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.
1 The most common symptoms of Zika are fever, rash, joint pain, or red eyes. 2  Other symptoms include muscle pain, headache, pain behind the eyes, and vomiting.ymptoms. 1  About 1 in 5 people infected with Zika virus become ill (i.e., develop Zika). 2  The most common symptoms of Zika are fever, rash, joint pain, or red eyes. 3  The illness is usually mild with symptoms lasting for several days to a week. 4  Severe disease requiring hospitalization is uncommon. 5  Deaths due to Zika have not been reported.