1,621 research outputs found

    Observations of OJ 287 from the Geodetic VLBI Archive of the Washington Correlator

    Get PDF
    We present 27 geodetic VLBI maps of OJ 287 obtained from the archive of the Washington correlator. The observations presented here were made between 1990 October and 1996 December. During this period a sequence of six superluminal components has been identified. We measured the proper motion of these components to be approximately 0.5 mas/yr, which is about twice as high as that seen in previous VLBI observations. These results imply a higher component ejection rate than previously observed, in good agreement with the observed occurrences of radio outbursts. We have examined a possible connection between VLBI components and optical flares in the framework of a binary black hole system.Comment: 9 pages, 5 included figures, emulateapj.sty, accepted to The Astrophysical Journa

    A dynamical inconsistency of Horava gravity

    Full text link
    The dynamical consistency of the non-projectable version of Horava gravity is investigated by focusing on the asymptotically flat case. It is argued that for generic solutions of the constraint equations the lapse must vanish asymptotically. We then consider particular values of the coupling constants for which the equations are tractable and in that case we prove that the lapse must vanish everywhere -- and not only at infinity. Put differently, the Hamiltonian constraints are generically all second-class. We then argue that the same feature holds for generic values of the couplings, thus revealing a physical inconsistency of the theory. In order to cure this pathology, one might want to introduce further constraints but the resulting theory would then lose much of the appeal of the original proposal by Horava. We also show that there is no contradiction with the time reparametrization invariance of the action, as this invariance is shown to be a so-called "trivial gauge symmetry" in Horava gravity, hence with no associated first-class constraints.Comment: 28 pages, 2 references adde

    New Pigeon Pea (\u3cem\u3eCajanus Cajan\u3c/em\u3e) Hybrids With Desirable Forage Traits

    Get PDF
    Pigeon pea is a tropical forage legume usually sown in mixed pastures with tropical forage grasses. Most of the available cultivars shows erect and tall plants with poor tillering potential, breakable thick stems, low leaf/stem ratios (fresh/dry matter) and low persistence under animal grazing. It shows a high dry matter production, due to low leaf/stem ratios (Barnes & Addo, 1997). Pigeon pea shows good crude protein levels/dry matter (ranging from 14-23%) and regular in vitro digestibility indexes (52-58%) (Karachi & Matata, 1996); animal consumption is affected by high tannin levels of young leaves. Being a self-pollinated species, the variability for forage traits occurs among cultivars available at germplasm banks. No significant variation is observed for any forage character within a given population. Effective selection and releasing of new genetic materials bearing desirable morpho-agronomic and forage traits is mostly dependent on increases of genetic variation, which may be accomplished through artificial crossings between selected parentals. This research work was aimed at the synthesis of new pigeon pea hybrids, hopefully bearing new desirable forage characters

    Metodologia para definição e priorização de polos de produção para atuação da transferência de tecnologia da Embrapa Mandioca e Fruticultura.

    Get PDF
    Para que as ações de transferência de tecnologias (TT) de instituições de pesquisa e desenvolvimento (P&D) se tornem em uma inovação, ou seja, as tecnologias sejam adotadas pelo setor produtivo, se faz necessário que os esforços sejam cada vez mais focados nos clientes com alto potencial de agente multiplicador (VINHOLIS et al., 2009). No caso da agricultura, em especial a fruticultura, as áreas de cultivo estão distribuídas em praticamente todas as regiões brasileiras, no entanto os cultivos de maior expressão econômica estão concentrados em poucas microrregiões consideradas polos de produção. Entretanto, apesar desta concentração, é necessário o estabelecimento de priorização dos polos de produção visando um maior impacto das ações de transferência de tecnologia

    Caracterização de polos de produção de abacaxi para atuação da transferência de tecnologia na Embrapa Mandioca e Fruticultura.

    Get PDF
    Para tornar as ações de transferência de tecnologias (TT) de instituições de pesquisa e desenvolvimento (P&D) inovadoras, facilitando a adoção das tecnologias pelo setor produtivo, é importante focar as ações nos clientes com alto potencial de agente multiplicador (VINHOLIS et al., 2009). No caso da agricultura, as áreas de cultivo estão distribuídas em praticamente todas as regiões brasileiras, no entanto os cultivos de maior expressão econômica estão concentrados em poucas microrregiões consideradas polos de produção. Assim, é necessário o estabelecimento de priorização dos polos de produção visando um maior impacto das ações de TT
    corecore