 Another early mentor at the Courant Institute was Fritz John, a mathematician of the highest character with whom Sirovich later started the eminent Applied Mathematical Sciences series, of Springer-Verlag Publishing.Sirovich's early research was in kinetic theory, its connection with fluid mechanics, and such areas of fluid mechanics as supersonic flow and turbulence.A turning point in Sirovich's research came with his reading of Jim Watson's "The Double Helix", which caused Sirovich to realize that he was not engaged in the heroic research of his time.