Advances in kidney exchange, in the New England Journal of Medicine

One of the satisfying things about the ongoing collaboration between economists and kidney surgeons is that sometimes the results are very concrete. Today's New England Journal of Medicine reports on such a case in the article: Rees, Michael A., Jonathan E. Kopke, Ronald P. Pelletier, Dorry L. Segev, Matthew E. Rutter, Alfredo J. Fabrega, Jeffrey Rogers, Oleh G. Pankewycz, Janet Hiller, Alvin E. Roth, Tuomas Sandholm, Utku Ünver, and Robert A. Montgomery, “A Non-Simultaneous Extended Altruistic Donor Chain,” New England Journal of Medicine, 360;11, March 12, 2009. The paper reports a chain of kidney surgeries that resulted in ten transplants. It began with an altruistic donor, and was able to accomplish so many transplants because they didn't all have to be done simultaneously. There's a simple economic idea at work here. Mostly in kidney exchange, all the surgeries are done simultaneously. The reason is that if two patient-donor pairs are exchanging kidneys, and if one pair were to donate a kidney to the other first, and the other were subsequently unable or unwilling to reciprocate, the pair that donated the kidney would be severely harmed; not only wouldn't they get the kidney they had been counting on, but they would have donated their donor's kidney and thus be unable to participate in a future exchange. But if there is an altruistic donor who doesn't have a specific patient in mind, and if he or she gives to a patient-donor pair, and they can't subsequently continue the chain, that is a loss, but no one is irreparably harmed. So, when chains begin with an undirected donor, they don't have to be simultaneous, since the costs of a breach are less. Mike Rees and the Alliance for Paired Donation are the heroes of this story: here is the APD's press release. Here's a story from the Boston Globe, that emphasizes the Boston/economist connection of Roth, Sonmez and Unver: Kidney-transplant chain broadens donations. Here's an article from the Pittsburgh Post Gazette that takes note of the collaboration with Carnegie Mellon computer scientists, represented in the NEJM paper by Tuomas Sandholm: Altruistic kidney donations.

Barter and illiquidity in Russia

The NY Times reports that in Russia, where rubles are getting scarce but prices are remaining sticky, there's a growing interest in barter exchanges:
Have Car, Need Briefs? In Russia, Barter Is Back .

"Advertisements are beginning to appear in newspapers and online, like one that offered “2,500,000 rubles’ worth of premium underwear for any automobile,” and another promising “lumber in Krasnoyarsk for food or medicine.” A crane manufacturer in Yekaterinburg is paying its debtors with excavators.
And one of Russia’s original commodities traders, German L. Sterligov, has rolled out a splashy “anti-crisis” initiative that he says will link long chains of enterprises in a worldwide barter system.
All this evokes a bit of déjà vu. In the mid-1990s, barter transactions in Russia accounted for an astonishing 50 percent of sales for midsize enterprises and 75 percent for large ones."
...
"Among the most upbeat of [the proponents of barter] is Mr. Sterligov, who, just as the credit crunch brought most business deals to a halt, shoveled $13 million into the Anti-Crisis Settlement and Commodity Center.
...He plans to use a computer database to create chains of six or seven enterprises having difficulty selling their products for cash, in which the last firm on the chain would pay the first in a single cash transaction.
It is the kind of multiparty barter that rose to prominence in the 1990s, when managers of factories across Russia devised complex barter chains to keep the maximum number of enterprises in business when none had cash to pay their bills. A computer, he said, can do the same job faster and more efficiently. "

Loyal followers of this blog will note the resemblance to some kinds of kidney exchange (most notably list exchange chains and altruistic donor chains).

Market for processed food

The task of tracking down a salmonella outbreak having to do with peanuts casts some light on just how many suppliers are involved in the production of some of the food we eat. List of Tainted Peanut Butter Items Points to Complexity of Food Production

Investigators have now focused on products from a particular manufacturer:
"The plant also produced peanut paste, a more concentrated product used in candy, crackers and many other kinds of foods. Tracking how the paste travels through the food supply can be challenging, because several companies can be involved in making the final food. For example, one manufacturer might coat the paste in chocolate and make a peanut butter cup, which is then sold to another company that mixes it into ice cream that may or may not also contain peanut butter. A grocery chain might buy that ice cream and sell it under a private label."

In the meantime, the Girl Scouts have issued a statement that their peanut butter cookies are safe.