A Spatially Extended Model for Residential Segregation

In this paper we analyze urban spatial segregation phenomenon in terms of the income distribution over a population, and inflationary parameter weighting the evolution of housing prices. For this, we develop a discrete, spatially extended model based in a multi--agent approach. In our model, the mobility of socioeconomic agents is driven only by the housing prices. Agents exchange location in order to fit their status to the cost of their housing. On the other hand, the price of a particular house changes depends on the status of its tenant, and on the neighborhood mean lodging cost, weighted by a control parameter. The agent's dynamics converges to a spatially organized configuration, whose regularity we measured by using an entropy--like indicator. With this simple model we found a nontrivial dependence of segregation on both, the initial inequality of the socioeconomic agents and the inflationary parameter. In this way we supply an explanatory model for the segregation--inequality thesis putted forward by Douglas Massey.Comment: 17 pages, 11 figures. email: [email protected], [email protected]

Spatial chaos of traveling waves has a given velocity

International audienceWe study the complexity of stable waves in unidirectional bistable coupled map lattices as a test tube to spatial chaos of traveling patterns in open flows. Numerical calculations reveal that, grouping patterns into sets according to their velocity, at most one set of waves has positive topological entropy for fixed parameters. By using symbolic dynamics and shadowing, we analytically determine velocity-dependent parameter domains of existence of pattern families with positive entropy. These arguments provide a method to exhibit chaotic sets of stable waves with arbitrary velocity in extended systems

Entropía de grafos y su uso para medir la inteligibilidad de la ciudad

Within space cognition studies, Hillier (1996) proposed the concept of intelligibility as a property of space that allows it to be understood by people that either live in or transit through that space. Hillier, in the theory of space syntax, suggests that intelligibility is the correlation between a local variable and a global variable. Basing themselves on the above, Volchenkov and Blanchard (2008) proposed a way to measure intelligibility outside the technical context of the theory of space syntax. This paper returns to theoretical and methodological discussion of Hillier’s work and explains the method proposed by Volchenkov and Blanchard. As an example, the intelligibility of the historic center of the city of San Luis Potosi, Mexico, was measured. It was found that this space has a high intelligibility in the terms of the method proposed by Volchenkov and Blanchard.Dentro de los estudios de cognición del espacio, Hillier (1996) propuso el concepto de inteligibilidad como una propiedad del espacio que permite que éste sea comprendido por las personas que lo transitan y/o habitan. Hillier, dentro de la teoría de la sintaxis del espacio, propone que la inteligibilidad es la correlación entre una variable local y una variable global. Basados en lo anterior, Volchenkov y Blanchard (2008) han propuesto una forma de medir la inteligibilidad fuera del contexto técnico de la teoría de la sintaxis del espacio. Este trabajo recupera la discusión teórica-metodológica del trabajo de Hillier y expone el método de Volchenkov y Blanchard. Como ejemplo del mismo se midió la inteligibilidad del centro histórico de la ciudad de San Luis Potosí, México. Se encontró que dicho espacio tiene una inteligibilidad alta según el método propuesto por Volchenkov y Blanchard. [fr] Dans le cadre des études de la cognition spatiale, Hillier (1996) a proposé le concept d’intelligibilité comme une propriété de l’espace permettant que celui-ci soit compris par les personnes qui y transitent et/ou l’habitent. Hillier propose, dans le contexte de la théorie de la syntaxe spatiale, que l’intelligibilité est la corrélation existante entre une variable locale et une variable globale. Conformément à cette théorie, Volchenkov et Blanchard (2008) ont proposé une méthode pour quantifier l’intelligibilité en dehors du contexte technique de la théorie de la syntaxe spatiale. Le travail ci-présent reprend la discussion théorique et méthodologique du travail de Hillier et expose la méthode de Volchenkov et Blanchard. À titre d’exemple, l’intelligibilité du centre historique de la ville de San Luis Potosí, au Mexique, est quantifiée. Le résultat est que cet espace possède un haut niveau d’intelligibilité selon la méthode proposée par Volchenkov et Blanchard

Dynamical complexity of discrete time regulatory networks

Genetic regulatory networks are usually modeled by systems of coupled differential equations and by finite state models, better known as logical networks, are also used. In this paper we consider a class of models of regulatory networks which present both discrete and continuous aspects. Our models consist of a network of units, whose states are quantified by a continuous real variable. The state of each unit in the network evolves according to a contractive transformation chosen from a finite collection of possible transformations, according to a rule which depends on the state of the neighboring units. As a first approximation to the complete description of the dynamics of this networks we focus on a global characteristic, the dynamical complexity, related to the proliferation of distinguishable temporal behaviors. In this work we give explicit conditions under which explicit relations between the topological structure of the regulatory network, and the growth rate of the dynamical complexity can be established. We illustrate our results by means of some biologically motivated examples.Comment: 28 pages, 4 figure