3,733 research outputs found

    Forward-Backward and Charge Asymmetries in the Standard Model

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    This talk reviews the Standard Model predictions for the top-quark forward backward and charge asymmetries measured at the Tevatron and at the LHC.Comment: 8 pages, 2 figures. Proceedings of CKM 2012, the 7th International Workshop on the CKM Unitarity Triangle, University of Cincinnati, USA, 28 September - 2 October 201

    Numerical Loop-Tree Duality: contour deformation and subtraction

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    We introduce a novel construction of a contour deformation within the framework of Loop-Tree Duality for the numerical computation of loop integrals featuring threshold singularities in momentum space. The functional form of our contour deformation automatically satisfies all constraints without the need for fine-tuning. We demonstrate that our construction is systematic and efficient by applying it to more than 100 examples of finite scalar integrals featuring up to six loops. We also showcase a first step towards handling non-integrable singularities by applying our work to one-loop infrared divergent scalar integrals and to the one-loop amplitude for the ordered production of two and three photons. This requires the combination of our contour deformation with local counterterms that regulate soft, collinear and ultraviolet divergences. This work is an important step towards computing higher-order corrections to relevant scattering cross-sections in a fully numerical fashion.Comment: 87 page

    MayDay: VestAndPage Workshop Concept, Theory and Practice

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    Considerations on how VestAndPage facilitate a workshop on Performance art. Text published in: "How We Teach Performance Art: University Courses and Workshop Syllabus", Edited by Valentin Torrens. Outskirts Press, July 2014. The book offers 42 different approaches to transmit the generative source of creativity in live action by internationally experienced practitioners, teachers and theorists of performance art from 21 countries. 340 pages full of ideas, points of view, methodologies, sensitivities, exercises and proposals to enjoy live practice with deeper involvement immersion, knowledge and study. The book begins with a clarification of the terms used to name this practice and continues with the cultural introductions previously to the appearance of the performance as an artistic differentiated activity. To see the performance's creative nature and its relation with the game; its communicative qualities and his perception. It's followed by a report on previous books and publications related to the pedagogies of the performance. Later, a description of education affiliations, inside the pedagogic common tendencies of performance courses. An approach to courses and workshop's characteristics. It's begun with the syllabus and the comments of the university courses and continues with the workshops. Some teachers have sent a text on their relation to the performance; in those cases, it's placed before the description of the syllabus, in order to complement, from the subjective intimacy, our best comprehension of his work and his course. After the entire syllabus, there is a small biographical summary of the authors and bibliography on performance

    DISTRIBUTION OF PIGMENT CELLS IN THE HEART OF THE RABBITFISH, CHIMAERA MONSTROSA (CONDRICHTHYES: HOLOCEPHALI)

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    El resumen aparece en el Program & Abstracts of the 10th International Congress of Vertebrate Morphology, Barcelona 2013. Anatomical Record, Volume 296, Special Feature — 1: P-076.The study of extracutaneous cells producing and storing melanin is of interest because it may provide valuable information about the presence of neural crest elements in internal organs and tissues. Here we report, for the first time, the presence and distribution of melanophores in the heart of a chondrichthyan species, the rabbitfish, Chimaera monstrosa. Pigment cells were found in all of 20 hearts examined. Pigment cells occur mainly in the cardiac outflow tract, which consists of two anatomical components, the proximal, myocardial conus arteriosus and the distal, non-myocardial bulbus arteriosus. A few groups of dark pigmented cells were found in the apex of the ventricle of one specimen and in the atrium of two specimens. In all instances, the melanophores were located in the subepicardial space, where they could be well recognized in both unstained and stained histological sections. The distribution and intensity of the pigmentation in the cardiac outflow tract varies markedly between individuals. In all cases, however, the pigmented area is larger on the dorsal than on the ventral surface. Dorsally, the size of the pigmented area ranges from a fringe that includes the bulbus and the distal part of the conus to the whole surface of the outflow tract. Ventrally, the pigmented area does not cover the entire conus arteriosus. The intensity of the pigmentation also varies widely; in general, it is highest at the distal portion of the conus. There is no relationship between the distribution and intensity of the pigmentation and the sex and age of the animals. The functional role of the pigmented cells is unknown. If the melanophores in the heart of C. monstrosa are indeed of neural crest origin, it would suggest a notable contribution of the neural crest cells to the cardiac outflow tract in holocephalans.Proyecto CGL2010-16417/BOS; Fondos FEDER BES-2011-04690

