Time-delayed fronts from biased random walks

We generalize a previous model of time-delayed reaction–diffusion fronts (Fort and Méndez 1999 Phys. Rev. Lett. 82 867) to allow for a bias in the microscopic random walk of particles or individuals. We also present a second model which takes the time order of events (diffusion and reproduction) into account. As an example, we apply them to the human invasion front across the USA in the 19th century. The corrections relative to the previous model are substantial. Our results are relevant to physical and biological systems with anisotropic fronts, including particle diffusion in disordered lattices, population invasions, the spread of epidemics, etc

'Les relacions entre la Unió Europea i els països de la conca del Mediterrani' : Barcelona, 24-28 de novembre de 1995

An Alternative Mediterranean Conference under the auspices of several NGOs frorn several countries of the Mediterranean basin was held in Barcelona from 24th to 26th Novernber 1995. Its purpose was to discuss the relationships arnong the European Union and the eastern and southern shore countries in the Mediterranean basin from a non-official point of view, and to evaluate the project of a Euro-Mediterranean Association which was to be launched by the Intergovernmental Euro-Mediterranean Conference at its meeting in Barcelona on 27th and 28th November. This Serninar was the focus of most discussion at the Alternative Mediterranean Conference

Viatge al Marroc de la Secció de Geografia de la Universitat de Girona, 24-30 d'abril de 2000

A group of teachers and students of the Geography Unit of the University of Girona conducted a field trip in a part of Northern Morocco, which once belonged to the Spanish Protectorate. The visit took place between 24th and 30th April 2000. Some teachers of the University of Tetouan accompanied the group and offered comprehensive geographical explanations of the area, including physical, social and economic aspects