Nontrivial temporal scaling in a Galilean stick-slip dynamics

We examine the stick-slip fluctuating response of a rough massive non-rotating cylinder moving on a rough inclined groove which is submitted to weak external perturbations and which is maintained well below the angle of repose. The experiments presented here, which are reminiscent of the Galileo's works with rolling objects on inclines, have brought in the last years important new insights into the friction between surfaces in relative motion and are of relevance for earthquakes, differing from classical block-spring models by the mechanism of energy input in the system. Robust nontrivial temporal scaling laws appearing in the dynamics of this system are reported, and it is shown that the time-support where dissipation occurs approaches a statistical fractal set with a fixed value of dimension. The distribution of periods of inactivity in the intermittent motion of the cylinder is also studied and found to be closely related to the lacunarity of a random version of the classic triadic Cantor set on the line.Comment: 7 pages including 6 figure

Extremely Metal-Poor Galaxies: The HI Content

Extremely metal-poor (XMP) galaxies are chemically, and possibly dynamically, primordial objects in the local Universe. Our objective is to characterize the HI content of the XMP galaxies as a class, using as a reference the list of 140 known local XMPs compiled by Morales-Luis et al. (2011). We have observed 29 XMPs, which had not been observed before at 21 cm, using the Effelsberg radio telescope. This information was complemented with HI data published in literature for a further 53 XMPs. In addition, optical data from the literature provided morphologies, stellar masses, star-formation rates and metallicities. Effelsberg HI integrated flux densities are between 1 and 15 Jy km/s, while line widths are between 20 and 120 km/s. HI integrated flux densities and line widths from literature are in the range 0.1 - 200 Jy km/s and 15 - 150 km/s, respectively. Of the 10 new Effelsberg detections, two sources show an asymmetric double-horn profile, while the remaining sources show either asymmetric (7 sources) or symmetric (1 source) single-peak 21 cm line profiles. An asymmetry in the HI line profile is systematically accompanied by an asymmetry in the optical morphology. Typically, the g-band stellar mass-to-light ratios are ~0.1, whereas the HI gas mass-to-light ratios may be up to 2 orders of magnitude larger. Moreover, HI gas-to-stellar mass ratios fall typically between 10 and 20, denoting that XMPs are extremely gas-rich. We find an anti-correlation between the HI gas mass-to-light ratio and the luminosity, whereby fainter XMPs are more gas-rich than brighter XMPs, suggesting that brighter sources have converted a larger fraction of their HI gas into stars. The dynamical masses inferred from the HI line widths imply that the stellar mass does not exceed 5% of the dynamical mass, while the \ion{H}{i} mass constitutes between 20 and 60% of the dynamical mass. (abridged)Comment: 30 pages, accepted for A&

Base de dados geoespaciais do projeto Geosaltus.

Este trabalho objetiva apresentar a primeira versão da base de dados geoespaciais (BDG) do Projeto GeoSaltus (Classificação e Espacialização do Estoque de Carbono de Florestas Naturais e Plantadas por meio de Sensoriamento Remoto). Os sistemas florestais fazem parte de uma importante estratégia de uso da terra, voltada à manutenção da biodiversidade, aos serviços ambientais, à geração de produtos madeireiros e não madeireiros. Os fluxos de emissões de gases de efeito estufa e o carbono estocado nas florestas são informações imprescindíveis, e sua estimativa pode amparar políticas públicas de desenvolvimento e sustentabilidade. Esta base objetiva integrar dados geoespaciais provenientes de várias fontes e que permitam gerar informações e consultas entre os membros do projeto e demais usuários. Os diferentes planos de informações geográficas usados na geração da BDG foram definidos a partir de sua relevância para o desenvolvimento do projeto e foram divididos em: a) imagens de satélite/bases cartográficas, b) mapas temáticos e c) áreas de estudo. A consulta da BDG e de suas relações espaciais pode ser acessada por meio do webgis GeoSaltus (http://mapas.cnpm.embrapa.br/geosaltus/)

Exigência de fósforo disponível para frangos de corte nas fases de crescimento e terminação.

bitstream/item/58575/1/CUsersPiazzonDocuments211.pd

Solubility isotope effects in aqueous solutions of methane

The isotope effect on the Henry's law coefficients of methane in aqueous solution (H/D and C-12/C-13 substitution) are interpreted using the statistical mechanical theory of condensed phase isotope effects. The missing spectroscopic data needed for the implementation of the theory were obtained either experimentally (infrared measurements), by computer simulation (molecular dynamics technique), or estimated using the Wilson's GF matrix method. The order of magnitude and sign of both solute isotope effects can be predicted by the theory. Even a crude estimation based on data from previous vapor pressure isotope effect studies of pure methane at low temperature can explain the inverse effect found for the solubility of deuterated methane in water. (C) 2002 American Institute of Physics

Comportamento de genótipos de canola em Maringá em 2003.

bitstream/CNPT-2010/40480/1/p-co115.pd