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Did you know?

Each year in the United States, there are approximately six million pregnancies. This means that at any one time, about 4% of women in the United States are pregnant.

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Autoimmune diseases occur when the immune system destroys its own healthy tissues. When this occurs, white blood cells cannot distinguish between pathogens and normal cells.

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After a vasectomy, it takes about 12 ejaculations to clear out sperm that were already beyond the blocked area.

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Certain chemicals, after ingestion, can be converted by the body into cyanide. Most of these chemicals have been removed from the market, but some old nail polish remover, solvents, and plastics manufacturing solutions can contain these substances.

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There used to be a metric calendar, as well as metric clocks. The metric calendar, or "French Republican Calendar" divided the year into 12 months, but each month was divided into three 10-day weeks. Each day had 10 decimal hours. Each hour had 100 decimal minutes. Due to lack of popularity, the metric clocks and calendars were ended in 1795, three years after they had been first marketed.

A fixed action pattern elicited by a sign stimulus. A fixed action pattern elicited by a sign stimulus.
Measles. A photograph of a child stricken with measles, showing the tell-tale sign of the skin rash. Measles. A photograph of a child stricken with measles, showing the tell-tale sign of the skin rash.
Human embryonic stem cells forming rosettes, a sign of neural differentiation Human embryonic stem cells forming rosettes, a sign of neural differentiation
Head binding, or artificial deformation, was used by some populations as a sign of identity. Head binding, or artificial deformation, was used by some populations as a sign of identity.
Testing for the bulge sign Testing for the bulge sign
Both Chvostek sign, A, and Trousseau sign, when positive, B Both Chvostek sign, A, and Trousseau sign, when positive, B
Video: Stomach peristalsis & Enterogastric reflex

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