Hi, dear all, Recently face some controversial issue with my supervisor and i cannot convince my self too. is it time varying elastance equal to time varying young modulus? Young modulus unit is Pa, however, elastance value is mmHg/ml, is both of them are equal? Young's modulus, also known as the tensile modulus, is a measure of the stiffness of an elastic material and is a quantity used to characterize materials. It is defined as the ratio of the uniaxial stress over the uniaxial strain in the range of stress in which Hooke's Law holds. http://en.wikipedia.org/wiki/Young's_modulus Compliance is calculated using the following equation, where ΔV is the change in volume, and ΔP is the change in pressure: http://en.wikipedia.org/wiki/Compliance_(physiology [Broken]) as in the engineering software like ansys, comsol, adina, we only can set young modulus, so i wondering whether they are the same?