118 research outputs found
The role of homophily in the emergence of opinion controversies
Understanding the emergence of strong controversial issues in modern
societies is a key issue in opinion studies. A commonly diffused idea is the
fact that the increasing of homophily in social networks, due to the modern
ICT, can be a driving force for opinion polariation. In this paper we address
the problem with a modelling approach following three basic steps. We first
introduce a network morphogenesis model to reconstruct network structures where
homophily can be tuned with a parameter. We show that as homophily increases
the emergence of marked topological community structures in the networks
raises. Secondly, we perform an opinion dynamics process on homophily dependent
networks and we show that, contrary to the common idea, homophily helps
consensus formation. Finally, we introduce a tunable external media pressure
and we show that, actually, the combination of homophily and media makes the
media effect less effective and leads to strongly polarized opinion clusters.Comment: 24 pages, 10 figure
A thermodynamic counterpart of the Axelrod model of social influence: The one-dimensional case
We propose a thermodynamic version of the Axelrod model of social influence.
In one-dimensional (1D) lattices, the thermodynamic model becomes a coupled
Potts model with a bonding interaction that increases with the site matching
traits. We analytically calculate thermodynamic and critical properties for a
1D system and show that an order-disorder phase transition only occurs at T = 0
independent of the number of cultural traits q and features F. The 1D
thermodynamic Axelrod model belongs to the same universality class of the Ising
and Potts models, notwithstanding the increase of the internal dimension of the
local degree of freedom and the state-dependent bonding interaction. We suggest
a unifying proposal to compare exponents across different discrete 1D models.
The comparison with our Hamiltonian description reveals that in the
thermodynamic limit the original out-of-equilibrium 1D Axelrod model with noise
behaves like an ordinary thermodynamic 1D interacting particle system.Comment: 19 pages, 5 figure
Urban skylines from Schelling model
We propose a metapopulation version of the Schelling model where two kinds of
agents relocate themselves, with unconstrained destination, if their local
fitness is lower than a tolerance threshold. We show that, for small values of
the latter, the population redistributes highly heterogeneously among the
available places. The system thus stabilizes on these heterogeneous skylines
after a long quasi-stationary transient period, during which the population
remains in a well mixed phase. Varying the tolerance passing from large to
small values, we identify three possible global regimes: microscopic clusters
with local coexistence of both kinds of agents, macroscopic clusters with local
coexistence (soft segregation), macroscopic clusters with local segregation but
homogeneous densities (hard segregation). The model is studied numerically and
complemented with an analytical study in the limit of extremely large node
capacity.Comment: 16 pages, 10 figure
The detection and effect of social events on Wikipedia data-set for studying human preferences
Several studies have used Wikipedia (WP) data-set to analyse worldwide human preferences by languages. However, those studies could suffer from bias related to exceptional social circumstances. Any massive event promoting exceptional editions of WP can be defined as a source of bias. In this article, we follow a procedure for detecting outliers. Our study is based on 12 languages and 13 different categories. Our methodology defines a parameter, which is language-dependent instead of being externally fixed. We also study the presence of human cyclic behavior to evaluate apparent outliers. After our analysis, we found that the outliers in our data-set do not significantly affect the analysis of preferences by categories among different WP languages. While investigating the possibility of bias related to exceptional social circumstances is always a safe measure before doing any analysis on Big Data, we found that in the case of the first ten years of the Wikipedia data-set, outliers do not significantly affect using Wikipedia data-set as a digital footprint to analyse worldwide human preferences
Seismic risk scenarios for buildings in Mérida, Venezuela. Detailed vulnerability assessment for non-engineered housing
Este trabajo presenta un estudio de riesgo sÃsmico para los edificios de Mérida, Venezuela. Consiste en una evaluación de la amenaza y de la vulnerabilidad sÃsmicas para toda la ciudad y en un estudio más detallado de la vulnerabilidad de viviendas de autoconstrucción en el Barrio de "La Milagrosa".Se describe la ciudad de Mérida y su evolución durante sus más de 400 años de historia. Se lleva a cabo una evaluación de su peligrosidad sÃsmica. El marco tectónico asà como las zonas sismogenéticas se toman de otros estudios. Se efectúa un análisis probabilÃstico no zonificado, obteniendo los perÃodos de retorno y las probabilidades anuales de excedencia de terremotos de grado I = VI a I = IX según la Escala MacrosÃsmica Europea. Las aceleraciones máximas horizontales para estos eventos se estiman mediante una ley de atenuación deducida especialmente para