Karl Landsteiner ("tuberculinum prestinum"). He also published a number of papers, five of them being published in Dutch by the Royal Academy of Sciences. Yet working conditions proved to be not much better than in post-war Vienna. So Landsteiner accepted the invitation that reached him from New York, initiated by Simon Flexner, who was familiar with Landsteiner's work, to work for the Rockefeller Institute. He arrived there with his family in the spring of 1923. Throughout the 1920s Landsteiner worked on the problems of immunity and allergy. In 1927 he discovered new blood groups: M, N and P, refining the work he
Nobel Prize controversies Chao was the first to experimentally identify positrons through electron–positron annihilation, but did not realize what they were. Anderson, Chao's classmate at Caltech, used the same radioactive source, , as Chao. (Historically, was known as "thorium C double prime" or "ThC", see decay chains.) Fifty years later, Anderson admitted that Chao had inspired his discovery: Chao's research formed the foundation from which much of Anderson's own work developed. Chao died in 1998, without sharing in a Nobel Prize acknowledgment. The 1923 prize went to Robert Millikan "for his work on the elementary charge of electricity and on the photoelectric effect".