Head movement differs for positive and negative emotions in video recordings of sitting individuals

Individuals tend to approach positive stimuli and avoid negative stimuli. Furthermore, emotions influence whether individuals freeze or move more. These two kinds of motivated behavior refer to the approach/avoidance behavior and behavioral freezing/activation. Previous studies examined (e.g., using forced platforms) whether individuals' behavior depends on stimulus' valence; however, the results were mixed. Thus, we aimed to test whether emotions' effects on spontaneous whole-body behavior of standing individuals also occur in the seated position. We used a computer vision method to measure the head sway in video recordings that offers ease of use, replicability, and unobtrusiveness for the seated research participant. We analyzed behavior recorded in the laboratory during emotion manipulations across five studies totaling 932 participants. We observed that individuals leaned more forward and moved more when watching positive stimuli than when watching negative stimuli. However, individuals did not behave differently when watching positive or negative stimuli than in the neutral condition. Our results indicate that head movements extracted from seated individuals' video recordings can be useful in detecting robust differences in emotional behavior (positive vs. negative emotions)

Control of serpentinisation rate by reaction-induced cracking

Serpentinisation of mantle rocks requires the generation and maintenance of transport pathways for water. The solid volume increase during serpentinisation can lead to stress build-up and trigger cracking, which ease fluid penetration into the rock. The quantitative effect of this reaction-induced cracking mechanism on reactive surface generation is poorly constrained, thus hampering our ability to predict serpentinisation rate in geological environments. Here we use a combined approach with numerical modelling and observations in natural samples to provide estimates of serpentinisation rate at mid-ocean ridges. We develop a micromechanical model to quantify the propagation of serpentinisation-induced cracks in olivine. The maximum crystallisation pressure deduced from thermodynamic calculations reaches several hundreds of megapascals but does not necessary lead to crack propagation if the olivine grain is subjected to high compressive stresses. The micromechanical model is then coupled to a simple geometrical model to predict reactive surface area formation during grain splitting, and thus bulk reaction rate. Our model reproduces quantitatively experimental kinetic data and the typical mesh texture formed during serpentinisation. We also compare the model results with olivine grain size distribution data obtained on natural serpentinised peridotites from the Marum ophiolite and the Papuan ultramafic belt (Papua New Guinea). The natural serpentinised peridotites show an increase of the number of olivine grains for a decrease of the mean grain size by one order of magnitude as reaction progresses from 5 to 40%. These results are in agreement with our model predictions, suggesting that reaction-induced cracking controls the serpentinisation rate. We use our model to estimate that, at mid-ocean ridges, serpentinisation occurs up to 12km depth and reaction-induced cracking reduces the characteristic time of serpentinisation by one order of magnitude, down to values comprised between 10 and 1000yr. The increase of effective pressure with depth also prevents cracking, which positions the peak in serpentinisation rate at shallower depths, 4km above previous predictions

Static QˉQ\bar Q Q Potentials and the Magnetic Component of QCD Plasma near TcT_c

Static quark-anti-quark potential encodes important information on the chromodynamical interaction between color charges, and recent lattice results show its very nontrivial behavior near the deconfinement temperature $T_c$. In this paper we study such potential in the framework of the ``magnetic scenario'' for the near Tc QCD plasma, and particularly focus on the linear part (as quantified by its slope, the tension) in the potential as well as the strong splitting between the free energy and internal energy. By using an analytic ``ellipsoidal bag'' model, we will quantitatively relate the free energy tension to the magnetic condensate density and relate the internal energy tension to the thermal monopole density. By converting the lattice results for static potential into density for thermal monopoles we find the density to be very large around Tc and indicate at quantum coherence, in good agreement with direct lattice calculation of such density. A few important consequences for heavy ion collisions phenomenology will also be discussed.Comment: 10 pages, 6 figure

