7,978 research outputs found

    Influência da cultura de inverno sobre a produtividade da soja, em sistema de semeadura direta.

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    A Semeadura direta caracteriza-se por um sistema de cultivo conservacionista e com enfoque na manutenção da cobertura do solo. Assim, com o tempo de adoção do sistema observam-se melhorias na qualidade física, química e biológica do solo que resultar no aproveitamento mais racional dos recursos naturais e dos nutrientes. Com objetivo de estudar a influência da cultura de inverno no sistema de rotação foi estudado a resposta da soja após o cultivo de milho safrinha ou de girassol, em função do manejo da adubação fosfatada e potássica. Nas condições estudadas, a produção de soja foi influenciada pela rotação (girassol ou milho), com aumento de 540 kg ha-1 na sucessão girassol/soja (tratamento verão: 40 kg de P2O5 e 80 kg de K2O e inverno: 60 kg de P2O5 e 60 kg de K2O). Dependendo do custo de produção, não é necessário aplicar P2O5 e K2O na cultura de verão para obter altos rendimentos de soja

    Unravelling the non-classicality role in Gaussian heat engines

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    At the heart of quantum thermodynamics lies a fundamental question about what is genuine "quantum" in quantum heat engines. With the help of the P-representability expression of classicality, the degree of non-classicality of a bosonic thermal engine - a quantum heat engine consisting of a single bosonic mode as a working substance coupled to a cold thermal and a hot squeezed thermal bath - is quantified. For two specific protocols, i.e., a quantum Otto and a generalized cycle, we show that the non-classicality is a fundamental resource for genuinely quantum heat engines.Comment: 8 pages, 7 figure

    Tunneling probability for the birth of an universe with radiation in Horava-Lifshitz theory

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    In the present work, we study the birth of a homogeneous and isotropic Friedmann Lemaitre Robertson Walker (FLRW) cosmological model, considering Horava Lifshitz (HL) as the gravitational theory. The matter content of the model is a radiation perfect fluid. In order to study the birth of the universe in the present model, we consider the quantum cosmology mechanism of creation from nothing. In that mechanism, the universe appears after the wavefunction associated to that universe tunnels through a potential barrier. We started studying the classical model. We draw the phase portrait of the model and identify qualitatively all types of dynamical behaviors associated to it. Then, we write the Hamiltonian of the model and apply the Dirac quantization procedure to quantize a constrained theory. We find the appropriate Wheeler-DeWitt equation and solve it using the Wentzel Kramers Brillouin (WKB) approximation. Using the WKB solution, to the Wheeler DeWitt equation, we compute the tunneling probabilities for the birth of that universe (TPWKB). Since the WKB wavefunction depends on the radiation energy (E) and the free parameters coming from the HL theory (gc, gr, gs, gLambda), we compute the behavior of TPWKB as a function of E and all the HL parameters gc, gr, gs, gLambda.Comment: The paper has 20 pages and 9 figure

    Mistura em tanque de boro e herbicidas em semeadura convencional de girassol.

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    Os objetivos deste experimento foi avaliar a resposta do girassol às aplicações de boro (B), isoladas ou em mistura com herbicidas, e o controle de plantas daninhas por meio de experimento conduzido na Embrapa Soja, Londrina-PR. Os tratamentos foram acetochlor (1,92 kg i.a. ha-1), oxyfluorfen (0,36 kg i.a. ha-1), sulfentrazone (0,35 kg i.a.ha-1), trifluralin (1,80 kg i.a. ha-1) e as testemunhas capinada e sem capina. Todos os tratamentos foram aplicados, isoladamente ou em mistura, com 2 kg ha-1 de B (Na2B4O7.10H20 ? bórax e H3BO3 ? ácido bórico). O tratamento mais eficiente foi acetochlor mais ácido bórico; essa combinação resultou em solução mais homogênea da calda de pulverização, quando comparada com os herbicidas mais bórax. O herbicida acetochlor aplicado isoladamente ou em mistura com as duas fontes de B foi eficiente no controle da trapoeraba (Commelina benghalensis), do picão-preto (Bidens pilosa) e da corda-de-viola (Ipomoea grandifolia). Os herbicidas oxyfluorfen e sulfentrazone, aplicados isoladamente ou em misturas com as duas fontes de B, foram eficientes no controle do amendoim-bravo (Euphorbia heterophylla) e da corda-de-viola, respectivamente. É viável a aplicação de boro juntamente com os herbicidas testados nesta pesquisa em mistura em tanque, evitando a deficiência desse micronutriente e controlando as plantas daninhas na cultura do girassol

