Effects of constraints in general branched molecules: A quantitative ab initio study in HCO-L-Ala-NH2

A general approach to the design of accurate classical potentials for protein folding is described. It includes the introduction of a meaningful statistical measure of the differences between approximations of the same potential energy, the definition of a set of Systematic and Approximately Separable and Modular Internal Coordinates (SASMIC), much convenient for the simulation of general branched molecules, and the imposition of constraints on the most rapidly oscillating degrees of freedom. All these tools are used to study the effects of constraints in the Conformational Equilibrium Distribution (CED) of the model dipeptide HCO-L-Ala-NH2. We use ab initio Quantum Mechanics calculations including electron correlation at the MP2 level to describe the system, and we measure the conformational dependence of the correcting terms to the naive CED based in the Potential Energy Surface (PES) without any simplifying assumption. These terms are related to mass-metric tensors determinants and also occur in the Fixman's compensating potential. We show that some of the corrections are non-negligible if one is interested in the whole Ramachandran space. On the other hand, if only the energetically lower region, containing the principal secondary structure elements, is assumed to be relevant, then, all correcting terms may be neglected up to peptides of considerable length. This is the first time, as far as we know, that the analysis of the conformational dependence of these correcting terms is performed in a relevant biomolecule with a realistic potential energy function.Comment: 8 pages, 1 figure, LaTeX, aipproc style (included

An intercomparison of subtropical cut-off lows in the Southern Hemisphere using recent reanalyses: ERA-Interim, NCEP-CFRS, MERRA-2, JRA-55, and JRA-25

Four recent reanalysis products ERA-Interim, NCEP-CFSR, MERRA-2 and JRA-55 are evaluated and compared to an older reanalysis JRA-25, to quantify their confidence in representing Cut-off lows (COLs) in the Southern Hemisphere. The climatology of COLs based on the minima of 300-hPa vorticity (ξ300) and 300-hPa geopotential (Z300) provides different perspectives of COLs and contributes to the understanding of the discrepancies observed in the literature regarding their numbers and seasonality. The COLs compare better among the newest reanalyses than compared to the older reanalysis JRA-25. The difference in number between the latest reanalyses are generally small for both ξ300 and, with more COLs identified in ξ300 than in Z300 for all reanalyses. The spatial differences observed between the newest reanalyses are mainly due to differences in the track lengths, which is larger in ERA-Interim and JRA-55 than in NCEP-CFSR and MERRA-2, resulting in disparities in the track density. This is likely due to the difference in the assimilation data system used in each reanalysis product. The largest differences in intensities occur in the ξ300, because this field is very sensitive to the reanalysis resolution. The mean separation distance of the COLs that match between the latest reanalyses are generally small, while the older JRA-25 has a broader distribution and larger number of matches with relatively large distances, indicating larger uncertainties in location of COLs. The results show significant improvements for the most recent reanalyses compared to the older JRA-25 reanalysis, indicating a progress in representing the COL properties

Cooler and bigger than thought? Planetary host stellar parameters from the InfraRed Flux Method

Effective temperatures and radii for 92 planet-hosting stars as determined from the InfraRed Flux Method (IRFM) are presented and compared with those given by other authors using different approaches. The IRFM temperatures we have derived are systematically lower than those determined from the spectroscopic condition of excitation equilibrium, the mean difference being as large as 110 K. They are, however, consistent with previous IRFM studies and with the colors derived from Kurucz and MARCS model atmospheres. Comparison with direct measurements of stellar diameters for 7 dwarf stars, which approximately cover the range of temperatures of the planet-hosting stars, suggest that the IRFM radii and temperatures are reliable in an absolute scale. A better understanding of the fundamental properties of the stars with planets will be achieved once this discrepancy between the IRFM and the spectroscopic temperature scales is resolved.Comment: 15 pages, 4 figures. Accepted for publication in Ap

Cuando de salud se trata, ¿a dónde acuden las personas?

Cartel presentado en la Segunda Conferencia Internacional de Comunicación en Salud, celebrada el 23 de octubre de 2015 en la Universidad Carlos III de MadridEsta investigación pretendió conocer las relaciones vecinales y sociales de los/as habitantes de dos de los barrios de la localidad de Bosa y de la localidad de Engativá (Bogotá) con las droguerías como instituciones de respuesta a las situaciones de salud, y si éstas pueden ser consideradas consideradas como lugares en donde se suple la falencia del servicio de salud y asimismo, se instauran relaciones sociales que van más allá de la venta de un producto. Asimismo, conocer las razones por las que los/las habitantes de las localidades de Bosa y Engativá, en dos de sus barrios acuden a las droguerías antes que a las entidades de salud; y qué tipo de población acude con más frecuencia. De acuerdo con lo anterior, se consideró como objetivo general analizar las relaciones sociales y vecinales generadas por los servicios de salud que prestan las droguerías de las dos localidades en su zona central respectivamente como instituciones de respuesta a las situaciones o crisis de salud en estas zonas específicas. Esta investigación tuvo un enfoque hermenéutico interpretativo y tuvo tres etapas: Diagnóstico: A través de observación participante en las droguerías seleccionadas; Trabajo de campo: aplicando las técnicas de entrevista a farmaceutas de las droguerías seleccionadas y encuestas escritas a los clientes consumidores de la farmacia y a habitantes de sus alrededores; Sistematización mediante la recopilación de datos e información y análisis de los mismos, obteniendo como principal respuesta a las preguntas de investigación que las personas prefieren las droguerías antes que los establecimiento de salud como EPS y hospitales por la cercanía, confianza, mejor atención, efectividad en diagnóstico y formulación ya que estando las droguerías dentro de los barrios, y su cercanía con la comunidad, se convierten en un espacio de interrelaciones vecinales

