291 research outputs found

    Colonización espontánea de taludes de desmonte sobre margas en Navarra: establecimiento y fuente de diásporas.

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    Tras la hidrosiembra de taludes de desmonte sobre margas en localidades navarras con clima submediterráneo se implanta una cubierta vegetal de especies hidrosembradas que experimenta una rápida regresión, tal y como hemos observado en estudios previos. A pesar de ello, algunas especies autóctonas son capaces de colonizar estas superficies. Describimos la capacidad de colonización de estas últimas especies, cuyas diásporas proceden de la lluvia de semillas, para determinar si también les afecta la regresión observada en las especies hidrosembradas. También estudiamos su distribución espacial para determinar la fuente de diásporas. A pesar de la gran dificultad para colonizar los desmontes, las especies autóctonas no siguen el modelo regresivo que presentan las especies hidrosembradas en desmontes de similares características en Navarra. Por otro lado, la mayoría de las especies disminuyen su abundancia al aumentar la distancia a la zona superior del talud, donde se encuentra la vegetación que actúa como principal fuente de diásporas

    Near-Earth asteroids spectroscopic survey at Isaac Newton Telescope

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    The population of near-Earth asteroids (NEAs) shows a large variety of objects in terms of physical and dynamical properties. They are subject to planetary encounters and to strong solar wind and radiation effects. Their study is also motivated by practical reasons regarding space exploration and long-term probability of impact with the Earth. We aim to spectrally characterize a significant sample of NEAs with sizes in the range of \sim0.25 - 5.5 km (categorized as large), and search for connections between their spectral types and the orbital parameters. Optical spectra of NEAs were obtained using the Isaac Newton Telescope (INT) equipped with the IDS spectrograph. These observations are analyzed using taxonomic classification and by comparison with laboratory spectra of meteorites. A total number of 76 NEAs were observed. We classified 44 of them as Q/S-complex, 16 as B/C-complex, eight as V-types, and another eight belong to the remaining taxonomic classes. Our sample contains 27 asteroids categorized as potentially hazardous and 31 possible targets for space missions including (459872) 2014 EK24, (436724) 2011 UW158, and (67367) 2000 LY27. The spectral data corresponding to (276049) 2002 CE26 and (385186) 1994 AW1 shows the 0.7 μ\mum feature which indicates the presence of hydrated minerals on their surface. We report that Q-types have the lowest perihelia (a median value and absolute deviation of 0.797±0.2440.797\pm0.244 AU) and are systematically larger than the S-type asteroids observed in our sample. We explain these observational evidences by thermal fatigue fragmentation as the main process for the rejuvenation of NEA surfaces. In general terms, the taxonomic distribution of our sample is similar to the previous studies and matches the broad groups of the inner main belt asteroids. Nevertheless, we found a wide diversity of spectra compared to the standard taxonomic types.Comment: Accepted in Astronomy & Astrophysics (A&A

    Reducción de vibraciones en una rectificadora sin centros mediante la utilización de actuadores piezoelectricos

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    National audienceEn el presente artículo se describe la realización práctica de un sistema de reducción de vibraciones de chatter en una rectificadora sin centros, utilizando actuadores piezoeléctricos. El trabajo presentado complementa aquél de carácter teórico y generalista presentado en la pasada edición de este mismo congreso. Se describe la metodología seguida para la definición del tipo de control a utilizar y los criterios seguidos para definir la localización de los actuadores piezoeléctricos. El trabajo incluye la elaboración de un modelo para reflejar el comportamiento dinámico de la máquina para el rango de frecuencias de interés, dando así pie a la realización de distintas simulaciones que permitieron definir las características que deberían disponer los actuadores disponibles comercialmente. Se ha implementado una estrategia de control activo del amortiguamiento, utilizando controladores de realimentación proporcionales. Se presentan los resultados obtenidos en los ensayos de mecanizado una vez implantado el sistema en la máquina. Se ha conseguido un sistema que permite reducir los picos de resonancia de los modos que causan chatter, lo que causa un importante aumento del umbral de estabilidad de la máquina

    Towards an improvement in the spectral description of central stars of planetary nebulae

