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