(Portland, OR)  --  Portland police say a homeless man who was caught outdoors during freezing temperatures died Monday of hypothermia.  Authorities say Portland Fire & Rescue personnel who were sent to check on the man found him dead in front of a business on East Burnside Street.  The state medical examiner has identified the man as 51-year-old Mark Elliot Johnson.  Police say anyone who needs to find a nearby shelter is urged to call 211 for information.