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Publications (en anglais)

  1. Articles scientifiques
  2. Livres
  3. Mémoires

 

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1. Articles scientifiques

  •  

    Flexoelectric fluid membrane vesicles in spherical confinement

    Niloufar Abtahi, Lila Bouzar, Nadia Saidi-Amroun, Martin Michael Müller

    Résumé     Plus d'infos

    EPL, 131(1): 18001, 2020. Cf. aussi arXiv:2006.04475.

     


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    Isometric bending requires local constraints on free edges

    Jemal Guven, Martin Michael Müller, Pablo Vázquez-Montejo

    While the shape equations describing the equilibrium of an unstretchable thin sheet that is free to bend are known, the boundary conditions that supplement these equations on free edges have remained elusive. Intuitively, unstretchability is captured by a constraint on the metric within the bulk. Naïvely one would then guess that this constraint is enough to ensure that the deformations determining the boundary conditions on these edges respect the isometry constraint. If matters were this simple, unfortunately, it would imply unbalanced torques (as well as forces) along the edge unless manifestly unphysical constraints are met by the boundary geometry. In this article, we identify the source of the problem: not only the local arc-length but also the geodesic curvature need to be constrained explicitly on all free edges. We derive the boundary conditions which follow. In contrast to conventional wisdom, there is no need to introduce boundary layers. This framework is applied to isolated conical defects, both with deficit as well, but more briefly, as surplus angles. Using these boundary conditions, we show that the lateral tension within a circular cone of fixed radius is equal but opposite to the radial compression, and independent of the deficit angle itself. We proceed to examine the effect of an oblique outer edge on this cone perturbatively demonstrating that both the correction to the geometry as well as the stress distribution in the cone kicks in at second order in the eccentricity of the edge.

     Fermer     Plus d'infos

    Math. Mech. Solids, 24: 4051, 2019. Cf. aussi arXiv:1904.05855.

     


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    Helical Superstructure of Intermediate Filaments

    Lila Bouzar, Martin Michael Müller, René Messina, Bernd Nöding, Sarah Köster, Hervé Mohrbach, Igor M. Kulić

    Intermediate filaments are the least explored among the large cytoskeletal elements. We show here that they display conformational anomalies in narrow microfluidic channels. Their unusual behavior can be understood as the consequence of a previously undetected, large scale helically curved superstructure. Confinement in a channel orders the otherwise soft, strongly fluctuating helical filaments and enhances their structural correlations, giving rise to experimentally detectable, strongly oscillating tangent correlation functions. We propose an explanation for the detected intrinsic curving phenomenon - an elastic shape instability that we call autocoiling. The mechanism involves self-induced filament buckling via a surface stress located at the outside of the cross-section. The results agree with ultrastructural findings and rationalize for the commonly observed looped intermediate filament shapes. Beyond curvature, explaining the molecular origin of the detected helical torsion remains an interesting challenge.

     Fermer     Plus d'infos

    Phys. Rev. Lett., 122: 098101, 2019. Cf. aussi arXiv:1803.04691.

     


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    Vesicle dynamics in confined steady and harmonically modulated Poiseuille flows

    Zakaria Boujja, Chaouqi Misbah, Hamid Ez-Zahraouy, Abdelilah Benyoussef, Thomas John, Christian Wagner, Martin Michael Müller

    We present a numerical study of the time-dependent motion of a membrane vesicle in a channel under an imposed flow. In a Poiseuille flow the shape of the vesicle depends on the flow strength, the mechanical properties of the membrane, and the width of the channel. In a wide parameter region, the emerging snaking shape shows an oscillatory motion like a swimmer flagella even though the flow is stationary. We quantify this behavior by the amplitude and frequency of the oscillations of the vesicle's center of mass. The influence of an amplitude modulation of the imposed flow on the dynamics and shape of the snaking vesicle is also investigated. We find that this modulation---when sufficiently small---induces a modulation in amplitude and frequency of the center of mass of the snaking vesicle. For large modulation amplitudes transitions to static shapes are observed.

     Fermer     

    Phys. Rev. E, 98: 043111, 2018. Cf. aussi arXiv:1810.04500.

     


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    Confining a fluid membrane vesicle of toroidal topology in an adhesive hard sphere

    Lila Bouzar, Ferhat Menas, Martin Michael Müller

    Résumé     Plus d'infos

    IOP Conf. Series: MSE, 186: 012021, 2017.

