- WELCOME TO THE ADRIAN PIPER RESEARCH ARCHIVE APRA is a resource facility and web site (adrianpiper.com) established for the benefit of those students, scholars, curators, collectors, writers, and members of the general public who have a constructive curiosity or scholarly or professional interest in Adrian Piper's work in art, philosophy and yoga. APRA aims to promote a fuller and clearer ...www.adrianpiper.com