The densities of vortex lines in He II due to rotation and axial counterflow do not simply add. With slow rotation, the critical counterflow velocity is greatly reduced. At high counterflow velocities, rotation adds fewer lines than expected, suggesting that the vortex tangle is polarized by rotation. Two critical velocities are found, the smaller of which agrees quantitatively with an explanation by Glaberson, Johnson, and Ostermeier of an instability found by Cheng, Cromar, and Donnelly.

We present a review of quantum turbulence, that is, the turbulent motion of quantized vortex lines in superfluid helium. Our discussion concentrates on the turbulence produced by steady, uniform heat flow in a pipe, but touches on other turbulent flows as well. We have attempted to motivate the study of quantum turbulence and discuss briefly its connection with classical turbulence. We include background on the two-fluid model and mutual friction theory, examples of modern experimental techniques, and a brief survey of the phenomenology. We discuss the important recent insights that vortex dynamics has provided to the understanding of quantum turbulence, from simple scaling arguments to detailed numerical simulations. We conclude with a discussion of open questions in this field.

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Vowel discrimination and perception were studied for a soprano singing on a fundamental frequency between 262 and 1047 Hz. The vowels were identified by 28 listeners as 1 of 12 American English vowels. As expected, both the singer's apparent first formant and the difficulty in vowel recognition increased as the fundamental frequency increased. Although some formant frequency shift can be tolerated without changing vowel perception, the greater shifts that occurred here contributed to the difficulty in understanding in a roughly predictable way.