MADISON, Wisconsin, Jan. 24 -- The University of Wisconsin Madison campus issued the following news: * * * An icy start to spring semester University of Wisconsin-Madison students returning to class on Tuesday were greeted by an arctic air mass that brought subzero temperatures and 20-below windchills. Some students made the most of winter by sledding; others refused to acknowledge it by wearing shorts. Luckily, by Friday temperatures reached a more seasonal 24 degrees. And students carried w  more