15,318 research outputs found
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
Remarks on supersymmetry of quantum systems with position-dependent effective masses
We apply the supersymmetry approach to one-dimensional quantum systems with
spatially-dependent mass, by including their ordering ambiguities dependence.
In this way we extend the results recently reported in the literature.
Furthermore, we point out a connection between these systems and others with
constant masses. This is done through convenient transformations in the
coordinates and wavefunctions.Comment: 8 pages, 1 figur
Scaling in a continuous time model for biological aging
In this paper we consider a generalization to the asexual version of the
Penna model for biological aging, where we take a continuous time limit. The
genotype associated to each individual is an interval of real numbers over
which Dirac --functions are defined, representing genetically
programmed diseases to be switched on at defined ages of the individual life.
We discuss two different continuous limits for the evolution equation and two
different mutation protocols, to be implemented during reproduction. Exact
stationary solutions are obtained and scaling properties are discussed.Comment: 10 pages, 6 figure
Sherrington-Kirkpatrick model near : expanding around the Replica Symmetric Solution
An expansion for the free energy functional of the Sherrington-Kirkpatrick
(SK) model, around the Replica Symmetric SK solution is investigated. In particular, when the
expansion is truncated to fourth order in. . The
Full Replica Symmetry Broken (FRSB) solution is explicitly found but it turns
out to exist only in the range of temperature , not
including T=0. On the other hand an expansion around the paramagnetic solution
up to fourth order yields a FRSB solution
that exists in a limited temperature range .Comment: 18 pages, 3 figure
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