Wave-unlocking transition in resonantly coupled complex Ginzburg-Landau equations

We study the effect of spatial frequency-forcing on standing-wave solutions of coupled complex Ginzburg-Landau equations. The model considered describes several situations of nonlinear counterpropagating waves and also of the dynamics of polarized light waves. We show that forcing introduces spatial modulations on standing waves which remain frequency locked with a forcing-independent frequency. For forcing above a threshold the modulated standing waves unlock, bifurcating into a temporally periodic state. Below the threshold the system presents a kind of excitability.Comment: 4 pages, including 4 postscript figures. To appear in Physical Review Letters (1996). This paper and related material can be found at http://formentor.uib.es/Nonlinear

Synchronization of Spatiotemporal Chaos: The regime of coupled Spatiotemporal Intermittency

Synchronization of spatiotemporally chaotic extended systems is considered in the context of coupled one-dimensional Complex Ginzburg-Landau equations (CGLE). A regime of coupled spatiotemporal intermittency (STI) is identified and described in terms of the space-time synchronized chaotic motion of localized structures. A quantitative measure of synchronization as a function of coupling parameter is given through distribution functions and information measures. The coupled STI regime is shown to dissapear into regular dynamics for situations of strong coupling, hence a description in terms of a single CGLE is not appropiate.Comment: 4 pages, LaTeX 2e. Includes 3 figures made up of 8, 4 (LARGE),and 2 postscript files. Includes balanced.st

Neighborhood models of minority opinion spreading

We study the effect of finite size population in Galam's model [Eur. Phys. J. B 25 (2002) 403] of minority opinion spreading and introduce neighborhood models that account for local spatial effects. For systems of different sizes N, the time to reach consensus is shown to scale as ln N in the original version, while the evolution is much slower in the new neighborhood models. The threshold value of the initial concentration of minority supporters for the defeat of the initial majority, which is independent of N in Galam's model, goes to zero with growing system size in the neighborhood models. This is a consequence of the existence of a critical size for the growth of a local domain of minority supporters

Buyer Engagement and Labour Conditions in Global Supply Chains:The Bangladesh Accord and Beyond

The Accord on Fire and Building Safety in Bangladesh (‘the Accord’) has received both praise and criticism concerning its implications for corporate responsibility and power. This article contributes to the debate by situating the Accord within a broader set of activities that buyers are engaged in to promote better labour conditions in their supply chains. The authors identify three approaches of buyer engagement: auditing, capacity building and advocacy. Drawing on interviews conducted with European brands and retailers, the article shows how buyers perceive the merits and challenges of these approaches, and whether and how they discharge responsibility and power through these activities. The study shows that the Accord is seen primarily as part of the auditing approach with a key feature being its use of collective leverage as a means of enforcement. While greater buyer power has not necessarily been accompanied by greater responsibility, the article highlights heterogeneity among buyers in how they take up different approaches, painting a more nuanced picture of buyer responsibility and power

Efecto de la aplicación de herbicidas sobre la calidad comercial e industrial de trigo pan

Se trató de verificar la incidencia de los herbicidas Bromoxinil, 2.4-D más Piclorán y 2,4-D más Dicamba a dosis normal y doble aplicadas en cinco épocas (entre cinco hojas y aristas asomando~ sobre la calidad comercial e industrial de trigo de ciclo largo Cv. Chasicó INTA. No se encontraron diferencias en peso de mil granos (PMG) Y peso hectolítrico (PH) en ningún caso. El porcentaje de extracción de harina (EP) mostró diferencias significativas debido a la época. El tenor de proteína cruda de la harina fue modificado por el tipo de herbicida más que por la dosis, la época de aplicación no produjo efecto significativo. El trabajo de deformación (W) fue afectado significativamente por la dosis, no así por el tipo de herbicida y época de aplicación. El índice de estabilidad (P/G) presentó diferencias significativas debido a los tres factores (tipo, dosis y época). Se detectó interacción dosis por época para éste parámetro. Comparados con el desmalezado manual Bromoxinil se produjo efectos significativos sobre la cantidad y calidad de la proteína de la harina, mientras que los mayores efectos fueron producidos por 2,4-D más Dicamba. Las variaciones de rendimiento explican en parte las diferencias en el contenido de proteínas.Directores: Ings. Agrs. F. D. García y O. J. Rubiol

Multiple Front Propagation Into Unstable States

The dynamics of transient patterns formed by front propagation in extended nonequilibrium systems is considered. Under certain circumstances, the state left behind a front propagating into an unstable homogeneous state can be an unstable periodic pattern. It is found by a numerical solution of a model of the Fr\'eedericksz transition in nematic liquid crystals that the mechanism of decay of such periodic unstable states is the propagation of a second front which replaces the unstable pattern by a another unstable periodic state with larger wavelength. The speed of this second front and the periodicity of the new state are analytically calculated with a generalization of the marginal stability formalism suited to the study of front propagation into periodic unstable states. PACS: 47.20.Ky, 03.40.Kf, 47.54.+rComment: 12 page