Activities, Context and Ubiquitous Computing
  Context and context-awareness provides computing environments with the ability to usefully adapt the services or information they provide. It is the ability to implicitly sense and automatically derive the user needs that separates context-aware applications from traditionally designed applications, and this makes them more attentive, responsive, and aware of their user's identity, and their user's environment. This paper argues that context-aware applications capable of supporting complex, cognitive activities can be built from a model of context called Activity-Centric Context. A conceptual model of Activity-Centric context is presented. The model is illustrated via a detailed example. 
Paul Prekop and Mark Burnett