This Week in Science This Week in Science + See all authors and affiliations Science 11 Jul 1986:Vol. 233, Issue 4760, pp. 139DOI: 10.1126/science.233.4760.139 Article Info & Metrics eLetters PDF This article has a correction. Please see:Erratum - August 22, 1986 This is a PDF-only article. The first page of the PDF of this article appears below.