In-gap impurity states as the hallmark of the Quantum Spin Hall phase

We study the different response to an impurity of the two topologically different phases shown by a two dimensional insulator with time reversal symmetry, namely, the Quantum Spin Hall and the normal phase. We consider the case of graphene as a toy model that features the two phases driven, respectively, by intrinsic spin-orbit coupling and inversion symmetry breaking. We find that strictly normalizable in-gap impurity states only occur in the Quantum Spin Hall phase and carry dissipationless current whose quirality is determined by the spin and pseudospin of the residing electron. Our results imply that topological order can be unveiled by local probes of defect states.Comment: 5 pages, 3 figure

On the void explanation of the Cold Spot

The integrated Sachs-Wolfe (ISW) contribution induced on the cosmic microwave background by the presence of a supervoid as the one detected by Szapudi et al. (2015) is reviewed in this letter in order to check whether it could explain the Cold Spot (CS) anomaly. Two different models, previously used for the same purpose, are considered to describe the matter density profile of the void: a top hat function and a compensated profile produced by a Gaussian potential. The analysis shows that, even enabling ellipticity changes or different values for the dark-energy equation of state parameter $\omega$, the ISW contribution due to the presence of the void does not reproduce the properties of the CS. Finally, the probability of alignment between the void and the CS is also questioned as an argument in favor of a physical connection between these two phenomena

A wide family of singularity-free cosmological models

In this paper a family of non-singular cylindrical perfect fluid cosmologies is derived. The equation of state corresponds to a stiff fluid. The family depends on two independent functions under very simple conditions. A sufficient condition for geodesic completeness is provided.Comment: 7 pages, RevTeX

Exploring two-spin internal linear combinations for the recovery of the CMB polarization

We present a methodology to recover cosmic microwave background (CMB) polarization in which the quantity $P = Q+ iU$ is linearly combined at different frequencies using complex coefficients. This is the most general linear combination of the $Q$ and $U$ Stokes parameters which preserves the physical coherence of the residual contribution on the CMB estimation. The approach is applied to the internal linear combination (ILC) and the internal template fitting (ITF) methodologies. The variance of $P$ of the resulting map is minimized to compute the coefficients of the linear combination. One of the key aspects of this procedure is that it serves to account for a global frequency-dependent shift of the polarization phase. Although in the standard case, in which no global E-B transference depending on frequency is expected in the foreground components, minimizing $\left\langle |P|^2\right\rangle$ is similar to minimizing $\left\langle Q^2\right\rangle$ and $\left\langle U^2\right\rangle$ separately (as previous methodologies proceed), multiplying $Q$ and $U$ by different coefficients induces arbitrary changes in the polarization angle and it does not preserve the coherence between the spinorial components. The approach is tested on simulations, obtaining a similar residual level with respect to the one obtained with other implementations of the ILC, and perceiving the polarization rotation of a toy model with the frequency dependence of the Faraday rotation.Comment: 14 pages, 8 figures, 2 tables. Accepted for publication in MNRA

Searching for a dipole modulation in the large-scale structure of the Universe

Several statistical anomalies in the CMB temperature anisotropies seem to defy the assumption of a homogeneous and isotropic universe. In particular, a dipole modulation has been detected both in WMAP and Planck data. We adapt the methodology proposed by Eriksen et al. (2007) on CMB data to galaxy surveys, tracing the large-scale structure. We analyse the NRAO VLA Sky Survey (NVSS) data at a resolution of ~2 degrees for three different flux thresholds: 2.5, 5.0 and 10.0 mJy respectively. No evidence of a dipole modulation is found. This result suggests that the origin of the dipole asymmetry found in the CMB cannot be assigned to secondary anisotropies produced at redshifts around z = 1. However, it could still have been generated at redshifts higher or lower, such as the integrated Sachs-Wolfe effect produced by the local structures. Other all-sky surveys, like the infrared WISE catalogue, could help to explore with a high sensitivity a redshift interval closer than the one probed with NVSS.Comment: 6 pages, 2 figures. Some minor changes have been done from the original manuscript. This paper is accepted by MNRA

Analysis of the start to the first hurdle in 110m hurdles at the IAAF World Athletics Championships Beijing 2015

The purpose of this study was to use observational analysis to evaluate the relationships between variables measured at the start of the men’s 110 hurdles event and race performance itself. Data were obtained for competitors in 2015 IAAF World Athletics Ch ampionships, in Beijing, China. The athletes’ start was quantified by reaction time and time to the first hurdle; their action over the first hurdle was quantified by the take - off distance (i.e., the distance from the last step to the first hurdle), the la nding distance, and the total distance in the air over the first hurdle. Regression analyses revealed that the combination of one measure of the start (either reaction time or time to the first hurdle) and the measure of propulsion over the first hurdle (d istance in air over the first hurdle) predicted performance (SEE = 0.23 s in the heats, SEE = 0.16 s in the semi - finals, SEE = 0.09 s in the finals). In addition, looking at performances in the finals, where all athletes with available data used a seven - st ep approach to the first hurdle, inclusion of stride length data improved the prediction somewhat (SEE = 0.07 s). The results demonstrate that a combination of a fast start, rapid acceleration, and strong drive over the first hurdle quantifiably explains a nd contributes to performance in the men’s 110 m hurdles at the highest level

