This article is published under a Creative Commons Attribution License by Elsevier and available electronically from http://www.sciencedirect.com/science/article/pii/S0370269302025935.
Except where otherwise noted, this item's license is described as: This article is published under a Creative Commons Attribution License by Elsevier and available electronically from http://www.sciencedirect.com/science/article/pii/S0370269302025935.