Leo R. Kouwenhoven, Charles M. Marcus, Paul L. McEuen, Seigo Tarucha, Robert Westervelt, and Ned S. Wingreen. To be published in the proceedings of the Advanced Study Institute on Mesoscopic Electron Transport, edited by L.L. Sohn, L.P. Kouwenhoven, G. Schon
(Kluwer 1997)