U.N. Secretary-General Ban Ki-moon, right, and Edmond Mulet, the acting chief of the U.N. peacekeeping mission in Haiti, visit the collapsed U.N. headquarters in Port-au-Prince, Sunday, Jan. 17, 2010. (Xinhua/AFP Photo) PORT-AU-PRINCE, Jan. 17 (Xinhua) -- The United Nations Secretary General Ban Ki-moon arrived on Sunday in Port-au-Prince, the capital of Caribbean nation Haiti, which was...