Nobel Prize relevant fields was greater), a greater delay in awarding Nobel Prizes for women's achievements making longevity a more important factor for women (Nobel Prizes are not awarded posthumously), and a tendency to omit women from jointly awarded Nobel Prizes. Four people have received two Nobel Prizes. Marie Curie received the Physics Prize in 1903 for her work on radioactivity and the Chemistry Prize in 1911 for the isolation of pure radium, making her the only person to be awarded a Nobel Prize in two different sciences. Linus Pauling was awarded the 1954 Chemistry Prize for his research into the chemical
Cuban Five appeal courts." The U.S. Government has responded to these claims, stating that the prisoners have received over a hundred visits from family members granted visas. The government contends that the wives of González and Hernández are members of the Cuban Intelligence Directorate, and thus pose a risk to the national security of the United States: Eight international Nobel Prize winners wrote and sent a document to the U.S. Attorney General calling for freedom for the Cuban Five, signed by Zhores Alferov (Nobel Prize for Physics, 2000), Desmond Tutu (Nobel Peace Prize, 1984), Nadine Gordimer (Nobel Prize in Literature, 1991), Rigoberta