4,979 research outputs found

    Homogeneous metallicities and radial velocities for Galactic globular clusters. II. New CaT metallicities for 28 distant and reddened globular clusters

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    Although the globular clusters in the Milky Way have been studied for a long time, a significant fraction of them lack homogeneous metallicity and radial velocity measurements. In an earlier paper we presented the first part of a project to obtain metallicities and radial velocities of Galactic globular clusters from multiobject spectroscopy of their member stars using the ESO Very Large Telescope. In this paper we add metallicities and radial velocities for a new sample of 28 globular clusters, including in particular globular clusters in the MW halo and the Galactic bulge. Together with our previous results, this study brings the number of globular clusters with homogeneous measurements to 69\sim 69 \% of those listed in the W. Harris' catalogue. As in our previous work, we have used the CaII triplet lines to derive metallicities and radial velocities. For most of the clusters in this study, this is the first analysis based on spectroscopy of individual member stars. The metallicities derived from the CaII triplet are then compared to the results of our parallel study based on spectral fitting in the optical region and the implications for different calibrations of the CaII triplet line strengths are discussed. We also comment on some interesting clusters and investigate the presence of an abundance spread in the globular clusters here. A hint of a possible intrinsic spread is found for NGC 6256, which therefore appears to be a good candidate for further study.Comment: 13 pages, 9 figures, accepted for publication in Astronomy and Astrophysic

    Variedades tradicionais de feijão comum (Phaseolus vulgaris), com tipo de grão vermelho, resistentes à antracnose.

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    O objetivo do trabalho foi a determinação de fontes de resistência a seis patótipos de Colletotrichum lindemuthianum em variedades tradicionais de feijão comum (Phaseolus vulgaris) com tipo de grão vermelho. Foram avaliadas 50 variedades tradicionais para os patótipos 65, 73, 77 81 91 e 1609 de Colletotrichum lindemuthianum

    Modelling complex cracks with finite elements: a kinematically enriched constitutive model

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    A continuum constitutive framework with embedded cohesive interface model is presented to describe the failure of quasi-brittle materials. Both cohesive behaviour for cracking inside the fracture process zone and elastic bulk behaviour are treated at integration points making implementation straightforward. In this sense, the proposed approach is simpler than existing ones that focus on element enrichments, such as the extended finite element method, while share similarities with smeared crack models, and offers the capability to correctly model quasi-brittle failure in post-peak regime at constitutive level. In this work, the formulation is introduced, numerical algorithms described and static and dynamic fracture simulations with complex crack patterns are conducted to demonstrate the capability and advantage of the proposed approach.ARC DP140100945, ARC FT140100408, ARC DE 15010170

    Modelling complex cracks with finite elements: a kinematically enriched constitutive model

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    A continuum constitutive framework with embedded cohesive interface model is presented to describe the failure of quasi-brittle materials. Both cohesive behaviour for cracking inside the fracture process zone and elastic bulk behaviour are treated at integration points making implementation straightforward. In this sense, the proposed approach is simpler than existing ones that focus on element enrichments, such as the extended finite element method, while share similarities with smeared crack models, and offers the capability to correctly model quasi-brittle failure in post-peak regime at constitutive level. In this work, the formulation is introduced, numerical algorithms described and static and dynamic fracture simulations with complex crack patterns are conducted to demonstrate the capability and advantage of the proposed approach.ARC DP140100945, ARC FT140100408, ARC DE 15010170

    Fracture toughness testing using photogrammetry and digital image correlation

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    Digital image correlation (DIC) is an optical technique commonly used for measuring displacement fields by tracking artificially applied random speckle patterns, which can sometimes be a problem for tracking small-scale displacements. DIC is particularly useful for tracking the crack mouth opening displacement (CMOD) of a notched metallic specimen subjected to three-point bending for fracture toughness determination because the edges of the notch provide the required textural features for DIC without the need for speckle patterns. This simplifies the set-up process as the specimen and stage geometries do not need to account for the placement of a strain gauge. To enhance the accuracy of DIC, this study then successfully downscaled a photogrammetry technique commonly used to track crack propagation in large scale concrete tests so that the pixel coordinates of the captured images can be automatically related to their real-world coordinates, allowing for small scale displacements to be accurately tracked.ARC Linkage Project LP130100111, ARC DECRA DE15010170

    Avaliação de estado nutricional da mangueira Tommy Atkins no submédio do vale do rio São Francisco: estabelecimento das normas DRIS

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    Este trabalho teve por objetivo estabelecer as normas do sistema integrado de diagnose e recomendação (DRIS) para manga, variedade Tommy Atkins. Foram avaliados sessenta e três pomares comerciais representativos do Submédio do Vale do Rio São Francisco, no Nordeste do Brasil. A região não dispõe de um conjunto de normas de diagnose de tecidos foliares para o cultivo, sendo o diagnóstico do estado nutricional e as recomendações de fertilização baseados em faixas de teores de nutrientes em folhas de mangueira cultivadas em diferentes regiões. Foram coletadas amostras de folhas para análise química, antes da aplicação de quebradores de dormência de brotos. As normas DRIS para nutrição das plantas foram estabelecidas com base em um banco de dados criado nesta pesquisa, envolvendo os nutrientes N, P, K, Ca, Mg, B, Cu, Fe, Mn e Zn. Essas normas foram estabelecidas considerando uma subpopulação de plantas com produção igual ou superior a 250 kg/planta, produção essa representativa para as condições ambientais da principal zona produtora de manga do país. Das noventa relações consideradas entre nutrientes, sessenta e duas foram significativas pelo teste F, das quais, quarenta e quatro foram selecionadas como normas para a cultura

    Avaliação do estado nutricional da mangueira Tommy Atkins no submédio do vale do rio São Francisco: cálculo dos índices DRIS

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    O Sistema Integrado de Diagnose e Recomendação, DRIS, é uma ferramenta importante na avaliação do estado nutricional das plantas. Os objetivos do presente trabalho foram avaliar o estado nutricional de pomares de mangueira Tommy Atkins no Submédio do vale do São Francisco, no Brasil, mediante o DRIS, relacionar os índices com os teores foliares de nutrientes e discriminar a ordem de limitação de cada nutriente nas subamostras de alta e de baixa produtividade. Foram amostrados sessenta e três pomares comerciais com sete ou mais anos de idade. Com os teores foliares de macro e micronutrientes foram calculados os índices DRIS, utilizando-se como referência os dados da subpopulação de alta produtividade. Os maiores valores de Índices de Balanço Nutricional médio (IBNm) verificados em pomares de baixa produtividade demonstraram o potencial deste índice na avaliação do estado nutricional da mangueira, e a necessidade de adubações mais criteriosas em tais pomares. A utilização do conceito de potencial de resposta à adubação na interpretação dos índices DRIS mostrou-se uma ferramenta eficaz, principalmente nos pomares de baixa produtividade, onde os desequilíbrios nutricionais foram maiores, confirmando a seqüência de deficiência a excessos, auxiliando o diagnóstico final, indicando os nutrientes que realmente estão em deficiência ou em excesso
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