An agent-based model of firm location with different regional policies

This paper presents an agent based model of firm location designed to explore the effect of regional policies on the spatial pattern of business activity. New firms are created each period taking into account the sector profitability and entry barriers. Firms choose their location and then they decide sequentially whether change their size or cease their activity accordingly to the profit maximization principle and the limited information they have. Their costs depend not only on the production level and the price of the productive factors but also on the land price. The characteristics of the territory where the firms are located are not static but rather evolve depending on the public policies, demographic variables and the firm localization patterns. The presented model shows endogenous rules of firm localization as well as the effects in the medium and long term of public policies

Microbiota depletion promotes human rotavirus replication in an adult mouse model

Intestinal microbiota-virus-host interaction has emerged as a key factor in mediating enteric virus pathogenicity. With the aim of analyzing whether human gut bacteria improve the inefficient replication of human rotavirus in mice, we performed fecal microbiota transplant (FMT) with healthy infants as donors in antibiotic-treated mice. We showed that a simple antibiotic treatment, irrespective of FMT, resulted in viral shedding for 6 days after challenge with the human rotavirus G1P[8] genotype Wa strain (RVwa). Rotavirus titers in feces were also significantly higher in antibiotic-treated animals with or without FMT but they were decreased in animals subject to self-FMT, where a partial re-establishment of specific bacterial taxons was evidenced. Microbial composition analysis revealed profound changes in the intestinal microbiota of antibiotic-treated animals, whereas some bacterial groups, including members of Lactobacillus, Bilophila, Mucispirillum, and Oscillospira, recovered after self-FMT. In antibiotic-treated and FMT animals where the virus replicated more efficiently, differences were observed in gene expression of immune mediators, such as IL1β and CXCL15, as well as in the fucosyltransferase FUT2, responsible for H-type antigen synthesis in the small intestine. Collectively, our results suggest that antibiotic-induced microbiota depletion eradicates the microbial taxa that restrict human rotavirus infectivity in mice

Signatures of a two-dimensional ferromagnetic electron gas at the La_(0.7)Sr_(0.3)MnO_(3)/SrTiO_(3) interface arising from orbital reconstruction

The magnetoresistance of La0.7Sr0.3MnO3/SrTiO3La0.7Sr0.3MnO3/SrTiO3 superlattices with magnetic field rotating out-of-plane shows unexpected peaks for in-plane fields. Resistivity calculations with spin–orbit coupling reveal that orbital reconstruction at the manganite interface leads to a 2D ferromagnetic electron gas coupled antiparallel to the manganite “bulk”. These orbital and magnetic reconstructions are supported by X-ray linear dichroism and ab initio calculations

Ferroionic inversion of spin polarization in a spin-memristor

Magnetoelectric coupling in artificial multiferroic interfaces can be drastically affected by the switching of oxygen vacancies and by the inversion of the ferroelectric polarization. Disentangling both effects is of major importance toward exploiting these effects in practical spintronic or spinorbitronic devices. We report on the independent control of ferroelectric and oxygen vacancy switching in multiferroic tunnel junctions with a La_(0.7)Sr_(0.3)MnO_3 bottom electrode, a BaTiO_3 ferroelectric barrier, and a Ni top electrode. We show that the concurrence of interface oxidation and ferroelectric switching allows for the controlled inversion of the interface spin polarization. Moreover, we show the possibility of a spin-memristor where the controlled oxidation of the interface allows for a continuum of memresistance states in the tunneling magnetoresistance. These results signal interesting new avenues toward neuromorphic devices where, as in practical neurons, the electronic response is controlled by electrochemical degrees of freedom

Controlled sign reversal of electroresistance in oxide tunnel junctions by electrochemical-ferroelectric coupling

The persistence of ferroelectricity in ultrathin layers relies critically on screening or compensation of polarization charges which otherwise destabilize the ferroelectric state. At surfaces, charged defects play a crucial role in the screening mechanism triggering novel mixed electrochemical-ferroelectric states. At interfaces, however, the coupling between ferroelectric and electrochemical states has remained unexplored. Here, we make use of the dynamic formation of the oxygen vacancy profile in the nanometerthick barrier of a ferroelectric tunnel junction to demonstrate the interplay between electrochemical and ferroelectric degrees of freedom at an oxide interface. We fabricate ferroelectric tunnel junctions with a La_0.7Sr_0.3MnO_3 bottom electrode and BaTiO_3 ferroelectric barrier. We use poling strategies to promote the generation and transport of oxygen vacancies at the metallic top electrode. Generated oxygen vacancies control the stability of the ferroelectric polarization and modify its coercive fields. The ferroelectric polarization, in turn, controls the ionization of oxygen vacancies well above the limits of thermodynamic equilibrium, triggering the build up of a Schottky barrier at the interface which can be turned on and off with ferroelectric switching. This interplay between electronic and electrochemical degrees of freedom yields very large values of the electroresistance (more than 10^6% at low temperatures) and enables a controlled switching between clockwise and counterclockwise switching modes in the same junction (and consequently, a change of the sign of the electroresistance). The strong coupling found between electrochemical and electronic degrees of freedom sheds light on the growing debate between resistive and ferroelectric switching in ferroelectric tunnel junctions, and moreover, can be the source of novel concepts in memory devices and neuromorphie computing

