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