def self.vote_down_thr(current_object,user)
        a = current_object.activities.build(:user_id=>user.id,:name=>'vote_down')
        a.build_points(:value=> APP_REPUTATION['vote_down_thr'])
        a.build_points(:reduce_points_if_needed=>true,:user_id=>current_object.user.id,:value => APP_REPUTATION['thr_receives_down_vote'])
        self.on_vote_thr(current_object,user)