Tapio P. Simula

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This paper concerns the propagation of particles through a quenched random medium. In the one-and two-dimensional models considered, the local dynamics is given by expanding circle maps and hyperbolic toral automorphisms, respectively. The particle motion in both models is chaotic and found to fluctuate about a linear drift. In the proper scaling limit, the(More)
We have studied a model of a random walk in a quenched random environment. In addition to featuring anomalous diffusion and localization, for special regimes of disorder parameters the particle density decomposes into multi-Gaussian structure while its cumulative distribution is normal. We explain the observed fine structure of the density and point out its(More)
The formation of quantized vortices in trapped, gaseous Bose-Einstein con-densates is considered. The thermodynamic stability of vortex states and the essential role of the surface excitations as a route for vortex penetration into the condensate are discussed. Special focus is on finite-temperature effects of the vortex nucleation process. It is concluded(More)
Teknillinen korkeakoulu Teknillisen fysiikan ja matematiikan osasto Materiaalifysiikan laboratorio Dissertation for the degree of Doctor of Technology to be presented with due permission for public examination and debate in Auditorium F1 at Helsinki University of Technology (Espoo, Finland) on the 10 th of January, 2003, at 12 o'clock noon. ABSTRACT OF(More)
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