5,511 research outputs found

    Charged rotating black holes in higher dimensions

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    We use a recent implementation of the large DD expansion in order to construct the higher-dimensional Kerr-Newman black hole and also new charged rotating black bar solutions of the Einstein-Maxwell theory, all with rotation along a single plane. We describe the space of solutions, obtain their quasinormal modes, and study the appearance of instabilities as the horizons spread along the plane of rotation. Generically, the presence of charge makes the solutions less stable. Instabilities can appear even when the angular momentum of the black hole is small, as long as the charge is sufficiently large. We expect that, although our study is performed in the limit D→∞D\to\infty, the results provide a good approximation for charged rotating black holes at finite D≥6D\geq 6.Comment: 21 pages, 1 figur

    Critical exponents for the long-range Ising chain using a transfer matrix approach

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    The critical behavior of the Ising chain with long-range ferromagnetic interactions decaying with distance rαr^\alpha, 1<α<21<\alpha<2, is investigated using a numerically efficient transfer matrix (TM) method. Finite size approximations to the infinite chain are considered, in which both the number of spins and the number of interaction constants can be independently increased. Systems with interactions between spins up to 18 sites apart and up to 2500 spins in the chain are considered. We obtain data for the critical exponents ν\nu associated with the correlation length based on the Finite Range Scaling (FRS) hypothesis. FRS expressions require the evaluation of derivatives of the thermodynamical properties, which are obtained with the help of analytical recurrence expressions obtained within the TM framework. The Van den Broeck extrapolation procedure is applied in order to estimate the convergence of the exponents. The TM procedure reduces the dimension of the matrices and circumvents several numerical matrix operations.Comment: 10 pages, 2 figures, Conference NEXT Sigma Ph

    Electoral Libels: A Comparative Study of the English and Ecuadorian Law of Defamation

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    English and Ecuadorian defamation law have developed very different mechanisms to resolve the tension between the right to freedom of speech and the protection of private life. Ordinarily this would not be too surprising, insofar as it is natural that different countries will have different legal institutions. However, this divergence becomes relevant because both jurisdictions claim to be bound by virtually the same human rights obligations when it comes to speech related to matters of public interest. For this reason, this article focuses on speech issued during electoral campaigns—perhaps the best example of public interest speech—in order to assess how different jurisdictions prioritise between the different rights and interests at play in these kind of defamation cases

    Analytical approach to directed sandpile models on the Apollonian network

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    We investigate a set of directed sandpile models on the Apollonian network, which are inspired on the work by Dhar and Ramaswamy (PRL \textbf{63}, 1659 (1989)) for Euclidian lattices. They are characterized by a single parameter qq, that restricts the number of neighbors receiving grains from a toppling node. Due to the geometry of the network, two and three point correlation functions are amenable to exact treatment, leading to analytical results for the avalanche distributions in the limit of an infinite system, for q=1,2q=1,2. The exact recurrence expressions for the correlation functions are numerically iterated to obtain results for finite size systems, when larger values of qq are considered. Finally, a detailed description of the local flux properties is provided by a multifractal scaling analysis.Comment: 7 pages in two-column format, 10 illustrations, 5 figure

    El comentario de Santayana y Spinosa: (1568) al Tratado de la esfera de Sacrobosco

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    Durante el siglo XVI se hicieron en España varios comentarios y traducciones al Tratado de la esfera de Johannes de Sacrobosco (Martins, 2004). Hubo una única edición en latín, comentada, de Pedro de Espinosa (1550) y se publicaron diversas traducciones parciales o, comentadas. Las del último tipo son tres: de Jerónimo de Chaves (1545), de Rodrigo Saenz de Santayana y Spinosa (1568) y de Ginés de Rocarnora y Torrano (1599). El objetivo de este trabajo es analizar especialmente una de estas -la que fue publicada en el 1568 por Santayana y Spinosa - discutiendo sus peculiaridades y presentando una breve comparación con las otras dos versiones castellanas de los quinientos
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