Special Issue "Selected Papers from 45th Conference of the Middle European Cooperation in Statistical Physics"

A special issue of Entropy (ISSN 1099-4300). This special issue belongs to the section "Statistical Physics".

Deadline for manuscript submissions: closed (1 March 2021) | Viewed by 7121

Special Issue Editors

Prof. Zoltán Néda
E-Mail Website
Guest Editor
Department of Theoretical and Computational Physics, Babes-Bolyai University, Cluj-Napoca 400084, Romania
Interests: interdisciplinary applications of statistical physics; scaling; complex systems; synchronization
Dr. Bulcsu Sandor
E-Mail Website
Guest Editor
Department of Physics, Babes-Bolyai University, 400084 Cluj-Napoca, Romania
Interests: dynamical systems; econo-physics; synchronization; collective behavior
Dr. Maria Ercsey-Ravasz
E-Mail Website
Guest Editor
Faculty of Physics, Babes-Bolyai University, 400084 Cluj-Napoca, Romania
Interests: complex networks; dynamical systems; neuroscience; scientometrics

Special Issue Information

Dear Colleagues,

The MECO meetings are yearly surveys for the novel results related to statistical physics. In general, contributions to these conferences have a wide spectrum ranging from the classical models and methods of statistical physics to modern interdisciplinary applications. Depending on the research specialization of the organizing institutes the meeting might focus also on a more clearly defined topic, without being restricted to other contributions. The 2020 MECO45 meeting is therefore focusing on complex systems and their methods of study that are inspired by statistical physics. Simple and complex models of statistical physics, it's analytical and/or numerical methods have proven to be helpful and successful in tackling the complexity of the world around us. The main topics covered by most of the keynote and invited talks are related to either models or methods. Besides the popular fields of complex networks, dynamical systems, emergence, econo- and socio-physics, phase-transitions and pattern formation we also expect contributions tackling other novel problems, models and methods that are not directly related to the above problems. For the present conference, we propose thus to edit the special issue in two directions, one focusing on general contributions in all the fields related to statistical physics and the other closely related to complex systems. For the second direction targeting complex systems we intend to invite also contributions from well-known researchers who will not have the opportunity to join us at the MECO 45 meeting in Cluj-Napoca. Submission of contributions to this special issue is encouraged for all participants of the MECO 45 conference (http://atom.ubbcluj.ro/meco45/).

 

Prof. Zoltán Néda
Dr. Bulcsu Sandor
Dr. Maria Ercsey-Ravasz
Guest Editors

Manuscript Submission Information

Manuscripts should be submitted online at www.mdpi.com by registering and logging in to this website. Once you are registered, click here to go to the submission form. Manuscripts can be submitted until the deadline. All submissions that pass pre-check are peer-reviewed. Accepted papers will be published continuously in the journal (as soon as accepted) and will be listed together on the special issue website. Research articles, review articles as well as short communications are invited. For planned papers, a title and short abstract (about 100 words) can be sent to the Editorial Office for announcement on this website.

Submitted manuscripts should not have been published previously, nor be under consideration for publication elsewhere (except conference proceedings papers). All manuscripts are thoroughly refereed through a single-blind peer-review process. A guide for authors and other relevant information for submission of manuscripts is available on the Instructions for Authors page. Entropy is an international peer-reviewed open access monthly journal published by MDPI.

Please visit the Instructions for Authors page before submitting a manuscript. The Article Processing Charge (APC) for publication in this open access journal is 1800 CHF (Swiss Francs). Submitted papers should be well formatted and use good English. Authors may use MDPI's English editing service prior to publication or during author revisions.

Keywords

  • methods and models of statistical physics
  • interdisciplinary applications of statistical physics
  • emergence, scaling, complex systems

Published Papers (8 papers)