    The bulbus arteriosus of the holocephalan heart

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    El resumen aparece en el Program & Abstracts of the 10th International Congress of Vertebrate Morphology, Barcelona 2013.Anatomical Record, Volume 296, Special Feature — 1: P-074.Previous work has shown that the outflow tract of the elasmobranch heart, namely the cardiac portion intercalated between the ventricle and the ventral aorta, does not consist of a single component, the conus arteriosus, as has classically been assumed, but two, the myocardial conus arteriosus and the non-myocardial bulbus arteriosus. From the evolutionary perspective, knowledge of the anatomy of the cardiac outflow tract of the holocephali is important, as they are the sister group of elasmobranchs. Our aim is to describe the cardiac outflow tract of four holocephalan species, two of them, Chimaera monstrosa and Hydrolagus affinis of the family Chimaeridae, and the other two, Harriotta raleighana and Rhinochimaera atlantica, of the family Rhinochimaeridae. The cardiac outflow tract of the four species consisted of a myocardial conus arteriosus, furnished with valves, and a bulbus arteriosus devoid of cardiac muscle. Both the bulbus and conus are tubular in shape. The length of the bulbus relative to the total length of the outflow tract is somewhat smaller in the rhinochimaerids (15%-19%) than in the chimaerids (19%-23%). The bulbus is covered by epicardium and is crossed by the main coronary artery trunks. Histologically, the bulbus is mainly composed of elastin and collagen, and, to a lesser extent, by smooth muscle. This suggests that in holocephalans, the bulbus actively helps to protect the gill vasculature from exposure to high-pressure pulses of blood. Our results prove that the bulbus arteriosus is common to chondrichthyans. In addition, they support the hypothesis that the cardiac outflow tract consisted of a conus arteriosus and a bulbus arteriosus from the beginning of the jawed vertebrate radiation, contributing to our understanding of the morphological changes that have occurred at the arterial pole of the heart in both actinopterygians and sarcopterygians.Proyecto CGL2010-16417/BOS; Fondos FEDE

    Local Unitarity: a representation of differential cross-sections that is locally free of infrared singularities at any order

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    We propose a novel representation of differential scattering cross-sections that locally realises the direct cancellation of infrared singularities exhibited by its so-called real-emission and virtual degrees of freedom. We take advantage of the Loop-Tree Duality representation of each individual forward-scattering diagram and we prove that the ensuing expression is locally free of infrared divergences, applies at any perturbative order and for any process without initial-state collinear singularities. Divergences for loop momenta with large magnitudes are regulated using local ultraviolet counterterms that reproduce the usual Lagrangian renormalisation procedure of quantum field theories. Our representation is especially suited for a numerical implementation and we demonstrate its practical potential by computing fully numerically and without any IR counterterm the next-to-leading order accurate differential cross-section for the process e+e−→ddˉe^+ e^- \rightarrow d \bar{d}. We also show first results beyond next-to-leading order by computing interference terms part of the N4LO-accurate inclusive cross-section of a 1→2+X1\rightarrow 2+X scalar scattering process.Comment: 88 page

    Prevalence of Dog Erythrocyte Antigen 1 in 7, 414 Dogs in Italy

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    The study aim was to establish the prevalence of DEA 1, the most immunogenic and clinically important blood group in canine blood transfusion, in 7,414 dogs from Italy. The potential sensitization risk following a first transfusion and the acute reaction risk following a second transfusion given without a cross-matching and blood typing test were also calculated. Dogs tested were purebred (4,798) and mongrel (2,616); 38.8% were DEA 1 negative and 61.2% were DEA 1 positive. High prevalence for DEA 1 positive blood type was found in Ariegeois and English Setter, whereas German Shepherd and Boxer had higher DEA 1 negative blood type. Breeds with blood type never reported before included French Brittany Spaniel and Pug showing a high prevalence of DEA 1 positive type, while French Bulldog and West Highland White Terrier were more often DEA 1 negative. Just 48.8% of purebred and 13.9% of mongrel dogs were considered as prospective blood donors based upon their blood type.Most of the breeds had a sensitization risk of 20.0–25.0%. Rottweiler and Ariegeois had less risk of sensitization (9.4 and 4.2%) and the minor risk of an acute transfusional reaction (0.9–0.2%).The prevalence of DEA 1 positive and negative dogs in Italy agrees withmost of the data already reported in the literature

    Optimal Variance Control of the Score Function Gradient Estimator for Importance Weighted Bounds

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    This paper introduces novel results for the score function gradient estimator of the importance weighted variational bound (IWAE). We prove that in the limit of large KK (number of importance samples) one can choose the control variate such that the Signal-to-Noise ratio (SNR) of the estimator grows as K\sqrt{K}. This is in contrast to the standard pathwise gradient estimator where the SNR decreases as 1/K1/\sqrt{K}. Based on our theoretical findings we develop a novel control variate that extends on VIMCO. Empirically, for the training of both continuous and discrete generative models, the proposed method yields superior variance reduction, resulting in an SNR for IWAE that increases with KK without relying on the reparameterization trick. The novel estimator is competitive with state-of-the-art reparameterization-free gradient estimators such as Reweighted Wake-Sleep (RWS) and the thermodynamic variational objective (TVO) when training generative models

    A reduced-order model for segregated fluid-structure interaction solvers based on an ALE approach

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    This article presents a Galerkin projection model order reduction approach for fluid-structure interaction (FSI) problems in the Finite Volume context. The reduced-order model (ROM) is based on proper orthogonal decomposition (POD), where a reduced basis is formed using energy-dominant POD modes. The reduced basis also consists of characteristics of the POD time modes derived from the POD time modes coefficients. In addition, the solution state vector comprises the mesh deformation, considering the structural motion in FSI. The results are obtained by applying the proposed method to time-dependent problems governed by the 2D incompressible Navier-Stokes equations. The main objective of this work is to introduce a hybrid technique mixing up the classical Galerkin-projection approach with a data-driven method to obtain a versatile and accurate algorithm for resolving FSI problems with moving meshes. The effectiveness of this approach is demonstrated in the case study of vortex-induced vibrations (VIV) of a cylinder at Reynolds number Re = 200. The results show the stability and accuracy of the proposed method with respect to the high-dimensional model by capturing transient flow fields and, more importantly, the forces acting on the moving objects
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