Laboratoire Interdisciplinaire de Physique

Underwater spherical bubbles are good acoustic resonators but are notoriously difficult to stabilize. Here, to circumvent these limitations researchers from LIPhy trapped bubbles within 3D-manufactured millimetric open frames having the shape of the five Platonic solids with identical faces (4 to 20 faces). We thus obtained « Platonic bubbles », stabilized during several days. We measured their acoustic vibration under driving, and we observe that their resonance frequency obeys a simple formula in spite of the shape complexity.

How to measure objects that cannot be seen under normal circumstances? There is a way to modify the beam of a laser so that it provides exactly the information desired despite the presence of an environment that can be complex and messy. Moreover, this procedure does not work in an approximate way, but in an optimal way in the physical sense of the term: nature does not allow for better measuring accuracy with the coherent light of a laser.

The action potential is the fundamental signal of neuronal cells. In mammalian neurons, this signal is generated in the initial segment of the axon by a fast sodium current mediated by voltage-gated sodium channels. Luiza Filipis and Marco Canepari have developed a unique method allowing the measurement of the sodium current in the axon initial segment during the action potential generation. This novel technique opens the gate to the full understanding of neuronal excitation and to the investigation of genetic diseases caused by neuronal excitability dysfunction.