3,486 research outputs found

    Sustainability Assessment of indicators for integrated water resources management

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    The scientific community strongly recommends the adoption of indicators for the evaluation and monitoring of progress towards sustainable development. Furthermore, international organizations consider that indicators are powerful decision-making tools. Nevertheless, the quality and reliability of the indicators depends on the application of adequate and appropriate criteria to assess them. The general objective of this study was to evaluate how indicators related to water use and management perform against a set of sustainability criteria. Our research identified 170 indicators related to water use and management. These indicators were assessed by an international panel of experts that evaluated whether they fulfil the four sustainability criteria: social, economic, environmental, and institutional. We employed an evaluation matrix that classified all indicators according to the DPSIR (Driving Forces, Pressures, States, Impacts and Responses) framework. A pilot study served to test and approve the research methodology before carrying out the full implementation. The findings of the study show that 24 indicators comply with the majority of the sustainability criteria; 59 indicators are bi-dimensional (meaning that they comply with two sustainability criteria); 86 are one-dimensional indicators (fulfilling just one of the four sustainability criteria) and one indicator do not fulfil any of the sustainability criteria.Postprint (author's final draft

    Non-singular inflation with vacuum decay

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    On the basis of a semi-classical analysis of vacuum energy in an expanding spacetime, we describe a non-singular cosmological model in which the vacuum density decays with time, with a concomitant production of matter. During an infinitely long period we have an empty, inflationary universe, with H \approx 1. This primordial era ends in a fast phase transition, during which H and \Lambda decrease to nearly zero in a few Planck times, with release of a huge amount of radiation. The late-time scenario is similar to the standard model, with the radiation phase followed by a long dust era, which tends asymptotically to a de Sitter universe, with vacuum dominating again. An analysis of the redshift-distance relation for supernovas Ia leads to cosmological parameters in agreement with other current estimations.Comment: Work presented at IRGAC 2006, Barcelona, July 11-15 2006. To appear in a special issue of Journal of Physics

    Embrapa Recursos Genéticos e Biotecnologia e sua atuação no programa de pó-graduação em Biologia Molecular da Universidade de Brasília.

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    Segmentação de sistemas de produção de leite como instrumento de apoio a decisão e gestão da atividade leiteira.

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    Qualquer sistema de produção pode ser considerado como um caixa preta, em que os insumos e produtos são conhecidos e mensuráveis, embora o processo de transformação dos insumos em produtos seja desconhecidos. Neles, a correta colocação de recursos, muitas vezes, fica prejudicada pela impossibilidade de se conhecer a exata dimensão ou quantidade de recursos utilizados em cada uma das fases do processo produtivo. Uma das formas de melhorar o entendimento de processos produtivos complexos é segmentar o sistema em partes menores, ou seja em abrir alguns dos compartimentos ue compõem a caixa preta, em que cada um representa uma parte do processo de transformacao. O que se propoe neste estudo e segmentar o sistema global de producao de leite em quatro setores quais sejam: a) producao de leite; b) producao de novilhas para reposição do plantel de vacas; c)producao de alimentos volumosos; e d)maquinas e implementos. Acredita-se que a analise segmentada da atividade leiteira traga grandes vantagens em vista da organização e administracao da producao

    O Brasil no cenário mundial de lácteos.

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    Spontaneous emergence of spatial patterns ina a predator-prey model

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    We present studies for an individual based model of three interacting populations whose individuals are mobile in a 2D-lattice. We focus on the pattern formation in the spatial distributions of the populations. Also relevant is the relationship between pattern formation and features of the populations' time series. Our model displays travelling waves solutions, clustering and uniform distributions, all related to the parameters values. We also observed that the regeneration rate, the parameter associated to the primary level of trophic chain, the plants, regulated the presence of predators, as well as the type of spatial configuration.Comment: 17 pages and 15 figure

    Bandlimited approximations to the truncated Gaussian and applications

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    In this paper we extend the theory of optimal approximations of functions f:RRf: \R \to \R in the L1(R)L^1(\R)-metric by entire functions of prescribed exponential type (bandlimited functions). We solve this problem for the truncated and the odd Gaussians using explicit integral representations and fine properties of truncated theta functions obtained via the maximum principle for the heat operator. As applications, we recover most of the previously known examples in the literature and further extend the class of truncated and odd functions for which this extremal problem can be solved, by integration on the free parameter and the use of tempered distribution arguments. This is the counterpart of the work \cite{CLV}, where the case of even functions is treated.Comment: to appear in Const. Appro
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