2026-07-072026-07-07http://salesiana.dossiersoluciones.com/handle/123456789/194978Some models are presented in which the strength of the gravitational coupling of the potential energy relative to the same coupling for the kinetic energy is, in a precise sense, adjustable. The gauge symmetry of these models consists of those coordinate changes with unit jacobian.LaTeX, 23 pages, conclusions expanded. Two paragraphs and a new reference addedHigh Energy Physics - TheoryAstrophysicsGeneral Relativity and Quantum Cosmologytext