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The first-known contraceptive was crocodile dung, used in Egypt in 2000 BC. Condoms were also reportedly used, made of animal bladders or intestines.

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Fungal nail infections account for up to 30% of all skin infections. They affect 5% of the general population—mostly people over the age of 70.

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Vampire bats have a natural anticoagulant in their saliva that permits continuous bleeding after they painlessly open a wound with their incisors. This capillary blood does not cause any significant blood loss to their victims.

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Less than one of every three adults with high LDL cholesterol has the condition under control. Only 48.1% with the condition are being treated for it.

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Illness; diuretics; laxative abuse; hot weather; exercise; sweating; caffeine; alcoholic beverages; starvation diets; inadequate carbohydrate consumption; and diets high in protein, salt, or fiber can cause people to become dehydrated.

The Sun in false-color ultraviolet image The Sun in false-color ultraviolet image
Light rays coming from an object to the retina. Light rays coming from an object to the retina.
Spot the hidden object Spot the hidden object
Triumphal Entry, page from a manuscript of Firdawsi's Shahnamah, Persian, Safavid culture. Triumphal Entry, page from a manuscript of Firdawsi's Shahnamah, Persian, Safavid culture.
Do you know what that large object in the center of the photo is? In the 1920s, 30s, and 40s, ... Do you know what that large object in the center of the photo is? In the 1920s, 30s, and 40s, ...
Video: T cell receptors

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