1,681 research outputs found

    Cosmological simulations using a static scalar-tensor theory

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    We present Λ\LambdaCDM NN-body cosmological simulations in the framework of a static general scalar-tensor theory of gravity. Due to the influence of the non-minimally coupled scalar field, the gravitational potential is modified by a Yukawa type term, yielding a new structure formation dynamics. We present some preliminary results and, in particular, we compute the density and velocity profiles of the most massive group.Comment: 4 pages, 6 figures, to appear in Journal of Physics: Conference Series: VII Mexican School on Gravitation and Mathematical Physics. 26 November to 1 December 2006, Playa del Carmen, Quintana Roo, Mexic

    Quantum gravity corrections to neutrino propagation

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    Massive spin-1/2 fields are studied in the framework of loop quantum gravity by considering a state approximating, at a length scale L\cal L much greater than Planck length P=1.2×1033\ell_P=1.2\times 10^{-33}cm, a spin-1/2 field in flat spacetime. The discrete structure of spacetime at P\ell_P yields corrections to the field propagation at scale L\cal L. Next, Neutrino Bursts (pˉ105{\bar p}\approx 10^5GeV) accompaning Gamma Ray Bursts that have travelled cosmological distances, L1010L\approx 10^{10}l.y., are considered. The dominant correction is helicity independent and leads to a time delay w.r.t. the speed of light, cc, of order (pˉP)L/c104({\bar p} \ell_P) L/c\approx 10^4s. To next order in pˉP{\bar p} \ell_P the correction has the form of the Gambini and Pullin effect for photons. Its contribution to time delay is comparable to that caused by the mass term. Finally, a dependence Los1pˉ2PL_{\rm os}^{-1} \propto {\bar p}^2 \ell_P is found for a two-flavour neutrino oscillation length.Comment: RevTeX, 5pp, no figures. Notation of a sum in Eq.(2) improved. Slight modifications in redaction. Final version to appear in Phys. Rev. Let

    Sistema de Automatización de Acondicionadores de Aire y Luminarias para Edificios utilizando sensores de Bajo Costo

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    El término Domótica procede de la palabra francesa domotique que podría definirse como el conjunto de servicios proporcionados por sistemas tecnológicos integrados para satisfacer las necesidades básicas de seguridad, comunicación, gestión energética y confort del hombre y de su entorno más cercano. Este proyecto consiste en un sistema inteligente basado en open software/open hardware, utilizando como base un Arduino. El sistema desarrollado mejora las condiciones del entorno donde se encuentra instalado, por medio de la automatización lograda para las luminarias y los aires acondicionados. Permitiendo un entorno con más flexibilidad, escalabilidad, robustez, amigabilidad, tiempos de respuesta adecuada, configurable, alertas para seguridad, control de acceso de usuarios, y finalmente ahorro de energía.Este sistema es desarrollado con el objetivo que pueda ser implementado en edificios tanto en el servicio público como privado

