References of "Europhysics Letters"
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See detailActive engines: Thermodynamics moves forward
Fodor, Etienne UL; Cates, Michael E.

in Europhysics Letters (2021), 134

The study of thermal heat engines was pivotal to establishing the principles of equilibrium thermodynamics, with implications far wider than only engine optimization. For nonequilibrium systems, which by ... [more ▼]

The study of thermal heat engines was pivotal to establishing the principles of equilibrium thermodynamics, with implications far wider than only engine optimization. For nonequilibrium systems, which by definition dissipate energy even at rest, how to best convert such dissipation into useful work is still largely an outstanding question, with similar potential to illuminate general physical principles. We review recent theoretical progress in studying the performances of engines operating with active matter, where particles are driven by individual self-propulsion. We distinguish two main classes, either autonomous engines exploiting a particle current, or cyclic engines applying periodic transformation to the system, and present the strategies put forward so far for optimization. We delineate the limitations of previous studies, and propose some future perspectives, with a view to building a consistent thermodynamic framework far from equilibrium. [less ▲]

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See detailNon-Markovian out-of-equilibrium dynamics: A general numerical procedure to construct time-dependent memory kernels for coarse-grained observables
Meyer, Hugues UL; Pelagejcev, Philipp; Schilling, Tanja

in Europhysics Letters (2020), 128(4), 40001

We present a numerical method to compute non-equilibrium memory kernels based on experimental data or molecular dynamics simulations. The procedure uses a recasting of the non-stationary generalized ... [more ▼]

We present a numerical method to compute non-equilibrium memory kernels based on experimental data or molecular dynamics simulations. The procedure uses a recasting of the non-stationary generalized Langevin equation, in which we expand the memory kernel in a series that can be reconstructed iteratively. Each term in the series can be computed based solely on knowledge of the two-time auto-correlation function of the observable of interest. We discuss how to optimize this method in order to be the most numerically convenient. As a proof of principle, we test the method on the problem of crystallization from a super-cooled Lennard-Jones melt. We analyze the nucleation and growth dynamics of crystallites and observe that the memory kernel has a time extent that is about one order of magnitude larger than the typical timescale needed for a particle to be attached to the crystallite in the growth regime. [less ▲]

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See detailCation distribution of Mn-Zn ferrite nanoparticles using pair distribution function analysis and resonant X-ray scattering
Ichikawa, Rodrigo U; Parra, João PRLL; Vallcorba, Oriol et al

in Europhysics Letters (2018)

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See detailCarnot efficiency at divergent power output
Polettini, Matteo UL; Esposito, Massimiliano UL

in Europhysics Letters (2017), 118(40003),

The widely debated feasibility of thermodynamic machines achieving Carnot efficiency at finite power has been convincingly dismissed. Yet, the common wisdom that efficiency can only be optimal in the ... [more ▼]

The widely debated feasibility of thermodynamic machines achieving Carnot efficiency at finite power has been convincingly dismissed. Yet, the common wisdom that efficiency can only be optimal in the limit of infinitely slow processes overlooks the dual scenario of infinitely fast processes. We corroborate that efficient engines at divergent power output are not theoretically impossible, framing our claims within the theory of Stochastic Thermodynamics. We inspect the case of an electronic quantum dot coupled to three particle reservoirs to illustrate the physical rationale. [less ▲]

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See detailSequencing chess
atashpendar, Arshia; Schilling, Tanja UL; Voigtmann, Thomas

in Europhysics Letters (2016), 116(10009),

We analyze the structure of the state space of chess by means of transition path sampling Monte Carlo simulations. Based on the typical number of moves required to transpose a given configuration of chess ... [more ▼]

We analyze the structure of the state space of chess by means of transition path sampling Monte Carlo simulations. Based on the typical number of moves required to transpose a given configuration of chess pieces into another, we conclude that the state space consists of several pockets between which transitions are rare. Skilled players explore an even smaller subset of positions that populate some of these pockets only very sparsely. These results suggest that the usual measures to estimate both the size of the state space and the size of the tree of legal moves are not unique indicators of the complexity of the game, but that considerations regarding the connectedness of states are equally important. [less ▲]

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See detailDissipation by a crystallization process
Dorosz, Sven UL; Voigtmann, Thomas; Schilling, Tanja UL

in Europhysics Letters (2016), 113(10004),

We discuss crystallization as a non-equilibrium process. In a system of hard spheres under compression at a constant rate, we quantify the amount of heat that is dissipated during the crystallization ... [more ▼]

We discuss crystallization as a non-equilibrium process. In a system of hard spheres under compression at a constant rate, we quantify the amount of heat that is dissipated during the crystallization process. We interpret the dissipation as arising from the resistance of the system against phase transformation. An intrinsic compression rate is identified that separates a quasistatic regime from one of rapidly driven crystallization. In the latter regime the system crystallizes more easily, because new relaxation channels are opened, at the cost of forming a higher fraction of non-equilibrium crystal structures. We rationalize the change in the crystallization mechanism by analogy with shear thinning, in terms of a kinetic competition between near-equilibrium relaxation and external driving. [less ▲]

