Medium effects as a function of the mass number A are studied in the total
photonuclear cross section from the Δ-resonance region up to the region
where shadowing effects are known to exist. A consistent picture is obtained by
simply assuming a density dependence of the different mechanisms of resonance
broadening and shadowing. The Δ-mass shift is found to increase with
A.Comment: 7 pages, LaTeX, 2 figures available from the author