Maximal $\nu_\mu - \nu_\tau$ oscillations, the see-saw mechanism and the   Exact Parity Model
  We examine one simple mechanism which leads to approximate maximal $\nu_\mu - \nu_\tau$ oscillations in the standard see-saw model. In particular, we show that this scheme could be implemented in the Exact Parity Model (also known as the mirror matter model). Within this framework the solar neutrino problem is solved by maximal $\nu_e \to \nu'_e$ oscillations (with $\nu'_e$ is the essentially sterile mirror partner of $\nu_e$) and the LSND evidence for $\nu_e \to \nu_\mu$ oscillations can also be explained. 
T. L. Yoon and R. Foot