1,464 research outputs found

    Comprehensive transient-state study for CARMENES-NIR high thermal stability

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    CARMENES has been proposed as a next-generation instrument for the 3.5m Calar Alto Telescope. Its objective is finding habitable exoplanets around M dwarfs through radial velocity measurements (m/s level) in the near-infrared. Consequently, the NIR spectrograph is highly constraint regarding thermal/mechanical requirements. As a first approach, the thermal stability has been limited to \pm 0.01K (within year period) over a working temperature of 243K. This can be achieved by means of several temperature-controlled rooms. The options considered to minimise the complexity of the thermal design are here presented, as well as the transient-state thermal analyses realised to make the best choice

    Photoelectric Properties of MOS-like Structures with Twofold SRO Films

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    AbstractThe optical properties of silicon rich oxide (SRO) have been deeply studied because, between other reasons, they emit an intense photoluminescence (PL) from visible to the near infrared range when excited with UV light. MOS-like structures with SRO film as the active layer have shown an enhanced conductivity under different illumination conditions. In this paper, MOS-like structures with double SRO layer were fabricated in order to have a barrier to isolate the silicon substrate from the active SRO layer. Results show that all structures have a higher current when light shines on them than that obtained under dark conditions. A possible application of this photo-effect can be used to increase the response of photodetectors and silicon solar cells

    Suckling, male effect and kisspeptin in the reproductive management of ewes in postpartum anestrus

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    Objective: To describe the management strategies of controlled suckling and the male effect to reduce postpartum anestrus, and to show the participation of kisspeptin to regulate the effect of both factors. Design/Methodology/Approach: A review of scientific publications was conducted, in order to show the importance of suckling and the male effect as strategies to reduce postpartum anestrus in the ewe, as well as the relation of kisspeptin with both factors. Results: Seasonal anestrus can be avoided with the use of breeds adapted to the local environment, such as Pelibuey. Postpartum anestrus occurs mainly as a result of suckling, since the latter inhibits the pulsating secretion of the gonadotropin-releasing hormone (GnRH) and the luteinizing hormone (LH). The exact path of this inhibition is unknown, although it seems that endogenous opioid peptides and kisspeptin are intermediaries. Controlled suckling and the male effect are management strategies that improve the reproductive behavior of postpartum ewes. Kisspeptin regulates the influence of the male effect through the secretion of GnRH/LH. Study Limitations/Implications: To understand the impacts of suckling and the male effect on the duration of postpartum anestrus, as well as the participation of kisspeptin in the regulation of both effects, will allow designing management strategies to improve the reproductive efficiency of the ewes. Findings/Conclusions: Controlled suckling and the male effect reduce postpartum anestrus and improve the reproductive behavior of the ewes; advancing knowledge of the kisspeptin effect could improve the effectiveness of both techniques

    An 8-mm diameter fibre robot positioner for massive spectroscopy surveys

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    This article has been accepted for publication in Monthly Notices of Royal Astronomical Society © 2015 The Authors. Published by Oxford University Press on behalf of the Royal Astronomical Society. All rights reservedMassive spectroscopic survey are becoming trendy in astrophysics and cosmology, as they can address new fundamental knowledge such as understanding the formation of the Milky Way and probing the nature of the mysterious dark energy. To enable massive spectroscopic surveys, new technology has been developed to place thousands of optical fibres at a given position on a focal plane. This technology needs to be: (1) accurate, with micrometer positional accuracy; (2) fast to minimize overhead; (3) robust to minimize failure; and (4) low cost. In this paper, we present the development, properties, and performance of a new single 8-mm in diameter fibre positioner robot, using two 4-mm DC-brushless gearmotors, that allows us to achieve accuracies up to 0.07 arcsec (5 μm). This device has been developed in the context of the Dark Energy Spectroscopic InstrumentWe acknowledge support from the Spanish MICINNs Consolider-Ingenio 2010 Program me under grant MultiDark CSD2009-00064, HEPHACOS S2009/ESP-1473, and MINECO Centro de Excelencia Severo Ochoa Programme under grant SEV-2012-0249. We also thank the support from a CSIC-AVS contract through MICINN grant AYA2010-21231-C02- 01, and CDTI grant IDC-20101033; and support from the Spanish MINECO research grants AYA2012-31101 and FPA2012-34694. JPK, PH and LM acknowledge support from the ERC advanced grant LIDA and from an SNF Interdisciplinary grant

    An 8-mm diameter fibre robot positioner for massive spectroscopy surveys

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    Massive spectroscopic survey are becoming trendy in astrophysics and cosmology, as they can address new fundamental knowledge such as understanding the formation of the Milky Way and probing the nature of the mysterious dark energy. To enable massive spectroscopic surveys, new technology has been developed to place thousands of optical fibres at a given position on a focal plane. This technology needs to be: (1) accurate, with micrometer positional accuracy; (2) fast to minimize overhead; (3) robust to minimize failure; and (4) low cost. In this paper, we present the development, properties, and performance of a new single 8-mm in diameter fibre positioner robot, using two 4-mm DC-brushless gearmotors, that allows us to achieve accuracies up to 0.07arcsec (5 μm). This device has been developed in the context of the Dark Energy Spectroscopic Instrument.