     


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    Squeezed helical elastica

    Lila Bouzar, Martin Michael Müller, Pierre Gosselin, Igor M. Kulić, Hervé Mohrbach

    Résumé     Plus d'infos

    Eur. Phys. J. E, 39: 114, 2016. Cf. aussi arXiv:1606.03611.

     


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    How bio-filaments twist membranes

    Julien Fierling, Albert Johner, Igor M. Kulić, Hervé Mohrbach, Martin Michael Müller

    Résumé     

    Soft Matter, 12: 5747, 2016.

     


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    Toroidal membrane vesicles in spherical confinement

    Lila Bouzar, Ferhat Menas, Martin Michael Müller

    Résumé     Plus d'infos

    Phys. Rev. E, 92: 032721, 2015. Cf. aussi arXiv:1509.00765.

     


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    Non-linear buckling and symmetry breaking of a soft elastic sheet sliding on a cylindrical substrate

    Norbert Stoop, Martin Michael Müller

    Résumé     Plus d'infos

    Int. J. Non-Linear Mech., 75: 115, 2015. Cf. aussi arXiv:1503.05030.

     


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    Crunching Biofilament Rings

    Julien Fierling, Martin Michael Müller, Hervé Mohrbach, Albert Johner, Igor M. Kulić

    We discuss a curious example for the collective mechanical behavior of coupled non-linear monomer units entrapped in a circular filament. Within a simple model we elucidate how multistability of monomer units and exponentially large degeneracy of the filament's ground state emerge as a collective feature of the closed filament. Surprisingly, increasing the monomer frustration, i.e., the bending prestrain within the circular filament, leads to a conformational softening of the system. The phenomenon, that we term polymorphic crunching, is discussed and applied to a possible scenario for membrane tube deformation by switchable dynamin or FtsZ filaments. We find an important role of cooperative inter-unit interaction for efficient ring induced membrane fission.

     Fermer     Plus d'infos

    Europhys. Lett., 107(6): 68002, 2014. Cf. aussi arXiv:1408.6787.

     


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    Confotronic dynamics of tubular filaments

    Osman Kahraman, Hervé Mohrbach, Martin Michael Müller, Igor M. Kulić

    Résumé     Plus d'infos

    Soft Matter, 10(16): pp. 2836-2847, 2014. Cf. aussi arXiv:1312.3106.

     


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    Whirling skirts and rotating cones

    Jemal Guven, J. A. Hanna, Martin Michael Müller

    Résumé     

    New J. Phys., 15: 113055, 2013. Cf. aussi arXiv:1306.2619.

     


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    Myotubularin and PtdIns3P remodel the sarcoplasmic reticulum in muscle in vivo

    Leonela Amoasii, Karim Hnia, Gaëtan Chicanne, Andreas Brech, Belinda Simone Cowling, Martin Michael Müller, Yannick Schwab, Pascale Koebel, Arnaud Ferry, Bernard Payrastre, Jocelyn Laporte

    Résumé     

    J. Cell Sci., 126(8): 1806, 2013.

     


  •  

    Dipoles in thin sheets

    Jemal Guven, J. A. Hanna, Osman Kahraman, Martin Michael Müller

    A flat elastic sheet may contain pointlike conical singularities that carry a metrical "charge" of Gaussian curvature. Adding such elementary defects to a sheet allows one to make many shapes, in a manner broadly analogous to the familiar multipole construction in electrostatics. However, here the underlying field theory is non-linear, and superposition of intrinsic defects is non-trivial as it must respect the immersion of the resulting surface in three dimensions. We consider a "charge-neutral" dipole composed of two conical singularities of opposite sign. Unlike the relatively simple electrostatic case, here there are two distinct stable minima and an infinity of unstable equilibria. We determine the shapes of the minima and evaluate their energies in the thin-sheet regime where bending dominates over stretching. Our predictions are in surprisingly good agreement with experiments on paper sheets.

     Fermer     Plus d'infos

    Eur. Phys. J. E, 36: 106, 2013. Cf. aussi arXiv:1212.3262.

