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G. De Ninno - One of the best experts on this subject based on the ideXlab platform.
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Out-of-equilibrium Statistical Ensemble inequivalence
EPL, 2012Co-Authors: G. De Ninno, Duccio FanelliAbstract:We consider a paradigmatic model describing the one-dimensional motion of N rotators coupled through a mean-field interaction, and subject to the perturbation of an external magnetic field. The latter is shown to significantly alter the system behaviour, driving the emergence of Ensemble inequivalence in the out-of-equilibrium phase, as signalled by a negative (microcanonical) magnetic susceptibility. The thermodynamic of the system is analytically discussed, building on a maximum-entropy scheme justified from first principles. Simulations confirm the adequacy of the theoretical picture. Ensemble inequivalence is shown to rely on a peculiar phenomenon, different from the one observed in previous works. As a result, the existence of a convex intruder in the entropy is found to be a necessary but not sufficient condition for inequivalence to be (macroscopically) observed. Negative-temperature states are also found to occur. These intriguing phenomena reflect the non-Boltzmanian nature of the scrutinized problem and, as such, bear traits of universality that embrace equilibrium as well as out-of-equilibrium regimes.
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Negative specific heat in the canonical Statistical Ensemble
arXiv: Statistical Mechanics, 2011Co-Authors: F. Staniscia, Alessandro Turchi, Pierre-henri Chavanis, Duccio Fanelli, G. De NinnoAbstract:1. Dipartimento di Fisica, Universita` di Trieste, Italy2. Sincrotrone Trieste, S.S. 14 km 163.5, Basovizza (Ts), Italy3. Dipartimento di Sistemi e Informatica, Universita` di Firenze, via S. Marta 3, 50139 Firenze, Italy4. Dipartimento di Energetica “Sergio Stecco”, Universit`a di Firenze, via S. Marta 3, 50139 Firenze, Italy5. Universit´e de Toulouse, UPS, Laboratoire de Physique Th´eorique (IRSAMC), F-31062 Toulouse, France6. CNRS, Laboratoire de Physique Th´eorique (IRSAMC), F-31062 Toulouse, France7. Physics Department, Nova Gorica University, Nova Gorica, Slovenia
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Out of equilibrium Statistical Ensemble inequivalence
arXiv: Statistical Mechanics, 2010Co-Authors: G. De Ninno, Duccio FanelliAbstract:We consider a paradigmatic model describing the one-dimensional motion of $N$ rotators coupled through a mean-field interaction, and subject to the perturbation of an external magnetic field. The latter is shown to significantly alter the system behaviour, driving the emergence of Ensemble inequivalence in the out-of-equilibrium phase, as signalled by a negative (microcanonical) magnetic susceptibility. The thermodynamic of the system is analytically discussed, building on a maximum entropy scheme justified from first principles. Simulations confirm the adequacy of the theoretical picture. Ensemble inequivalence is shown to rely on a peculiar phenomenon, different from the one observed in previous works. As a result, the existence of a convex intruder in the micro-canonical energy is found to be a necessary but not sufficient condition for inequivalence to be (macroscopically) observed. Negative temperature states are also found to occur. These intriguing phenomena reflect the non-Boltzmanian nature of the scrutinized problem and, as such, bear traits of universality that embraces equilibrium as well out-of-equilibrium regimes.
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Negative Specific Heat in the Canonical Statistical Ensemble
Physical Review Letters, 2010Co-Authors: F. Staniscia, Alessandro Turchi, Pierre-henri Chavanis, Daniele Fanelli, G. De NinnoAbstract:According to thermodynamics, the specific heat of Boltzmannian short-range interacting systems is a positive quantity. Less intuitive properties are instead displayed by systems characterized by long-range interactions. In that case, the sign of specific heat depends on the considered Statistical Ensemble: negative specific heat can be found in isolated systems, which are studied in the framework of the microcanonical Ensemble; on the other hand, it is generally recognized that a positive specific heat should always be measured in systems in contact with a thermal bath, for which the canonical Ensemble is the appropriate one. We demonstrate that the latter assumption is not generally true: one can in principle measure negative specific heat also in the canonical Ensemble if the system under scrutiny is non-Boltzmannian and/or out-of-equilibrium.
