Team USA's Stefanie Nation earned the topseed for the singles semifinals at the 2009 World Tenpin BowlingAssociation World Women's Championships in LasVegas on Tuesday, the United States Bowling Congress reported. Nation posted games of 228, 257, 205, 242, 206 and 223 for a1,361 total at Cashman Center to set the pace on the first of theday's three squads....