38,239 research outputs found

    District/State economic conditions : District economic overview

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    Economic indicators ; Federal Reserve District, 5th

    Cosmological perturbation theory in 1+1 dimensions

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    Many recent studies have highlighted certain failures of the standard Eulerian-space cosmological perturbation theory (SPT). Its problems include (1) not capturing large-scale bulk flows [leading to an O(1) error in the 1-loop SPT prediction for the baryon acoustic peak in the correlation function], (2) assuming that the Universe behaves as a pressureless, inviscid fluid, and (3) treating fluctuations on scales that are non-perturbative as if they were. Recent studies have highlighted the successes of perturbation theory in Lagrangian space or theories that solve equations for the effective dynamics of smoothed fields. Both approaches mitigate some or all of the aforementioned issues with SPT. We discuss these physical developments by specializing to the simplified 1D case of gravitationally interacting sheets, which allows us to substantially reduces the analytic overhead and still (as we show) maintain many of the same behaviors as in 3D. In 1D, linear-order Lagrangian perturbation theory ("the Zeldovich approximation") is exact up to shell crossing, and we prove that n^{th}-order Eulerian perturbation theory converges to the Zeldovich approximation as n goes to infinity. In no 1D cosmology that we consider (including a CDM-like case and power-law models) do these theories describe accurately the matter power spectrum on any mildly nonlinear scale. We find that theories based on effective equations are much more successful at describing the dynamics. Finally, we discuss many topics that have recently appeared in the perturbation theory literature such as beat coupling, the shift and smearing of the baryon acoustic oscillation feature, and the advantages of Fourier versus configuration space. Our simplified 1D case serves as an intuitive review of these perturbation theory results.Comment: 28 pages + appendices; 10 figures; matches version accepted to JCA

    District/State economic conditions : District economic overview

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    Economic indicators ; Federal Reserve District, 5th

    Recircumscription of the Nepenthes alata group (Caryophyllales: Nepenthaceae) in the Philippines : with four new species

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    An overview of Nepenthes in the Philippines is presented. Four new species, Nepenthes extincta sp. nov., N. kitanglad sp. nov., N. kurata sp. nov. and N. leyte sp. nov. are described and illustrated from the Philippines and placed in the Nepenthes alata group. An updated circumscription and key to the species of the group is provided. Delimitation and comparison with the Regiae group is given. All four of the newly described species are assessed as threatened using the International Union for the Conservation of Nature 2012 standard, and one, N. extincta sp. nov. is considered likely to be already extinct due to open-cast mining. Logging and conversion of forest habitat are thought to be the main threats to the other three species

    Terrorizing Advocacy and the First Amendment: Free Expression and the Fallacy of Mutual Exclusivity

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    Traditional free speech doctrine is inadequate to account for modern terrorist speech. Unprotected threats and substantially protected lawful advocacy are not mutually exclusive. This Article proposes recognizing a new hybrid category of speech called “terrorizing advocacy.” This is a type of traditionally protected public advocacy of unlawful conduct that simultaneously exhibits the unprotected pathologies of a true threat. This Article explains why this new category confounds existing First Amendment doctrine and details a proposed model for how the doctrine should be reshaped

    Regulation and Barriers to Trade in Telecommunications Services in the European Union

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    Recent advances in telecommunications, particularly using fibre technologies, permit many services based on data-processing to be performed anywhere in the world. They thus become tradable and subject to the laws of comparative advantage. A good example is data-processing within large multi-national corporations, the integrated performance of which can reduce cost and add considerable value. Whereas a single market for the provision of such services has arisen in the US, the equivalent single market in the European Union is impeded by absent or imperfect regulation conducted at the national level, which fails to create a level playing field between the country’s former telecommunications monopolist and foreign competitors and prevents the emergence of trade in services, at considerable potential cost to firms operating in the EU. The paper discusses how this problem can be resolved by improved regulatory practice and evaluates the prospects for institutional change, in the form of more centralised scrutiny of regulatory remedies, which would make this more achievable.
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