The multiregional core-periphery model: the role of the spatial topology

We use the multiregional core-periphery model of the new economic geography to analyze and compare the agglomeration and dispersion forces shaping the location of economic activity for a continuum of network topologies characterized by their degree of centrality, and comprised between two extremes represented by the homogenous (ring) and the heterogeneous (star) configurations. Resorting to graph theory, we systematically extend the analytical tools and graphical representations of the coreperiphery model for alternative spatial configurations, and study the stability of the alternative equilibria in terms of the sustain and break points. We study new phenomena such as the absence of any stable distribution of economic activity for some range of transport costs, and the infeasibility of the dispersed equilibrium in the heterogeneous space, resulting in the introduction of the concept pseudo flat-earth as a long run-equilibrium corresponding to an uneven distribution of economic activity between region

Thermodynamic pathways to genome spatial organization in the cell nucleus

The architecture of the eukaryotic genome is characterized by a high degree of spatial organization. Chromosomes occupy preferred territories correlated to their state of activity and, yet, displace their genes to interact with remote sites in complex patterns requiring the orchestration of a huge number of DNA loci and molecular regulators. Far from random, this organization serves crucial functional purposes, but its governing principles remain elusive. By computer simulations of a Statistical Mechanics model, we show how architectural patterns spontaneously arise from the physical interaction between soluble binding molecules and chromosomes via collective thermodynamics mechanisms. Chromosomes colocalize, loops and territories form and find their relative positions as stable hermodynamic states. These are selected by “thermodynamic switches” which are regulated by concentrations/affinity of soluble mediators and by number/location of their attachment sites along chromosomes. Our “thermodynamic switch model” of nuclear architecture, thus, explains on quantitative grounds how well known cell strategies of upregulation of DNA binding proteins or modification of chromatin structure can dynamically shape the organization of the nucleus

Territorial Developments Based on Graffiti: a Statistical Mechanics Approach

We study the well-known sociological phenomenon of gang aggregation and territory formation through an interacting agent system defined on a lattice. We introduce a two-gang Hamiltonian model where agents have red or blue affiliation but are otherwise indistinguishable. In this model, all interactions are indirect and occur only via graffiti markings, on-site as well as on nearest neighbor locations. We also allow for gang proliferation and graffiti suppression. Within the context of this model, we show that gang clustering and territory formation may arise under specific parameter choices and that a phase transition may occur between well-mixed, possibly dilute configurations and well separated, clustered ones. Using methods from statistical mechanics, we study the phase transition between these two qualitatively different scenarios. In the mean-field rendition of this model, we identify parameter regimes where the transition is first or second order. In all cases, we have found that the transitions are a consequence solely of the gang to graffiti couplings, implying that direct gang to gang interactions are not strictly necessary for gang territory formation; in particular, graffiti may be the sole driving force behind gang clustering. We further discuss possible sociological -- as well as ecological -- ramifications of our results

Spatial patterns and scale freedom in a Prisoner's Dilemma cellular automata with Pavlovian strategies

A cellular automaton in which cells represent agents playing the Prisoner's Dilemma (PD) game following the simple "win-stay, loose-shift" strategy is studied. Individuals with binary behavior, such as they can either cooperate (C) or defect (D), play repeatedly with their neighbors (Von Neumann's and Moore's neighborhoods). Their utilities in each round of the game are given by a rescaled payoff matrix described by a single parameter Tau, which measures the ratio of 'temptation to defect' to 'reward for cooperation'. Depending on the region of the parameter space Tau, the system self-organizes - after a transient - into dynamical equilibrium states characterized by different definite fractions of C agents (2 states for the Von Neumann neighborhood and 4 for Moore neighborhood). For some ranges of Tau the cluster size distributions, the power spectrums P(f) and the perimeter-area curves follow power-law scalings. Percolation below threshold is also found for D agent clusters. We also analyze the asynchronous dynamics version of this model and compare results.Comment: Accepted for publication in JSTA

Building new frontiers: An ecosystemic approach to development, culture, education, environment and quality of life

Quality of life, natural and man-made environments, physical, social and mental well-being are currently undermined by all sorts of hazards and injuries; political, economical, social and cultural disarray normalise atrocious behaviours and violence throughout the world. Considering the multiple problems of difficult settlement or solution in our times, current environmental, social, cultural, educational, political and economic policies and practices are examined in view of new paradigms of growth, power, wealth, work and freedom. A multidimensional ecosystemic approach and planning model for the diagnosis and prognosis of quality of life integrate into a dynamic configuration four dimensions of being-in-the- world (intimate, interactive, social and biophysical), as they induce the events (deficits and assets), cope with consequences (desired or undesired) and reorganise for change, enhancing connexions and sealing ruptures. Development and evaluation of teaching programmes, research projects and public policies benefit from a deep understanding of the events, providing a critical comprehensive four-dimensional framework and planning model for effective and responsible action.education; culture; public policies; environment; ecosystems

Mutual Trust and Cooperation in the Evolutionary Hawks-Doves Game

Using a new dynamical network model of society in which pairwise interactions are weighted according to mutual satisfaction, we show that cooperation is the norm in the Hawks-Doves game when individuals are allowed to break ties with undesirable neighbors and to make new acquaintances in their extended neighborhood. Moreover, cooperation is robust with respect to rather strong strategy perturbations. We also discuss the empirical structure of the emerging networks, and the reasons that allow cooperators to thrive in the population. Given the metaphorical importance of this game for social interaction, this is an encouraging positive result as standard theory for large mixing populations prescribes that a certain fraction of defectors must always exist at equilibrium.Comment: 23 pages 12 images, to appea

Building a Better World: An Ecosystemic Approach to Education, Culture, Health, Environment and Quality of Life

Quality of life, natural and man-made environments, physical, social and mental well-being are currently undermined by all sorts of hazards and injuries; political, economical, social and cultural disarray normalise atrocious behaviours and violence throughout the world. Considering the multiple problems of difficult settlement or solution in our times, current environmental, social, cultural, educational, political and economic policies and practices are examined in view of new paradigms of growth, power, wealth, work and freedom. A multidimensional ecosystemic approach and planning model integrate into a dynamic configuration four dimensions of being-in-the- world (intimate, interactive, social and biophysical), as they induce the events (deficits and assets), cope with consequences (desired or undesired) and reorganise for change.education; culture; public policies; environment; ecosystems