2,104 research outputs found

    Rotation Curves of Spiral Galaxies and Large Scale Structure of Universe under Generalized Einstein Action

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    We consider an addition of the term which is a square of the scalar curvature to the Einstein-Hilbert action. Under this generalized action, we attempt to explain i) the flat rotation curves observed in spiral galaxies, which is usually attributed to the existence of dark matter, and ii) the contradicting observations of uniform cosmic microwave background and non-uniform galaxy distributions against redshift. For the former, we attain the flatness of velocities, although the magnitudes remain about half of the observations. For the latter, we obtain a solution with oscillating Hubble parameter under uniform mass distributions. This solution leads to several peaks of galaxy number counts as a function of redshift with the first peak corresponding to the Great Wall.Comment: 16 page

    Mycoplasma-like diseases

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    Since 1967, many diseases have been associated with mycoplasma- like microorganisms (MLM), especially when symptoms have been characterized by general plant chlorosis, stunting, excessive proliferation of branches (witches' broom), bud proliferation and disorders of floral organs (phyllody and virescence). Many causal agents are transmitted naturally by leafhoppers to various hosts. Various MLM are known to infect beans, such as legume little-leaf transmitted by Orosius argentatus, witches'-broom, phyllody and virescence. In Colombia, a MLM was detected and is known as machismo or amachamiento, transmitted by Scaphytopius fuliginosus. The symptoms of infection generaly become apparent during flowering and pod development. Control measures include adequate crop rotation and elimination of weed hosts, and the use of insecticides. The symptoms and damage caused by the organisms are illustrated in color. (CIAT)Desde 1967, muchas enfermedades se han asociado con los microorganismos semejantes a micoplasmas (MSM) especialmente cuando los sintomas se han caracterizado por una clorosis general de la planta, raquitismo, proliferacion excesiva de ramas (superbrotamiento) y desordenes en los organos florales (filodia y virescencia). Los saltahojas transmiten en forma natural numerosos agentes causales a diversos hospedantes. Se conocen varios MSM que infectan el frijol como la hoja pequena de las leguminosas transmitida por Orosius argentatus, el superbrotamiento y filodia y virescencia. En Colombia se registro un MSM conocido como machismo o amachamiento transmitido por Scaphytopius fuliginosus. Los sintomas de infeccion generalmente se manifiestan durante el periodo de floracion y formacion de vainas. Las medidas de control incluyen una adecuada rotacion de cultivos y eliminacion de las malezas hospedantes, y el uso de insecticidas. Se ilustran a color los sintomas y danos causados por los organismos. (RA

    Mycoplasma-like diseases

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    Since 1967, many diseases have been associated with mycoplasma- like microorganisms (MLM), especially when symptoms have been characterized by general plant chlorosis, stunting, excessive proliferation of branches (witches' broom), bud proliferation and disorders of floral organs (phyllody and virescence). Many causal agents are transmitted naturally by leafhoppers to various hosts. Various MLM are known to infect beans, such as legume little-leaf transmitted by Orosius argentatus, witches'-broom, phyllody and virescence. In Colombia, a MLM was detected and is known as machismo or amachamiento, transmitted by Scaphytopius fuliginosus. The symptoms of infection generaly become apparent during flowering and pod development. Control measures include adequate crop rotation and elimination of weed hosts, and the use of insecticides. The symptoms and damage caused by the organisms are illustrated in color. (CIAT)Desde 1967, muchas enfermedades se han asociado con los microorganismos semejantes a micoplasmas (MSM) especialmente cuando los sintomas se han caracterizado por una clorosis general de la planta, raquitismo, proliferacion excesiva de ramas (superbrotamiento) y desordenes en los organos florales (filodia y virescencia). Los saltahojas transmiten en forma natural numerosos agentes causales a diversos hospedantes. Se conocen varios MSM que infectan el frijol como la hoja pequena de las leguminosas transmitida por Orosius argentatus, el superbrotamiento y filodia y virescencia. En Colombia se registro un MSM conocido como machismo o amachamiento transmitido por Scaphytopius fuliginosus. Los sintomas de infeccion generalmente se manifiestan durante el periodo de floracion y formacion de vainas. Las medidas de control incluyen una adecuada rotacion de cultivos y eliminacion de las malezas hospedantes, y el uso de insecticidas. Se ilustran a color los sintomas y danos causados por los organismos. (RA

    XANES analyses of the hydrous pyrolysis residues of the IOM from the Murchison carbonaceous chondrite.

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    第3回極域科学シンポジウム/第35回南極隕石シンポジウム 11月30日(金) 国立国語研究所 2階講

    Identificação e purificação de um vírus da poliedrose nuclear da lagarta Spodoptera frugiperda (J.E. Smith, 1797) (Lepidoptera Noctuidae).

