François Peaudecerf

Taylor's swimmers

2016/2017

With the help of the wonderful workshop team at DAMTP (University of Cambridge), we recreated the mechanical swimmers used by G. I. Taylor in his famous demonstration of the difference between high and low Reynolds number swimming (more details on the original swimmers below).

I used these replica in demonstrations for undergraduate students as part of the the course "Laboratory Demonstrations in Fluids Dynamics" at DAMTP.

The following video demonstrates the swimming behaviours of these replica models in water and golden syrup: play video

G. I. Taylor and the physics of swimming

2016

With my collaborator Ottavio Croze, we wrote an article entitled "G. I. Taylor and the physics of swimming" for the magazine of the Cavendish Laboratory (Physics Department of the University of Cambridge) about the pioneer work of G. I. Taylor on microbe motility and its impact on biophysics today.

Pictures of the original mechanical swimmers used by Taylor illustrate this article, in which we explain the fundamental difference between swimming at low and high Reynolds number.

Science Festival Open Day at DAMTP

2013/2015/2017

Every two years, the Department of Applied Maths and Theoretical Physics organises a lab open day during the Science Festival of the University of Cambridge. For each of them, I contributed demonstrations with micro-organisms.

In 2013, we designed with Dr. Kirsty Wan (middle photo, left) a dark chamber to observe the luminescent bacterium Photobacterium phosphoreum glowing, and discover the role of oxygen in luminescence. We also painted these bacteria on agar plates (top picture), and demonstrated phototaxis (the behavior of chasing light) in Chlamydomonas reihnardtii, a single-celled microalga.

In 2015, we set up a microscope above a small puddle of Volvox globator, a swimming colonial alga of around 1 mm diameter, to demonstrate their phototaxis live, by having them run from one end of the field of view to the opposite end when switching light position (bottom photo).

In 2017, I improved the design of this last demonstration set-up, by installing 4 LEDs, one on each side of a square arena, which could be activated by kids with a remote control, allowing them to choose the light signal they wanted to impose. To see Volvox in action, check the video: play video

Slime mold solving the maze

2012

During the summer of 2012, I recorded time-lapse videos of Physarum polycephalum, also called the "true slime mold", solving a maze, inspired by the work of Prof. Nakagaki et al. This organism grows in networks of bright yellow veins inside a plastic maze laid on top of an agar plate, and ends up reorganising itself to connect food sources - in that case oatflakes - through the shortest path possible, thus solving the maze. The video was made for the program NOVA ScienceNOW "What are animals thinking?" aired on November 7th 2012 on PBS, and was an outreach effort together with my slime mold collaborators Prof. Michael Brenner, Anne Pringle, Karen Alim and Gabriel Amselem. To see Physarum in action, check the video: play video