Akademik

1. Failure of either one of two related phenomena to keep pace with the other; or any situation in which the value of one depends upon whether the other has been increasing or decreasing. 2. The lag of a magnetic effect behind its cause. SYN: magnetic inertia. 3. The temperature differential that exists when a substance, such as reversible hydrocolloid, melts at one temperature and solidifies at another. 4. The basis of a type of cooperativity observed in many enzyme-catalyzed reactions in which the degree of cooperativity is associated with a slow conformational change of the enzyme. Cf.:allosterism, cooperativity. [G. h., a coming later]

- static h. the difference in the value reached by a dependent variable at a particular constant value of the independent variable, depending on whether the latter value had been approached from above or below; e.g., in measuring the pressure volume relations of the lungs, if one completely expires and then inspires to a particular volume and holds it constant, the transpulmonary pressure required to maintain that lung volume is greater than if one had completely inspired and then expired to the same volume and held it constant.

hys·ter·e·sis .his-tə-'rē-səs n, pl -e·ses -.sēz

1) the lagging of a physical effect on a body behind its cause (as behind changed forces and conditions) <all manometers must be tested for \hysteresis as well as for sensitivity and natural frequency (H. D. Green)>

2 a) the influence of the previous history or treatment of a body on its subsequent response to a given force or changed condition <a study has been made of the phenomenon of rennet \hysteresis, in which the time of coagulation of heated milk is progressively greater with increase in the time interval between heating and addition of rennet (J. S. Fruton)>

b) the changed response of a body that results from this influence