Abdul Salam Jarrah - One of the best experts on this subject based on the ideXlab platform.
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Statistical Ensemble of gene regulatory networks of macrophage differentiation
BMC Bioinformatics, 2016Co-Authors: Filippo Castiglione, Paolo Tieri, Alessandro Palma, Abdul Salam JarrahAbstract:Background Macrophages cover a major role in the immune system, being the most plastic cell yielding several key immune functions. Methods Here we derived a minimalistic gene regulatory network model for the differentiation of macrophages into the two phenotypes M1 (pro-) and M2 (anti-inflammatory). Results To test the model, we simulated a large number of such networks as in a Statistical Ensemble. In other words, to enable the inter-cellular crosstalk required to obtain an immune activation in which the macrophage plays its role, the simulated networks are not taken in isolation but combined with other cellular agents, thus setting up a discrete minimalistic model of the immune system at the microscopic/intracellular (i.e., genetic regulation) and mesoscopic/intercellular scale. Conclusions We show that within the mesoscopic level description of cellular interaction and cooperation, the gene regulatory logic is coherent and contributes to the overall dynamics of the Ensembles that shows, Statistically, the expected behaviour.
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Statistical Ensemble of gene regulatory networks of macrophage differentiation.
BMC bioinformatics, 2016Co-Authors: Filippo Castiglione, Paolo Tieri, Alessandro Palma, Abdul Salam JarrahAbstract:Macrophages cover a major role in the immune system, being the most plastic cell yielding several key immune functions. Here we derived a minimalistic gene regulatory network model for the differentiation of macrophages into the two phenotypes M1 (pro-) and M2 (anti-inflammatory). To test the model, we simulated a large number of such networks as in a Statistical Ensemble. In other words, to enable the inter-cellular crosstalk required to obtain an immune activation in which the macrophage plays its role, the simulated networks are not taken in isolation but combined with other cellular agents, thus setting up a discrete minimalistic model of the immune system at the microscopic/intracellular (i.e., genetic regulation) and mesoscopic/intercellular scale. We show that within the mesoscopic level description of cellular interaction and cooperation, the gene regulatory logic is coherent and contributes to the overall dynamics of the Ensembles that shows, Statistically, the expected behaviour.
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Statistical Ensemble of gene regulatory networks of macrophage differentiation
BMC Bioinformatics, 2016Co-Authors: Filippo Castiglione, Paolo Tieri, Alessandro Palma, Abdul Salam JarrahAbstract:Background Macrophages cover a major role in the immune system, being the most plastic cell yielding several key immune functions.
Freddy Bouchet - One of the best experts on this subject based on the ideXlab platform.
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Statistical Ensemble Inequivalence and Bicritical Points for Two-Dimensional Flows and Geophysical Flows
Physical Review Letters, 2009Co-Authors: Antoine Venaille, Freddy BouchetAbstract:A theoretical description for the equilibrium states of a large class of models of two-dimensional and geophysical flows is presented. A Statistical Ensemble equivalence is found to exist generically in these models, related to the occurrence of peculiar phase transitions in the flow topology. The first example of a bicritical point (a bifurcation from a first toward two second order phase transitions) in the context of systems with long-range interactions is reported. Academic ocean models, the Fofonoff flows, are studied in the perspective of these results.
