  The shear flow is modeled in terms of local structural rearrangements. Most
of these rearrangements are strongly asymmetric, because the embedding matrix
tends to be elastically adapted to the initial state and to have a marked
elastic misfit with regard to the final state. As one approaches the Maxwell
time, the asymmetry becomes time-dependent, thus enabling the system to leave
the initial state. The model explains the Kohlrausch behavior at the main peak
in terms of the interaction between different local structural rearrangements.