The collection of amphibians from Madrid at the Museo Nacional de Ciencias Naturales and its utility in conservation

[EN] We present the revised catalogue of the amphibians deposited in the “Colección de Anfibios y Reptiles” of the Museo Nacional de Ciencias Naturales that have been collected in the Comunidad Autónoma of Madrid. It consists of 2272 records of 18 species, including all species present in Madrid except Hyla meridionalis. We evaluate the collection on the basis of the representation of the specimens collected in relation with: 1) the present distribution of each amphibian species in Madrid, considering the number of UTM 10x10 km grid cells represented in the collection in relation with the total number of grids occupied by each species in Madrid; 2) the number of intraspecific subunits that are relevant from a conservation perspective (subspecies or groups of populations that are differentiated on ecological or genetic grounds) that are represented in the collection. Representation values range from 0% (Hyla meridionalis) to 50% (Triturus alpestris). We also include information on the conservation status of some populations from historical collection sites and conclude that at least 10 breeding sites have disappeared as a consequence of human activities, with the subsequent local extinction of their associated amphibian populations. We have also documented the disappearance of some species from unaltered areas. Finally, we discuss the utility of scientific collections in facing practical aspects of the management and conservation of endangered groups like amphibians.[ES] Se presenta el catálogo revisado de los anfibios de la Colección de Anfibios y Reptiles del Museo Nacional de Ciencias Naturales colectados en la Comunidad de Madrid. En total, consta de 2272 entradas correspondientes a 18 especies, que incluyen todas las presentes en la Comunidad excepto Hyla meridionalis. Se valora la colección en función del grado de representatividad de los ejemplares de la colección en relación con: 1) la distribución actual de las especies de anfibios en Madrid, considerando el % de cuadrículas UTM de 10x10 km del total del área de distribución de cada especie que se encuentran representadas en la colección; 2) el número de unidades infraespecíficas relevantes desde el punto de vista de la conservación (subespecies o grupos de poblaciones diferenciados ecológica o genéticamente) representados en la colección para cada especie. Los valores de representatividad obtenidos oscilan entre el 0% (Hyla meridionalis) y el 50% (Triturus alpestris). Además, se aporta información acerca de algunas de las poblaciones asentadas en los lugares de colecta históricos, lo que permite concluir que al menos 10 puntos de reproducción han desaparecido durante los últimos años como resultado de la actividad humana, con la consiguiente extinción local de esas poblaciones de anfibios. Por otro lado, en ciertos casos también se ha documentado la desaparición de especies en áreas aparentemente inalteradas. Finalmente, se discute la utilidad de las colecciones museológicas para afrontar aspectos prácticos relacionados con la gestión y conservación de grupos amenazados como los anfibios.El trabajo de IMS estáfinanciado por una beca predoctoral MNCN-CSIC-CAM.Peer reviewe

Reporte de caso: quemadura de la vía aérea

ResumenLa quemadura de la vía aérea, consecuencia de encender un tubo endotraqueal con electrocauterio, presenta escasa incidencia, pero puede provocar lesiones graves o incluso la muerte. Se presenta un caso de un incendio causado por rotura del tubo endotraqueal secundario a contacto con electrocauterio durante una resección de tumor facial. En este caso las causas primarias de fuego fueron el oxígeno a FiO2 no mínima empleado para la ventilación, y la electrocauterización de alta potencia utilizada para la resección y el control de la hemorragia. En este reporte se nombran los métodos de prevención de un incendio de las vías respiratorias y el tratamiento de urgencia cuando se produce. A pesar de su baja incidencia, anestesiólogos y cirujanos deben tener un tratamiento de urgencia de incendios de vía aérea en mente y estar al tanto de los métodos de prevención.AbstractAlthough the incidence of airway burns that occur when the endotracheal tube is ignited by the electrocautery is low, it is right to assume that the resulting injuries may be severe and even fatal. A case is presented of fire caused by the rupture of an endotracheal tube secondary to contact with the electrocautery during the resection of a facial tumor. In this case, the primary sources of fire were oxygen at a non-minimal FiO2 used for ventilation, and the high-powered electrocautery used for resection and bleeding control. This report will cover the methods for preventing airway fires and the emergency treatment should they happen. Despite the low incidence, both anesthesiologists as well as surgeons must have in mind an emergency treatment of airway fires and must have knowledge of preventive methods