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See detailPercolation in suspensions of hard nanoparticules: From Spheres to needles
Schilling, Tanja UL; Miller, Mark A.; Van der Schoot, Paul

in Europhysics Letters (2015), 111

We investigate geometric percolation and scaling relations in suspensions of nanorods, covering the entire range of aspect ratios from spheres to extremely slender needles. A new version of connectedness ... [more ▼]

We investigate geometric percolation and scaling relations in suspensions of nanorods, covering the entire range of aspect ratios from spheres to extremely slender needles. A new version of connectedness percolation theory is introduced and tested against specialised Monte Carlo simulations. The theory accurately predicts percolation threshold for aspect ratios of length to width as low as 10. The percolation threshold for rod-like particules of aspect ratios below 1000 deviates significantly from the inverse aspect ratio scaling prediction, thought to be valid in the limit of infinitely slender rods and often used as a rule of thumb for nanofibres in composites materials. Hence, most fibres that are currently used as fillers in composite materials cannot be regarded as pratically infinitely slender for the purposes of percolation theory. Comparing percolation thresholds of hard rods and new benchmark results for ideal rods, we find that i) for large aspect ratios, they differ by a factor that is inversely proportional to the connectivity distance between the hard cores, and ii) they approach the slender rod limit differently. [less ▲]

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See detailNon-universal Voronoi cell shapes in amorphous ellipsoid packs
Schaller, Fabian M; Kapfer, Sebastian C; Hilton, James E. et al

in Europhysics Letters (2015), 111

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See detailSolvent hydrodynamics speed up crystal nucleation in suspensions of hard spheres
Radu, Marc UL; Schilling, Tanja UL

in Europhysics Letters (2014), 105

We present a computer simulation study on the crystal nucleation process in suspensions of hard spheres, fully taking into account the solvent hydrodynamics. If the dynamics of crystallization in this ... [more ▼]

We present a computer simulation study on the crystal nucleation process in suspensions of hard spheres, fully taking into account the solvent hydrodynamics. If the dynamics of crystallization in this system were purely diffusive, the crystal nucleation rate would be inversely proportional to the solvent viscosity. However, we observe that the nucleation rate is enhanced at high viscosities with respect to the diffusive behaviour. This effect might explain the large discrepancy between the nuclation rates obtained by simulation and experiment that have been reported in the literature so far. [less ▲]

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See detailStochastic thermodynamics for “Maxwell demon” feedbacks
Esposito, Massimiliano UL; Schaller, Gernot

in Europhysics Letters (2012), 99(30003),

We propose a way to incorporate the effect of a specific class of feedback processes into <br /><br />stochastic thermodynamics. These “Maxwell demon” feedbacks do not affect the system energetics <br ... [more ▼]

We propose a way to incorporate the effect of a specific class of feedback processes into <br /><br />stochastic thermodynamics. These “Maxwell demon” feedbacks do not affect the system energetics <br /><br />but only the energy barriers between the system states (in a way which depends on the system <br /><br />states). They are thus of a purely informational nature. We show that the resulting formalism can <br /><br />be applied to study the thermodynamic effect of a feedback process acting on electron transfers <br /><br />through a junction. [less ▲]

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See detailSocio-economic utility and chemical potential
Lemoy, Rémi UL; Bertin, Eric; Jensen, Pablo

in Europhysics Letters (2011), 93(3), 38002-6

In statistical physics, the conservation of particle number results in the equalization of the chemical potential throughout a system at equilibrium. In contrast, the homogeneity of utility in socio ... [more ▼]

In statistical physics, the conservation of particle number results in the equalization of the chemical potential throughout a system at equilibrium. In contrast, the homogeneity of utility in socio-economic models is usually thought to rely on the competition between individuals, leading to Nash equilibrium. We show that both views can be reconciled by introducing a notion of chemical potential in a wide class of socio-economic models, and by relating it in a direct way to the equilibrium value of the utility. This approach also allows the dependence of utility across the system to be determined when agents take decisions in a probabilistic way. Numerical simulations of a urban economic model also suggest that our result is valid beyond the initially considered class of solvable models. Copyright (C) EPLA, 2011 [less ▲]

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See detailModified fluctuation-dissipation theorem for non-equilibrium steady states and applications to molecular motors
Verley, Gatien UL; Mallick, K.; Lacoste, D.

in Europhysics Letters (2011), 93(1), 10002

We present a theoretical framework to understand a modified fluctuation-dissipation theorem valid for systems close to non-equilibrium steady states and obeying Markovian dynamics. We discuss the ... [more ▼]

