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More than 2,500 barbiturates have been synthesized. At the height of their popularity, about 50 were marketed for human use.
The most common childhood diseases include croup, chickenpox, ear infections, flu, pneumonia, ringworm, respiratory syncytial virus, scabies, head lice, and asthma.
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 first documented use of surgical anesthesia in the United States was in Connecticut in 1844.
The Romans did not use numerals to indicate fractions but instead used words to indicate parts of a whole.