AbstractWe present a calculation of the temperature dependence of the diffusion coefficient in a unidimensional Heisenberg alternating model. We compare it - with qualitative agreement - to NMR results on K-TCNQ.
AbstractWe study a stochastic model for 2-d incompressible fluids. We show that the kinetic equation governing the evolution of the velocity correlation function has a remarkable property which suggests that a regime of time and wave number exists over which self-consistent transport modes are exponentially decaying. The characteristic time of this regime is shorter than the characteristic time of classical hydrodynamics: it is defined by the limit k β 0, t β β and k2βIn(1/k)t finite.