30 research outputs found

    Decomposition of Cattle Dung on Mixed Grass-Legume Pastures

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    Animal excreta contribute positively to nutrient cycling and can improve the quality of soil (Dubeux et al. 2009, Carvalho et al. 2010). Cattle excrement, when evenly distributed over a pasture, can help to maintain plant nutrition without the application of fertilizers. The introduction of legumes intercropped with grasses benefits the soil by means of nitrogen fixation. Also, when ruminant animals eat legumes, the excrement produced may have lower C:N, C:P, lignin:N and lignin:P ratios promoting better nutrient return to the soil compared to when cattle eat only grass. Given the importance of nutrient return and decomposition time of cattle excreta on pastures, the objective of this study was to evaluate the decomposition of excrement of heifers managed in mixed grass-shrubby legume pastures and grass-only pastures

    Animal Performance and Pasture Characteristics of \u3cem\u3eBrachiaria decumbens\u3c/em\u3e Stapf., \u3cem\u3eGliricidia sepium\u3c/em\u3e (Jacq.) Steud, and \u3cem\u3eMimosa caesalpiniifolia\u3c/em\u3e Benth. in Silvipastoral Systems

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    Grasslands are the major source of feed for ruminants (Zanine 2005). Seasonality of production, however, is a constraint in forage-based systems. Silvopastoril systems combine different components (animals, trees, and forages) into one integrated system and may improve forage distribution across seasons. Resource use is usually more efficient both spatially and temporally, increasing land use efficiency (Nair 1993). Tree legumes present potential for silvopastoril systems because they can fix N from the atmosphere, improve cattle diet, and lead to a faster N cycle. In addition, trees provide shade and may reduce heat stress for grazing animals in warm-climate grasslands. Legume trees are commonly found in warm-season climates and present potential for use in silvopastoril systems. This research studied the animal performance and pasture characteristics of signal grass (Brachiaria decumbens Stapf.) in pure stand or in silvopastoril systems with Gliricidia sepium (Jacq.) Steud or Mimosa caesalpinifolia Benth

    Association between Zika virus infection and microcephaly in Brazil, January to May, 2016: preliminary report of a case-control study.

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    BACKGROUND: The microcephaly epidemic, which started in Brazil in 2015, was declared a Public Health Emergency of International Concern by WHO in 2016. We report the preliminary results of a case-control study investigating the association between microcephaly and Zika virus infection during pregnancy. METHODS: We did this case-control study in eight public hospitals in Recife, Brazil. Cases were neonates with microcephaly. Two controls (neonates without microcephaly), matched by expected date of delivery and area of residence, were selected for each case. Serum samples of cases and controls and cerebrospinal fluid samples of cases were tested for Zika virus-specific IgM and by quantitative RT-PCR. Laboratory-confirmed Zika virus infection during pregnancy was defined as detection of Zika virus-specific IgM or a positive RT-PCR result in neonates. Maternal serum samples were tested by plaque reduction neutralisation assay for Zika virus and dengue virus. We estimated crude odds ratios (ORs) and 95% CIs using a median unbiased estimator for binary data in an unconditional logistic regression model. We estimated ORs separately for cases with and without radiological evidence of brain abnormalities. FINDINGS: Between Jan 15, 2016, and May 2, 2016, we prospectively recruited 32 cases and 62 controls. 24 (80%) of 30 mothers of cases had Zika virus infection compared with 39 (64%) of 61 mothers of controls (p=0·12). 13 (41%) of 32 cases and none of 62 controls had laboratory-confirmed Zika virus infection; crude overall OR 55·5 (95% CI 8·6-∞); OR 113·3 (95% CI 14·5-∞) for seven cases with brain abnormalities; and OR 24·7 (95% CI 2·9-∞) for four cases without brain abnormalities. INTERPRETATION: Our data suggest that the microcephaly epidemic is a result of congenital Zika virus infection. We await further data from this ongoing study to assess other potential risk factors and to confirm the strength of association in a larger sample size. FUNDING: Brazilian Ministry of Health, Pan American Health Organization, and Enhancing Research Activity in Epidemic Situations

    Association between microcephaly, Zika virus infection, and other risk factors in Brazil: final report of a case-control study.

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    BACKGROUND: A Zika virus epidemic emerged in northeast Brazil in 2015 and was followed by a striking increase in congenital microcephaly cases, triggering a declaration of an international public health emergency. This is the final report of the first case-control study evaluating the potential causes of microcephaly: congenital Zika virus infection, vaccines, and larvicides. The published preliminary report suggested a strong association between microcephaly and congenital Zika virus infection. METHODS: We did a case-control study in eight public maternity hospitals in Recife, Brazil. Cases were neonates born with microcephaly, defined as a head circumference of 2 SD below the mean. Two controls without microcephaly were matched to each case by expected date of delivery and area of residence. We tested the serum of cases and controls and the CSF of cases for detection of Zika virus genomes with quantitative RT-PCR and for detection of IgM antibodies with capture-IgM ELISA. We also tested maternal serum with plaque reduction neutralisation assays for Zika and dengue viruses. We estimated matched crude and adjusted odds ratios with exact conditional logistic regression to determine the association between microcephaly and Zika virus infection. FINDINGS: We screened neonates born between Jan 15 and Nov 30, 2016, and prospectively recruited 91 cases and 173 controls. In 32 (35%) cases, congenital Zika virus infection was confirmed by laboratory tests and no controls had confirmed Zika virus infections. 69 (83%) of 83 cases with known birthweight were small for gestational age, compared with eight (5%) of 173 controls. The overall matched odds ratio was 73·1 (95% CI 13·0-∞) for microcephaly and Zika virus infection after adjustments. Neither vaccination during pregnancy or use of the larvicide pyriproxyfen was associated with microcephaly. Results of laboratory tests for Zika virus and brain imaging results were available for 79 (87%) cases; within these cases, ten were positive for Zika virus and had cerebral abnormalities, 13 were positive for Zika infection but had no cerebral abnormalities, and 11 were negative for Zika virus but had cerebral abnormalities. INTERPRETATION: The association between microcephaly and congenital Zika virus infection was confirmed. We provide evidence of the absence of an effect of other potential factors, such as exposure to pyriproxyfen or vaccines (tetanus, diphtheria, and acellular pertussis, measles and rubella, or measles, mumps, and rubella) during pregnancy, confirming the findings of an ecological study of pyriproxyfen in Pernambuco and previous studies on the safety of Tdap vaccine administration during pregnancy. FUNDING: Brazilian Ministry of Health, Pan American Health Organization, and Enhancing Research Activity in Epidemic Situations

