. For bonding to zigzag nanotube (ZNT), it extends over both components, except for LaPc2+ZNT, where spin density is found on the nanotube only. Method: All DFT calculations were carried out using the DMol3 module of Material Studio 8.0 software package from Accelrys Inc. The computational technique chosen was the general gradient approximation functional PBE in combination with a long-range dispersion correction developed by Grimme (PBE-D2), the double numerical basis set DN, and the DFT semi-core pseudopotentials.</p

Estudio de la temperatura del suelo en Puerto Rico.

Soil temperature measurements from a climate monitoring network in Puerto Rico were evaluated and the difference between mean summer and mean winter soil temperature, known as isotivity value, was calculated. Air and soil temperature was collected from five weather stations of the USDA-Natural Resources Conservation Service from sea level to 1,019 m above sea level and from different soil moisture regimes. Isotivity values ranged from 1.2 to 3.9° C with an average of 2.6° C. The 750-m elevation was identified as the limit between the isohyperthermic and isothermic soil temperature regimes in the perudic soil moisture regime in Puerto Rico. The greatest differences between mean annual soil temperature and mean annual air temperature were observed at Guánica, Combate and Guilarte (2.1 ° C) stations. The smallest differences were observed at Maricao (0.8° C) and Isabela (1.8° C) stations. The study also indicated that the mean annual soil temperature in Puerto Rico can be estimated by adding 1.8° C to the mean annual air temperature or by the equation y = -0.007x + 28.0° C. The equation indicates that 97 percent of the time the behavior of the mean annual soil temperature is a function of elevation. According to the updated soil temperature regime boundaries, eight soil series were established in the Soil Survey of San Germán Area. In an area under the isothermic soil temperature regime, four soil series were classified as Oxisols (Haploperox), two soil series as Inceptisols (Eutrudepts) and two soil series as Mollisols (Argiudolls). This is the first field recognition of the Haploperox soil great group in the United States and its territories.Se evaluaron mediciones de temperatura del suelo de la red de monitoreo de clima en Puerto Rico y se calculó la diferencia entre la temperatura promedio del suelo de verano y de invierno, conocida como valor de isotividad. Se tomaron datos de temperatura del aire y del suelo de cinco estaciones climatológicas del Servicio de Conservación de Recursos Naturales del Departamento de Agricultura de los Estados Unidos desde el nivel del mar hasta 1,019 m de elevación sobre el nivel del mar y a diferentes regímenes de humedad del suelo. Los valores de isotividad oscilaron entre 1.2 y 3.9° C con una media de 2.6° C. El límite entre el régimen de temperatura de suelo isohipertérmico e isotérmico en el régimen de humedad perúdico en Puerto Rico fue identificado a una elevación de 750 m. En las estaciones de Guánica, Combate y Guilarte se observaron las mayores diferencias entre la media anual de la temperatura del suelo y la media anual de la temperatura del aire (2.1° C). En las estaciones de Maricao (0.8° C) e Isabela (1.8° C) se observaron las menores diferencias. El estudio también indica que la media anual de la temperatura del suelo en Puerto Rico puede ser estimada añadiéndole 1.8° C a la media anual de la temperatura del aire o por la ecuación y = -0.007x + 28.0° C. La ecuación indica que el 97 por ciento del tiempo el comportamiento de la media anual de la temperatura del suelo es una función de la elevación. De acuerdo con la actualización de los límites de los regímenes de temperatura de suelo, se establecieron ocho series de suelo en el Catastro de Suelos del Área de San Germán. Cuatro series de suelo clasificaron como Oxisoles (Haploperox), dos series de suelos como Inceptisoles (Eutrudepts) y dos series de suelos como Molisoles (Argiudolls) en el área bajo régimen de temperatura isotérmico. Este es el primer reconocimiento en el campo del gran grupo de suelos Haploperox en los Estados Unidos de América y sus territorios

Features of water chemical composition of oligotrophic and eutrophic bogs in the South of the Tomsk region

On the basis of the actual material the analysis of chemical composition of bog waters in the territory of the South of the Tomsk region is carried out. The data on average concentration of macro and trace components, organic matter, pH of bog waters are obtained. Significant distinctions in a chemical composition of surface water for different types of bogs are revealed. The composition and macrostructure of humic acids by the example of eutrophic bogs is studied

