To diagnose anemia, a condition that can signal the presence of diseases such as HIV, doctors need a centrifuge to separate blood samples into red blood cells and plasma. Lila Kerr and Lauren Theis modified a salad spinner to do the job in areas without electricity. The Rice University undergraduates created the device as part of their coursework in introductory bioengineering and field-tested it this summer in Ecuador, Swaziland, and Malawi. "The most frequent response" to the gadget, says Kerr, "is 'well, of course!' After all, a salad spinner is a centrifuge."