The earliest known work on the attached plane jet was carried out by Forthmann (1934), which was described and quoted by Sigalla (1958), Schwarz and Cosart (1961), Reddy Gorla and Jeng (1971), Bajura and Catalano (1975), Rajaratnam (1976), Awbi (1991), and Imao et al.
The Test Sample. Ammonia is a waste product formed primarily by bacteria in the intestines during the digestion of protein. If not processed and cleared from the body appropriately, excess ammonia can accumulate in the blood. This test measures the amount of ammonia in the blood. Ammonia is normally transported in the blood to the liver, where it is converted into two substances called urea and glutamine. The urea is then carried to the kidneys, where it is eliminated in the urine.
It measures the level of ammonia in your blood. When it is high it is not much fun. The explaination in Hector SF's post is so accurate. The first indication for me that it is high is that my hands shake and I can't write and it's hard to hold fork or spoon. I also get confused easily and can't sort things out.