1,096 research outputs found

    Economic analysis of climate change adaptation strategies in selected coastal areas in Indonesia, Philippines and Vietnam

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    This report is an account of a cross-country study that covered Vietnam, Indonesia and the Philippines. Covering four sites (one each in Indonesia and Vietnam) and two sites in the Philippines, the study documented the impacts of three climate hazards affecting coastal communities, namely typhoon/flooding, coastal erosion and saltwater intrusion. It also analyzed planned adaptation options, which communities and local governments can implement, as well as autonomous responses of households to protect and insure themselves from these hazards. It employed a variety of techniques, ranging from participatory based approaches such as community hazard mapping and Focus Group Discussions (FGDs) to regression techniques, to analyze the impact of climate change and the behavior of affected communities and households

    Co-precipitation synthesis of nickel-rich cathodes for Li-ion batteries

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    The preparation of Ni-rich cathode materials is challenging due to the Ni2+ ion sensitivity to oxidation during synthesis. The synthesis conditions during the manufacture of Ni-rich materials such as LiNi0.8Mn0.1Co0.1O2 (NMC811) therefore require stringent control. The co-precipitation step, applied in the synthesis of the metal hydroxide precursor, determines the secondary particle assembly formation, where it is typically desirable to produce uniform, spherical, ∼10μm-diameter structures. A stirred tank reactor is often employed to maintain a constant temperature of 60 °C and a controlled pH of between 10.5 and 11.5 in an inert atmosphere to maintain a high Ni2+/Ni3+ ion ratio. This promotes the formation of an NMC hydroxide precursor (NixMnyCoz(OH)2) which is typically milled with a lithium salt and calcined to form LiNixMnyCozO2 with a layered α-NaFeO2 crystalline structure. This review outlines some of the critical synthetic parameters for the formation of spherical secondary assemblies of metal hydroxide precursors for nickel-rich layered cathodes

    Dynamic splitting of a Bose-Einstein Condensate

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    We study the dynamic process of splitting a condensate by raising a potential barrier in the center of a harmonic trap. We use a two-mode model to describe the phase coherence between the two halves of the condensate. Furthermore, we explicitly consider the spatial dependence of the mode funtions, which varies depending on the potential barrier. This allows to get the tunneling coupling between the two wells and the on-site energy as a function of the barrier height. Moreover we can get some insight on the collective modes which are excited by raising the barrier. We describe the internal and external degrees of freedom by variational ansatz. We distinguish the possible regimes as a function of the characteristic parameters of the problem and identify the adiabaticity conditions.Comment: 17 pages, 8 figure

    Statistical Analysis of Different Muon-antineutrino->Electron-antineutrino Searches

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    A combined statistical analysis of the experimental results of the LSND and KARMEN \numubnueb oscillation search is presented. LSND has evidence for neutrino oscillations that is not confirmed by the KARMEN experiment. This joint analysis is based on the final likelihood results for both data sets. A frequentist approach is applied to deduce confidence regions. At a combined confidence level of 36%, there is no area of oscillation parameters compatible with both experiments. For the complementary confidence of 1-0.36=64%, there are two well defined regions of oscillation parameters (sin^2(2th),Dm^2) compatible with both experiments.Comment: 25 pages, including 10 figures, submitted to Phys. Rev.

    Flavor changing Z-decays from scalar interactions at a Giga-Z Linear Collider

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    The flavor changing decay Z -> d_I \bar{d}_J is investigated with special emphasis on the b \bar{s} final state. Various models for flavor violation are considered: two Higgs doublet models (2HDM's), supersymmetry (SUSY) with flavor violation in the up and down-type squark mass matrices and SUSY with flavor violation mediated by R-parity-violating interaction. We find that, within the SUSY scenarios for flavor violation, the branching ratio for the decay Z -> b \bar{s} can reach 10^{-6} for large \tan\beta values, while the typical size for this branching ratio in the 2HDM's considered is about two orders of magnitudes smaller at best. Thus, flavor changing SUSY signatures in radiative Z decays such as Z -> b \bar{s} may be accessible to future ``Z factories'' such as a Giga-Z version of the TESLA design.Comment: 27 pages, 15 figures, REVTeX4. A new section added and a few minor corrections were made in the tex

    Hybrid Stars in a Strong Magnetic Field

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    We study the effects of high magnetic fields on the particle population and equation of state of hybrid stars using an extended hadronic and quark SU(3) non-linear realization of the sigma model. In this model the degrees of freedom change naturally from hadrons to quarks as the density and/or temperature increases. The effects of high magnetic fields and anomalous magnetic moment are visible in the macroscopic properties of the star, such as mass, adiabatic index, moment of inertia, and cooling curves. Moreover, at the same time that the magnetic fields become high enough to modify those properties, they make the star anisotropic.Comment: Revised version with updated reference

    Phenomenology of Randall-Sundrum Black Holes

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    We explore the phenomenology of microscopic black holes in the S1/Z2S^1/Z_2 Randall-Sundrum (RS) model. We consider the canonical framework in which both gauge and matter fields are confined to the brane and only gravity spills into the extra dimension. The model is characterized by two parameters, the mass of the first massive graviton (m1)(m_1), and the curvature 1/â„“1/\ell of the RS anti-de Sitter space. We compute the sensitivity of present and future cosmic ray experiments to various regions of â„“\ell and m1,m_1, and compare with that of Runs I and II at the Tevatron. As part of our phenomenological analysis, we examine constraints placed on â„“\ell by AdS/CFT considerations.Comment: Version to appear in Physical Review D; contains additional analysis on sensitivity of OW

    Extracting Br(omega->pi^+ pi^-) from the Time-like Pion Form-factor

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    We extract the G-parity-violating branching ratio Br(omega->pi^+ pi^-) from the effective rho-omega mixing matrix element Pi_{rho omega}(s), determined from e^+e^- -> pi^+ pi^- data. The omega->pi^+ pi^- partial width can be determined either from the time-like pion form factor or through the constraint that the mixed physical propagator D_{rho omega}^{mu nu}(s) possesses no poles. The two procedures are inequivalent in practice, and we show why the first is preferred, to find finally Br(omega->pi^+ pi^-) = 1.9 +/- 0.3%.Comment: 12 pages (published version

    String-localized Quantum Fields and Modular Localization

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    We study free, covariant, quantum (Bose) fields that are associated with irreducible representations of the Poincar\'e group and localized in semi-infinite strings extending to spacelike infinity. Among these are fields that generate the irreducible representations of mass zero and infinite spin that are known to be incompatible with point-like localized fields. For the massive representation and the massless representations of finite helicity, all string-localized free fields can be written as an integral, along the string, of point-localized tensor or spinor fields. As a special case we discuss the string-localized vector fields associated with the point-like electromagnetic field and their relation to the axial gauge condition in the usual setting.Comment: minor correction
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