I just found, on my desktop, a PDF of a paper called "Multivariate analysis of beer foam stand". I have no idea where it came from.......
<p>it was 30 years ago, but I knew people in the Heriot Watt school of microbiology who specialized in brewing (youngers/tennants/mcewans paid for it I think) and did research on this kind of thing, and on why some glasses keep a foam trail and others don't.</p><p> maybe something dropped out of a time-hole, or one of those foam beer widgets in the bottom of a can of Guinness (which is clearly a beer-centric manifold like L-Space in discworld) <br /></p>
George Michaelson