Abstract
A model incorporating three left-handed SU(2)L×U(1)Y doublet neutrinos and three right-handed singlet neutrinos, with leptonic Dirac mass submatrices similar to empirical forms which work well for quarks, is required to yield both the nonadiabatic Mikheyev-Smirnov-Wolfenstein solar neutrino effect and the depleted flux of atmospheric muon neutrinos observed by Kamiokande. We find a small segment of the δm232 vs sin22θ23 plane exists where such solutions can be achieved and identify the class of right-handed Majorana submatrices required.