A study of the//-decay of 98y and of the level scheme of 98Zr was undertaken by the use of the two recoil fission product separators JOSEF and LOHENGRIN. Two //-decay modes have been detected for 98y, the half-lives of which are 0.65_+ 0.05 s and 2.0_+ 0.2 s. The spins and parities of the two states which undergo//-decay are proposed to be 1 § and 4-, respectively, with the configurations (~ l g9/2)(v l g~/2) and (~2pl/2) (v lg7/2). The measured Qp-value is 7300• for the 0.65s decay. The level scheme of 98Zr was deduced from 7,7-coincidence data. Absolute 7-intensities were obtained from two independent measurements. The half-life of the first excited state of 98Zr at 853.0keV with spin and parity 0 § was determined through delayed 7,e--measurements to be 63 _+Tns. No indication of the coexistence of two different nuclear shapes of 98Zr was found.

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The /?-decay of lOOy has been investigated at the gas filled recoil separator JOSEF by means of 7-ray and conversion electron spectroscopy. Two B-decay modes, of half lives 0.94 + 0.03 s and 0.55 _+ 0.15 s, have been observed. Using XV-, Xce-, V7-and 7ce-coincidences the level scheme of ~~176 has been constructed. An excited 0~-state at 331.3 keV has been discovered in this nucleus. The/~-decay from the 0.55 s decay mode in 10oy shows a strong preference for the ground state compared to the 0~-state in ~~176 The structure of l~176 and the nature of the 0~ level is discussed in the light of the present results.

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Fluorescence in situ hybridization (FISH) with alpha-satellite DNA probes was used to study whole-arm chromosome translocation products in a family in which the propositus was shown to have a monosomy 18p/trisomy 20p imbalance. By this approach, we show that the chromosome 18 alpha-satellite DNA block is split into 2 smaller units, whereas the chromosome 20 breakpoint is not included within the alpha-satellite DNA region. We found no evidence to suggest that this split alpha-satellite DNA region has reduced or impaired the function of the centromere or that it contributed to the phenotype of the propositus. The FISH technique critically demonstrated the involvement of a whole-arm translocation in this case and provided accurate identification of breakpoints, which was not possible with standard banding techniques.