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 Jewish. During the French Academy of Sciences elections, she was vilified by the right-wing press as a foreigner and atheist. Her daughter later remarked on the French press' hypocrisy in portraying Curie as an unworthy foreigner when she was nominated for a French honor, but portraying her as a French heroine when she received foreign honors such as her Nobel Prizes. In 1911 it was revealed that in 1910-11 Curie had conducted an affair of about a year's duration with physicist Paul Langevin, a former student of Pierre Curie's, a married man who was estranged from his wife. This resulted