Second, tough times are forcing firms to strain every brain cell to become more efficient.

ECONOMIST: How much longer can America keep increasing productivity?

But the strain on a lithium-ion cell in a plug-in is much greater than on the batteries in today's hybrids.

FORBES: Jump Start

When she created a strain of mice with the presenilin genes missing in their brains, the mice developed dementia and brain cell death just like Alzheimer's sufferers, but the mice had no amyloid deposits.

FORBES: Executive Health