Marie Curie theory of "radioactivity" (a term that she coined), techniques for isolating radioactive isotopes, and the discovery of two elements, polonium and radium. Under her direction, the world's first studies into the treatment of neoplasms were conducted using radioactive isotopes. She founded the Curie Institutes in Paris and in Warsaw, which remain major centres of medical research today. During World War I, she developed mobile radiography units to provide X-ray services to field hospitals. While a French citizen, Marie Skłodowska Curie, who used both surnames, never lost her sense of Polish identity. She taught her daughters the Polish language and took
Marie Curie Fellows Association the European Commission. During its first three years the Association received a generous support from the European Commission. At the same time the "Marie Curie Fellowships Unit" at the Directorate-General for Research of the European Commission supported the Association with advice and logistical help. In 1999, the MCFA was awarded UNESCO's Niels Bohr Medal at the occasion of the World Conference on Science (Budapest 26 June - 1 July 1999). All activities of the MCFA are co-ordinated on the international level. The running of the Association lies in the hands of the Administrative Board that is elected by the members