Some musicians not normally associated with cyberpunk have at times been inspired to create concept albums exploring such themes. Albums such as Gary Numan's "Replicas", "The Pleasure Principle" and "Telekon" were heavily inspired by the works of Philip K. Dick. Kraftwerk's "The Man-Machine" and "Computer World" albums both explored the theme of humanity becoming dependent on technology. Nine Inch Nails' concept album "Year Zero" also fits into this category. Fear Factory concept albums are heavily based upon future dystopia, cybernetics, clash between man and machines, virtual worlds. Billy Idol's "Cyberpunk" drew heavily from cyberpunk literature and the cyberdelic counter culture in its creation. "1. Outside", a cyberpunk narrative fueled concept album by David Bowie, was warmly met by critics upon its release in 1995. Many musicians have also taken inspiration from specific cyberpunk works or authors, including Sonic Youth, whose albums "Sister" and "Daydream Nation" take influence from the works of Philip K. Dick and William Gibson respectively. Madonna's 2001 Drowned World Tour opened with a cyberpunk section, where costumes, asethetics and stage props were used to accentuate the dystopian nature of the theatrical concert.