The PhotoMirror appliance: affective awareness in the hallway. - Panos Markopoulos 001; Bert Bongers; Erik Alphen; Jasper Dekker; Wouter Dijk; Sebastiaan Messemaker; Joep Poppel; Bram Vlist; Dirk Volman; Gilles van Wanrooij (Pers. Ubiquitous Comput., 2006)