Benchmark calculation of p-3H and n-3He scattering

p-3H and n-3He scattering in the energy range above the n-3He but below the d-d thresholds is studied by solving the 4-nucleon problem with a realistic nucleon-nucleon interaction. Three different methods -- Alt, Grassberger and Sandhas, Hyperspherical Harmonics, and Faddeev-Yakubovsky -- have been employed and their results for both elastic and charge-exchange processes are compared. We observe a good agreement between the three different methods, thus the obtained results may serve as a benchmark. A comparison with the available experimental data is also reported and discussed.Comment: 13 pages, 6 figures. arXiv admin note: text overlap with arXiv:1109.362

Photodisintegration of the triton with realistic potentials

The process $\gamma + t \to n + d$ is treated by means of three-body integral equations employing in their kernel the W-Matrix representation of the subsystem amplitudes. As compared to the plane wave (Born) approximation the full solution of the integral equations, which takes into account the final state interaction, shows at low energies a 24% enhancement. The calculations are based on the semirealistic Malfliet-Tjon and the realistic Paris and Bonn B potentials. For comparison with earlier calculations we also present results for the Yamaguchi potential. In the low-energy region a remarkable potential dependence is observed, which vanishes at higher energies.Comment: 16 pages REVTeX, 8 postscript figures included, uses epsfig.st

Teor e acúmulo de nutrientes por plantas de feijão caupi em função do fósforo e da saturação por bases.

O feijão caupi (Vigna unguiculata L., Walp) é utilizado como uma das principais fontes proteicas da população rural na região Amazônica e da região Nordeste. O crescimento, a produtividade e o estado nutricional do feijão caupi são afetados por um grande número de fatores, destacando-se a acidez do solo e baixa disponibilidade de fósforo (P). Por outro lado, há escassez de informações sobre a nutrição mineral do feijão caupi, em relação a teores e acúmulos foliares e nos grãos. Neste contexto, o objetivo do trabalho foi avaliar o efeito da saturação por bases e da adubação fosfatada sobre os teores e acúmulos de macro e micronutrientes, na massa seca da parte aérea e nos grãos de feijão caupi. O delineamento experimental foi de blocos casualizados, em esquema fatorial 4 x 2, sendo quatro doses de P (0, 25, 50 e 100 kg ha-1 de P2O5) e duassaturações por bases (50 e 60%), com oito repetições. Os teores e acúmulos de macronutrientes do feijão caupi foram influenciados pelas doses de P e pela saturação por bases. Os maiores teores e acúmulos, de uma maneira geral, ocorreram na saturação por base de 60%. A planta de feijão caupi acumulou macronutrientes na seguinte ordem: N>K>Ca>Mg>P, enquanto os micronutrientes seguiram a ordem Fe>B>Mn>Zn>Cu. O N e o P são os nutrientes exportados em maior quantidade pelos grãos, em relação à quantidade acumulada na matéria seca da parte aérea

Multiple scattering effects in quasi free scattering from halo nuclei: a test to Distorted Wave Impulse Approximation

Full Faddeev-type calculations are performed for $^{11}$Be breakup on proton target at 38.4, 100, and 200 MeV/u incident energies. The convergence of the multiple scattering expansion is investigated. The results are compared with those of other frameworks like Distorted Wave Impulse Approximation that are based on an incomplete and truncated multiple scattering expansion.Comment: 7 pages, 16 figures, to be published in Phys. Rev.

Laser-driven shock acceleration of monoenergetic ion beams

We show that monoenergetic ion beams can be accelerated by moderate Mach number collisionless, electrostatic shocks propagating in a long scale-length exponentially decaying plasma profile. Strong plasma heating and density steepening produced by an intense laser pulse near the critical density can launch such shocks that propagate in the extended plasma at high velocities. The generation of a monoenergetic ion beam is possible due to the small and constant sheath electric field associated with the slowly decreasing density profile. The conditions for the acceleration of high-quality, energetic ion beams are identified through theory and multidimensional particle-in-cell simulations. The scaling of the ion energy with laser intensity shows that it is possible to generate $\sim 200$ MeV proton beams with state-of-the-art 100 TW class laser systems.Comment: 13 pages, 4 figures, accepted for publication in Physical Review Letter

An intact signal peptide on dengue virus E protein enhances immunogenicity for CD8+ T cells and antibody when expressed from modified vaccinia Ankara

Dengue is a global public health concern and this is aggravated by a lack of vaccines or antiviral therapies. Despite the well-known role of CD8(+) T cells in the immunopathogenesis of Dengue virus (DENV), only recent studies have highlighted the importance of this arm of the immune response in protection against the disease. Thus, the majority of DENV vaccine candidates are designed to achieve protective titers of neutralizing antibodies, with less regard for cellular responses. Here, we used a mouse model to investigate CD8(+) T cell and humoral responses to a set of potential DENV vaccines based on recombinant modified vaccinia virus Ankara (rMVA). To enable this study, we identified two CD8(+) T cell epitopes in the DENV-3 E protein in C57BL/6 mice. Using these we found that all the rMVA vaccines elicited DENV-specific CD8(+) T cells that were cytotoxic in vivo and polyfunctional in vitro. Moreover, vaccines expressing the E protein with an intact signal peptide sequence elicited more DENV-specific CD8(+) T cells than those expressing E proteins in the cytoplasm. Significantly, it was these same ER-targeted E protein vaccines that elicited antibody responses. Our results support the further development of rMVA vaccines expressing DENV E proteins and add to the tools available for dengue vaccine development.Parts of this work were supported by the InstitutoNacional de Ciência e Tecnologia de Vacinas–INCTV (National Insti-tute of Science and Technology of Vaccines) and by a FAPEMIGPPM grant (CBB, PPM-00461-11). BRQ was a CAPES/PDSE fellow-ship recipient (8815-11-9). FGF is a CNPq fellowship recipient. DCTis an ARC Future Fellow (FT110100310)

Ion acceleration from laser-driven electrostatic shocks

Multi-dimensional particle-in-cell simulations are used to study the generation of electrostatic shocks in plasma and the reflection of background ions to produce high-quality and high-energy ion beams. Electrostatic shocks are driven by the interaction of two plasmas with different density and/or relative drift velocity. The energy and number of ions reflected by the shock increase with increasing density ratio and relative drift velocity between the two interacting plasmas. It is shown that the interaction of intense lasers with tailored near-critical density plasmas allows for the efficient heating of the plasma electrons and steepening of the plasma profile at the critical density interface, leading to the generation of high-velocity shock structures and high-energy ion beams. Our results indicate that high-quality 200 MeV shock-accelerated ion beams required for medical applications may be obtained with current laser systems.Comment: 33 pages, 12 figures, accepted for publication in Physics of Plasma