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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).
Acute bronchitis is an inflammation of the breathing tubes (bronchi), which causes increased mucus production and other changes. It is usually caused by bacteria or viruses, can be serious in people who have pulmonary or cardiac diseases, and can lead to pneumonia.
Vaccines prevent between 2.5 and 4 million deaths every year.
In the United States, there is a birth every 8 seconds, according to the U.S. Census Bureau's Population Clock.
The first documented use of surgical anesthesia in the United States was in Connecticut in 1844.