2,506 research outputs found

    Impact of Power Allocation and Antenna Directivity in the Capacity of a Multiuser Cognitive Ad Hoc Network

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    This paper studies the benefits that power control and antenna directivity can bring to the capacity of a multiuser cognitive radio network. The main objective is to optimize the secondary network sum rate under the capacity constraint of the primary network. Exploiting location awareness, antenna directivity, and the power control capability, the cognitive radio ad hoc network can broaden its coverage and improve capacity. Computer simulations show that by employing the proposed method the system performance is significantly enhanced compared to conventional fixed power allocation

    Aborto epidémico y endémico asociado a la infección por Neospora caninum en el ganado bovino: relación entre la respuesta inmune y las consecuencias de la infección a lo largo de la gestación

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    Neospora caninum es un protozoo intracelular obligado perteneciente al Phylum Apicomplexa. La neosporosis bovina se considera una de las principales causas de fallo reproductivo en el ganado bovino. La transmisión transplacentaria del parásito puede originar aborto ó el nacimiento de terneros congénitamente infectados. La transmisión transplacentaria endógena ocurre tras la recrudescencia de una infección crónica en la hembra durante la gestación, mientras que la exógena se da tras una primoinfección adquirida de forma postnatal. Un mayor conocimiento de la epidemiología, integrado con el empleo de adecuadas técnicas de diagnóstico serológico son la base del control. El objetivo del presente estudio fue determinar mediante diferentes pruebas diagnósticas la relación existente entre la respuesta serológica desarrollada por reproductoras bovinas infectadas a lo largo de una gestación, el origen de la infección y sus repercusiones reproductivas.Neospora caninum is an apicomplexan protozoan parasite. At present bovine neosporosis is one of the main causes of reproductive failure in cattle worldwide. Transplacental transmission of the parasite can lead to abortion or birth of congenitally infected calves. Endogenous transplacental transmission occurs as a consequence of the recrudescence of a previous chronic infection in the cow during gestation. On the other hand, exogenous transplacental transmission occurs after an acquired postnatal primo infection. Control programmes are based on updated knowledge about the epidemiology together with the employment of appropriate diagnostic serological tests. The aim of the present study was to determine the relationship between the serologic response developed by infected breeding cattle along gestation, the mode of transmission and the future consequences in reproduction

    Compact full ku-band triplexer with improved e-plane power divider

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    An improved E-plane power divider for compact waveguide triplexers with large separation between channels is presented. The configuration of the divider aims to exploit the different behavior of the device for frequency bands with large separation, leading to a very asymmetric E-plane junction. H-plane filters with inductive windows are used for each channel, in order to obtain reduced insertion losses and lower sensitivity than in metal-insert E-plane filters. The resultant triplexer configuration is very compact, and its design is analyzed and optimized by Mode-Matching. The experimental results of a full Ku-band prototype for communications satellite systems show a very good agreement with the expected simulated response

    Un estudi sobre interdisciplinarietat, professions socials i acció socioeducativa

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    Aquest article és el relat d'un seguit d'accions encetades per donar resposta a una serie de preguntes referides a l'àmbit de la intervenció socioeducativa. El que volíem era conèixer I'estat de la interdisciplinarietat en I'àmbit de les accions socioeducatives professionals. En quin grau i de quina manera conflueixen les diferents disc iplines en I'acció social o socioeducativa? Quines professions i professionals d'alló social van desenvolupant aquestes accions? Quines relacions -de col·laboració; de confrontació; d'aïllament, etc.- es produeixen entre elles? I, per últim, ens preguntàvem: existeix una consciència entre els i les professionals sobre la necessitat -o no- d'aquesta interdisciplinarietat

    Characterization of multiple sclerosis lesions with distinct clinical correlates through quantitative diffusion MRI

