Narrator:     This is Science Today. More than half of all health care providers in this country are nurses and in hospitals, nurses constitute the bulk of care. Mary Blegen, a professor at the University of California, San Francisco School of Nursing, says physicians prescribe and diagnose care and they perform surgeries, but it's the nurses who provide around-the-clock nursing care and this in turn impacts patient mortality.

Blegen:     There has been research that has shown that the more nurses are around, the lower the mortality rate or the fewer patients that will die because of that reason. Because they're there to watch, observe and notify other people as soon as things begin to look as though they're going downhill.

Narrator:     Blegen, who heads the school's Center for Patient Safety, is leading one of nine nationwide projects looking into measuring nursing quality in hospitals.

Blegen:     We're really combining the expertise and the interest in research with education and student training and then with actual projects that go on in hospitals or other healthcare settings to improve safety, so it has a pretty broad mission that will cover all of those.

Narrator:     For Science Today, I'm Larissa Branin.