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Did you know?

Your skin wrinkles if you stay in the bathtub a long time because the outermost layer of skin (which consists of dead keratin) swells when it absorbs water. It is tightly attached to the skin below it, so it compensates for the increased area by wrinkling. This happens to the hands and feet because they have the thickest layer of dead keratin cells.

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There can actually be a 25-hour time difference between certain locations in the world. The International Date Line passes between the islands of Samoa and American Samoa. It is not a straight line, but "zig-zags" around various island chains. Therefore, Samoa and nearby islands have one date, while American Samoa and nearby islands are one day behind. Daylight saving time is used in some islands, but not in others—further shifting the hours out of sync with natural time.

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The average older adult in the United States takes five prescription drugs per day. Half of these drugs contain a sedative. Alcohol should therefore be avoided by most senior citizens because of the dangerous interactions between alcohol and sedatives.

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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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Asthma attacks and symptoms usually get started by specific triggers (such as viruses, allergies, gases, and air particles). You should talk to your doctor about these triggers and find ways to avoid or get rid of them.

True-color view of Mars seen through NASA's Hubble Space Telescope in 1999 True-color view of Mars seen through NASA's Hubble Space Telescope in 1999
Cystoscopy. In this procedure, a specialized endoscope with a rigid tube, known as a cystoscope, is Cystoscopy. In this procedure, a specialized endoscope with a rigid tube, known as a cystoscope, is
This engraving by William Russell Birch shows Congress Hall (left), which was occupied by Congress f This engraving by William Russell Birch shows Congress Hall (left), which was occupied by Congress f
Selected skeletal muscles (anterior view). Selected skeletal muscles (anterior view).
Raster is the best scope position to view the spark lines of all the cylinders to check for ... Raster is the best scope position to view the spark lines of all the cylinders to check for ...
Magnified view of the retina as seen through the pupil Magnified view of the retina as seen through the pupil
Video: Frequency of stimulation and force (Recruitment of motor units and force)

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