987 resultados para central algorithm


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O artigo analisa alguns aspectos da percepção brasileira sobre o conflito regional imperante na América Central, entre 1979 e 1996. Na conclusão sugere-se que essa política fundamentou-se no que aqui se chama de a "tese brasileira" sobre a origem, a evolução e os possíveis mecanismos de resolução para o conflito regional.

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Coffee cultivation via central-pivot fertigation can lead to fertilizer losses by soil profile internal drainage when water application is excessive and soils have low water retention and cation adsorption capacities. This study analyses the deep water losses from the top 1 m sandy soil layer of east Bahia, Brazil, cultivated with coffee at a high technology level (central-pivot fertigation), using above normal N fertilizer rates. The deep drainage (Q) estimation is made through the application of a climatologic water balance (CWB) program having as input direct measures of irrigation and rainfall, climatological data from weather stations, and measured soil water retention characteristics. The aim of the study is to contribute to the understanding of the hydric regime of coffee crops managed by central-pivot irrigation, analyzing three scenarios (Sc): i) rainfall only, ii) rainfall and irrigation full year, and iii) rainfall and irrigation dry season only. Annual Q values for the 2008/2009 agricultural year were: Sc i = 811.5 mm; Sc ii = 1010.5 mm; and Sc iii = 873.1 mm, so that the irrigation interruption in the wet season reduced Q by 15.7%, without the appearance of water deficit periods. Results show that the use of the CWB program is a convenient tool for the evaluation of Q under the cited conditions.

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Many organisations need to extract useful information from huge amounts of movement data. One example is found in maritime transportation, where the automated identification of a diverse range of traffic routes is a key management issue for improving the maintenance of ports and ocean routes, and accelerating ship traffic. This paper addresses, in a first stage, the research challenge of developing an approach for the automated identification of traffic routes based on clustering motion vectors rather than reconstructed trajectories. The immediate benefit of the proposed approach is to avoid the reconstruction of trajectories in terms of their geometric shape of the path, their position in space, their life span, and changes of speed, direction and other attributes over time. For clustering the moving objects, an adapted version of the Shared Nearest Neighbour algorithm is used. The motion vectors, with a position and a direction, are analysed in order to identify clusters of vectors that are moving towards the same direction. These clusters represent traffic routes and the preliminary results have shown to be promising for the automated identification of traffic routes with different shapes and densities, as well as for handling noise data.

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Nitrogen has a complex dynamics in the soil-plant-atmosphere system. N fertilizers are subject to chemical and microbial transformations in soils that can result in significant losses. Considering the cost of fertilizers, the adoption of good management practices like fertigation could improve the N use efficiency by crops. Water balances (WB) were applied to evaluate fertilizer N leaching using 15N labeled urea in west Bahia, Brazil. Three scenarios (2008/2009) were established: i) rainfall + irrigation the full year, ii) rainfall only; and iii) rainfall + irrigation only in the dry season. The water excess was considered equal to the deep drainage for the very flat area (runoff = 0) with a water table located several meters below soil surface (capillary rise = 0). The control volume for water balance calculations was the 0 - 1 m soil layer, considering that it involves the active root system. The water drained below 1 m was used to estimate fertilizer N leaching losses. WB calculations used the mathematic model of Penman-Monteith for evapotranspiration, considering the crop coefficient equal to unity. The high N application rate associated to the high rainfall plus irrigation was found to be the main cause for leaching, which values were 14.7 and 104.5 kg ha-1 for the rates 400 and 800 kg ha-1 of N, corresponding to 3.7 and 13.1 % of the applied fertilizer, respectively.

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In the category of Hom-Leibniz algebras we introduce the notion of Hom-corepresentation as adequate coefficients to construct the chain complex from which we compute the Leibniz homology of Hom-Leibniz algebras. We study universal central extensions of Hom-Leibniz algebras and generalize some classical results, nevertheless it is necessary to introduce new notions of α-central extension, universal α-central extension and α-perfect Hom-Leibniz algebra due to the fact that the composition of two central extensions of Hom-Leibniz algebras is not central. We also provide the recognition criteria for these kind of universal central extensions. We prove that an α-perfect Hom-Lie algebra admits a universal α-central extension in the categories of Hom-Lie and Hom-Leibniz algebras and we obtain the relationships between both of them. In case α = Id we recover the corresponding results on universal central extensions of Leibniz algebras.

