A Representative from Illinois; born in Madison, Wis., October 7, 1955; B.A. University of Wisconsin, Madison, Dane County, Wis., 1975; Ph.D., Harvard University, Cambridge, Mass., 1984; physicist; senior physicist, Fermi National Accelerator Laboratory; entrepreneur; fellow, American Physical Society; elected as a Democrat to the One Hundred Tenth Congress, by special election, to fill the vacancy caused by the resignation of United States Representative John Dennis Hastert, and reelected to the succeeding Congress (March 8, 2008-January 3, 2011); unsuccessful candidate for reelection to the One Hundred Twelfth Congress in 2010; elected as a Democrat to the One Hundred Thirteenth and to the five succeeding Congresses (January 3, 2013-present).