el oeste de Venezuela. Estas aceleraciones se utilizan para efectuar una serie representativa de análisis de la respuesta (en la meseta). Los perÃodos máximos obtenidos asà como los correspondientes factores de amplificación se utilizan para realizar una Microzonificación de dicha meseta. Los efectos inducidos (licuefacción y deslizamientos) se estiman mediante la metodologÃa de estimación de pérdidas sÃsmicas HAZUS®.Se utilizan dos metodologÃas de evaluación de la vulnerabilidad: IVIM y LM1. LM1 proporciona distribuciones de vulnerabilidad para Mérida; éstas permiten concluir de manera preliminar que la mayor parte de las construcciones de "La Milagrosa" (y de otros asentamientos informales) son altamente vulnerables. IVIM se utiliza para llevar a cabo una evaluación más detallada de la vulnerabilidad de estas construcciones; la información sobre éstas se adquiere estudiando los informes de daños para situaciones similares, intentando comprender su comportamiento frente a acciones sÃsmicas y efectuando un análisis de tres edificios prototipo (de una, dos y tres plantas) según la normativa sismorresistente Venezolana. La evaluación por la metodologÃa IVIM permite clasificar a las construcciones según sus Ãndices de vulnerabilidad. Esta información se utiliza para efectuar un nuevo estudio dentro de "La Milagrosa" (con la metodologÃa LM1) para obtener escenarios de daño.Se proponen soluciones preliminares para construcción sismorresistente de nuevos edificios y para acondicionamiento de edificios existentes. Se incluye un balance económico coste-beneficio.Se presentan escenarios globales de daño obtenidos con la metodologÃa LM1. El sistema de información geográfica ArcView® utilizado en esta investigación proporciona distintas maneras de presentar la información disponible. La distribución del daño en la ciudad se ilustra especialmente mediante los distintos grados de daño (para las intensidades escenario) como porcentaje de los edificios en los subsectores.This work presents a seismic risk assessment on the buildings of Mérida, Venezuela. It consists of a global hazard and vulnerability evaluation and a deeper vulnerability analysis for non-engineered constructions at the "La Milagrosa" settlement.The city of Mérida and its physical evolution throughout more than 400 years is described. A seismic hazard assessment is performed. The tectonic framework as well as the seismogenic zones are taken from other studies. A non-zonified probabilistic analysis is performed obtaining the return periods and annual exceedance probabilities for events corresponding to the European Macroseismic Scale intensity degrees from I = VI to I = IX. The expected horizontal PGAs for these events are estimated by means of a specially derived attenuation law for western Venezuela. These accelerations are used for a number of representative site response analyses (in the plateau). The obtained maximum amplification periods and the corresponding amplification factors are used to carry out a microzonation of the Mérida plateau. Possible induced effects such as liquefaction and landsliding are estimated by the HAZUS® Earthquake Loss Estimation Methodology.Two vulnerability assessment methodologies (IVIM and LM1) are used. LM1 provides vulnerability distributions for Mérida; they allow preliminarily concluding that most of the constructions at "La Milagrosa" (and other informal settlements) are highly vulnerable. IVIM is used to perform a more detailed vulnerability evaluation of these constructions; the required knowledge about them is acquired by studying the available damage reports for similar situations, by trying to understand their seismic behavior and by performing a code type analysis (following Venezuelan regulations) on three prototype buildings (with one, two and three floors, respectively). The output of the evaluation by the IVIM is a classification of the constructions according their vulnerability indices. This information is used to perform a new study inside "La Milagrosa" with LM1 methodology providing local damage scenarios.Preliminary solutions for earthquake resistant construction of new buildings and for seismic strengthening of existing ones are proposed. A Cost-Benefit analysis is presented.Global damage scenarios obtained by the LM1 method are presented. Several manners to display this information are available through the GIS ArcView® software used in this research; the distribution of the different damage grades occurring at the scenario intensities as a percentage of the total number of buildings in the sub-sectors, is primarily used to display the damage distribution in the city.Postprint (published version
Bounded confidence models generate more secondary clusters when the number of agents is growing
We study the bounded confidence model on a growing population. We compare
simulations of the agent model, its version in continuous densities and with
the standard influence function or a smoother influence function. We find that
the model on a growing population generates bigger secondary clusters and more
systematically than when the population is fixed. Moreover, our tests with the
smooth influence function suggest that these secondary clusters can be
generated by a different mechanism when the population is growing than when it
is fixed.Comment: 16 pages, 8 figure
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