In the next three plots we report contour plots of \sigma computed at t=0.98, 1,97, and 2.96 Myr.  The values of \sigma have been smoothed with a median filter (see previous section).
 
 

In the next two plots we report the particles fate and a contour plot of the value of \Beta, which is the exponent in the relation:

The value of \Beta has been computed by minimizing the value of \Chi^2 (usual procedure for linear regression, see Numerical Recipes, pp. 655-660).
 

Comments and suggestions.