1,193 research outputs found

    An independent estimate of the triple-Pomeron coupling

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    The value of the important triple-Pomeron coupling is estimated by an unorthodox procedure using the known diffractive parton distribution functions. The result is g_{3P}\simeq 0.2g_N, where g_N is the Pomeron-nucleon coupling. This is in excellent agreement with an independent determination, g_{3P}\simeq 0.2g_N, previously obtained by analysing the available data in the triple-Regge region with absorptive effects taken into account.Comment: 7 pages, 5 figure

    Ouro secundårio em couraças lateríticas na região de Cuiabå - MT

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    FORMAS DE HUMUS EM ECOSSISTEMAS DE FLORESTA COSTEIRA INTERTROPICAL. 1- A MATA ATLANTICA DE TABULEIROS

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    The Mata Atlantica ecosystems, located in the north part of Espirito Santo (Linhares) has two humus foons according to the forest type: Mata Alta Forest and Mussununga Forest. In the first case, humus is a mull-like fonn, and in the second, a moder-like humus is present. In the moder humus, 22t/ha corresponding to holorganic horizons- are superposed ou the A horizon, with 500kg/ha of organic nitrogen, while in the mull, this quantity reaches 6t/ha, with 100kg/ha of organic nitrogen. Below-ground pools -A horizon at 0-10cm depth- are similar in the two decomposition systems (10t/ha of organic carbon and700kg/ha of total nitrogen). A marked organic matter accumulation in Mussunnnga forest is essentially linked to the parental soil substrata with a limited clay fraction and very poor nutrieut content. Despite the factors detennining the humus fonns, which are simihlr to temperate forests, Mata AtlĂąntica humus are differentiated by faster recycling of nutrieuts and a high organic-maner turnover.O ecossistema de Mata Atlantica localizado no norte do EspĂ­rito Santo (Linhares), apresenta duas fomas de hĂșmus, de acordo com o tipo florestal: Mata Alta e Mata Mussununga. No primeiro caso, observa-se um hĂșmus do tipo mull, enquanto a segunda fitofisionomia apresenta um humus do tipo moder. Nesta forma de humus, encontramos no horizonte holorgĂąnico 22t/ha de matĂ©ria orgĂąnica superficial e 500kg/ha de nitrogĂȘnio orgĂąnico, enquanto no mull, estes valores alcançam 6t/ha de matĂ©ria orgĂąnica superficial e 100kg/ha de nitrogĂȘnio orgĂąnico. Com relação ao horizonte A subjacente (0-10cm), as duas ĂĄreas sĂŁo similares nos seus conteĂșdos de matĂ©ria orgĂąnica nitrogĂȘnio (10t/ha de carbono orgĂąnico e 700kg/ha de nitrogĂȘnio total). Uma marcada acumulação superficial de matĂ©ria orgĂąnica na Mata de Mussununga estĂĄ intimamente relacionada Ă  composição do substrato parental, com uma limitada fração de argila e baixĂ­ssimo conteĂșdo de nutrientes. Apesar dos fatores determinantes das formas hĂșmicas serem semelhantes aos das florestas temperadas, os hĂșmus da Mata AtlĂąntica sĂŁo diferenciados pela rĂĄpida reciclagem de nutrientes e alto" turnover" da matĂ©ria orgĂąnica

    Bootstrapping a Portuguese WordNet from Galician, Spanish and English wordnets

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    Series: Lecture notes in computer science, ISSN 0302-9743, vol. 8854In this article we exploit the possibility on bootstrapping an European Portuguese WordNet from the English, Spanish and Galician wordnets using Probabilistic Translation Dictionaries automatically created from parallel corpora. The process generated a total of 56~770 synsets and 97~058 variants. An evaluation of the results using the Brazilian OpenWordNet-PT as a gold standard resulted on a precision varying from 53\% to 75\% percent, depending on the cut-line. The results were satisfying and comparable to similar experiments using the WN-Toolkit.PEst-OE/EEI/UI0752/2014, TIN2012-38584-C06-01, TIN2012-38584-C06-0

    User-friendly tail bounds for sums of random matrices

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    This paper presents new probability inequalities for sums of independent, random, self-adjoint matrices. These results place simple and easily verifiable hypotheses on the summands, and they deliver strong conclusions about the large-deviation behavior of the maximum eigenvalue of the sum. Tail bounds for the norm of a sum of random rectangular matrices follow as an immediate corollary. The proof techniques also yield some information about matrix-valued martingales. In other words, this paper provides noncommutative generalizations of the classical bounds associated with the names Azuma, Bennett, Bernstein, Chernoff, Hoeffding, and McDiarmid. The matrix inequalities promise the same diversity of application, ease of use, and strength of conclusion that have made the scalar inequalities so valuable.Comment: Current paper is the version of record. The material on Freedman's inequality has been moved to a separate note; other martingale bounds are described in Caltech ACM Report 2011-0

    Transforming data by calculation

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    Thispaperaddressesthefoundationsofdata-modeltransformation.A catalog of data mappings is presented which includes abstraction and representa- tion relations and associated constraints. These are justified in an algebraic style via the pointfree-transform, a technique whereby predicates are lifted to binary relation terms (of the algebra of programming) in a two-level style encompassing both data and operations. This approach to data calculation, which also includes transformation of recursive data models into “flat” database schemes, is offered as alternative to standard database design from abstract models. The calculus is also used to establish a link between the proposed transformational style and bidi- rectional lenses developed in the context of the classical view-update problem.Fundação para a CiĂȘncia e a Tecnologia (FCT
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