Homophily, Cultural Drift and the Co-Evolution of Cultural Groups

In studies of cultural differentiation, the joint mechanisms of homophily and influence have been able to explain how distinct cultural groups can form. While these mechanisms normally lead to cultural convergence, increased levels of heterogeneity can allow them to produce global diversity. However, this emergent cultural diversity has proven to be unstable in the face of "cultural drift"- small errors or innovations that allow cultures to change from within. We develop a model of cultural differentiation that combines the traditional mechanisms of homophily and influence with a third mechanism of 2network homophily", in which network structure co-evolves with cultural interaction. We show that if social ties are allowed to change with cultural influence, a complex relationship between heterogeneity and cultural diversity is revealed, in which increased heterogeneity can reduce cultural group formation while simultaneously increasing social connectedness. Our results show that in certain regions of the parameter space these co-evolutionary dynamics can lead to patterns of cultural diversity that are stable in the presence of cultural drift.Comment: (8 pages, 8 figures

The logarithmic spiral, autoisoptic curve

In the Line of Investigation that in the department of “Technical Drawing” in the School of Agriculture Engineering of Madrid, we carry out on the study of The Technical Curves and his singularities, we demonstrate an interesting property of the Logarithmic Spiral. The demonstrated property consists of which the logarithmic spiral is a autoisoptic curve, that is to say that if from a point P anyone of the spiral tangent straight lines draw up to the previous arc, these form a constant angle α. This demonstration is novel and in addition we get to contribute a method to calculate the angle α given the equation of the spiral

Desarrollo de la infraestructura y reducción de la pobreza: el caso peruano

In recent years, economic growth and the development of social programs have contributed significantly to poverty reduction in Peru. In this process, the development of infrastructure has been very important in reducing the long term vulnerability of households.This paper examines the role of infrastructure in reducing poverty in households in Peru within a dynamic perspective of poverty and under an asset-based approach. To do this, we estimate Logit models to reflect the impact of different types of infrastructure on the likelihood of being poor in Peru. We also estimate static panel data models (fixed and random effects) to reflect the impact of the different types of infrastructure on the spending ofPeruvian households. Both groups of models are based on information at the household level for the years 2007-2010 from the Peruvian official household survey provided by INEI. These impacts are estimated considering the sex of the household head and the area of residence(urban or rural). For static panel data models, we estimate the impact of the different types of infrastructure on household spending distinguishing whether they are transient poor or chronically poor. Given the data constraints at the household level in Peru, we only analyze the following infrastructures throughout the document: water, sewage, electricity and telecommunications. From the results, we verify a significant and different impact of the various types of infrastructure on poverty according to the area of residence and the gender of the household head. Similarly, we verify a significant and different impact of infrastructure on the types of poverty (transient and chronic poverty).Infraestructura, pobreza, ingresos, enfoque de activos, dinámica de la pobreza.

Espinoso – Gasterosteus aculeatus Linnaeus, 1758

Peces - Orden Gasterosteiformes - Familia Gasterosteidae en la Enciclopedia Virtual de Vertebrados Españoles, http://www.vertebradosibericos.org/. Versiones anteriores: 12-06-2006; 23-10-2009; 25-02-2015A comprehensive review of the natural history of the Western three-spine stickleback Gasterosteus aculeatus in Spain.Peer reviewe

Diseño de un cargador de baterías de 12 voltios haciendo uso de un panel fotovoltaico aplicado en zonas rurales

En el Perú, la electrificación de zonas rurales se ha intensificado debido a programas de electrificación rural elaborados por el Estado y otras entidades no gubernamentales. Sin embargo, hoy en día existen comunidades rurales cuya demanda de potencia en los hogares es cubierta ineficientemente con el uso de baterías de 12 voltios, lo cual genera racionalización del uso de sus artefactos eléctricos, así como los priva de un crecimiento sostenible a nivel socio-económico. Dichas baterías, mayormente de plomo-ácido, son cargadas mediante proveedores externos, lo que causa una dependencia a este servicio e incurre en gastos mensuales mayores a los que ellos demandarían si utilizaran un sistema de recarga fotovoltaica propia. El presente trabajo tomó como muestra a la comunidad de Micaela Bastidas, ubicada al norte del departamento de Lima en la provincia de Barranca, debido a su alto coeficiente de irradiación solar. Se realizó el diseño de un cargador de baterías de 12 voltios para ser utilizado con un panel fotovoltaico y así facilitar la recarga de la misma. Se seleccionaron los componentes adecuados para su diseño, además del panel fotovoltaico y la batería a utilizar, para satisfacer, de manera personalizada, la demanda de potencia promedio a consumir por cada familia de dicha localidad. Se realizaron satisfactoriamente las simulaciones de dicho cargador, con lo que se obtendría una carga óptima de la batería y se prolongaría su vida útil. Por último, en el análisis de costos, se realizó la simulación de venta de un sistema fotovoltaico, por familia, en la comunidad de Micaela Bastidas. Se concluyó que los dos valores agregados principales que sostendrían la competitividad del producto, a nivel nacional, serían: la personalización del diseño del cargador y dimensionamiento del panel fotovoltaico y la batería, según la máxima demanda de potencia promedio actual o futura del usuario, y el suministro de un servicio de asesoría técnica de capacitación y mantenimiento del sistema.Tesi

