One of the most important standards that the API has set is the method used for measuring the density of petroleum. This standard is called the API gravity. Specific gravity is a ratio of the density of one substance to the density of a reference substance, usually water.
The most common symptoms of RSI include: 1  Pain. 2  Tingling. 3  A feeling of restlessness in the joint. 4  Weakness. 5  Throbbing. 6  Stiffness or cramp.
Signs and symptoms of giardiasis can vary, and some people may be infected without showing any symptoms. Symptoms, when they occur, can last two weeks or longer. The most common symptoms are. 1  diarrhea, 2  gas, 3  fatty or foul-smelling stools (they may float), and.  stomach or abdominal cramping.