Profiling the overdamped dynamics of a nonadiabatic system

Sarkar, Piyush Kanti; Shit, Anindita; Chattopadhyay, Sudip; Banik, Suman Kumar

doi:10.1016/j.chemphys.2015.07.010

Cited by 4 publications

(4 citation statements)

References 59 publications

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“…The associated pseudo-energy wells with resonant nature may be crucially involved in securing robustness of the near critical behavior of the muscle system. Needless to say that the mastery of tunable rigidity in artificial conditions can open interesting prospects not only in biomechanics [370] but also in engineering design incorporating negative stiffness [371] or aiming at synthetic materials involving dynamic stabilization [372,373].…”

Section: Discussionmentioning

confidence: 99%

Physics of muscle contraction

Caruel

Truskinovsky

2018

Rep. Prog. Phys.

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In this paper we report, clarify and broaden various recent efforts to complement the chemistry-centered models of force generation in (skeletal) muscles by mechanics-centered models. The physical mechanisms of interest can be grouped into two classes: passive and active. The main passive effect is the fast force recovery which does not require the detachment of myosin cross-bridges from actin filaments and can operate without a specialized supply of metabolic fuel (ATP). In mechanical terms, it can be viewed as a collective folding-unfolding phenomenon in the system of interacting bi-stable units and modeled by near equilibrium Langevin dynamics. The active force generation mechanism operates at slow time scales, requires detachment and is crucially dependent on ATP hydrolysis. The underlying mechanical processes take place far from equilibrium and are represented by stochastic models with broken time reversal symmetry implying non-potentiality, correlated noise or multiple reservoirs. The modeling approaches reviewed in this paper deal with both active and passive processes and support from the mechanical perspective the biological point of view that phenomena involved in slow (active) and fast (passive) force generation are tightly intertwined. They reveal, however, that biochemical studies in solution, macroscopic physiological measurements and structural analysis do not provide by themselves all the necessary insights into the functioning of the organized contractile system. In particular, the reviewed body of work emphasizes the important role of long-range interactions and criticality in securing the targeted mechanical response in the physiological regime of isometric contractions. The importance of the purely mechanical micro-scale modeling is accentuated at the end of the paper where we address the puzzling issue of the stability of muscle response on the so called 'descending limb' of the isometric tetanus.

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Section: Discussionmentioning

confidence: 99%

Physics of muscle contraction

Caruel

Truskinovsky

2018

Rep. Prog. Phys.

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mentioning

confidence: 99%

“…The proposed mechanism of rigidity generation requires a finite distance from equilibrium and is therefore different from the more conventional entropic stabilization [18]. The possibility of actively tunable rigidity opens interesting prospects not only in biomechanics [19] but also in engineering design incorporating negative stiffness [20] or aiming at synthetic materials stabilized dynamically [21,22].We illustrate our idea on a simple bi-stable mechanical system described by a single collective variable: the negative stiffness is viewed as a result of coarse-graining in a microscopic system with domineering long range interactions [23]. We assume that this 'snap-spring' is exposed to both thermal and correlated noises and acts against a linear spring which qualifies it as a molecular motor operating in stall conditions [24].…”

mentioning

confidence: 99%

Rigidity generation by nonthermal fluctuations

2016

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Active stabilization in systems with zero or negative stiffness is an essential element of a wide variety of biological processes. We study a prototypical example of this phenomenon at a microscale and show how active rigidity, interpreted as a formation of a pseudo-well in the effective energy landscape, can be generated in an overdamped ratchet-type stochastic system. We link the transition from negative to positive rigidity with correlations in the noise and show that subtle differences in out-of-equilibrium driving may compromise the emergence of a pseudo-well. The response of a living system to mechanical loading depends not only on the properties of the constituents and their connectivity, but also on the presence of nonthermal endogenous driving [1]. Thus, molecular motors can either stiffen the cytoskeleton through actively generated pre-stress [2] or fluidize it by facilitating remodeling [3]. Powered by ATP hydrolysis, living systems can also operate in mechanical regimes with negative passive stiffness as in the case of hair cells [4,5] and muscle halfsarcomeres [6,7]. In those cases metabolic resources are used to modify the mechanical susceptibility of the system and stabilize the apparently unstable states [8][9][10].At the structural level, active rigidity may be the outcome of tensegrity tightening [11], connectivity change [12], steric interactions [13], or the prestress exploiting strong nonlinearity of the passive response [14,15]. ATP induced stiffening can even take place at the level of individual structural elements as in the case of the Frank-Starling effect in cardiac muscles that cannot be explained by a simple filament overlap change [16].In this Letter we show that active rigidity can also emerge at the micro-scale level through resonant nonthermal excitation of molecular degrees of freedom as in the case of an inverted pendulum [17]. Following this inertial prototype, we construct an example of a mechanically unstable overdamped system where stabilization and creation of a new pseudo-well in the effective energy landscape can be induced by a colored noise. The proposed mechanism of rigidity generation requires a finite distance from equilibrium and is therefore different from the more conventional entropic stabilization [18]. The possibility of actively tunable rigidity opens interesting prospects not only in biomechanics [19] but also in engineering design incorporating negative stiffness [20] or aiming at synthetic materials stabilized dynamically [21,22].We illustrate our idea on a simple bi-stable mechanical system described by a single collective variable: the negative stiffness is viewed as a result of coarse-graining in a microscopic system with domineering long range interactions [23]. We assume that this 'snap-spring' is exposed to both thermal and correlated noises and acts against a linear spring which qualifies it as a molecular motor operating in stall conditions [24]. Instead of the conventional focus on active force, we study in this Letter a possibility of generating ...

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“…The proposed mechanism of rigidity generation requires a finite distance from equilibrium and is therefore different from the more conventional entropic stabilization [18]. The possibility of actively tunable rigidity opens interesting prospects not only in biomechanics [19] but also in engineering design incorporating negative stiffness [20] or aiming at synthetic materials stabilized dynamically [21,22]. We illustrate our idea on a simple bi-stable mechanical system described by a single collective variable: the negative stiffness is viewed as a result of coarse-graining in a microscopic system with domineering long range interactions [23].…”

mentioning

confidence: 99%

Pseudo energy wells in active systems

Sheshka,

Recho,

Truskinovsky

2015

Preprint

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Profiling the overdamped dynamics of a nonadiabatic system

Cited by 4 publications

References 59 publications

Physics of muscle contraction

Physics of muscle contraction

Rigidity generation by nonthermal fluctuations

Pseudo energy wells in active systems

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