Margulis Numbers for Haken Manifolds

For every closed orientable hyperbolic Haken 3-manifold and, more generally, for any orientable hyperbolic 3-manifold M which is homeomorphic to the interior of a Haken manifold, the number 0:286 is a Margulis number. If H1(M;Q) 6= 0, or if M is closed and contains a semi- ber, then 0:292 is a Margulis number for M.