     


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    Fluid membrane vesicles in confinement

    Osman Kahraman, Norbert Stoop, Martin Michael Müller

    We numerically study the morphology of fluid membrane vesicles with prescribed volume and surface area in confinement. For spherical confinement we observe axisymmetric invaginations that transform into ellipsoidal invaginations a the area of the vesicle is increased, followed by a transition into stomatocyte-like shapes. We provide a detailed analysis of the axisymmetric shapes and investigate the effect of the spontaneous curvature of the membrane as a possible mechanism for shape regulation. We show that the observed morphologies are stable under small geometric deformations of the confinement. The results could help to understand the role of mechanics in the complex folding patterns of biological membranes.

     Fermer     Plus d'infos

    New J. Phys., 14: 095021, 2012.

     


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    Petal shapes of sympetaleous flowers: the interplay between growth, geometry and elasticity

    Martine Ben Amar, Martin Michael Müller, Miguel Trejo

    Résumé     Plus d'infos

    New J. Phys., 14: 085014, 2012. Choisi pour les Highlights of 2012.

     


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    Morphogenesis of membrane invaginations in spherical confinement

    Osman Kahraman, Norbert Stoop, Martin Michael Müller

    We study the morphology of a fluid membrane in spherical confinement. When the area of the membrane is slightly larger than the area of the outer container, a single axisymmetric invagination is observed. For higher area, self-contact occurs: the invagination breaks symmetry and deforms into an ellipsoid-like shape connected to its outer part via a small slit. For even higher areas, a second invagination forms inside the original invagination. The folding patterns observed could constitute basic building blocks in the morphogenesis of biological tissues and organelles.

     Fermer     Plus d'infos

    Europhys. Lett., 97(6): 68008, 2012. Cf. aussi arXiv:1201.2518.

     


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    Conical instabilities on paper

    Jemal Guven, Martin Michael Müller, Pablo Vázquez-Montejo

    Résumé     Plus d'infos

    J. Phys. A: Math. Theor., 45(1): 015203, 2012. Cf. aussi arXiv:1107.5008.

     


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    Interface-mediated interactions: Entropic forces of curved membranes

    Pierre Gosselin, Hervé Mohrbach, Martin Michael Müller

    Résumé     Plus d'infos

    Phys. Rev. E, 83(5): 051921, 2011. Cf. aussi arXiv:1011.1221.

     


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    Self-Contact and Instabilities in the Anisotropic Growth of Elastic Membranes

    Norbert Stoop, Falk K. Wittel, Martine Ben Amar, Martin Michael Müller, Hans J. Herrmann

    Résumé     Plus d'infos

    Phys. Rev. Lett., 105(6): 068101, 2010. Cf. aussi arXiv:1007.1871.

     


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    Cell Model Approach to Membrane Mediated Protein Interactions

    Martin Michael Müller, Markus Deserno

    Résumé     Plus d'infos

    Prog. Theor. Phys. Suppl., 184: pp. 351-363, 2010.

     


  •  

    Hamiltonian formulation of surfaces with constant Gaussian curvature

    Miguel Trejo, Martine Ben Amar, Martin Michael Müller

    Dirac's method for constrained Hamiltonian systems is used to describe surfaces of constant Gaussian curvature. A geometrical free energy, for which these surfaces are equilibrium states, is introduced and interpreted as an action. An equilibrium surface can then be generated by the evolution of a closed space curve. Since the underlying action depends on second derivatives, the velocity of the curve and its conjugate momentum must be included in the set of phase space variables. Furthermore, the action is linear in the acceleration of the curve and possesses a local symmetry---reparametrization invariance---which implies primary constraints in the canonical formalism. These constraints are incorporated into the Hamiltonian through Lagrange multiplier functions, that are identified as the components of the acceleration of the curve. The formulation leads to four first order partial differential equations, one for each canonical variable. With the appropriate choice of parametrization only one of these equations has to be solved to obtain the surface which is swept out by the evolving space curve. To illustrate the formalism, several evolutions of pseudospherical surfaces are discussed.

