Come to PMMH laboratory: www.pmmh.espci.fr/Contact-357
Next Seminars
24 Avril : No seminar (Vacances de Pâques)
1 Mai : No seminar (Vacances de Pâques)
8 Mai : No seminar (Férié)
15 Mai : No seminar (Pont de l’Ascension)
22 Mai : Vava Gligorov (LPNHE, SU)
29 Mai : Jonathan Fouchard (IBPS)
Together, these results show how biological and physical processes can cooperate to enable and regulate developmental process.
On the theoretical front, by viewing self-organization as noisy encoding, we prove that the positional information capacity of short-range classical systems with discrete states is fundamentally limited, and show how this limit can be bypassed when long-range correlations are present.
which displays a remarkable bistability in outcome under molecular perturbations.
Using whole-organ live imaging, covariant measures of tissue dynamics, and mechanical modeling, we outline a ‘mechanical Waddington landscape’ framework to explain the global stability of chiral organ morphogenesis.
I present experimental and theoretical results highlighting how long-range physical constraints can explain the stability of emergent patterns. On the experimental front, we study the emergence of chiral symmetry breaking in the coiling of the embryonic fly midgut,
Modern imaging and genetic engineering allow for unprecedented access into the dynamics of biological self-organization, yet understanding how spatial organization emerges robustly remains challenging in these noisy, nonlinear living systems.
Dear colleagues,
The PMMH seminar on Friday 17 April at 11am will be given by Nicolas Romeo of the University of Chicago.
Title: Canalizing biological self-organization with physical constraints
Abstract below. Zoom link upon request.
### Come to PMMH:
www.pmmh.espci.fr/Contact-357
### Next Seminars
April 17: Nicolas Roméo (James Franck Institute, Chicago)
BREAK
May 22: Vava Gligorov (LPNHE, Paris)
May 29: Jonathan Fouchard (IBPS, Paris)
June 5: Carlos Málaga Iguiñiz (UNAM, Mexique)
Full list at www.pmmh.espci.fr/Seminaires
During the PhD of Lucas Gey, we have reproduced this phenomenon in the lab, allowing us to investigate their formation, their fragmentation and their mechanical properties
How long will it take for an aggregate to form? Is there a maximum size? At IRPHE, we have started to investigate these questions to understand the formation of natural aggregates called aegagropilae made from Posidonia fibers which are easily found on the Mediterranean shores.
Fiber aggregates are commonly encountered in environmental and industrial flows (paper industry, fiber recycling, etc.). However, the physical mechanisms leading to their formation are still misunderstood. Hence, there is still no clear answer to simple questions such as :
The PMMH seminar on Friday 10 April at 11:00 will host Gauthier Verhille from IRPhE (Marseille).
Title: Formation and fragmentation of fiber aggregates in turbulent flows
Abstract below. Zoom link upon request.
Directions to PMMH:
www.pmmh.espci.fr/Contact-357
Next Seminars:
April 10:Gautier Verhille (IRPHE, Marseille)
April 17: Nicolas Roméo (James Franck Institute, Chicago)
BREAK
May 22: Vava Gligorov (LPNHE, Paris)
May 29: Jonathan Fouchard (IBPS, Paris)
Full list at www.pmmh.espci.fr/Seminaires
Finally, I will describe an ongoing work on the acoustic response of antibubbles under excitation. Two resonances are measured with a 4 ms time resolution: I will discuss these results and our current efforts to understand them.
This technique showed that the thickness evolution in time is strongly affected by mass exchanges with the surrounding bulk ie by gas dissolution/desorption. An “antibubble column” was then designed to measure these fluxes and how the nature of surfactants used may affect them.
I present recent experiments conducted on antibubbles made in surfactants-containing aqueous solutions. We produce these unusual objects by hand. I will show that their spherical geometry allows for the determination of the thickness profile using only a monochromatic source of light and a camera.
Because of the higher hydrostatic pressure at the bottom, the gas film undergoes a gravitationally-driven drainage from the bottom to the top, that eventually leads to the film rupture and antibubble collapse.
An antibubble is a spherical thin film of gas, that encapsulates a droplet, within a liquid medium. The typical size of an antibubble is one centimeter while the thickness of the gas film is of micrometric order.
The PMMH seminar on Friday 3 April at 11:00 will host
Jonas Miguet, from MSC (Univ. Paris Cité).
Antibubbles: optical interferometry, gas transfers and acoustic signature
Abstract below. Zoom link upon request.
Directions to PMMH:
www.pmmh.espci.fr/Contact-357
Next Seminars
April 3rd: Jonas Miguet (MSC, Paris)
April 10th:Gautier Verhille (IRPHE, Marseille)
April 17th: Nicolas Roméo (James Franck Institute, Chicago)
Break
May 22nd: Vava Gligorov (LPNHE, Paris)
Full list at www.pmmh.espci.fr/Seminaires
Results will be extended to more realistic 3D simulations, which serve as the foundation for an experimental microgravity project (supported by CNES) aimed at validating these predictions.
This seminar will present a theoretical analysis of bifurcations in a 1D model, highlighting the critical role of parity symmetry and geometry, as well as the influence of small fluctuations on transport.
The ratchet effect enables directed transport of particles in noisy systems, even in the absence of a net force (zero bias). When exploited in periodic structures, this phenomenon paves the way for innovative applications in selective microparticle sorting.
On Friday 27 March at 11am, the PMMH seminar hosts Philippe Beltrame from Avignon Université.
Ratchet Effect for Selective Transport of Microparticles in Fluid Suspension
Abstract below. Zoom link upon request.
## Directions to PMMH:
www.pmmh.espci.fr/Contact-357
## Next Seminars
27 Mars : Philippe Beltrame (U. Avignon)
3 Avril : Jonas Miguet (MSC, Paris)
10 Avril : Gautier Verhille (IRPHE, Marseille)
17 Avril : Nicolas Roméo (James Franck Institute, Chicago)
Full list at www.pmmh.espci.fr/Seminaires
subject to a vertical through-flow induced by evaporation and to buoyancy forces: the salt crust yields an unstable stratification and competes with the evaporative drive. I describe how this instability develops and how it ultimately leads to the emergence of polygonal structures at the surface.
Understanding the formation of these patterns is a fascinating problem in itself, but it is also important for controlling dust emission. I will describe the main physical processes driving the fluid dynamics beneath the surface of these lakes. The system is modeled as a 3D porous medium
In such environments, evaporation plays an important role, driving dissolved minerals upward and leading to the growth of a salt crust, known to form polygonal patterns with characteristic wavelength of ~1m, bounded by ridges ~10cm tall. These patterns show remarkably little variability on Earth.
Dry salt lakes form spectacular landscapes in arid regions. Strong evaporation and weak precipitation (but also human intervention) can progressively deplete lakes of water, leaving surfaces that appear dry while the water table remains shallow.
On Friday 20 March at 11am, the PMMH seminar hosts Cédric Beaume from the University of Leeds.
Title: A fluid instability at the origin of salt polygons
Abstract below. Zoom link upon request.