{HEAD ~ Tp} is typically between 20 and 300 seconds and {TAIL ~ αt} between 0 and 5 
is typically
{ HEAD ~ Tp } is typically between 20 and 300 seconds and { TAIL ~ αt } between 0 and 5
HEAD HEAD HEAD HEAD HEAD REL REL OTH OTH OTH OTH OTH OTH TAIL TAIL TAIL TAIL TAIL OTH OTH OTH OTH