468 research outputs found

    N=2 SUGRA BPS Multi-center solutions, quadratic prepotentials and Freudenthal transformations

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    We present a detailed description of N=2 stationary BPS multicenter black hole solutions for quadratic prepotentials with an arbitrary number of centers and scalar fields making a systematic use of the algebraic properties of the matrix of second derivatives of the prepotential, S\mathcal{S}, which in this case is a scalar-independent matrix. In particular we obtain bounds on the physical parameter of the multicenter solution such as horizon areas and ADM mass. We discuss the possibility and convenience of setting up a basis of the symplectic vector space built from charge eigenvectors of the \ssigma, the set of vectors (\Ppm q_a) with \Ppm \ssigma-eigenspace proyectors. The anti-involution matrix S\mathcal{S} can be understood as a Freudenthal duality \tilde{x}=\ssigma x. We show that this duality can be generalized to "Freudenthal transformations" x\to \lambda\exp(\theta \ssigma) x= a x+b\tilde{x} under which the horizon area, ADM mass and intercenter distances scale up leaving constant the fix point scalars. In the special case λ=1\lambda=1, "\ssigma-rotations", the transformations leave invariant the solution. The standard Freudental duality can be written as \tilde x= \exp(\pi/2 \ssigma) x . We argue that these generalized transformations leave also invariant the general stringy extremal quartic form Δ4\Delta_4, Δ4(x)=Δ4(cosθx+sinθx~)\Delta_4(x)= \Delta_4(\cos\theta x+\sin\theta\tilde{x}).Comment: Latex 27 pages (11pt). Some modifications introduced. Minor misprints corrected. References adde

    N=2 SUGRA BPS multi-center black holes and freudenthal triple systems

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    We present a detailed description of N = 2 stationary BPS multicenter black hole solutions for quadratic prepotentials with an arbitrary number of centers and scalar fields making a systematic use of the algebraic properties of the matrix of second derivatives of the prepotential, S, which in this case is a scalar-independent matrix. The anti-involution matrix S can be understood as a Freudenthal duality x̃ = Sx. We show that this duality can be generalized to “Freudenthal transformations”

    Entanglement renormalization for interacting field theories

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    A general method to build the entanglement renormalization (cMERA) for interacting quantum field theories is presented. We improve upon the well-known Gaussian formalism used in free theories through a class of variational non-Gaussian wave functionals for which expectation values of local operators can be efficiently calculated analytically and in a closed form. The method consists of a series of scale-dependent nonlinear canonical transformations on the fields of the theory under consideration. Here, the lambda phi(4) and the sine-Gordon scalar theories are used to illustrate how nonperturbative effects far beyond the Gaussian approximation are obtained by considering the energy functional and the correlation functions of the theory.J.J.F.M. acknowledges A. Bhattacharyya and T. Takayanagi for useful discussions and comments. J.M.V. thanks J. Cotler and M. Muller for many fruitful discussions. The work of J.J.F. M. is supported by Universidad de Murcia. J.M.V. is supported by Ministerio de Economia y Competitividad FIS2015-69512-R and Programa de Excelencia de la Fundacion Seneca 19882/GERM/15. J.J.F. M. and E.T.L. acknowledge the financial support of Spanish Ministerio de Economia y Competitividad and CARM Fundacion Seneca under Grants No. FIS2015-28521 and No. 21257/PI/19

    Liderar para Innovar. Innovar para Crear

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    Nos proponemos que a partir de nuestra práctica reflexiva situada, aquellos partícipes de la jornada puedan vivenciar las etapas atravesadas en el desarrollo y la aplicación del Marco de Enseñanza para la Comprensión en todos los espacios curriculares del Nivel Secundario de nuestro colegio, a partir de la ruptura con los paradigmas tradicionales de la gestión de la enseñanza en el aula. Se enunciarán los modos de hacer, desde el asesoramiento y la supervisión del equipo de conducción. Se presentará una unidad didáctica planificada desde el Marco de EPC y evidencias que avalan la mejora significativa en dicha práctica áulica. Se ha encontrado esta experiencia en el espacio curricular de Política y Ciudadanía de 5° año de Educación Secundaria. El tópico generativo presentado para abordar su comprensión ha sido ¿Qué significa e implica pensar el Poder