     Fermer     Plus d'infos

    J. Phys. A: Math. Theor., 42(42): 425204, 2009.

     


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    Local Membrane Mechanics of Pore-Spanning Bilayers

    Ingo Mey, Milena Stephan, Eva K. Schmitt, Martin Michael Müller, Martine Ben Amar, Claudia Steinem, Andreas Janshoff

    Résumé     Plus d'infos

    J. Am. Chem. Soc., 131(20): pp. 7031-7039, 2009.

     


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    Elasticity Mapping of Pore-Suspending Native Cell Membranes

    Bärbel Lorenz, Ingo Mey, Siegfried Steltenkamp, Tamir Fine, Christina Rommel, Martin Michael Müller, Alexander Maiwald, Joachim Wegener, Claudia Steinem, Andreas Janshoff

    Résumé     Plus d'infos

    Small, 5(7): pp. 832-838, 2009.

     


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    Conical Defects in Growing Sheets

    Martin Michael Müller, Martine Ben Amar, Jemal Guven

    Résumé     Plus d'infos

    Phys. Rev. Lett., 101(15): 156104, 2008. Cf. aussi arXiv:0807.1814.

     


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    How paper folds: bending with local constraints

    Jemal Guven, Martin Michael Müller

    Résumé     Plus d'infos

    J. Phys. A: Math. Theor., 41(5): 055203, 2008. Cf. aussi arXiv:0712.0978.

     


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    Contact lines for fluid surface adhesion

    Markus Deserno, Martin Michael Müller, Jemal Guven

    Résumé     Plus d'infos

    Phys. Rev. E, 76(1): 011605, 2007. Cf. aussi cond-mat/0703019.
    Choisi pour le Virtual Journal of Biological Physics Research.

     


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    Balancing torques in membrane-mediated interactions: Exact results and numerical illustrations

    Martin Michael Müller, Markus Deserno, Jemal Guven

    Résumé     Plus d'infos

    Phys. Rev. E, 76(1): 011921, 2007. Cf. aussi cond-mat/0702340.
    Choisi pour le Virtual Journal of Biological Physics Research.

     


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    Aggregation and vesiculation of membrane proteins by curvature-mediated interactions

    Benedict J. Reynwar, Gregoria Illya, Vagelis A. Harmandaris, Martin Michael Müller, Kurt Kremer, Markus Deserno

    Résumé     Plus d'infos

    Nature 447(7143): pp. 461-464, 2007.

     


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    How to determine local elastic properties of lipid bilayer membranes from atomic-force-microscope measurements: A theoretical analysis

    Davood Norouzi, Martin Michael Müller, Markus Deserno

    Résumé     Plus d'infos

    Phys. Rev. E, 74(6): 061914, 2006. Cf. aussi cond-mat/0602662.
    Choisi pour le Virtual Journal of Biological Physics Research.

     


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    Mechanical Properties of Pore-Spanning Lipid Bilayers Probed by Atomic Force Microscopy

    Siegfried Steltenkamp, Martin Michael Müller, Markus Deserno, Christian Hennesthal, Claudia Steinem, Andreas Janshoff

    Résumé     Plus d'infos

    Biophys. J., 91(1): pp. 217-226, 2006.

     


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    Interface mediated interactions between particles -- a geometrical approach

    Martin Michael Müller, Markus Deserno, Jemal Guven

    Résumé     Plus d'infos

    Phys. Rev. E, 72(6): 061407, 2005. Cf. aussi cond-mat/0506019.
    Choisi pour le Virtual Journal of Biological Physics Research.

     


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    Geometry of surface-mediated interactions

    Martin Michael Müller, Markus Deserno, Jemal Guven

    Résumé     Plus d'infos

    Europhys. Lett., 69(3): pp. 482-488, 2005. Cf. aussi cond-mat/0409043.

     


 

 

2. Livres

 

  • New Trends in the Physics and Mechanics of Biological Systems
    Lecture Notes of the Les Houches Summer School, vol. 92 (Oxford University Press, 2011),
    éd. par Martine Ben Amar, Alain Goriely, Martin Michael Müller et Leticia Cugliandolo.

    Chapitre 9 :
    The physics of the cell membrane
    Martin Michael Müller et Martine Ben Amar.

 

 


 

 

3. Mémoires

  • Theoretical examinations of interface mediated interactions between colloidal particles, mémoire (2004).
  •  

  • Theoretical studies of fluid membrane mechanics, thèse de doctorat (2007).


  • Symmetry breaking in bioelasticity, thèse d'habilitation à diriger des recherches (2015).

 

 

 
     

 

     © Martin Michael Müller