Four-dimensional gravity on supersymmetric dilatonic domain walls

We investigate the localization of four-dimensional metastable gravity in supersymmetric dilatonic domain walls through massive modes by considering several scenarios in the model. We compute corrections to the Newtonian potential for small and long distances compared with a crossover scale given in terms of the dilatonic coupling. 4D gravity behavior is developed on the brane for distance very much below the crossover scale, while for distance much larger, the 5D gravity is recovered. Whereas in the former regime gravity is always attractive, in the latter regime due to non-normalizable unstable massive graviton modes present on the spectrum, in some special cases, gravity appears to be repulsive and signalizes a gravitational confining phase which is able to produce an inflationary phase of the Universe.Comment: 11 pages, 4 figures, Latex. Version to appear in PL

A global simulation for laser driven MeV electrons in 50μm50\mu m-diameter fast ignition targets

The results from 2.5-dimensional Particle-in-Cell simulations for the interaction of a picosecond-long ignition laser pulse with a plasma pellet of 50-$\mu m$ diameter and 40 critical density are presented. The high density pellet is surrounded by an underdense corona and is isolated by a vacuum region from the simulation box boundary. The laser pulse is shown to filament and create density channels on the laser-plasma interface. The density channels increase the laser absorption efficiency and help generate an energetic electron distribution with a large angular spread. The combined distribution of the forward-going energetic electrons and the induced return electrons is marginally unstable to the current filament instability. The ions play an important role in neutralizing the space charges induced by the the temperature disparity between different electron groups. No global coalescing of the current filaments resulted from the instability is observed, consistent with the observed large angular spread of the energetic electrons.Comment: 9 pages, 6 figures, to appear in Physics of Plasmas (May 2006

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

Uso de Geotecnologias na detecção de potenciais Áreas de Preservação Permanente e Reserva Legal na Região Administrativa Central do Estado de São Paulo.

Our objective in this work was to estimate, using geoprocessing techniques, the amount of permanent preservation areas (APPs) at the rural areas of the cities that are part of the Central Administrative Region of the State of São Paulo in the year 2016, to verify its adequacy to the New Brazilian Forest Code and to estimate, by means of land use and cover classification, the environmental liabilities for legal reserve (RL) areas in the region's cities. We additionally detected sugarcane crops in terrains with slope degrees higher than 12% and which will no longer be used for crops, in accordance with law decree 47.700/SP, and may therefore indicate areas which are viable for use as RLs, thus helping reduce the region's environmental liabilities. Our results show that the region contains 30.492,6 ha of environmental liabilities in APP areas and 27,493.6 ha in RL areas. Current sugarcane areas with potential to become RLs comprise 35,630.6 ha. The APP and RL areas are unevenly distributed across the region. Some cities showed no environmental liabilities, whereas others could reconcile or reduce theirs by 14.5% to 79.5% by using the areas that will no longer be used for sugarcane crops

Expansão da cafeicultura na porção leste do estado de São Paulo.

Our aim in this work was to map the main land-use and land-cover changes at 25 cities located at the watersheds of the Mogi-Guaçu and Pardo rivers over the last 27 years. We focused on coffee and sugarcane crops at these region, known as Mogiana Paulista. We updated the sugarcane crop areas to the year 2015 using maps produced by the Canasat project. For land-use and land-cover classification of these 25 cities in 2015 we used a Google Earth image file in a GIS environment. The method we used was on-screen visual image interpretation of high-spatial-resolution images, which were later compared to data from 1988. Along the 27- year period, coffee crops expanded approximately 80%, from 67.3 thousand to 123.8 thousand hectares. The 25 cities which are the main coffee producers at Mogiana Paulista showed concentration of coffee crops, which make up a total of approximately 111 thousand hectares. Both coffee and sugarcane may still advance onto parts of these cities' areas that are currently used as pastures, which the land-cover that loses more areas. Pastures still occupy 322 thousand hectares, or about 30% of the area of these 25 cities, and 252 thousand of these hectares feature slope degrees which are adequate for the mechanized harvesting of both sugarcane and coffee