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Statistical mechanics and long range interactions
Comptes Rendus Physique, 2006Co-Authors: Julien Barré, Freddy BouchetAbstract:We briefly review the classical approach to equilibrium and out of equilibrium Statistical mechanics of long range interacting systems, for which the energy is not additive, and emphasize some new results. At equilibrium, we explain the thermodynamic consequences of the lack of additivity, like the generic occurrence of Statistical Ensemble inequivalence and negative specific heat. We then present a recent new classification of phase transitions and Ensemble inequivalence in systems with long range interactions, and note a number of generic situations that have not yet been observed in any physical systems. Out of equilibrium, we show that algebraic temporal correlations or anomalous diffusion may occur in these systems, and can be explained using usual Statistical mechanics and kinetic theory.
Martin Land - One of the best experts on this subject based on the ideXlab platform.
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The Particle as a Statistical Ensemble of Events in Stueckelberg–Horwitz–Piron Electrodynamics
Entropy, 2017Co-Authors: Martin LandAbstract:In classical Maxwell electrodynamics, charged particles following deterministic trajectories are described by currents that induce fields, mediating interactions with other particles. Statistical methods are used when needed to treat complex particle and/or field configurations. In Stueckelberg–Horwitz–Piron (SHP) electrodynamics, the classical trajectories are traced out dynamically, through the evolution of a 4D spacetime event x μ ( τ ) as τ grows monotonically. Stueckelberg proposed to formalize the distinction between coordinate time x 0 = c t (measured by laboratory clocks) and chronology τ (the temporal ordering of event occurrence) in order to describe antiparticles and resolve problems of irreversibility such as grandfather paradoxes. Consequently, in SHP theory, the elementary object is not a particle (a 4D curve in spacetime) but rather an event (a single point along the dynamically evolving curve). Following standard deterministic methods in classical relativistic field theory, one is led to Maxwell-like field equations that are τ -dependent and sourced by a current that represents a Statistical Ensemble of instantaneous events distributed along the trajectory. The width λ of this distribution defines a correlation time for the interactions and a mass spectrum for the photons emitted by particles. As λ becomes very large, the photon mass goes to zero and the field equations become τ -independent Maxwell’s equations. Maxwell theory thus emerges as an equilibrium limit of SHP, in which λ is larger than any other relevant time scale. Thus, Statistical mechanics is a fundamental ingredient in SHP electrodynamics, and its insights are required to give meaning to the concept of a particle.
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The Particle as a Statistical Ensemble of Events in Stueckelberg-Horwitz-Piron Electrodynamics †
2017Co-Authors: Martin LandAbstract:Stueckelberg-Horwitz-Piron (SHP) electrodynamics formalizes the distinction between coordinate time (measured by laboratory clocks) and chronology (temporal ordering) by defining 4D spacetime events xμ as functions of an external evolution parameter τ. Classical spacetime events xμ (τ) evolve as τ grows monotonically, tracing out particle worldlines dynamically and inducing the five U(1) gauge potentials through which events interact. Since Lorentz invariance imposes time reversal symmetry on x0 but not τ, the formalism resolves grandfather paradoxes and related problems of irreversibility. The action involves standard first order field derivatives but includes a higher order τ derivative that while preserving gauge and Lorentz invariance removes certain singularities and makes the related QFT super-renormalizable. The resulting field equations are Maxwell-like but τ-dependent and sourced by a current that represents a Statistical Ensemble of instantaneous events distributed along the worldline. The width λ of this distribution defines a correlation time for the interactions and a mass spectrum for the photons that carry the interaction. As λ becomes very large, the photon mass goes to zero and the field equations become τ-independent Maxwell’s equations. Maxwell theory thus emerges as an equilibrium limit of SHP, in which λ is larger than any other relevant time scale. Particles and fields are not constrained to mass shells in SHP theory, and by exchanging mass may produce pair creation/annihilation processes at the classical level. On-shell evolution with fixed particle masses is restored through a self-interaction associated with the 5D wave equation.
