Nobel Prizes 2012

Oops, almost forgot to do this feature. Every year I try to highlight the results of the Nobel Prizes that actually matter and aren’t completely spurious. I mean I guarantee that everyone in the Chinese-speaking world knows who won the literature prize and plenty of people who read the news are aware that the Peace Prize committee are keeping up their reputation for bizarre choices by picking the European Union. But how many people know who won the prizes for medicine, physics, chemistry and economics or what the discoveries were for? So that’s what this blog post is all about.

First up, the physics prize was won by Serge Haroche of the Collège de France, in Paris, and David Wineland of America’s National Institute of Standards and Technology. The two independently invented methods of directly observing quantum systems without destroying their superposition of states. Interestingly, they used opposite strategies. Dr. Wineland trapped ions and used photons to control and measure them. Dr. Haroche trapped photons and sent atoms through the trap to measure them. Both are real-life examples of the famous Schrödinger’s cat thought experiment, though on a far smaller macroscopic scale.

This development is thought to pave the way for quantum computers in the future, with quantum bits, or qubits, taking the place of traditional bits. Since each qubit can hold both 0 and 1 simultaneously and each additional qubit doubles the amount of available space, n qubits can hold 2n states simultaneously. So a system of only 300 qubits could hold more values than there are atoms in the universe. In old-fashioned bits, 300 bits is less than 40 bytes of information. In the meantime, Dr. Wineland has used his techniques to create the world’s most accurate clock. If it had been started at the beginning of the universe, 13.7 billion years ago, it would now be off only by about five seconds.

The chemistry prize went to Robert Lefkowitz of Duke University and Brian Kobilka of Stanford University for the study of what is now known as G-protein-coupled receptors (GCPRs). Receptors are sensors on the surface of cells that pass signals from the outside world into the interior of the cell. GCPRs in particular include receptors for adrenalin, dopamine, serotonin, light, flavor and odor. Around half of all the medications we use today act through GCPRs.

Dr. Lefkowitz’s role was in identifying several receptors using radioactive ligands, attaching radioactive iodine to a hormone, then when the hormone attaches to a cell, using the radioactivity to track the receptor. Later, he cloned the gene for beta adrenergic receptors. Dr. Kobilka was hired by Lefkowitz to join his team before moving on to Stanford. He set out to create an image of the receptor and successfully did so using x-ray crystallography. This led to further insight about the variations of receptors and their multifunctional nature. These discoveries are expected to yield new pharmaceutical drugs as scientists learn more about these receptors.

The prize for physiology or medicine went to Sir John Gurdon of Oxford University and Shinya Yamanaka of Kyoto University for their work in reprogramming mature, differentiated cells to a pluripotent stem cell state. Stem cells are those that can differentiate into all of the specialized cells that form the body. Researchers previously used stem cells from an embryonic source to study them but this was understandably a source of controversy. However, it was necessary because differentiated cells were long thought to be permanently locked and it was impossible to induce them to revert them into an undifferentiated state.

In 1962 Dr. Gordon transplanted the nuclei of cells from adult frogs into enucleated eggs of that species, which subsequently developed into healthy adults, proving that adult cells may in some cases be reverted back to its pluripotent stage after all. Dr. Yamanaka essentially did the same trick, except that he used adult mouse cells without involving eggs at all. He inserted extra copies of four key genes into the adult cells to trick them into behaving like embryos. He further proved that the process works just as well for human cells, generating pluripotent stem cells from adult cells. This opens the door for regenerative medicine, in which a patient’s own cells are used to grow new replacement organs. But as this excellent overview from The Economist points out, it also allows human cloning.

Finally the economics prize was won by Alvin Roth of Stanford University and Lloyd Shapley of the University of California, Los Angeles for what is essentially a match-making algorithm. The algorithm is known as the Gale-Shapley “deferred acceptance” algorithm, named after David Gale who died in 2008 and is therefore ineligible for the Nobel. The best way to explain it is to work through an example.

Assume that we have ten men and ten women who want to marry. Everyone ranks each of their prospective partners. Each of the men propose to the highest-ranked woman on their list. The women examine all of their proposals, retain the proposal that is from the highest-ranked man but does not accept it, and rejects the rest. The men who were rejected then propose to their next highest-ranked choices. The women again keep their best offer and reject the rest. The process continues until none of the men want to make further proposals (i.e. none were rejected). The women then accept the last proposal they retained.

While it’s hard to imagine this algorithm being used by anyone for actual romantic match-making, it turned out to be extremely useful for matching organ donors to recipients, matching newly graduated doctors to resident positions in hospitals and matching students to high schools. What is the most surprising thing about this algorithm, as both authors of the original 1962 paper pointed out, is that it is not actually very complicated. Yet no one had thought of it before them and no one else has mathematically proved it to result in the most stable outcomes, so it turns out to be a Nobel Prize-worthy effort.

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