934 research outputs found

    On autonomic platform-as-a-service: characterisation and conceptual model

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    In this position paper, we envision a Platform-as-a-Service conceptual and architectural solution for large-scale and data intensive applications. Our architectural approach is based on autonomic principles, therefore, its ultimate goal is to reduce human intervention, the cost, and the perceived complexity by enabling the autonomic platform to manage such applications itself in accordance with highlevel policies. Such policies allow the platform to (i) interpret the application specifications; (ii) to map the specifications onto the target computing infrastructure, so that the applications are executed and their Quality of Service (QoS), as specified in their SLA, enforced; and, most importantly, (iii) to adapt automatically such previously established mappings when unexpected behaviours violate the expected. Such adaptations may involve modifications in the arrangement of the computational infrastructure, i.e. by re-designing a different communication network topology that dictates how computational resources interact, or even the live-migration to a different computational infrastructure. The ultimate goal of these challenges is to (de)provision computational machines, storage and networking links and their required topologies in order to supply for the application the virtualised infrastructure that better meets the SLAs. Generic architectural blueprints and principles have been provided for designing and implementing an autonomic computing system.We revisit them in order to provide a customised and specific viewfor PaaS platforms and integrate emerging paradigms such as DevOps for automate deployments, Monitoring as a Service for accurate and large-scale monitoring, or well-known formalisms such as Petri Nets for building performance models

    Análisis de los diferentes tipos de desvulcanizado en la caracterización de nuevos materiales elastoméricos formados por la mezcla de estireno butadieno-caucho natural y mezclados con neumáticos fuera de uso (GTR)

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    En este artículo se propone la creación de un nuevomaterial útil para la industria a partir de la mezcla con rodillos de dos elastómeros vírgenes al 50% (estireno-butadieno (SBR) y caucho natural (NR)) con neumáticos fuera de uso (GTR). Estos neumáticos han sido previamente desvulcanizados siguiendo diversas técnicas, las cuales serán analizadas en este artículo, para posteriormente realizarse su mezcla con el elastómero virgen SBR/NR y los aditivos correspondiente, volviéndose a vulcanizar este nuevo material con el fin de que alcance las propiedades mecánicas, térmicas y de estructura que permitan su utilización en la industria. Concretamente se han analizado tres tipos de muestras; una primera formada por el elastómero virgen (SBR/NR), una segunda añadiendo al SBR/NR, GTR en la proporción de 20 phr (parts perhundred rubber), y una tercera añadiendo al SBR/NR, GTR en la proporción de 40 phr (en los ensayos mecánicos se han utilizado más porcentajes, con el finde proporcionar mayor fiabilidad en los resultados). El GTR recibido ha sido desvulcanizado aplicando diferentes técnicas: sin desvulcanizar (dn); desvulcanizado mecánicamente (dm); desvulcanizado química y mecánicamente (dcm); y desvulcanizado mediante microondas (dmw). Todos estos compuestos han sido ensayados con diferentes pruebas; Mecánicas, de Densidad de entrecruzamiento, de Análisis Térmicogravimétrico y del Ensayo de Microscopía

    Millimetre continuum observations of comet C/2009 P1 (Garradd)

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    Little is known about the physical properties of the nuclei of Oort cloud comets. Measuring the thermal emission of a nucleus is one of the few means for deriving its size and constraining some of its thermal properties. We attempted to measure the nucleus size of the Oort cloud comet C/2009 P1 (Garradd). We used the Plateau de Bure Interferometer to measure the millimetric thermal emission of this comet at 157 GHz (1.9 mm) and 266 GHz (1.1 mm). Whereas the observations at 266 GHz were not usable due to bad atmospheric conditions, we derived a 3-sigma upper limit on the comet continuum emission of 0.41 mJy at 157 GHz. Using a thermal model for a spherical nucleus with standard thermal parameters, we found an upper limit of 5.6 km for the radius. The dust contribution to our signal is estimated to be negligible. Given the water production rates measured for this comet and our upper limit, we estimated that Garradd was very active, with an active fraction of its nucleus larger than 50%.Comment: Accepted for publication in Astronomy & Astrophysics. 5 pages, 2 figure

    Comportamiento dieléctrico de materiales compuestos reforzados con Ground Tire Rubber (GTR)

