The Minnesota Nurses Association have told hospital negotiators that it intends to file a strike notice on Friday, setting the stage for a walkout against Twin Cities hospitals that could begin as soon as July 5. The notification came after negotiators for the two sides sat down with a federal mediator for the first contract talks in almost three weeks. The nurses voted overwhelmingly to authorize a strike, but union officials said they would postpone calling a strike as long as there were "productive" negotiations.