1,621 research outputs found
Observations of OJ 287 from the Geodetic VLBI Archive of the Washington Correlator
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
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
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.
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.
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
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