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Microtubules are filamentous tubular protein polymers which are essential for a range of cellular behaviour, and are generally straight over micron length scales. However, in some gliding assays, where microtubules move over a carpet of…

Subcellular Processes · Quantitative Biology 2018-08-02 Simon P Pearce , Matthias Heil , Oliver E Jensen , Gareth W Jones , Andreas Prokop

The cytoskeleton relies on diverse populations of motors, filaments, and binding proteins acting in concert to enable non-equilibrium processes ranging from mitosis to chemotaxis. Its versatile reconfigurability, programmed by interactions…

In vitro reconstituted active systems, such as the ATP-driven microtubule bundle suspension developed by the Dogic group, provide a fertile testing ground for elucidating the phenomenology of active liquid crystalline states. Controlling…

Soft Condensed Matter · Physics 2017-01-04 Pau Guillamat , Jordi Ignés-Mullol , Suraj Shankar , M. Cristina Marchetti , Francesc Sagués

We study, via extensive numerical simulations, the force-velocity curve of an active particle advected by a steady laminar flow, in the nonlinear response regime. Our model for an active particle relies on a colored noise term that mimics…

Statistical Mechanics · Physics 2018-06-07 F. Cecconi , A. Puglisi , A. Sarracino , A. Vulpiani

Oscillatory flow in confined spaces is central to understanding physiological flows and rational design of synthetic periodic-actuation based micromachines. Using theory and experiments on oscillating flows generated through a laser-induced…

Active matter comprises individual units that convert energy into mechanical motion. In many examples, such as bacterial systems and biofilament assays, constituent units are elongated and can give rise to local nematic orientational order.…

Soft Condensed Matter · Physics 2020-11-17 He Li , Xia-qing Shi , Mingji Huang , Xiao Chen , Mingfeng Xiao , Chenli Liu , Hugues Chate , H. P. Zhang

We introduce a two-dimensional active nematic with quenched disorder. We write the coarse-grained hydrodynamic equations of motion for slow variables, viz. density, and orientation. Disorder strength is tuned from zero to large values.…

Soft Condensed Matter · Physics 2021-07-15 Sameer Kumar , Shradha Mishra

We present simulations of the dynamic critical state for a 2D superconductor with strong pinning centers, corresponding to a matching field twice the applied magnetic field. The sharp crossover between the plastic regime, at low current…

Superconductivity · Physics 2009-10-31 D. Monier , L. Fruchter

Cell crawling on flat substrates is based on intracellular flows of the actin cytoskeleton that are driven by both actin polymerization at the front and myosin contractility at the back. The new experimental tool of optogenetics makes it…

Subcellular Processes · Quantitative Biology 2023-07-04 Oliver M. Drozdowski , Falko Ziebert , Ulrich S. Schwarz

We use a continuum, two-fluid approach to study a mixture of two active nematic fluids. Even in the absence of thermodynamically-driven ordering, for mixtures of different activities we observe turbulent microphase separation, where domains…

Soft Condensed Matter · Physics 2025-02-03 Saraswat Bhattacharyya , Julia M. Yeomans

We present polarization-independent optical shutters with a sub-millisecond switching time. The approach utilizes dual-frequency nematics doped with a dichroic dye. Two nematic cells with orthogonal alignment are driven simultaneously by a…

Atomic layer crystals are emerging building blocks for enabling new two-dimensional (2D) nanomechanical systems, whose motions can be coupled to other attractive physical properties in such 2D systems. Optical interferometry has been very…

Mesoscale and Nanoscale Physics · Physics 2016-09-27 Zenghui Wang , Philip X. -L. Feng

We consider a phenomenological continuum theory for an extensile, overdamped active nematic liquid crystal, applicable in the dense regime. Constructed from general principles, the theory is universal, with parameters independent of any…

Soft Condensed Matter · Physics 2015-06-12 Elias Putzig , Gabriel S. Redner , Arvind Baskaran , Aparna Baskaran

We examine the dynamics of a compressible active nematic liquid crystal on a frictional substrate. When frictional damping dominates over viscous dissipation, we eliminate flow in favor of active stresses to obtain a minimal dynamical model…

Soft Condensed Matter · Physics 2016-11-07 Pragya Srivastava , Prashant Mishra , M. Cristina Marchetti

This paper presents a novel architecture for simultaneous estimation of highly accurate optical flows and rigid scene transformations for difficult scenarios where the brightness assumption is violated by strong shading changes. In the case…

Computer Vision and Pattern Recognition · Computer Science 2022-09-15 Torben Fetzer , Gerd Reis , Didier Stricker

In living cells, motor proteins, such as kinesin and dynein can move processively along microtubule (MT), and also detach from or attach to MT stochastically. Experiments have found that, the traffic of motor might be jammed, and various…

Biological Physics · Physics 2015-03-06 Yunxin Zhang

Active gels are a class of biologically-relevant material containing embedded agents that spontaneously generate forces acting on a sparse filament network. In vitro experiments of protein filaments and molecular motors have revealed a…

Soft Condensed Matter · Physics 2024-06-03 David A. Head , Gerhard Gompper , W. J. Briels

We consider a continuum model of active viscoelastic matter, whereby an active nematic liquid-crystal is coupled to a minimal model of polymer dynamics with a viscoelastic relaxation time $\tau_C$. To explore the resulting interplay between…

Soft Condensed Matter · Physics 2016-03-30 E. J. Hemingway , M. E. Cates , S. M. Fielding

Microfluidics involves the manipulation of flows at the microscale, typically requiring external power sources to generate pressure gradients. Alternatively, harnessing flows from active fluids, which are usually chaotic, has been proposed…

In this work we present the first systematic framework to sculpt active nematics systems, using optimal control theory and a hydrodynamic model of active nematics. We demonstrate the use of two different control fields, (1) applied…

Soft Condensed Matter · Physics 2020-10-28 Michael M. Norton , Piyush Grover , Michael F. Hagan , Seth Fraden