The test tracks changes in the electrical pattern of a person's cells, and it accurately flagged all CFS patients in a small group of 40 people, researchers report. "When we stress the cells, we can easily differentiate them based on the signal they are showing," said lead author Rahim Esfandyarpour. "It's a huge difference." [Rahim] Esfandyarpour worked on the test with a team while at Stanford University in California. He's now an assistant professor of electrical engineering and computer science at the University of California, Irvine.