But Dr Arendt's group has made the startling discovery that hibernating brains accumulate a protein called hyperphosphorylated tau.

ECONOMIST: Dementia

Dr Arendt's group is now engaged in discovering exactly how the tau protein can be cleared from the brain.

ECONOMIST: Dementia

If you cannot quite imagine Berlin posting to Twitter, then think how well he would put, say, Hannah Arendt in her place, on bloggingheads.tv.

ECONOMIST: And what it says about the role of public intellectuals

This has led Dr Arendt to suggest that rather than being a part of a disease process, the formation of the tau protein could be a mechanism by which the brain protects itself.

ECONOMIST: Dementia

Chris Arendt, a former guard at Guantanamo Bay, says the Obama administration must rethink and reform the way it detains and prosecutes future terror suspects -- and do more than just close Guantanamo.

CNN: Open or closed, Guantanamo hurts U.S., ex-inmate says

Just two streets away is the restored and ritzy Kempinski Hotel, where German celebrities drink burnt orange brandy and philosophize, just as journalist Hannah Arendt and her lover did before the Second World War.

BBC: A tale of two Berlins