Let there be LED. A new technology developed by E. Fred Schubert could soon bring consumers a lightbulb that lasts a hundred years.

Invented in 1880, Edison's filament lightbulb is still used in most homes. More recently, fluorescent tubes and compact lightbulbs have made inroads in the lighting market. None of them, Schubert says, are particularly energy- or light-efficient.

Schubert, an ENG professor of electrical and computer engineering, has found a way to use photon recycling semiconductor light-emitting diodes (PRS-LEDs) -- which until now have been used only in signs and electronic devices -- to create a light with nearly 100 percent efficiency. Conventional lightbulbs are only 5 to 10 percent efficient and fluorescents only up to 30 percent.

LEDs are made of semiconductors, the material that transmits and controls electric currents and is used in personal computers. They are enormous energy- and money-savers because they work so efficiently. "Thirty percent of all electrical power generated is used for lighting," Schubert says. "Since so much electrical power is generated by oil-consuming power plants, our dependence on foreign oil could be substantially reduced if we replace power-hungry incandescent lights with LEDs." He says that within five years he'll have a prototype that is about 50 percent efficient -- already miles ahead of its competitors.

Schubert will soon apply for a patent on his technology. He says that a major lighting company has already shown interest in licensing it.

The best part of PRS-LED lighting is its versatility. "LEDs will offer new features, such as the ability to adjust the color of light in a room," he says. "It's possible that traditional lighting fixtures themselves will be things of the past. LEDs are so small that they could be distributed, unseen, throughout a home or office."

Schubert was invited to submit his innovation to Discover magazine for its Award for Technological Innovation.

High pressure today; high risk tomorrow. A new study by MED researchers has found that if people develop high blood pressure in middle age, they have a similar risk for a stroke as people whose hypertension occurs when they are much older -- even if the problem among the middle-aged is properly treated later in life.

High blood pressure is the single most common cause of stroke. Experts estimate that more than 700,000 Americans have a stroke each year, and the number is steadily increasing. Strokes interrupt blood flow to the brain, killing the cells by depriving them of oxygen.

Dr. Sudha Seshadri, a postdoctoral fellow in MED's neurology department, and her colleagues examined both the current blood pressure readings and records from prior decades of participants in the landmark Framingham Heart Study. They found that a 20-point rise in systolic blood pressure when people are in their 60s raises their stroke risk by 50 percent after they reach age 70. A 20-point elevation when people are in their 50s raises the risk 40 percent later on.

Blood pressure is read as systolic over diastolic. Systolic pressure occurs during contraction of the ventricles; diastolic occurs when the ventricles relax. A normal systolic reading is around 120.

According to Dr. Ralph Sacco of Columbia-Presbyterian Medical Center in New York, the study is important because it illustrates the impact of this risk factor over a lifetime. "The longer you have it," he says, "the greater its effect."

Seshadri presented the findings February 10 at a meeting of the American Stroke Association.

"Research Briefs" is written by Janice Zazinski in the Office of Public Relations. To read more about BU research, visit http://www.bu.edu/research.