    Using Cartesian Coordinate Systems to Create, Classify, and Retrieve Biomedical Time-Series: Applications to 24-hour Ambulatory Blood Pressure Monitoring

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    Background: Ambulatory Blood Pressure Measurement (ABPM) allows physicians to monitor blood pressure variability under everyday living conditions and predicts clinical outcomes better than conventional blood-pressure measurement. ABPM can demonstrate mean arterial pressure (MAP) behavior over 24 hours relevant to clinical practice, such as nocturnal hypertension or increased blood pressure variability. We hypothesized that individuals with the same cardiovascular health status would have the same MAP signal (MAPs) waveform. Methods: This study reutilizes a data subset from the IDACO Consortium to create 24-hour MAPs. We assigned all the MAPs to data matrix X, performed principal components analysis (PCA) to X, and calculated the percentage of the total variance explained by each of the 82 principal components (PC). The first three PC explained 85.03%, 9.47%, and 5.50% of the total variance. We used every MAP signal\u27s first three PC scores as their three-dimensional Euclidean Space (x, y, z) coordinates and assigned them to matrix C. Then, we calculated hierarchical clusters of the rows of C with Ward\u27s linkage minimum variance algorithm and a Euclidian metric and encoded this information on the agglomerative hierarchical cluster tree Z. We determined the gap statistic in Z to obtain the optimal number of clusters. We created seven agglomerative clusters from the linkages stored in Z, using Ward’s distance as the criterion for defining the clusters. Finally, we plotted and colored the mapped MAPs by their assigned cluster number at the locations specified by their (x, y, z) coordinates. Results: The MAPs cartesian representations show that MAPs with similar waveforms cluster in the same three-dimensional Euclidean subspace. These patterns identified individuals with dipping and non-dipping blood pressure behavior, which is relevant to clinical management. Conclusions: Mapping a set of physiological signals into a Euclidian space creates a mathematical formalism that provides a statistical framework to classify physiological signals by their waveform. By applying our method to existing electrophysiological and physiological databases, we can cluster any biomedical time-series (blood pressure, ECG, EEG, EMG, patch-clamp, single-unit recordings, etc.) by physiologic or pathological waveform, so further epidemiological and genetic studies can be conducted on the subjects or tissue samples sharing similar patterns

    24-Hour Blood Pressure Variability Assessed by Average Real Variability: A Systematic Review and Meta-Analysis

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    Background-—Although 24-hour blood pressure (BP) variability (BPV) is predictive of cardiovascular outcomes independent of absolute BP levels, it is not regularly assessed in clinical practice. One possible limitation to routine BPV assessment is the lack of standardized methods for accurately estimating 24-hour BPV. We conducted a systematic review to assess the predictive power of reported BPV indexes to address appropriate quantification of 24-hour BPV, including the average real variability (ARV) index. Methods and Results-—Studies chosen for review were those that presented data for 24-hour BPV in adults from meta-analysis, longitudinal or cross-sectional design, and examined BPV in terms of the following issues: (1) methods used to calculate and evaluate ARV; (2) assessment of 24-hour BPV determined using noninvasive ambulatory BP monitoring; (3) multivariate analysis adjusted for covariates, including some measure of BP; (4) association of 24-hour BPV with subclinical organ damage; and (5) the predictive value of 24-hour BPV on target organ damage and rate of cardiovascular events. Of the 19 assessed studies, 17 reported significant associations between high ARV and the presence and progression of subclinical organ damage, as well as the incidence of hard end points, such as cardiovascular events. In all these cases, ARV remained a significant independent predictor (P Conclusions-—Current evidence suggests that ARV index adds significant prognostic information to 24-hour ambulatory BP monitoring and is a useful approach for studying the clinical value of BPV

    Performance of a cryogenic system prototype for the XENON1T Detector

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    We have developed an efficient cryogenic system with heat exchange and associated gas purification system, as a prototype for the XENON1T experiment. The XENON1T detector will use about 3 ton of liquid xenon (LXe) at a temperature of 175K as target and detection medium for a dark matter search. In this paper we report results on the cryogenic system performance focusing on the dynamics of the gas circulation-purification through a heated getter, at flow rates above 50 Standard Liter per Minute (SLPM). A maximum flow of 114 SLPM has been achieved, and using two heat exchangers in parallel, a heat exchange efficiency better than 96% has been measured
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