Astigmatism is the most common vision problem. It may accompany nearsightedness or farsightedness. It is usually caused by an irregularly shaped cornea, but sometimes it is the result of an irregularly shaped lens. Either type can be corrected by eyeglasses, contact lenses, or refractive surgery.
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In 1844, Charles Goodyear obtained the first patent for a rubber condom.
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Colchicine is a highly poisonous alkaloid originally extracted from a type of saffron plant that is used mainly to treat gout.
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Drying your hands with a paper towel will reduce the bacterial count on your hands by 45–60%.
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Normal urine is sterile. It contains fluids, salts, and waste products. It is free of bacteria, viruses, and fungi.
Apparent and True Orbits of Alpha Centauri.
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Isotopes of Hydrogen
Which of the following statements is true of linkage?