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.
RSV Symptoms, Causes & Risk Factors. RSV causes a wide variety of symptoms, ranging from very mild to life threatening. The type and severity of symptoms depend on multiple factors, including the particular strain of the virus and whether the patient has other underlying medical problems.