    Revisiting the epidemiology of bloodstream infections and healthcare-associated episodes: results from a multicentre prospective cohort in Spain (PRO-BAC Study)

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    PROBAC REIPI/GEIH-SEIMC/SAEI Group.The epidemiology of bloodstream infections (BSIs) is dynamic as it depends on microbiological, host and healthcare system factors. The aim of this study was to update the information regarding the epidemiology of BSIs in Spain considering the type of acquisition. An observational, prospective cohort study in 26 Spanish hospitals from October 2016 through March 2017 including all episodes of BSI in adults was performed. Bivariate analyses stratified by type of acquisition were performed. Multivariate analyses were performed by logistic regression. Overall, 6345 BSI episodes were included; 2510 (39.8%) were community-acquired (CA), 1661 (26.3%) were healthcare-associated (HCA) and 2056 (32.6%) hospital-acquired (HA). The 30-day mortality rates were 11.6%, 19.5% and 22.0%, respectively. The median age of patients was 71 years (interquartile range 60–81 years) and 3656 (58.3%; 95% confidence interval 57.1–59.6%) occurred in males. The proportions according to patient sex varied according to age strata. Escherichia coli (43.8%), Klebsiella spp. (8.9%), Staphylococcus aureus (8.9%) and coagulase-negative staphylococci (7.4%) were the most frequent pathogens. Multivariate analyses confirmed important differences between CA and HCA episodes, but also between HCA and HA episodes, in demographics, underlying conditions and aetiology. In conclusion, we have updated the epidemiological information regarding patients’ profiles, underlying conditions, frequency of acquisition types and aetiological agents of BSI in Spain. HCA is confirmed as a distinct type of acquisition.This work was financed by grants from Plan Nacional de I+D+i 2013–2016, Instituto de Salud Carlos III, Subdirección General de Redes y Centros de Investigación Cooperativa, Ministerio de Ciencia, Innovación y Universidades [PI16/01432] and the Spanish Network for Research in Infectious Diseases (REIPI) [RD16/0016/0001; RD16/0016/0008], co‐financed by the European Development Regional Fund ‘A way to achieve Europe’, Operative program Intelligent Growth 2014–2020

    Overview of IFMIF-DONES diagnostics: Requirements and techniques

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    The IFMIF-DONES Facility is a unique first-class scientific infrastructure whose construction is foreseen in Granada, Spain, in the coming years. Strong integration efforts are being made at the current project phase aiming at harmonizing the ongoing design of the different and complex Systems of the facility. The consolidation of the Diagnostics and Instrumentation, transversal across many of them, is a key element of this purpose. A top-down strategy is proposed for a systematic Diagnostics Review and Requirement definition, putting emphasis in the one-of-a-kind instruments necessary by the operational particularities of some of the Systems, as well as to the harsh environment that they shall survive. In addition, other transversal aspects such as the ones related to Safety and Machine Protection and their respective requirements shall be also considered. The goal is therefore to advance further and solidly in the respective designs, identify problems in advance, and steer the Diagnostics development and validation campaigns that will be required. The present work provides an overview of this integration strategy as well as a description of some of the most challenging Diagnostics and Instruments within the facility, including several proposed techniques currently under study

    Ciudad-territorio sustentable. Procesos, actores y estructuras

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    En los últimos años, los estudios urbanos especializados insisten en que los procesos de urbanización por los que atraviesan los distintos países desarrollados, parecen dejar atrás las explicaciones de la urbanización industrial, han surgido otras construcciones y perspectivas unas más acabadas que otras (Indovina, 1998, la “ciudad difusa”; Dematteis 1998, ciudad sin centros; Nel-lo, 1998 ciudad sin confines, Soja, 2008, la exópolis). En suma se dice que se avanza hacia la urbanización generalizada, ello acaba con la larga trayectoria del funcionamiento y naturaleza de la ciudad moderna, el cambio urbano estructural actual, es nuevamente, consecuencia de la descentralización, difusión, redistribución del desarrollo, del crecimiento y las innovaciones ahora sobre una estructura en el territorio. Ha sido una mutación no sólo empírica sino que ha dado lugar a la confrontación teórica. El sistema urbano jerárquico ha reducido su valor interpretativo porque se han modificado los supuestos en los que se basaban las relaciones de dominio y dependencia de los centros principales, porque se han abaratado los costos de transporte y el efecto de la distancia ya no es una limitante absoluta, ahora los procesos productivos flexibles y descentralizados propician las relaciones técnicas horizontales con lo cual se consiguen economías de escala externas e internas a las empresas en un territorio ampliado y no sólo exclusivamente en la aglomeración económica (Precedo, 2003; Veltz, 1999; Boix, 2002; Camagni, 2005; De Santiago, 2008 y; Garmendia, 2010).El objetivo es examinar dentro de la descentralización del proceso urbano a la ciudad-territorio en América Latina, en particular en México. En contextos urbanos desarrollados se afirma la convergencia urbana con la apertura de las unidades funcionales de los sistemas urbanos donde operan redes e interrelaciones de desarrollo cualitativo en el territorio. América Latina registra evidencias empíricas poco claras, existe alta concentración de aquella economía que contribuye al crecimiento nacional, mientras la población se descentraliza rápidamente. México, es un caso de primacía urbana histórica aunque da paso a la formación de regiones urbanas, mismas que reproducen relaciones polarizadas y escasamente descentralizadas. De manera que, en tanto domine la concentración espacial económica, la ciudadterritorio se podrá presentar en el continente sólo con algunos rasgos en regiones urbanas con mayor desarrollo y crecimiento. Palabras claves: descentralización urbana, sistema urbano, ciudad-territorio
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