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.
Sinusitis Symptoms & Diagnosis. Sinusitis symptoms, whether acute or chronic, frequently develop after a cold or during times of severe or ongoing allergic rhinitis symptoms. The most obvious sign of sinusitis is a painful pressure in the cheeks and forehead. In cases of acute sinusitis, a fever may develop.