Democratic presidential nominee Sen. Barack Obama will appear at Carnegie Mellon University Thursday, hosting a round-table conversation on competitiveness and the world economy. The morning panel discussion, which will be closed to the public, includes speakers from industry, labor and the academic world.The participants are to include: Lael Brainard, vice president of the Brookings Institution; Eli Broad, founder of the Broad Foundation; Geoffrey Canada, president and CEO of Harlem Children's Zone; Steve Case, chairman and CEO of Revolution Health and former chairman and CEO of America Online; Susan Hockfield, president of the Massachusetts Institute of Technology; Federico Pe??a, former U.S....