Among {HEAD ~ the factors} considered in the optimization are {TAIL ~ the characteristics} of the originating source and the network path 
are
Among { HEAD ~ the factors } considered in the optimization are { TAIL ~ the characteristics } of the originating source and the network path
OTH HEAD HEAD HEAD HEAD HEAD HEAD OTH OTH OTH OTH REL TAIL TAIL TAIL TAIL TAIL TAIL OTH OTH OTH OTH OTH OTH OTH OTH