Today's Globe: senior training, stem cell source, teen dinosaur mothers, nutrition leader at 90, dietary guideline critics, hospital help, health law holes

A new emphasis on aging is part of a wave of change sweeping medical schools nationwide as they focus - many for the first time - on preparing all newly minted doctors to treat the growing population of older Americans. (Left, medical student Matthew Deren brings Lillian Donohue her wheelchair at the Winslow Gardens assisted living facility.)

Scientists at Children's Hospital Boston have forged stem cells from the "flawed" and "poor quality" early-stage embryos that in vitro fertilization clinics discard by the hundreds of thousands every year, according to research published yesterday in the journal Nature Biotechnology.

New research, published in the Proceedings of the National Academy of Sciences, adds support for the idea that dinosaurs had babies starting in adolescence.

Dr. Nevin Scrimshaw (at right, celebrating his 90th birthday with his granddaughters), one of the fathers of the nutrition movement, is more than just a nonagenarian capable of barreling down a mountain on a pair of planks. He is still an institute professor emeritus at MIT as well as an adjunct professor at Tufts University, a senior adviser to United Nations University, and president of the Boston-based International Nutrition Foundation, a food and nutrition advocacy group for developing countries.

Last week, a group of respected epidemiologists called for a rethinking of the Dietary Guidelines for Americans, the nutrition advice to the public and the standard for all federally subsidized meals from school lunches to military rations.

Also in Health|Science, how zealous do you really need to be about removing ear wax and why does my lamp's touch switch work when I use my hand, but not when I use a newspaper?

In Business & Innovation, to cut costs while improving the experience for patients, healthcare institutions are adopting cutting-edge business tactics to improve their processes.

Commonwealth Connector head Jon Kingsdale is a good man playing a bad hand dealt him by the Massachusetts Legislature and the Bush administration, Robert Kuttner writes on the op-ed page.