1,720,983 research outputs found
On a Statistical Mechanics Approach to Some Problems of the Social Sciences
Full text linkThis work is a survey of some results on a statistical mechanics approach to the social sciences emerged in the last two decades. The pioneering work of Daniel McFadden, known as discrete choice theory, is interpreted in terms of a non-interacting model and extended along the lines of the Brock and Durlauf interacting systems. The generalization to the multi-populated model is presented and two specific case studies are reviewed with their phenomenological and theoretical analysis
O(N) Fluctuations and Lattice Distortions in 1-Dimensional Systems
Full text linkStatistical mechanics harmonizes mechanical and thermodynamical quantities, via the notion of local thermodynamic equilibrium (LTE). In absence of external drivings, LTE becomes equilibrium tout court, and states are characterized by several thermodynamic quantities, each of which is associated with negligibly fluctuating microscopic properties. Under small driving and LTE, locally conserved quantities are transported as prescribed by linear hydrodynamic laws, in which the local material properties of the system are represented by the transport coefficients. In 1-dimensional systems, on the other hand, various anomalies are reported, such as the dependence of the heat conductivity on the global state, rather than on the local state. Such deductions, that rely on the existence of thermodynamic quantities like temperature and heat, are here interpreted within the framework of boundary driven 1-dimensional Lennard-Jones chains of N oscillators. It is found that these chains experience non-negligible O(N) lattice distortions, resulting in strongly inhomogeneous systems, and O(N) position fluctuations, that are in contrast with the requirements of LTE
Exploring mortality representation and the impact of COVID-19 in Modena: insights from “An ECG-based machine-learning approach for mortality risk assessment in a large European population”
No full textFinite-size corrections for the attractive mean-field monomer-dimer model
No full textThe finite volume correction for a mean-field monomer-dimer system with an attractive interaction are computed for the pressure density, the monomer density and the susceptibility. The results are obtained by introducing a two-dimensional integral representation for the partition function decoupling both the hard-core interaction and the attractive one. The next-to-leading terms for each of the mentioned quantities are explicitly derived as well as the value of their sign that is related to their monotonic convergence in the thermodynamic limit
On quasiperiodic travelling waves in coupled map lattices
No full textWe investigate quasiperiodic travelling waves (QTWs) in lattices of diffusively coupled logistic maps. Starting from the assumption that any spatial structure can be broken down into simpler elementary structures, a classification scheme for QTWs is introduced. Within this framework. the phenomenon of discrete velocities is reviewed and further investigated. In addition, a new technique is proposed for predicting whether QTWs can occur for given parameter values and which they might be
Asymmetric fluctuation-relaxation paths in FPU models
No full textA recent theory by Bertini, De Sole, Gabrielli, Jona-Lasinio and Landim predicts a temporal asymmetry in thefluctuation–relaxation paths of certain observables of nonequilibrium systems in local thermodynamic equilibrium. Wefind temporal asymmetries in the fluctuation–relaxation paths of a form of local heat flow, in the nonequilibrium FPU-bmodel of Lepri, Livi and Politi
Uphill diffusions in single and multi-species systems
No full textUphill diffusions constitute an intriguing phenomenon reported in a series of numerical simulations and experiments in which particles move from lower to higher density regions, at variance with the basic tenets of transport theory. In this paper we review several examples of uphill diffusions that appear in quite different frameworks. We highlight the role of the coupling with external reservoirs in the onset of particle currents with the 'wrong' sign, and also put forward a statistical mechanical explanation of the phenomenon for stochastic multi-species systems as well as for single-species models undergoing a phase transition
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