4,558 research outputs found
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The significance of culture, tourism and leisure services in social and economic development in the NE of England
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Challenges to democratic legitimacy, scrutiny, accountability in the UK national and local state
This article suggests that at national and local levels, the British state is seemingly incapable of solving multi-faceted and intractable social, economic and environmental problems alone. It is argued that new national and local governance arrangements, based on new ideas, different ways of working, and approaches to problem solving have brought into a sharper focus on the issues of democratic legitimacy, scrutiny and accountability. All three complex and ambiguous concepts have long been a concern in public administration. This article draws from existing conceptual frameworks to show that traditional forms of legitimacy, scrutiny and accountability are now under threat. It examines the merits of the new forms, with some recommendations for the future
A classification of scalar field potentials with cosmological scaling solutions
An attractive method of obtaining an effective cosmological constant at the
present epoch is through the potential energy of a scalar field. Considering
models with a perfect fluid and a scalar field, we classify all potentials for
which the scalar field energy density scales as a power-law of the scale factor
when the perfect fluid density dominates. There are three possibilities. The
first two are well known; the much-investigated exponential potentials have the
scalar field mimicking the evolution of the perfect fluid, while for negative
power-laws, introduced by Ratra and Peebles, the scalar field density grows
relative to that of the fluid. The third possibility is a new one, where the
potential is a positive power-law and the scalar field energy density decays
relative to the perfect fluid. We provide a complete analysis of exact
solutions and their stability properties, and investigate a range of possible
cosmological applications.Comment: 8 pages RevTeX file with four figures incorporated (uses RevTeX and
epsf
The lepton asymmetry: the last chance for a critical-density cosmology?
We use a wide range of observations to constrain cosmological models possessing a significant asymmetry in the lepton sector, which offer perhaps the best chance of reconciling a critical-density Universe with current observations. The simplest case, with massless neutrinos, fails to fit many experimental data and does not lead to an acceptable model. If the neutrinos have mass of order one electron-volt (which is favoured by some neutrino observations), then models can be implemented which prove a good fit to microwave anisotropies and large-scale structure data. However, taking into account the latest microwave anisotropy results, especially those from Boomerang, we show that the model can no longer accommodate the observed baryon fraction in clusters. Together with the observed acceleration of the present Universe, this puts considerable pressure on such critical-density models
Can Inflation be Falsified?
Despite its central role in modern cosmology, doubts are often expressed as
to whether cosmological inflation is really a falsifiable theory. We
distinguish two facets of inflation, one as a theory of initial conditions for
the hot big bang and the other as a model for the origin of structure in the
Universe. We argue that the latter can readily be excluded by observations, and
that there are also a number of ways in which the former can find itself in
conflict with observational data. Both aspects of the theory are indeed
falsifiable.Comment: 7 pages LaTeX file with two figures incorporated by epsf. Fifth Prize
in Gravity Research Foundation Essay Competition. To appear, General
Relativity and Gravitatio
Cosmological parameter estimation and the spectral index from inflation
Accurate estimation of cosmological parameters from microwave background
anisotropies requires high-accuracy understanding of the cosmological model.
Normally, a power-law spectrum of density perturbations is assumed, in which
case the spectral index can be measured to around using
microwave anisotropy satellites such as MAP and Planck. However, inflationary
models generically predict that the spectral index of the density
perturbation spectrum will be scale-dependent. We carry out a detailed
investigation of the measurability of this scale dependence by Planck,
including the influence of polarization on the parameter estimation. We also
estimate the increase in the uncertainty in all other parameters if the scale
dependence has to be included. This increase applies even if the scale
dependence is too small to be measured unless it is assumed absent, but is
shown to be a small effect. We study the implications for inflation models,
beginning with a brief examination of the generic slow-roll inflation
situation, and then move to a detailed examination of a recently-devised hybrid
inflation model for which the scale dependence of may be observable.Comment: 6 pages LaTeX file with one figure incorporated (uses mn.sty and
epsf). Important modifications to result
Generalized Slow Roll Conditions and the Possibility of Intermediate Scale Inflation in Scalar-Tensor Theory
Generalized slow roll conditions and parameters are obtained for a general
form of scalar-tensor theory (with no external sources), having arbitrary
functions describing a nonminimal gravitational coupling F(\phi), a Kahler-like
kinetic function k(\phi), and a scalar potential V(\phi). These results are
then used to analyze a simple toy model example of chaotic inflation with a
single scalar field \phi and a standard Higgs potential and a simple
gravitational coupling function. In this type of model inflation can occur with
inflaton field values at an intermediate scale of roughly 10^{11} GeV when the
particle physics symmetry breaking scale is approximately 1 TeV, provided that
the theory is realized within the Jordan frame. If the theory is realized in
the Einstein frame, however, the intermediate scale inflation does not occur.Comment: 14 pages, no figs. Accepted to Classical and Quantum Gravit
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Strategic leisure services as 'integrator and broker': best value as a stimulus to local regeneration?
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