The method 13 wherein determining {TAIL ~ a respective second intensity variation step} comprises {HEAD ~ the substeps} of: 
The method 13 wherein determining { TAIL ~ a respective second intensity variation step } comprises { HEAD ~ the substeps } of :
OTH OTH OTH OTH OTH TAIL TAIL TAIL TAIL TAIL TAIL TAIL TAIL TAIL TAIL OTH HEAD HEAD HEAD HEAD HEAD HEAD OTH OTH