A Compound model for the origin of Earth's water

One of the most important subjects of debate in the formation of the solar system is the origin of Earth's water. Comets have long been considered as the most likely source of the delivery of water to Earth. However, elemental and isotopic arguments suggest a very small contribution from these objects. Other sources have also been proposed, among which, local adsorption of water vapor onto dust grains in the primordial nebula and delivery through planetesimals and planetary embryos have become more prominent. However, no sole source of water provides a satisfactory explanation for Earth's water as a whole. In view of that, using numerical simulations, we have developed a compound model incorporating both the principal endogenous and exogenous theories, and investigating their implications for terrestrial planet formation and water-delivery. Comets are also considered in the final analysis, as it is likely that at least some of Earth's water has cometary origin. We analyze our results comparing two different water distribution models, and complement our study using D/H ratio, finding possible relative contributions from each source, focusing on planets formed in the habitable zone. We find that the compound model play an important role by showing more advantage in the amount and time of water-delivery in Earth-like planets.Comment: Accepted for publication in The Astrophysical Journa

Reaction mechanisms for weakly-bound, stable nuclei and unstable, halo nuclei on medium-mass targets

An experimental overview of reactions induced by the stable, but weakly-bound nuclei 6Li, 7Li and 9Be, and by the exotic, halo nuclei 6He, 8B, 11Be and 17F on medium-mass targets, such as 58Ni, 59Co or 64Zn, is presented. Existing data on elastic scattering, total reaction cross sections, fusion processes, breakup and transfer channels are discussed in the framework of a CDCC approach taking into account the breakup degree of freedom.Comment: 7 pages, 6 figures, Invited Talk given by C. Beck to the 10th International Conference on Nucleus-Nucleus Collisions, August 16-21, 2009 Beijing, China; Paper submitted to the NN2009 Proceedings, Nuclear Physics A (to be published

Resposta funcional do parasitoide Coccidoxenoides perminutus (Girault, 1915) em Planococcus citri (Risso, 1813).

Neste trabalho objetivou-se determinar a curva de resposta funcional do parasitoide Coccidoxenoides perminutus sobre P. citri e a taxa de emergência do parasitoide

Performance of intraspecific hybrids (Kouillou x Robusta) of Coffea canephora Pierre.

The experiment was carried out in 2005 in the municipality of Ouro Preto do Oeste at the experimental station of Embrapa Rondônia. 256 genotypes were evaluated, from nine hybridizations among parents of Kouillou (Cpafro 121, Cpafro 194, Cpafro 199 and Emcapa 03) and Robusta (Robusta 1675, Robusta 2258 and Robusta 640). The experimental design was a randomized complete block design, where each cross was represented by a maximum of 32 plants, distributed in four replications. The spacing used was 3.5 x 1.5 m. The average of six harvests and the yield of hulled coffee was 74.90 bags ha-1. Highlight for progeny is Emcapa 03 x Cpafro 194 with average yield of 97.71 bags ha-1. The estimated heritability observed for yield of coffee benefited, was 78.96%. The evaluation of six production seasons was allowed to verify the reliability of the genetic parameters in each set of crops. It was possible to observe that only the evaluation of the 1st and 2nd crops would be enough to estimate the genetic parameters with efficiency, with a coefficient of determination (R2) of 79.10%. With the inclusion of the 3rd crop, R2 estimates rose to 81.10%. The individual evaluations (per plant) carried out in 2006/2007, 2007/2008 and 2008/2009 crops showed the superiority of the plants from crosses 7, 8 and 9. In relation to resistance of orange rust, most of the genotypes were resistant to disease, and 75% of the genotypes did not present any type of infection symptoms. Among the susceptible genotypes, there was a variation between 1 and 15% in the degree of lesion intensity

Parasitismo da cochonilha-farinhenta Planococcus citri (Hemiptera: Pseudococcidae) por Coccidoxenoides perminutus (Hymenoptera: Encyrtidae).

Planococcus citri é uma importante praga da videira, no submédio do Vale do São Francisco, e seu parasitismo por Coccidoxenoides perminutus, de ocorrência natural nesta região, foi estudado por meio da determinação dos parâmetros de resposta funcional. O experimento foi conduzido com ninfas de segundo ínstar dessa cochonilha, ofertadas nas densidades de 2, 4, 8, 14, 28, 40 e 50, empregando discos de folhas de videira (cv. Syrah). Fêmeas recém-emergidas e alimentadas do parasitoide foram confinadas com as ninfas por 24h. A taxa de parasitismo resultou em resposta funcional do tipo III, com os parâmetros tempo de manipulação (Th) e taxa de ataque (a?) de 0,9824h e 0,00718h-1, respectivamente. Observou-se correlação de 94,3% entre o parasitismo observado e o estimado pelo modelo de resposta funcional, com máximo de 27 e 24,44 ninfas parasitadas em 24h, respectivamente. A emergência de parasitoides de ninfas mumificadas variou entre 64 e 95%, em função das densidades estudadas. Os resultados mostraram que a resposta funcional de C. perminutus em ninfas de P. citri é do tipo III e que a taxa de emergência do parasitoide é influenciada pelas diferentes densidades de ninfas de P. citri oferecidas. Com base na resposta funcional determinada, C. perminutus apresenta potencial de controle da praga, contribuindo com informações para um futuro programa de controle biológico

Projectile breakup dynamics for 6^{6}Li + 59^{59}Co: kinematical analysis of α\alpha-dd coincidences

A study of the kinematics of the $\alpha$-$d$ coincidences in the $^{6}$Li + $^{59}$Co system at a bombarding energy of $E_{lab} = 29.6$ MeV is presented. With exclusive measurements performed over different angular intervals it is possible to identify the respective contributions of the sequential projectile breakup and direct projectile breakup components. A careful analysis using a semiclassical approach of these processes provides information on both their lifetime and their distance of occurrence with respect to the target. Breakup to the low-lying (near-threshold) continuum is delayed, and happens at large internuclear distances. This suggests that the influence of the projectile breakup on the complete fusion process can be related essentially to direct breakup to the $^6$Li high-lying continuum spectrum. %Comment: Revised version including new Fig.3 and Fig.4 with new CDCC calculations. Accepted for publication at Eur. Phys. Jour. A. 11 pages, 6 figure