    TRASPLANTE SIMULTÿNEO DE PANCREAS-RIÿÿN. CONCEPTOS ACTUALES Y EXPERIENCIA EN CLÿNICA LAS CONDES

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    RESUMENEl trasplante de páncreas-riñón (TPR) para pacientes portadores de diabetes mellitus tipo 1 (DM1) con insuficiencia renal crónica terminal, ha demostrado ser una terapia eficaz para alcanzar el estado de normoglicemia de manera estable, con la consecuente disminución de las complicaciones crónicas de la DM y mejoría de la expectativa y calidad de vida. Actualmente, en casos seleccionados, se ha planteado el trasplante de páncreas (TP) como una alternativa para los pacientes con diabetes mellitus tipo 2 (DM2) considerando la diferencia entre los pacientes del tipo 1 y 2. Si bien es menos frecuente en la experiencia mundial, trasplantar pacientes con DM2 demuestra cifras alentadoras y comparables con el TP en enfermos portadores de DM1. En general, pacientes que desarrollan enfermedad renal terminal secundaria a diabetes 1 o 2 que requieren insulina, no obesos, deben ser considerados para el trasplante de páncreas con riñón simultáneo o secuencial. Clínica Las Condes es la de mayor experiencia en Chile, con resultados muy comparables a centros de gran importancia a nivel internacional.ObjetivoDar a conocer la situación actual del trasplante de páncreas y sus modalidades en el mundo y mostrar la experiencia en TPR en Clínica Las Condes en la sobrevida de los pacientes, de injerto de páncreas e injerto de riñón en 10 años y sus complicaciones, además de las técnicas quirúrgicas realizadas.MétodoSe recolectó la información de 16 pacientes sometidos a trasplante páncreas-riñón en Clínica Las Condes entre 1994-2014, analizando las variables con estadística descriptiva.ResultadosDe los 16 enfermos, 9 de ellos fueron hombres, la edad promedio fue 38,7 años al momento del trasplante, el tiempo promedio de diabetes fue 23,5+/-7.3 años. Todos los injertos pancreáticos fueron anastomosados a los vasos ilíacos comunes derechos en forma término-terminal y el duodeno fue anastomosado en 8 casos a la vejiga y en los últimos 8 al íleon. La sobrevida de los pacientes a 10 años fue del 81%, del injerto de páncreas el 82% y del injerto renal el 65%. La complicación post operatoria más importante fue sepsis, causando la muerte en 2 pacientes. Y entre las complicaciones de tipo inmunológico, 8 pacientes presentaron rechazo agudo, siendo manejados con terapia esteroidal de rescate o timo globulina.SUMMARYCombined kidney pancreas trasplant (PKT) in diabetes mellitus type 1 (DM1) patients with end stage renal disease, has proven to be an effective therapy to reach normoglicemia stability, with the consequent reduction of diabetes chronic complications an improvement in life expectancy and Quality of Life. Currently in selected cases of type 2 diabetes mellitus (DM2) patients with terminal nephropathy it has been proposed pancreas transplantation (PT) as an effective alternative. The results have been comparable between DM1 and DM2 patients. Patients who develop end stage renal disease secondary to type 1 or 2 DM, insulin dependent, non obese, should be considered for PKT. Clínica Las Condes has one of the mayor experience in Chile, in PKT, with comparable results to centers of great importance of International Level.ObjectiveTo show the situation of Pancreas Transplantation and its different modalities in the world. Also to show the experience in PKT at Clinica Las Condes, in 10 years patient's survival, in pancreas and kidney graft survival and complications and the surgical techniques.MethodInformation collected from 16 patients undergoing PKT at Clinica Las Condes between 1994-2014, analyzing the variables with descriptive statistics.ResultsOf the 16 patients, 9 were men, average age 38.7 years at transplant time; the average time of diabetes was 23.5+/-7.3 years. All pancreatic grafts were term-terminal to anastomosed the right iliac common vessels and duodenum was anastomosed is 8 cases to the bladder and in the last 8 to the ileum. Patient survival at 10 years was 81%, pancreatic graft 82% and 65% renal graft. The most relevant postoperative complication was sepsis, killing two patients. The immune complications were presented in eight patients. It was acute rejection, being managed with steroid therapy or thymoglobuline

    A comparative study on the passivation and localized corrosion of α- and β-brass in borate buffer solutions containing sodium chloride—II. X-ray photoelectron and Auger electron spectroscopy data

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    The composition of corrosion layers formed on α-, β- and (α + β)-brass anodized in the passive region in borate-boric acid buffer and 0.5 M NaCl + borate-boric acid buffer (pH 9) was studied comparatively by X-ray photo-electron and Auger electron spectroscopy. Passivation of brass in both solutions involves the formation of a complex passive layer consisting of ZnO and Cu2O. In both solutions, the ZnO electroformation results in a dezincification so that a thin Cu rich layer is formed at the alloy/metal oxide interface. Passive layer composition and dezincification of the alloy surface explain the localized corrosion resistance of brass as compared to polycrystalline Cu and Zn.Instituto de Investigaciones Fisicoquímicas Teóricas y AplicadasFacultad de Ciencias Exacta

    A comparative study on the passivation and localized corrosion of α- and β-brass in borate buffer solutions containing sodium chloride : II. X-ray photoelectron and Auger electron spectroscopy data

