Much of the revival in deal activity reflects a build-up in the capital that firms hold.

ECONOMIST: Are private-equity firms able to escape their past?

The idea that more brain cell activity could lead to more amyloid-beta build up is an exciting, if sobering, finding.

FORBES: Wandering into Alzheimer's: Could Your Thoughts Reduce Your Risk?

It is thought that a build up of chemicals like dopamine suppresses the activity of the brain's natural painkillers - the endogenous opioids.

BBC: Gene controls pain threshold

It is not clear, for example, how such a large position was allowed to build up over the three-month period that the activity was said to be taking place.

ECONOMIST: UBS��s trading loss

The Americans have hoped in vain that, once the insurgent grip is weakened in any town, the Iraqi police would over time build up the networks of informants they need to nip rebel activity in the bud.

ECONOMIST: Iraq