The prestigious Nobel Prizes are awarded annually on Dec. 10 in twin ceremonies in Stockholm and Oslo.
Here is a look at this year's winners and their work:
_ Nobel Prize in physiology or medicine: Bruce Beutler of the U.S. and Frenchman Jules Hoffmann won the Nobel Prize in medicine for their discoveries concerning the activation of innate immunity. They shared it with Canadian-born Ralph Steinman, who died three days before the announcement, and who was honored for his discovery of the dendritic cell and its role in adaptive immunity.
_ Nobel Prize in physics: U.S.-born scientists Saul Perlmutter, Brian Schmidt and Adam Riess won the physics prize for discovering that the universe is expanding at an accelerating pace.
_ Nobel Prize in chemistry: Israeli scientist Dan Shechtman won the Nobel Prize in chemistry for his discovery of quasicrystals, a mosaic-like chemical structure that researchers previously thought was impossible.
_ Nobel Prize in literature: Swedish poet Tomas Transtromer, whose surrealistic works about the mysteries of the human mind won him acclaim as one of the most important Scandinavian writers since World War II, was awarded the Nobel Prize in Literature for giving the world fresh access to reality "through his condensed, translucent images."
_ Nobel Peace Prize: Liberian President Ellen Johnson Sirleaf, Liberian activist Leymah Gbowee and Tawakkul Karman of Yemen were honored "for their nonviolent struggle for the safety of women and for women's rights to full participation in peace-building work".
_ The Nobel Memorial Prize in Economic Sciences: To be announced on Monday, Oct. 10.