9,026 research outputs found
Transmissão do amarelão-do-meloeiro pela mosca-branca.
Transmissao do amarelao-do-meloeiro pela mosca-branca.bitstream/CNPAT-2010/8612/1/Ct-093.pd
Gravitational waves from extreme mass-ratio inspirals in Dynamical Chern-Simons gravity
Dynamical Chern-Simons gravity is an interesting extension of General
Relativity, which finds its way in many different contexts, including string
theory, cosmological settings and loop quantum gravity. In this theory, the
gravitational field is coupled to a scalar field by a parity-violating term,
which gives rise to characteristic signatures. Here we investigate how
Chern-Simons gravity would affect the quasi-circular inspiralling of a small,
stellar-mass object into a large non-rotating supermassive black hole, and the
accompanying emission of gravitational and scalar waves. We find the relevant
equations describing the perturbation induced by the small object, and we solve
them through the use of Green's function techniques. Our results show that for
a wide range of coupling parameters, the Chern-Simons coupling gives rise to an
increase in total energy flux, which translates into a fewer number of
gravitational-wave cycles over a certain bandwidth. For space-based
gravitational-wave detectors such as LISA, this effect can be used to constrain
the coupling parameter effectively.Comment: RevTex4, 18 pages, 7 figures, 1 tabl
Superkicks in ultrarelativistic encounters of spinning black holes
We study ultrarelativistic encounters of two spinning, equal-mass black holes
through simulations in full numerical relativity. Two initial data sequences
are studied in detail: one that leads to scattering and one that leads to a
grazing collision and merger. In all cases, the initial black hole spins lie in
the orbital plane, a configuration that leads to the so-called "superkicks". In
astrophysical, quasicircular inspirals, such kicks can be as large as ~3,000
km/s; here, we find configurations that exceed ~15,000 km/s. We find that the
maximum recoil is to a good approximation proportional to the total amount of
energy radiated in gravitational waves, but largely independent of whether a
merger occurs or not. This shows that the mechanism predominantly responsible
for the superkick is not related to merger dynamics. Rather, a consistent
explanation is that the "bobbing" motion of the orbit causes an asymmetric
beaming of the radiation produced by the in-plane orbital motion of the binary,
and the net asymmetry is balanced by a recoil. We use our results to formulate
some conjectures on the ultimate kick achievable in any black hole encounter.Comment: 10 pages, 6 figures, 2 table
Rendimento de espiga verde de milho em resposta à adubação nitrogenada.
O experimento foi executado, sob regime de sequeiro, em solo de textura média, no municÃpio de Teresina, PI, no perÃodo de janeiro a março de 2004. Utilizou-se o delineamento experimental de blocos casualizados com quatro repetições e cinco doses de nitrogênio (0, 50, 100, 150 e 200 kg de N ha-1). Foi observado efeito quadrático para o rendimento de espigas verdes com e sem palha sendo os máximos rendimentos (22.178 e 13.321 kg ha-1) obtidos com 108 e 125 kg de N ha-1, respectivamente. O aumento médio nos rendimentos de espigas verde com e sem palha devido ao nitrogênio foram de 32,4% e 35,3%.Edição dos Anais do 47° Congresso Brasileiro de Olericultura; 4º Simpósio Brasileiro sobre Cucurbitáceas, Porto Seguro, ago. 2007. 1 CD-ROM
Avaliação de hÃbridos de melão quanto à s principais doenças nos estados do Ceará e Rio Grande do Norte.
O presente trabalho foi realizado com o objetivo de avaliar o comportamento de hÃbridos comerciais de melão quanto à reação ao mÃldio (Pseudoperonospora cubensis), ao cancro-da-haste (Didymella bryoniae) e ao oÃdio (Sphaerotheca fuligineaJ. As avaliações para reação a essas doenças foram feitas no Campo Experimental de Pacajus, da Embrapa Agroindústria Tropical (Pacajus, CE), na Fazenda Dantas Empreendimentos (Jaguaruana, CE), na Fazenda Agrosagno (Quixeré, CE), e na Frunort (Carnaubais e Alto dos Rodrigues, RN), nos hÃbridos de melões Cantalupensis (Hy Mark, Durango, PX 20594, Temptation, AF 1749, Vera Cruz, Orange Flesh, CNPAT 27 x 01, CNPAT 27 x 07 e CNPAT 32 x 02) e Inodorus (Gold Mine, Gold Star, TSX 32096, Rochedo, Sunex 7056, Yellow Queen, PX 4910606, AF 464, AF 682 e Yellow King), utilizando-se uma escala de notas, variando de zero (sem sintoma) a quatro (sintoma severo). Com base nos resultados, observou-se que o hÃbrido CNPAT 32 x 02 foi pouco afetado pelo oÃdio e muito infectado por mÃldio e cancro-da-haste, enquanto que os hÃbridos TSX 32096 e PX 4910606 foram medianamente infectados pelo oÃdio e muito afetados pelas demais doenças. Os demais hÃbridos foram severamente infectados por todas as doenças.bitstream/CNPAT-2010/8602/1/Bd-016.pd
Plasmarings as dual black rings
We construct solutions to the relativistic Navier-Stokes equations that
describe the long wavelength collective dynamics of the deconfined plasma phase
of N=4 Yang Mills theory compactified down to d=3 on a Scherk-Schwarz circle
and higher dimensional generalisations. Our solutions are stationary, axially
symmetric spinning balls and rings of plasma. These solutions, which are dual
to (yet to be constructed) rotating black holes and black rings in
Scherk-Schwarz compactified AdS(5) and AdS(6), and have properties that are
qualitatively similar to those of black holes and black rings in flat five
dimensional supergravity.Comment: 40 pages, 40 figures. (v2) Correction to black brane equation of
state, additional reference
Numerical relativity for D dimensional axially symmetric space-times: formalism and code tests
The numerical evolution of Einstein's field equations in a generic background
has the potential to answer a variety of important questions in physics: from
applications to the gauge-gravity duality, to modelling black hole production
in TeV gravity scenarios, analysis of the stability of exact solutions and
tests of Cosmic Censorship. In order to investigate these questions, we extend
numerical relativity to more general space-times than those investigated
hitherto, by developing a framework to study the numerical evolution of D
dimensional vacuum space-times with an SO(D-2) isometry group for D\ge 5, or
SO(D-3) for D\ge 6.
Performing a dimensional reduction on a (D-4)-sphere, the D dimensional
vacuum Einstein equations are rewritten as a 3+1 dimensional system with source
terms, and presented in the Baumgarte, Shapiro, Shibata and Nakamura (BSSN)
formulation. This allows the use of existing 3+1 dimensional numerical codes
with small adaptations. Brill-Lindquist initial data are constructed in D
dimensions and a procedure to match them to our 3+1 dimensional evolution
equations is given. We have implemented our framework by adapting the LEAN code
and perform a variety of simulations of non-spinning black hole space-times.
Specifically, we present a modified moving puncture gauge which facilitates
long term stable simulations in D=5. We further demonstrate the internal
consistency of the code by studying convergence and comparing numerical versus
analytic results in the case of geodesic slicing for D=5,6.Comment: 31 pages, 6 figures; v2 Minor changes and added two references.
Matches the published version in PRD
- …