DNS of a hot-wire anemometer in a turbulent channel flow

A body with a shape similar to a hot wire with its sheath, but no prongs, has been placed close to the wall of a turbulent channel at Re_tau = 600. The results of the channel flow, without the wire, agree with previous published ones, despite the modest resolution and domain size. A simplified, two-dimensional version of the wire at the same Reynolds number has been studied to compare the dynamic response of cold and hot wires, where a slightly bigger perturbation is seen in the hot case, but an almost identical dynamic response. The cold wire seems to be able to measure instantaneous velocity with total drag after proper calibration. Being a DNS, the complete description of the flow field around the wire is obtained

Repositorios institucionales universitarios argentinos, un acercamiento a sus colecciones

En Argentina, los repositorios institucionales se han ido incrementado en número y volumen en los últimos años, observándose que cada vez más instituciones emprenden proyectos para su implementación, sobre todo en el contexto de las universidades nacionales. Pero ¿qué contienen sus colecciones?. Si bien este asunto ya ha sido discutido en la comunidad internacional, y expuesto claramente en las guías y directrices que orientan en el tema, localmente no se ha debatido si las concepciones teóricas y los conceptos aceptados por otros países corresponden a las necesidades locales, ni tampoco se han estudiado las políticas que los repositorios mantienen en torno a su colección. Por ello, en este primer trabajo nos proponemos describir y analizar las colecciones presentes en los repositorios institucionales universitarios argentinos, específicamente su tipología documental y detectar la existencia de políticas que hacen a la conformación de cada una de éstas. Se pretende establecer un perfil de las colecciones existentes en los repositorios universitarios argentinos, para luego contrastar estos perfiles con los propuestos en la literatura internacional, promoviendo un debate local sobre las concepciones iniciales relacionadas con el movimiento de acceso abierto y la adopción en la región de los repositorios digitales como un medio para el acceso a la información (cualquiera sea su formato de presentación) y como respuesta a las necesidades y realidades locales.Fil: Unzurrunzaga, Carolina. Universidad Nacional de La Plata. Facultad de Humanidades y Ciencias de la Educación; Argentina.Fil: Borrell, Marina. Universidad Nacional de La Plata. Facultad de Humanidades y Ciencias de la Educación; Argentina.Fil: Pené, Mónica G.. Universidad Nacional de La Plata. Facultad de Humanidades y Ciencias de la Educación. Instituto de Investigaciones en Humanidades y Ciencias Sociales (UNLP-CONICET); Argentina

Improvement of CNFs/SiC nanocomposites properties obtained from different routes and consolidated by pulsed electric-current pressure sintering

The influence of the preparation route and composition on carbon nanofibers-silicon carbide (CNFs/SiC) nanocomposites' properties was studied. Nanopowders were mixed by ultrasonic dispersion or high attrition milling and the consolidation was done by pulsed electric-current pressure sintering technique. The relative density and fracture strength of high-energy attrition milled CNFs/SiC nanocomposites gradually increased with the increase of sintering temperature, from 1400 to 1800 degrees C and holding time 1 to 30 min. A chemical surface coating of CNFs with alumina precursor is proposed as a very effective way for improving the interaction between CNFs and SiC. An increase of 54% in fracture strength was achieved on the nanocomposites when the surface coating was used. As a consequence of the stronger interaction between the components, which is achieved through the use of suitable processing route and sintering parameters, and the role of nano-alumina as sintering aid improved mechanical properties was achieved. (c) 2012 Elsevier B.V. All rights reserved.This work has been carried out with the financial support of the National Plan Projects nos. MAT2006-01783 and MAT2007-30989-E and the Regional Project no. FICYT PC07-021. A. Borrell, acknowledges the Spanish Ministry of Science and Innovation for her Juan de la Cierva contract (no. JCI-2011-10498).Rocha, VG.; Borrell Tomás, MA.; Torrecillas, R.; Fernandez, A. (2012). Improvement of CNFs/SiC nanocomposites properties obtained from different routes and consolidated by pulsed electric-current pressure sintering. Materials Science and Engineering: A. 556:414-419. https://doi.org/10.1016/j.msea.2012.07.006S41441955

Análisis del infrarregistro de la mortalidad perinatal y sus factores asociados en una región sanitaria de Cataluña

