{HEAD ~ The heating elements} are pulsed by {TAIL ~ an electrical circuit} at a rate substantially faster than the rate of introduction of new assay cartridges 
are pulsed by
{ HEAD ~ The heating elements } are pulsed by { TAIL ~ an electrical circuit } at a rate substantially faster than the rate of introduction of new assay cartridges
HEAD HEAD HEAD HEAD HEAD HEAD HEAD REL REL REL TAIL TAIL TAIL TAIL TAIL TAIL TAIL OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH