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Pregnant women usually experience a heightened sense of smell beginning late in the first trimester. Some experts call this the body's way of protecting a pregnant woman from foods that are unsafe for the fetus.
The Romans did not use numerals to indicate fractions but instead used words to indicate parts of a whole.
Vaccines prevent between 2.5 and 4 million deaths every year.
There are major differences in the metabolism of morphine and the illegal drug heroin. Morphine mostly produces its CNS effects through m-receptors, and at k- and d-receptors. Heroin has a slight affinity for opiate receptors. Most of its actions are due to metabolism to active metabolites (6-acetylmorphine, morphine, and morphine-6-glucuronide).
Cancer has been around as long as humankind, but only in the second half of the twentieth century did the number of cancer cases explode.