In the Hornbostel-Sachs classification system, it is a membranophone. Drums consist of at least one membrane, called a drumhead or drum skin, that is stretched over a shell and struck, either directly with the player's hands, or with a drum stick, to produce sound.
Heat production can be calculated from a measurement of VO 2 and/or CO 2. Doubly-Labeled Water Doubly-labeled water contains isotopes of oxygen and of hydrogen. The technique involves the consumption by the patient of the doubly-labeled water then the measurement of the amount of isotope in the person after a washout period of 7- 14 days. Most of the hydrogen and oxygen isotopes are lost through excretion and evaporation, but some of the oxygen isotope equilibrates with carbon dioxide and is expired in air.
Turbidity is measured in nephelometric turbidity units, or NTUs. Nephelometric simply means how cloudy the water is. The picture above shows different NTU values for samples of water. Drinking water must have less than 0.5 NTU, more clear then the beaker of water shown above with a 10 underneath.urbidity is a measure of how clear the water is. High turbidity means that there are a lot of particles suspended in the water and light cannot get through. Low turbidity means that there are fewer particles in the water and it is more clear. Turbidity in a stream may increase from: 1  soil erosion. 2  higher levels of algae.