This week, once you're through the 'sketch', Gareth discusses a novel approach to countering light pollution by making LEDs flicker 150 times per second, and Bill looks forward to this year's Lumiere festival in Durham, England which will feature Rafael Lozano-Hemmer's Pulse Topology and brings back memories of the Venice Biennale in 2007 (the photo is Gareth and Colin interviewing Rafael)