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    La masiva fabricación de neumáticos y la dificultad para su eliminación o almacenamiento constituye un grave problema medioambiental. En la actualidad, se utilizan diversos métodos para el reciclaje de neumáticos, como la trituración mecánica, en la que se separa el caucho vulcanizado del acero y las fibras, utilizándose este caucho en numerosas aplicaciones como pavimentos, aislantes, calzados, etc.Con el presente estudio se pretende dar una nueva salida a los neumáticos fuera de uso (GTR), demostrándose su utilidad como dieléctricos. Para ello, se ha combinado GTR con policloruro de vinilo (PVC), obteniendo un material compuesto de matriz polimérica reforzado con GTR. Se ha caracterizado el comportamiento dieléctrico paralas diversas mezclas del PVC con GTR (desde el 0% al 70% de GTR), en un rango de temperaturas que varía desde los 30ºC hasta los 130ºC, y con unas frecuencias desde 1·10-2 Hz, hasta 1·107 Hz. Los ensayos eléctricos han permitido el análisis de la permitividad, la resistividad, el factor de pérdidas dieléctricas y los módulos de relajación (Arrhenius). Se ha comprobado como todas estas propiedades aumentan a bajas temperaturas (30ºC). Asimismo, también se observa que la evolución de estos parámetros varía significativamente en función de la frecuencia y la temperatura

    Complex organic molecules in comets C/2012 F6 (Lemmon) and C/2013 R1 (Lovejoy): detection of ethylene glycol and formamide

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    A spectral survey in the 1 mm wavelength range was undertaken in the long-period comets C/2012 F6 (Lemmon) and C/2013 R1 (Lovejoy) using the 30 m telescope of the Institut de radioastronomie millim\'etrique (IRAM) in April and November-December 2013. We report the detection of ethylene glycol (CH2_2OH)2_2 (aGg' conformer) and formamide (NH2_2CHO) in the two comets. The abundances relative to water of ethylene glycol and formamide are 0.2-0.3% and 0.02% in the two comets, similar to the values measured in comet C/1995 O1 (Hale-Bopp). We also report the detection of HCOOH and CH3_3CHO in comet C/2013 R1 (Lovejoy), and a search for other complex species (methyl formate, glycolaldehyde).Comment: Accepted for publication as a Letter in Astronomy and Astrophysic

    Gray matter correlates of cognitive ability tests used for vocational guidance

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    <p>Abstract</p> <p>Background</p> <p>Individual differences in cognitive abilities provide information that is valuable for vocational guidance, but there is an ongoing debate about the role of ability factors, including general intelligence (<it>g</it>), compared to individual tests. Neuroimaging can help identify brain parameters that may account for individual differences in both factors and tests. Here we investigate how eight tests used in vocational guidance correlate to regional gray matter. We compare brain networks identified by using scores for ability factors (general and specific) to those identified by using individual tests to determine whether these relatively broad and narrow approaches yield similar results.</p> <p>Findings</p> <p>Using MRI and voxel-based morphometry (VBM), we correlated gray matter with independent ability factors (general intelligence, speed of reasoning, numerical, spatial, memory) and individual test scores from a battery of cognitive tests completed by 40 individuals seeking vocational guidance. Patterns of gray matter correlations differed between group ability factors and individual tests. Moreover, tests within the same factor showed qualitatively different brain correlates to some degree.</p> <p>Conclusions</p> <p>The psychometric factor structure of cognitive tests can help identify brain networks related to cognitive abilities beyond a general intelligence factor (<it>g</it>). Correlates of individual ability tests with gray matter, however, appear to have some differences from the correlates for group factors.</p

    Differential expression of voltage-gated K+ currents in medial septum/diagonal band complex neurons exhibiting distinct firing phenotypes

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    The medial septum/diagonal band complex (MSDB) controls hippocampal excitability, rhythms and plastic processes. Medial septal neuronal populations display heterogeneous firing patterns. In addition, some of these populations degenerate during age-related disorders (e.g. cholinergic neurons). Thus, it is particularly important to examine the intrinsic properties of theses neurons in order to create new agents that effectively modulate hippocampal excitability and enhance memory processes. Here, we have examined the properties of voltage-gated, K+ currents in electrophysiologically-identified neurons. These neurons were taken from young rat brain slices containing the MS/DB complex. Whole-cell, patch recordings of outward currents were obtained from slow firing, fast-spiking, regular-firing and burst-firing neurons. Slow firing neurons showed depolarization-activated K+ current peaks and densities larger than in other neuronal subtypes. Slow firing total current exhibited an inactivating A-type current component that activates at subthreshold depolarization and was reliably blocked by high concentrations of 4-AP. In addition, slow firing neurons expressed a low-threshold delayed rectifier K+ current component with slow inactivation and intermediate sensitivity to tetraethylamonium. Fast-spiking neurons exhibited the smaller IK and IA current densities. Burst and regular firing neurons displayed an intermediate firing phenotype with IK and IA current densities that were larger than the ones observed in fastspiking neurons but smaller than the ones observed in slow-firing neurons. In addition, the prevalence of each current differed among electrophysiological groups with slow firing and regular firing neurons expressing mostly IA and fast spiking and bursting neurons exhibiting mostly delayer rectifier K+ currents with only minimal contributions of the IA. The pharmacological or genetic modulations of these currents constitute an important target for the treatment of age-related disorders
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