Inducing pinning states and localized patterns in a monolayer of laterally attracting adatoms

The so-called "entropic mechanism" for ordering noise-induced phase transitions has been formerly used to stabilize nanopatterns in a realistic model for a monolayer of laterally interacting adsorbates. Here, we use this mechanism to stabilize pinning states and induce stochastic localized patterns ("dissipative solitons") on the monolayer. The key to achieve that goal is to displace only one of the stable homogeneous states toward field values at which the lateral interactions can elicit stable nanopatterns. At larger noise intensities, the "soliton" locations fluctuate with larger amplitude. However, since more localized patterns are elicited by the noise, their motion becomes confined when looked at longer timescales.Fil: Mangioni, Sergio Enrique. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Mar del Plata. Instituto de Investigaciones Físicas de Mar del Plata. Universidad Nacional de Mar del Plata. Facultad de Ciencias Exactas y Naturales. Instituto de Investigaciones Físicas de Mar del Plata; ArgentinaFil: Roberto R. Deza. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Mar del Plata. Instituto de Investigaciones Físicas de Mar del Plata. Universidad Nacional de Mar del Plata. Facultad de Ciencias Exactas y Naturales. Instituto de Investigaciones Físicas de Mar del Plata; Argentin

Front propagation dynamics: Qualitative differences revealed by very high intensity fluctuations

This paper presents a detailed analysis of the effect of a large external noise on the propagation of a front between two stable steady states. Noise affects one of the steady states or the thresholds. Significantdifferences with respect to the case of small noise intensity are carefully studied using a Langevin approach. The average effect of noise is modeled by means of an additional nonlinear term that enables an analysis of short-time and long-time behaviors. Nontrivial behaviors are numerically observed and analytically discussed: (i) Two symmetry breakings of the fluctuation-free stable states are observed and (ii) two fronts propagating in opposite directions are simultaneously observed and the propagation direction may be exchanged by changing the diffusion coefficient.Fil: Mangioni, Sergio Enrique. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Mar del Plata. Instituto de Investigaciones Físicas de Mar del Plata. Universidad Nacional de Mar del Plata. Facultad de Ciencias Exactas y Naturales. Instituto de Investigaciones Físicas de Mar del Plata; ArgentinaFil: Fernandez Acevedo, Javier. Universidad Nacional de Mar del Plata. Facultad de Ciencias Exactas y Naturales. Departamento de Física; Argentin

Extinction avoidance by aggregation in excitable kinetics

We considerer that a population of individuals governed by the Nagumo model is subjected to a crisis that stimulates a predisposition towards aggregation. We assume that this trend is based on the physical mechanisms of attraction between individuals. Then we describe the post-crisis dynamics and find possible states of survival (stationary solutions). We see a dynamic rich in options with several possible survival responses.Fil: Mangioni, Sergio Enrique. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Mar del Plata. Instituto de Investigaciones Físicas de Mar del Plata; Argentin

Interaction between “dissipative solitons” stabilized by aggregation in excitable kinetics

We consider that a population of individuals governed by the Nagumo model is characterized by predisposition towards aggregation. “Dissipative solitons” interacting are solutions for such system. We changed the possibility of extinction, predicted by Nagumo model, by a uniform background of low population’s density and then we observed relevant effect on interaction between “solitons”.Fil: Mangioni, Sergio Enrique. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Mar del Plata. Instituto de Investigaciones Físicas de Mar del Plata; Argentin

Systems confined by pusher multiplicative noises

We frequently employ the intuitive concept that a multiplicative noise can expel a system towards the field values for which intensity is negligible. This process applies even when such noise effects are opposed to the deterministic forces. In addition, it has been stated that a system may be confined by such noise within a field values region, distant from the stationary homogeneous solutions. In order to promote or explain noise-induced ordering phase transitions, the gradient of the multiplicative factor of noise is employed as if it were a force. However, there has not been a thorough study of this concept in the literature to date. In this paper, we conduct such a study.Fil: Mangioni, Sergio Enrique. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Mar del Plata. Instituto de Investigaciones Físicas de Mar del Plata; Argentin

A mechanism for pattern formation in dynamic populations by the effect of gregarious instinct

