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 the symptoms of Zika? About 80% of people who are infected with Zika virus do not become sick. For the 20% who do become sick, the most common symptoms include fever, rash, joint pain, and conjunctivitis (red eyes). The illness is usually mild and the symptoms typically last several days to a week.