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Pope Sylvester II tried to introduce Arabic numbers into Europe between the years 999 and 1003, but their use did not catch on for a few more centuries, and Roman numerals continued to be the primary number system.
More than 20 million Americans cite use of marijuana within the past 30 days, according to the National Survey on Drug Use and Health (NSDUH). More than 8 million admit to using it almost every day.
According to the National Institute of Environmental Health Sciences, lung disease is the third leading killer in the United States, responsible for one in seven deaths. It is the leading cause of death among infants under the age of one year.
Multiple sclerosis is a condition wherein the body's nervous system is weakened by an autoimmune reaction that attacks the myelin sheaths of neurons.
IgA antibodies protect body surfaces exposed to outside foreign substances. IgG antibodies are found in all body fluids. IgM antibodies are the first type of antibody made in response to an infection. IgE antibody levels are often high in people with allergies. IgD antibodies are found in tissues lining the abdomen and chest.