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    The composition of corrosion layers formed on α-, β- and (α + β)-brass anodized in the passive region in borate-boric acid buffer and 0.5 M NaCl + borate-boric acid buffer (pH 9) was studied comparatively by X-ray photo-electron and Auger electron spectroscopy. Passivation of brass in both solutions involves the formation of a complex passive layer consisting of ZnO and Cu2O. In both solutions, the ZnO electroformation results in a dezincification so that a thin Cu rich layer is formed at the alloy/metal oxide interface. Passive layer composition and dezincification of the alloy surface explain the localized corrosion resistance of brass as compared to polycrystalline Cu and Zn.Instituto de Investigaciones Fisicoquímicas Teóricas y AplicadasFacultad de Ciencias Exacta

    Diagnosis of cardiac surgery-associated acute kidney injury: State of the art and perspectives

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    Producción CientíficaDiagnosis of cardiac surgery-associated acute kidney injury (CSA-AKI), a syndrome of sudden renal dysfunction occurring in the immediate post-operative period, is still sub-optimal. Standard CSA-AKI diagnosis is performed according to the international criteria for AKI diagnosis, afflicted with insufficient sensitivity, specificity, and prognostic capacity. In this article, we describe the limitations of current diagnostic procedures and of the so-called injury biomarkers and analyze new strategies under development for a conceptually enhanced diagnosis of CSA-AKI. Specifically, early pathophysiological diagnosis and patient stratification based on the underlying mechanisms of disease are presented as ongoing developments. This new approach should be underpinned by process-specific biomarkers including, but not limited to, glomerular filtration rate (GFR) to other functions of renal excretion causing GFR-independent hydro-electrolytic and acid-based disorders. In addition, biomarker-based strategies for the assessment of AKI evolution and prognosis are also discussed. Finally, special focus is devoted to the novel concept of pre-emptive diagnosis of acquired risk of AKI, a premorbid condition of renal frailty providing interesting prophylactic opportunities to prevent disease through diagnosis-guided personalized patient handling. Indeed, a new strategy of risk assessment complementing the traditional scores based on the computing of risk factors is advanced. The new strategy pinpoints the assessment of the status of the primary mechanisms of renal function regulation on which the impact of risk factors converges, namely renal hemodynamics and tubular competence, to generate a composite and personalized estimation of individual risk.Instituto de Salud Carlos III y Fondo Europeo de Desarrollo Regional (FEDER) - (grant PI18/00996, PI21/01226), Unión Europea, Red de Investigación Renal (Enfermedad Renal) - (grant RICORS2040)Unión Europea–NextGenerationEU, Mecanismo para la Recuperación y la Resiliencia (MRR) - (grant RD21/0005/0004)Junta de Castilla y León (Consejería de Educación) y Fondo Europeo de Desarrollo Regional (FEDER) - (grant IES160P20

    The CARMENES search for exoplanets around M dwarfs: Two planets on opposite sides of the radius gap transiting the nearby M dwarf LTT 3780

