The intensity of {HEAD ~ the reflective ultrasonic signals} is used to determine the location of {TAIL ~ a preselected body structure} 
The intensity of { HEAD ~ the reflective ultrasonic signals } is used to determine the location of { TAIL ~ a preselected body structure }
OTH OTH OTH HEAD HEAD HEAD HEAD HEAD HEAD HEAD HEAD OTH OTH OTH OTH OTH OTH OTH TAIL TAIL TAIL TAIL TAIL TAIL TAIL TAIL