So it's a mixed practice or nothing then and that probably means NHS dentistry will not be the same again.

BBC: A toothy smile

But buybacks have a more mixed assessment in practice ( here, here) and are typically only a smart if a company is (a) under-valued and (b) has no better uses of capital.

FORBES: Connect

With his aura of invincibility fading and lacking match practice, results were mixed but he did reach the semifinals of the U.S. Open before losing to eventual winner Juan Martin Del Potro.

CNN: Nadal vows to claim fifth French Open crown

In practice, the history of that most racially mixed country of all, the United States, supports this idea.

ECONOMIST: Darwinism