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Warfarin was developed as a consequence of the study of a strange bleeding disorder that suddenly occurred in cattle on the northern prairies of the United States in the early 1900s.
The Romans did not use numerals to indicate fractions but instead used words to indicate parts of a whole.
The first documented use of surgical anesthesia in the United States was in Connecticut in 1844.
Most childhood vaccines are 90–99% effective in preventing disease. Side effects are rarely serious.
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.