Driven diffusive systems with mutually interactive Langmuir kinetics

We investigate the simple one-dimensional driven model, the totally asymmetric exclusion process, coupled to mutually interactive Langmuir kinetics. This model is motivated by recent studies on clustering of motor proteins on microtubules. In the proposed model, the attachment and detachment rates of a particle are modified depending upon the occupancy of neighbouring sites. We first obtain continuum mean-field equations and in certain limiting cases obtain analytic solutions. We show how mutual interactions increase (decrease) the effects of boundaries on the phase behavior of the model. We perform Monte Carlo simulations and demonstrate that our analytical approximations are in good agreement with the numerics over a wide range of model parameters. We present phase diagrams over a selective range of parameters.Comment: 9 pages, 8 Figure

Superadiabatic dynamical density functional study of Brownian hard-spheres in time-dependent external potentials

Superadiabatic dynamical density functional theory (superadiabatic-DDFT), a first-principles approach based on the inhomogeneous two-body correlation functions, is employed to investigate the response of interacting Brownian particles to time-dependent external driving. Predictions for the superadiabatic dynamics of the one-body density are made directly from the underlying interparticle interactions, without need for either adjustable fit parameters or simulation input. The external potentials we investigate have been chosen to probe distinct aspects of structural relaxation in dense, strongly interacting liquid states. Nonequilibrium density profiles predicted by the superadiabatic theory are compared with those obtained from both adiabatic DDFT and event-driven Brownian dynamics simulation. Our findings show that superadiabatic-DDFT accurately predicts the time-evolution of the one-body density

Mean-Field Theory of Inhomogeneous Fluids

The Barker-Henderson perturbation theory is a bedrock of liquid-state physics, providing quantitative predictions for the bulk thermodynamic properties of realistic model systems. However, this successful method has not been exploited for the study of inhomogeneous systems. We develop and implement a first-principles 'Barker-Henderson density functional', thus providing a robust and quantitatively accurate theory for classical fluids in external fields. Numerical results are presented for the hard-core Yukawa model in three dimensions. Our predictions for the density around a fixed test particle and between planar walls are in very good agreement with simulation data. The density profiles for the free liquid vapour interface show the expected oscillatory decay into the bulk liquid as the temperature is reduced towards the triple point, but with an amplitude much smaller than that predicted by the standard mean-field density functional

Lorentz forces induce inhomogeneity and flux in active systems

We consider the dynamics of a charged active Brownian particle in three dimensions subjected to an external magnetic field. We show that, in the presence of a field gradient, a macroscopic flux emerges from a flux-free system and the density distribution becomes inhomogeneous. The flux is induced by the gradient of the magnetic field only and does not require additional symmetry breaking such as density or potential gradients. This stands in marked contrast to similar phenomena in condensed matter such as the classical Hall effect. We further demonstrate that passive tracer particles can be used to measure the essential effects caused by the Lorentz force on the active particle bath, and we discuss under which conditions this diffusive Hall-like effect might be observed experimentally

Effects of Key2Teach on students' externalising and social-emotional problem behaviours, mediated by the teacher-student relationship

Teaching students with externalising problem behaviours is difficult for teachers, as it challenges the relationship that teachers engage in with their students. In this study, effects of Key2Teach on externalising and social-emotional problem behaviours and the mediating role of conflict in the teacher-student relationship were studied using a randomised controlled trial (RCT)-design. In two cohorts, 103 teacher-student dyads and peer-students (n = 1643) were assessed two times during a school year. Fifty-three dyads received the intervention (experimental group), whereas 50 dyads received no intervention (control group). Data were collected on teacher-reported externalising and social-emotional problem behaviours in students, and on teacher-student conflict. For dyad-students, results showed a direct effect of Key2Teach on conduct problems and an indirect effect, via teacher-student conflict, for hyperactivity problems. No effects on social-emotional problems were established. For peer-students, results showed indirect effects on externalising problems and direct effects on social-emotional problems. Implications for practice and future research are discussed

Effects of maternal and paternal smoking on attentional control in children with and without ADHD

Maternal smoking during pregnancy is a risk factor for attention-deficit/hyperactivity disorder (ADHD), but data on its adverse effects on cognitive functioning are sparse and inconsistent. Since the effect of maternal smoking during pregnancy may be due to correlated genetic risk factors rather than being a pure environmental effect, we examined the effect of prenatal exposure to smoking on attentional control, taking into account the effects of both maternal and paternal smoking, and examined whether these effects were genetically mediated by parental genotypes. We further examined whether the effect of prenatal exposure to smoking on attentional control interacted with genotypes of the child. Participants were 79 children with ADHD, ascertained for the International Multi-centre ADHD Gene project (IMAGE), and 105 normal controls. Attentional control was assessed by a visual continuous performance task. Three genetic risk factors for ADHD (DRD4 7-repeat allele of the exon 3 variable number of tandem repeats (VNTR), DAT1 10/10 genotype of the VNTR located in the 3′ untranslated region, and the DAT1 6/6 genotype of the intron 8 VNTR) were included in the analyses. Paternal smoking had a negative effect on attentional control in children with ADHD and this effect appeared to be mediated by genetic risk factors. The prenatal smoking effect did not interact with genotypes of the child. Maternal smoking had no main effect on attentional control, which may be due to lower smoking rates. This study suggests that the effects of paternal smoking on attentional control in children with ADHD should be considered a proxy for ADHD and/or smoking risk genes. Future studies should examine if the results can be generalized to other cognitive domains

Nondiffusive fluxes in a Brownian system with Lorentz force

The Fokker-Planck equation provides a complete statistical description of a particle undergoing random motion in a solvent. In the presence of Lorentz force due to an external magnetic field, the Fokker-Planck equation picks up a tensorial coefficient, which reflects the anisotropy of the particle's motion. This tensor, however, cannot be interpreted as a diffusion tensor; there are antisymmetric terms which give rise to fluxes perpendicular to the density gradients. Here, we show that for an inhomogeneous magnetic field these nondiffusive fluxes have finite divergence and therefore affect the density evolution of the system. Only in the special cases of a uniform magnetic field or carefully chosen initial condition with the same full rotational symmetry as the magnetic field can these fluxes be ignored in the density evolution

Direct and indirect effects of Key2Teach on teachers’ sense of self-efficacy and emotional exhaustion, a randomized controlled trial.

The effects of Key2Teach on teachers' sense of self-efficacy and emotional exhaustion related to students with externalizing problem behaviour were investigated using an RCT-design. 103 teachers were randomly assigned to an intervention or control condition and followed during a school-year. Data were collected at three time-points. Self-efficacy for instructional strategies improved at post-test and emotional exhaustion decreased at follow-up as a result of Key2Teach. Self-efficacy did not mediate the effect on emotional exhaustion. The effect of Key2Teach on self-efficacy concerning student engagement and classroom management was mediated by an increase in closeness. Implications for research and practice are discussed