Dynamics of a Ø4 kink in the presence of strong potential fluctuations, dissipation, and boundaries

We have carried out a number of simulations to study the dynamical behavior of kinks in the ifJ4 model in the presence of strong fluctuations of its double-well potential. Our work widens the computational and analytical knowledge of this system in four directions. First, we describe in detail a numerical procedure that can be easily generalized to other stochastic, soliton-bearing equations. We demonstrate that it exhibits consistency features never found in previous research on nonlinear stochastic partial differential equations. Second, we fix the range of validity of theoretical approaches based on secular perturbative expansions. We show how this range depends on a combination of noise strength and duration. Third, we numerically study the model beyond the applicability of analytical methods. We compute the main characteristics of kink dynamics in this regime and discuss their stability under this random perturbation. Finally, we introduce dissipation and boundaries in the dynamically disordered model. We establish that the essential consequence of friction action is to soften the noise effects, while boundaries give rise to a critical velocity below which kinks cannot enter the noisy zone.We are thankful for partial financial support from the Direccion General de Investigacion Cientifica y Tecnica (DGICyT) through Project No. TIC 73/89. A.S. was supported by the program ((Formacion de Personal Investigador" of the Ministerio de Educación y Ciencia of Spain.Publicad

Editorial

Editoria

Editorial

[EN] This special issue is the result of the joint work developed between the International Association on Public and nonProfit Marketing and the Journal of business of the Universidad del Pacífico, in favor of the dissemination of the most avant-garde scientific knowledge on topics of special social relevance for Latin America. The IAPNM, as a reference association in its field, has been developing since 2002 an arduous effort to connect academics and practitioners from marketing or other related disciplines dealing with responsibility in businesses, administrations and nonprofits; these topics of special interest to the journal.S

Radiological protection in the Spanish nuclear industry under Franco, 1939-1975

Este trabajo es una reelaboración del capítulo de la memoria de doctorado de Sánchez Vázquez, 2010, p.189-215, dedicado a la protección radiológica.En los debates sobre la controversia nuclear pocas veces se presenta en primera plana la cuestión de la seguridad laboral en las instalaciones radiactivas. Históricamente se ha priorizado la atención a los potenciales daños a la población general frente a la propia seguridad de los trabajadores empleados en instalaciones de riesgo. Con objeto de cubrir parcialmente ese vacío historiográfico, este trabajo pretende llevar a cabo un acercamiento al desarrollo de la protección radiológica laboral en España durante la dictadura del general Franco (1939-1975). Para ello repasaremos el surgimiento de las medidas de protección radiológica en el ámbito internacional y el posterior desarrollo legislativo en el caso español, proceso que fue paralelo al crecimiento del programa nuclear nacional. Para finalizar, exploraremos las principales evidencias del impacto de las radiaciones ionizantes sobre la población laboral españolaIn debates about nuclear controversy, the issue of occupational safety in radioactive facilities is rarely foregrounded; it has historically been relegated to second place compared to the attention given to potential harm to the general population. Aiming for, al least, partially filling this historiographical gap, this article deals with the development of occupational radiological protection in Spain under the dictatorship of General Franco (1939-1975). It covers the rise of radiological protection measures on an international level and the subsequent development of legislation in the case of Spain, a process that paralleled the growth of the nation’s nuclear program. Finally, it explores the main evidence of the impact of ionizing radiation on Spain’s working population

Kink decay in a parametrically driven Ø4 chain

We consider the parametrically driven discrete Ø4 model with loss. Using an analytical approach and direct numerical simulations, which turn out to be in excellent agreement, we demonstrate that there is a range of driving parameters such that kinks cannot exist in the system. This effed may be understood with the help of an averaged external potential energy of the system, which has no double-well structure in this region.This work has been supported in part by the Comisi6n Interministerial de Ciencia y Tecnologia (CICyT) of Spain, through Project No. MAT90-0544.Publicad

