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The horizontal fraction bar was introduced by the Arabs.
Your skin wrinkles if you stay in the bathtub a long time because the outermost layer of skin (which consists of dead keratin) swells when it absorbs water. It is tightly attached to the skin below it, so it compensates for the increased area by wrinkling. This happens to the hands and feet because they have the thickest layer of dead keratin cells.
Every 10 seconds, a person in the United States goes to the emergency room complaining of head pain. About 1.2 million visits are for acute migraine attacks.
According to the FDA, adverse drug events harmed or killed approximately 1,200,000 people in the United States in the year 2015.
For about 100 years, scientists thought that peptic ulcers were caused by stress, spicy food, and alcohol. Later, researchers added stomach acid to the list of causes and began treating ulcers with antacids. Now it is known that peptic ulcers are predominantly caused by Helicobacter pylori, a spiral-shaped bacterium that normally exist in the stomach.
![The wolf spider, Lycosa godeffroyi, is common in many areas of Australia. In this family of spiders,](https://biology-forums.com/gallery/47/medium_27605_22_04_12_6_41_34.jpeg)
![The “Big Four” world leaders meet at the Hotel Crillon in Paris, 1919. From left to right (front row](https://biology-forums.com/gallery/47/medium_4_23_06_16_8_41_01_236271811.jpeg)