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    Context. There are more than 3000 known Galactic planetary nebulae, but only 492 central stars of Galactic planetary nebulae (CSPN) have known spectral types. It is vital to increase this number in order to have reliable statistics, which will lead to an increase of our understanding of these amazing objects. Aims. We aim to contribute to the knowledge of central stars of planetary nebulae and stellar evolution. Methods. This observational study is based on Gemini Multi-Object Spectrographs (GMOS) and with the Intermediate Dispersion Spectrograph (IDS) at the Isaac Newton Telescope spectra of 78 CSPN. The objects were selected because they did not have any previous classification, or the present classification is ambiguous. These new high quality spectra allowed us to identify the key stellar lines for determining spectral classification in the Morgan-Keenan (MK) system. Results. We have acquired optical spectra of a large sample of CSPN. From the observed targets, 50 are classified here for the first time while for 28 the existing classifications have been improved. In seven objects we have identified a P-Cygni profile at the He I lines. Six of these CSPN are late O-Type. The vast majority of the stars in the sample exhibit an absorption-Type spectrum, and in one case we have found wide emission lines typical of [WR] stars. We give a complementary, and preliminary, classification criterion to obtain the sub-Type of the O(H)-Type CSPN. Finally, we give a more realistic value of the proportion of CSPN that are rich or poor in hydrogen.Instituto de Astrofísica de La Plat

    An Extremely Elongated Cloud over Arsia Mons Volcano on Mars: I. Life Cycle

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    We report a previously unnoticed annually repeating phenomenon consisting of the daily formation of an extremely elongated cloud extending as far as 1800 km westward from Arsia Mons. It takes place in the Solar Longitude (Ls) range of ~220-320, around the Southern solstice. We study this Arsia Mons Elongated Cloud (AMEC) using images from different orbiters, including ESA Mars Express, NASA MAVEN, Viking 2, MRO, and ISRO Mars Orbiter Mission (MOM). We study the AMEC in detail in Martian Year (MY) 34 in terms of Local Time and Ls and find that it exhibits a very rapid daily cycle: the cloud growth starts before sunrise on the western slope of the volcano, followed by a westward expansion that lasts 2.5 hours with a velocity of around 170 m/s in the mesosphere (~45 km over the areoid). The cloud formation then ceases, it detaches from its formation point, and continues moving westward until it evaporates before the afternoon, when most sun-synchronous orbiters observe. Moreover we comparatively study observations from different years (i.e. MYs 29-34) in search of interannual variations and find that in MY33 the cloud exhibits lower activity, whilst in MY34 the beginning of its formation was delayed compared to other years, most likely due to the Global Dust Storm. This phenomenon takes place in a season known for the general lack of clouds on Mars. In this paper we focus on observations, and a theoretical interpretation will be the subject of a separate paper

    Mitochondrial Morphological and Functional Reprogramming Following CD137 (4-1BB) Costimulation.

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    T and NK lymphocytes express CD137 (4-1BB), a costimulatory receptor of the TNFR family whose function is exploitable for cancer immunotherapy. Mitochondria regulate the function and survival of T lymphocytes. Herein, we show that CD137 costimulation provided by agonist mAb and CD137L (4-1BBL) induced mitochondria enlargement that resulted in enhanced mitochondrial mass and transmembrane potential in human and mouse CD8+ T cells. Such mitochondrial changes increased T-cell respiratory capacities and were critically dependent on mitochondrial fusion protein OPA-1 expression. Mass and function of mitochondria in tumor-reactive CD8+ T cells from cancer-bearing mice were invigorated by agonist mAb to CD137, whereas mitochondrial baseline mass and function were depressed in CD137-deficient tumor reactive T cells. Tumor rejection induced by the synergistic combination of adoptive T-cell therapy and agonistic anti-CD137 was critically dependent on OPA-1 expression in transferred CD8+ T cells. Moreover, stimulation of CD137 with CD137 mAb in short-term cultures of human tumor-infiltrating lymphocytes led to mitochondria enlargement and increased transmembrane potential. Collectively, these data point to a critical link between mitochondrial morphology and function and enhanced antitumor effector activity upon CD137 costimulation of T cells. Cancer Immunol Res; 6(7); 798-811. ©2018 AACR.This project was supported by imCORE Network (Roche Genentech), MINECO (SAF2014-52361-R, 2017-83267-C2-1-R; I. Melero), European Commission VII Framework and Horizon 2020 programs (IACT and PROCROP), Fundacion de la Asociaci on Espa nola Contra el C ~ ancer (AECC), and Fundacion BBVA. A. Teijeira receives support from a Juan de la Cierva contract, MINECO. Electron and light microscopy CIMA services as well as Flow Cytometry CIMA facilities (Diego Alignani) and personnel at blood bank of Navarra are acknowledged for their technical support. We are also grateful to Drs. Lasarte and HervasStubbs for scientific discussion and to Dr. Paul Miller for editing the manuscript. The costs of publication of this article were defrayed in part by the payment of page charges. This article must therefore be hereby marked advertisement in accordance with 18 U.S.C. Section 1734 solely to indicate this fact.S

