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