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Pope Sylvester II tried to introduce Arabic numbers into Europe between the years 999 and 1003, but their use did not catch on for a few more centuries, and Roman numerals continued to be the primary number system.
Multiple experimental evidences have confirmed that at the molecular level, cancer is caused by lesions in cellular DNA.
Inotropic therapy does not have a role in the treatment of most heart failure patients. These drugs can make patients feel and function better but usually do not lengthen the predicted length of their lives.
Ether was used widely for surgeries but became less popular because of its flammability and its tendency to cause vomiting. In England, it was quickly replaced by chloroform, but this agent caused many deaths and lost popularity.
When blood is exposed to air, it clots. Heparin allows the blood to come in direct contact with air without clotting.