At a Glance With wind chills below zero, schools closed or delayed classes.An Iowa state trooper was hurt at the scene of a jackknifed semitrailer truck.Seventeen students were injured Wednesday when a bus slid off a highway near Emporia, Kansas. Schools and businesses remained closed or opened late Thursday as much of the Midwest was gripped by arctic cold. The temperature dropped to 3 degrees at Kansas City International Airport and the just before 8 a.m. CST, the National Weather...