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The modern decimal position system was the invention of the Hindus (around 800 AD), involving the placing of numerals to indicate their value (units, tens, hundreds, and so on).
Bacteria have been found alive in a lake buried one half mile under ice in Antarctica.
Signs of depression include feeling sad most of the time for 2 weeks or longer; loss of interest in things normally enjoyed; lack of energy; sleep and appetite disturbances; weight changes; feelings of hopelessness, helplessness, or worthlessness; an inability to make decisions; and thoughts of death and suicide.
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.
Warfarin was developed as a consequence of the study of a strange bleeding disorder that suddenly occurred in cattle on the northern prairies of the United States in the early 1900s.