We detail the generalized theory as well as the long-term dynamics of the instabilities in the companion paper :
journals.aps.org/prfluids/abs...

Thanks to the brilliant Marco Vona, Eric Lauga and Takuji Ishikawa - and of course huge thanks to my advisors Raphaël and Nicolas!

A jet breaks into droplets that elongate into ellipses...in turn unstable to buckling, as soon as they are thin enough for one wavelength to develop. We end up with these structures that can also be understood through symmetry arguments - see this beautiful work: journals.aps.org/prl/abstract...

When C.reinhardtii cells swim one behind each other, they tend to pull on their neighbors, leading to a pearling instability. In contrast, when they swim side to side, they push on their neighbors, leading to a buckling instability. We control both by steering these phototactic cells with light.

See this nice summary in Physics Magazine (where I note an important difference between algae and penguins):
physics.aps.org/articles/v18...

A collaboration between physicists, biologists and chemists. Algae inside the dense phase are collectively protected from photodamage, showing that phototaxis can complement efficiently molecular photoprotective mechanisms on short timescales.

We show that the coupling between negative phototaxis and light absorption by the green algae destabilizes the suspension at critical cell densities/light intensities while the nonlocality of vision interactions explains the selection of a finite wavelength.

I was surprised that the Compagnie du Mt Blanc doesn't mention climate change in their ~2h exhibition on Mont Blanc massif and mountaineering at the Aiguille du Midi.
Yet the station is covered with sensors to anticipate rock falls and weakening of the structure due to the melting of permafrost.

And finally, a picture from Irene Joliot-Curie's album (from a small exhibition outside the Curie museum in Paris). She took it in 1939 also in Mont Blanc massif, at the summit of Mt Tondu. In 2023 the Glacier de Tré-la-Tête has hugely receded

I was surprised that the Compagnie du Mt Blanc doesn't mention climate change in their ~2h exhibition on Mont Blanc massif and mountaineering at the Aiguille du Midi.
Yet the station is covered with sensors to anticipate rock falls and weakening of the structure due to the melting of permafrost.

..and the Glacier d'Argentiere, that will soon no longer be visible from the village (another old picture displayed at the school)

Here is another view of the Glacier des Bossons that I paired with the current picture.

Another picture displayed in the school shows the Glacier des Bossons as seen from Chamonix a century ago.

wowww bravo Gianni! super happy for you!