82 research outputs found

    First measurement of the 94Nb(n,γ) cross section at the CERN n_TOF facility

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    One of the crucial ingredients for the improvement of stellar models is the accurate knowledge of neutron capture cross-sections for the different isotopes involved in the s-,r- and i- processes. These measurements can shed light on existing discrepancies between observed and predicted isotopic abundances and help to constrain the physical conditions where these reactions take place along different stages of stellar evolution. In the particular case of the radioactive 94Nb, the 94Nb(n,γ) cross-section could play a role in the determination of the s-process production of 94Mo in AGB stars, which presently cannot be reproduced by state-of-the-art stellar models. There are no previous 94Nb(n,γ) experimental data for the resolved and unresolved resonance regions mainly due to the difficulties in producing highquality samples and also due to limitations in conventional detection systems commonly used in time-of-flight experiments. Motivated by this situation, a first measurement of the 94Nb(n,γ) reaction was carried out at CERN n_TOF, thereby exploiting the high luminosity of the EAR2 area in combination with a new detection system of small-volume C6D6-detectors and a high quality 94Nb-sample. The latter was based on hyper-pure 93Nb material activated at the high-flux reactor of ILL-Grenoble. An innovative ring-configuration detection system in close geometry around the capture sample allowed us to significantly enhance the signal-to-background ratio. This set-up was supplemented with two conventional C6D6-detectors and a highresolution LaCl3(Ce)-detector, which will be employed for addressing reliably systematic effects and uncertainties. At the current status of the data analysis, 18 resonance in 94Nb+n have been observed for the first time in the neutron energy range from thermal up to 10 keV.European Research Council (ERC)European Union’s Horizon 2020 research and innovation programme (ERC Consolidator Grant project HYMNS, with grant agreement No. 681740)ICJ220-045122-IMCIN/AEI/ 10.13039/501100011033European Union NextGenerationEU/PRTRSpanish Ministerio de Ciencia e Innovación under grants PID2019-104714GB-C21, FPA2017-83946-C2-1-P, FIS2015-71688-ERCCSICPIE-201750I2

    Recent results in nuclear astrophysics at the n_TOF facility at CERN

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    The neutron time of flight (n_TOF) facility at CERN is a spallation source characterized by a white neutron spectrum. The innovative features of the facility, in the two experimental areas, (20 m and 185 m), allow for an accurate determination of the neutron cross section for radioactive samples or for isotopes with small neutron capture cross section, of interest for Nuclear Astrophysics. The recent results obtained at n_TOF facility are presented

    Evaluación del índice de vulnerabilidad costera en la Manga del Mar Menor (Murcia, España)

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    © 2020. Universidad Complutense de Madrid . This document is made available under the CC-BY 4.0 license http://creativecommons.org/licenses/by /4.0/ This document is the published version of a published Work that appeared in final form in Anales de Geografía de la Universidad Complutense. To access the final edited and published work see https://doi.org/10.5209/aguc.72979Uno de los efectos más visibles del Cambio Climático es la subida del nivel del mar por el derretimiento de las masas de hielo terrestre. Para calcular la vulnerabilidad costera de la Manga del Mar Menor por la subida del nivel del mar, se ha aplicado el Índice de Vulnerabilidad Costera utilizando las variables geomorfología, pendiente de la costa, cambios en el nivel del mar, erosión costera, rango mareal, oleaje y una variable ambiental. El resultado refleja que tramos de playas de arena y las estructuras artificiales presentan mayor vulnerabilidad a los riesgos climáticos que aquellos tramos rocosos, por lo que se considera necesario la adecuación de sistemas duna-playa con vegetación natural bien conservada que constituyan una barrera frente a la energía de los temporales.- One of the most visible effects of Climate Change is the rise of sea levels by melting land ice masses. To calculate the coastal vulnerability of the Lower Sea Sleeve by sea level rise, the Coastal Vulnerability Index has been applied using geomorphology, coastal slope, sea level changes, coastal erosion, tidal range, swell and an environmental variable. The result reflects that stretches of sandy beaches and artificial structures are more vulnerable to climate risks than those rocky sections, so it is considered necessary to adapt dune-beach systems with natural vegetation well preserved that constitute a barrier to the energy of the storms.- L'un des effets les plus visibles du changement climatique est l'élévation du niveau de la mer due à la fonte des masses de glace terrestre. Pour calculer la vulnérabilité côtière de Manga del Mar Menor en raison de l'élévation du niveau de la mer, l'indice de vulnérabilité côtière a été appliqué en utilisant les variables de géomorphologie, la pente de la côte, les changements du niveau de la mer, l'érosion côtière, l'amplitude des marées, vagues et une variable environnementale. Le résultat reflète que les étendues de plages de sable et les structures artificielles sont plus vulnérables aux risques climatiques que ces étendues rocheuses, il est donc jugé nécessaire d'adapter les systèmes de dunes-plages avec une végétation naturelle bien préservée qui constitue une barrière contre la l'énergie des tempêtes