    Métodos químicos para extração de boro no solo.

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    Adubação da soja: o ocaso do potássio.

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    O objetivo deste trabalho é discutir as possíveis causas para os desequilíbrios nutricionais observados em diferentes lavouras e condições de cultivo, com destaque para o potássio, com sérios danos ao metabolismo das plantas e à produtividade, com consequente redução dos ganhos dos agricultores.Resumo expandido, também apresentado no WORKSHOP CTC AGRICULTURA, 10., 2011, Rio Verde. Geração e difusão de tecnologias: resultados 2011. Rio Verde: Centro Tecnológico Comigo, 2011. p. 10-14

    Systematic evaluation of software product line architectures

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    The architecture of a software product line is one of its most important artifacts as it represents an abstraction of the products that can be generated. It is crucial to evaluate the quality attributes of a product line architecture in order to: increase the productivity of the product line process and the quality of the products; provide a means to understand the potential behavior of the products and, consequently, decrease their time to market; and, improve the handling of the product line variability. The evaluation of product line architecture can serve as a basis to analyze the managerial and economical values of a product line for software managers and architects. Most of the current research on the evaluation of product line architecture does not take into account metrics directly obtained from UML models and their variabilities; the metrics used instead are difficult to be applied in general and to be used for quantitative analysis. This paper presents a Systematic Evaluation Method for UML-based Software Product Line Architecture, the SystEM-PLA. SystEM-PLA differs from current research as it provides stakeholders with a means to: (i) estimate and analyze potential products; (ii) use predefined basic UML-based metrics to compose quality attribute metrics; (iii) perform feasibility and trade-off analysis of a product line architecture with respect to its quality attributes; and, (iv) make the evaluation of product line architecture more flexible. An example using the SEI’s Arcade Game Maker (AGM) product line is presented as a proof of concept, illustrating SystEM-PLA activities. Metrics for complexity and extensibility quality attributes are defined and used to perform a trade-off analysis

    Produção de forragem e qualidade de Brachiaria brizantha cv. Marandu com Azospirillum brasilense e fertilizada com nitrogênio.

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    Thermal recall: Memory-assisted Markovian thermal processes

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    We develop a resource-theoretic framework that allows one to bridge the gap between two approaches to quantum thermodynamics based on Markovian thermal processes (which model memoryless dynamics) and thermal operations (which model arbitrarily non-Markovian dynamics). Our approach is built on the notion of memory-assisted Markovian thermal processes, where memoryless thermodynamic processes are promoted to non-Markovianity by explicitly modelling ancillary memory systems initialised in thermal equilibrium states. Within this setting, we propose a family of protocols composed of sequences of elementary two-level thermalisations that approximate all transitions between energy-incoherent states accessible via thermal operations. We prove that, as the size of the memory increases, these approximations become arbitrarily good for all transitions in the infinite temperature limit, and for a subset of transitions in the finite temperature regime. Furthermore, we present solid numerical evidence for the convergence of our protocol to any transition at finite temperatures. We also explain how our framework can be used to quantify the role played by memory effects in thermodynamic protocols such as work extraction. Finally, our results show that elementary control over two energy levels at a given time is sufficient to generate all energy-incoherent transitions accessible via thermal operations if one allows for ancillary thermal systems.Comment: 20 pages, 14 figures. Substantially extended results with new sections and application. Published versio
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