ResumenObjetivosEvaluar la magnitud del infrarregistro de las muertes perinatales de la Región Sanitaria «Centre» (RSC) (Cataluña). Estimar las tasas de mortalidad reales y analizar los factores asociados al infrarregistro.MétodosEstudio observacional retrospectivo del infrarregistro de la mortalidad perinatal durante el período 1991–1992 en la RSC. Mediante una recogida activa se han identificado las muertes perinatales de peso igual o superior a 500 gr o de 22 semanas o más, ocurridas en los hospitales del RSC, comparándolas, mediante un apareamiento informático, con las muertes perinatales del registro oficial de mortalidad. Las variables de apareamiento utilizadas han sido: nombre y apellidos del recién nacido, sexo, municipio y fecha de la defunción. Se ha aplicado el análisis de regresión logística para detectar los factores asociados al infrarregistro.ResultadosLa mortalidad perinatal en la RSC en el período 1991–92 se ha infraestimado en un 34% (IC 95%: 26%–42%). La mayor parte de las muertes no declaradas corresponde a muertes fetales y/o recién nacidos de muy bajo peso o de gran prematuridad que mueren a las pocas horas de vida. Durante el fin de semana el infrarregistro es unas cuatro veces mayor. Una vez recogida, la tasa de mortalidad perinatal en la RSC para los años 1991–1992 pasa de 6,3 por 1.000 nacimientos a 9,6 por 1.000 nacimientos.ConclusionesPara disponer de una información precisa de las necesidades de salud de las mujeres en edad fértil y de los recién nacidos de la RSC, y de cada uno de sus sectores, debe mejorarse la declaración de las muertes perinatales.SummaryObjectivesTo assess the degree of undereporting of perinatal deaths in the «Centre» Region (CR) during 1991 and 1992.MethodsObservational retrospective study of the undereporting of perinatal deaths in the CR during 1991 and 1992. Perinatal deaths above 499 grams or 21 weeks of gestation which occurred in the hospitals of the CR were identified by reviewing hospital records, and then compared through linkage with perinatal deaths recorded in vital statistics. The following variables were used for the matching: name and surname, sex, county and date of death. Logistic regression was used to identify factors associated with undereporting.ResultsThe degree of undereporting of perinatal deaths in the CR during 1991–1992 was 34% [95% CI: (26%–42%)]. Most undereported perinatal deaths corresponded to fetal deaths, or very low birthweight or preterm livebirths that died shortly after birth. Over the weekend, undereporting increases by four-fold. The official perinatal mortality rate for the CR, 6.3 per 1,000 births, increased to 9.6 per 1,000 births, after taking into account undereporting.ConclusionsIn order to have valid information of the health needs of mothers and newborns reporting of perinatal deaths must be improved

LES-based Study of the Roughness Effects on the Wake of a Circular Cylinder from Subcritical to Transcritical Reynolds Numbers

This paper investigates the effects of surface roughness on the flow past a circular cylinder at subcritical to transcritical Reynolds numbers. Large eddy simulations of the flow for sand grain roughness of size k/D = 0.02 are performed (D is the cylinder diameter). Results show that surface roughness triggers the transition to turbulence in the boundary layer at all Reynolds numbers, thus leading to an early separation caused by the increased momentum deficit, especially at transcritical Reynolds numbers. Even at subcritical Reynolds numbers, boundary layer instabilities are triggered in the roughness sublayer and eventually lead to the transition to turbulence. The early separation at transcritical Reynolds numbers leads to a wake topology similar to that of the subcritical regime, resulting in an increased drag coefficient and lower Strouhal number. Turbulent statistics in the wake are also affected by roughness; the Reynolds stresses are larger due to the increased turbulent kinetic energy production in the boundary layer and separated shear layers close to the cylinder shoulders.We acknowledge “Red Española de Surpercomputación” (RES) for awarding us access to the MareNostrum III machine based in Barcelona, Spain (Ref. FI-2015-2-0026 and FI-2015-3-0011). We also acknowledge PRACE for awarding us access to Fermi and Marconi Supercomputers at Cineca, Italy (Ref. 2015133120). Oriol Lehmkuhl acknowledges a PDJ 2014 Grant by AGAUR (Generalitat de Catalunya). Ugo Piomelli acknowledges the support of the Natural Sciences and Engineering Research Council (NSERC) of Canada under the Discovery Grant Programme (Grant No. RGPIN-2016-04391). Ricard Borrell acknowledges a Juan de la Cierva postdoctoral grant (IJCI-2014-21034). Ivette Rodriguez, Oriol Lehmkuhl, Ricard Borrell and Assensi Oliva acknowledge Ministerio de Economía y Competitividad, Secretaría de Estado de Investigación, Desarrollo e Innovación, Spain (ref. ENE2014-60577-R).Peer ReviewedPostprint (author's final draft