We present a theoretical framework to understand a modified fluctuation-dissipation theorem valid for systems close to non-equilibrium steady states and obeying Markovian dynamics. We discuss the interpretation of this result in terms of trajectory entropy excess. The framework is illustrated on a simple pedagogical example of a molecular motor. We also derive in this context generalized Green-Kubo relations similar to the ones obtained recently in Seifert U., Phys. Rev. Lett., 104 (2010) 138101 for more general networks of biomolecular states. [less ▲]

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See detailPolymer-induced phase separation in suspensions of bacteria
Schwarz-Linek, J.; Dorken, G.; Winkler, A. et al

in Europhysics Letters (2010), 89

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See detailPorosity-induced spin disorder in nanocrystalline inert-gas condensed iron
Michels, Andreas UL; Elmas, M.; Döbrich, Frank UL et al

in Europhysics Letters (2009), 85

We report magnetization and magnetic neutron scattering measurements on nanocrystalline Fe which was prepared by means of the inert-gas condensation technique. Depending on the compaction pressure applied ... [more ▼]

We report magnetization and magnetic neutron scattering measurements on nanocrystalline Fe which was prepared by means of the inert-gas condensation technique. Depending on the compaction pressure applied during the synthesis procedure (0.5–1.8 GPa), the resulting Fe samples contain porosity with volume fractions between about 20–35%. We provide evidence that the spin disorder which is associated with porosity has a strong influence on magnetic properties, and it gives rise to a characteristic clover-leaf–shaped angular anisotropy in the elastic-magnetic-scattering cross-section. [less ▲]

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See detailGlassy dynamics in monodisperse hard ellipsoids
Pfleiderer, P.; Milinkovic, K.; Schilling, Tanja UL

in Europhysics Letters (2008), 84(1),

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See detailSpin structure of nanocrystalline gadolinium
Michels, Andreas UL; Döbrich, Frank UL; Elmas, M. et al

in Europhysics Letters (2008), 81

We report on magnetic-field–dependent small-angle neutron scattering (SANS) experiments on nanocrystalline inert-gas condensed bulk Gd, which was synthesized using the low-capturing isotope 160Gd. The ... [more ▼]

We report on magnetic-field–dependent small-angle neutron scattering (SANS) experiments on nanocrystalline inert-gas condensed bulk Gd, which was synthesized using the low-capturing isotope 160Gd. The angular dependency of the scattering cross-section is in very good agreement with recent theoretical predictions. Rather unexpected for this type of material, we observe a "clover-leaf–shaped" anisotropy in the SANS signal, the origin of which is attributed to the existence of longitudinal magnetization fluctuations associated with atomic site disorder and modified coupling inside the defect cores of grain boundaries. [less ▲]

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See detailDipole-field-induced spin disorder in a nanocomposite soft magnet
Michels, Andreas UL; Vecchini, C.; Moze, O. et al

in Europhysics Letters (2005), 72(2), 249-255

We report on a study of a magnetic nanocomposite of the Nanoperm type (Fe89Zr7B3Cu1) by magnetic small-angle neutron scattering (SANS). The understanding of the magnetic microstructure of these materials ... [more ▼]

We report on a study of a magnetic nanocomposite of the Nanoperm type (Fe89Zr7B3Cu1) by magnetic small-angle neutron scattering (SANS). The understanding of the magnetic microstructure of these materials leaves much to be desired since we lack techniques capable of resolving the spin structure in the bulk with nanoscale resolution. Here, we present an analysis of the SANS signal by which one cannot only characterise the nanoscale structure of the spin system, but which allows to identify origin and structure of the perturbing field. In Nanoperm, an unusual angular anisotropy of the scattering suggests that the local spin misalignment decorates, as the most important perturbing field, dipole stray fields around the crystalline phase of the composite. [less ▲]

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See detailDissipative quantum dynamics in terms of a reduced density matrix distributed over the environment energy
Esposito, Massimiliano UL; Gaspard, P.

in Europhysics Letters (2004), 65(6),

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See detailDomain formation and long-range spin disorder in Vitroperm
Michels, Andreas UL; Viswanath, R. N.; Weissmüller, J.

in Europhysics Letters (2003), 64

We present a study of the magnetic-field dependence of the small-angle neutron scattering of the nanocrystalline soft magnet Vitroperm (Fe73Si16B7Nb3Cu1), which was treated so as to exhibit a macroscopic ... [more ▼]

We present a study of the magnetic-field dependence of the small-angle neutron scattering of the nanocrystalline soft magnet Vitroperm (Fe73Si16B7Nb3Cu1), which was treated so as to exhibit a macroscopic magnetic anisotropy. We show how the field dependences of i) the radial average of the scattering cross-section dΣ/dΩ and ii) the variation of dΣ/dΩ as a function of the orientation of the scattering vector can be analysed to supply separately information on the orientation of the net magnetisation of the domains and on the internal spin disorder within the domains. As the applied magnetic field is decreased starting from saturation, we find that two processes occur independently: the formation of a domain structure with the net magnetisation of the domains aligned along the macroscopic easy axis and the increase in magnitude of static, nanometer-scale fluctuations of the spin orientation. [less ▲]

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