28 research outputs found

    Einstein-like geometric structures on surfaces

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    An AH (affine hypersurface) structure is a pair comprising a projective equivalence class of torsion-free connections and a conformal structure satisfying a compatibility condition which is automatic in two dimensions. They generalize Weyl structures, and a pair of AH structures is induced on a co-oriented non-degenerate immersed hypersurface in flat affine space. The author has defined for AH structures Einstein equations, which specialize on the one hand to the usual Einstein Weyl equations and, on the other hand, to the equations for affine hyperspheres. Here these equations are solved for Riemannian signature AH structures on compact orientable surfaces, the deformation spaces of solutions are described, and some aspects of the geometry of these structures are related. Every such structure is either Einstein Weyl (in the sense defined for surfaces by Calderbank) or is determined by a pair comprising a conformal structure and a cubic holomorphic differential, and so by a convex flat real projective structure. In the latter case it can be identified with a solution of the Abelian vortex equations on an appropriate power of the canonical bundle. On the cone over a surface of genus at least two carrying an Einstein AH structure there are Monge-Amp`ere metrics of Lorentzian and Riemannian signature and a Riemannian Einstein K"ahler affine metric. A mean curvature zero spacelike immersed Lagrangian submanifold of a para-K"ahler four-manifold with constant para-holomorphic sectional curvature inherits an Einstein AH structure, and this is used to deduce some restrictions on such immersions

    Experiencia en la ETS de Ingeniería y Diseño Industrial en la implantación del Doble Grado en Ingeniería en Diseño Industrial y Desarrollo de Producto y en Ingeniería Mecánica por la Universidad Politécnica de Madrid

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    (SPA) En este trabajo se plantea el desarrollo curricular del Doble Grado en Ingeniería en Diseño Industrial y Desarrollo de Producto y en Ingeniería Mecánica. Se exponen los motivos por los que se decidió implantar, se ofrecen datos de demanda, oferta, notas de corte y se presenta un avance de los resultados académicos del primer curso correspondiente a la primera promoción. (ENG) In this work the study plan of the doble degree in Industrial Desing an Product development and in Mechanical Engineering. The reasons why the double dergree was implanted, the demand, the offer and the students academic results of the first class

    Claves de éxito para la implantación de un proceso de mentoría en una Escuela Técnica Superior de Ingeniería

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    (SPA) El trabajo que se presenta en esta comunicación tiene el objetivo de resaltar algunas de las claves de éxito para la implantación de un proceso de mentoría en una Escuela Técnica en base a la experiencia desarrollada por profesores que participan como tutores en un Proyecto de Mentoría. El trabajo se desarrolla en un formato de pregunta ? respuesta para facilitar la comprensión y permitir replicar la ejecución de un proceso de características similares. (ENG) This communication describes the keys for the successful implantation of a mentoring process in an engineering school based on the experience of the professors who have participated as mentors in the mentoring program Proyecto Mentor. The exposition has a question-response format to facilitate the understanding necessary to replicate in practice a program with similar characteristics

    Search for dark matter produced in association with bottom or top quarks in √s = 13 TeV pp collisions with the ATLAS detector

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    A search for weakly interacting massive particle dark matter produced in association with bottom or top quarks is presented. Final states containing third-generation quarks and miss- ing transverse momentum are considered. The analysis uses 36.1 fb−1 of proton–proton collision data recorded by the ATLAS experiment at √s = 13 TeV in 2015 and 2016. No significant excess of events above the estimated backgrounds is observed. The results are in- terpreted in the framework of simplified models of spin-0 dark-matter mediators. For colour- neutral spin-0 mediators produced in association with top quarks and decaying into a pair of dark-matter particles, mediator masses below 50 GeV are excluded assuming a dark-matter candidate mass of 1 GeV and unitary couplings. For scalar and pseudoscalar mediators produced in association with bottom quarks, the search sets limits on the production cross- section of 300 times the predicted rate for mediators with masses between 10 and 50 GeV and assuming a dark-matter mass of 1 GeV and unitary coupling. Constraints on colour- charged scalar simplified models are also presented. Assuming a dark-matter particle mass of 35 GeV, mediator particles with mass below 1.1 TeV are excluded for couplings yielding a dark-matter relic density consistent with measurements

    The Science Performance of JWST as Characterized in Commissioning

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    This paper characterizes the actual science performance of the James Webb Space Telescope (JWST), as determined from the six month commissioning period. We summarize the performance of the spacecraft, telescope, science instruments, and ground system, with an emphasis on differences from pre-launch expectations. Commissioning has made clear that JWST is fully capable of achieving the discoveries for which it was built. Moreover, almost across the board, the science performance of JWST is better than expected; in most cases, JWST will go deeper faster than expected. The telescope and instrument suite have demonstrated the sensitivity, stability, image quality, and spectral range that are necessary to transform our understanding of the cosmos through observations spanning from near-earth asteroids to the most distant galaxies.Comment: 5th version as accepted to PASP; 31 pages, 18 figures; https://iopscience.iop.org/article/10.1088/1538-3873/acb29

    The James Webb Space Telescope Mission

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    Twenty-six years ago a small committee report, building on earlier studies, expounded a compelling and poetic vision for the future of astronomy, calling for an infrared-optimized space telescope with an aperture of at least 4m4m. With the support of their governments in the US, Europe, and Canada, 20,000 people realized that vision as the 6.5m6.5m James Webb Space Telescope. A generation of astronomers will celebrate their accomplishments for the life of the mission, potentially as long as 20 years, and beyond. This report and the scientific discoveries that follow are extended thank-you notes to the 20,000 team members. The telescope is working perfectly, with much better image quality than expected. In this and accompanying papers, we give a brief history, describe the observatory, outline its objectives and current observing program, and discuss the inventions and people who made it possible. We cite detailed reports on the design and the measured performance on orbit.Comment: Accepted by PASP for the special issue on The James Webb Space Telescope Overview, 29 pages, 4 figure

    Visions of Globalization: Inequality and Political Stability

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    Combined Forward-Backward Asymmetry Measurements in Top-Antitop Quark Production at the Tevatron

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    Combined Forward-Backward Asymmetry Measurements in Top-Antitop Quark Production at the Tevatron

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