Science  24 Jan 2003:
Vol. 299, Issue 5606, pp. 485

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  1. EDUCATION: Muscle Workout

    Students can bulk up their knowledge of muscle structure and function with this tutorial from the Muscle Physiology Lab at the University of California, San Diego. Whether we're grasping a pin or hefting a sack of potatoes, muscle contraction involves the same molecular events. The 23 chapters start by explaining the interaction between the overlapping proteins myosin and actin, which slide across one another to produce contraction. From there, students can explore topics such as muscle metabolism, how nerve signals spark contraction, and the physics of joint movement. The site also links to animations that show how the liaison between muscle proteins leads to movement.

  2. EXHIBIT: Exploring Canada's Frozen Outback

    On 1 January 1894, J. B. Tyrrell and his brother rode a dogsled into the frontier town of West Selkirk in Manitoba, Canada. The two had traveled more than 5000 kilometers by canoe, sled, and on foot as part of the first survey party to cross the “Barren Lands,” the huge unexplored area west of Hudson's Bay. Despite hardships that included dysentery, near starvation, and vicious cold, J. B. Tyrrell returned to the Barren Lands for a second season of exploring. At this site from the University of Toronto Libraries, you can follow the progress of this famous Canadian geologist's expeditions to the northland.

    Interactive maps and day-by-day chronologies link to some 5000 photos, letters, original maps, diary entries, press clippings, and other documents. Above, for example, the explorers have befriended a young moose along the Athabasca River in Alberta. Tyrrell's teams helped fill in maps of the region, brought back a trove of geological specimens, and gathered valuable anthropological data, such as the first photographs of the Caribou Inuit. The site includes a biography of Tyrrell, who is also known for discovering rich dinosaur deposits.

  3. DATABASE: The Dirt on Pollution

    Last month, when the Bush Administration proposed relaxing clean-air rules for power plants, nine Northeastern states filed suit, charging that the changes would exacerbate asthma and other respiratory diseases. The link between human illness and pollution remains a battleground. Researchers probing the connection can find county-by-county and state-by-state breakdowns of emissions at The 3-year-old site, created by Environmental Defense, reflects the advocacy group's green agenda, but it's also a rich vein of raw information. Its databases merge figures from the Environmental Protection Agency, the Department of Agriculture, state regulatory agencies, and other sources.

    Reports for each state provide data in eight categories, including lead exposure, levels of harmful air pollutants, release of toxic chemicals from industries, watershed health, and animal waste. County reports detail annual releases of toxic chemicals by individual plants and the location of Superfund sites. The site also profiles health effects and uses of more than 6900 hazardous chemicals, from antimony to zirconium.

  4. DATABASE: The Unbearable Lightness of Zero g

    In space, an astronaut's chest puffs up—not because of pride in the mission but because body fluids that would sink into the limbs on Earth linger in the torso instead. For more than 3 decades, scientists have been weighing the effects of reduced gravity on everything from blood circulation to the growth of crystals to the activation of the immune system's T cells. Find out what they've learned at the European Space Agency's Microgravity Database, which describes hundreds of physical and life science experiments carried out in space or in earthly simulators of low gravity. The studies come mainly from American, Russian, Soviet, and European space launches. Entries summarize the methods and results of each experiment, provide references, and often include original figures from publications and author contact information.