The atomic arrangements in condensed matter play an ever increasing role in many areas of science and technology - Materials Science and Engineering, Chemistry, Physics, Geology, Biology and Electrical, Civil, Mechanidtl and Chemical Engineering. Exciting discoveries in these fields in this century often stemmed from studies of these arrangements using diffraction: the structure and functions of DNA and other biological molecules, the configuration of polymer chains, the crystalline nature of metals and their imperfections, semiconductors and insulators, and -the links between their...