4,988 research outputs found

    Quanto vale o Pantanal? A valoração ambiental aplicada ao bioma Pantanal.

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    As informações contidas nesta publicação buscam assegurar a efetividade de políticas que garantam a sustentabilidade do bioma e ao mesmo tempo assegurem que a tomada de decisões em projetos para seu desenvolvimento, sejam coerentes e racionais. Neste sentido, é necessário que os múltiplos usos e valores dessas áreas úmidas sejam reconhecidos e considerados, mais particularmente o seu valor econômico, já que as decisões de planejamento de uso da terra tradicionalmente se baseiam em considerações econômicas. Os autores mostram que as estimativas desses valores devem estar baseadas em técnicas adequadas, pois os métodos tradicionais não conseguem determinar os benefícios de muitas funções ambientais ou os custos de sua perda. Também reportam que por meio de tais técnicas, conhecidas como métodos de valoração ambiental, é possível determinar o valor monetário dos bens e serviços ambientais em relação a outros bens e serviços da economia, e dessa forma, refletir seus valores sociais e não meramente seus valores de mercado. Este trabalho explica de forma simples os fundamentos da valoração econômica ambiental e seu papel na tomada de decisões sobre os usos do Pantanal e leva o leitor a pensar na valoração econômica de ecossistemas como mais um elemento a ser considerado quando se tomam decisões de uso de áreas úmidas.bitstream/CPAP-2010/57310/1/DOC105.pd

    Hubbard-model description of the high-energy spin-spectral-weight distribution in La(2)CuO(4)

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    The spectral-weight distribution in recent neutron scattering experiments on the parent compound La2_2CuO4_4 (LCO), which are limited in energy range to about 450\,meV, is studied in the framework of the Hubbard model on the square lattice with effective nearest-neighbor transfer integral tt and on-site repulsion UU. Our study combines a number of numerical and theoretical approaches, including, in addition to standard treatments, density matrix renormalization group calculations for Hubbard cylinders and a suitable spinon approach for the spin excitations. Our results confirm that the U/8tU/8t magnitude suitable to LCO corresponds to intermediate UU values smaller than the bandwidth 8t8t, which we estimate to be 8t2.368t \approx 2.36 eV for U/8t0.76U/8t\approx 0.76. This confirms the unsuitability of the conventional linear spin-wave theory. Our theoretical studies provide evidence for the occurrence of ground-state d-wave spinon pairing in the half-filled Hubbard model on the square lattice. This pairing applies only to the rotated-electron spin degrees of freedom, but it could play a role in a possible electron d-wave pairing formation upon hole doping. We find that the higher-energy spin spectral weight extends to about 566 meV and is located at and near the momentum [π,π][\pi,\pi]. The continuum weight energy-integrated intensity vanishes or is extremely small at momentum [π,0][\pi,0]. This behavior of this intensity is consistent with that of the spin waves observed in recent high-energy neutron scattering experiments, which are damped at the momentum [π,0][\pi,0]. We suggest that future LCO neutron scattering experiments scan the energies between 450 meV and 566 meV and momenta around [π,π][\pi,\pi].Comment: 23 pages, 5 figure

    A Suspension-Trace Semantics for CSP

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    CSP is well established as a process algebra for refinement. Most refinement relations for CSP do not differentiate between inputs and outputs, and so are unsuitable for testing. This paper provides CSP with a denotational semantics based on suspension traces; it gives the traditional CSP operators a novel view, catering for the differences between inputs and outputs. We identify healthiness conditions for the suspension-Traces model and include a treatment of termination not contemplated in the context of input-output labelled transition systems. Using our suspension-Traces semantics, we provide for CSP a characterisation of the conformance relation ioco, which is widely used in testing. Finally, we propose a strategy to mechanise the verification of conformance according to ioco and suspension-Trace refinement using CSP tools. This work provides the basis for a theory of testing for CSP with inputs and outputs, and opens up the possibility of studying algebraic laws and compositional reasoning techniques based on ioco. Ultimately, it contributes to making CSP models useful for both design and testing of systems.We thank Bill Roscoe for useful discussions. The work was carried out with the support of EPSRC hiJaC project, the CNPq (Brazil), INES, and the grants FACEPE 573964/2008-4, APQ-1037-1.03/08, CNPq 573964/2008-4, 476821/2011-8 and 249710/2013-7

    Rentabilidade da pecuária tradicional do Pantanal para fazendas com e sem pastagens cultivadas.

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    Dados primários sobre a pecuária pantaneira foram obtidos de questionários enviados via correio a pecuaristas do Pantanal, seguindo convenções metodológicas. O questionário foi elaborado de modo a obter informações que permitissem descrever e caracterizar de forma geral a pecuária pantaneira, identificar diferenças entre sistemas de produção e, particularmente, para permitir investigar a rentabilidade das fazendas considerando dois níveis tecnológicos: com e sem pastagens cultivadas. Primary data on Pantanal livestock were obtained from questionnaires sent by mail to ranchers in the Pantanal. The questionnaire was prepared in order to obtain information enabling to describe and characterize in a general way the Pantanal livestock, identifying differences between production systems and particularly to allow to investigate the profitability of farms considering two technological levels: with and without cultivated pastures

    Basketball game-related statistics that discriminate between teams season-long success

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    The aim of the present study was to identify the game-related statistics that discriminate between season-long successful and unsuccessful basketball teams participating in the Spanish Basketball League (LEB1). The sample included all 145 average records per season from the 870 games played between the 2000-2001 and the 2005-2006 regular seasons. The following game-related statistics were gathered from the official box scores of the Spanish Basketball Federation: 2- and 3-point field-goal attempts (both successful and unsuccessful), free-throws (both successful and unsuccessful), defensive and offensive rebounds, assists, steals, turnovers, blocks (both made and received), and fouls (both committed and received). To control for season variability, all results were normalized to minutes played each season and then converted to z-scores. The results allowed discrimination between best and worst teams' performances through the following game-related statistics: assists (SC=0.47), steals (SC=0.34), and blocks (SC=0.30). The function obtained correctly classified 82.4% of the cases. In conclusion, season-long performance may be supported by players' and teams' passing skills and defensive preparation
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