Spatial coherence of the thermal electromagnetic field in the vicinity of a dielectric slab

Lau, Wah Tung; Shen, Jung-Tsung; Veronis, Georgios; Fan, Shanhui

doi:10.1103/physreve.76.016601

Cited by 27 publications

(29 citation statements)

References 20 publications

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“…The thermal near fields associated with these surface modes can have a lateral coherence length l coh larger than the vacuum wave length 5,33 and can therefore be larger than the correlation length a considered here. However, in the quasi-static regime (d ≪ λ th ) it is found 34,35 that l coh ≈ d. Hence, for distances d ≪ a the thermally generated fields above different surface elements having an area smaller than a × a and larger than d × d are uncorrelated. Hence, for d ≪ a the flat areas can indeed be regarded as independent so that the PA is valid.…”

Section: Spectral Roughness Correctionmentioning

confidence: 98%

Influence of roughness on near-field heat transfer between two plates

Biehs

Greffet

2010

Phys. Rev. B

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The surface roughness correction to the near-field heat transfer between two rough bulk materials is discussed by using second-order perturbation theory. The results allow for estimating the impact of surface roughness to the heat transfer in recent experiments between two plates and between a micro-sphere and a plate (using the Derjaguin approximation). Furthermore, we show that the proximity approximation for describing rough surfaces is valid for distances much smaller than the correlation length of the surface roughness even if the heat transfer is dominated by the coupling of surface modes.

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Section: Spectral Roughness Correctionmentioning

confidence: 98%

Influence of roughness on near-field heat transfer between two plates

Biehs

Greffet

2010

Phys. Rev. B

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“…The mean first passage time over a one-dimensional landscape can be computed from the Fokker-Planck equation [33][34][35], appropriately modified for spatially varying diffusivity [36] (Appendix B). Specifically, the fracture time for a fixed value of r is given by…”

Section: Dynamics Over Free Energy Landscapementioning

confidence: 99%

Thermal fracture kinetics of heterogeneous semiflexible polymers

2020

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The fracture and severing of polymer chains plays a critical role in the failure of fibrous materials and the regulated turnover of intracellular filaments. Using continuum wormlike chain models, we investigate the fracture of semiflexible polymers via thermal bending fluctuations, focusing on the role of filament flexibility and dynamics. Our results highlight a previously unappreciated consequence of mechanical heterogeneity in the filament, which enhances the rate of thermal fragmentation particularly in cases where constraints hinder the movement of the chain ends. Although generally applicable to semiflexible chains with regions of different bending stiffness, the model is motivated by a specific biophysical system: the enhanced severing of actin filaments at the boundary between stiff bare regions and mechanically softened regions that are coated with cofilin regulatory proteins. The results presented here point to a potential mechanism for disassembly of polymeric materials in general and cytoskeletal actin networks in particular by the introduction of locally softened chain regions, as occurs with cofilin binding.

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“…In general, different prescriptions are possible to interpret a Langevin equation [4,48], each one affecting the value of the entropy production. The general form of the transition rates is:…”

Section: From Ito To Stratonovich Prescriptionmentioning

confidence: 99%

Entropy production in master equations and Fokker–Planck equations: facing the coarse-graining and recovering the information loss

Busiello¹,

Maritan²

2019

J. Stat. Mech.

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Systems operating out of equilibrium exchange energy and matter with the environment, thus producing entropy in their surroundings. Since the entropy production depends on the current flowing throughout the system, its quantification is affected by the level of coarse-graining we adopt. In particular, it has been shown that the description of a system via a Fokker-Planck equation (FPE) lead to an underestimation of the entropy production with respect to the corresponding one in terms of microscopic transition rates. Moreover, such a correction can be derived exactly. Here we review this derivation, generalizing it when different prescriptions to derive the FPE from a Langevin equation are adopted. Then, some open problems about Gaussian transition rates and underdamped limit are discussed. In the second part of the manuscript we present a new approach to dealing with the discrepancy in entropy production due to the coarse graining by introducing enough microscopic variables to correctly estimate the entropy production within the FPE description. We show that any discrete state system can be described by making explicit the contribution of each microscopic current. PACS numbers:A. Entropy Production for coarse-grained dynamics Different levels of description can be adopted to characterize a physical system, depending on the details we are unaware of or deliberately decided to neglect. In particular, when random variables are introduced to encode the uncontrollable degrees of freedom, the energy balance is properly captured by the concepts proper of the stochastic thermodynamics, when the system is small enough [1][2][3]. In this field, a physical system can be described using two different paradigms: Master Equation (ME) and Fokker-Planck equation (FPE) [4][5][6][7]. The former deals with the probability of occupation of each state i at time t, P i (t), and a set of microscopic transition rates between pair of states i and j, W i→j (t). It has the following form:which states the the probability to be in the state i evolves according to the balance between the ingoing and the outgoing probability flux of the state itself. Here we assume that W i→j > 0 implies W j→i > 0, which ensures the ergodicity of the system. Note that here and throughout the manuscript we set W i→i = 0 even though it never enters in the ME above.On the other hand, a Fokker-Planck equation described the system via continuous variables by means of a diffusive dynamics:x (D(x)P (x, t)) (2) where P (x, t) is the probability to be in the state x at the time t, A(x, t) is the drift coefficient and D(x, t) is called the diffusion coefficient. The continuum limit, obtained through a coarse-graining procedure, to derive the latter equation from Eq. (1) is called Kramers-Moyal expansion [4]. It relies on the assumption that the first two "pseudo"-moments [54] of the transition rates are the only ones that are non-negligible, and they are related to A and D respectively.Although the two descriptions appears be equivalent for certain aspects (e.g. equilib...

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Spatial coherence of the thermal electromagnetic field in the vicinity of a dielectric slab

Cited by 27 publications

References 20 publications

Influence of roughness on near-field heat transfer between two plates

Influence of roughness on near-field heat transfer between two plates

Thermal fracture kinetics of heterogeneous semiflexible polymers

Entropy production in master equations and Fokker–Planck equations: facing the coarse-graining and recovering the information loss

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