Stablizing oscillating universes against quantum decay
  We investigate the effect of vacuum corrections, due to the trace anomaly and Casimir effect, on the stability of an oscillating universe with respect to decay by tunneling to the singularity. We find that these corrections do not generally stabilize an oscillating universe. However, stability may be achieved for some specially fine-tuned non-vacuum states. 
Audrey T. Mithani and Alexander Vilenkin
hep-th gr-qc