3,210 research outputs found

    Utilização de resíduos de carvão vegetal associado a fontes orgânicas de nutrientes no manejo sustentável do solo e do guaranazeiro (Paullinia cupana var. sorbilis (Mart.) Ducke) na Amazônia Central.

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    Neste capítulo serão apresentados resultados iniciais de um experimento de longo prazo cujo objetivo é conhecer a influência de resíduos de carvão vegetal, esterco de galinha e farinha de osso nas propriedades químicas e físicas do solo, bem como na sustentabilidade da cultura do guaranazeiro

    Avaliação do estado nutricional de bananais em solos de várzea e terra firme do Amazonas.

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    O objetivo deste trabalho foi de relacionar, a partir da análise foliar, quais os nutrientes mais limitantes para bananicultura no Amazonas, tanto aquela cultivada na várzea, quanto em terra firme

    Repositórios digitais da Embrapa: acesso livre a produção técnico-científica.

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    O Movimento de Acesso Aberto revolucionou a comunicação científica possibilitando novas formas de publicação, divulgação e, principalmente, maior visibilidade da pesquisa. Os repositórios institucionais são produtos deste movimento e caracterizam-se como ferramentas capazes de organizar e tornar acessíveis conteúdos de universidades e instituições produtoras de conhecimento científico. Este trabalho descreve os repositórios institucionais da Embrapa: o Repositório de Acesso Livre à Informação Científica (ALICE) e o serviço de Informação Tecnológica em Agricultura (Infoteca-e), citando suas características, estatísticas de consultas e downloads, procedimentos para depósito e critérios adotados para preservar os documentos digitais nesses repositórios

    Fano resonances in plasmonic core-shell particles and the Purcell effect

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    Despite a long history, light scattering by particles with size comparable with the light wavelength still unveils surprising optical phenomena, and many of them are related to the Fano effect. Originally described in the context of atomic physics, the Fano resonance in light scattering arises from the interference between a narrow subradiant mode and a spectrally broad radiation line. Here, we present an overview of Fano resonances in coated spherical scatterers within the framework of the Lorenz-Mie theory. We briefly introduce the concept of conventional and unconventional Fano resonances in light scattering. These resonances are associated with the interference between electromagnetic modes excited in the particle with different or the same multipole moment, respectively. In addition, we investigate the modification of the spontaneous-emission rate of an optical emitter at the presence of a plasmonic nanoshell. This modification of decay rate due to electromagnetic environment is referred to as the Purcell effect. We analytically show that the Purcell factor related to a dipole emitter oriented orthogonal or tangential to the spherical surface can exhibit Fano or Lorentzian line shapes in the near field, respectively.Comment: 28 pages, 10 figures; invited book chapter to appear in "Fano Resonances in Optics and Microwaves: Physics and Application", Springer Series in Optical Sciences (2018), edited by E. O. Kamenetskii, A. Sadreev, and A. Miroshnichenk

    Concrete damage analysis based on higher-order beam theories using fracture energy regularization

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    This paper presents the numerical damage analysis of concrete structures using higher-order beam theories based on Carrera Unified Formulation (CUF). The concrete constitutive relation is modeled using continuum damage mechanics based on a modified Mazars concrete damage model, in which both the tensile and compressive softening behaviors are regularized with classical fracture energy methodology. An expression is proposed to estimate the characteristic length in higher-order beam theories, to prevent mesh dependency. Both softening constitutive laws and fracture energy calculations are obtained according to Model Code 2010. To assess the efficiency of the proposed model, three classical benchmark quasi-static experiments are taken for validation. From the comparison between numerical and experimental results, the proposed CUF model using continuum damage mechanics can present 3D accuracy with low computational costs and reduce the mesh dependency

    Avaliação de sêmen congelado de bovinos. Provas lenta e rápida de termo-resistência: efeitos sobre a fertilidade.

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    O objetivo do presente trabalho foi avaliar a eficiência de sêmen congelado, submetido as provas rápida e lenta de termo-resistência, sobre a fertilidade de fêmeas da espécie bovina

    Information communication between the library and the extension in the Brazilian Agricultural Research Corporation (Embrapa).

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    The exponential increase of information available and the potential mechanisms for storage and recovery made clear the need to extend the traditional concept of reference services/ mediation of information from libraries. The offer of information is located at the intersection of two fields of information science: the study of demands for profiles, and the organization, processing and availability of information for effective use. This work aims to present the experience related to the development of a project Embrapa Library System (SEB), whose main objective was to build interactive strategies of dissemination of knowledge generated by the Brazilian Agricultural Research Corporation (Embrapa). This project first resulted in a diagnosis of the extension in the state of Rondônia, which supported the creation of online and offline customer service in libraries, creating an information channel with news about the world of scientific and technological information and training for extension in the use of database and digital repositories of Embrapa

    Effects of supplementation of L-carnitine on the body composition of trained and sedentary rats

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    El objetivo del presente estudio es determinar el efecto de la suplementación de L-carnitina sobre la composición corporal de ratas entrenadas y sedentarias. Fueron seleccionadas de forma aleatoria 30 ratas machos Wistar, de 12 semanas de vida, cuyo peso osciló entre 350 a 380 gramos, constituyéndose cuatro grupos de animales: sedentario no suplementado (SNS), sedentario suplementado (SS), entrenado no suplementado (ENS) y entrenado suplementado (ES). El entrenamiento fue realizado con sesiones de carrera en la estera rodante, con duración de una hora y con suplementación oral crónica de L-Carnitina. Ambos protocolos con una duración de 4 semanas. La composición corporal fue evaluada a través de ecuaciones de predicción para determinar la masa libre de grasa (MLG) y masa de grasa (MG). Los resultados muestran que el entrenamiento físico disminuye los valores de la MLG y MG en el grupo ENS, y que la administración de la L-carnitina en forma conjunta con el entrenamiento físico revierte parcialmente la reducción de la MLG en el grupo ES. Finalmente se concluye que el ejercicio físico debe ser realizado juntamente con la suplementación de L-carnitina, permitiendo una disminución de la MG y mantener los niveles de MLG en ratas en proceso de crecimiento.The aim of this study is to determine the effect of L-carnitine supplementation on body composition of trained and sedentary rats. Were randomly selected 30 male Wistar rats of 12 weeks of age, whose weight ranged between 350 to 380 grams, four groups of animals: sedentary non-supplemented (SNS), sedentary supplemented (SS), trained not supplemented (ENS) trained and supplemented (ES). The training was done with sessions running on a treadmill, lasting an hour and chronic oral supplementation of L-carnitine. Both protocols with a duration of 4 weeks. Body composition was assessed by prediction equations to determine fat-free (FFM) and fat mass (FM). The results show that physical training decreases the values of FFM and FM in the ENS group, and that the administration of L-carnitine together with physical training partially reverses the reduction of MLG in ES. Finally concluded that physical exercise should be conducted jointly with the supplementation of L-carnitine, allowing a reduction in the MG and maintain levels in rats MLG growth process.Peer Reviewe
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