I was at a math seminar, discussing the Boltzman mass transport equation. There was a scaling factor, as a parameter, which varied 0...1, and the speaker said "a = 1, is the kinetic regime, while a = 0 is the diffusion regime." What does that mean? The point was to characterize the transition region in between.
Later, someone asked about "isotropizing vs. thermalizing" (or something like that). ??