    Leituras e leitores de Richard Morse: a trajetória de um livro sobre a formação da metrópole paulista

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    De comunidade à metrópole: a biografia de São Paulo, was first published in 1954 and then re published in 1970 as Formação histórica de São Paulo: de comunidade à metrópole. Written by a young US researcher fascinated by Latin America, this material was originally submitted as his PhD thesis at Columbia University in 1952. Since then, Richard Morse's (1922-2001) work has come a long way and is now considered a primary reference in the history of urban development of São Paulo. This article briefly recovers the reader's response when Morse's research was first published, and how it ensured the book's importance in the Brazilian historiography. The aim is to draw a parallel trajectory of the book and its author - the young researcher at Columbia who became a professor of Latin American History at Yale - and to discuss the meanings regarding its importance in São Paulo's historiography as well as its contribution to a better understanding of the city.O livro De comunidade à metrópole: a biografia de São Paulo, publicado em 1954 e reeditado em 1970 com um novo título, Formação histórica de São Paulo: de comunidade à metrópole, foi escrito por um jovem norte-americano encantado com a América Latina, tendo sido inicialmente apresentado como tese de doutorado na Universidade de Columbia, em 1952. Desde então, essa obra de Richard Morse (1922-2001) percorreu um longo caminho, sendo hoje considerada "um clássico" sobre a evolução urbana da capital paulista. Retoma-se sinteticamente aqui a recepção da publicação, recuperando leitores e leituras que acabaram por garantir ao livro de Morse esse lugar na historiografia paulistana e brasileira. Busca-se, desse modo, traçar um paralelo entra a trajetória do livro e a de seu autor - que de jovem investigador em Columbia torna-se professor de História da América Latina na Universidade de Yale - para discutir o sentido do livro na historiografia e na própria interpretação que o livro fundaria sobre a cidade de São Paulo

    Projeto evolutivo de circuitos combinacionais quânticos

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    Enquanto os avanços em hardware quântico ocorrem em passos modestos, simuladores rodando em computadores clássicos permitem um avanço um pouco mais rápido na construção de algoritmos quânticos. Dada uma matriz unitária que efetue determinada operação, obter o circuito quântico equivalente de uma tarefa não trivial que pode ser modelada como um problema de busca. Uma abordagem genérica que torne possível a síntese automática destes circuitos permitiria não são o estudo e desenvolvimento de novos algoritmos, mas também avaliar o custo-benefício relacionado ao tamanho e complexidade do circuito. Um problema comum encontrado em trabalhos anteriores de o uso de portas quânticas controladas de unitárias gerais, em razão da dificuldade de implementação física de tais portas. Neste trabalho apenas portas controladas do tipo CNOT são utilizadas, resultando em circuitos mais próximos da realidade física. Um algoritmo evolutivo de proposto para decompor uma matriz unitária em uma sequência equivalente de portas quânticas. O método de testado para encontrar decomposições das unitárias de Toffoli, da transformada quântica de Fourier de dois qubits e da moeda para o caminhante quântico. Os resultados mostram que o algoritmo é efi ciente em encontrar as soluções, e que o problema da convergência prematura de evitado ao se utilizar populações que evoluem em paraleloWhile advances in quantum hardware occur in modest steps, simulators running on classical computers allow a slightly faster advance in the construction of quantum algorithms. Given a unitary matrix that performs a given operation, obtaining the equivalent quantum circuit is a non-trivial task that can be modeled as a search problem. A generic approach that makes possible the automatic synthesis of these circuits would allow not only the study and development of new algorithms, but also to evaluate the cost-bene t related to the size and complexity of the circuit. A common problem found in previous works is the use of quantum controlled gates from general unitaries, due to the diculty of physically implementing such gates. In this work, only CNOT controlled gates are used, resulting in circuits closer to physical reality. An evolutionary algorithm is proposed to decompose a unitary matrix into an equivalent sequence of quantum gates. The method is tested to nd decompositions of the Toffoli unitary, the two qubits quantum Fourier transform and the coin for the quantum walker. The results show that the algorithm is eficient in nding the solutions, and that the problem of premature convergence is avoided when populations are evolved in parallelCoordenação de Aperfeiçoamento de Pessoal de Nível SuperiorConselho Nacional de Desenvolvimento Científico e TecnológicoInstituto Presbiteriano Mackenzi
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