Watt Watt The watt (symbol: W) is a unit of power. In the International System of Units (SI) it is defined as a derived unit of 1 joule per second, and is used to quantify the rate of energy transfer. When an object's velocity is held constant at one meter per second against a constant opposing force of one newton, the rate at which work is done is 1 watt. In terms of electromagnetism, one watt is the rate at which electrical work is performed when a current of one ampere (A) flows across an electrical potential difference of one volt
Transepithelial potential difference Transepithelial potential difference Transepithelial potential difference (TEPD) is the voltage across an epithelium, and is the sum of the membrane potentials for the outer and inner cell membranes. The diagnosis of Cystic Fibrosis (CF) is usually based on high sweat chloride concentrations, characteristic clinical findings (including sinopulmonary infections), and/or family history. However, a small portion of patients with Cystic Fibrosis especially those with "mild" mutations of the Cystic Fibrosis Transmembrane Regulator ion channel (CFTR), have near-normal sweat tests. In these cases, a useful diagnostic, adjunct involves measuring the nasal transepithelial potential difference (ie, the charge on the respiratory epithelial surface