U.S. Economists Sargent, Sims Win 2011 Nobel Prize

Americans Thomas Sargent of New York University and Christopher A. Sims of Princeton University have won the Nobel prize in economics.

In awarding the $1.5 million prize, with the formal title the Nobel Memorial Prize in Economic Sciences, the Royal Swedish Academy of Sciences cited the researchers "for their empirical research on cause and effect in the macroeconomy."

Since the economics Nobel was first awarded in 1969, more than 40 Americans have received the award.

Last week, American Bruce Beutler and Frenchman Jules Hoffmann won the medicine prize for their research on innate immunity, when receptor proteins activate the first line of defense in the immune system after they recognize bacteria and other microorganisms as they enter the body.

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.

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, while Israeli scientist Dan Shechtman won the chemistry award for his discovery of quasicrystals, a mosaic-like chemical structure that researchers previously thought was impossible.

Acclaimed Swedish poet Tomas Transtromer won the literature prize and Liberian President Ellen Johnson Sirleaf, Liberian activist Leymah Gbowee and Tawakkul Karman of Yemen shared the Nobel Peace Prize "for their nonviolent struggle for the safety of women and for women's rights to full participation in peace-building work".

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