6,414 research outputs found

    The possible role of hybridization in adaptive radiations

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    Determinants of local responsiveness of FMNCS in mainland China

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    Recent regulations, associated with China’s accession to the World Trade Organisation (WTO), specifically Decree 113 and Decree 114, have largely changed the situation for foreign multinational construction companies (FMNCs) operating in mainland China. A field investigation has identified that local responsiveness is critical for FMNCs to survive and develop in the complicated and uncertain Chinese construction industry. Government policy, China-specific construction industrial factors and increasing competition intensity imposed by local competitors are recognized as the major determinants driving local responsiveness of FMNCs. This study has also examined that localisation of internal resources, establishment of local networks and cooperation or strategic alliances with local contractors and design institutes are the key local adaptation strategies for FMNCs operating in mainland China

    The General Primordial Cosmic Perturbation

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    We consider the most general primordial cosmological perturbation in a universe filled with photons, baryons, neutrinos, and a hypothetical cold dark matter (CDM) component within the framework of linearized perturbation theory. We give a careful discussion of the different allowed modes, distinguishing modes which are regular at early times, singular at early times, or pure gauge. As well as the familiar growing and decaying adiabatic modes and the baryonic and CDM isocurvature modes we identify two {\it neutrino isocurvature} modes which do not seem to have been discussed before. In the first, the ratio of neutrinos to photons varies spatially but the net density perturbation vanishes. In the second the photon-baryon plasma and the neutrino fluid have a spatially varying relative bulk velocity, balanced so that the net momentum density vanishes. Possible mechanisms which could generate the two neutrino isocurvature modes are discussed. If one allows the most general regular primordial perturbation, all quadratic correlators of observables such as the microwave background anisotropy and matter perturbations are completely determined by a 5×5,5\times 5, real, symmetric matrix-valued function of co-moving wavenumber. In a companion paper we examine prospects for detecting or constraining the amplitudes of the most general allowed regular perturbations using present and future CMB data.Comment: 18 pages, 2 Postscript figures, uses revtex. Revised 2-2000 Minor errors corrected and some references adde

    Constraining Isocurvature Perturbations with CMB Polarization

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    The role of cosmic microwave background (CMB) polarisation data in constraining the presence of primordial isocurvature modes is examined. While the MAP satellite mission will be unable to simultaneously constrain isocurvature modes and cosmological parameters, the PLANCK mission will be able to set strong limits on the presence of isocurvature modes if it makes a precise measurement of the CMB polarisation sky. We find that if we allow for the possible presence of isocurvature modes, the recently obtained BOOMERANG measurement of the curvature of the universe fails. However, a comparably sensitive polarisation measurement on the same angular scales will permit a determination of the curvature of the universe without the prior assumption of adiabaticity.Comment: 4pages, Latex with four eps figures. (Revised 18 Dec 2000. Minor typos corrected

    When does a major outbreak become a Public Health Emergency of International Concern?

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    The process of determining whether a Public Health Emergencies of International Concern (PHEIC) exists and should be declared has drawn increasing criticism over the past few years with allegations that it is more political than technical. Delaying declaration, where appropriate, means that the opportunity of garnering international solidarity and necessary resources in the early phases of epidemics, when public health measures may be more effective, is lost. A reform agenda aimed at enhancing WHO/Emergency Committee transparency and objectivity for the PHEIC declaration process is required

    Observing the Sunyaev-Zel'dovich Effect Closer to Home

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    Hot gas trapped in a dark matter halo will produce a decrement in the surface brightness of the microwave background, the Sunyaev-Zel'dovich (SZ) effect. While massive clusters produce the strongest central SZ decrements, we point out that a local galaxy halo, specifically the halo of M31, may be one of the brightest integrated SZ sources in the sky. For various realistic gas distributions consistent with current X-ray limits, we show that the integrated SZ decrement from M31 will be comparable to decrements already detected in more distant sources, provided its halo contains an appreciable quantity of hot gas. A measurement of this decrement would provide direct information on the mass, spatial distribution and thermodynamic state of hot gas in a low-mass halo, and could place important constraints on current models of galaxy formation. Detecting such an extended (~ 10 degree), low-amplitude signal will be challenging, but should be possible with all-sky SZ maps from satellite missions such as the Wilkinson Microwave Anisotropy Probe or the Planck Surveyor.Comment: 5 pages, 3 figures; submitted to MNRA
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