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    Full list of authors: Nowak, G.; Luque, R.; Parviainen, H.; Pallé, E.; Molaverdikhani, K.; Béjar, V. J. S.; Lillo-Box, J.; Rodríguez-López, C.; Caballero, J. A.; Zechmeister, M.; Passegger, V. M.; Cifuentes, C.; Schweitzer, A.; Narita, N.; Cale, B.; Espinoza, N.; Murgas, F.; Hidalgo, D.; Zapatero Osorio, M. R.; Pozuelos, F. J.; Aceituno, F. J.; Amado, P. J.; Barkaoui, K.; Barrado, D.; Bauer, F. F.; Benkhaldoun, Z.; Caldwell, D. A.; Casasayas Barris, N.; Chaturvedi, P.; Chen, G.; Collins, K. A.; Collins, K. I.; Cortés-Contreras, M.; Crossfield, I. J. M.; de León, J. P.; Díez Alonso, E.; Dreizler, S.; El Mufti, M.; Esparza-Borges, E.; Essack, Z.; Fukui, A.; Gaidos, E.; Gillon, M.; Gonzales, E. J.; Guerra, P.; Hatzes, A.; Henning, Th.; Herrero, E.; Hesse, K.; Hirano, T.; Howell, S. B.; Jeffers, S. V.; Jehin, E.; Jenkins, J. M.; Kaminski, A.; Kemmer, J.; Kielkopf, J. F.; Kossakowski, D.; Kotani, T.; Kürster, M.; Lafarga, M.; Latham, D. W.; Law, N.; Lissauer, J. J.; Lodieu, N.; Madrigal-Aguado, A.; Mann, A. W.; Massey, B.; Matson, R. A.; Matthews, E.; Montañés-Rodríguez, P.; Montes, D.; Morales, J. C.; Mori, M.; Nagel, E.; Oshagh, M.; Pedraz, S.; Plavchan, P.; Pollacco, D.; Quirrenbach, A.; Reffert, S.; Reiners, A.; Ribas, I.; Ricker, G. R.; Rose, M. E.; Schlecker, M.; Schlieder, J. E.; Seager, S.; Stangret, M.; Stock, S.; Tamura, M.; Tanner, A.; Teske, J.; Trifonov, T.; Twicken, J. D.; Vanderspek, R.; Watanabe, D.; Wittrock, J.; Ziegler, C.; Zohrabi, F.We present the discovery and characterisation of two transiting planets observed by the Transiting Exoplanet Survey Satellite (TESS) orbiting the nearby (d∗ ≈ 22 pc), bright (J ≈ 9 mag) M3.5 dwarf LTT 3780 (TOI-732). We confirm both planets and their association with LTT 3780 via ground-based photometry and determine their masses using precise radial velocities measured with the CARMENES spectrograph. Precise stellar parameters determined from CARMENES high-resolution spectra confirm that LTT 3780 is a mid-M dwarf with an effective temperature of Teff = 3360 ± 51 K, a surface gravity of log g∗ = 4.81 ± 0.04 (cgs), and an iron abundance of [Fe/H] = 0.09 ± 0.16 dex, with an inferred mass of M∗ = 0.379 ± 0.016M· and a radius of R∗ = 0.382 ± 0.012R·. The ultra-short-period planet LTT 3780 b (Pb = 0.77 d) with a radius of 1.35-0.06+0.06 R·, a mass of 2.34-0.23+0.24 M·, and a bulk density of 5.24-0.81+0.94 g cm-3 joins the population of Earth-size planets with rocky, terrestrial composition. The outer planet, LTT 3780 c, with an orbital period of 12.25 d, radius of 2.42-0.10+0.10 R·, mass of 6.29-0.61+0.63 M·, and mean density of 2.45-0.37+0.44 g cm-3 belongs to the population of dense sub-Neptunes. With the two planets located on opposite sides of the radius gap, this planetary system is anexcellent target for testing planetary formation, evolution, and atmospheric models. In particular, LTT 3780 c is an ideal object for atmospheric studies with the James Webb Space Telescope (JWST). © 2020 ESO.CARMENES is an instrument for the Centro Astronomico Hispano-Aleman de Calar Alto (CAHA, Almeria, Spain). CARMENES is funded by the German Max-Planck-Gesellschaft (MPG), the Spanish Consejo Superior de Investigaciones Cientificas (CSIC), the European Union through FEDER/ERF FICTS-2011-02 funds, and the members of the CARMENES Consortium (Max-Planck-Institut fur Astronomie, Instituto de Astrofisica de Andalucia, Landessternwarte Konigstuhl, Institut de Ciencies de l'Espai, Institut fur Astrophysik Gottingen, Universidad Complutense de Madrid, Thuringer Landessternwarte Tautenburg, Instituto de Astrofisica de Canarias, Hamburger Sternwarte, Centro de Astrobiologia and Centro Astronomico Hispano-Aleman), with additional contributions by the Spanish Ministry of Economy, the German Science Foundation through the Major Research Instrumentation Programme and DFG Research Unit FOR2544 "Blue Planets around Red Stars", the Klaus Tschira Stiftung, the states of Baden-Wurttemberg and Niedersachsen, and by the Junta de Andalucia. This paper includes data collected by the TESS mission. Funding for the TESS mission is provided by the NASA Explorer Program. We acknowledge the use of public TOI Release data from pipelines at the TESS Science Office and at the TESS Science Processing Operations Center. Resources supporting this work were provided by the NASA High-End Computing (HEC) Program through the NASA Advanced Supercomputing (NAS) Division at Ames Research Center for the production of the SPOC data products. This research has made use of the Exoplanet Follow-up Observation Program website, which is operated by the California Institute of Technology, under contract with the National Aeronautics and Space Administration under the Exoplanet Exploration Program. This work has made use of data from the European Space Agency (ESA) mission Gaia (https://www.cosmos.esa.int/gaia), processed by the Gaia Data Processing and Analysis Consortium (DPAC, https://www.cosmos.esa.int/web/gaia/dpac/consortium).Funding for the DPAC has been provided by national institutions, in particular the institutions participating in the Gaia Multilateral Agreement. This article is partly based on observations made with the MuSCAT2 instrument, developed by ABC, at Telescopio Carlos Sanchez operated on the island of Tenerife by the IAC in the Spanish Observatorio del Teide. This work makes use of observations from the LCOGT network. This work makes use of observations acquired with the T150 telescope at Sierra Nevada Observatory, operated by the Instituto de Astrofisica de Andalucia (IAACSIC). Some of the Observations in the paper made use of the High-Resolution Imaging instrument 'Alopeke at Gemini-North. `Alopeke was funded by the NASA Exoplanet Exploration Program and built at the NASA Ames Research Center by Steve B. Howell, Nic Scott, Elliott P. Horch, and Emmett Quigley. IRD is operated by the Astrobiology Center of the National Institutes of Natural Sciences. The research leading to these results has received funding from the ARC grant for Concerted Research Actions, financed by the WalloniaBrussels Federation. TRAPPIST is funded by the Belgian Fund for Scientific Research (Fond National de la Recherche Scientifique, FNRS) under the grant FRFC 2.5.594.09.F, with the participation of the Swiss National Science Fundation (SNF). TRAPPIST-North is a project funded by the University of Liege (Belgium), in collaboration with Cadi Ayyad University of Marrakech (Morocco) M.G. and E.J. are F.R.S.-FNRS Senior Research Associate. The authors acknowledge funding from the Spanish Ministry of Economics and Competitiveness through projects PGC2018-098153-B-C31 and AYA2015-69350-C3-2-P. This work is partly supported by JSPS KAKENHI Grant Numbers JP18H01265 and JP18H05439, and JST PRESTO Grant Number JPMJPR1775. V.M.P. acknowledges support from NASA Grant NNX17AG24G. T.H. acknowledges support from the European Research Council under the Horizon 2020 Framework Program via the ERC Advanced Grant Origins 83 24 28. This research has been partially funded by Project No. MDM-2017-0737 Unidad de Excelencia "Maria de Maeztu" -Centro de Astrobiologia (INTA-CSIC). This research acknowledges financial support from the State Agency for Research of the Spanish MCIU through the "Center of Excellence Severo Ochoa" award to the Instituto de Astrofisica de Andalucia (SEV-2017-0709) and project AYA2016-794425

