Radial and vertical diffusion coefficients with respect to Stokes number for runs SI41-3-2-d and SI30-3-2-d. Both D_x and D_z take on similar values as in Fig. 23, where the particle size distribution is shallow (q = 4). The diffusion coefficients corresponding to species that saturate to scale heights similar to the maximum-allowed scale height in the box or do not saturate within the simulation time are indicated with a cross.