The transformer that provides electricity to the AMS building in Providence went down on Sunday, April 22. The restoration of our email, website, AMS Bookstore and other systems is almost complete. We are currently running on a generator but overnight a new transformer should be hooked up and (fingers crossed) we should be fine by 8:00 (EDT) Wednesday morning. This issue has affected selected phones, which should be repaired by the end of today. No email was lost, although the accumulated messages are only just now being delivered so you should expect some delay.
Thanks for your patience.
"Lofty Lingo Boils Down to Dissection of Traffic," by Carl T. Hall. SanFrancisco Chronicle, 8 January 2001.
"The Physics of Gridlock," by Stephen Budiansky. The Atlantic Monthly,December 2000, pages 20-24.
These two articles discuss the perplexing problem of constructing mathematicalmodels of traffic flow. The article by Hall describes research by H. MichaelZhang, a civil engineer at the University of California, Davis. Most modelsview traffic as a kind of plumbing system in which the cars move as if in aflowing liquid. Other models stress the individual behavior of drivers.Zhang's work is significant because it "represents an attempt to tie severalelements together in a single computer model," the article says.
The article by Budiansky reports on recent work by a group of theoretical physicistsin Germany. Their models, based on well-established equations describing themovement of gas molecules, resulted in some unexpected conclusions, such as thenotion that traffic congestion can arise spontaneously with no apparent cause.The research has caused some controversy among traffic engineers.
--- Allyn Jackson