The April issue of LUX is online. The article “The stroboscopic effect of LED lighting”, on page 6, focuses on the stroboscopic effect caused by the light scintillation of LED lamps which, under certain circumstances, may cause accidents in rotating machines. See on page 10 the article “App for customized lighting”, about an interactive project enabling personalized lighting control of a square by means of cell phones; it is an open system for LED luminaires. This issue also introduces the “Emergency lighting products and systems" buyers’ guide.