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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.
Hyperthyroidism leads to an increased rate of metabolism and affects about 1% of women but only 0.1% of men. For most people, this increased metabolic rate causes the thyroid gland to become enlarged (known as a goiter).
Alzheimer's disease affects only about 10% of people older than 65 years of age. Most forms of decreased mental function and dementia are caused by disuse (letting the mind get lazy).
Most strokes are caused when blood clots move to a blood vessel in the brain and block blood flow to that area. Thrombolytic therapy can be used to dissolve the clot quickly. If given within 3 hours of the first stroke symptoms, this therapy can help limit stroke damage and disability.
The Romans did not use numerals to indicate fractions but instead used words to indicate parts of a whole.