880 research outputs found

    Taking Care of Policy in Times of Crisis: Comparative Lessons from Belgium's Longest Caretaker Government

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    When the financial crisis hit the Eurozone, Belgium, along with several other countries, postponed its consolidation policies until after the general elections. What followed was the longest caretaker rule that any stable democracy had ever experienced. This article analyses the phenomenon of policy continuity and change during this double crisis. It illustrates how the exogenous economic crisis overrode the endogenous political crisis, showing the extent to which international policy determinants expanded the remit of caretaker policy-making. At the same time, our analysis of the nature of caretaker conventions, the nature of multi-level governance, the permanence of administrative personnel, and the re-invention of parliament offers opportunities to draw lessons and deepen comparative research on policy termination and maintenance in the face of crisis

    The Origin of Structures in Generalized Gravity

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    In a class of generalized gravity theories with general couplings between the scalar field and the scalar curvature in the Lagrangian, we can describe the quantum generation and the classical evolution of both the scalar and tensor structures in a simple and unified manner. An accelerated expansion phase based on the generalized gravity in the early universe drives microscopic quantum fluctuations inside a causal domain to expand into macroscopic ripples in the spacetime metric on scales larger than the local horizon. Following their generation from quantum fluctuations, the ripples in the metric spend a long period outside the causal domain. During this phase their evolution is characterized by their conserved amplitudes. The evolution of these fluctuations may lead to the observed large scale structures of the universe and anisotropies in the cosmic microwave background radiation.Comment: 5 pages, latex, no figur

    Intrinsic Geometry of a Null Hypersurface

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    We apply Cartan's method of equivalence to construct invariants of a given null hypersurface in a Lorentzian space-time. This enables us to fully classify the internal geometry of such surfaces and hence solve the local equivalence problem for null hypersurface structures in 4-dimensional Lorentzian space-times

    Black Holes with a Massive Dilaton

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    The modifications of dilaton black holes which result when the dilaton acquires a mass are investigated. We derive some general constraints on the number of horizons of the black hole and argue that if the product of the black hole charge QQ and the dilaton mass mm satisfies Qm<O(1)Q m < O(1) then the black hole has only one horizon. We also argue that for Qm>O(1)Q m > O(1) there may exist solutions with three horizons and we discuss the causal structure of such solutions. We also investigate the possible structures of extremal solutions and the related problem of two-dimensional dilaton gravity with a massive dilaton.Comment: 36 pages with 5 figures (as uuencoded compressed tar file) (revised version has one major change in bound on mass for extremal solution and minor typos fixed), harvma

    Black holes in the Brans-Dicke-Maxwell theory

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    The black hole solutions in the higher dimensional Brans-Dicke-Maxwell theory are investigated. We find that the presence of the nontrivial scalar field depends on the spacetime dimensions (D). When D=4, the solution corresponds to the Reissner-Nordstr\"{o}m black hole with a constant scalar field. In higher dimensions (D>4), one finds the charged black hole solutions with the nontrivial scalar field. The thermal properties of the charged black holes are discussed and the reason why the nontrivial scalar field exists are explained. Also the solutions for higher dimensional Brans-Dicke theory are given for comparison.Comment: Revtex, 5 pages, no figures, contents were rewritten and new references were adde

    Dark Energy, Induced Gravity and Broken Scale Invariance

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    We study the cosmological evolution of an induced gravity model with a self-interacting scalar field σ\sigma and in the presence of matter and radiation. Such model leads to Einstein Gravity plus a cosmological constant as a stable attractor among homogeneous cosmologies and is therefore a viable dark-energy (DE) model for a wide range of scalar field initial conditions and values for its positive γ\gamma coupling to the Ricci curvature γσ2R\gamma \sigma^{2}R.Comment: 6 pages, 5 figures, 1 table: final version accepted for publication in PL

    Singularity Free (Homogeneous Isotropic) Universe in Graviton-Dilaton Models

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    We present a class of graviton-dilaton models in which a homogeneous isotropic universe, such as our observed one, evolves with no singularity at any time. Such models may stand on their own as interesting models for singularity free cosmology, and may be studied further accordingly. They may also arise from string theory. We discuss critically a few such possibilities.Comment: 11 pages. Latex file. Revised in response to referees' Comments. Results remain same. To appear in Phys. Rev. Let

    Kinetic Inflation in Stringy and Other Cosmologies

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    An inflationary epoch driven by the kinetic energy density in a dynamical Planck mass is studied. In the conformally related Einstein frame it is easiest to see the demands of successful inflation cannot be satisfied by kinetic inflation alone. Viewed in the original Jordan-Brans-Dicke frame, the obstacle is manifest as a kind of graceful exit problem and/or a kind of flatness problem. These arguments indicate the weakness of only the simplest formulation. {}From them can be gleaned directions toward successful kinetic inflation.Comment: 26 pages, LaTeX, CITA-94-2

    A time-space varying speed of light and the Hubble Law in static Universe

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    We consider a hypothetical possibility of the variability of light velocity with time and position in space which is derived from two natural postulates. For the consistent consideration of such variability we generalize translational transformations of the Theory of Relativity. The formulae of transformations between two rest observers within one inertial system are obtained. It is shown that equality of velocities of two particles is as relative a statement as simultaneity of two events is. We obtain the expression for the redshift of radiation of a rest source which formally reproduces the Hubble Law. Possible experimental implications of the theory are discussed.Comment: 7 page

    Dilaton Black Holes with Electric Charge

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    Static spherically symmetric solutions of the Einstein-Maxwell gravity with the dilaton field are described. The solutions correspond to black holes and are generalizations of the previously known dilaton black hole solution. In addition to mass and electric charge these solutions are labeled by a new parameter, the dilaton charge of the black hole. Different effects of the dilaton charge on the geometry of space-time of such black holes are studied. It is shown that in most cases the scalar curvature is divergent at the horizons. Another feature of the dilaton black hole is that there is a finite interval of values of electric charge for which no black hole can exist.Comment: 20 pages, LaTeX file + 1 figure, CALT-68-1885. (the postscript file is improved
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