A method for refining a DC-Offset estimate and removing of the DC-Offset includes the step of determining if any AM is present. A measurement circuit receives the light signals and provides outputs separated in time which are indicative of the phase of the respective light signals. Each passageway has associated therewith a discharge guide vane, each discharge guide vane being disposed within a respective passageway and located closer to one or the other of the pumping vanes and projecting from the inner main face of at least one of the or each shrouds. Through computer-human interfaces, the user can move forwards andor backwards while replaying the collected historical workflow information. An axial thickness of the dustproof cushion is used to compensate a clearance formed between the sleeve bearing and the shaft seat, and a diameter of the dustproof cushion is smaller than an outer diameter of the shaft seat to prevent from precipitation of dust on the sleeve bearing. The invention also concerns related aspects including processes for the preparation of such compounds, pharmaceutical compositions containing one or more of those compounds and especially their use as orexin receptor antagonists.