 Complete the following phrase:  She was the Principal Investigator PI on a series of SpaceHabBiorack experiments, which examined the regulation of osteoblast bone cell growth. These experiments flew on STS-76, in March 1996, STS-81 in January 1997, and STS-84 in May 1997, and studied the root causes of osteoporosis that occurs in astronauts during spaceflight. One experiment resulted in observations of changes in anabolic signal transduction in microgravity. A later collaborator was Dr. Augusto Cogoli of Zürich, Switzerland; one experiment with Dr. Cogoli was lost in the 