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Did you know?

An identified risk factor for osteoporosis is the intake of excessive amounts of vitamin A. Dietary intake of approximately double the recommended daily amount of vitamin A, by women, has been shown to reduce bone mineral density and increase the chances for hip fractures compared with women who consumed the recommended daily amount (or less) of vitamin A.

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The immune system needs 9.5 hours of sleep in total darkness to recharge completely.

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Bacteria have been found alive in a lake buried one half mile under ice in Antarctica.

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Parkinson's disease is both chronic and progressive. This means that it persists over a long period of time and that its symptoms grow worse over time.

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In 1885, the Lloyd Manufacturing Company of Albany, New York, promoted and sold "Cocaine Toothache Drops" at 15 cents per bottle! In 1914, the Harrison Narcotic Act brought the sale and distribution of this drug under federal control.

Drawing of French explorer Paul du Chaillu at close quarters with a gorilla Drawing of French explorer Paul du Chaillu at close quarters with a gorilla
An incentive spirometer An incentive spirometer
Chuck Close, Stanley II, detail. 1980–81. Chuck Close, Stanley II, detail. 1980–81.
Valves in veins open to permit blood flow, close to prevent backflow. Valves in veins open to permit blood flow, close to prevent backflow.
A close relationship between greenhouse gas emissions and a country’s gross domestic product A close relationship between greenhouse gas emissions and a country’s gross domestic product
Video: Definition of heart rate

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