Fin whales as bioindicators of multi-decadal change in carbon and oxygen stable isotope shifts in the North Atlantic

Global changes, and particularly the massive release of CO2 to the atmosphere and subsequent global warming, have altered the baselines of carbon and oxygen stable isotopic ratios. Temporal shifts in these baselines can be advantageously monitored through cetacean skin samples because these animals are highly mobile and therefore integrate in their tissues the heterogeneity of local environmental signals. In this study, we examine variation of delta C-13 and delta O-18 values in the skin of fin whales sampled over three decades in two different North Atlantic feeding grounds: west Iceland and northwest Spain. These locations are situated about 2700 km apart and thus represent a wide latitudinal range within the North Atlantic Ocean. The delta C-13 decrease in both areas is attributed to the burning of fossil fuels and increased deforestation worldwide, the so-called Suess effect. The dissimilarity in the magnitude of the shift between the two areas is coincidental with previous information on local shifts and lies within the ranges of variation observed. delta O-18 values experienced a minimal, yet significant change in fin whales from W Iceland (a decline of - 0.44 parts per thousand between 1986 and 2013) but not in those from NW Spain. This is in concordance with a higher rise in temperatures in the former area than in the latter. The study validates the use of cetacean skin to monitor temporal and geographical shifts in stable isotopic values and alerts that, when applying this tool to ecological research, comparisons between sample sets should take into account temporal and latitudinal scales

Heterogeneous CPU/GPU co-execution of CFD simulations on the POWER9 architecture: Application to airplane aerodynamics

High fidelity Computational Fluid Dynamics simulations are generally associated with large computing requirements, which are progressively acute with each new generation of supercomputers. However, significant research efforts are required to unlock the computing power of leading-edge systems, currently referred to as pre-Exascale systems, based on increasingly complex architectures. In this paper, we present the approach implemented in the computational mechanics code Alya. We describe in detail the parallelization strategy implemented to fully exploit the different levels of parallelism, together with a novel co-execution method for the efficient utilization of heterogeneous CPU/GPU architectures. The latter is based on a multi-code co-execution approach with a dynamic load balancing mechanism. The assessment of the performance of all the proposed strategies has been carried out for airplane simulations on the POWER9 architecture accelerated with NVIDIA Volta V100 GPUs

EPD and Spark Plasma Sintering of bimodal alumina/titania concentrated suspensions

Alumina-aluminium titanate (A-AT) composites and laminates have been recently investigated because they can provide improved flaw tolerance and toughness associated to a microcracking mechanism. A-AT composites have been produced by slip casting and reaction sintering of submicron sized alumina and titania powders. This work deals with the preparation of thick self-sustained A-AT films from mixtures of submicron sized alumina and nanosized titania powders and further sintering by conventional and non-conventional (spark plasma sintering, SPS) methods. Suspensions were prepared in water to high solid loadings, up to 50 vol.%. Self-sustained films were obtained by aqueous electrophoretic deposition (EPD) using graphite substrates under constant current density conditions. The evolution of mass per unit area with current density and deposition time was recorded. The films were characterized in the green state and after sintering at different temperatures (1300-1400) degrees C. Fully dense A-AT reaction sintered materials were obtained at low temperature by SPSThis study has been supported by the Spanish Ministry of Science and Innovation MAT2009-14369-C02-01 and MAT2009-14144-C03-02. A. Borrell, acknowledges the Spanish Ministry of Science and Innovation for her Juan de la Cierva contract (JCI-2011-10498) and the Generalitat Valenciana for the BEST/2012/302 grant and the financial support for ACOMP/2012/166.Borrell Tomás, MA.; Salvador Moya, MD.; Rocha, VG.; Fernández, A.; Molina, T.; Moreno, R. (2013). EPD and Spark Plasma Sintering of bimodal alumina/titania concentrated suspensions. Journal of Alloys and Compounds. 577:195-202. https://doi.org/10.1016/j.jallcom.2013.04.175S19520257