Resistance Science? Participatory environmental monitoring in contexts of environmental conflict. Reflections from a decolonial view

La producción de conocimiento tecno-científico sobre los impactos y transformaciones ambientales que generan los mega-proyectos mineros, es un elemento clave en manejo de los conflictos socioambientales producidos por el extractivismo. Generalmente, los informes oficiales son controlados por el Estado y por la empresa concesionaria, con lo que la producción de conocimiento técnico y científico lleva un marcado sesgo de apoyo y legitimación al proyecto. Aunque existen procesos participativos vinculados a estos procedimientos, las comunidades locales afectadas tienen un margen muy limitado de incidencia real en la toma de decisiones y en las definiciones de la realidad ambiental afectada. Ante esta situación, surgen diferentes vías para contrarrestar la producción de conocimiento científico oficial y hegemónica. En el presente trabajo describo distintas iniciativas de monitoreos ambientales independientes y producción científica alternativa, desarrolladas por la población local afectada por el primer proyecto mega-minero en Ecuador: el Proyecto Mirador. A través de ese caso, analizo hasta qué punto este tipo de procesos pueden suponer una vía de resistencia contra-hegemónica activa, que la misma comunidad ha denominado “ciencia de resistencia”, en un contexto de conflicto e injusticia ambiental. Combinando los enfoques interdisciplinares de la ecología política y los estudios de paz y conflictos con la perspectiva decolonial, el estudio de este caso revela dilemas y dificultades de los procesos de resistencia, pero también posibilidades de generar vías alternativas de construcción de conocimiento científico y transformación del conflicto.Production of techno-scientific knowledge about the environmental impacts of a large-scale mining project is a central element in order to analyse the environmental conflicts generated by the extractive activities. The official reports are controlled and supervised by the State and the mining companies, thus the production of scientific knowledge about the project is essentially designed to support and legitimize the extraction. Although there are some participatory mechanisms linked to these formal procedures, local communities affected by extractive activities can barely influence the decision making process. Therefore, anti-mining movements seek for different alternative options to counteract the official scientific knowledge production. In this paper, I describe different processes of environmental participatory monitoring, where local population affected by the Mirador Project in Ecuador collaborate with NGO and independent research centres. I analyse to what extent this kind of process can actually be a form of “counterwork” and active resistance to the mining project, a “science of resistance” in the words of the anti-mining movement. Combining the interdisciplinary approaches of political ecology and peace and conflicts studies with the decolonial perspective, the analysis of this case reveals dilemmas and difficulties of resistance processes, but also possibilities of generating alternative ways of building scientific knowledge and transformation of the conflict

VLSI implementation of a transconductance mode continuous BAM with on chip learning and dynamic analog memory

In this paper we present a complete VLSI Continuous-Time Bidirectional Associative Memory (BAM). The short term memory (STM) section is implemented using small transconductance four quadrant multipliers, and capacitors for the integrators. The long term memory (LTM) is built using an additional multiplier that uses locally available signals to perform Hebbian learning. The value of the learned weight is present at a capacitor for each synapse. After learning has been accomplished the value of the stored weight voltage can be refreshed using a simple AID-D/A conversion, which if done fast enough, will maintain the weight value within a discrete interval of the complete weight range. Such a discretization still allows good performance of the STM section after learning is finished

Analog integrated neural-like circuits for nonlinear programming

A systematic approach for the design of analog neural nonlinear programming solvers using switched-capacitor (SC) integrated circuit techniques is presented. The method is based on formulating a dynamic gradient system whose state evolves in time towards the solution point of the corresponding programming problem. A neuron cell for the linear and the quadratic problem suitable for monolithic implementation is introduced. The design of this neuron and its corresponding synapses using SC techniques is considered in detail. An SC circuit architecture based on a reduced set of basic building blocks with high modularity is presented. Simulation results using a mixed-mode simulator (DIANA) and experimental results from breadboard prototypes are included, illustrating the validity of the proposed technique