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Light and soil water availability may limit carbon uptake of trees in tropical rainforests. The objective of this work was to determine how photosynthetic traits of juvenile trees respond to variations in rainfall seasonality, leaf nutrient content, and opening of the forest canopy. The correlation between leaf nutrient content and annual growth rate of saplings was also assessed. In a terra firme rainforest of the central Amazon, leaf nutrient content and gas exchange parameters were measured in five sapling tree species in the dry and rainy season of 2008. Sapling growth was measured in 2008 and 2009. Rainfall seasonality led to variations in soil water content, but it did not affect leaf gas exchange parameters. Subtle changes in the canopy opening affected CO2 saturated photosynthesis (A pot, p = 0.04). Although A pot was affected by leaf nutrient content (as follows: P > Mg > Ca > N > K), the relative growth rate of saplings correlated solely with leaf P content (r = 0.52, p = 0.003). At present, reduction in soil water content during the dry season does not seem to be strong enough to cause any effect on photosynthesis of saplings in central Amazonia. This study shows that leaf P content is positively correlated with sapling growth in the central Amazon. Therefore, the positive effect of atmospheric CO2 fertilization on long-term tree growth will depend on the ability of trees to absorb additional amount of P

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Quantitative analysis of cine cardiac magnetic resonance (CMR) images for the assessment of global left ventricular morphology and function remains a routine task in clinical cardiology practice. To date, this process requires user interaction and therefore prolongs the examination (i.e. cost) and introduces observer variability. In this study, we sought to validate the feasibility, accuracy, and time efficiency of a novel framework for automatic quantification of left ventricular global function in a clinical setting.

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Ultrapassado o período-pós revolucionário, ao longo das últimas décadas, as tendências de reforma administrativa em Portugal acompanharam aquilo que se passava no resto da Europa. Independentemente das idiossincrasias e das incoerências observadas, ao longo dos últimos 20 anos, o processo reformista foi marcado pela introdução das privatizações, da empresarialização da lógica administrativa, das tentativas de desburocratização e transparência na relação entre a administração e os cidadãos, da convergência de regimes laborais e da restruturação da Administração Pública Central. A partir de 2011, na sequência da assinatura do Memorando de Entendimento entre o governo português e a troika, a reforma restringiu-se essencialmente à aplicação de medidas avulsas que visaram sobretudo a redução dos custos da despesa pública. Não existindo para já referências teóricas científicas analíticas sobre a matéria tratada, o artigo apresenta uma abordagem descritiva e exploratória.

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El debate sobre la descentralización en Chile ha tomado un nuevo impulso de demandas a través de diversas acciones colectivas regionalistas desarrolladas desde el año 2011, las que han establecido un "nuevo ciclo" marcado por redefiniciones de las relaciones entre Estado y sociedad. Este nuevo periodo se ha caracterizado por un fuerte debate político, el que ha enfrentado a distintas posiciones e intereses en torno a cómo lograr una descentralización que permita un doble virtuosismo: desarrollar grados crecientes de autonomía evitando el caudillismo y la captura de los entes subnacionales por grupos y mafias locales, a la vez que generar un proceso descentralizador que evite la cooptación y control desde el poder central. Problematizando en torno a este último punto, el presente artículo es una investigación descriptiva-exploratoria, con énfasis en lo teórico, que busca identificar dimensiones de éxito de una descentralización no cooptativa, que sirvan como insumo al proceso chileno. Para ello se concluye que los tres pilares fundamentales para alcanzar una descentralización autónoma sin cooptación del poder central son el fortalecimiento y autonomía financiera, la participación y democratización territorial y un proceso de institucionalización.

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Abstract: In the last few decades, Central American countries are making a significant effort in order to modernize their governments' legislation both on financial management and systems of financial information. In this sense, these countries aim to enhance the quality of public financial information in order to improve decision-making processes, decrease the level of corruption, and keep citizens informed. In this context, the purpose of this paper is twofold. Firstly, to assess the degree of similarity of the financial information that is being developed by Central American governments with regard to the recommendations set up by Ipsas, and secondly, to analyse the efforts and the strategies that those countries are carrying out in the process of implementing those standards. To determine the differences in the information containing the annual financial statements issued by national public authorities and the recommendations set up by Ipsas we conducted a deductive content analysis. In view of the results we can say that the quality of annual financial statements presented by the countries in Central America, in comparison to the recommendations by the Ipsas concerning Ifac information, is not enough. Hence, in order to operate significant changes, it is still necessary to create new strategies for the implementation of the Ipsas.

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Este artigo apresenta subsídios arqueológicos para o debate - revisitado por Franciso Noelli, Eduardo Viveiros de Castro e Greg Urban nas páginas da Revista de Antropologia - sobre a suposta origem das línguas do tronco Tupí na Amazônia central. Apresentamos aqui os resultados preliminares de nossas pesquisas arqueológicas na área de confluência dos rios Negro e Solimões que levantam restrições às premissas arqueológicas desse modelo, primeiramente apresentadas por Donald Lathrap em 1970.

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Neste artigo, o valor panará de disposição e sociabilidade (suakiin) é contrastado com seu oposto, falta de disposição e retraimento social (suangka), para mostrar como a vida codiana panará é constituída. Caracterizadas como condições físicas, sociais e morais, a disponibilidade intersubjetiva ou a falta de vigor são centrais à criação da socialidade cotidiana entre os Panará. O papel dessas relações afetivas é, então, analisado com base na criação dos filhos e no cultivo de roças, processos que, em determinados aspectos, podem ser tidos como relacionados entre si. Em particular, demonstra-se que certas práticas pré e pós-natais têm correspondência com práticas que cercam o plantio, o cultivo e a colheita do amendoim.