118,723 research outputs found

    Holographic dark energy model with non-minimal coupling

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    We find that holographic dark energy model with non-minimally coupled scalar field gives rise to an accelerating universe by choosing Hubble scale as IR cutoff. We show viable range of a non-minimal coupling parameter in the framework of this model.Comment: 7 pages, no figure, corrected some typos, to be published in Europhys. Let

    TandemNet: Distilling Knowledge from Medical Images Using Diagnostic Reports as Optional Semantic References

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    In this paper, we introduce the semantic knowledge of medical images from their diagnostic reports to provide an inspirational network training and an interpretable prediction mechanism with our proposed novel multimodal neural network, namely TandemNet. Inside TandemNet, a language model is used to represent report text, which cooperates with the image model in a tandem scheme. We propose a novel dual-attention model that facilitates high-level interactions between visual and semantic information and effectively distills useful features for prediction. In the testing stage, TandemNet can make accurate image prediction with an optional report text input. It also interprets its prediction by producing attention on the image and text informative feature pieces, and further generating diagnostic report paragraphs. Based on a pathological bladder cancer images and their diagnostic reports (BCIDR) dataset, sufficient experiments demonstrate that our method effectively learns and integrates knowledge from multimodalities and obtains significantly improved performance than comparing baselines.Comment: MICCAI2017 Ora

    Information on the Pion Distribution Amplitude from the Pion-Photon Transition Form Factor with the Belle and BaBar Data

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    The pion-photon transition form factor (TFF) provides strong constraints on the pion distribution amplitude (DA). We perform an analysis of all existing data (CELLO, CLEO, BaBar, Belle) on the pion-photon TFF by means of light-cone pQCD approach in which we include the next-to-leading order correction to the valence-quark contribution and estimate the non-valence-quark contribution by a phenomenological model based on the TFF's limiting behavior at both Q2→0Q^2\to 0 and Q2→∞Q^2\to\infty. At present, the pion DA is not definitely determined, it is helpful to have a pion DA model that can mimic all the suggested behaviors, especially to agree with the constraints from the pion-photon TFF in whole measured region within a consistent way. For the purpose, we adopt the conventional model for pion wavefunction/DA that has been constructed in our previous paper \cite{hw1}, whose broadness is controlled by a parameter BB. We fix the DA parameters by using the CELLO, CLEO, BABAR and Belle data within the smaller Q2Q^2 region (Q2≤15Q^2 \leq 15 GeV2^2), where all the data are consistent with each other. And then the pion-photon TFF is extrapolated into larger Q2Q^2 region. We observe that the BABAR favors B=0.60B=0.60 which has the behavior close to the Chernyak-Zhitnitsky DA, whereas the recent Belle favors B=0.00B=0.00 which is close to the asymptotic DA. We need more accurate data at large Q2Q^2 region to determine the precise value of BB, and the definite behavior of pion DA can be concluded finally by the consistent data in the coming future.Comment: 6 pages, 5 figures. Slightly changed and references update

    Transverse momentum dependence in the perturbative calculation of pion form factor

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    By reanalysing transverse momentum dependence in the perturbative calculation of pion form factor an improved expression of pion form factor which takes into account the transverse momentum dependenc in hard scattering amplitude and intrinsic transverse momentum dependence associated with pion wave functions is given to leading order, which is available for momentum transfers of the order of a few GeV as well as for Q→∞Q \to \infty. Our scheme can be extended to evaluate the contributions to the pion form factor beyond leading order.Comment: 13 pages in LaTeX, plus 3 Postscript figure

    Close binary evolution I. The tidally induced shear mixing in rotating binaries

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    We study how tides in a binary system induce some specific internal shear mixing, able to substantially modify the evolution of close binaries prior to mass transfer. We construct numerical models accounting for tidal interactions, meridional circulation, transport of angular momentum, shears and horizontal turbulence and consider a variety of orbital periods and initial rotation velocities. Depending on orbital periods and rotation velocities, tidal effects may spin down (spin down Case) or spin up (spin up Case) the axial rotation. In both cases, tides may induce a large internal differential rotation. The resulting tidally induced shear mixing (TISM) is so efficient that the internal distributions of angular velocity and chemical elements are greatly influenced. The evolutionary tracks are modified, and in both cases of spin down and spin up, large amounts of nitrogen can be transported to the stellar surfaces before any binary mass transfer. Meridional circulation, when properly treated as an advection, always tends to counteract the tidal interaction, tending to spin up the surface when it is braked down and vice versa. As a consequence, the times needed for the axial angular velocity to become equal to the orbital angular velocity may be larger than given by typical synchronization timescales. Also, due to meridional circulation some differential rotation remains in tidally locked binary systems.Comment: 10 pages, 18 figures, Accepted for publication in Astronomy and Astrophysic

    Gravitational Correction and Weak Gravity Conjecture

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    We consider the gravitational correction to the running of gauge coupling. Weak gravity conjecture implies that the gauge theories break down when the gravitational correction becomes greater than the contribution from gauge theories. This observation can be generalized to non-Abelian gauge theories in diverse dimensions and the cases with large extra dimensions.Comment: 8 pages; minor correction and refs adde
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