2026-07-072026-07-07http://salesiana.dossiersoluciones.com/handle/123456789/29988A simple two-band model is suggested explaining recently reported unusual features for hopping magnetoresistance and the metal-insulator transition in 2D structures. The model implies that the conductivity is dominated by the upper Hubbard band (D^- band). Experimental studies of hopping magnetoresistance for Si delta doped GaAs/AlGaAs heterostructure give additional evidences for the model.13 pages, 3 gif-figuresMesoscale and Nanoscale PhysicsDisordered Systems and Neural Networkstext