Patterns of variability of retinol levels in a harbour porpoise population from an unpolluted environment

Organochlorine compounds (OC) are known to induce vitamin A (retinoids) deficiency in mammals, which may be associated with impairment of immunocompetence, reproduction and growth. This makes retinoids a potentially useful biomarker of organochlorine impact on marine mammals. However, use of retinoids as a biomarker requires knowledge about its intrapopulation patterns of variation in natural conditions, information which is not currently available. We investigated these patterns in a cetacean population living in an unpolluted environment. 100 harbour porpoises Phocoena phocoena from West Greenland were sampled during the 1995 hunting season. Sex, age, morphometrics, nutritive condition, and retinol (following saponification) and OC levels in blubber were determined for each individual. OC levels found were extremely low and therefore considered unlikely to affect the population adversely: mean blubber concentrations, expressed on an extractable basis, were 2.04 (SD = 1.1) ppm for PCBs and 2.76 (SD = 1.66) ppm for tDDT. The mean blubber retinol concentration for the overall population was 59.66 (SD = 45.26) mu g g(-1). Taking into account the high contribution of blubber to body mass, blubber constitutes a significant body site for retinoid deposition in harbour porpoises. Retinol concentrations did not differ significantly between geographical regions or sexes, but they did correlate significantly (p <0.001) with age. Body condition, measured by determining the lipid content of the blubber, did not have a significant effect on retinol levels but the individuals examined were considered to be in an overall good nutritive condition. It is concluded that measurement of retinol concentrations in blubber samples is feasible and has a potential for use as a biomarker of organochlorine exposure in cetaceans. However, in order to do so, biological information, particularly age, is critical for the correct assessment of physiological impac

Anandamide inhibits Theiler's virus induced VCAM-1 in brain endothelial cells and reduces leukocyte transmigration in a model of blood brain barrier by activation of CB1 receptors

<p>Abstract</p> <p>Background</p> <p>VCAM-1 represents one of the most important adhesion molecule involved in the transmigration of blood leukocytes across the blood-brain barrier (BBB) that is an essential step in the pathogenesis of MS. Several evidences have suggested the potential therapeutic value of cannabinoids (CBs) in the treatment of MS and their experimental models. However, the effects of endocannabinoids on VCAM-1 regulation are poorly understood. In the present study we investigated the effects of anandamide (AEA) in the regulation of VCAM-1 expression induced by Theiler's virus (TMEV) infection of brain endothelial cells using <it>in vitro </it>and <it>in vivo </it>approaches.</p> <p>Methods</p> <p>i) <it>in vitro</it>: VCAM-1 was measured by ELISA in supernatants of brain endothelial cells infected with TMEV and subjected to AEA and/or cannabinoid receptors antagonist treatment. To evaluate the functional effect of VCAM-1 modulation we developed a blood brain barrier model based on a system of astrocytes and brain endothelial cells co-culture. ii) <it>in vivo</it>: CB₁receptor deficient mice (Cnr1^-/-) infected with TMEV were treated with the AEA uptake inhibitor UCM-707 for three days. VCAM-1 expression and microglial reactivity were evaluated by immunohistochemistry.</p> <p>Results</p> <p>Anandamide-induced inhibition of VCAM-1 expression in brain endothelial cell cultures was mediated by activation of CB₁receptors. The study of leukocyte transmigration confirmed the functional relevance of VCAM-1 inhibition by AEA. <it>In vivo </it>approaches also showed that the inhibition of AEA uptake reduced the expression of brain VCAM-1 in response to TMEV infection. Although a decreased expression of VCAM-1 by UCM-707 was observed in both, wild type and CB₁receptor deficient mice (Cnr1^-/-), the magnitude of VCAM-1 inhibition was significantly higher in the wild type mice. Interestingly, Cnr1^-/-mice showed enhanced microglial reactivity and VCAM-1 expression following TMEV infection, indicating that the lack of CB₁receptor exacerbated neuroinflammation.</p> <p>Conclusions</p> <p>Our results suggest that CB₁receptor dependent VCAM-1 inhibition is a novel mechanism for AEA-reduced leukocyte transmigration and contribute to a better understanding of the mechanisms underlying the beneficial role of endocannabinoid system in the Theiler's virus model of MS.</p