19,737 research outputs found
Respostas metabólicas de timbó (Derris urucu), submetido a diferentes níveis de deficiência hídrica.
Cosmological constant constraints from observation-derived energy condition bounds and their application to bimetric massive gravity
Among the various possibilities to probe the theory behind the recent
accelerated expansion of the universe, the energy conditions (ECs) are of
particular interest, since it is possible to confront and constrain the many
models, including different theories of gravity, with observational data. In
this context, we use the ECs to probe any alternative theory whose extra term
acts as a cosmological constant. For this purpose, we apply a model-independent
approach to reconstruct the recent expansion of the universe. Using Type Ia
supernova, baryon acoustic oscillations and cosmic-chronometer data, we perform
a Markov Chain Monte Carlo analysis to put constraints on the effective
cosmological constant . By imposing that the cosmological
constant is the only component that possibly violates the ECs, we derive lower
and upper bounds for its value. For instance, we obtain that and within,
respectively, and confidence levels. In addition, about
30\% of the posterior distribution is incompatible with a cosmological
constant, showing that this method can potentially rule it out as a mechanism
for the accelerated expansion. We also study the consequence of these
constraints for two particular formulations of the bimetric massive gravity.
Namely, we consider the Visser's theory and the Hassan and Roses's massive
gravity by choosing a background metric such that both theories mimic General
Relativity with a cosmological constant. Using the
observational bounds along with the upper bounds on the graviton mass we obtain
constraints on the parameter spaces of both theories.Comment: 11 pages, 4 figures, 1 tabl
Avaliação preliminar de clones de seringueira em Mazagão-AP.
Para indicar germoplasma adaptados e de elevada produtividade, esta sendo deselvolvido um ensaio de competição com 15 clones de seringueira de diferentes origens.bitstream/item/65107/1/AP-1989-avaliacao-preliminar-clones-seringueiras.pd
Influência de meio de cultura e genótipo na embriogênese somática indireta de Coffea arabica L.
Seleção de sabiá (Mimosa caesalpiniifolia) sem acúleos no Meio-Norte.
Disponivel via Word Wide Web. http: www.cpatsa.embrapa.br
- …