    Cross section measurements of 155,157Gd(n, γ) induced by thermal and epithermal neutrons

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    Neutron capture cross section measurements on 155Gd and 157Gd were performed using the time-of-flight technique at the n_TOF facility at CERN on isotopically enriched samples. The measurements were carried out in the n_TOF experimental area EAR1, at 185 m from the neutron source, with an array of 4 C6D6 liquid scintillation detectors. At a neutron kinetic energy of 0.0253 eV, capture cross sections of 62.2(2.2) and 239.8(8.4) kilobarn have been derived for 155Gd and 157Gd, respectively, with up to 6% deviation relative to values presently reported in nuclear data libraries, but consistent with those values within 1.6 standard deviations. A resonance shape analysis has been performed in the resolved resonance region up to 181 eV and 307 eV, respectively for 155Gd and 157Gd, where on average, resonance parameters have been found in good agreement with evaluations. Above these energies and up to 1 keV, the observed resonance-like structure of the cross section has been analysed and characterised. From a statistical analysis of the observed neutron resonances we deduced: neutron strength function of 2. 01 (28) × 10 - 4 and 2. 17 (41) × 10 - 4; average total radiative width of 106.8(14) meV and 101.1(20) meV and s-wave resonance spacing 1.6(2) eV and 4.8(5) eV for n + 155Gd and n + 157Gd systems, respectively.European Atomic Energy Community (Euratom) 605203Ministerio de Economía y Competitividad FPA2014-52823-C2-1-

    Neutron capture measurements with high efficiency detectors and the Pulse Height Weighting Technique

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    Neutron capture cross section measurements in time-of-flight facilities are usually performed by detecting the prompt γ-rays emitted in the capture reactions. One of the difficulties to be addressed in these measurements is that the emitted γ-rays may change with the neutron energy, and therefore also the detection efficiency. To deal with this situation, many measurements use the so called Total Energy Detection (TED) technique, usually in combination with the Pulse Height Weighting Technique (PHWT). With it, it is sought that the detection efficiency depends only on the total energy of the γ-ray cascade, which does not vary much with the neutron energy. This technique was developed in the 1960s and has been used in many neutron capture experiments to date. One of the requirements of the technique is that γ-ray detectors have a low efficiency. This has meant that the PHWT has been used with experimental setups with low detection efficiencies. However, this condition does not have to be fulfilled by the experimental system as a whole. The main goal of this work is to show that it is possible to measure with a high efficiency detection system that uses the PHWT, and how to analyze the measured data.This work was supported in part by the I+D+i grant PGC2018- 096717-B-C21 funded by MCIN/AEI/10.13039/501100011033 and by the European Commission H2020 Framework Programme project SANDA (Grant agreement ID: 847552)

    Actions for the Conservation and Restoration of the Dunes and Wetlands in the Salinas of San Pedro del Pinatar: LIFE-Salinas Project (Murcia, Southeast of Spain)

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    © 2022 by the authors. Licensee MDPI, Basel, Switzerland. This article is an open access article distributed under the terms and conditions of the Creative Commons Attribution (CC BY) license (https:// creativecommons.org/licenses/by/ 4.0/).The LIFE SALINAS project, co-financed by the European Union, aims for the conservation and improvement of the protected area named the Regional Park of Las Salinas and Arenales de San Pedro del Pinatar (Region of Murcia, Spain). The main objectives are, among others, to stop the erosion of the dunes in front of a 500 m long beach and to expand the breeding habitat of aquatic birds. Between the dune and the beach, a barrier was placed to protect the dune from the effects of storms. The dunes were fenced, placed with sand traps and revegetation was carried out with native species in the most degraded areas. Within the salt pans, 1800 m of new sandy dikes were built to separate the salt ponds. The results have been the recovery of the dune ecosystem and the increase in the population of nesting aquatic birds and other species, as well as an increase in the quality and production of salt