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Current as Statistical Ensemble of events in Stueckelberg-Horwitz-Piron Electrodynamics
Proceedings of 3rd International Electronic and Flipped Conference on Entropy and Its Applications, 2016Co-Authors: Martin LandAbstract:Stueckelberg-Horwitz-Piron (SHP) electrodynamics formalizes the distinction between coordinate time (measured by laboratory clocks) and chronology (temporal ordering) by defining 4D spacetime events xμ as functions of an external evolution parameter τ. The spacetime evolution of classical events xμ(τ), as τ grows monotonically, trace out particle worldlines dynamically and induce the five U(1) gauge potentials through which events interact. Since Lorentz invariance imposes time reversal symmetry on x0 but not τ, the formalism resolves grandfather paradoxes and related problems of irreversibility. Nevertheless, the causal structure of the 5D Green's function introduces singularities in the τ-dependence of the induced fields that must be treated with care for classical interactions. These singularities are regularized by generalizing the action to include a non-local kinetic term for the fields. The resulting theory remains gauge and Lorentz invariant, and the related QFT becomes super-renormalizable. The field equations are Maxwell-like but τ-dependent and sourced by a current that represents a Statistical Ensemble of events distributed along the worldline. The width of the distribution defines a mass spectrum for the photons that carry the interaction. As the width becomes very large, the photon mass goes to zero and the field equations become τ-independent Maxwell's equations. Maxwell theory thus emerges as an equilibrium limit of SHP. Particles and fields can exchange mass in the SHP theory, however on-shell particle mass is restored through self-interaction.
Filippo Castiglione - One of the best experts on this subject based on the ideXlab platform.
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Statistical Ensemble of gene regulatory networks of macrophage differentiation
BMC Bioinformatics, 2016Co-Authors: Filippo Castiglione, Paolo Tieri, Alessandro Palma, Abdul Salam JarrahAbstract:Background Macrophages cover a major role in the immune system, being the most plastic cell yielding several key immune functions. Methods Here we derived a minimalistic gene regulatory network model for the differentiation of macrophages into the two phenotypes M1 (pro-) and M2 (anti-inflammatory). Results To test the model, we simulated a large number of such networks as in a Statistical Ensemble. In other words, to enable the inter-cellular crosstalk required to obtain an immune activation in which the macrophage plays its role, the simulated networks are not taken in isolation but combined with other cellular agents, thus setting up a discrete minimalistic model of the immune system at the microscopic/intracellular (i.e., genetic regulation) and mesoscopic/intercellular scale. Conclusions We show that within the mesoscopic level description of cellular interaction and cooperation, the gene regulatory logic is coherent and contributes to the overall dynamics of the Ensembles that shows, Statistically, the expected behaviour.
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Statistical Ensemble of gene regulatory networks of macrophage differentiation.
BMC bioinformatics, 2016Co-Authors: Filippo Castiglione, Paolo Tieri, Alessandro Palma, Abdul Salam JarrahAbstract:Macrophages cover a major role in the immune system, being the most plastic cell yielding several key immune functions. Here we derived a minimalistic gene regulatory network model for the differentiation of macrophages into the two phenotypes M1 (pro-) and M2 (anti-inflammatory). To test the model, we simulated a large number of such networks as in a Statistical Ensemble. In other words, to enable the inter-cellular crosstalk required to obtain an immune activation in which the macrophage plays its role, the simulated networks are not taken in isolation but combined with other cellular agents, thus setting up a discrete minimalistic model of the immune system at the microscopic/intracellular (i.e., genetic regulation) and mesoscopic/intercellular scale. We show that within the mesoscopic level description of cellular interaction and cooperation, the gene regulatory logic is coherent and contributes to the overall dynamics of the Ensembles that shows, Statistically, the expected behaviour.
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Statistical Ensemble of gene regulatory networks of macrophage differentiation
BMC Bioinformatics, 2016Co-Authors: Filippo Castiglione, Paolo Tieri, Alessandro Palma, Abdul Salam JarrahAbstract:Background Macrophages cover a major role in the immune system, being the most plastic cell yielding several key immune functions.
