Elastic free energy landscapes of the tumor-gel system.

The landscapes are plotted versus the tumor's ellipsoidal axes ratios and . The origin has been shifted, so that the maximum energy is zero in each case: (a) For . The oblate shapes ( = = 3) are the low energy states. This surface has been generated from 576 separate nonlinear elasticity computations of tumors of aspect ratios and varying between 1 and 3, growing in a gel. (b) The same as (a), but for . Note the flatness of the landscape relative to (a). Spherical shapes are not penalized strongly for , but are strongly penalized for .