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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.
When Gabriel Fahrenheit invented the first mercury thermometer, he called "zero degrees" the lowest temperature he was able to attain with a mixture of ice and salt. For the upper point of his scale, he used 96°, which he measured as normal human body temperature (we know it to be 98.6° today because of more accurate thermometers).
Most childhood vaccines are 90–99% effective in preventing disease. Side effects are rarely serious.
Cytomegalovirus affects nearly the same amount of newborns every year as Down syndrome.
Fewer than 10% of babies are born on their exact due dates, 50% are born within 1 week of the due date, and 90% are born within 2 weeks of the date.