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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.
The term bacteria was devised in the 19th century by German biologist Ferdinand Cohn. He based it on the Greek word "bakterion" meaning a small rod or staff. Cohn is considered to be the father of modern bacteriology.
The modern decimal position system was the invention of the Hindus (around 800 AD), involving the placing of numerals to indicate their value (units, tens, hundreds, and so on).
More than 2,500 barbiturates have been synthesized. At the height of their popularity, about 50 were marketed for human use.
The top 10 most important tips that will help you grow old gracefully include (1) quit smoking, (2) keep your weight down, (3) take supplements, (4) skip a meal each day or fast 1 day per week, (5) get a pet, (6) get medical help for chronic pain, (7) walk regularly, (8) reduce arguments, (9) put live plants in your living space, and (10) do some weight training.