2,378 research outputs found

    On the rr-stability of spacelike hypersurfaces

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    In this paper we study the strong stability of spacelike hypersurfaces with constant rr-th mean curvature in Generalized Robertson-Walker spacetimes of constant sectional curvature. In particular, we treat the case in which the ambient spacetime is the de Sitter space

    Ejercicio sobre el "sarilho" en los primeros cursos de la enseñanza básica : análisis de la discusión

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    En este trabajo presentamos el análisis de la discusión de un grupo de estudiantes de segundo año de enseñanza básica sobre la resolución de un ejercicio de razonamiento sobre la máquina simple «sarilho». Ese ejercicio está basado en la historia «Tão Simples e Tão Úteis» (Barbosa Lima, 1997) leída por todo el grupo bajo la orientación de la profesora. Nuestro análisis tiene como base el estudio de la transcripción de las intervenciones de los estudiantes en el momento de socializar sus hipótesis con sus compañeros.In this assignment we present the analysis of a group discussion involving second grade students, concerning the reel simple machine. This exercise has been based on a part of the story from the book «So Simple, So Useful» (Barbosa Lima, 1997), which was read by the group, guided by their teacher. Our analysis is based on a study of the transcription of students' participations as they shared their perceptions with classmates

    Una propuesta : enseñar física a niños de grados elementales

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    With the purpose of doing a previous presentation on Physics issues to children in their school initial steps, we intend to discuss a proposition using the scope of some tales as an appropriate tool to reach that objective. Our paper deals with two experiences. We have presented and established some comments in two of our municipality of Rio de Janeiro schools. In one of them, a public school which deals with students of a lower economic class and another one, a private school dealing with students of a middle economic class. In order to assist achvely in the process of Physics teaching, as a sequence of our proposition, we are describing one of our experiences, which is being developed with educators responsible for students of these levels

    Pesos ao nascimento, a desmama e ao sobreano de animais Nelores e cruzados Canchim X Nelore.

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    Com o objetivo de avaliar o potencial da raça Canchim em cruzamentos, estudaram-se os pesos ao nascimento, a desmama e ao sobreano de bezerros Nelores e cruzados Canchim X Nelore, nascidos durante o período de 1987 a 1990 e criados em regime de pastagens na região Oeste do Estado de São Paulo.Resumo

    Triguilho na alimentação de suínos.

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    Avaliação da resistência de 47 acessos de mangueira aos fungos Fusicoccum aesculis e Neofusicoccum parvum.

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    A mangicultura praticada no Submédio do Vale do São Francisco é considerada um dos principais destaques no comércio externo do País. Dentre as diversas variedades cultivadas, a Tommy Atkins é a que representa a maior parte das exportações. Entretanto, a magnitude das perdas por podridões pós--colheita, causadas por fungos Botryosphaeriaceae, é sempre uma grande preocupação para exportadores e importadores da fruta. A busca por métodos de controle mais eficazes e limpos é uma tendência mundial. Nesse sentido, o objetivo deste trabalho foi avaliar a reação de frutos, de 47 acessos de mangueiras, quanto à resistência aos fungos Fusicoccum aesculis e Neofusicoccum parvum. As inoculações foram realizadas mediante deposição de disco do meio de cultura batata-dextrose-ágar (BDA), contendo estruturas do patógeno sobre duas posições opostas na região equatorial da manga, mantido, posteriormente, por 24 horas em câmara úmida. Foram realizadas medições das lesões até o sétimo dia, com uma régua milimetrada. Com os registros dos crescimentos das lesões, foram calculadas as taxas diárias de crescimento da lesão (TDCL?s) para cada acesso. As maiores TDCLs foram observadas nos acessos ?Roxa? e ?Lita?, quando inoculados com F. aesculis, e nos acessos Roxa, Ruby, Papo de peru, CPAC 22/93, ?Pingo-de-ouro, Pêssego e M13269, quando inoculados com N. parvum. Os acessos Nego-não-chupa, Manga-d'água, Juazeiro VI, Juazeiro VII e Favo-de-mel foram os que apresentaram, concomitantemente, as menores TDCLs para ambos os patógenos e diferenças significativas em relação aos demais acessos

    Relationships between energy cost, swimming velocity and speed fluctuation in elite butterfliers

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    In swimming science, economy of movement is an interesting field of research. Several investigations have been conducted to understand the role of bioenergetical profile to performance. Most of those studies focused exclusively on the contribution of The individual correlations between E-tot and v ranged from R=0.95 aerobic system to produce energy for movement, even though all competitive swimming events also require significant (p=0.05) to R=0.90 (p<0.01). For pooled data the relationship was contribution from anaerobic energetic system to cover total energy expenditure. R=0.70 (p<0.01). The individual correlations between EC and d

    Análise econômica da utilização do triguilho para suínos.

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    Induction of resistance to Xanthomonas campestris pv. viticola in grapevine plants.

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    The objective of this work was to evaluate the effect of Saccharomyces cerevisiae (SC), Acibenzolar-S-Methyl (ASM), organic acids and polyphenols (OAP) and potassium silicate (SiK) on protecting grapevine plants (cv. Redglobe) from Xanthomonas campestris pv. viticola. Four application rates for each product (SC at 2.0, 2.50, 3.0, 3.50 and 4.0 mL 100 L-1; ASM and OAP at 2.50, 3.00, 3.50, 4.50 and 6.00 mL 100 L-1 and SiK at 5.00, 6.50, 7.50 and 8.50 mL 100 L-1) in different application times (0, 5, 10, and 15 days before inoculation), and the enzymatic activity of peroxidases, phenylalanine ammonia-lyase and ?-1,3 glucanases were evaluated. Plants were inoculated with a bacterial suspension of 5 x 108 CFU mL-1 by rubbing with gauze. The epidemiological variables incidence (INC), severity (SEV) and area under the disease progress curve (AUDPC) were assessed. The treatment with ASM had the lowest averages of INC (38%) and SEV (1.52%) from 3 g 100 L-1. The application of 4.5 mL 100 L-1 of OAP reduced the plant disease in 52% of INC and 2.45% of SEV. SiK and SC presented no significant reduction in these variables compared to control. The ASM applied 15 days before the inoculation (DBI) reduced the disease in 91.31% and the APO in 73.34%, while SC and SiK reduced the disease in 67.49 and 60.11%, respectively, with applications at 5 DBI. There was no increase of peroxidase activity in any of the treatments. There was a significant increase in activity of ?-1,3 glucanases and phenylalanine ammonia-lyase in plants treated with ASM at 15 DBI, indicating an influence on the induction of resistance of plants to this disease

    Frequência de aplicação foliar de micronutrientes em arroz de terras altas.

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    Os objetivos deste documento foram relatar os aspectos importantes a serem considerados na tomada de decisão para a aplicação foliar de micronutrientes e, apresentar os resultados de um estudo preliminar sobre a suplementação foliar de micronutrientes em arroz de terras altas.bitstream/CNPAF-2009-09/28008/1/comt_166.pd
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