El planteamiento y el análisis del desarrollo de la prospección: dos capítulos olvidados en los trabajos de arqueología territorial

Althoug studies based on survey have increased or improved, and at the same time there have been good efforts to design a working plan for projects of Territorial Archaeology, in most of these studies, a discussion of the survey plan and the analysis of this plan have been omitted. For this reason, our purpose in this paper is to draw attention to this lack and propose a series of suggestions for the analysis of surveys: number of runs, time of day, circumstances and chronology of discoveries, experience, productivity and the results obtained in different topographic and ecological areas.Pese a la multiplicación y mejora de los estudios basados en la prospección y los notables intentos por diseñar un esquema de trabajo para los proyectos de «Arqueología Territorial», se echa en falta en la generalidad de los trabajos un verdadero apartado en el que se recoja el planteamiento de la prospección y se realice un análisis de su desarrollo. Nuestro objetivo en este artículo es precisamente llamar la atención sobre esta carencia y proponer una serie de parámetros para el análisis de la prospección: número de recorridos, horario de localización, circunstancias y cronología de los hallazgos, el factor experiencia, la productividad y los resultados obtenidos en las diferentes áreas topográfico-ecológicas

Revisión nomenclatural y propuesta sintaxonómica de la vegetación de humedales turbosos de la región Valdiviano-Magallánica

Although numerous descriptive studies have been published throughout the 20th century on peat communities in the Southern Cone of South America, the nomenclature applied to the different units recognised often fails to take into account the proposals of previous authors. Our aim is to clarify the nomenclature by applying the rules of the ICPN to propose a current syntaxonomy of the class Myrteolo nummulariae-Sphagnetea magellanici. After a bibliographic compilation of possible peatland associations from the part of South America between parallels 40º and 56º south, under Temperate and Boreal macroclimates, we have collected around 30 names of phytosociological associations and alliances containing an abundance of homonyms and nomina nuda. Following ICPN standards, we have eliminated duplications and established priority names over others, lectotypified some names and rejected others as nomen ambiguum. We have arranged the floristic groups in the recognised associations in synthetic tables, with some nomina nudawhose characterisation we interpret as doubtful, as a proposed syntaxonomical organisation of the phytosociological class.The various communities recognised by the different authors who have worked in the territory can be divided into four physiognomic groups: 1. cushion bogs, 2. Sphagnumbogs 3. “montane tundra” bogs and 4. sedge-grass bogs. The syntaxonomic grouping we propose for the 13 associations recognised as nomenclaturally valid can be summarised as follows: a single class, Myrteolo nummulariae-Sphagnetea magellanici, is accepted, with a single order, Myrteolo-Sphagnetalia, and three alliances: Astelio pumilae-Oreobolion obtusanguli with seven associations (coinciding with type 1), Gaultherio-Sphagnion magellanici with four associations (type 2), and Abrotanello linearifoliae-Bolacion caespitosae with two associations (type 3). We contest the validity of around 22 names of syntaxa of different ranks, while acknowledging that more studies are required, particularly to define and delimit type 4 peatland communitiesA lo largo del siglo XX se han realizado numerosos estudios descriptivos de comunidades turbosas por el Cono-Sur sudamericano, pero con frecuencia la nomenclatura aplicada a las distintas unidades reconocidas no tenía en cuenta las propuestas de autores anteriores. Nuestro objetivo ha sido clarificar la Nomenclatura aplicando las reglas del CINF para proponer una sintaxonomía de la clase Myrteolo nummulariae-Sphagnetea magellanici. Tras una recopilación bibliográfica de asociaciones de turberas de la parte de Sudamérica comprendida entre los paralelos 40º y 56º sur, bajo macroclimas Templado y Boreal, se han reunido alrededor de unos 30 nombres de asociaciones y alianzas fitosociológicas entre los que abundan homonimias y nomina nuda. Aplicando las normas del ICPN se han eliminado duplicidades, establecido nombres prioritarios sobre otros, lectotipificado algunos nombres y rechazado algún otro como nomen ambiguum. Los conjuntos florísticos de las asociaciones reconocidas, junto con algunas nomina nudacuya caracterización interpretamos como dudosa, se han reunido en tablas sintéticas como propuesta de organización sintaxonómica de la clase fitosociológica.La diversidad de comunidades que han reconocido los distintos autores que han trabajado en este territorio se puede repartir en 4 grupos fisionómicos: 1. turberas pulvinadas, 2. turberas esfagnosas 3. turberas de “tundra montana” y 4. turberas cipero-graminoides. La agrupación sintaxonómica que proponemos para las 13 asociaciones reconocidas como nomenclaturalmente válidas se resume en: una única clase Myrteolo nummulariae-Sphagnetea magellanici, con un orden único, Myrteolo-Sphagnetalia, y tres alianzas: Astelio pumilae-Oreobolion obtusanguli con 7 asociacionesS

