2,639 research outputs found

    Magnetic Field Generation from Self-Consistent Collective Neutrino-Plasma Interactions

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    A new Lagrangian formalism for self-consistent collective neutrino-plasma interactions is presented in which each neutrino species is described as a classical ideal fluid. The neutrino-plasma fluid equations are derived from a covariant relativistic variational principle in which finite-temperature effects are retained. This new formalism is then used to investigate the generation of magnetic fields and the production of magnetic helicity as a result of collective neutrino-plasma interactions.Comment: 23 page

    HRM in Multinationals’ Operations in China: Business, People, and HR Issues

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    This paper presents the results of a study on the HR function in the Chinese operations of large multinational companies. Surveys of both line and HR executives in these firms were conducted. Results reveal that line executives are more sensitive than HR executives to criticality of people management issues as business issues, and that they see HR\u27s strategic orientation as the most critical area for improvement. The challenges and opportunities implied by these results are discussed

    Aleph_null Hypergravity in Three-Dimensions

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    We construct hypergravity theory in three-dimensions with the gravitino \psi_{\mu m_1... m_n}{}^A with an arbitrary half-integral spin n+3/2, carrying also the index A for certain real representations of any gauge group G. The possible real representations are restricted by the condition that the matrix representation of all the generators are antisymmetric: (T^I)^{A B} = - (T^I)^{B A}. Since such a real representation can be arbitrarily large, this implies \aleph_0-hypergravity with infinitely many (\aleph_0) extended local hypersymmetries.Comment: 12 pages, no figure

    Non-Abelian Tensors with Consistent Interactions

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    We present a systematic method for constructing consistent interactions for a tensor field of an arbitrary rank in the adjoint representation of an arbitrary gauge group in any space-time dimensions. This method is inspired by the dimensional reduction of Scherk-Schwarz, modifying field strengths with certain Chern-Simons forms, together with modified tensorial gauge transformations. In order to define a consistent field strength of a r-rank tensor B_{\mu_1...\mu_r}^I in the adjoint representation, we need the multiplet (B_{\mu_1...\mu_r}^I, B_{\mu_1...\mu_{r-1}}^{I J}, ..., B_\mu^{I_1...I_r}, B^{I_1... I_{r+1}}). The usual problem of consistency of the tensor field equations is circumvented in this formulation.Comment: 15 pages, no figure

    High-Energy Neutrino Signatures of Dark Matter Decaying into Leptons

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    Decaying dark matter has previously been proposed as a possible explanation for the excess high energy cosmic ray electrons and positrons seen by PAMELA and the Fermi Gamma-Ray Space Telescope (FGST). To accommodate these signals however, the decays must be predominantly leptonic, to muons or taus, and therefore produce neutrinos, potentially detectable with the IceCube neutrino observatory. We find that, with five years of data, IceCube (supplemented by DeepCore) will be able to significantly constrain the relevant parameter space of decaying dark matter, and may even be capable of discovering dark matter decaying in the halo of the Milky Way.Comment: 4 pages, 1 figur

    Dilaton and Second-Rank Tensor Fields as Supersymmetric Compensators

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    We formulate a supersymmetric theory in which both a dilaton and a second-rank tensor play roles of compensators. The basic off-shell multiplets are a linear multiplet (B_{\mu\nu}, \chi, \phi) and a vector multiplet (A_\mu, \l; C_{\mu\nu\rho}), where \phi and B_{\m\n} are respectively a dilaton and a second-rank tensor. The third-rank tensor C_{\mu\nu\rho} in the vector multiplet is 'dual' to the conventional D-field with 0 on-shell or 1 off-shell degree of freedom. The dilaton \phi is absorbed into one longitudinal component of A_\mu, making it massive. Initially, B_{\mu\nu} has 1 on-shell or 3 off-shell degrees of freedom, but it is absorbed into the longitudinal components of C_{\mu\nu\rho}. Eventually, C_{\mu\nu\rho} with 0 on-shell or 1 off-shell degree of freedom acquires in total 1 on-shell or 4 off-shell degrees of freedom, turning into a propagating massive field. These basic multiplets are also coupled to chiral multiplets and a supersymmetric Dirac-Born-Infeld action. Some of these results are also reformulated in superspace. The proposed mechanism may well provide a solution to the long-standing puzzle of massless dilatons and second-rank tensors in supersymmetric models inspired by string theory.Comment: 15 pages, no figure

    Vascular endothelial growth factor directly inhibits primitive neural stem cell survival but promotes definitive neural stem cell survival

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    There are two types of neural stem cells (NSCs). Primitive NSCs [leukemia inhibitory factor (LIF) dependent but exogenous fibroblast growth factor (FGF) 2 independent] can be derived from mouse embryonic stem (ES) cells in vitro and from embryonic day 5.5 (E5.5) to E7.5 epiblast and E7.5-E8.5 neuroectoderm in vivo. Definitive NSCs (LIF independent but FGF2 dependent) first appear in the E8.5 neural plate and persist throughout life. Primitive NSCs give rise to definitive NSCs. Loss and gain of functions were used to study the role of vascular endothelial growth factor (VEGF)-A and its receptor, Flk1, in NSCs. The numbers of Flk1 knock-out mice embryo-derived and ES cell-derived primitive NSCs were increased because of the enhanced survival of primitive NSCs. In contrast, neural precursor-specific, Flk1 conditional knock-out mice-derived, definitive NSCs numbers were decreased because of the enhanced cell death of definitive NSCs. These effects were not observed in cells lacking Flt1, another VEGF receptor. In addition, the cell death stimulated by VEGF-A of primitive NSC and the cell survival stimulated by VEGF-A of definitive NSC were blocked by Flk1/Fc-soluble receptors and VEGF-A function-blocking antibodies. These VEGF-A phenotypes also were blocked by inhibition of the downstream effector nuclear factor kappa B (NF-kappa B). Thus, both the cell death of primitive NSC and the cell survival of definitive NSC induced by VEGF-A stimulation are mediated by bifunctional NF-kappa B effects. In conclusion, VEGF-A function through Flk1 mediates survival (and not proliferative or fate change) effects on NSCs, specifically
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