660 research outputs found

    The sign of the day-night asymmetry for solar neutrinos

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    A qualitative understanding of the day-night asymmetry for solar neutrinos is provided. The greater night flux in nu_e is seen to be a consequence of the fact that the matter effect in the sun and that in the earth have the same sign. It is shown in the adiabatic approximation for the sun that for all values of the mixing angle theta_V between 0 and pi/2, the night flux of neutrinos is greater than the day flux. Only for small values of theta_V where the adiabatic approximation badly fails does the sign of the day-night asymmetry reverse.Comment: 3 pages, 3 figures, typos corrected and references adde

    China’s livestock transition: Driving forces, impacts, and consequences

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    China’s livestock industry has experienced a vast transition during the last three decades, with profound effects on domestic and global food provision, resource use, nitrogen and phosphorus losses, and greenhouse gas (GHG) emissions. We provide a comprehensive analysis of the driving forces around this transition and its national and global consequences. The number of livestock units (LUs) tripled in China in less than 30 years, mainly through the growth of landless industrial livestock production systems and the increase in monogastric livestock (from 62 to 74% of total LUs). Changes were fueled through increases in demand as well as, supply of new breeds, new technology, and government support. Production of animal source protein increased 4.9 times, nitrogen use efficiency at herd level tripled, and average feed use and GHG emissions per gram protein produced decreased by a factor of 2 between 1980 and 2010. In the same period, animal feed imports have increased 49 times, total ammonia and GHG emissions to the atmosphere doubled, and nitrogen losses to watercourses tripled. As a consequence, China’s livestock transition has significant global impact. Forecasts for 2050, using the Shared Socio-economic Pathways scenarios, indicate major further changes in livestock production and impacts. On the basis of these possible trajectories, we suggest an alternative transition, which should be implemented by government, processing industries, consumers, and retailers. This new transition is targeted to increase production efficiency and environmental performance at system level, with coupling of crop-livestock production, whole chain manure management, and spatial planning as major components

    Impacts of environmental factors and human disturbance on composition of roadside vegetation in Xishuangbanna National Nature Reserve of Southwest China

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    AbstractVegetation-disturbance-environment relationships in Xishuangbanna Nature Reserve (XNR) was examined using multivariate analysis to understand the impacts of environmental factors and human disturbance on vegetation along the highway corridor. The results show that native forests were the best habitat for protected/endangered species and native species. The exotic plants Eupatorium odoratum and Eupatorium adenophora were found primarily in secondary forests and their presence was positively associated with altitude and soil potassium concentrations. The distribution of two protected plants, Phoebe nanmu and Pometia tomentosa, was negatively associated with road disturbance. Understanding the complex effects of environmental factors and human disturbance is key for developing conservation and restoration strategies for roadside plant ecosystems

    Entropy Function for Non-Extremal Black Holes in String Theory

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    We generalize the entropy function formalism to five-dimensional and four-dimensional non-extremal black holes in string theory. In the near horizon limit, these black holes have BTZ metric as part of the spacetime geometry. It is shown that the entropy function formalism also works very well for these non-extremal black holes and it can reproduce the Bekenstein-Hawking entropy of these black holes in ten dimensions and lower dimensions.Comment: 19 pages, no figure, JHEP3 style, to appear in JHE

    Comparison of s- and d-wave gap symmetry in nonequilibrium superconductivity

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    Recent application of ultrafast pump/probe optical techniques to superconductors has renewed interest in nonequilibrium superconductivity and the predictions that would be available for novel superconductors, such as the high-Tc cuprates. We have reexamined two of the classical models which have been used in the past to interpret nonequilibrium experiments with some success: the mu* model of Owen and Scalapino and the T* model of Parker. Predictions depend on pairing symmetry. For instance, the gap suppression due to excess quasiparticle density n in the mu* model, varies as n^{3/2} in d-wave as opposed to n for s-wave. Finally, we consider these models in the context of S-I-N tunneling and optical excitation experiments. While we confirm that recent pump/probe experiments in YBCO, as presently interpreted, are in conflict with d-wave pairing, we refute the further claim that they agree with s-wave.Comment: 14 pages, 11 figure

