Some marine bacterial species form mucosal layers, called veils, on sulfidic marine sediment. The bacteria attached to this veil actively swim and exert force on the surrounding fluid. The bacteria can break free of the veil and swim, chemotacting back to the veil. Over time the veil forms holes arranged in a hexagonal pattern. Motivated by this system, we present a simplified model to describe...

We describe a novel mechanism that mediates the rapid and selective pattern formation of neuronal network activity in response to changing correlations of sub-threshold level input. The mechanism is based on the classical resonance and experimentally observed phenomena that the resonance frequency of a neuron shifts as a function of membrane depolarization. As the neurons receive varying sub-th...

The Mathieu partial differential equation (PDE) is analyzed as a prototypical model for pattern formation due to parametric resonance. After averaging and scaling, it is shown to be a perturbed nonlinear Schrödinger equation (NLS). Adiabatic perturbation theory for solitons is applied to determine which solitons of the NLS survive the perturbation due to damping and parametric forcing. Numerica...

ADIFFERENCE has been observed in certain instances between the onset of QRS in intracavitary and surface limb leads. Simultaneous tracings demonstrate that when premature ventricular depolarization exists the early rapid growth in magnitude of potential recorded by intracavitary leads may be nearly or totally inapparent in surface leads. Following premature depolarization changes occur in intra...

This study investigates how ambivalence over emotional expressiveness (AEE) relates to various aspects of intimate relationships, including perception of the relationship, marital satisfaction, and dyadic closeness. Whereas most commonly AEE has been treated as an individual attribute, we suggest looking at a combined measure of the AEE of both spouses as a dyadic attribute. We examine the cont...

A weakly nonlinear multiple-scales analysis is performed for singly resonant second-harmonic generation. Coupled amplitude equations are derived that describe pattern formation above the transverse instability threshold. The amplitude equations explain the absence of roll patterns and are in good agreement with numerical results. Ó 2000 Elsevier Science B.V. All rights reserved. PACS: 42.65.Sf;...

We extend the mechanism for noise-induced phase transitions proposed by Ibañes et al. [Phys. Rev. Lett. 87, 020601-1 (2001)] to pattern formation phenomena. In contrast with known mechanisms for pure noise-induced pattern formation, this mechanism is not driven by a short-time instability amplified by collective effects. The phenomenon is analyzed by means of a modulated mean field approximatio...

This pilot study of 23 mothers with attention-deficit/hyperactivity disorder (ADHD) and their offspring with ADHD examined the effects of maternal stimulant medication on observed interactions. Parent-child interactions were observed using a structured protocol before and after mothers underwent a 5-week, double-blind stimulant titration. Despite dramatic effects of medication on adult ADHD sym...