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We introduce a simple model of population dynamics which considers reproducing individuals or particles with birth and death rates depending on the number of other individuals in their neighborhood. The model shows an inhomogeneous quasistationary pattern with many different clusters of particles arranged periodically in space. We derive the equation for(More)
We present properties of Lotka-Volterra equations describing ecological competition among a large number of interacting species. First we extend previous stability conditions to the case of a non-homogeneous niche space, i.e. that of a carrying capacity depending on the species trait. Second, we discuss mechanisms leading to species clustering and obtain an(More)
Population dynamics of individuals undergoing birth and death and diffusing by short- or long-range two-dimensional spatial excursions (Gaussian jumps or Lévy flights) is studied. Competitive interactions are considered in a global case, in which birth and death rates are influenced by all individuals in the system, and in a nonlocal but finite-range case(More)
We study the properties of general Lotka-Volterra models with competitive interactions. The intensity of the competition depends on the position of species in an abstract niche space through an interaction kernel. We show analytically and numerically that the properties of these models change dramatically when the Fourier transform of this kernel is not(More)
The increasing use of Geographic Information System applications has generated a strong interest in the assessment of data quality. As an example of quantitative raster data, we analyzed errors in Digital Terrain Models (DTM). Errors might be classified as systematic (strongly dependent on the production methodology) and random. The present work attempts to(More)
The dynamics of coherent structures present in real-world environmental data is analyzed. The method developed in this Paper combines the power of the Proper Orthogonal Decomposition (POD) technique to identify these coherent structures in experimental data sets, and its optimality in providing Galerkin basis for projecting and reducing complex dynamical(More)
We propose a nonlinear ocean forecasting technique based on a combination of genetic algorithms and empirical orthogonal function (EOF) analysis. The method is used to forecast the space-time variability of the sea surface temperature (SST) in the Alboran Sea. The genetic algorithm finds the equations that best describe the behaviour of the different(More)
In this paper, an ongoing experimental project relating distance education and interactive digital TV is presented. In last years, a lot of expectations and problems have risen around both fields separately and, in this project, we explore synergies that will provide mutual advantages: a wider market for distance learning and a value-added application for(More)
  • F D 'ovidio, Jordi Isern-Fontanet, Cristóbal López, Emilio Hernández-García, Emilio García-Ladona
  • 2008
Transport and mixing properties of surface currents can be detected from altimet-ric data by both Eulerian and Lagrangian diagnostics. In contrast with Eulerian diagnostics, Lagrangian tools like the local Lyapunov exponents have the advantage of exploiting both spatial and temporal variability of the velocity field and are in principle able to unveil(More)
The problem of minimizing the cost functional of an Optimal Control System through the use of constrained Variational Calculus is a generalization of the geodetic problem in Riemannian geometry. In the framework of a geometric formulation of Optimal Control, we define a metric structure associated to the Optimal Control System on the enlarged space of state(More)