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Article
Fluctuating Diffusivity of RNA-Protein Particles: Analogy with Thermodynamics
Entropy 2021, 23(3), 333; https://doi.org/10.3390/e23030333 - 12 Mar 2021
Cited by 1 | Viewed by 869
Abstract
A formal analogy of fluctuating diffusivity to thermodynamics is discussed for messenger RNA molecules fluorescently fused to a protein in living cells. Regarding the average value of the fluctuating diffusivity of such RNA-protein particles as the analog of the internal energy, the analogs [...] Read more.
A formal analogy of fluctuating diffusivity to thermodynamics is discussed for messenger RNA molecules fluorescently fused to a protein in living cells. Regarding the average value of the fluctuating diffusivity of such RNA-protein particles as the analog of the internal energy, the analogs of the quantity of heat and work are identified. The Clausius-like inequality is shown to hold for the entropy associated with diffusivity fluctuations, which plays a role analogous to the thermodynamic entropy, and the analog of the quantity of heat. The change of the statistical fluctuation distribution is also examined from a geometric perspective. The present discussions may contribute to a deeper understanding of the fluctuating diffusivity in view of the laws of thermodynamics. Full article
Article
Transient Dynamics in the Random Growth and Reset Model
Entropy 2021, 23(3), 306; https://doi.org/10.3390/e23030306 - 05 Mar 2021
Cited by 3 | Viewed by 745
Abstract
A mean-field type model with random growth and reset terms is considered. The stationary distributions resulting from the corresponding master equation are relatively easy to obtain; however, for practical applications one also needs to know the convergence to stationarity. The present work contributes [...] Read more.
A mean-field type model with random growth and reset terms is considered. The stationary distributions resulting from the corresponding master equation are relatively easy to obtain; however, for practical applications one also needs to know the convergence to stationarity. The present work contributes to this direction, studying the transient dynamics in the discrete version of the model by two different approaches. The first method is based on mathematical induction by the recursive integration of the coupled differential equations for the discrete states. The second method transforms the coupled ordinary differential equation system into a partial differential equation for the generating function. We derive analytical results for some important, practically interesting cases and discuss the obtained results for the transient dynamics. Full article
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Article
Investigation of Ring and Star Polymers in Confined Geometries: Theory and Simulations
Entropy 2021, 23(2), 242; https://doi.org/10.3390/e23020242 - 19 Feb 2021
Cited by 1 | Viewed by 807 | Correction
Abstract
The calculations of the dimensionless layer monomer density profiles for a dilute solution of phantom ideal ring polymer chains and star polymers with f=4 arms in a Θ-solvent confined in a slit geometry of two parallel walls with repulsive surfaces [...] Read more.
The calculations of the dimensionless layer monomer density profiles for a dilute solution of phantom ideal ring polymer chains and star polymers with f=4 arms in a Θ-solvent confined in a slit geometry of two parallel walls with repulsive surfaces and for the mixed case of one repulsive and the other inert surface were performed. Furthermore, taking into account the Derjaguin approximation, the dimensionless layer monomer density profiles for phantom ideal ring polymer chains and star polymers immersed in a solution of big colloidal particles with different adsorbing or repelling properties with respect to polymers were calculated. The density-force relation for the above-mentioned cases was analyzed, and the universal amplitude ratio B was obtained. Taking into account the small sphere expansion allowed obtaining the monomer density profiles for a dilute solution of phantom ideal ring polymers immersed in a solution of small spherical particles, or nano-particles of finite size, which are much smaller than the polymer size and the other characteristic mesoscopic length of the system. We performed molecular dynamics simulations of a dilute solution of linear, ring, and star-shaped polymers with N=300, 300 (360), and 1201 (4 × 300 + 1-star polymer with four arms) beads accordingly. The obtained analytical and numerical results for phantom ring and star polymers are compared with the results for linear polymer chains in confined geometries. Full article
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Article
Collective Strategy Condensation: When Envy Splits Societies
Entropy 2021, 23(2), 157; https://doi.org/10.3390/e23020157 - 27 Jan 2021
Viewed by 640
Abstract
Human societies are characterized by three constituent features, besides others. (A) Options, as for jobs and societal positions, differ with respect to their associated monetary and non-monetary payoffs. (B) Competition leads to reduced payoffs when individuals compete for the same option as others. [...] Read more.
Human societies are characterized by three constituent features, besides others. (A) Options, as for jobs and societal positions, differ with respect to their associated monetary and non-monetary payoffs. (B) Competition leads to reduced payoffs when individuals compete for the same option as others. (C) People care about how they are doing relatively to others. The latter trait—the propensity to compare one’s own success with that of others—expresses itself as envy. It is shown that the combination of (A)–(C) leads to spontaneous class stratification. Societies of agents split endogenously into two social classes, an upper and a lower class, when envy becomes relevant. A comprehensive analysis of the Nash equilibria characterizing a basic reference game is presented. Class separation is due to the condensation of the strategies of lower-class agents, which play an identical mixed strategy. Upper-class agents do not condense, following individualist pure strategies. The model and results are size-consistent, holding for arbitrary large numbers of agents and options. Analytic results are confirmed by extensive numerical simulations. An analogy to interacting confined classical particles is discussed. Full article
