Unlike conventional crystals, quasicrystals are predicted to be elastically isotropic. To confirm this prediction experimentally, one must distinguish the quasicrystal from nearly isotropic crystals, which requires a high degree of precision. We report the use of resonant ultrasound spectroscopy to determine that the A1CuLi quasicrystal is isotropic within 0.07%, significantly more isotropic than any conventional crystal (by 10 standard deviations). By contrast, we find that a closely related cubic phase of A1CuLi is slightly, but measurably, anisotropic.

Five pleomorphic, one monomorphic adenoma and one acinic cell lower pole parotid tumours were thought to be lymph nodes and enucleated. Wide excision of the operative site within 2 months revealed microscopic recurrence in three cases. Three carcinomas were enucleated and two had recurred rapidly. It is suggested that such cases of inadvertent enucleation should undergo wide resection of the operative site with nerve dissection.

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We have made measurements of the layer-by-layer growth of solid "^He from the superfluid onto a graphite substrate, and at temperatures below 0.95 K and up to eight layers we have observed remarkable and unexpected behavior which gives clear evidence of a two-stage layering transition. It is speculated that the two stages may result from the different binding energies at step and kink sites (possibly involving quantum kinks) or an incommensurate-commensurate transition.