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| Author(s): |
Javier Eduardo Satulovsky
Total Authors: 1
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| Document type: | Doctoral Thesis |
| Press: | São Paulo. |
| Institution: | Universidade de São Paulo (USP). Instituto de Física (IF/SBI) |
| Defense date: | 1995-12-19 |
| Examining board members: |
Tania Tome Martins de Castro;
Paulo Mascarello Bisch;
Jose Roberto Drugowich de Felicio;
Vera Bohomoletz Henriques;
Nelson Ithiro Tanaka
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| Advisor: | Tania Tome Martins de Castro |
| Abstract | |
In this work, we introduce and study a stochastic lattice gas model for the evolution of an interacting particle system describing two species: prey and predators. Prey undergo autocatalytic reproduction on empty sites of a lattice. Predators also reproduce autocatalytically at the expense of prey, as well as suffer spontaneous annihilations. The irreversible local rules of the model, involving two parameters, are inspired both in the Lotka-Volterra model and the contact process. In the stationary regime, the model shows three phases. The first one is associated to an absorbing state in which the lattice is completely covered by prey. The second one is characterized by finite values of the density of each species. As we tune the parameters values inside that phase, local oscillations in the population densities start to appear. The second phase is reached from the first one through a line of continuous kinetic phase transitions. The line belongs to the universality class of directed percolation in d+1 dimensions, except for its terminal point, which belongs to the universality class of ordinary percolation. The third phase corresponds to another absorbing state completely devoided of particles. The transition from the second to the third phase is continuous and also belongs to universality class of directed percolation in d+1 dimensions. The model has been studied by means of computer simulations as well as by using approximate analytical technics. (AU) | |