    Testu-ahots bihurketa (TAB) euskaraz gaur egun

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    En este artículo se describe la situación de la conversión de texto a voz en euskara, teniendo en cuenta tanto los problemas lingüísticos como técnicos. Después de describir las diferezites etapas del procesado lingüístico, preprocesado, transcripcióti fonética, análisis acentuar y prosódico, se contemplan las aplicaciones que puede tener esta tecnología en sistemas de información, enseñanza de idiomas, ayudas a personas discapacitadas, investigación básica de voz, investigación lingüística y en multimedia. Finalmente tras mostrar los principales problemas lingüísticos que hemos encontrado con el euskara así como las decisiones tomadas durante el desarrollo del sistema, se sugieren los próximos pasos

    Idoneidad de la prescripción antibiótica en atención primaria en la Comunidad Autónoma Vasca

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    ObjetivoEstudiar la variabilidad e idoneidad de la prescripción antibiótica en atención primaria en la Comunidad Autónoma Vasca (CAV).DiseñoEstudio descriptivo, prospectivo.EmplazamientoCentros de atención primaria de la red reformada y no reformada de la CAV.Mediciones y resultados principalesSe estudiaron 3.182 infecciones obtenidas de consultas sobre enfermedad infecciosa mediante muestreo estratificado por área sanitaria durante febrero, marzo y abril de 1998. La idoneidad de la prescripción de antibióticos (ATB) se comparó con unos patrones elaborados tras una extensa revisión bibliográfica. Un 68,6% de las consultas son infecciones que no requieren ATB (catarro de vías altas [IRA], bronquitis aguda, gripe y gastroenteritis). Se utilizan ATB en un 28,5% de estos casos (IC, 26,6-30,5). Destaca la bronquitis aguda, con un 90,7% (IC, 87,3-93,4). La prescripción innecesaria supone un 39,7% de la prescripción total antibiótica (IC, 37,2-42,1%), suponiendo un gasto anual innecesario de 1.155 millones de pesetas.En el 31,4% de las infecciones que requieren tratamiento con ATB, se opta por uno no adecuado en un 23,7% (IC, 21-26,7%).En total, la idoneidad del tratamiento global fue del 72,2% (IC, 70,6-73,8). El hecho de trabajar en la red reformada se asoció a una mejor prescripción en todos los casos. Los pediatras prescriben mejor en el caso de las infecciones no susceptibles de tratamiento con ATB.ConclusionesLa prescripción de ATB no se realiza conforme a la evidencia científica disponible. Los tratamientos incorrectos tienen lugar sobre todo en procesos benignos y autolimitados. Es necesaria una política local de uso de ATB que incluya colaboración multidisciplinaria y formación continuada efectiva.ObjectiveTo study the variability and suitability of antibiotic prescription in primary care in the Basque Country.DesignProspective, descriptive study.SettingBasque Country health care centres both within and not in the reformed network.Measurements and main results3182 infections from consultations for infectious disease were studied through sampling stratified by health area during February, March and April 1998. The appropriateness of antibiotics (ATB) prescription was compared with some standards after an extensive bibliographic review. 68.6% of consultations were infections not needing ATB (infections of respiratory airways, acute bronchitis, flu and gastro-enteritis). ATB were used in 28.5% of these cases (CI: 26.6-30.5), especially in acute bronchitis (90.7%) (CI: 87.3-93.4). Unnecessary prescription supposes 39.7% of total antibiotic prescription (CI: 37.2-42.1%), which means unnecessary annual expenditure of 1155 million pesetas. In 31.4% of the infections that require ATB treatment, in 23.7% inappropriate treatment was chosen (CI: 21-26.7%). Overall appropriateness of treatment was 72.2% (CI: 70.6-73.8). Working in the reformed system was linked to better prescription in all cases. Paediatricians prescribed better in the case of infections not susceptible to ATB treatment.ConclusionsATB prescription is not consistent with the available scientific evidence. Incorrect treatments occur especially in benign and self-limiting processes. A local policy of ATB use that includes multi-disciplinary collaboration and effective ongoing training is necessary
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