Gravitational wave recoil in Robinson-Trautman spacetimes

We consider the gravitational recoil due to non-reflection-symmetric gravitational wave emission in the context of axisymmetric Robinson-Trautman spacetimes. We show that regular initial data evolve generically into a final configuration corresponding to a Schwarzschild black-hole moving with constant speed. For the case of (reflection-)symmetric initial configurations, the mass of the remnant black-hole and the total energy radiated away are completely determined by the initial data, allowing us to obtain analytical expressions for some recent numerical results that have been appeared in the literature. Moreover, by using the Galerkin spectral method to analyze the non-linear regime of the Robinson-Trautman equations, we show that the recoil velocity can be estimated with good accuracy from some asymmetry measures (namely the first odd moments) of the initial data. The extension for the non-axisymmetric case and the implications of our results for realistic situations involving head-on collision of two black holes are also discussed.Comment: 9 pages, 6 figures, final version to appear in PR

Black-hole horizons as probes of black-hole dynamics I: post-merger recoil in head-on collisions

The understanding of strong-field dynamics near black-hole horizons is a long-standing and challenging prob- lem in general relativity. Recent advances in numerical relativity and in the geometric characterization of black- hole horizons open new avenues into the problem. In this first paper in a series of two, we focus on the analysis of the recoil occurring in the merger of binary black holes, extending the analysis initiated in [1] with Robinson- Trautman spacetimes. More specifically, we probe spacetime dynamics through the correlation of quantities defined at the black-hole horizon and at null infinity. The geometry of these hypersurfaces responds to bulk gravitational fields acting as test screens in a scattering perspective of spacetime dynamics. Within a 3 + 1 approach we build an effective-curvature vector from the intrinsic geometry of dynamical-horizon sections and correlate its evolution with the flux of Bondi linear momentum at large distances. We employ this setup to study numerically the head-on collision of nonspinning black holes and demonstrate its validity to track the qualita- tive aspects of recoil dynamics at infinity. We also make contact with the suggestion that the antikick can be described in terms of a "slowness parameter" and how this can be computed from the local properties of the horizon. In a companion paper [2] we will further elaborate on the geometric aspects of this approach and on its relation with other approaches to characterize dynamical properties of black-hole horizons.Comment: final version published on PR

Crescimento de Bertholletia excelsa em floresta nativa no Mato Grosso.

Resumo

Criação de Chrysoperla externa para o controle biológico de pragas do algodoeiro.

bitstream/CNPA-2009-09/14457/1/CIRTEC36.pd

Animal Production from Tropical Pastures Renovated by Subsoiling and Fertilization in the Cerrados of Brazil

A grazing trial was conducted, to study the effects of fertilization on the maintenance of the productivity of four tropical grasses. The paddocks were subsoiled, and dived into halves: one (LF1) received 400 kg/ha of a fertilizer formula 0-20-20.and the other (LF2) 800 kg/ha of the same fertilizers, in January 1995. Annually, 50 kg/ha of N was applied. The productivity on LF2 pastures was greater than that on FL1 pastures, averaging 520 and 410 kg of liveweight gain/ha/year. A double strategy should be followed to sustain animal production in the savanna: maintain soil P over a critical value of 3.0 mg P(Mehlich-1)/dm3, and annual N application

Micropedologia de um Argissolo amarelo com horizontes antrópicos (Terra Preta de Índio) na Amazônia Central.

Estudos micropedológicos foram carreados em Terra Preta de Índio (TPI) com o objetivo de elucidar os processos envolvidos em sua gênese, bem como suas formas de utilização pré-colombiana. Blocos indeformados de solo foram coletados por horizonte e em suas respectivas transições em um perfil de Argissolo Amarelo A Antrópico (TPI) localizado no município de Iranduba, AM. As lâminas delgadas confeccionadas a partir dos blocos foram descritas por meio de microscopia óptica. Os resultados mostraram que os processos envolvidos na gênese desse solo envolveram: i) condições pedoambientais diferentes das atuais (pedorrelíquias - nódulos ferruginosos); ii) argiluviação, indicada por revestimentos de ferri-argilãs orientados na parede de poros entre agregados e canais; iii) migração de ferro impregnando o fundo matricial (cutãs de difusão); iv) bioturbação, atestada por preenchimento de poros por pelotas fecais e microagregação zoogenética e v) antropismo, que contribuiu com a queima de resíduos (partículas de carvões) e descarte de artefatos cerâmicos. A análise dos fragmentos cerâmicos corroborou a utilização de cauixi (Tubella reticulata e Parnula betesil) e cariapé (Bignoniacea) como antiplástico para o seu fabrico

Microtomografia aplicada ao estudo do selamento superficial de solos.

bitstream/CNPDIA/10258/1/PA25_98.pd

Altura e diâmetro de plantas de um clone de eucalipto e produção de massa seca de P. maximum cv. Massai na integração lavoura-pecuária-floresta.

O objetivo neste trabalho foi avaliar a altura e diâmetro de plantas de eucalipto e a produção de massa seca do P. maximum cv. Massai (capim-massai) e sorgo forrageiro BRS800 cultivados em SILPF no estágio inicial de implantação do sistema

BORAZANs: Tunable Fluorophores Based on 2-(Pyrazolyl)aniline Chelates of Diphenylboron

The reaction between 2-pyrazolyl-4-X-anilines, H(pzAnX), (X = para-OMe (L1), Me (L2), H (L3), Cl (L4), CO2Et (L5), CF3 (L6), CN (L7)) and triphenylboron in boiling toluene affords the respective, highly emissive N,N‘-boron chelate complexes, BPh2(pzAnX) (X = para-OMe (1), Me (2), H (3), Cl (4), CO2Et (5), CF3 (6), CN (7)) in high yield. The structural, electrochemical, and photophysical properties of the new boron complexes can be fine-tuned by varying the electron-withdrawing or -donating power of the para-aniline substituent (delineated by the substituent\u27s Hammett parameter). Those complexes with electron-withdrawing para-aniline substituents such as CO2Et (5), CF3 (6), and CN (7) have more planar chelate rings, more ‘quinoidal\u27 disortion in the aniline rings, greater chemical stability, higher oxidation potentials, and more intense (φF = 0.81 for 7 in toluene), higher-energy (blue) fluorescent emission compared to those with electron-donating substituents. Thus, for 1 the oxidation potential is 0.53 V versus Ag/AgCl (compared to 1.12 V for 7), and the emission is tuned to the yellow-green but at an expense in terms of lower quantum yields (φF = 0.07 for 1 in toluene) and increased chemical reactivity. Density functional calculations (B3LYP/6-31G*) on PM3 energy-minimized structures of the ligands and boron complexes reproduced experimentally observed data and trends and provided further insight into the nature of the electronic transitions