Ref HAL: hal-01939701_v1
DOI: 10.1051/epjconf/20134403001
WoS: 000326984100007
Exporter : BibTex | endNote
Résumé:

We give a short overview of the results for large deviations of dynamical quantities obtained formodels of glassy systems. We introduce the paper with the study of kinetically constrained models (KCMs), first without external forcing. In these models, it has been shown using the thermodynamic formalism for histories, that there is a coexistence between an active and an inactive phase. Later, it has been found that adding a driving field to a KCM model leads to a singularity in the large deviation function of the currentat large fields. Finally we report on recent studies on realistic glassy systems, and open directions for future research

Ref HAL: hal-00816492_v1
PMID 23410357
DOI: 10.1103/PhysRevE.87.012705
WoS: 000314150800002
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24 Citations
Résumé:

Many transport processes in nature take place on substrates, often considered as unidimensional lanes. These unidimensional substrates are typically nonstatic: Affected by a fluctuating environment, they can undergo conformational changes. This is particularly true in biological cells, where the state of the substrate is often coupled to the active motion of macromolecular complexes, such as motor proteins on microtubules or ribosomes on mRNAs, causing new interesting phenomena. Inspired by biological processes such as protein synthesis by ribosomes and motor protein transport, we introduce the concept of localized dynamical sites coupled to a driven lattice gas dynamics. We investigate the phenomenology of transport in the presence of dynamical defects and find a regime characterized by an intermittent current and subject to severe finite-size effects. Our results demonstrate the impact of the regulatory role of the dynamical defects in transport not only in biology but also in more general contexts. DOI: 10.1103/PhysRevE.87.012705

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(à compléter)

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(en cours)

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(en cours)

Ref HAL: hal-00364938_v1
Ref Arxiv: 0810.5298
DOI: 10.1088/1751-8113/42/7/075007
WoS: 000262583100010
Ref. & Cit.: NASA ADS
Exporter : BibTex | endNote
247 Citations
Résumé:

We investigate the dynamics of kinetically constrained models of glassformers by analysing the statistics of trajectories of the dynamics, orhistories, using large deviation function methods. We show that, in general,these models exhibit a first-order dynamical transition between active andinactive dynamical phases. We argue that the dynamical heterogeneitiesdisplayed by these systems are a manifestation of dynamical first-order phasecoexistence. In particular, we calculate dynamical large deviation functions,both analytically and numerically, for the Fredrickson-Andersen model, the Eastmodel, and constrained lattice gas models. We also show how large deviationfunctions can be obtained from a Landau-like theory for dynamical fluctuations.We discuss possibilities for similar dynamical phase-coexistence behaviour inother systems with heterogeneous dynamics.

Commentaires: 29 pages, 7 figs,

Ref HAL: hal-00364561_v1
Ref Arxiv: 0812.3559
Ref. & Cit.: NASA ADS
Exporter : BibTex | endNote
Résumé:

Using molecular dynamics computer simulations we investigate the agingdynamics of a gel. We start from a fractal structure generated by the DLCA-DEFalgorithm, onto which we then impose an interaction potential consisting of ashort-range attraction as well as a long-range repulsion. After relaxing thesystem at T=0, we let it evolve at a fixed finite temperature. Depending on thetemperature T we find different scenarios for the aging behavior. For T>0.2 thefractal structure is unstable and breaks up into small clusters which relax toequilibrium. For T<0.2 the structure is stable and the dynamics slows down withincreasing waiting time. At intermediate and low T the mean squareddisplacement scales as t^{2/3} and we discuss several mechanisms for thisanomalous time dependence. For intermediate T, the self-intermediate scatteringfunction is given by a compressed exponential at small wave-vectors and by astretched exponential at large wave-vectors. In contrast, for low T it is astretched exponential for all wave-vectors. This behavior can be traced back toa subtle interplay between elastic rearrangements, fluctuations of chain-likefilaments, and heterogeneity.

Commentaires: 30 pages, 25 figures