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Multiple experimental evidences have confirmed that at the molecular level, cancer is caused by lesions in cellular DNA.
The horizontal fraction bar was introduced by the Arabs.
The shortest mature adult human of whom there is independent evidence was Gul Mohammed in India. In 1990, he was measured in New Delhi and stood 22.5 inches tall.
Most childhood vaccines are 90–99% effective in preventing disease. Side effects are rarely serious.
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.