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    Diffusion magnetic resonance imaging can reveal quantitative information about the tissue changes in multiple sclerosis. The recently developed multi-compartment spherical mean technique can map different microscopic properties based only on local diffusion signals, and it may provide specific information on the underlying microstructural modifications that arise in multiple sclerosis. Given that the lesions in multiple sclerosis may reflect different degrees of damage, we hypothesized that quantitative diffusion maps may help characterize the severity of lesions "in vivo" and correlate these to an individual's clinical profile. We evaluated this in a cohort of 59 multiple sclerosis patients (62% female, mean age 44.7 years), for whom demographic and disease information was obtained, and who underwent a comprehensive physical and cognitive evaluation. The magnetic resonance imaging protocol included conventional sequences to define focal lesions, and multi-shell diffusion imaging was used with b-values of 1000, 2000 and 3000 s/mm2 in 180 encoding directions. Quantitative diffusion properties on a macro- and micro-scale were used to discriminate distinct types of lesions through a k-means clustering algorithm, and the number and volume of those lesion types were correlated with parameters of the disease. The combination of diffusion tensor imaging metrics (fractional anisotropy and radial diffusivity) and multi-compartment spherical mean technique values (microscopic fractional anisotropy and intra-neurite volume fraction) differentiated two type of lesions, with a prediction strength of 0.931. The B-type lesions had larger diffusion changes compared to the A-type lesions, irrespective of their location (P < 0.001). The number of A and B type lesions was similar, although in juxtacortical areas B-type lesions predominated (60%, P < 0.001). Also, the percentage of B-type lesion volume was higher (64%, P < 0.001), indicating that these lesions were larger. The number and volume of B-type lesions was related to the severity of disease evolution, clinical disability and cognitive decline (P = 0.004, Bonferroni correction). Specifically, more and larger B-type lesions were correlated with a worse Multiple Sclerosis Severity Score, cerebellar function and cognitive performance. Thus, by combining several microscopic and macroscopic diffusion properties, the severity of damage within focal lesions can be characterized, further contributing to our understanding of the mechanisms that drive disease evolution. Accordingly, the classification of lesion types has the potential to permit more specific and better-targeted treatment of patients with multiple sclerosis

    Emissions from mechanically-biologically treated waste landfills at field scale

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    Modern waste management tends towards greater sustainability in landfilling, with the implementation of strategies such as the pretreatment of solid waste. This work assesses the behaviour of rejects from a refining stage of mechanically-biologically treated municipal solid waste at the landfill. The main results of 18 months' monitoring of an experimental pilot cell with waste from a full-scale plant are presented. This first stages are expected to be the most problematic period for this type of waste. The evolution of the temperature and the composition of leachate and gas at various points within the cell are included. During the first weeks, pollutant concentrations in the leachate exceeded the reference ranges in the literature, coinciding with a rapid onset of methanogenic conditions. However, there was a quick wash, reducing concentrations to below one third of the initial values before the first year. pH values influenced concentrations of some pollutants such as copper. These results indicate that, right from the beginning of disposal, such facilities should be prepared to treat a high pollution load in the leachate and install the gas emissions control elements due to the rapid onset of methanogenesis.This work is funded by the Spanish Ministry of Economics and Competitiveness through the CTM2012-35055 project. The project is financed jointly by the European Regional Development Fund, FEDER (operational period 2007-2013). The authors wish to thank the Government of Cantabria, through the public company MARE, and TirCantabria, the landfill operator company, for their collaboration

    Quantization of pure gravitational plane waves

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    Pure gravitational plane waves are considered as a special case of spacetimes with two commuting spacelike Killing vector fields. Starting with a midisuperspace that describes this kind of spacetimes, we introduce gauge-fixing and symmetry conditions that remove all non-physical degrees of freedom and ensure that the classical solutions are plane waves. In this way, we arrive at a reduced model with no constraints and whose only degrees of freedom are given by two fields. In a suitable coordinate system, the reduced Hamiltonian that generates the time evolution of this model turns out to vanish, so that all relevant information is contained in the symplectic structure. We calculate this symplectic structure and particularize our discussion to the case of linearly polarized plane waves. The reduced phase space can then be described by an infinite set of annihilation and creation like variables. We finally quantize the linearly polarized model by introducing a Fock representation for these variables.Comment: 11 pages, Revtex, no figure

    Measurement of the cross-section and charge asymmetry of WW bosons produced in proton-proton collisions at s=8\sqrt{s}=8 TeV with the ATLAS detector

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    This paper presents measurements of the W+μ+νW^+ \rightarrow \mu^+\nu and WμνW^- \rightarrow \mu^-\nu cross-sections and the associated charge asymmetry as a function of the absolute pseudorapidity of the decay muon. The data were collected in proton--proton collisions at a centre-of-mass energy of 8 TeV with the ATLAS experiment at the LHC and correspond to a total integrated luminosity of 20.2~\mbox{fb^{-1}}. The precision of the cross-section measurements varies between 0.8% to 1.5% as a function of the pseudorapidity, excluding the 1.9% uncertainty on the integrated luminosity. The charge asymmetry is measured with an uncertainty between 0.002 and 0.003. The results are compared with predictions based on next-to-next-to-leading-order calculations with various parton distribution functions and have the sensitivity to discriminate between them.Comment: 38 pages in total, author list starting page 22, 5 figures, 4 tables, submitted to EPJC. All figures including auxiliary figures are available at https://atlas.web.cern.ch/Atlas/GROUPS/PHYSICS/PAPERS/STDM-2017-13
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