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Adult head lice are gray, about ? inch long, and often have a tiny dot on their backs. A female can lay between 50 and 150 eggs within the several weeks that she is alive. They feed on human blood.
Most childhood vaccines are 90–99% effective in preventing disease. Side effects are rarely serious.
Methicillin-resistant Staphylococcus aureus or MRSA was discovered in 1961 in the United Kingdom. It if often referred to as a superbug. MRSA infections cause more deaths in the United States every year than AIDS.
Normal urine is sterile. It contains fluids, salts, and waste products. It is free of bacteria, viruses, and fungi.
The Babylonians wrote numbers in a system that used 60 as the base value rather than the number 10. They did not have a symbol for "zero."