Probe brane dynamics on cosmological brane backgrounds
  We consider the dynamics of a single probe brane on various cosmological brane backgrounds. The on-shell condition of the static probe brane leads to the supersymmetric intersection rules for static BPS configurations, though the cosmological backgrounds do not preserve any supersymmetries. This is a remarkable feature associated with the cosmological backgrounds because in the static background the on-shell condition of the static brane gives no constraint on the brane configuration. Furthermore, it follows that under this condition there is no velocity-independent force for the probe brane even on the cosmological backgrounds. 
Kunihito Uzawa, Kentaroh Yoshida
hep-th gr-qc