Theoretical studies will be conducted on the dynamics of complex nonequilibrium systems with many degrees of freedom focusing on systems which exhibit nontrivial scaling properties. A central aspect of this work involves a general formulation consisting of singular diffusion limits. Issues to be addressed include universality, deterministic versus stochastic dynamics, field theoretic techniques, the role of conservation laws, origins of the separation of time scales, and the breakdown of hydrodynamics in certain systems. Specific applications of these concepts will be applied to problems in seismology, fracture, friction and solid state physics. %%% Research will be conducted on both general concepts and specific applications of self-organized criticality. This is a theory for such common events as avalanches of sandpiles which may have a profound impact on fundamental physics and nonlinear science, and yet may have wide-spread application to a variety of real problems including earthquakes, friction and fracture.