Advances in Computational Social Science and Social Simulation

Aquesta conferència és la celebració conjunta de la "10th Artificial Economics Conference AE", la "10th Conference of the European Social Simulation Association ESSA" i la "1st Simulating the Past to Understand Human History SPUHH".Conferència organitzada pel Laboratory for Socio­-Historical Dynamics Simulation (LSDS-­UAB) de la Universitat Autònoma de Barcelona.Readers will find results of recent research on computational social science and social simulation economics, management, sociology,and history written by leading experts in the field. SOCIAL SIMULATION (former ESSA) conferences constitute annual events which serve as an international platform for the exchange of ideas and discussion of cutting edge research in the field of social simulations, both from the theoretical as well as applied perspective, and the 2014 edition benefits from the cross-fertilization of three different research communities into one single event. The volume consists of 122 articles, corresponding to most of the contributions to the conferences, in three different formats: short abstracts (presentation of work-in-progress research), posters (presentation of models and results), and full papers (presentation of social simulation research including results and discussion). The compilation is completed with indexing lists to help finding articles by title, author and thematic content. We are convinced that this book will serve interested readers as a useful compendium which presents in a nutshell the most recent advances at the frontiers of computational social sciences and social simulation researc

Localización empresarial y economías de aglomeración: el debate en torno a la agregación espacial

El análisis de la incidencia de las economías de aglomeración en la localización empresarial constituye uno de los temas centrales de la Economía Regional. Sin embargo, a pesar de los amplios y sólidos desarrollos teóricos en este campo, los resultados empíricos muestran una preocupante falta de robustez. En este trabajo se analiza una de las posibles causas: el problema de las unidades de área modificables (MAUP). Para ello, tras una revisión de los aspectos económicos y estadísticos ligados al fenómeno, se estima la influencia de las economías de aglomeración en la localización de las empresas en España para cinco divisiones distintas del territorio que incluyen divisiones inframunicipales. Los resultados obtenidos indican que las estimaciones son muy sensibles a la definición de las áreas de análisis por lo que no pueden ser dejadas de lado en la contrastación de hipótesis. Finalmente, se propone una metodología para reducir los inconvenientes derivados del MAUP y aprovechar las posibles ventajas

Industry and Territory Research Group. Department of Economics (Rovira i Virgili University).

El análisis de la incidencia de las economías de aglomeración en la localización empresarial constituye uno de los temas centrales de la Economía Regional. Sin embargo, a pesar de los amplios y sólidos desarrollos teóricos en este campo, los resultados empíricos muestran una preocupante falta de robustez. En este trabajo se analiza una de las posibles causas: el problema de las unidades de área modificables (MAUP). Para ello, tras una revisión de los aspectos económicos y estadísticos ligados al fenómeno, se estima la influencia de las economías de aglomeración en la localización de las empresas en España para cinco divisiones distintas del territorio que incluyen divisiones inframunicipales. Los resultados obtenidos indican que las estimaciones son muy sensibles a la definición de las áreas de análisis por lo que no pueden ser dejadas de lado en la contrastación de hipótesis. Finalmente, se propone una metodología para reducir los inconvenientes derivados del MAUP y aprovechar las posibles ventajas

Economía del cine y del sector audiovisual en España

El intenso desarrollo que ha experimentado el sector audiovisual, tanto por el crecimiento en la demanda de sus servicios, como por la influencia que ejerce sobre otros sectores, ha atraído la atención de sociólogos, políticos y, más recientemente, de los economistas. En este artículo, tras realizar una delimitación y clasificación de los servicios audiovisuales, se estudia su importancia en la economía española, comparando su participación en el conjunto del sector servicios, dedicando una atención especial a las inversiones y al apoyo del sector público que reciben sus diferentes actividades. Por último, se destaca la importancia en este sector de la innovación tecnológica, la globalización y la piratería, que afectan profundamente su desarrollo y determinan su futuro

Localización empresarial y economías de aglomeración: el debate en torno a la agregación espacial

El análisis de la incidencia de las economías de aglomeración en la localización empresarial constituye uno de los temas centrales de la Economía Regional. Sin embargo, a pesar de los amplios y sólidos desarrollos teóricos en este campo, los resultados empíricos muestran una preocupante falta de robustez. En este trabajo se analiza una de las posibles causas: el problema de las unidades de área modificables (MAUP). Para ello, tras una revisión de los aspectos económicos y estadísticos ligados al fenómeno, se estima la influencia de las economías de aglomeración en la localización de las empresas en España para cinco divisiones distintas del territorio que incluyen divisiones inframunicipales. Los resultados obtenidos indican que las estimaciones son muy sensibles a la definición de las áreas de análisis por lo que no pueden ser dejadas de lado en la contrastación de hipótesis. Finalmente, se propone una metodología para reducir los inconvenientes derivados del MAUP y aprovechar las posibles ventajas