| 2010 | Clinical Advisor, Laboratory of Biomedical Engineering, Cornell College of Engineering, Cornell University, USA |
| 2002 - Present | Professor of Medicine, Cornell University Medical College, USA |
| 2002 - Present | Director, Leukemia and Myeloproliferative Center, New York Presbyterian Hospital, USA |
| 1973 - Present | Attending Physician, New York Presbyterian Hospital, USA |
| 1973 - 2002 | Clinical Professor of Medicine, Cornell University Medical College, USA |
| 1967 - 1973 | Associate Attending Physician, New York Presbyterian Hospital, USA |
| 1964 - 1967 | Assistant Attending Physician, New York Presbyterian Hospital, USA |
| 1963 - 1966 | Assistant Visiting Physician 2nd (Cornell) Med. Div., Bellevue Hospital, USA |
| 1958 - 1964 | Physician to Outpatients, New York Presbyterian Hospital, USA |
| 1957 - 1958 | Resident, Medicine (Hematology), The New York Hospital Cornell Medical Center, USA |