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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.
During the twentieth century, a variant of the metric system was used in Russia and France in which the base unit of mass was the tonne. Instead of kilograms, this system used millitonnes (mt).
Bacteria have flourished on the earth for over three billion years. They were the first life forms on the planet.
Your heart beats over 36 million times a year.
Most childhood vaccines are 90–99% effective in preventing disease. Side effects are rarely serious.