Recent experiments have demonstrated that the rotational-alignment for the
N=Z nuclei in the mass-80 region is considerably delayed as compared to the
neighboring N=Z nuclei. We investigate whether this observation can be
understood by a known component of nuclear residual interactions. It is shown
that the quadrupole-pairing interaction, which explains many of the delays
known in rare-earth nuclei, does not produce the substantial delay observed for
these N=Z nuclei. However, the residual neutron-proton interaction which is
conjectured to be relevant for N=Z nuclei is shown to be quite important in
explaining the new experimental data.Comment: 4 pages, 3 figures, final version accepted by Phys. Rev. C as a Rapid
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