3,172 research outputs found

    Carbon-supported shape-controlled Pt nanoparticle electrocatalysts for direct alcohol fuel cells

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    The demand for power sources alternative to fossil fuels makes urgent the development of more efficient electrocatalysts for fuel cells applications and the maximization of the performances of the existent ones. This work reports, for the first time, the use of carbon-supported shape-controlled Pt nanoparticles as anode catalysts in direct ethanol fuel cells. By using cubic Pt nanoparticles, on which (100) surface sites are predominant, the performance of the fuel cell can be increased from 14 to 24 mW per mg of Pt when compared with cuboctahedral nanoparticles. Moreover, the open circuit potential shifts about 50 mV toward more positive potentials. In comparison with commercially available Pt catalysts, the performance for the (100) preferentially oriented nanoparticles is about three times higher. The reported results evidence that, from an applied point of view, the effect of the surface structure/shape of the electrocatalysts can be also considered to improve the performance of real fuel cell systems.The financial support from Aalto University is acknowledged

    Aplicación del modelo alternativo de diagnóstico de Trastorno de la Personalidad DSM-5 para valorar la evolución de una paciente adolescente: caso clínico

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    La quinta edición del Manual Diagnóstico y Estadístico de Trastornos Mentales, en su Sección III, presenta un modelo alternativo para el diagnóstico de los Trastornos de la Personalidad que intenta eliminar algunos de los problemas que aparecen con el modelo oficial presentado en la sección II del manual. Es de considerable interés la posibilidad que ofrece este modelo, cuyos ejes son el funcionamiento de la personalidad y los rasgos de la personalidad, de poder caracterizar con precisión a un paciente que cumple criterios de varios trastornos de la personalidad o no cumple criterios de uno concreto. También se contempla la posibilidad de utilizarlo como herramienta para la valoración de la funcionalidad de un paciente y el diseño de un plan terapéutico en función de su personalidad. En este artículo se presenta a una paciente con alteraciones del comportamiento, se caracteriza su personalidad según este modelo y se observa su evolución.The Diagnostic and Statistical Manual of Mental Disorders, fifth edition, presents in its Section III an alternative model for diagnosing Personality Disorders, which tries to amend some of the problems of the official model, included in Section II. Is it of remarkable interest the possibility that this model, whose main axes are the personality functioning and the personality traits, brings us of being able to characterize with precision a patient that meets criteria of more than one personality disorders or does not fully meet criteria for a single one. The possibility of using it as a tool to evaluate the functioning of a patient and designing a specific treatment plan according to his or her personality is also contemplated. In this article is present a patient whose behaviour is altered, her personality is characterised according to this model and he evolution is observed

    Analytic approximations for the broadening of the spectral lines of hydrogen-like ions

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    Broadband approximate expressions for calculating the broadening of the spectral lines of hydrogenlike ions in a multicomponent plasma are derived taking into account both the influence of the interaction between plasma particles on the distribution function of the plasma microfield and the effect of the microfield dynamics on the broadening of the central component of the spectral line. With the approximate expressions proposed, the calculation of the shape of a given spectral line of a certain ion in a plasma with a given ion composition requires only a few seconds of computer time. The approximate expressions provide a good computational accuracy not only for the central component of the spectral line but also for the spectral line wings

    Search for the standard model Higgs boson in the H to ZZ to 2l 2nu channel in pp collisions at sqrt(s) = 7 TeV

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    A search for the standard model Higgs boson in the H to ZZ to 2l 2nu decay channel, where l = e or mu, in pp collisions at a center-of-mass energy of 7 TeV is presented. The data were collected at the LHC, with the CMS detector, and correspond to an integrated luminosity of 4.6 inverse femtobarns. No significant excess is observed above the background expectation, and upper limits are set on the Higgs boson production cross section. The presence of the standard model Higgs boson with a mass in the 270-440 GeV range is excluded at 95% confidence level.Comment: Submitted to JHE

