277 research outputs found

    A sequence of polynomials with optimal condition number

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    We find an explicit sequence of univariate polynomials of arbitrary degree with optimal condition number. This solves a problem posed by Michael Shub and Stephen Smale in 1993.The first and second authors were partially supported by Ministerio de Econom´ıa y Competitividad, Gobierno de Espa˜na, through grants MTM2017-83816-P and MTM2017-90682-REDT, and by the Banco de Santander and Universidad de Cantabria grant 21.SI01.64658. The second author was also supported by the Austrian Science Fund FWF project F5503 (part of the Special Research Program (SFB) Quasi-Monte Carlo Methods: Theory and Applications). The third and fourth authors have been partially supported by grant MTM2017-83499-P by the Ministerio de Econom´ıa y Competitividad, Gobierno de Espa˜na and by the Generalitat de Catalunya (project 2017 SGR 358)

    Landau's necessary density conditions for the Hankel transform

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    We will prove an analogue of Landau's necessary conditions [Necessary density conditions for sampling and interpolation of certain entire functions, Acta Math. 117 (1967).] for spaces of functions whose Hankel transform is supported in a measurable subset S of the positive semi-axis. As a special case, necessary density conditions for the existence of Fourier-Bessel frames are obtained.Comment: To appear on J. Funct. Analysi

    Fundación APIP-ACAM. Programa de Igualdad para Trabajadoras Sexuales

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    Este trabajo recoge las memorias de las prácticas realizadas en la Fundación APIP-ACAM dentro del Programa de Igualdad para Trabajadoras Sexuales. Por ello, también incluye un marco teórico acerca del fenómeno de la prostitución y de la trata de seres humanos con fines de explotación sexual, información de la entidad y una serie de propuestas de mejora

    Self-consistent treatment of thermal effects in neutron-star post-mergers: observational implications for third-generation gravitational-wave detectors

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    We assess the impact of accurate, self-consistent modelling of thermal effects in neutron-star merger remnants in the context of third-generation gravitational-wave detectors. This is done through the usage, in Bayesian model selection experiments, of numerical-relativity simulations of binary neutron star (BNS) mergers modelled through: a) nuclear, finite-temperature (or ``tabulated'') equations of state (EoSs), and b) their simplifed piecewise (or ``hybrid'') representation. These cover four different EoSs, namely SLy4, DD2, HShen and LS220. Our analyses make direct use of the Newman-Penrose scalar ψ4\psi_4 outputted by numerical simulations. Considering a detector network formed by three Cosmic Explorers, we show that differences in the gravitational-wave emission predicted by the two models are detectable with a natural logarithmic Bayes Factor logB5\log{\cal{B}}\geq 5 at average distances of dL50d_L \simeq 50Mpc, reaching dL100d_L \simeq 100Mpc for source inclinations ι0.8\iota \leq 0.8, regardless of the EoS. This impact is most pronounced for the HShen EoS. For low inclinations, only the DD2 EoS prevents the detectability of such modelling differences at dL150d_L \simeq 150Mpc. Our results suggest that the usage a self-consistent treatment of thermal effects is crucial for third-generation gravitational wave detectors.Comment: 9 pages, 3 Figure

    Tuning the Graphene on Ir(111) adsorption regime by Fe/Ir surface-alloying

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    A combined scanning tunneling microscopy, x-ray photoelectron spectroscopy, angle-resolved photoemission spectroscopy, and density functional theory study of graphene on a Fe-Ir(111) alloy with variable Ir concentration is presented. Starting from an intercalated Fe layer between the graphene and Ir(111) surface we find that graphene-substrate interaction can be fine-tuned by Fe-Ir alloying at the interface. When a critical Ir-concentration close to 0.25 is reached in the Fe layer, the Dirac cone of graphene is largely restored and can thereafter be tuned across the Fermi level by further increasing the Ir content. Indeed, our study reveals an abrupt transition between a chemisorbed phase at small Ir concentrations and a physisorbed phase above the critical concentration. The latter phase is highly reminiscent of the graphene on the clean Ir(111) surface. Furthermore, the transition is accompanied by an inversion of the graphene''s induced magnetization due to the coupling with the Fe atoms from antiferromagnetic when chemisorbed to weakly ferromagnetic in the physisorption regime, with spin polarizations whose magnitude may be tuned with the amount of Fe content

    Recursos sociales para mujeres que ejercen la prostitución heterosexual en la ciudad de Zaragoza

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    Estudio de los diferentes recursos sociales de la ciudad de Zaragoza que trabajan directamente con las mujeres que ejercen la prostitución, para conocer qué servicios ofrece cada uno de ellos, determinar cuál es el perfil de las mujeres que atienden y establecer propuestas de mejora de la intervención con las mismas

    Guiding signs in metabolic disease diagnosis

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    Los errores innatos del metabolismo son un grupo de enfermedades genéticas con sintomatología muy inespecífica y por tanto difícil diagnóstico si no existe una sospecha clínica elevada. Sin embargo existen algunos datos de la exploración física y de las pruebas complementarias que pueden enfocar el proceso diagnóstico hacia la solicitud de pruebas específicas que lo confirmen. El caso que presentamos trata de destacar algunos de estos datos que pueden hacer sospechar la existencia de un defecto congénito de la glucosilación de proteínas, trastorno infrecuente pero con algunas formas tratables, por lo que su sospecha y diagnóstico precoz es de vital importanciaInborn errors of metabolism are a group of genetic diseases with non specific symptoms and therefore difficult to diagnose without high clinical suspicion. However there are some physical examination data and laboratory tests that can focus the diagnostic process to the implementation of specific tests to confirm them. The case exposed highlights some of these data that can make us suspect the existence of a congenital defect of glycosylation of proteins, rare disorder but with some treatable variations, that make their suspicion and early diagnosis of great importanc
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