Sociedad y Estado: la configuración del monopolio de la violencia

Ingrid Bolívar, investigadora del CINEP, se pregunta sobre los referentes conceptuales e históricos desde donde se piensa esta relación entre el monopolio de la fuerza y la génesis del Estado moderno, para mostrar que responde a un proceso paulatino de concentración del poder y de creciente interdependencia de los grupos de la sociedad.Introducción I.Orden político: mediación y monopolización El monopolio como mecanismo social II.La violencia se apuntala en y se reconoce por el Estado III.La centralidad de la violencia IV. Monopolio de la violencia e interdependencias de sociedades V.De monopolio privado a monopolio público VI.Monopolio y dominación indirecta VII.Monopolio de la violencia y soberanía VIII.Colombia: monopolio y colonización Consideración fina

Amplified Nanoscale Detection of Labelled Molecules via Surface Electrons on Diamond

The detection of individual molecules and their dynamics has been a long-standing challenge in the field of nanotechnology. In this work, we present a method that utilizes a nitrogen vacancy (NV) center and a dangling-bond on the diamond surface to measure the coupling between two electronic targets tagged on a macromolecule. To achieve this, we design a multi-tone dynamical decoupling sequence that leverages the strong interaction between the nitrogen vacancy center and the dangling bond. In addition, this sequence minimizes the impact of decoherence finally resulting in an increased signal-to-noise ratio. This proposal has the potential to open up new avenues for fundamental research and technological innovation in distinct areas such as biophysics and biochemistry.Comment: 9 pages, 6 figure

Effects of a strategy for the promotion of physical activity in students from Bogotá

OBJECTIVE: To examine the effect of the promotion of physical activity during recess on the levels of physical activity, sedentary behaviors, and adiposity of Colombian students. METHODS: Three schools were randomly selected by an intervention group in Bogotá, Colombia, in 2013: Intervention (Active Module of Active Recess – MARA) + Text Messages (SMS) (MARA+SMS group), intervention (MARA group), control (control group). Intervention was implemented for ten weeks. The duration and intensity of physical activity and sedentary behaviors were measured objectively using accelerometers Actigraph-GT3X+. Adiposity was measured by body mass index and fat percentage. We measured at baseline (T0) and during the tenth week of intervention (T1). We evaluated the effect of the intervention using a difference-in-difference analysis (DID). RESULTS: We included 120 students (57.5% girls; mean age = 10.5 years; standard deviation [SD] = 0.64). There was a significant increase in the mean daily minutes of moderate to vigorous physical activity in the MARA group (Difference T1-T0 = 6.1 minutes, standard error [SE] = 3.49, p = 0.005) in relation to the control group. There were no significant changes in the minutes of moderate to vigorous physical activity in the MARA+SMS group (Difference T1-T0 = -1.0 minute; SE = 3.06; p = 0.363). The minutes decreased in the control group (Difference T1-T0 = -7.7 minutes; SE = 3.15; p = 0.011). The minutes of sedentary behaviors decreased in the MARA and MARA+SMS groups and increased in the control group (MARA Difference T1-T0 = -15.8 minutes; SE = 10.05; p= 0.279; MARA+SMS Difference T1-T0 = -11.5 minutes; SE = 8.80; p= 0.869; Control Difference T1-T0 = 10.9 minutes; SE = 9.07; p = 0.407). There was a higher participation in the MARA group in relation to the MARA+SMS group (MARA group = 34.4%; MARA+SMS group = 12.1%). There were no significant changes in adiposity at 10 weeks according to difference-in-differences analysis (body mass index p: ΔMARA+SMS group versus Δcontrol group = 0.945, ΔMARA group versus Δcontrol group = 0.847, ΔMARA+SMS group versus ΔMARA group = 0.990; FP p ΔMARA+SMS group versus Δcontrol group = 0.788, ΔMARA group versus Δcontrol group = 0.915, ΔMARA+SMS group versus ΔMARA group = 0.975). CONCLUSIONS: The Active Module of Active Recess is a promising strategy to increase physical activity levels and decrease sedentary behavior in students. The addition of Text Messages was not associated with increased moderate to vigorous physical activity or changes in adiposit