Before revision:  A theoretical analysis of the phase boundaries shows that the critical force for rupture scales as \left(\log C_{\textrm{m}}\right)^{\alpha} with \alpha=1\,(0.5) for \textrm{ U-I ( \textrm{  \textrm{ I-F } \textrm{ ) transition.
After revision:  A theoretical analysis of the phase boundaries shows that the critical force for rupture scales as \left(\log C_{\textrm{m}}\right)^{\alpha} with \alpha=1\,(0.5) for \textrm{ U-I ( \textrm{ \textrm{ I-F } \textrm{F ) transition.