Science: In her Issues and Perspectives column, Beryl Lieff Benderly examines the views on immigration of Norman Matloff, a computer science professor at the University of California, Davis. Matloff is particularly concerned about the H-1B visa, which is used by universities to hire postdocs and by tech companies to hire workers. Matloff is skeptical that the shortages purportedly being filled by H-1B holders really exist.