  Knowing the state of our health at every moment in time is critical for
advances in health science. Using data obtained outside an episodic clinical
setting is the first step towards building a continuous health estimation
system. In this paper, we explore a system that allows users to combine events
and data streams from different sources to retrieve complex biological events,
such as cardiovascular volume overload. These complex events, which have been
explored in biomedical literature and which we call interface events, have a
direct causal impact on relevant biological systems. They are the interface
through which the lifestyle events influence our health. We retrieve the
interface events from existing events and data streams by encoding domain
knowledge using an event operator language.
