$$B-S$$ B - S transition form-factors with the light-cone QCD sum rules

Wang, Zhi-Gang

doi:10.1140/epjc/s10052-015-3282-3

Cited by 44 publications

(53 citation statements)

References 43 publications

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“…To explore the link between the non-Gaussian behavior and the breakdown of the rotational inverse proportionality between diffusion coefficient and relaxation time shown in Fig. 4, we consider that for small angular displacements the P DF (∆θ) is well approximated by a Gaussian function [56], as we verified by checking the existence of a linear relation between log(P DF (∆θ)/P DF (0)) and ∆θ 2 . A Gaussian fit restricted to the range of ∆θ where this linear relationship holds allows to extract characteristic diffusion coefficients for the slow particles, D R,slow and D R,slow CR , which are also plotted as a function of the relaxation time in Figs.…”

Section: E Heterogeneities and Displacement Distribution Functionsmentioning

confidence: 99%

Dynamics in two-dimensional glassy systems of crowded Penrose kites

Hou

et al. 2019

Phys. Rev. Materials

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We investigate the translational and rotational relaxation dynamics of a crowded two-dimensional system of monodisperse Penrose kites, in which crystallization, quasi-crystallization and nematic ordering are suppressed, from low to high area fractions along the metastable ergodic fluid branch. First, we demonstrate a decoupling between both the translational and the rotational diffusion coefficients and the relaxation time: the diffusivities are not inversely proportional to the relaxation time, neither in the low-density normal liquid regime nor in the high-density supercooled regime. Our simulations reveal that this inverse proportionality breaks in the normal liquid regime due to the Mermin-Wagner long-wavelength fluctuations and in the supercooled regime due to the dynamical heterogeneities. We then show that dynamical heterogeneities are mainly spatial for translational degrees of freedom and temporal for rotational ones, that there is no correlation between the particles with largest translational and rotational displacements, and that different dynamical length scales characterize the translational and the rotational motion. Hence, despite the translational and the rotational glass-transition densities coincide, according to a mode-coupling fit, translations and rotations appear to decorrelate via different dynamical processes.

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Section: E Heterogeneities and Displacement Distribution Functionsmentioning

confidence: 99%

Dynamics in two-dimensional glassy systems of crowded Penrose kites

Hou

et al. 2019

Phys. Rev. Materials

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“…However, in several very surprising cases, diffusion has been observed to be Fickian, that is the MSD remains linear in time, but counter-intuitively G(∆x) is non-Gaussian. This peculiar behavior has been referred to as 'Anomalous, yet Brownian' or 'Fickian yet non-Gaussian' diffusion (FNG), and has been observed in a wide variety of systems ranging from tracer colloids diffusing in suspensions of swimming microorganisms [14], colloidal particles diffusing on phospholipid tubules and entangled actin filaments [10], liposomes diffusing in nematic solutions of F-actin filaments [15], peptide coated gold nanoparticles weakly interacting with peptide coated sur-faces [16], polymer chains diffusing on a surface [17,18], colloidal particles diffusing among swimming cells [19], colloidal spheres in a matrix of larger colloidal spheres [20] and quasi 2D colloidal hard sphere fluids [21]. Several theories have been put forward to explain such behavior which include the diffusing diffusivity model [22][23][24][25] that considers dynamic heterogeneities experienced by each colloidal particle in a changing environment.…”

