  We present calculations of nuclear-spin-dependent and
nuclear-spin-independent parity violating amplitudes in Ba, Ra, Ac+, Th and Pa.
Parity nonconservation in these systems is greatly enhanced due to the presence
of very close electronic energy levels of opposite parity, large nuclear
charge, and strong nuclear enhancement of parity-violating effects. The
presented amplitudes constitute several of the largest atomic parity-violating
signals predicted so far. Experiments using these systems may be performed to
determine values for the nuclear anapole moment, a P-odd T-even nuclear moment
given rise to by parity-violating nuclear forces. Such measurements may prove
to be valuable tools in the study of parity violation in the hadron sector. The
considered spin-independent transitions could also be used to measure the ratio
of weak charges for different isotopes of the same atom, the results of which
would serve as a test of the standard model and also of neutron distributions.
Barium, with seven stable isotopes, is particularly promising in this regard.