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    A lagarta-do-cartucho e considerado uma das principais pragas da cultura do milho e seu controle tem sido feito basicamente pelo uso de inseticidas quimicos. O CNPMS/EMBRAPA considerando as possibilidades de um controle biologico desta praga, tem procurado um virus de granulose. Recentemente isolou-se , a partir de uma lagarta do campo, um virus de poliedrose nuclear (VPN), que tem sido mantido em larvas em condicoes de laboratorio, causando nestas sintomas identicos ao observado no campo. Poliedrose puderam ser purificados a partir de extratos de lagarta infectada atraves de centrifugacao diferencial em um gradiente de densidade de sacarose. Teste de infectividade mostraram que larvas de S. frugiperda, criadas artificialmente, de 3, 6 e 7 dias de idade,alimentadas com suspensoes poliedros, em concentracoes de 2 x 106 ml, tiveram alta taxa de mortalidade (praticamente 100%), exceto as de 7 dias, na menor dose cuja mortandade foi da ordem de 70%. Exames de extratos das lagartas infectadas mostraram a presenca de grande numero de poliedros, mas a identificacao adequada de que se tratava de um virus de poliedrose nuclear, do tipo "multi-enveloped", (MECPN) so pode ser feita atraves de exames de seccoes ultra finas ao microscopio eletronico: nucleos de ectoderma, tecido adiposo e traqueocitos continham grande numero de poliedros e, ocluidas nestes, particulas baciliformes, em geral varias delas envolvidas por um envoltorio comum.Suplemento

    "Enfezamento pálido" e "enfezamento vermelho" na cultura do milho no Brasil Central.

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    Foi constatada alta incidencia de plantas com sintomas de "Enfezamento Palido" e de "Enfezamento vermelho" em lavouras de milho no Brasil Central. Na mesma area observou-se a presenca de cigarrinha Dalbulus maidis em alta densidade. A presenca de espiroplasma foi confirmada apenas em plantas com sintomas de "Enfezamento Palido", atraves de teste DAS-ELISA. Os resultados da analise por PCR indicaram a presenca de fitoplasma em algumas amostras de plantas com sintomas do "enfezamento Vermelho"

    Ocorrência de um Potyvirus associado ao mosaico da açucena-gigante.

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    Plants of spider lily (Crinum sp) showing mosaic symptoms were found in Londrina, Paraná. Electron microscopy examinations revealed flexuous rod shaped particles and lamellar inclusion bodies in the cell cytoplasm. RT-PCR products of 2 kb were amplified by a pair of genus specific primers suggesting the association of a potyvirus, being this the first time a virus infection in this host is reported in Brazil

    Inheritance of tolerance to Cowpea Mild Mottle Virus in soybean.

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    Soybean stem necrosis is caused by Cowpea mild mottle virus (CPMMV) and it has been recognized as an emerging and economically important disease in Brazil. No resistant, but only tolerant cultivars have been identified so far, and their genetic control is still unknown. To investigate the inheritance of soybean tolerance to CPMMV, two crosses between tolerant cultivars (BRS 133 x BRSMT Pintado), and between a susceptible (CD 206) and a tolerant cultivar (BRSMT Pintado) were carried out to obtain F2 and F2:3 generations. Quantitative and qualitative analyses applied to the data from greenhouse evaluations showed that there are at least two distinct major genes determining tolerance to CPMMV, one in the soybean cultivar BRS 133 and another in the cultivar BRSMT Pintado, with predominance of additive genetic effects and heritability levels that allow for efficient selection based on early generation means

    Comparative morpho-anatomical studies of the lesions caused by citrus leprosis virus on sweet orange

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    The leprosis disease shows a viral etiology and the citrus leprosis virus is considered its etiologic agent. The disease may show two types of cytopatologic symptom caused by two virus: nuclear (CiLV-N) and cytoplasmic (CiLV-C) types. The aim of this study was to compare the morpho-anatomical differences in the lesions caused by leprosis virus-cytoplasmic and nuclear types in Citrus sinensis (L.) Osbeck ?Pêra?. Leaf and fruit lesions were collected in Piracicaba/São Paulo (cytoplasmic type) and Monte Alegre do Sul/São Paulo and Amparo/São Paulo (nuclear type). The lesions were photographed and then fixed in Karnovsky solution, dehydrated in a graded ethylic series, embedded in hydroxy-ethyl methacrylate resin (Leica Historesin), sectioned (5?m thick), stained and mounted in synthetic resin. The digital images were acquired in a microscope with digital video camera. Leaf and fruit lesions caused by the two viruses were morphologically distinct. Only the lesion caused by CiLV-N virus presented three well-defined regions. In both lesions there was the accumulation of lipidic substances in necrotic areas that were surrounded by cells with amorphous or droplets protein. Only leaf and fruit lesions caused by CiLV-N virus exhibited traumatic gum ducts in the vascular bundles.Disponivel em: .Acesso em: 18 out. 2010
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