laboratoire de physique statistique
 
 
laboratoire de physique statistique

Publications

Rechercher
2016 


Martine BEN AMAR 


4
P U B L I C A T I O N S

S E L E C T I O N N E R
P A R M I :



 
2016
Collective chemotaxis and segregation of active bacterial colonies - Ben Amar, M.
SCIENTIFIC REPORTS 6 (2016) 
LPS


Abstract : Still recently, bacterial fluid suspensions have motivated a lot of works, both experimental and theoretical, with the objective to understand their collective dynamics from universal and simple rules. Since some species are active, most of these works concern the strong interactions that these bacteria exert on a forced flow leading to instabilities, chaos and turbulence. Here, we investigate the self-organization of expanding bacterial colonies under chemotaxis, proliferation and eventually active-reaction. We propose a simple model to understand and quantify the physical properties of these living organisms which either give cohesion or on the contrary dispersion to the colony. Taking into account the diffusion and capture of morphogens complicates the model since it induces a bacterial density gradient coupled to bacterial density fluctuations and dynamics. Nevertheless under some specific conditions, it is possible to investigate the pattern formation as a usual viscous fingering instability. This explains the similarity and differences of patterns according to the physical bacterial suspension properties and explain the factors which favor compactness or branching.
Multiscale modeling of fibrosis - What's next? Reply to Comments on ``Towards a unified approach in the modeling of fibrosis: A review with research perspective'' by Martine Ben Amar and Carlo Bianca - Ben Amar, Martine and Bianca, Carlo
PHYSICS OF LIFE REVIEWS 17118-123 (2016) 
LPS
Towards a unified approach in the modeling of fibrosis: A review with research perspectives - Ben Amar, Martine and Bianca, Carlo
PHYSICS OF LIFE REVIEWS 1761-85 (2016) 
LPS


Abstract : Pathological fibrosis is the result of a failure in the wound healing process. The comprehension and the related modeling of the different mechanisms that trigger fibrosis are a challenge of many researchers that work in the field of medicine and biology. The modern scientific analysis of a phenomenon generally consists of three major approaches: theoretical, experimental, and computational. Different theoretical tools coming from mathematics and physics have been proposed for the modeling of the physiological and pathological fibrosis. However a complete framework is missing and the development of a general theory is required. This review aims at finding a unified approach in the modeling of fibrosis diseases that takes into account the different phenomena occurring at each level: molecular, cellular and tissue. Specifically by means of a critical analysis of the different models that have been proposed in the mathematical, computational and physical biology, from molecular to tissue scales, a multiscale approach is proposed, an approach that has been strongly recommended by top level biologists in the past decades. (C) 2016 Elsevier B.V. All rights reserved.
Onset of nonlinearity in a stochastic model for auto-chemotactic advancing epithelia - Ben Amar, Martine and Bianca, Carlo
SCIENTIFIC REPORTS 6 (2016) 
LPS


Abstract : We investigate the role of auto-chemotaxis in the growth and motility of an epithelium advancing on a solid substrate. In this process, cells create their own chemoattractant allowing communications among neighbours, thus leading to a signaling pathway. As known, chemotaxis provokes the onset of cellular density gradients and spatial inhomogeneities mostly at the front, a phenomenon able to predict some features revealed in in vitro experiments. A continuous model is proposed where the coupling between the cellular proliferation, the friction on the substrate and chemotaxis is investigated. According to our results, the friction and proliferation stabilize the front whereas auto-chemotaxis is a factor of destabilization. This antagonist role induces a fingering pattern with a selected wavenumber k(0). However, in the planar front case, the translational invariance of the experimental set-up gives also a mode at k = 0 and the coupling between these two modes in the nonlinear regime is responsible for the onset of a Hopf-bifurcation. The time-dependent oscillations of patterns observed experimentally can be predicted simply in this continuous non-linear approach. Finally the effects of noise are also investigated below the instability threshold.