Unravelling Temporal Variability in Saturn's Spiral Density Waves:   Results and Predictions
  We describe a model that accounts for the complex morphology of spiral density waves raised in Saturn's rings by the co-orbital satellites, Janus and Epimetheus. Our model may be corroborated by future Cassini observations of these time-variable wave patterns. 
Matthew S. Tiscareno, Philip D. Nicholson, Joseph A. Burns, Matthew M.   Hedman, Carolyn C. Porco