Complex sentence: Sidman took his PhD at Columbia in 1952 under the advisorship of William N. Schoenfeld, has worked at many research institutions including Harvard Medical School, Johns Hopkins University Medical School, and the Walter Reed Army Institute of Research.
Split into simpler sentences: Sidman took his PhD at Columbia in 1952 under the advisorship of William N. Schoenfeld. He has worked at many research institutions, including Harvard Medical School, Johns Hopkins University Medical School, and the Walter Reed Army Institute of Research.