Four of the five 1998 Nobel Prize winners in Physics and Chemistry are no strangers to the ICTP. The three prize winners in physics, all currently working in the United States, were honored for their discovery of the "fractional quantum Hall" effect. The effect reveals that at very low temperatures and in the presence of a strong magnetic field, electrons clump together to form "quasi-particles" with electric charges less than those of individual electrons. US-born Robert N. Laughlin of Stanford University has visited the ICTP four times, including this year at the Third Trieste Conference on Statistical Field Theory. German-born Horst L. Stoermer, on the faculty of Columbia University in New York and staff of Lucent Technologies (formerly Bell Laboratories) in New Jersey, has spoken at three ICTP symposia, including the Centre's 25th Anniversary Conference on Frontiers in Physics, High Technology and Mathematics. He will return to the ICTP next July for the First Stig Lundqvist Research Conference on Advancing Frontiers in Condensed Matter Physics. And Chinese-born Daniel C. Tsui, who teaches at Princeton University, has tutored at the Symposium on Frontiers in Condensed Matter Physics in 1990. Meanwhile, Austrian-born Walter Kohn will share the 1998 Nobel Prize in Chemistry with UK-born John A. Pople of Northwestern University. The two scientists, both trained as physicists, have been honored for devising computations that enable their colleagues to model chemical reactions that are difficult to obtain in the laboratory. Kohn, who is a professor emeritus at the University of California at Santa Barbara, visited the ICTP frequently between 1985 and 1993.