6,785 research outputs found

    Characterizing neuromorphologic alterations with additive shape functionals

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    The complexity of a neuronal cell shape is known to be related to its function. Specifically, among other indicators, a decreased complexity in the dendritic trees of cortical pyramidal neurons has been associated with mental retardation. In this paper we develop a procedure to address the characterization of morphological changes induced in cultured neurons by over-expressing a gene involved in mental retardation. Measures associated with the multiscale connectivity, an additive image functional, are found to give a reasonable separation criterion between two categories of cells. One category consists of a control group and two transfected groups of neurons, and the other, a class of cat ganglionary cells. The reported framework also identified a trend towards lower complexity in one of the transfected groups. Such results establish the suggested measures as an effective descriptors of cell shape

    Opinion and community formation in coevolving networks

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    In human societies opinion formation is mediated by social interactions, consequently taking place on a network of relationships and at the same time influencing the structure of the network and its evolution. To investigate this coevolution of opinions and social interaction structure we develop a dynamic agent-based network model, by taking into account short range interactions like discussions between individuals, long range interactions like a sense for overall mood modulated by the attitudes of individuals, and external field corresponding to outside influence. Moreover, individual biases can be naturally taken into account. In addition the model includes the opinion dependent link-rewiring scheme to describe network topology coevolution with a slower time scale than that of the opinion formation. With this model comprehensive numerical simulations and mean field calculations have been carried out and they show the importance of the separation between fast and slow time scales resulting in the network to organize as well-connected small communities of agents with the same opinion.Comment: 10 pages, 5 figures. New inset for Fig. 1 and references added. Submitted to Physical Review

    Status of the HIE-ISOLDE project at CERN

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    The HIE-ISOLDE project represents a major upgrade of the ISOLDE nuclear facility with a mandate to significantly improve the quality and increase the intensity and energy of radioactive nuclear beams produced at CERN. The project will expand the experimental nuclear physics programme at ISOLDE by focusing on an upgrade of the existing Radioactive ion beam EXperiment (REX) linac with a 40 MV superconducting linac comprising thirty-two niobium-on-copper sputter-coated quarter-wave resonators housed in six cryomodules. The new linac will raise the energy of post-accelerated beams from 3 MeV/u to over 10 MeV/u. The upgrade will be staged to first deliver beam energies of 5.5 MeV/u using two high-β\beta cryomodules placed downstream of REX, before the energy variable section of the existing linac is replaced with two low-β\beta cryomodules and two additional high-β\beta cryomodules are installed to attain over 10 MeV/u with full energy variability above 0.45 MeV/u. An overview of the project including a status summary of the different R&D activities and the schedule will outlined.Comment: 7 pages, 12 figures, submitted to the Heavy Ion Accelerator Technology conference (HIAT) 2012, in Chicag

    Hyperfine magnetic field in ferromagnetic graphite

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    Information on atomic-scale features is required for a better understanding of the mechanisms leading to magnetism in non-metallic, carbon-based materials. This work reports a direct evaluation of the hyperfine magnetic field produced at 13C nuclei in ferromagnetic graphite by nuclear magnetic resonance (NMR). The experimental investigation was made possible by the results of first-principles calculations carried out in model systems, including graphene sheets with atomic vacancies and graphite nanoribbons with edge sites partially passivated by oxygen. A similar range of maximum hyperfine magnetic field values (18-21T) was found for all systems, setting the frequency span to be investigated in the NMR experiments; accordingly, a significant 13C NMR signal was detected close to this range without any external applied magnetic field in ferromagnetic graphite

    Avaliação de classificadores automáticos no mapeamento de áreas cafeeiras da Região de Guaxupé, Minas Gerais.

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    O mapeamento da ocupação da terra constitui uma das mais importantes atividades de geração de dados para gerenciamento e monitoramento de ambientes agrícolas. Pretendeu-se neste trabalho avaliar a exatidão da interpretação visual de uma imagem SPOT 5 no mapeamento do café na região de Guaxupé, tendo como referência dados obtidos em campo, bem como comparar o desempenho de técnicas de mapeamento automático da mesma área em comparação com a interpretação visual,visando a avaliação da viabilidade de aplicação destas técnicas para agilizar o mapeamento do parque cafeeiro na região.Foram trabalhadas imagens SPOT 5 com resolução espacial de 10 metros e de 2,5 metros. A cena foi submetida ao processamento por diferentes métodos de classificação automática para a imagem com resolução de 10 metros e por interpretação visual para a imagem com resolução de 2,5 metros. Dados obtidos em campo foram tomados como referência para obtenção de índices de exatidão do mapeamento. Foram estratificadas as classes café, mata e outros usos, sendo esta última oriunda do agrupamento dos demais tipos de vegetação como culturas anuais, pastagens, solo exposto, áreas urbanas, etc. Os índices utilizados foram calculados de maneira a permitir a avaliação da exatidão global da classificação e também individualmente para a classe café

    Volatilização de amônia de fontes nitrogenadas em feijoeiro irrigado no sistema plantio direto.

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    O objetivo deste estudo foi avaliar as perdas de N por volatilização de NH3, em diferentes fontes de nitrogênio aplicadas no feijoeiro comum irrigado, cultivado em Latossolo de Cerrado sobre palhada de braquiária em sistema plantio direto.Conpeex 2010

    Volatilização de amônia de adubos nitrogenados aplicados no feijoeiro irrigado cultivado no sistema plantio direto.

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    Este trabalho teve como objetivo avaliar as perdas de N por volatilização de NH3, com a aplicação de diferentes fontes nitrogenadas no feijoeiro cultivado em sistema plantio direto no inverno

    Variáveis e modelos para estimativa da produtividade do cafeeiro a partir de índices de vegetação derivados de imagens Landsat.

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    Abstract. Coffee fields present a specific pattern of productivity resulting in high and low production in alternated years. Branches grown the first phenological year will produce coffee beans the second phenological year. In high-production years a plant works mostly to grain-filling to the detriment of new branches which will be responsible for production the following year. In low-production years the plant works rather to grow new branches which will produce beans the subsequent year. This feature can be related to the foliar biomass, which can be estimated through remote sensing derived vegetation indices. Several studies report this feature must be incorporated in modeling coffee yield coupled with agrometeorogical models. In this paper we derived Landsat vegetation indices related to coffee plots in order to obtain relationships to yield of the same coffee plots. Biophisical variables and yield data were colected in interviews with farmers from four locations in the whole largest Brazilian coffee-exporting province. Vegetation indices and biophysical variables were selected through stepwise regression in order to obtain the best regression models to estimate coffee yield. Outcomes showed that general models and specific models obtained for Mundo Novo variety presented Pearson's correlation coeficients (r) from 0,64 to 0,71 while models for Catuaí variety showed better results (r = 0,85). Although coffee yield cannot be estimated exclusively from these models, they can be usefull coupled with agrometeorogical models for estimating coffee yield

    Development of zein-based edible coating containing essential oil aiming extending papaya (Carica papaya L.) shelf life.

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    Zeins are hydrophobic proteins that can be extracted from maize grains or from corn gluten meal (CGM), which is a by-product of ethanol and starch production
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