What's stopping us from building useful quantum computers? And how long until we'll have them?

The travels of bank notes give important clues to epidemiologists
Is geometry hard-wired into our brain?
The next total eclipse of the Sun will be in March 2006
How to interact with your music collection
Learning about the history behind maths helps students understand it better
The GIMPS project finds a new Mersenne prime
UK students visit South Africa