We introduced the gregarious instinct by means of a novel strategy that considers the average effect of the attractive forces between individuals within a given population. We watched how pattern formation can be explained by the effect of aggregation depending on conditions on food and / or mortality. We propose a model that describes the corresponding dynamic and by a linear stability analysis of homogeneous solutions and can identify and interpret the region of parameters where these patterns are stable. Then we test numerically these preliminary results and find stable patterns as solutions. Finally, we developed a simplified model allowing us to understand in greater detail the processes involved.Fil: Mangioni, Sergio Enrique. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Mar del Plata. Instituto de Investigaciones Físicas de Mar del Plata. Grupo de Investigación del Departamento de Química de la Unmdp | Universidad Nacional de Mar del Plata. Facultad de Ciencias Exactas y Naturales. Instituto de Investigaciones Físicas de Mar del Plata. Grupo de Investigación del Departamento de Química de la Unmdp; Argentin

A Cooperation between Fluctuations and Spatial Coupling for Two Symmetry-Breakings in a Gradient System

A zero-dimensional system that is affected by the field´s dependent fluctuations evolves toward field´s values in which the fluctuations´ effect is minimized. For a high enough noise intensity, it causes an exchange of roles between the stable and unstable state. In this paper, we reported symmetry-breaking in two stable states, but one of them stabilized by the fluctuations while exchanging its role with a previously stable state.Fil: Mangioni, Sergio Enrique. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Mar del Plata. Instituto de Investigaciones Físicas de Mar del Plata; Argentin

Generalized Nagumo Model: Interesting Effects of Parameters's Fluctuations

In this paper, we used an analytical method to calculate the effects that produce the parameter’s fluctuations characterizing a generalization of Nagumo model. (The extinction option is replaced by one of low density homogeneous population.) Moreover, we also check the results by means of numerical simulations of the corresponding stochastic process. We find that these fluctuations have a strong impact on the solutions producing interesting changes.Fil: Mangioni, Sergio Enrique. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Mar del Plata. Instituto de Investigaciones Físicas de Mar del Plata; Argentin

Stochastic dissipative solitons

By the effect of aggregating currents, some systems display an effective diffusion coefficient that becomesnegative in a range of the order parameter, giving rise to bistability among homogeneous states (HSs). By applyinga proper multiplicative noise, localized (pinning) states are shown to become stable at the expense of one ofthe HSs. They are, however, not static, but their location fluctuates with a variance that increases with the noiseintensity. The numerical results are supported by an analytical estimate in the spirit of the so-called solvabilitycondition.Fil: Mangioni, Sergio Enrique. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Mar del Plata. Instituto de Investigaciones Físicas de Mar del Plata; ArgentinaFil: Deza, R. R.. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Mar del Plata. Instituto de Investigaciones Físicas de Mar del Plata; Argentin

Limiting the stroke of a Schmitt trigger with multiplicative noise

We have devised an experiment whereby a bistable system is confined away from its deterministic attractors by means of multiplicative noise. Together with previous numerical results, our experimental results validate the hypothesis that the higher the slope of the noise?s multiplicative factor, the more it shifts the stationary states.Fil: Zarza, Gabriel Alejandro. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Mar del Plata. Instituto de Investigaciones Físicas de Mar del Plata. Universidad Nacional de Mar del Plata. Facultad de Ciencias Exactas y Naturales. Instituto de Investigaciones Físicas de Mar del Plata; ArgentinaFil: Mangioni, Sergio Enrique. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Mar del Plata. Instituto de Investigaciones Físicas de Mar del Plata. Universidad Nacional de Mar del Plata. Facultad de Ciencias Exactas y Naturales. Instituto de Investigaciones Físicas de Mar del Plata; ArgentinaFil: Fernandez Acevedo, Javier. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Mar del Plata. Instituto de Investigaciones Físicas de Mar del Plata. Universidad Nacional de Mar del Plata. Facultad de Ciencias Exactas y Naturales. Instituto de Investigaciones Físicas de Mar del Plata; ArgentinaFil: Deza, Roberto Raul. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Mar del Plata. Instituto de Investigaciones Físicas de Mar del Plata. Universidad Nacional de Mar del Plata. Facultad de Ciencias Exactas y Naturales. Instituto de Investigaciones Físicas de Mar del Plata; Argentin