(Roseburg, OR)  --  There's still no word on why a Rock Creek woman disappeared after attending a self-improvement conference in Portland.  Authorities say Demi Helenius left for personal reasons and that she was "not in danger and in very good health."  The Washington County Sheriff's Office says a public tip led them to the 23-year-old in Roseburg on Tuesday night.  Helenius had disappeared Saturday night after attending the Landmark Worldwide Forum near the Portland Airport.  Police found the woman's car about ten miles south of Creswell on the I-5 corridor in the town of Cottage Grove on Monday and her cell phone turned up at a Creswell Dairy Queen the night she disappeared.