Supersymmetric partners of the one-dimensional infinite square well Hamiltonian

We find supersymmetric partners of a family of self-adjoint operators which are self-adjoint extensions of the differential operator −d 2 / dx2 on L2 [−a, a], a > 0, that is, the one dimensional infinite square well. First of all, we classify these self-adjoint extensions in terms of several choices of the parameters determining each of the extensions. There are essentially two big groups of extensions. In one, the ground state has strictly positive energy. On the other, either the ground state has zero or negative energy. In the present paper, we show that each of the extensions belonging to the first group (energy of ground state strictly positive) has an infinite sequence of supersymmetric partners, such that the l-th order partner differs in one energy level from both the (l − 1)-th and the ( l + 1)-th order partners. In general, the eigenvalues for each of the self-adjoint extensions of −d2 / dx2 come from a transcendental equation and are all infinite. For the case under our study, we determine the eigenvalues, which are also infinite, all the extensions have a purely discrete spectrum, and their respective eigenfunctions for all of its l-th supersymmetric partners of each extensio

Information Feedback and Mass Media Effects in Cultural Dynamics

We study the effects of different forms of information feedback associated with mass media on an agent-agent based model of the dynamics of cultural dissemination. In addition to some processes previously considered, we also examine a model of local mass media influence in cultural dynamics. Two mechanisms of information feedback are investigated: (i) direct mass media influence, where local or global mass media act as an additional element in the network of interactions of each agent, and (ii) indirect mass media influence, where global media acts as a filter of the influence of the existing network of interactions of each agent. Our results generalize substantiate previous findings showing that cultural diversity builds-up by increasing the strength of the mass media influence. We find that this occurs independently of the mechanisms of action (direct or indirect) of the mass media message. However, through an analysis of the full range of parameters measuring cultural diversity, we establish that the enhancement of cultural diversity produced by interaction with mass media only occurs for strong enough mass media messages. In comparison with previous studies a main different result is that weak mass media messages, in combination with agent-agent interaction, are efficient in producing cultural homogeneity. Moreover, the homogenizing effect of weak mass media messages are more efficient for direct local mass media messages than for global mass media messages or indirect global mass media influences.Agent Based Model, Culture, Dissemination, Mass Media

Multifractal analysis of discretized X-ray CT images for the characterization of soil macropore structures

A correct statistical model of soil pore structure can be critical for understanding flow and transport processes in soils, and creating synthetic soil pore spaces for hypothetical and model testing, and evaluating similarity of pore spaces of different soils. Advanced visualization techniques such as X-ray computed tomography (CT) offer new opportunities of exploring heterogeneity of soil properties at horizon or aggregate scales. Simple fractal models such as fractional Brownian motion that have been proposed to capture the complex behavior of soil spatial variation at field scale rarely simulate irregularity patterns displayed by spatial series of soil properties. The objective of this work was to use CT data to test the hypothesis that soil pore structure at the horizon scale may be represented by multifractal models. X-ray CT scans of twelve, water-saturated, 20-cm long soil columns with diameters of 7.5 cm were analyzed. A reconstruction algorithm was applied to convert the X-ray CT data into a stack of 1480 grayscale digital images with a voxel resolution of 110 microns and a cross-sectional size of 690 × 690 pixels. The images were binarized and the spatial series of the percentage of void space vs. depth was analyzed to evaluate the applicability of the multifractal model. The series of depth-dependent macroporosity values exhibited a well-defined multifractal structure that was revealed by singularity and Rényi spectra. The long-range dependencies in these series were parameterized by the Hurst exponent. Values of the Hurst exponent close to one were observed indicating the strong persistence in variations of porosity with depth. The multifractal modeling of soil macropore structure can be an efficient method for parameterizing and simulating the vertical spatial heterogeneity of soil pore space