Sensitivity of identifying cut‑off lows in the Southern Hemisphere using multiple criteria: Implications for numbers, seasonality and intensity

Cut-off Low (COLs) are often associated with heavy precipitation and strong wind events, but there are still uncertainties on how their identification affect the numbers and seasonality. This paper aims to determine the sensitivity of identifying Southern Hemisphere COLs in the ERA-Interim reanalysis to different types of identification criteria. Upper-level cyclones are initially tracked on the 300 hPa level using relative vorticity and geopotential in order to present different perspectives. This reveals significant differences between the numbers and length of the identified tracks for the two fields. To identify the COLs different post-tracking filters are applied which are divided into two steps. Firstly, three filters are considered to separate cut-off lows from open troughs by sampling winds at different offset radial distances from the upper-level cyclonic centres. Secondly, potential vorticity and temperature criteria are imposed to determine how these conditions affect the identified COLs in terms of numbers, seasonality and intensity. It was found that methods based on multiple criteria restrict the COL identification by imposing specific characteristics, while methods based on simpler schemes (e.g. using only winds) can detect larger samples of COLs observed visually in the geopotential maps. Although it is difficult to say which method is more accurate in identifying COLs, because of the subjective aspect of observer’s assessment, a scheme using only winds should be more representative of reality as this simply imposes on the detection system a cyclonic circulation appearance regardless of the physical and dynamical characteristics. Therefore, this type of method could be considered as a standard method for identifying COLs that can be used for either operational or research purposes

Twisted Nano-optics: Manipulating Light at the Nanoscale with Twisted Phonon Polaritonic Slabs

Recent discoveries have shown that when two layers of van der Waals (vdW) materials are superimposed with a relative twist angle between their respective in-plane principal axes, the electronic properties of the coupled system can be dramatically altered. Here, we demonstrate that a similar concept can be extended to the optics realm, particularly to propagating polaritons, hybrid light-matter interactions. To do this, we fabricate stacks composed of two twisted slabs of a polar vdW crystal (MoO3) supporting low-loss anisotropic phonon polaritons (PhPs), and image the propagation of the latter when launched by localized sources (metal antennas). Our images reveal that under a critical angle the PhPs isofrequency curve (determining the PhPs momentum at a fixed frequency) undergoes a topological transition. Remarkably, at this angle, the propagation of PhPs is strongly guided along predetermined directions (canalization regime) with no geometrical spreading (diffraction-less). These results demonstrate a new degree of freedom (twist angle) for controlling the propagation of polaritons at the nanoscale with potential for nano-imaging, (bio)-sensing, quantum applications and heat management

Integración de Cartotecas Virtuales como herramienta de apoyo en la investigación histórica y social

En la actualidad, la casi totalidad de las cartotecas que se encuentran en la Web son colecciones de imágenes provenientes de la digitalización de mapas originalmente en soporte papel. Ese tipo de archivos gráficos proporcionan al investigador la posibilidad de acceder a la información cartográfica histórica y visualizarla, con un grado de calidad que depende de la calidad del proceso de digitalización y de las limitaciones impuestas por el propietario de los mismos. En la mayoría de los casos, el acceso a estas cartotecas sólo sirve para una primera aproximación y no es posible utilizar esos mapas para un trabajo científico debido a las escasas herramientas disponibles para medir, comparar, analizar y/o combinar estos recursos con otro tipo de cartografía. Por ello, el establecimiento de las Cartotecas Virtuales como herramienta de apoyo a los proyectos históricos en los que se involucra a un gran número de investigadores nacionales e internacionales, supone un avance hacia la patente necesidad de los historiadores y documentalistas de poder acceder de manera remota a toda la información existente y que pueda ser ubicable a través de un único sitio que facilite su consulta

High tuberculosis burden among people living with HIV in southern Mozambique

Tuberculosis (TB) remains an important public health concern, and a leading cause of disease and death worldwide. Mozambique is one of the few high TB burden countries where TB figures have not improved in recent years, with an estimated TB incidence in 2013 of 552 cases per 100 000 population [1]. With 58% of all notified TB cases being HIV-positive, Mozambique also has one of the highest TB/HIV co-infection rates. Published data on the burden of TB or HIV disease in the country are scarce, and improving epidemiological surveillance has been identified as an urgent step to improve TB control [2]

Homeopathic Perovskite Solar Cells: Effect of Humidity during Fabrication on the Performance and Stability of the Device

Rapid degradation in humid environments is a major drawback of methylammonium lead iodide (CH3NH3PbI3), which is the archetypical component of perovskite solar cells. In this work, we have investigated the aging and degradation kinetics of CH3NH3PbI3 films and devices fabricated under controlled conditions as a function of relative humidity (RH) and compared their performance with those that were prepared under dry conditions. The aging and degradation kinetics is monitored by optical absorption and impedance spectroscopy measurements under monochromatic illumination at two different wavelengths. Aged devices show a substantial difference between the recombination rate under red and blue light illumination, which is attributed to the enhancement of local recombination routes upon aging. Interestingly, we observe that this feature is less pronounced in devices prepared under conditions of the highest RH of 50%. In general, we found that these devices keep their original electric properties and withstand a humid environment better. Chemical analysis by X-ray photoelectron spectroscopy reveals the presence of coordinating water in the CH3NH3PbI3 crystalline structure. This indicates that the presence of a small amount of water has a beneficial effect against degradation in a humid environment