41,478 research outputs found
Detection of new eruptions in the Magellanic Clouds LBVs R 40 and R 110
We performed a spectroscopic and photometric analysis to study new eruptions
in two luminous blue variables (LBVs) in the Magellanic Clouds. We detected a
strong new eruption in the LBV R40 that reached in 2016, which is
around mag brighter than the minimum registered in 1985. During this new
eruption, the star changed from an A-type to a late F-type spectrum. Based on
photometric and spectroscopic empirical calibrations and synthetic spectral
modeling, we determine that R\,40 reached ~K
during this new eruption. This object is thereby probably one of the coolest
identified LBVs. We could also identify an enrichment of nitrogen and r- and
s-process elements. We detected a weak eruption in the LBV R 110 with a maximum
of mag in 2011, that is, around mag brighter than in the
quiescent phase. On the other hand, this new eruption is about mag
fainter than the first eruption detected in 1990, but the temperature did not
decrease below 8500 K. Spitzer spectra show indications of cool dust in the
circumstellar environment of both stars, but no hot or warm dust was present,
except by the probable presence of PAHs in R\,110. We also discuss a possible
post-red supergiant nature for both stars
BRS Vitória: nova cultivar de bananeira do subgrupo prata para o agronegócio no Estado do Amazonas.
CaracterÃsticas fitotécnicas da cultivar BRS Vitória. Reação da cultivar Vitória à s principais doenças e pragas.bitstream/item/64259/1/ComTec-34-2005.pd
BRS Japira: cultivar de bananeira resistente à sigatoka-negra e à antracnose para o Estado do Amazonas.
CaracterÃsticas fitotécnicas da cultivar BRS Japira. Reação da cultivar Japira à s principais doenças e pragas.bitstream/item/64261/1/ComTec-35-2005.pd
Levantamento da incidência do amarelinho ou CVC nos pomares de citros no Estado do Amazonas.
Levantamento da doenca amarelinha causada pela bacteria Xylella fastidiosa nos pomares de citros no Estado do Amazonas (Brasil).bitstream/item/83143/1/Pesquisa-99-1999.pd
Controle quÃmico da Sigatoka negra da bananeira. I - Trifloxistrobin, Propiconazole e Difenoconazole.
A Sigatoka negra, causada pelo fungo Mycosphaerella fijiensis (fase anamórfica: Paracercospora fijiensis (Morelet) Deighton, é a doença mais grave da bananeira, causando perdas de 100% da produção, quando não se efetua o controle. Os fungicidas trifloxistrobin, difenoconazole e propiconazole, foram eficientes no controle da Sigatoka negra, aplicados a intervalos regulares de 14 dias.bitstream/CPAA-2009-09/6808/1/ComTec-7.pd
Epidemiologia da sigatoka negra da bananeira (Musa spp).
Estudo sobre o progresso da sigatoka negra em bananeiras, associado a variacoes e/ou efeitos de variaveis climaticas, que permitem prever as epocas de maior severidade e/ou surtos da doenca, de forma a estabelecer estrategias de controle mais viaveis do ponto de vista economico-ambiental no Estado do Amazonas (Brasil).bitstream/item/76938/1/CPAA-PESQ.-AND.-34-99.pd
Teleparallel Theories of Gravity: Illuminating a Fully Invariant Approach
Teleparallel gravity and its popular generalization gravity can be
formulated as fully invariant (under both coordinate transformations and local
Lorentz transformations) theories of gravity. Several misconceptions about
teleparallel gravity and its generalizations can be found in the literature,
especially regarding their local Lorentz invariance. We describe how these
misunderstandings may have arisen and attempt to clarify the situation. In
particular, the central point of confusion in the literature appears to be
related to the inertial spin connection in teleparallel gravity models. While
inertial spin connections are commonplace in special relativity, and not
something inherent to teleparallel gravity, the role of the inertial spin
connection in removing the spurious inertial effects within a given frame of
reference is emphasized here. The careful consideration of the inertial spin
connection leads to the construction of a fully invariant theory of
teleparallel gravity and its generalizations. Indeed, it is the nature of the
spin connection that differentiates the relationship between what have been
called good tetrads and bad tetrads and clearly shows that, in principle, any
tetrad can be utilized. The field equations for the fully invariant formulation
of teleparallel gravity and its generalizations are presented and a number of
examples using different assumptions on the frame and spin connection are
displayed to illustrate the covariant procedure. Various modified teleparallel
gravity models are also briefly reviewed.Comment: v2: 72 pages, revised version, references added, matches published
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