4,671 research outputs found

    Influence of phase-diversity image reconstruction techniques on circular polarization asymmetries

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    Full Stokes filter-polarimeters are key instruments for investigating the rapid evolution of magnetic structures on the solar surface. To this end, the image quality is routinely improved using a-posteriori image reconstruction methods. We analyze the robustness of circular polarization asymmetries to phase-diversity image reconstruction techniques. We use snapshots of magneto-hydrodynamical simulations carried out with different initial conditions to synthesize spectra of the magnetically sensitive Fe I line at 5250.2 A. We degrade the synthetic profiles spatially and spectrally to simulate observations with the IMaX full Stokes filter-polarimeter. We also simulate the focused/defocused pairs of images used by the phase-diversity algorithm for reconstruction and the polarimetric modulation scheme. We assume that standard optimization methods are able to infer the projection of the wavefront on the Zernike polynomials with 10% precision. We also consider the less favorable case of 25% precision. We obtain reconstructed monochromatic modulated images that are later demodulated and compared with the original maps. Although asymmetries are often difficult to define in the quiet Sun due to the complexity of the Stokes V profiles, we show how asymmetries are degraded with spatial and spectral smearing. The results indicate that, although image reconstruction techniques reduce the spatial smearing, they can modify the asymmetries of the profiles, mainly caused by the appearance of spatially-correlated noise.Comment: 10 pages, accepted for publication in A&

    Chaotic scattering with direct processes: A generalization of Poisson's kernel for non-unitary scattering matrices

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    The problem of chaotic scattering in presence of direct processes or prompt responses is mapped via a transformation to the case of scattering in absence of such processes for non-unitary scattering matrices, \tilde S. In the absence of prompt responses, \tilde S is uniformly distributed according to its invariant measure in the space of \tilde S matrices with zero average, < \tilde S > =0. In the presence of direct processes, the distribution of \tilde S is non-uniform and it is characterized by the average (\neq 0). In contrast to the case of unitary matrices S, where the invariant measures of S for chaotic scattering with and without direct processes are related through the well known Poisson kernel, here we show that for non-unitary scattering matrices the invariant measures are related by the Poisson kernel squared. Our results are relevant to situations where flux conservation is not satisfied. For example, transport experiments in chaotic systems, where gains or losses are present, like microwave chaotic cavities or graphs, and acoustic or elastic resonators.Comment: Added two appendices and references. Corrected typo

    Impact of the 'Seguro Médico Siglo XXI'medical insurance programme on neonatal and infant mortality in Mexico, 2006-14: an ecological approach to estimation

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    The ‘Seguro Medico Siglo XXI’ (SMSXXI), a universal coveragemedical insurance programme for children under 5 years of age, started in 2006 to help avoid catastrophic health expenditures in poor families without social security in Mexico. The study used information from the National Health Information System for the 2006–14 period. An ecological approach was followed with a panel of the 2457 municipalities of Mexico as the units of analysis. The outcome variables were the municipality-level neonatal mortality and infant mortality rates in population without access to social security. The programme variable was the coverage of the SMSXXI programme at the municipality level, expressed as a proportion. Demographic and economic variables defined at the municipality level were included as covariates. Impact was estimated by fitting a fixed-effects negative binomial regression model. Results reveal that the SMSXXI significantly reduced both infant and neonatSal mortality in the target population, although in a non-linear fashion, with minimum mortality levels found around the 70% coverage range. The effect is mostly given by the transition from the first quintile to the fourth quintile of coverage (<13% vs 70.5–93.7% coverage), and it is attenuated significantly at coverage levels very close to or at 100%. The observed risk reduction amounted to an estimated total of 11 358 infant deaths being avoided due to the SMSXXI during the 2006–14 period, of which 48% were neonatal. In conclusion, we found a significant impact of the SMSXXI programme on both infant mortality and neonatal mortality. An attenuation of the effect of the insurance on mortality rates at levels close to 100% coverage may reflect the saturation of health units in detriment of the quality of care

    Evidence of strong antiferromagnetic coupling between localized and itinerant electrons in ferromagnetic Sr2FeMoO6

