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# The mathematics of a good espresso, a mummy speaks after 3000 years, volcano turns human brain to glass

24 Jan 2020 Hamish Johnston

Cup-to-cup consistency is a problem for people using espresso machines, according to Jamie Foster who is a mathematician at the University of Portsmouth. One cup can taste lovely and the next not so nice – even when the machine is operated by a skilled barista.

In a quest for a consistently good cup of coffee, Foster and an international team of researchers have created a model that describes how hot water is forced through coffee grounds in an expresso machine.  By looking at the process for different grinds of coffee, they discovered that there is an optimum size for the coffee grounds. Espresso coffee normally comes in a fine grind, which maximizes the surface area of coffee that is in contact with the water. In theory, this should result in a strong cup of coffee that gets the most flavour out of the grounds.

However, Foster and colleagues’ calculations reveal that if the coffee is too fine, the water can be prevented from reaching all of the coffee – resulting in a poor cup. The model revealed an optimum size for the coffee grounds and the solution is currently being tested in a coffee shop in the US.

I was listening to the radio on the way home yesterday and there was an interesting interview with David Howard of Royal Holloway, University of London who was part of a team that reconstructed the vocal tract of a 3000-year-old Egyptian mummy. The shape of the vocal tract was determined using CT scans and it was rebuilt using a 3D printer.

The vocal tract was connected to an artificial larynx and the team was able to generate a sound a bit like the bleating of a sheep. They were unable to create more complex sounds because that would require further components such as the mummy’s tongue, which was too shrivelled to recreate.

You can read more about the mummy and listen to a clip of the mummy’s voice in this BBC article.

Staying in the ancient world, Pier Paola Petrone, a forensic anthropologist at the University of Naples Federico II, and colleagues have identified the remains of a human brain that was turned to glass during the famous eruption of the volcano Vesuvius in 79 AD. The remains were found in Herculaneum, which was buried under hot volcanic ash. The brain of the victim – who was in his 20s – was rapidly burned inside the skull and then cooled rapidly to form glass in a process called vitrification.

You can see photographs of the black, shiny glass in “Mount Vesuvius eruption: Extreme heat ‘turned man’s brain to glass’”.