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.
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More than one-third of adult Americans are obese. Diseases that kill the largest number of people annually, such as heart disease, cancer, diabetes, stroke, and hypertension, can be attributed to diet.
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Blood is approximately twice as thick as water because of the cells and other components found in it.
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Since 1988, the CDC has reported a 99% reduction in bacterial meningitis caused by Haemophilus influenzae, due to the introduction of the vaccine against it.
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There are 60,000 miles of blood vessels in every adult human.
Variation in shape and length of nerve cells.
Red Blood Cells
Connective tissue cells
The thymus, a primary lymphoid organ where T cells mature.
A late stage in mitosis after the chromosomes (stained blue) have separated