Exact Evolution of the Complete Non-Linear Cosmological Radion
  The cosmological two brane model is discussed in detail. An elegant method for deriving the generalised non-linear equations for the interbrane distance is presented. These equations are used to identify equilibrium positions of the radion, and are then linearised in order to determine the nature of these equilibrium solutions. Numerical methods are then employed to determine the complete behaviour of the (unstabilised) cosmological radion for a variety of interesting cases, including radiation and matter dominated non-Z_2 symmetric branes. The implications to theories involving brane collisions are then discussed. 
Ian R. Vernon, Anne-Christine Davis