Darwinism designates a distinctive form of evolutionary explanation for the history and diversity of life on earth. Its original formulation is provided in the first edition of On the Origin of Species in 1859.
The enthalpy - or internal energy - of a substance is a function of its temperature and pressure. The change in internal energy with respect to change in temperature at fixed pressure is the Specific Heat at constant pressure - cp.
You can find more details in the wiki article on Gibbs free energy and it's associated links. H is the symbol for enthalpy, a measure of how much energy an average particle in a system has. S is the symbol for entropy, a measure of the disorder of the particles in a system. Related Questions.