Radar is among the thousand magazines, many of them defunct, that are to be booted from the shelves of Wal-Mart, the superstore chain which dominates retail in middle America. But the Manhattan title's Maer Roshan, who has launched and relaunched his gossipy magazine three times, never gives up. To better understand the needs of readers to the west of the Hudson, we're told, Radar staffers are being sent out to Chicago, to listen in on focus groups.