6,131 research outputs found

    Supersymmetric contributions to B --> K pi in the view of recent experimental result

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    Supersymmetric contributions to the branching ratios and CP asymmetries of B--> K pi decays are analyzed in the view of recent experimental measurements. We show that supersymmetry can still provide a natural solution to the apparent discrepancy between theses results and the standard model expectations. We emphasize that chargino contributions may enhance the electroweak penguin effects that can resolve to the B--> K pi puzzle. We also point out that a non-universal AA-terms is an essential requirement for this solution.Comment: 9 pages, 2 figure

    Developing precision stroke imaging.

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    Stroke experts stand at the cusp of a unique opportunity to advance the care of patients with cerebrovascular disorders across the globe through improved imaging approaches. NIH initiatives including the Stroke Progress Review Group promotion of imaging in stroke research and the newly established NINDS Stroke Trials network converge with the rapidly evolving concept of precision medicine. Precision stroke imaging portends the coming shift to individualized approaches to cerebrovascular disorders where big data may be leveraged to identify and manage stroke risk with specific treatments utilizing an improved neuroimaging infrastructure, data collection, and analysis. We outline key aspects of the stroke imaging field where precision medicine may rapidly transform the care of stroke patients in the next few years

    A Discrete Four Stroke Quantum Heat Engine Exploring the Origin of Friction

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    The optimal power performance of a first principle quantum heat engine model shows friction-like phenomena when the internal fluid Hamiltonian does not commute with the external control field. The model is based on interacting two-level-systems where the external magnetic field serves as a control variable.Comment: 4 pages 3 figure

    Evolution of Directed Triangle Motifs in the Google+ OSN

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    Motifs are a fundamental building block and distinguishing feature of networks. While characteristic motif distribution have been found in many networks, very little is known today about the evolution of network motifs. This paper studies the most important motifs in social networks, triangles, and how directed triangle motifs change over time. Our chosen subject is one of the largest Online Social Networks, Google+. Google+ has two distinguishing features that make it particularly interesting: (1) it is a directed network, which yields a rich set of triangle motifs, and (2) it is a young and fast evolving network, whose role in the OSN space is still not fully understood. For the purpose of this study, we crawled the network over a time period of six weeks, collecting several snapshots. We find that some triangle types display significant dynamics, e.g., for some specific initial types, up to 20% of the instances evolve to other types. Due to the fast growth of the OSN in the observed time period, many new triangles emerge. We also observe that many triangles evolve into less-connected motifs (with less edges), suggesting that growth also comes with pruning. We complement the topological study by also considering publicly available user profile data (mostly geographic locations). The corresponding results shed some light on the semantics of the triangle motifs. Indeed, we find that users in more symmetric triangle motifs live closer together, indicating more personal relationships. In contrast, asymmetric links in motifs often point to faraway users with a high in-degree (celebrities)

    Changes in vegetation spectra with deterioration of leaves under two methods of preservation

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    An experiment to measure changes in leaf spectra under different methods of preservation over time was conducted. The spectral measurements were made by a three band hand held radiometer which simulated three Thematic Mapper (TM) bands: TM3, TM4, and TM5. Daily spectral measurements of white oak leaves under three preservation treatments were made. The spectral readings over three treatments (fresh, bottled, and bagged vegetation) were indistinguishable in bands TM3 and TM5 for up to 4 days after collection. After that time bagged and bottled samples showed significant increases in reflected energy caused by loss of chlorophyll from and dehydration of the vegetation. No significant variation in the reflectance values from TM4 over preservation type for the experimental period was observed

    Bloch oscillations of Bose-Einstein condensates: Breakdown and revival

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    We investigate the dynamics of Bose-Einstein condensates (BEC) in a tilted one-dimensional periodic lattice within the mean-field (Gross-Pitaevskii) description. Unlike in the linear case the Bloch oscillations decay because of nonlinear dephasing. Pronounced revival phenomena are observed. These are analyzed in detail in terms of a simple integrable model constructed by an expansion in Wannier-Stark resonance states. We also briefly discuss the pulsed output of such systems for stronger static fields.Comment: RevTeX4, 9 pages, 14 figure

    The eta-photon transition form factor

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    The eta-photon transition form factor is evaluated in a formalism based on a phenomenological description at low values of the photon virtuality, and a QCD-based description at high photon virtualities, matching at a scale Q02Q_{0}^{2}. The high photon virtuality description makes use of a Distribution Amplitude calculated in the Nambu-Jona-Lasinio model with Pauli-Villars regularization at the matching scale Q02Q_{0}^{2}, and QCD evolution from Q02Q_{0}^{2} to higher values of Q2Q^{2}. A good description of the available data is obtained. The analysis indicates that the recent data from the BaBar collaboration on pion and eta transition form factor can be well reproduced, if a small contribution of twist three at the matching scale Q02Q_{0}^{2} is included.Comment: 14 pages, 3 figures, revised version, minor corrections, references added, conclusions unchanged. Accepted for publication in Phys. Rev.

    Hyperatlas: A New Framework for Image Federation

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    Hyperatlas is an open standard intended to facilitate the large-scale federation of image-based data. The subject of hyperatlas is the space of sphere-to-plane projection mappings (the FITS-WCS information), and the standard consists of coherent collections of these on which data can be resampled and thereby federated with other image data. We hope for a distributed effort that will produce a multi-faceted image atlas of the sky, made by federating many different surveys at different wavelengths and different times. We expect that hyperatlas-compliant imagery will be published and discovered through an International Virtual Observatory Alliance (IVOA) registry, and that grid-based services will emerge for the required resampling and mosaicking.Comment: Published in ADASS XIII proceeding

    Ground State Entropy in Potts Antiferromagnets and Chromatic Polynomials

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    We discuss recent results on ground state entropy in Potts antiferromagnets and connections with chromatic polynomials. These include rigorous lower and upper bounds, Monte Carlo measurements, large--qq series, exact solutions, and studies of analytic properties. Some related results on Fisher zeros of Potts models are also mentioned.Comment: LATTICE98(spin) 3 pages, Late
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