Magnetic component of Yang-Mills plasma

Confinement in non-Abelian gauge theories is commonly ascribed to percolation of magnetic monopoles, or strings in the vacuum. At the deconfinement phase transition the condensed magnetic degrees of freedom are released into gluon plasma as thermal magnetic monopoles. We point out that within the percolation picture lattice simulations can be used to estimate the monopole content of the gluon plasma. We show that right above the critical temperature the monopole density remains a constant function of temperature, as for a liquid, and then grows, like for a gas.Comment: 4 pages, no figures; replaced to match published versio

Magnetoelectricity at room temperature in Bi0.9-xTbxLa0.1FeO3 system

Magnetoelectric compounds with the general formula, Bi0.9-xRxLa0.1FeO3 (R =Gd, Tb, Dy, etc.), have been synthesized. These show the coexistence of ferroelectricity and magnetism, possess high dielectric constant and exhibit magnetoelectric coupling at room temperature. Such materials may be of great significance in basic as well as applied research.Comment: 11 pages of text and figure

Experimental demonstration of quantum effects in the operation of microscopic heat engines

The heat engine, a machine that extracts useful work from thermal sources, is one of the basic theoretical constructs and fundamental applications of classical thermodynamics. The classical description of a heat engine does not include coherence in its microscopic degrees of freedom. By contrast, a quantum heat engine might possess coherence between its internal states. Although the Carnot efficiency cannot be surpassed, and coherence can be performance degrading in certain conditions, it was recently predicted that even when using only thermal resources, internal coherence can enable a quantum heat engine to produce more power than any classical heat engine using the same resources. Such a power boost therefore constitutes a quantum thermodynamic signature. It has also been shown that the presence of coherence results in the thermodynamic equivalence of different quantum heat engine types, an effect with no classical counterpart. Microscopic heat machines have been recently implemented with trapped ions, and proposals for heat machines using superconducting circuits and optomechanics have been made. When operated with standard thermal baths, however, the machines implemented so far have not demonstrated any inherently quantum feature in their thermodynamic quantities. Here we implement two types of quantum heat engines by use of an ensemble of nitrogen-vacancy centres in diamond, and experimentally demonstrate both the coherence power boost and the equivalence of different heat-engine types. This constitutes the first observation of quantum thermodynamic signatures in heat machines

Anharmonicity of BaTiO_3 single crystals

By analyzing the dielectric non-linearity with the Landau thermodynamic expansion, we find a simple and direct way to assess the importance of the eighth order term. Following this approach, it is demonstrated that the eighth order term is essential for the adequate description of the para/ferroelectric phase transition of BaTiO_3. The temperature dependence of the quartic coefficient \beta is accordingly reconsidered and is strongly evidenced by the change of its sign above 165 C. All these findings attest to the strong polarization anharmonicity of this material, which is unexpected for classical displacive ferroelectrics.Comment: 4 figures, to be published in Phys. Rev.

Effects of mesonic correlations in the QCD phase transition

The finite temperature phase transition of strongly interacting matter is studied within a nonlocal chiral quark model of the NJL type coupled to a Polyakov loop. In contrast to previous investigations which were restricted to the mean-field approximation, mesonic correlations are included by evaluating the quark-antiquark ring sum. For physical pion masses, we find that the pions dominate the pressure below the phase transition, whereas above T_c the pressure is well described by the mean-field approximation result. For large pion masses, as realized in lattice simulations, the meson effects are suppressed.Comment: 11 pages, 4 figures; version accepted for publication in Yad. Fiz., text extended, 1 figure adde

Gluon Quasiparticles and the Polyakov Loop

A synthesis of Polyakov loop models of the deconfinement transition and quasiparticle models of gluon plasma thermodynamics leads to a class of models in which gluon quasiparticles move in a non-trivial Polyakov loop background. These models are successful candidates for explaining both critical behavior and the equation of state for the SU(3) gauge theory at temperatures above the deconfinement temperature T_c. Polyakov loops effects are most important at intermediate temperatures from T_c up to roughly 2.5 T_c, while quasiparticle mass effects provide the dominant correction to blackbody behavior at higher temperatures.Comment: 6 pages, 7 eps figures, revtex