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    Magnetic dc susceptibility (χ\chi) and electron spin resonance (ESR) measurements in the paramagnetic regime, are presented. We found a Curie-Weiss (CW) behavior for χ\chi(T) with a ferromagnetic Θ=446(5)\Theta = 446(5) K and μeff=4.72(9)μB/f.u.\mu_{eff} = 4.72(9) \mu_{B}/f.u., this being lower than that expected for either Fe3+(5.9μB)Fe^{3+}(5.9\mu_{B}) or Fe2+(4.9μB)Fe^{2+}(4.9\mu_{B}) ions. The ESR g-factor g=2.01(2)g = 2.01(2), is associated with Fe3+Fe^{3+}. We obtained an excellent description of the experiments in terms of two interacting sublattices: the localized Fe3+Fe^{3+} (3d53d^{5}) cores and the delocalized electrons. The coupled equations were solved in a mean-field approximation, assuming for the itinerant electrons a bare susceptibility independent on TT. We obtained χe0=3.7\chi_{e}^{0} = 3.7 10410^{-4} emu/mol. We show that the reduction of μeff\mu_{eff} for Fe3+Fe^{3+} arises from the strong antiferromagnetic (AFM) interaction between the two sublattices. At variance with classical ferrimagnets, we found that Θ\Theta is ferromagnetic. Within the same model, we show that the ESR spectrum can be described by Bloch-Hasegawa type equations. Bottleneck is evidenced by the absence of a gg-shift. Surprisingly, as observed in CMR manganites, no narrowing effects of the ESR linewidth is detected in spite of the presence of the strong magnetic coupling. These results provide evidence that the magnetic order in Sr2FeMoO6Sr_{2}FeMoO_{6} does not originates in superexchange interactions, but from a novel mechanism recently proposed for double perovskites

    Resultados del tratamiento antituberculoso en España por grupos de edad. Factores de riesgo para los resultados potencialmente insatisfactorios

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    [ES] En este trabajo se analizaron los factores que influyen en los resultados potencialmente insatisfactorios (RPI) del tratamiento antituberculoso por grupos de edad a partir de los casos de tuberculosis declarados a la Red Nacional de Vigilancia Epidemiológica (RENAVE) en 2012. Se consideraron RPI a los fracasos terapéuticos, traslados, defunciones, abandonos, tratamientos prolongados y desconocidos; y satisfactorios (RS) a la curación y tratamiento completo. Los casos se clasificaron en cuatro grupos de edad (0-14 años, 15-44, 45-64 y mayores de 65). Se analizó la asociación del RPI vs. RS con las variables de la declaración en cada uno de los grupos de edad, calculándose las OR crudas (ORc) y ajustadas (ORa) mediante un análisis bivariado y por regresión logística. De los 5.880 casos incluidos en el estudio el 80% tenían un RS. Por grupos de edad, los RS fueron 90, 83, 80 y 70% en los grupos de 0-14, 15-44, 45-64 y > 65 respectivamente. En adultos de 45 a 64 años los principales riesgos de RPI (p < 0,05) fueron ser hombre (ORc=1,47, ORa=1,39), tener un tratamiento previo (ORc=2,29, ORa=1,94) y ser VIH positivo (ORc=1,99, ORa=1,98), y en adultos jóvenes (15-44 años), además de los anteriores, el ser de origen extranjero (ORc=1,84, ORa=1,84). El 19% de los casos mayores de 65 años fallecieron durante el tratamiento. Es necesario mejorar el manejo de los casos VIH positivos y tratados previamente, así como el seguimiento de los casos en extranjeros. [EN] In this article the risk factors for unsuccessful completion of treatment by age group are analyzed. The source of data is tuberculosis (TB) cases reported to the Spanish Surveillance Epidemiological Network in 2012. Outcomes were classified as: successful (S: cured and treatment completed) and potentially unsuccessful (PU: failed, transferred, deaths, defaulted, still on treatment and unknown). Age groups used for the analysis were: 0-14, 15-44, 45-64 and >65 years. Bivariate (crude Odds Ratio, cOR) and multivariate analysis (adjusted Odds Ratio, aOR) by logistic regression was used to explore the association between epidemiological and clinical factors with PU as outcome variable. The study included 5,880 TB cases. Successful outcome was 80% for the total and 90, 83, 80 and 70% in 0-14, 15-44, 45-64 and >65 age groups respectively. Risk factors (

    Correlations between Background Radiation inside a Multilayer Interleaving Structure, Geomagnetic Activity, and Cosmic Radiation: A Fourth Order Cumulant-based Correlation Analysis

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    In this work, we analyzed time-series of background radiation inside a multilayer interleaving structure, geomagnetic activity and cosmic-ray activity using the Pearson correlation coefficient and a new correlation measure based on the one-dimensional component of the fourth order cumulant. The new method is proposed based on the fact that the cumulant of a random process is zero if it is of Gaussian nature. The results show that this methodology is useful for detecting correlations between the analyzed variables.Comment: 8 pages, 2 figures and 4 table

    Vigilancia epidemiológica de brotes de triquinosis en España. Temporadas 2006/07 a 2013/14

