67 research outputs found

    Greenberger-Horne-Zeilinger nonlocality for continuous variable systems

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    As a development of our previous work, this paper is concerned with the Greenberger-Horne-Zeilinger (GHZ) nonlocality for continuous variable cases. The discussion is based on the introduction of a pseudospin operator, which has the same algebra as the Pauli operator, for each of the NN modes of a light field. Then the Bell-CHSH (Clauser, Horne, Shimony and Holt) inequality is presented for the NN modes, each of which has a continuous degree of freedom. Following Mermin's argument, it is demonstrated that for NN-mode parity-entangled GHZ states (in an infinite-dimensional Hilbert space) of the light field, the contradictions between quantum mechanics and local realism grow exponentially with NN, similarly to the usual NN-spin cases.Comment: RevTEX; comments are welcomed; new version with minor change

    Quantum singularities in a model of f(R) Gravity

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    The formation of a naked singularity in a model of f(R) gravity having as source a linear electromagnetic field is considered in view of quantum mechanics. Quantum test fields obeying the Klein-Gordon, Dirac and Maxwell equations are used to probe the classical timelike naked singularity developed at r=0. We prove that the spatial derivative operator of the fields fails to be essentially self-adjoint. As a result, the classical timelike naked singularity remains quantum mechanically singular when it is probed with quantum fields having different spin structures.Comment: 12 pages, final version. Accepted for publication in EPJ

    Geometric and thermodynamic properties in Gauss-Bonnet gravity

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    In this paper, the generalized second law (GSL) of thermodynamics and entropy is revisited in the context of cosmological models in Gauss-Bonnet gravity with the boundary of the universe is assumed to be enclosed by the dynamical apparent horizon. The model is best fitted with the observational data for distance modulus. The best fitted geometric and thermodynamic parameters such as equation of state parameter, deceleration parameter and entropy are derived. To link between thermodynamic and geometric parameters, the "entropy rate of change multiplied by the temperature" as a model independent thermodynamic state parameter is also derived. The results show that the model is in good agreement with the observational analysis.Comment: 13 pages, 13 figures, to be published in Astrophysics and Space Sc

    Entropy and statefinder diagnosis in chameleon cosmology

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    In this paper, the generalized second law (GSL) of thermodynamics and entropy is revisited in the context of cosmological models with bouncing behavior such as chameleon cosmology where the boundary of the universe is assumed to be enclosed by the dynamical apparent horizon. From a thermodynamic point of view, to link between thermodynamic and geometric parameters in cosmological models, we introduce "entropy rate of change multiplied by the temperature" as a model independent thermodynamic state parameter together with the well known {r,s}\{r,s \} statefinder to differentiate the dark energy models.Comment: 11 pages, 5 figures. will be published in Astrophys. Space Sc

    Reporting guideline for the early stage clinical evaluation of decision support systems driven by artificial intelligence: DECIDE-AI

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    A growing number of artificial intelligence (AI)-based clinical decision support systems are showing promising performance in preclinical, in silico, evaluation, but few have yet demonstrated real benefit to patient care. Early stage clinical evaluation is important to assess an AI system’s actual clinical performance at small scale, ensure its safety, evaluate the human factors surrounding its use, and pave the way to further large scale trials. However, the reporting of these early studies remains inadequate. The present statement provides a multistakeholder, consensus-based reporting guideline for the Developmental and Exploratory Clinical Investigations of DEcision support systems driven by Artificial Intelligence (DECIDE-AI). We conducted a two round, modified Delphi process to collect and analyse expert opinion on the reporting of early clinical evaluation of AI systems. Experts were recruited from 20 predefined stakeholder categories. The final composition and wording of the guideline was determined at a virtual consensus meeting. The checklist and the Explanation & Elaboration (E&E) sections were refined based on feedback from a qualitative evaluation process. 123 experts participated in the first round of Delphi, 138 in the second, 16 in the consensus meeting, and 16 in the qualitative evaluation. The DECIDE-AI reporting guideline comprises 17 AI specific reporting items (made of 28 subitems) and 10 generic reporting items, with an E&E paragraph provided for each. Through consultation and consensus with a range of stakeholders, we have developed a guideline comprising key items that should be reported in early stage clinical studies of AI-based decision support systems in healthcare. By providing an actionable checklist of minimal reporting items, the DECIDE-AI guideline will facilitate the appraisal of these studies and replicability of their findings

    Measurement of coherent π+π^{+} production in low energy neutrino-Carbon scattering

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    We report the first measurement of the flux-averaged cross section for charged current coherent π+\pi^{+} production on carbon for neutrino energies less than 1.5 GeV to a restricted final state phase space region in the T2K near detector, ND280. Comparisons are made with predictions from the Rein-Sehgal coherent production model and the model by Alvarez-Ruso {\it et al.}, the latter representing the first implementation of an instance of the new class of microscopic coherent models in a neutrino interaction Monte Carlo event generator. This results contradicts the null results reported by K2K and SciBooNE in a similar neutrino energy region

    The Physics of the B Factories

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    Flow regime and bedforms in a ridge and runnel system, S.E. Spain

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    During landward migration, ridge and runnel systems are subjected to asymmetric oscillatory and/or unidirectional flow regimes, depending on the stage of development reached by these systems. In the early stages of evolution, when the ridge is situated in the upper shoreface, the whole system is subjected to asymmetric oscillatory flow. The runnel is under lower flow regime conditions and the ridge may be under upper or lower flow regime according to water depth and wave energy. Later, when the ridge has migrated to a position on the foreshore, the runnel is largely under a unidirectional lower flow regime while the ridge itself is under oscillatory upper flow regime. When the ridge welds to berm, it is largely emergent and exposed to high-tide swash action under upper flow regime conditions. The runnel is eventually filled with sand and transformed into a low-lying area. All these types grade laterally into each other. One or more ridge and runnel systems can occur at the same time. Wave energy, tide level and position of the ridge control the variations in the characteristics of the ridge and also the position of the zones of bedforms found at the upper shorefac
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