Kinesin and Myosin Motors Compete to Drive Rich Multi-Phase Dynamics in Programmable Cytoskeletal Composites

Abstract The cytoskeleton of biological cells relies on a diverse population of motors, filaments, and binding proteins acting in concert to enable non-equilibrium processes ranging from mitosis to chemotaxis. The cytoskeleton’s versatile reconfigurability, programmed by interactions between its constituents, make it a foundational active matter platform. However, current active matter endeavors are limited largely to single force-generating components acting on a single substrate – far from the composite cytoskeleton in live cells. Here, we engineer actin-microtubule composites, driven by kinesin and myosin motors and tuned by crosslinkers, that restructure into diverse morphologies from interpenetrating filamentous networks to de-mixed amorphous clusters. Our Fourier analyses reveal that kinesin and myosin compete to delay kinesin-driven restructuring and suppress de-mixing and flow, while crosslinking accelerates reorganization and promotes actin-microtubule correlations. The phase space of non-equilibrium dynamics falls into three broad classes– slow reconfiguration, fast advective flow, and multi-mode ballistic dynamics – with structure-dynamics relations described by the relative contributions of elastic and dissipative responses to motor-generated forces.

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Temperature chaos is present in off-equilibrium spin-glass dynamics

Communications Physics ◽

10.1038/s42005-021-00565-9 ◽

2021 ◽

Vol 4 (1) ◽

Author(s):

Marco Baity-Jesi ◽

Enrico Calore ◽

Andrés Cruz ◽

Luis Antonio Fernandez ◽

José Miguel Gil-Narvion ◽

...

Keyword(s):

Spin Glass ◽

Dynamic Effect ◽

Large Degree ◽

Equilibrium Temperature ◽

Experimental Conditions ◽

Temperature Changes ◽

Equilibrium Dynamics ◽

Glass Dynamics ◽

Extreme Sensitivity ◽

Non Equilibrium

AbstractExperiments featuring non-equilibrium glassy dynamics under temperature changes still await interpretation. There is a widespread feeling that temperature chaos (an extreme sensitivity of the glass to temperature changes) should play a major role but, up to now, this phenomenon has been investigated solely under equilibrium conditions. In fact, the very existence of a chaotic effect in the non-equilibrium dynamics is yet to be established. In this article, we tackle this problem through a large simulation of the 3D Edwards-Anderson model, carried out on the Janus II supercomputer. We find a dynamic effect that closely parallels equilibrium temperature chaos. This dynamic temperature-chaos effect is spatially heterogeneous to a large degree and turns out to be controlled by the spin-glass coherence length ξ. Indeed, an emerging length-scale ξ* rules the crossover from weak (at ξ ≪ ξ*) to strong chaos (ξ ≫ ξ*). Extrapolations of ξ* to relevant experimental conditions are provided.

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Epidemic growth and Griffiths effects on an emergent network of excited atoms

Nature Communications ◽

10.1038/s41467-020-20333-7 ◽

2021 ◽

Vol 12 (1) ◽

Author(s):

T. M. Wintermantel ◽

M. Buchhold ◽

S. Shevate ◽

M. Morgado ◽

Y. Wang ◽

...

Keyword(s):

Complex Systems ◽

Power Laws ◽

Excitation Density ◽

Griffiths Phase ◽

Many Body ◽

Excited Atoms ◽

Equilibrium Dynamics ◽

Many Body Systems ◽

Excitation Number ◽

Non Equilibrium

AbstractWhether it be physical, biological or social processes, complex systems exhibit dynamics that are exceedingly difficult to understand or predict from underlying principles. Here we report a striking correspondence between the excitation dynamics of a laser driven gas of Rydberg atoms and the spreading of diseases, which in turn opens up a controllable platform for studying non-equilibrium dynamics on complex networks. The competition between facilitated excitation and spontaneous decay results in sub-exponential growth of the excitation number, which is empirically observed in real epidemics. Based on this we develop a quantitative microscopic susceptible-infected-susceptible model which links the growth and final excitation density to the dynamics of an emergent heterogeneous network and rare active region effects associated to an extended Griffiths phase. This provides physical insights into the nature of non-equilibrium criticality in driven many-body systems and the mechanisms leading to non-universal power-laws in the dynamics of complex systems.

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