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.
Symptoms of Common Variable Immunodeficiency. The list of signs and symptoms mentioned in various sources for Common Variable Immunodeficiency includes the 35 symptoms listed below: Recurring ear infections. Recurring sinus infections. Recurring lung infections. Pneumonia. Recurring bronchial infections. Gastrointestinal infections. Painful swollen joints.