    On Entropy Function for Supersymmetric Black Rings

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    The entropy function for five-dimensional supersymmetric black rings, which are solutions of U(1)3U(1)^{3} minimal supergravity, is calculated via both on-shell and off-shell formalism. We find that at the tree level, the entropy function obtained from both perspectives can reproduce the Bekenstein-Hawking entropy. We also compute the higher order corrections to the entropy arising form five-dimensional Gauss-Bonnet term as well as supersymmetric R2R^{2} completion respectively and compare the results with previous microscopic calculations.Comment: 17 pages, no figure, JHEP3 style, to appear in JHEP

    A Model of Fermion Masses and Flavor Mixings with Family Symmetry SU(3)U(1)SU(3)\otimes U(1)

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    The family symmetry SU(3)U(1)SU(3)\otimes U(1) is proposed to solve flavor problems about fermion masses and flavor mixings. It's breaking is implemented by some flavon fields at the high-energy scale. In addition a discrete group Z2Z_{2} is introduced to generate tiny neutrino masses, which is broken by a real singlet scalar field at the middle-energy scale. The low-energy effective theory is elegantly obtained after all of super-heavy fermions are integrated out and decoupling. All the fermion mass matrices are regularly characterized by four fundamental matrices and thirteen parameters. The model can perfectly fit and account for all the current experimental data about the fermion masses and flavor mixings, in particular, it finely predicts the first generation quark masses and the values of θ13l\theta^{\,l}_{13} and JCPlJ_{CP}^{\,l} in neutrino physics. All of the results are promising to be tested in the future experiments.Comment: 14 pages, 1 figure, to make a few of corrections to the old version. arXiv admin note: substantial text overlap with arXiv:1011.457

    Novel Structure Function for Photon Fragmentation into a Λ\Lambda Hyperon and Transverse Λ\Lambda Polarization in Unpolarized Electron-Positron Annihilation

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    The possibility is examined for the inclusive Λ\Lambda in unpolarized electron-positron annihilation to be transversely polarized. Due to final-state interactions, there exists a novel structure function F^(z,Q2)\hat F(z,Q^2) for the inclusive Λ\Lambda hyperon (or any other baryons) production from the unpolarized time-like photon fragmentation, which makes contribution to the transverse Λ\Lambda polarization in the unpolarized electron-positron annihilation.Comment: RevTex, 4 pages, the version appearing in Phys. Rev.

    Effective Lagrangian for sˉbg\bar{s}bg and sˉbγ\bar{s}b\gamma Vertices in the mSUGRA model

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    Complete expressions of the sˉbg\bar{s}bg and sˉbγ\bar{s}b\gamma vertices are derived in the framework of supersymmetry with minimal flavor violation. With the minimal supergravity (mSUGRA) model, a numerical analysis of the supersymmetric contributions to the Wilson Coefficients at the weak scale is presented.Comment: 12 pages + 7 ps figures, Late

    A Note on Exact Solutions and Attractor Mechanism for Non-BPS Black Holes

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    We obtain two extremal, spherically symmetric, non-BPS black hole solutions to 4D supergravity, one of which carries D2-D6 charges and the other carries D0-D2-D4 charges. For the D2-D6 case, rather than solving the equations of motion directly, we assume the form of the solution and then find that the assumption satisfies the equations of motion and the constraint. Our D2-D6 solution is manifestly dual to the solution presented in 0710.4967. The D0-D2-D4 solution is obtained by performing certain [SL(2,Z)]3[SL(2,{\bf Z})]^{3} duality transformations on the D0-D4 solution in 0710.4967.Comment: 20 pages, LaTe
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