In the sport of orienteering, a competitor uses a detailed map (and perhaps a compass) to navigate his or her way across varied terrain following a course drawn on the map. Selecting the best available route, each participant races from one marker to the next in the required sequence. The winner is the person who completes the course in the shortest time.Even in recreational orienteering, participants typically start off at staggered times. In that way, each person (or group) navigates the course individually and obtains no help from others on the course. In practice, however, competitors some...

To accompany the telling of a story or recounting of a fable, men of the Chokwe people in south-central Africa traditionally made sand drawings, called sona, to illustrate the tale. These highly stylized geometric illustrations also served as memory aids.The storyteller would clean and smooth the ground, then use his fingertips to press into the sand a rectangular grid of equidistant dots. As he talked, he would trace a winding line among the dots. More often than not, he would draw the line in one continuous motion to create a closed loop. A line could intersect itself but could not be traced...

This week, the Food and Drug Administration is expected to announce its authorization of food-labeling claims for choline. It marks the first nutrient to be approved for such claims under the FDA Modernization Act of 1997.Although choline is hardly a household name, its low visibility doesn't reflect its importance. This micronutrient not only helps maintain the structural integrity of membranes surrounding every cell in the body but also can play a role in nerve signaling, cholesterol transport, and energy metabolism.Whereas the traditional U.S. diet probably contained plenty of choline, peop...

This week, the Food and Drug Administration is expected to announce its authorization of food-labeling claims for choline. It marks the first nutrient to be approved for such claims under the FDA Modernization Act of 1997.Although choline is hardly a household name, its low visibility doesn't reflect its importance. This micronutrient not only helps maintain the structural integrity of membranes surrounding every cell in the body but also can play a role in nerve signaling, cholesterol transport, and energy metabolism.Whereas the traditional U.S. diet probably contained plenty of choline, peop...

This week, the Food and Drug Administration is expected to announce its authorization of food-labeling claims for choline. It marks the first nutrient to be approved for such claims under the FDA Modernization Act of 1997.Although choline is hardly a household name, its low visibility doesn't reflect its importance. This micronutrient not only helps maintain the structural integrity of membranes surrounding every cell in the body but also can play a role in nerve signaling, cholesterol transport, and energy metabolism.Whereas the traditional U.S. diet probably contained plenty of choline, peop...

This week, the Food and Drug Administration is expected to announce its authorization of food-labeling claims for choline. It marks the first nutrient to be approved for such claims under the FDA Modernization Act of 1997.Although choline is hardly a household name, its low visibility doesn't reflect its importance. This micronutrient not only helps maintain the structural integrity of membranes surrounding every cell in the body but also can play a role in nerve signaling, cholesterol transport, and energy metabolism.Whereas the traditional U.S. diet probably contained plenty of choline, peop...

You're confined to a single lane as you drive along a narrow, winding road. The car in front of you suddenly slows, then just as inexplicably accelerates a short time later, only to slow again. As you keep adjusting to the leading car's erratic speed changes, you sometimes find a clump of vehicles closely tailing you and, at other times, only a few vehicles in sight.From a physicist's point of view, traffic flow can be regarded as a "many-body system of strongly interacting bodies." Various studies have revealed that such systems can show wavelike behavior and abrupt transitions from one state...

You're confined to a single lane as you drive along a narrow, winding road. The car in front of you suddenly slows, then just as inexplicably accelerates a short time later, only to slow again. As you keep adjusting to the leading car's erratic speed changes, you sometimes find a clump of vehicles closely tailing you and, at other times, only a few vehicles in sight.From a physicist's point of view, traffic flow can be regarded as a "many-body system of strongly interacting bodies." Various studies have revealed that such systems can show wavelike behavior and abrupt transitions from one state...