  Let $M$ be a compact Riemannian manifold and $h$ a smooth function on $M$.
Let $\rho^h(x)=\inf_{|v|=1}\left(Ric_x(v,v)-2Hess(h)_x(v,v) \right)$. Here
$Ric_x$ denotes the Ricci curvature at $x$ and $Hess(h)$ is the Hessian of $h$.
Then $M$ has finite fundamental group if $\Delta ^h-\rho^h<0$. Here $\Delta
^h=: \Delta +2L_{\nabla h}$ is the Bismut-Witten Laplacian. This leads to a
quick proof of recent results on extension of Myers' theorem to manifolds with
mostly positive curvature. There is also a similar result for noncompact
manifolds.
