A microscope that can see objects smaller than an atom. The first field test of a fleet of electric vehicles powered by fuel cells. A tariff to limit vehicular traffic in central London. These are but a few of the path-breaking developments that have taken place in recent months in laboratories, corporate suites and the halls of government. For the second year, the SCIENTIFIC AMERICAN 50 recognizes the singular accomplishments of those who have contributed to the advancement of technology in the realms of science, engineering, commerce and public policy. This year¿s selections by the Board of Editors pay tribute to individuals, teams and companies that have stood out in a wide variety of technological disciplines. It also honors Leaders of the Year for achievements in research, business and policy. Their work again demonstrates the ingenuity and resourcefulness that generate the ever more sophisticated tools and solutions for meeting society¿s needs. --The Editors

Biographies of the three Leaders of the Year follow below. For a complete list of winners, click here. For a full description of their work, visit Scientific American Digital and purchase the December issue.

RESEARCH LEADER OF THE YEAR

Roderick MacKinnon
Professor of molecular neurobiology and biophysics, Rockefeller University; investigator, Howard Hughes Medical Institute
Elucidated the structure and function of ion channels, particularly the potassium ion channel.

That electricity might animate mere flesh goes all the way back to Frankenstein, yet the mechanisms remained vague until Roderick MacKinnon, a physician, worked out the structure of the potassium channel. Then, this past spring, he deduced the mechanism by which a potassium channel senses electricity--its voltmeter, as it were. These achievements won him the 2003 Nobel chemistry prize.

When a channel for any one of three inorganic ions--calcium, sodium or potassium--senses a voltage, it opens to allow ions in or out, changing the concentration and thus effecting a behavior, such as neural discharge, muscular contraction or hormone secretion. We could neither think nor move nor survive for many minutes without these channels, and MacKinnon's explanation of them should guide the development of drugs for neuromuscular and other disorders, such as cystic fibrosis and cardiac arrhythmias. Drug companies should show particular interest in the implications for arrhythmia, a common pharmaceutical side effect in numerous patients that has cost them billions in failed clinical trials.

The challenge here, as in the earlier research, lay in forming a crystal of the pore proteins that was good enough to diffract x-rays into patterns a computer could render into images. The task is hard because the proteins are very large and mixed in oils that must be removed with detergent, which is itself a problem. Furthermore, the volt-sensing element has moving parts that are buried deep inside the protein. Interestingly, MacKinnon studied the voltmeter in an Archaebacterium taken from a superhot ocean vent. That an organism so far removed in evolutionary history from us should have such similar channels indicates that the structures were highly resistant to mutation over eons and thus critical to survival.

BUSINESS LEADER OF THE YEAR
Toyota Motor Corporation
Toyota City, Japan
Commercialized affordable hybrid cars.

Whereas most other automakers have merely talked of combining internal-combustion engines with electric motors, Toyota has actually been selling such a hybrid car for years. Called the Prius, it came out first in Japan in the late 1990s and soon after in the U.S. Toyota's 2004 Prius, due out in October, appears to get around the dismal engineering trade-offs associated with hybrids by improving performance and fuel economy over last year's model while keeping the price the same, around $20,000.