4,548 research outputs found

    Interplay of tidal evolution and stellar wind braking in the rotation of stars hosting massive close-in planets

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    This paper deals with the application of the creep tide theory (Ferraz-Mello, Cel. Mech. Dyn. Astron. vol. 116, 109, 2013) to the study of the rotation of stars hosting massive close-in planets. The stars have nearly the same tidal relaxation factors as gaseous planets and the evolution of their rotation is similar to that of close-in hot Jupiters: they tidally evolve towards a stationary solution. However, stellar rotation may also be affected by stellar wind braking. Thus, while the rotation of a quiet host star evolves towards a stationary attractor with a frequency (1+6e21+6e^2) times the orbital mean-motion of the companion, the continuous loss of angular momentum in an active star displaces the stationary solution towards slower values: Active host stars with big close-in companions tend to have rotational periods larger than the orbital periods of their companions. The study of some hypothetical examples shows that because of tidal evolution, the rules of gyrochronology cannot be used to estimate the age of one system with a large close-in companion, no matter if the star is quiet or active, if the current semi-major axis of the companion is smaller than 0.03--0.04 AU. Details on the evolution of the systems: CoRoT LRc06E21637, CoRoT-27, Kepler-75, CoRoT-2, CoRoT-18, CoRoT-14 and on hypothetical systems with planets of mass 1--4 M_Jup in orbit around a star similar to the Sun are given.Comment: 22 pages, 8 figures; Publication in Ap

    Biomonitoramento de abelhas da subtribo euglossina (Hymenoptera: Apoidea) em um plantio de castanheira-do-brasil (Bertholletia excelsa Bonpl., Lecythidaceae) em Belém, Pará.

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    Com a finalidade de conhecer a biodiversidade de abelhas da subtribo Euglossina em áreas cultivadas com castanheira-do-brasil (Bertholletia excelsa Bonpl.), foi realizado monitoramento mensal em: um monocultivo de castanheira-do-brasil, e áreas adjacentes ao plantio monocultivo de mandioca (Manihot esculenta Crantz) e uma área de Capoeira antiga (com cerca de 20 anos), localizadas na Embrapa Amazônia Oriental, no município de Belém, estado do Pará, de setembro/2010 a abril/2011. Foram utilizadas armadilhas aromáticas para a captura de abelhas euglossinas e para outros grupos de abelhas foram utilizados pratos-armadilha (pan-traps). Foram coletadas 1293 abelhas com armadilhas aromáticas, distribuídos entre os gêneros Euglossa, Eulaema, Exaerete, Eufriesea e Trigona. Os pan-traps capturaram um total de 95 espécimes, dos quais 74 pertencentes à família Apidae e outras 21 ainda não identificadas. Em uma analise preliminar foi observado que o prato de cor azul foi o que aprisionou um maior número de abelhas, correspondendo a 84,21% do total de abelhas coletadas, seguido do prato de cor amarelo com 8,42% abelhas coletadas e o branco com 7,37% abelhas. A maior diversidade de espécimes capturada ocorreu no ambiente de capoeira, seguido do monocultivo de mandioca e monocultivo de castanheira-do-brasil.PIBIC-2011

    GEOMETRICAL OPTIMIZATION OF MIXED CONVECTIVE FLOWS OVER TRIANGULAR ARRANGEMENT OF CYLINDERS

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    The present study consists on the numerical evaluation of a triangular arrangement of circular cylinders submitted to transient, two-dimensional, incompressible, laminar and mixed convective flows. The geometrical evaluation is performed by means of Constructal Design. For all simulations it is considered Reynolds and Prandtl numbers of ReD = 100 and Pr = 0.71. Moreover, three different values of Richardson number are investigated: Ri = 0.1 (which represents flows dominated by forced convective), 1.0 (which represents an equilibrium between forced and natural driven forces) and 10.0 (which represents flows with dominance of natural convective). The conservation equations of mass, momentum and energy are solved with the use of Finite Volume Method (FVM). The buoyancy forces are tackled with the Boussinesq approximation. The area occupied by the triangular arrangement of cylinders is a geometric constraint of the problem and the cylinders have the same diameter. The main purpose is to evaluate the effect of Richardson number over the drag coefficient (CD) and Nusselt number (NuD) between the cylinders and the surrounding flow, as well as, over the optimal ratio ST/D (ratio between transversal pitch and the cylinder) for two different values of the ratio SL/D = 1.5 and 2.5 (ratio between longitudinal pitch and the cylinders diameter). Results showed that the effect of ST/D over drag coefficient and Nusselt number is strongly affected by the magnitude of Richardson number. Concerning the Nusselt number, for Ri = 0.1 the optimal geometry which maximizes the NuD is reached for the highest magnitude of ST/D, while for Ri = 10.0 an intermediate optimal ratio of ST/D maximizes the NuD. The Richardson magnitudes also have large influence over the fluid dynamic and thermal behavior of fluid flow for all evaluated geometries. An increase in the ratio SL/D improved the heat exchange of the flow, but decreased the fluid dynamic performance

