Boundary-induced instabilities in coupled oscillators

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Thermal conduction in classical low-dimensional lattices

Deriving macroscopic phenomenological laws of irreversible thermodynamics from simple microscopic models is one of the tasks of non-equilibrium statistical mechanics. We consider stationary energy transport in crystals with reference to simple mathematical models consisting of coupled oscillators on a lattice. The role of lattice dimensionality on the breakdown of the Fourier's law is discussed and some universal quantitative aspects are emphasized: the divergence of the finite-size thermal conductivity is characterized by universal laws in one and two dimensions. Equilibrium and non-equilibrium molecular dynamics methods are presented along with a critical survey of previous numerical results. Analytical results for the non-equilibrium dynamics can be obtained in the harmonic chain where the role of disorder and localization can be also understood. The traditional kinetic approach, based on the Boltzmann-Peierls equation is also briefly sketched with reference to one-dimensional chains. Simple toy models can be defined in which the conductivity is finite. Anomalous transport in integrable nonlinear systems is briefly discussed. Finally, possible future research themes are outlined.Comment: 90 pages, revised versio

Reactions to ingroup and outgroup deviants: an experimental group paradigm for Black Sheep Effect

In the classic black sheep effect (BSE) an ingroup deviant member is usually evaluated more negatively than the corresponding outgroup deviant. This effect is usually obtained by using scenarios and asking people to imagine the situation as vividly as possible. The present study proposes a new method to investigate the BSE by considering the behavioral and physiological reactions to unfair behavior (aggressive game behavior) in a realistic experimental group-setting. The study involved 52 university students in a minimal group setting who performed a modified version of the competitive reaction time (CRT) task adapted to be played in groups of four people. The classic BSE was replicated for evaluation but not for the behavioral reactions (retaliate to aggression) to deviants. More interestingly, a negative relationship emerged in the ingroup deviant condition between the level of behavioral derogation and the systolic blood pressure level

Exporting Americanism: Arthur Bullard and American Propaganda in Russia

The essay provides a broader understanding of American propaganda abroad during World War I and its aftermath by analyzing the role of the Committee on Public Information in revolutionary Russia through one of its directors, Arthur Bullard. While the main goal of the CPI was to keep Russia in the war, his view went beyond the conflict and looked at emphasizing the desire of friendly relations between the American and Russian peoples by appealing to the admiration that many Russians felt for the American lifestyle, in order to contain the spread of Bolshevism in Russian territorie

Studies of thermal conductivity in Fermi-Pasta-Ulam like lattices

The pioneering computer simulations of the energy relaxation mechanisms performed by Fermi, Pasta and Ulam can be considered as the first attempt of understanding energy relaxation and thus heat conduction in lattices of nonlinear oscillators. In this paper we describe the most recent achievements about the divergence of heat conductivity with the system size in 1d and 2d FPU-like lattices. The anomalous behavior is particularly evident at low energies, where it is enhanced by the quasi-harmonic character of the lattice dynamics. Remakably, anomalies persist also in the strongly chaotic region where long--time tails develop in the current autocorrelation function. A modal analysis of the 1d case is also presented in order to gain further insight about the role played by boundary conditions.Comment: Invited article to appear in the Chaos focus issue on "Studies of Nonlinear Problems. I" by Enrico Fermi, John Pasta, and Stanislaw Ulam

When the black sheep is not so «black». Social comparison as a standard for ingroup evaluation in classrooms

Previous research (Marques & Levine, 2016) suggests that the black sheep effect refers to the tendency of people to evaluate ingroup deviants members more negatively than outgroup deviants members. School students (N = 60) evaluated negative and positive performances attributed respectively to ingroup and outgroup members (unfavorable comparison) and negative performances attributed to both ingroup and outgroup members (neutral comparison). Results show that negative performances from ingroup members are less devaluated in the unfavorable comparisons condition than in the neutral comparisons condition and this effect is moderated by identification with their own school. Moreover, results show that in the unfavorable comparison condition students perceived a greater threat to their social identity than in the neutral comparison condition. The implications of these results are discussed in relation to the black sheep categorization and ingroup bias in a school context

Thermal physics: Heat in one dimension.

Heat is transferred along a temperature gradient, from hot to cold, at a rate determined by the thermal conductivity of the material. But is the situation so straightforward in fewer than three dimensions