On the prevalence of non-Gibbsian states in mathematical physics

Gibbs measures are the main object of study in equilibrium statistical mechanics, and are used in many other contexts, including dynamical systems and ergodic theory, and spatial statistics. However, in a large number of natural instances one encounters measures that are not of Gibbsian form. We present here a number of examples of such non-Gibbsian measures, and discuss some of the underlying mathematical and physical issues to which they gave rise

Feel good, do-good!? On consistency and compensation in moral self-regulation

Studies in the behavioral ethics and moral psychology traditions have begun to reveal the important roles of self-related processes that underlie moral behavior. Unfortunately, this research has resulted in two distinct and opposing streams of findings that are usually referred to as moral consistency and moral compensation. Moral consistency research shows that a salient self-concept as a moral person promotes moral behavior. Conversely, moral compensation research reveals that a salient self-concept as an immoral person promotes moral behavior. The present study’s aim was to integrate these two literatures. We argued that compensation forms a reactive, “damage control” response in social situations, whereas consistency derives from a more proactive approach to reputation building and maintenance. Two experiments supported this prediction in showing that cognitive depletion (i.e., resulting in a reactive approach) results in moral compensation whereas consistency results when cognitive resources are available (i.e., resulting in a proactive approach). Experiment 2 revealed that these processes originate from reputational (rather than moral) considerations by showing that they emerge only under conditions of accountability. It can thus be concluded that reputational concerns are important for both moral compensation and moral consistency processes, and that which of these two prevails depends on the perspective that people take: a reactive or a proactive approach

Being “in Control” May Make You Lose Control: The Role of Self-Regulation in Unethical Leadership Behavior

In the present article, we argue that the constant pressure that leaders face may limit the willpower required to behave according to ethical norms and standards and may therefore lead to unethical behavior. Drawing upon the ego depletion and moral self-regulation literatures, we examined whether self-regulatory depletion that is contingent upon the moral identity of leaders may promote unethical leadership behavior. A laboratory experiment and a multisource field study revealed that regulatory resource depletion promotes unethical leader behaviors among leaders who are low in moral identity. No such effect was found among leaders with a high moral identity. This study extends our knowledge on why organizational leaders do not always conform to organizational goals. Specifically, we argue that the hectic and fragmented workdays of leaders may increase the likelihood that they violate ethical norms. This highlights the necessity to carefully schedule tasks that may have ethical implications. Similarly, organizations should be aware that overloading their managers with work may increase the likelihood of their leaders transgressing ethical norms

Out of Control!? How Loss of Self-Control Influences Prosocial Behavior: The Role of Power and Moral Values

Lack of self-control has been suggested to facilitate norm-transgressing behaviors because of the operation of automatic selfish impulses. Previous research, however, has shown that people having a high moral identity may not show such selfish impulses when their self-control resources are depleted. In the present research, we extended this effect to prosocial behavior. Moreover, we investigated the role of power in the interaction between moral identity and self-control depletion. More specifically, we expected that power facilitates the externalization of internal states, which implies that for people who feel powerful, rather than powerless, depletion decreases prosocial behavior especially for those low in moral identity. A laboratory experiment and a multisource field study supported our predictions. The present finding that the interaction between self-control depletion and moral identity is contingent upon people’s level of power suggests that power may enable people to refrain from helping behavior. Moreover, the findings suggest that if organizations want to improve prosocial behaviors, it may be effective to situationally induce moral values in their employees

On the Variational Principle for Generalized Gibbs Measures

We present a novel approach to establishing the variational principle for Gibbs and generalized (weak and almost) Gibbs states. Limitations of a thermodynamical formalism for generalized Gibbs states will be discussed. A new class of intuitively weak Gibbs measures is introduced, and a typical example is studied. Finally, we present a new example of a non-Gibbsian measure arising from an industrial application.Comment: To appear in Markov Processes and Related Fields, Proceedings workshop Gibbs-nonGibb

Stokes parameters for light scattering from a Faraday-active sphere

We present an exact calculation for the scattering of light from a single sphere made of Faraday-active material, to first order in the external magnetic field. We use a recent expression for the T-matrix of a Mie scatterer in a magnetic field to compute the Stokes parameters in single scattering that describe completely flux and polarization of the scattered light.Comment: 17 pages, 5 figures, Latex, accepted for publication in JQSR

Role of mean free path in spatial phase correlation and nodal screening

We study the spatial correlation function of the phase and its derivative, and related, fluctuations of topological charge, in two and three dimensional random media described by Gaussian statistics. We investigate their dependence on the scattering mean free path.Comment: 7 pages, 6 figures. submitted to Europhys. Let

Interaction of Ising-Bloch fronts with Dirichlet Boundaries

We study the Ising-Bloch bifurcation in two systems, the Complex Ginzburg Landau equation (CGLE) and a FitzHugh Nagumo (FN) model in the presence of spatial inhomogeneity introduced by Dirichlet boundary conditions. It is seen that the interaction of fronts with boundaries is similar in both systems, establishing the generality of the Ising-Bloch bifurcation. We derive reduced dynamical equations for the FN model that explain front dynamics close to the boundary. We find that front dynamics in a highly non-adiabatic (slow front) limit is controlled by fixed points of the reduced dynamical equations, that occur close to the boundary.Comment: 10 pages, 8 figures, submitted to Phys. Rev.

Discrete approximations to vector spin models

We strengthen a result of two of us on the existence of effective interactions for discretised continuous-spin models. We also point out that such an interaction cannot exist at very low temperatures. Moreover, we compare two ways of discretising continuous-spin models, and show that, except for very low temperatures, they behave similarly in two dimensions. We also discuss some possibilities in higher dimensions.Comment: 12 page

Comparison of different objective functions for parameterization of simple respiration models

The eddy covariance measurements of carbon dioxide fluxes collected around the world offer a rich source for detailed data analysis. Simple, aggregated models are attractive tools for gap filling, budget calculation, and upscaling in space and time. Key in the application of these models is their parameterization and a robust estimate of the uncertainty and reliability of their predictions. In this study we compared the use of ordinary least squares (OLS) and weighted absolute deviations (WAD, which is the objective function yielding maximum likelihood parameter estimates with a double exponential error distribution) as objective functions within the annual parameterization of two respiration models: the Q10 model and the Lloyd and Taylor model. We introduce a new parameterization method based on two nonparametric tests in which model deviation (Wilcoxon test) and residual trend analyses (Spearman test) are combined. A data set of 9 years of flux measurements was used for this study. The analysis showed that the choice of the objective function is crucial, resulting in differences in the estimated annual respiration budget of up to 40%. The objective function should be tested thoroughly to determine whether it is appropriate for the application for which the model will be used. If simple models are used to estimate a respiration budget, a trend test is essential to achieve unbiased estimates over the year. The analyses also showed that the parameters of the Lloyd and Taylor model are highly correlated and difficult to determine precisely, thereby limiting the physiological interpretability of the parameter