  The theoretical evaluation of major nuclear structure effects on the
asymmetry of allowed Gamow-Teller beta-decay rates in light mirror nuclei is
presented. The calculations are performed within the shell model, using
empirical isospin-nonconserving interaction and realistic Woods-Saxon radial
wave functions. The revised treatment of p-shell nuclei is supplemented by
systematic calculations for sd-shell nuclei and compared to experimental
asymmetries when available. The results are important in connection with the
possible existence of second-class currents in the weak interaction.