    Differential association between S100A4 levels and insulin resistance in prepubertal children and adult subjects with clinically severe obesity

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    Objectives: S100A4 has been recently identified as an adipokine associated with insulin resistance (IR) in adult subjects with obesity. However, no data about its levels in children with obesity and only a few approaches regarding its potential mechanism of action have been reported. To obtain a deeper understanding of the role of S100A4 in obesity, (a) S100A4 levels were measured in prepubertal children and adult subjects with and without obesity and studied the relationship with IR and (b) the effects of S100A4 in cultured human adipocytes and vascular smooth muscle cells (VSMCs) were determined. Methods: Sixty-five children (50 with obesity, age 9.0 ±1.1 years and 15 normal weight, age 8.4 ±0.8 years) and fifty-nine adults (43 with severe obesity, age 46 ±11 years and 16 normal weight, age 45 ±9 years) were included. Blood from children and adults and adipose tissue samples from adults were obtained and analysed. Human adipocytes and VSMC were incubated with S100A4 to evaluate their response to this adipokine. Results: Circulating S100A4 levels were increased in both children (P =.002) and adults (P <.001) with obesity compared with their normal-weight controls. In subjects with obesity, S100A4 levels were associated with homeostatic model assessment-insulin resistance (HOMA-IR) in adults (βstd =.42, P =.008) but not in children (βstd =.12, P =.356). Human adipocytes were not sensitive to S100A4, while incubation with this adipokine significantly reduced inflammatory markers in VSMC. Conclusions: Our human data demonstrate that higher S100A4 levels are a marker of IR in adults with obesity but not in prepubertal children. Furthermore, the in vitro results suggest that S100A4 might exert an anti-inflammatory effect. Further studies will be necessary to determine whether S100A4 can be a therapeutic target for obesity

    Atención de la urgencia quirúrgica durante la pandemia COVID-19. Recomendaciones de la Asociación Española de Cirujanos

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    La infección por el nuevo coronavirus SARS-CoV-2 (enfermedad por coronavirus 2019 [COVID-19]) ha determinado la necesidad de la reorganización de muchos centros hospitalarios en el mundo. España, como uno de los epicentros de la enfermedad, ha debido asumir cambios en la práctica totalidad de su territorio. Sin embargo, y desde el inicio de la pandemia, en todos los centros que atienden urgencias quirúrgicas ha sido necesario el mantenimiento de su cobertura, aunque igualmente ha sido inevitable introducir directrices especiales de ajuste al nuevo escenario que permitan el mantenimiento de la excelencia en la calidad asistencial. Este documento desarrolla una serie de indicaciones generales para la cirugía de urgencias y la atención al politraumatizado desarrolladas desde la literatura disponible y consensuadas por un subgrupo de profesionales desde el grupo general Cirugía-AEC-COVID-19. Estas medidas van encaminadas a contemplar un riguroso control de la exposición en pacientes y profesionales, a tener en cuenta las implicaciones de la pandemia sobre diferentes escenarios perioperatorios relacionados con la urgencia y a una adaptación ajustada a la situación del centro en relación con la atención a pacientes infectados. New coronavirus SARS-CoV-2 infection (coronavirus disease 2019 [COVID-19]) has determined the necessity of reorganization in many centers all over the world. Spain, as an epicenter of the disease, has been forced to assume health policy changes in all the territory. However, and from the beginning of the pandemic, every center attending surgical urgencies had to guarantee the continuous coverage adopting correct measures to maintain the excellence of quality of care. This document resumes general guidelines for emergency surgery and trauma care, obtained from the available bibliography and evaluated by a subgroup of professionals designated from the general group of investigators Cirugía-AEC-COVID-19 from the Spanish Association of Surgeons, directed to minimize professional exposure, to contemplate pandemic implications over different urgent perioperative scenarios and to adjust decision making to the occupational pressure caused by COVID-19 patients
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