new york is a center of scientific research, particularly in medicine and the life sciences. the city has 15 nationally leading academic medical research institutions and medical centers. these include rockefeller university, beth israel medical center, columbia-presbyterian medical center, weill cornell medical college, mount sinai medical center (where jonas salk, developer of the vaccine for polio as an intern) and mount sinai school of medicine, memorial sloan-kettering cancer center, and the medical schools of new york university. in the bronx, the albert einstein college of medicine is a major academic center. brooklyn also hosts one of the country's leading urban medical centers, suny downstate medical center, an academic medical research institution and the oldest hospital-based medical school in the united states. professor raymond vahan damadian, a pioneer in magnetic resonance imaging research, was part of the faculty from 1967 to 1977 and built the first mri machine, the indomitable, there. the new york structural biology center, in upper manhattan, is a highly regarded federally funded medical research center with the largest and most advanced cluster of high-field research magnets in the united states. more than 50 bioscience companies and two biotech incubators are located in the city, with as many as 30 companies spun out of local research institutions each year.