The invention provides systems and methods to facilitate user thinking about an arbitrary problem and particularly about a complex or multiple part arbitrary problem or related problems. For example, the method acquires presence information associated with a user, packages the presence information into a message and forwards the message containing the presence information via a non-session initiated protocol based transport protocol to a presences access layer server. The controller allows for fast response to disturbances andor fast response of the medium temperature when the operating conditions of the refrigeration system are changed andor fast response during start-up of the refrigeration system and maintains stable operation conditions with low, but positive superheating and a stable evaporation pressure.