    Loop quantum gravity and light propagation

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    Within loop quantum gravity we construct a coarse-grained approximation for the Einstein-Maxwell theory that yields effective Maxwell equations in flat spacetime comprising Planck scale corrections. The corresponding Hamiltonian is defined as the expectation value of the electromagnetic term in the Einstein-Maxwell Hamiltonian constraint, regularized a la Thiemann, with respect to a would-be semiclassical state. The resulting energy dispersion relations entail Planck scale corrections to those in flat spacetime. Both the helicity dependent contribution of Gambini and Pullin [GP] and, for a value of a parameter of our approximation, that of Ellis et. al. [ELLISETAL] are recovered. The electric/magnetic asymmetry in the regularization procedure yields nonlinearities only in the magnetic sector which are briefly discussed. Observations of cosmological Gamma Ray Bursts might eventually lead to the needed accuracy to study some of these quantum gravity effects.Comment: Latex, 45 pages, shorter abstract, additional reference

    Spain: Underwater Exploration on a Narrow Continental Shelf

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    In spite of Spain’s long coastline (nearly 8000 km) and its well-established tradition in underwater archaeology, the prehistoric settlement of the continental shelf is practically unknown with very few finds. Underwater research has focused on naval archaeology and, until very recently, no attempt had been made to look for prehistoric underwater sites. In the past decade,new research projects have been launched to explore selected areas on the Cantabrian shelf and offshore of Gibraltar. This chapter summarises the currently available evidence of submerged prehistoric archaeology and the preliminary results of these new project
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