An alternative theoretical approach to describe planetary systems through a Schrodinger-type diffusion equation

In the present work we show that planetary mean distances can be calculated with the help of a Schrodinger-type diffusion equation. The obtained results are shown to agree with the observed orbits of all the planets and of the asteroid belt in the solar system, with only three empty states. Furthermore, the equation solutions predict a fundamental orbit at 0.05 AU from solar-type stars, a result confirmed by recent discoveries. In contrast to other similar approaches previously presented in the literature, we take into account the flatness of the solar system, by considering the flat solutions of the Schrodinger-type equation. The model has just one input parameter, given by the mean distance of Mercury.Comment: 6 pages. Version accepted for publication in Chaos, Solitons & Fractal

Qualidade de sementes forrageiras de clima temperado.

Atual contexto do setor produtivo; Prejuízos decorrentes da baixa qualidade de sementes; Atributos da qualidade de sementes forrageiras.bitstream/item/61500/1/DT-119.pd

Diffusive epidemic process: theory and simulation

We study the continuous absorbing-state phase transition in the one-dimensional diffusive epidemic process via mean-field theory and Monte Carlo simulation. In this model, particles of two species (A and B) hop on a lattice and undergo reactions B -> A and A + B -> 2B; the total particle number is conserved. We formulate the model as a continuous-time Markov process described by a master equation. A phase transition between the (absorbing) B-free state and an active state is observed as the parameters (reaction and diffusion rates, and total particle density) are varied. Mean-field theory reveals a surprising, nonmonotonic dependence of the critical recovery rate on the diffusion rate of B particles. A computational realization of the process that is faithful to the transition rates defining the model is devised, allowing for direct comparison with theory. Using the quasi-stationary simulation method we determine the order parameter and the survival time in systems of up to 4000 sites. Due to strong finite-size effects, the results converge only for large system sizes. We find no evidence for a discontinuous transition. Our results are consistent with the existence of three distinct universality classes, depending on whether A particles diffusive more rapidly, less rapidly, or at the same rate as B particles.Comment: 19 pages, 5 figure

Particle Creation by a Moving Boundary with Robin Boundary Condition

We consider a massless scalar field in 1+1 dimensions satisfying a Robin boundary condition (BC) at a non-relativistic moving boundary. We derive a Bogoliubov transformation between input and output bosonic field operators, which allows us to calculate the spectral distribution of created particles. The cases of Dirichlet and Neumann BC may be obtained from our result as limiting cases. These two limits yield the same spectrum, which turns out to be an upper bound for the spectra derived for Robin BC. We show that the particle emission effect can be considerably reduced (with respect to the Dirichlet/Neumann case) by selecting a particular value for the oscillation frequency of the boundary position

Oscillatory behavior of light in the composite Goos-Hanchen shift

Sem informaçãoFor incidence in the critical region, the propagation of Gaussian lasers through dielectric blocks is characterized by the joint action of angular deviations and lateral displacements. This mixed effect, known as the composite Goos-Hanchen shift, produces a lateral displacement that is dependent on the axial coordinate, recently confirmed by a weak measurement experiment. We discuss under which conditions this axial lateral displacement, which only exists for the composite Goos-Hanchen shift, presents an oscillatory behavior. This oscillation phenomenon shows a peculiar behavior of light for critical incidence and, if experimentally tested, could stimulate further theoretical studies and lead to interesting optical applications.95519Sem informaçãoSem informaçãoSem informaçã

Metodologia para avaliação de impactos de mudanças climáticas na demanda de água para a agricultura irrigada em nível de bacia hidrográfica.

Propomos uma metodologia para avaliação de impactos das mudanças climáticas na demanda de água para irrigação em nível de bacia hidrográfica, utilizando integração de modelos, na Bacia do Jaguaribe, no Estado do Ceará. Foi empregado o sistema integrado de modelagem regional Providing Regional Climates for Impact Studies (Precis), submetido ao método de redução de escala dinâmica, utilizando-se o modelo climático regional HadRM3P com as condições de contorno do modelo global HadAM3P, do Hadley Centre. Foi utilizado um conjunto de climatologia de base do modelo de 1961 a 1990 e de projeções climáticas futuras (2040) com resolução de 0,44º x 0,44º. As coordenadas geográficas da região em estudo foram consideradas para interpolação, num sistema de informação geográfica abrangendo área de 6.415,10km2. A evapotranspiração de referência foi estimada pelo método simplificado de Penman-Monteith FAO, utilizando-se dados mínimos. O aumento da necessidade hídrica bruta média foi estimado em 33,62% e 37,87% respectivamente para o ano de 2040, conforme o cenário analisado (A2 e B2).Editores técnicos: Maria Fernanda Moura, Giampaolo Queiroz Pellegrino, Lineu Neiva Rodrigues