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confidence: 99%

Disorder-induced Fickian, yet non-Gaussian diffusion in heterogeneous media

Chakraborty

Roichman

2020

Phys. Rev. Research

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Fickian yet non-Gaussian diffusion has been observed in several biological and soft matter systems, but the underlying reasons behind the emergence of non-Gaussianity while simultaneously retaining the linear nature of the mean square displacement remain speculative. Here, we perform a set of controlled experiments that quantitatively explore the effect of spatial heterogeneities on the appearance of non-Gaussianity in Fickian diffusion. We study the diffusion of fluorescent colloidal particles in a matrix of micropillars having a range of structural configurations: from completely ordered to completely random. Structural randomness and density are found to be the two most important factors in making diffusion non-Gaussian. We show that non-Gaussianity emerges as a direct consequence of two coupled factors. First, individual particle diffusivities become spatially dependent in a heterogeneous environment. Second, the spatial distribution of the particles varies significantly in heterogeneous environments, which further influences the diffusivity of a single particle. As a result, we find that considerable non-Gaussianity appears even for weak disorder in the arrangement of the micropillars. A simple simulation validates our hypothesis that non-Gaussian yet Fickian diffusion in our system arises from the superstatistical behavior of the ensemble in a structurally heterogeneous environment. The two mechanisms identified here are relevant for many systems of crowded heterogeneous environments where non-Gaussian diffusion is frequently observed, for example in biological systems, polymers, gels and porous materials. PACS numbers: 82.70.Dd, 05.40.-a, 47.56.+rEinsteins theory of Brownian motion shows that for colloidal particles diffusing in two-dimensions in a homogenous, Newtonian fluid, the mean square displacement (MSD) is given by MSD = 4Dτ where D is the diffusion coefficient and τ is the lag time. The solution of the diffusion equation is obtained as a Gaussian probability distribution of displacements (G(∆x)) as is expected for random, independent displacements. However, in many systems including granular materials [1], turbulent flow [2], active gels [3], glassy materials [4], porous materials [5,6], nanoparticles diffusing in polymer melt [7], log-return of stock prices [8] and biological systems [9-13], a non-Gaussian G(∆x) has been observed. In many of these systems the non-Gaussian nature of G(∆x) is related to a process of anomalous diffusion. In such cases the MSD itself is non-linear in time and given by MSD = 4Dτ n , n being the diffusion exponent with a value < 1 for subdiffusion and > 1 for superdiffusion. However, in several very surprising cases, diffusion has been observed to be Fickian, that is the MSD remains linear in time, but counter-intuitively G(∆x) is non-Gaussian. This peculiar behavior has been referred to as 'Anomalous, yet Brownian' or 'Fickian yet non-Gaussian' diffusion (FNG), and has been observed in a wide variety of systems ranging from tracer colloids diffusing in suspensions of ...

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“…This unexpected observation raises awareness in the field of understanding of the material and physical properties of biological systems at the cellular level. As many current studies on the mechanical properties of bacterial and cellular cytoplasm are based on monitoring the motion and diffusion of tracers (proteins or other molecules/particles) in the organisms of interest [70][71][72][73][74][75][76][77][78][79][80][81] , it is important to pay close attention to the function of these tracer molecules/particles. As evidenced in the literature, molecules with different functions display different diffusive behaviors in E. coli bacteria [32,[70][71][72][73][74][75][76][77][78][79] , which would be translated to the differences in the material properties of the bacterial cytoplasm experienced by the molecules.…”

Section: Discussionmentioning

confidence: 99%

Faster diffusive dynamics of histone-like nucleoid structuring proteins in live bacteria caused by silver ions

Sadoon

Khadka

Freeland

et al. 2019

Preprint

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The antimicrobial activity and mechanism of silver ions (Ag + ) have gained broad attention in recent years. However, dynamic studies are rare in this field. Here, we report our measurement of the effects of Ag + ions on the dynamics of histone-like nucleoid structuring (H-NS) proteins in live bacteria using single-particle tracking photoactivated localization microscopy (sptPALM). It was found that treating the bacteria with Ag + ions led to faster diffusive dynamics of H-NS proteins. Several techniques were used to understand the mechanism of the observed faster dynamics. Electrophoretic mobility shift assay on purified H-NS proteins indicated that Ag + ions weaken the binding between H-NS proteins and DNA. Isothermal titration calorimetry confirmed that DNA and Ag + ions interact directly. Our recently developed sensing method based on bent DNA suggested that Ag + ions caused dehybridization of double-stranded DNA (i.e., dissociation into single strands). These evidences led us to a plausible mechanism for the observed faster dynamics of H-NS proteins in live bacteria when subjected to Ag + ions: Ag + -induced DNA dehybridization weakens the binding between H-NS proteins and DNA. This work highlighted the importance of dynamic study of single proteins in the live cells for understanding the functions of antimicrobial agents to the bacteria.

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$$B-S$$ B - S transition form-factors with the light-cone QCD sum rules

Cited by 44 publications

References 43 publications

Dynamics in two-dimensional glassy systems of crowded Penrose kites

Dynamics in two-dimensional glassy systems of crowded Penrose kites

Disorder-induced Fickian, yet non-Gaussian diffusion in heterogeneous media

Faster diffusive dynamics of histone-like nucleoid structuring proteins in live bacteria caused by silver ions

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