2026-07-072026-07-07http://salesiana.dossiersoluciones.com/handle/123456789/213970Dynamic degrees of freedom and internal variables are treated in a uniform way. The unification is achieved by means of the introduction of a dual internal variable. This duality provides the corresponding evolution equations depending on whether the Onsager-Casimir reciprocity relations are satisfied or not.16 pages, revisedOther Condensed Mattertext