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.
What are common TBI symptoms? TBI symptoms vary depending on the extent of the injury and the area of the brain affected. Some symptoms appear immediately; others may appear several days or even weeks later. A person with TBI may or may not lose consciousnessâloss of consciousness is not always a sign of severe TBI.