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Article
A Novel Measure Inspired by Lyapunov Exponents for the Characterization of Dynamics in State-Transition Networks
Entropy 2021, 23(1), 103; https://doi.org/10.3390/e23010103 - 12 Jan 2021
Cited by 2 | Viewed by 1208
Abstract
The combination of network sciences, nonlinear dynamics and time series analysis provides novel insights and analogies between the different approaches to complex systems. By combining the considerations behind the Lyapunov exponent of dynamical systems and the average entropy of transition probabilities for Markov [...] Read more.
The combination of network sciences, nonlinear dynamics and time series analysis provides novel insights and analogies between the different approaches to complex systems. By combining the considerations behind the Lyapunov exponent of dynamical systems and the average entropy of transition probabilities for Markov chains, we introduce a network measure for characterizing the dynamics on state-transition networks with special focus on differentiating between chaotic and cyclic modes. One important property of this Lyapunov measure consists of its non-monotonous dependence on the cylicity of the dynamics. Motivated by providing proper use cases for studying the new measure, we also lay out a method for mapping time series to state transition networks by phase space coarse graining. Using both discrete time and continuous time dynamical systems the Lyapunov measure extracted from the corresponding state-transition networks exhibits similar behavior to that of the Lyapunov exponent. In addition, it demonstrates a strong sensitivity to boundary crisis suggesting applicability in predicting the collapse of chaos. Full article
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Article
Butterfly Effect in Chaotic Image Segmentation
Entropy 2020, 22(9), 1028; https://doi.org/10.3390/e22091028 - 15 Sep 2020
Cited by 5 | Viewed by 1122
Abstract
The exploitation of the important features exhibited by the complex systems found in the surrounding natural and artificial space will improve computational model performance. Therefore, the purpose of the current paper is to use cellular automata as a tool simulating complexity, able to [...] Read more.
The exploitation of the important features exhibited by the complex systems found in the surrounding natural and artificial space will improve computational model performance. Therefore, the purpose of the current paper is to use cellular automata as a tool simulating complexity, able to bring forth an interesting global behaviour based only on simple, local interactions. We show that, in the context of image segmentation, a butterfly effect arises when we perturb the neighbourhood system of a cellular automaton. Specifically, we enhance a classical GrowCut cellular automaton with chaotic features, which are also able to improve its performance (e.g., a Dice coefficient of 71% in case of 2D images). This enhanced GrowCut flavor (referred to as Band-Based GrowCut) uses an extended, stochastic neighbourhood, in which randomly-selected remote neighbours reinforce the standard local ones. We demonstrate the presence of the butterfly effect and an increase in segmentation performance by numerical experiments performed on synthetic and natural images. Thus, our results suggest that, by having small changes in the initial conditions of the performed task, we can induce major changes in the final outcome of the segmentation. Full article
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Correction
Correction: Halun et al. Investigation of Ring and Star Polymers in Confined Geometries: Theory and Simulations. Entropy 2021, 23, 242
Entropy 2022, 24(3), 413; https://doi.org/10.3390/e24030413 - 16 Mar 2022
Viewed by 315
Abstract
The authors wish to make the following correction to this paper [...] Full article
Conference Report
Knotting the MECO Network
Entropy 2021, 23(2), 141; https://doi.org/10.3390/e23020141 - 24 Jan 2021
Viewed by 792
Abstract
The Conferences of the Middle European Cooperation in Statistical Physics (MECO) were created as an attempt to establish and maintain an exchange between scientists in the fields of statistical and condensed matter physics from Western and Eastern countries, overcoming the hurdles of the [...] Read more.
The Conferences of the Middle European Cooperation in Statistical Physics (MECO) were created as an attempt to establish and maintain an exchange between scientists in the fields of statistical and condensed matter physics from Western and Eastern countries, overcoming the hurdles of the Iron Curtain. Based on personal remembrance and historical resources, the genesis and further development of MECO meetings is described. The annual meetings were interrupted in 1991 by the Yugoslav War but were re-established in 1993 and continue today. Although the fall of the Iron Curtain and the European Research programs changed the situation for the meetings considerably, the ties created by MECO still are useful to help scientific exchange. The history of European (and not only) statistical physics and the history of the MECO are tightly intertwined. It started in a time where an essential breakthrough has been achieved in statistical physics describing the features near phase transitions. In addition to the merging of solid-state physics and field theory concepts, the application of numerical methods (Monte Carlo methods) added a new pillar besides exact solutions and experiments to check theoretical models. In the following, the scientific emphasis (in general) has changed from the traditional fields of the first MECO to complexity and interdisciplinary themes as well. Full article
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