Timothy G. Feeman is professor of mathematics, Villanova University, in Lancaster, Pennsylvania. His original area of research is the theory of operators on Hilbert spaces once described as "the field of mathematics that has the strongest interaction with the scientific and technological developments which are characteristic of the twentieth century." Since the mid- to late-1990s, his scholarly efforts have become more diversified. Professor Feeman is the author of The Mathematics of Medical Imaging, also published in the "Springer Undergraduate Texts in Mathematics and Technology" series.