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The coefficient $A$ has dimensions of electric current density divided by squared temperature. For ideal nonrelativistic particles with the free electron mass, two spin states, a planar uniform surface, and unit escape transmission, the thermionic tail-flux derivation giveswhere $e$ is the positive elementary charge and $h$ is the Planck constant. The two area units differ by a factor of $10^4$. A fitted $A$ need not equal $A_0$: reflection at the surface, the electronic band structure, and uncertain emitting area affect the inferred coefficient. A constant escape transmission $\tau$ would give $A=\tau A_0$ in this simple model; an energy-dependent transmission generally requires an integral instead.

The name joins Owen Willans Richardson with Saul Dushman. Dushman's 1923 paper develops a thermodynamic treatment of electron emission analogous to evaporation and evaluates the prefactor using quantum ideas.^[ref]

Thermoregulation regulates body temperature. Skin signals can anticipate a change of core body temperature, so a response need not wait for an internal error. ^[ref]

These responses have costs and environmental limits. Shivering consumes metabolic resources; cooling through sweating removes water that must eventually be replaced. High humidity restricts evaporation, so secreted sweat and successful cooling are not interchangeable. Maintaining core body temperature also depends on maintaining circulation: depleted blood volume can compromise skin blood flow and heat transfer. Seeking shade or reducing work changes the disturbance itself, whereas a larger regulatory command merely attempts to counter it. ^[ref]

Vaporization changes a liquid into a gas. It includes evaporation at a surface and boiling within the liquid. Below the liquid-gas critical point, equilibrium conversion along the liquid-vapour phase coexistence curve involves latent heat; the liquid and vapour have equal chemical potential there.