The curious observation has been made in optimised shear plasmas in JET that whilst both density and temperature profiles have a transition from a steep gradient region to a shallow gradient region, these generally occur at a different spatial location. This surprising result is shown to be consistent with the particle and thermal diffusivities falling in the same region of the plasma, if a particle pinch term which is proportional to the particle diffusivity is included. It is shown that such a pinch velocity is a natural feature of a random walk diffusion of particles and will be significant in other areas, particularly in the edge of H-mode plasmas.