Lifetimes of yrast and near-yrast states of<mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" display="inline"><mml:mrow><mml:mmultiscripts><mml:mrow/><mml:mprescripts/><mml:mrow/><mml:mrow><mml:mn>159</mml:mn></mml:mrow><mml:mrow/><mml:mrow/></mml:mmultiscripts></mml:mrow></mml:math>,<i>160</i>,<i>161</i>Yb

Lifetimes of high-spin states of $^{159}$,160,161Yb, populated by fusion-evaporation reactions, have been measured by the recoil-distance technique. The data were collected in coincidence with a total-energy filter to provide some discrimination on reaction channel. The principal feature of the resulting transition quadrupole moments is a frequency-dependent reduction which is displayed by those bands with aligned quasiparticles. This seems to be mainly due to the influence of the favored ${i}_{13/2}$ quasineutron. Additional available data are surveyed and support this conclusion. Calculations using the cranked shell model and the cranked Hartree-Fock-Bogoliubov and cranked Nilsson-Strutinsky methods provide a qualitative description of the experimental observations. In addition, a satisfactory account is provided by recent calculations based on a fermion dynamical-symmetry model.

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