(Portland, OR)  --  A man is dead, following a head-on crash involving a TriMet bus in Portland.  Police say the wreck happened around 6:20 last night in the area of Southeast 104th Avenue and Mt. Scott Boulevard.  Authorities say a man traveling downhill veered over the center line and slammed into the oncoming bus.  He died later at a hospital.  The bus driver suffered injuries that were not life-threatening.