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    [ES] La triquinosis es una enfermedad zoonótica producida por nematodos del género Trichinella, que infecta al ser humano a través del consumo de carne cruda o poco cocinada, principalmente de cerdo o jabalí. En el análisis se utilizaron las siguientes fuentes de información: los brotes y los casos individualizados de triquinosis notificados a la Red Nacional de Vigilancia Epidemiológica (RENAVE) y altas por esta enfermedad del Conjunto Mínimo de Datos Básicos (RAE-CMBD), la superficie destinada a la caza en cada comunidad autónoma de los Anuarios de Estadística Forestal del Ministerio de Agricultura, Pesca y Alimentación y el número de capturas anuales de jabalí de la Federación Navarra de Caza. Se realizó un análisis descriptivo temporal y espacial de los brotes y casos de triquinosis en las temporadas 1994/95 a 2005/06. Se estudió la asociación entre el número de casos de triquinosis y la superficie de caza y el número de capturas de jabalí con el test de correlación de Spearman. Se declararon 22 brotes de triquinosis, con un total de 837 personas expuestas, 295 casos, 47 hospitalizaciones y una defunción. De los 295 casos, 155 fueron confirmados (53%), 137 fueron casos probables (46%) y 3 sospechosos (1%). De los 22 brotes, en 17 el alimento implicado fue la carne de jabalí. Los brotes se concentraron en provincias interiores y del centro de la Península. Trichinella spiralis sigue siendo el agente más frecuente, seguido de cerca por T. britovi. La enfermedad afectó más a hombres de entre 20 y 60 años, que también sufrieron más hospitalizaciones. En los últimos años se aprecia una disminución en el número de casos y brotes de triquinosis declarados en España. Las medidas de prevención deben incluir el adecuado control sanitario de los productos cárnicos del cerdo y el jabalí y el cocinado eficaz de la carne, que debe alcanzar al menos 65 ºC en el centro de la pieza durante un minuto como mínimo. [EN] Trichinosis is a zoonotic disease caused by nematodes of the genus Trichinella, which infects humans through the consumption of raw or undercooked meat, mainly pork or wild boar. Five different sources of information were used in the analysis. The registry of reported outbreaks, the registry of cases notified to the National Epidemiological Surveillance Network (RENAVE), and the cases coded as trichinosis in the National Hospital Discharge Registry (RAE-CMBD), the area destined for hunting in each Autonomous Community of the Forestry Statistics Yearbooks of the Ministry of Agriculture, Fisheries and Food, and the number of annual catches of wild boar of the Navarra Hunting Federation. A temporal and spatial descriptive analysis of the outbreaks and cases of trichinosis was carried out in the seasons 1994/95 to 2005/06. The association between the number of cases of trichinosis and the hunting surface and the number of wild boar captures was studied with the Spearman correlation test. 22 outbreaks of trichinosis were reported, with a total of 837 people e exposed, 295 cases, 47 hospitalizations and 1 death. Of the 295 cases, 155 were confirmed (53%), 137 were probable cases (46%) and 3 possible cases (1%). Of the 22 outbreaks, in 17 the food involved was wild boar meat. The outbreaks were concentrated in the centre of the Peninsula. Trichinella spiralis remains the most frequent agent, followed closely by T. britovi. Men between 20 and 60 years, were more affected and suffered more hospitalizations. In recent years, there has been a decrease in the number of cases and outbreaks of trichinosis notified in Spain. Prevention measures should include adequate sanitary control of pork and wild boar meat products and effective cooking of meat, which must reach at least 5 ºC in the centre of the piece for at least one minute

    Spanish ATLAS tier-2: Facing up to LHC Run 2

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    The goal of this work is to describe the way of addressing the main challenges of Run 2 by the Spanish ATLAS Tier-2. The considerable increase of energy and luminosity for the upcoming Run 2 with respect to Run 1 has led to a revision of the ATLAS computing model as well as some of the main ATLAS computing tools. In this paper, the adaptation to these changes will be described. The Spanish ATLAS Tier-2 is a R&D project which consists of a distributed infrastructure composed of three sites and its members are involved in ATLAS computing progress, namely the work in different tasks and the development of new tools (e.g. Event Index)This work has been supported by MINECO, Spain (Proj. Ref. FPA2010-21919-C03-01,02,03 & FPA2013-47424-C3,01,02,03), which include FEDER funds from the European Unio

    On the fraction of dark matter in charged massive particles (CHAMPs)

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    From various cosmological, astrophysical and terrestrial requirements, we derive conservative upper bounds on the present-day fraction of the mass of the Galactic dark matter (DM) halo in charged massive particles (CHAMPs). If dark matter particles are neutral but decay lately into CHAMPs, the lack of detection of heavy hydrogen in sea water and the vertical pressure equilibrium in the Galactic disc turn out to put the most stringent bounds. Adopting very conservative assumptions about the recoiling velocity of CHAMPs in the decay and on the decay energy deposited in baryonic gas, we find that the lifetime for decaying neutral DM must be > (0.9-3.4)x 10^3 Gyr. Even assuming the gyroradii of CHAMPs in the Galactic magnetic field are too small for halo CHAMPs to reach Earth, the present-day fraction of the mass of the Galactic halo in CHAMPs should be < (0.4-1.4)x 10^{-2}. We show that redistributing the DM through the coupling between CHAMPs and the ubiquitous magnetic fields cannot be a solution to the cuspy halo problem in dwarf galaxies.Comment: 21 pages, 2 figures. To appear in JCA
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