The weak pull of artificial gravity, The Space Review
"Gerstenmaier, while skeptical of the need for and ability to accommodate artificial gravity, didn't rule it out entirely. He noted that there's very little information on the effectiveness of partial gravity, including the minimum levels needed to offset the deleterious effects of microgravity. Some of that research is being done with a small rodent centrifuge on the station's Kibo module. "We'll take a look and see if there's some magic partial gravity that actually mitigates most of the concerns of the zero-gravity levels," he said. Until then, astronauts on the ISS and future exploration missions will have to learn to take the good with the bad when it comes to weightlessness--and hope they love to exercise for a couple hours every day."
Keith's note: Well, DUH, Bill. You guys cancelled the 2.5 meter centrifuge facility that was supposed to fly on ISS to answer those exact same questions. Gee, I wonder why they have not been addressed? Don't try and duck the issue: I can remember sitting in meetings where it was discussed that you attended back in the day ;-)