Did you know?
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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Excessive alcohol use costs the country approximately $235 billion every year.
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Though the United States has largely rejected the metric system, it is used for currency, as in 100 pennies = 1 dollar. Previously, the British currency system was used, with measurements such as 12 pence to the shilling, and 20 shillings to the pound.
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A cataract is a clouding of the eyes' natural lens. As we age, some clouding of the lens may occur. The first sign of a cataract is usually blurry vision. Although glasses and other visual aids may at first help a person with cataracts, surgery may become inevitable. Cataract surgery is very successful in restoring vision, and it is the most frequently performed surgery in the United States.
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HIV testing reach is still limited. An estimated 40% of people with HIV (more than 14 million) remain undiagnosed and do not know their infection status.
Countercurrent heat exchange in the lateral muscles of bluefin tuna.
Mass Exchange Between Close Binary Stars
Despite the traditional focus on males, females actively choose mates and are the driving force in t
Xenophon (430–357 B.C.E.) Biographer of Socrates and his student as a youth. In addition to four ...
Soils support plant growth through ion exchange
Exchange of Oxygen and Carbon Dioxide