846 resultados para information theory and computation
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It is possible to show that there are three independent families of models describing a massive spin-2 particle via a rank-2 tensor. One of them contains the massive Fierz-Pauli model, the only case described by a symmetric tensor. The three families have different local symmetries in the massless limit and can not be interconnected by any local field redefinition. We show here, however, that they can be related with the help of a decoupled and nondynamic (spectator) field. The spectator field may be either an antisymmetric tensor B μν=-Bνμ, a vector Aμ or a scalar field φ, corresponding to each of the three families. The addition of the extra field allows us to formulate master actions which interpolate between the symmetric Fierz-Pauli theory and the other models. We argue that massive gravity models based on the Fierz-Pauli theory are not expected to be equivalent to possible local self-interacting theories built up on top of the two new families of massive spin-2 models. The approach used here may be useful to investigate dual (nonsymmetric) formulations of higher-spin particles. © 2013 American Physical Society.
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Includes bibliography
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Includes bibliography
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Includes bibliography
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Principle 10 of the Rio Declaration on Environment and Development, 1992
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Incluye Bibliografía
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Contiene antecedentes y lineamientos para formular e impulsar un programa regional de cooperacion entre redes y sistemas nacionales de informacion existentes en America Latina y el Caribe.
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This article contains a theoretical and policy analysis of the financial constraints on economic development in developing countries. Following a Keynesian interpretation, it concludes that financial policies are needed to relieve these constraints, given the natural tendency of financial systems to operate in ways that are dysfunctional to economic development. It then proposes three lines of policy that take account of the special characteristics of developing countries: resource allocation policies targeted at segments of strategic importance for economic and financial development; policies to control financial and external fragility; and compensatory policies of a more interventionist cast, in particular directed credit programmes for both public- and private-sector lending to complement resource allocation policies, and countercyclical regulatory barriers so that fragility can be better controlled.
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This technical document has been prepared by the Economic Commission for Latin America and the Caribbean (ECLAC) as requested by the countries signatory to the Declaration on the application of Principle 10 of the Rio Declaration on Environment and Development in Latin America and the Caribbean in the Santiago Decision adopted at the fourth meeting of the focal points appointed by the Governments of the signatory countries of the Declaration held in Santiago, Chile, from 4 to 6 November 2014.