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