Aspectos econômicos da comercialização de milho pipoca, 1981-90.

Os objetivos deste estudo sao verificar a existencia de padroes sazonais de precos e quantidades comercializadas de milho pipoca nos mercados atacadistas dos Estados de Minas Gerais, Sao Paulo e Rio Grande do Sul e levantar informacoes sobre as regioes produtoras. A analise estatistica dos dados das centrais de abastecimento destes estados mostra a existencia de padrao sazonal de quantidades para os tres mercados e de precos apenas para Sao Paulo. Um dos motivos deste fato e a demanda estar fortemente concentrada na epoca proxima a colheita, o que impede a variacao dos precos para baixo na safra e para cima na entressafra. Os dados sobre as regioes produtores de milho pipoca sugerem a existencia de integracao entre os mercados de Minas Gerais e Rio Grande com o de Sao Paulo

Empiricism and stochastics in cellular automaton modeling of urban land use dynamics

An increasing number of models for predicting land use change in regions of rapidurbanization are being proposed and built using ideas from cellular automata (CA)theory. Calibrating such models to real situations is highly problematic and to date,serious attention has not been focused on the estimation problem. In this paper, wepropose a structure for simulating urban change based on estimating land usetransitions using elementary probabilistic methods which draw their inspiration fromBayes' theory and the related ?weights of evidence? approach. These land use changeprobabilities drive a CA model ? DINAMICA ? conceived at the Center for RemoteSensing of the Federal University of Minas Gerais (CSR-UFMG). This is based on aneight cell Moore neighborhood approach implemented through empirical land useallocation algorithms. The model framework has been applied to a medium-size townin the west of São Paulo State, Bauru. We show how various socio-economic andinfrastructural factors can be combined using the weights of evidence approach whichenables us to predict the probability of changes between land use types in differentcells of the system. Different predictions for the town during the period 1979-1988were generated, and statistical validation was then conducted using a multipleresolution fitting procedure. These modeling experiments support the essential logicof adopting Bayesian empirical methods which synthesize various information aboutspatial infrastructure as the driver of urban land use change. This indicates therelevance of the approach for generating forecasts of growth for Brazilian citiesparticularly and for world-wide cities in general

Molecular Line Profile Fitting with Analytic Radiative Transfer Models

We present a study of analytic models of starless cores whose line profiles have ``infall asymmetry,'' or blue-skewed shapes indicative of contracting motions. We compare the ability of two types of analytical radiative transfer models to reproduce the line profiles and infall speeds of centrally condensed starless cores whose infall speeds are spatially constant and range between 0 and 0.2 km s-1. The model line profiles of HCO+ (J=1-0) and HCO+ (J=3-2) are produced by a self-consistent Monte Carlo radiative transfer code. The analytic models assume that the excitation temperature in the front of the cloud is either constant (``two-layer'' model) or increases inward as a linear function of optical depth (``hill'' model). Each analytic model is matched to the line profile by rapid least-squares fitting. The blue-asymmetric line profiles with two peaks, or with a blue shifted peak and a red shifted shoulder, can be well fit by the ``HILL5'' model (a five parameter version of the hill model), with an RMS error of 0.02 km s-1. A peak signal to noise ratio of at least 30 in the molecular line observations is required for performing these analytic radiative transfer fits to the line profiles.Comment: 48 pages, 20 figures, accepted for publication in Ap

Estudo sobre a viabilidade de remediação de pesticidas por ectomicorrizas e avaliação da sua tolerância em exposição ao glifosato.

Os fungos ectomicorrízicos (ECM) têm sido utilizados na produção de mudas florestais de qualidade. Neste trabalho, levantou-se a hipótese de que estes microrganismos também auxiliariam na degradação de moléculas orgânicas de pesticidas (xenobiontes) registrados no setor florestal. Este trabalho teve como objetivo avaliar a tolerância de fungo ectomicorrízico em exposição ao herbicida glifosato. O xenobionte atrasou o desenvolvimento do fungo ECM-Un01, no entanto a dose testada não foi suficiente para impedir seu desenvolvimento posterior. Existem, portanto, indícios do isolado ECM-Un01 ser tolerante ao glifosato, na dose utilizada.Resumo expandido