    Association of MC1R Variants and host phenotypes with melanoma risk in CDKN2A mutation carriers: a GenoMEL study

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    <p><b>Background</b> Carrying the cyclin-dependent kinase inhibitor 2A (CDKN2A) germline mutations is associated with a high risk for melanoma. Penetrance of CDKN2A mutations is modified by pigmentation characteristics, nevus phenotypes, and some variants of the melanocortin-1 receptor gene (MC1R), which is known to have a role in the pigmentation process. However, investigation of the associations of both MC1R variants and host phenotypes with melanoma risk has been limited.</p> <p><b>Methods</b> We included 815 CDKN2A mutation carriers (473 affected, and 342 unaffected, with melanoma) from 186 families from 15 centers in Europe, North America, and Australia who participated in the Melanoma Genetics Consortium. In this family-based study, we assessed the associations of the four most frequent MC1R variants (V60L, V92M, R151C, and R160W) and the number of variants (1, ≥2 variants), alone or jointly with the host phenotypes (hair color, propensity to sunburn, and number of nevi), with melanoma risk in CDKN2A mutation carriers. These associations were estimated and tested using generalized estimating equations. All statistical tests were two-sided.</p> <p><b>Results</b> Carrying any one of the four most frequent MC1R variants (V60L, V92M, R151C, R160W) in CDKN2A mutation carriers was associated with a statistically significantly increased risk for melanoma across all continents (1.24 × 10−6 ≤ P ≤ .0007). A consistent pattern of increase in melanoma risk was also associated with increase in number of MC1R variants. The risk of melanoma associated with at least two MC1R variants was 2.6-fold higher than the risk associated with only one variant (odds ratio = 5.83 [95% confidence interval = 3.60 to 9.46] vs 2.25 [95% confidence interval = 1.44 to 3.52]; Ptrend = 1.86 × 10−8). The joint analysis of MC1R variants and host phenotypes showed statistically significant associations of melanoma risk, together with MC1R variants (.0001 ≤ P ≤ .04), hair color (.006 ≤ P ≤ .06), and number of nevi (6.9 × 10−6 ≤ P ≤ .02).</p> <p><b>Conclusion</b> Results show that MC1R variants, hair color, and number of nevi were jointly associated with melanoma risk in CDKN2A mutation carriers. This joint association may have important consequences for risk assessments in familial settings.</p&gt

    Search for New Physics with Jets and Missing Transverse Momentum in pp collisions at sqrt(s) = 7 TeV

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    A search for new physics is presented based on an event signature of at least three jets accompanied by large missing transverse momentum, using a data sample corresponding to an integrated luminosity of 36 inverse picobarns collected in proton--proton collisions at sqrt(s)=7 TeV with the CMS detector at the LHC. No excess of events is observed above the expected standard model backgrounds, which are all estimated from the data. Exclusion limits are presented for the constrained minimal supersymmetric extension of the standard model. Cross section limits are also presented using simplified models with new particles decaying to an undetected particle and one or two jets

    Search for anomalous t t-bar production in the highly-boosted all-hadronic final state

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    A search is presented for a massive particle, generically referred to as a Z', decaying into a t t-bar pair. The search focuses on Z' resonances that are sufficiently massive to produce highly Lorentz-boosted top quarks, which yield collimated decay products that are partially or fully merged into single jets. The analysis uses new methods to analyze jet substructure, providing suppression of the non-top multijet backgrounds. The analysis is based on a data sample of proton-proton collisions at a center-of-mass energy of 7 TeV, corresponding to an integrated luminosity of 5 inverse femtobarns. Upper limits in the range of 1 pb are set on the product of the production cross section and branching fraction for a topcolor Z' modeled for several widths, as well as for a Randall--Sundrum Kaluza--Klein gluon. In addition, the results constrain any enhancement in t t-bar production beyond expectations of the standard model for t t-bar invariant masses larger than 1 TeV.Comment: Submitted to the Journal of High Energy Physics; this version includes a minor typo correction that will be submitted as an erratu
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