    Processamento do queijo andino caprino maturado e defumado.

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    bitstream/CNPC-2010/23035/1/cot105.pdfPrática / Processo agropecuário

    Coalhada caprina dessorada e adicionada de polpa de frutos tropicais.

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    bitstream/item/149865/1/CNPC-2010-Cot116.pd

    Processamento de ricota a partir do soro de queijos de cabra.

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    bitstream/CNPC/20867/1/cot82.pd

    Primary and secondary scintillation measurements in a xenon Gas Proportional Scintillation Counter

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    NEXT is a new experiment to search for neutrinoless double beta decay using a 100 kg radio-pure high-pressure gaseous xenon TPC. The detector requires excellent energy resolution, which can be achieved in a Xe TPC with electroluminescence readout. Hamamatsu R8520-06SEL photomultipliers are good candidates for the scintillation readout. The performance of this photomultiplier, used as VUV photosensor in a gas proportional scintillation counter, was investigated. Initial results for the detection of primary and secondary scintillation produced as a result of the interaction of 5.9 keV X-rays in gaseous xenon, at room temperature and at pressures up to 3 bar, are presented. An energy resolution of 8.0% was obtained for secondary scintillation produced by 5.9 keV X-rays. No significant variation of the primary scintillation was observed for different pressures (1, 2 and 3 bar) and for electric fields up to 0.8 V cm-1 torr-1 in the drift region, demonstrating negligible recombination luminescence. A primary scintillation yield of 81 \pm 7 photons was obtained for 5.9 keV X-rays, corresponding to a mean energy of 72 \pm 6 eV to produce a primary scintillation photon in xenon.Comment: 16 pages, 10 figures, accepted for publication in JINS

    Variabilidade genética entre acessos de açaizeiro utilizando marcadores microssatélites.

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    Conduziu-se este trabalho, com o objetivo de caracterizar a variabilidade genética entre 116 acessos de açaizeiro da coleção de germoplasma da Embrapa Amazônia Oriental por marcadores microssatélites (SSR). As reações foram efetuadas com base em 116 amostras de DNA, utilizando sete primers SSR. Os níveis de polimorfismo e as estimativas das distâncias genéticas de Roger foram determinados pelas frequências alélicas e agrupado pelo método UPGMA. Os sete locos SSR revelaram 42 alelos com média de 6 alelos por loco. O conteúdo de informação de polimorfismo (PIC) variou de 0,60 a 0,86 com média de 0,75 e as heterozigosidades observada (Ho) e esperada (He) foram de 0,54 e 0,75, respectivamente. A distância genética média entre todos os acessos foi de 0,61, variando de 0 a 0,96. O método UPGMA formou seis agrupamentos distintos delimitados pela distância genética média (dgm = 0,61). Os acessos de açaizeiro possuem alta diversidade para ser explorada em programas de melhoramento, sendo pelo menos quatro deles altamente divergentes com base nos marcadores SSR

    Avaliação do lixiviado de raquis no suprimento de fósforo durante a fase de crescimento vegetativo da Bananeira 'Prata Gorutuba'.

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    Considerando a importância da bananicultura mundial e a utilização de modelos de produção sustentáveis, que agregam benefícios ao meio ambiente e reduzam custos de produção da cultura, desenvolveu-se um trabalho em ambiente de casa de vegetação na Embrapa Mandioca e Fruticutura, Cruz das Almas - BA, como objetivo de avaliar o efeito nutricional do lixiviado de raquis da bananeira como supridor de fósforo, durante a fase de crescimento vegetativo de plantas da cultivar Prata Gorutuba
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