Multiple orthogonal polynomials of mixed type: Gauss-Borel factorization and the multi-component 2D Toda hierarchy

Multiple orthogonality is considered in the realm of a Gauss--Borel factorization problem for a semi-infinite moment matrix. Perfect combinations of weights and a finite Borel measure are constructed in terms of M-Nikishin systems. These perfect combinations ensure that the problem of mixed multiple orthogonality has a unique solution, that can be obtained from the solution of a Gauss--Borel factorization problem for a semi-infinite matrix, which plays the role of a moment matrix. This leads to sequences of multiple orthogonal polynomials, their duals and second kind functions. It also gives the corresponding linear forms that are bi-orthogonal to the dual linear forms. Expressions for these objects in terms of determinants from the moment matrix are given, recursion relations are found, which imply a multi-diagonal Jacobi type matrix with snake shape, and results like the ABC theorem or the Christoffel--Darboux formula are re-derived in this context (using the factorization problem and the generalized Hankel symmetry of the moment matrix). The connection between this description of multiple orthogonality and the multi-component 2D Toda hierarchy, which can be also understood and studied through a Gauss--Borel factorization problem, is discussed. Deformations of the weights, natural for M-Nikishin systems, are considered and the correspondence with solutions to the integrable hierarchy, represented as a collection of Lax equations, is explored. Corresponding Lax and Zakharov--Shabat matrices as well as wave functions and their adjoints are determined. The construction of discrete flows is discussed in terms of Miwa transformations which involve Darboux transformations for the multiple orthogonality conditions. The bilinear equations are derived and the $\tau$-function representation of the multiple orthogonality is given.Comment: 53 pages. In this version minor revisions regarding the Christoffel-Darboux operators are performe

Soft-404 Pages, A Crawling Problem

[Absctract]: During its traversal of the Web, crawler systems have to deal with multiple challenges. Some of them are related with detecting garbage content to avoid wasting resources processing it. Soft-404 pages are a type of garbage content generated when some web servers do not use the appropriate HTTP response code for death links making them to be incorrectly identified. Our analysis of the Web has revealed that 7.35% of web servers send a 200 HTTP code when a request for an unknown document is received, instead of a 404 code, which indicates that the document is not found. This paper presents a system called Soft404Detector, based on web content analysis to identify web pages that are Soft-404 pages. Our system uses a set of content-based heuristics and combines them with a C4.5 classifier. For testing purposes, we built a Soft-404 pages dataset. Our experiments indicate that our system is very effective, achieving a precision of 0.992 and a recall of 0.980 at Soft-404 pages.This research was supported by Xunta de Galicia CN2012/211, the Ministry of Education and Science of Spain and FEDER funds of the European Union (Project TIN2009-14203).Xunta de Galicia; CN2012/21

Distributed and Collaborative Web Change Detection System

[Absctract]: Search engines use crawlers to traverse the Web in order to download web pages and build their indexes. Maintaining these indexes up-to-date is an essential task to ensure the quality of search results. However, changes in web pages are unpredictable. Identifying the moment when a web page changes as soon as possible and with minimal computational cost is a major challenge. In this article we present the Web Change Detection system that, in a best case scenario, is capable to detect, almost in real time, when a web page changes. In a worst case scenario, it will require, on average, 12 minutes to detect a change on a low PageRank web site and about one minute on a web site with high PageRank. Meanwhile, current search engines require more than a day, on average, to detect a modification in a web page (in both cases).This research was supported by Xunta de Galicia CN2012/211, the Ministry of Education and Science of Spain and FEDER funds of the European Union (Project TIN2009- 14203).Xunta de Galicia; CN2012/21

Breaking the Waves: Earthquake and Tsunami Research in the Iberian Peninsula from a Historiographical Perspective.

Política de acceso abierto consultada en http://biblioteca.cchs.csic.es/registro_buscareditoriales.php?id=828This chapter performs a historiographical overview for the purpose of describing the evolution of recent earthquake and tsunami research in the Iberian Peninsula, characterised by the convergence of information deriving from different scientific disciplines, such as historical seismology, geology and archaeology. From the early 1990s down to the present day, several stages of research are identified, while placing the spotlight on the boom years in geological research on paleotsunamis in Portugal and Spain, in the wake of the catastrophic tsunamis in the Indian Ocean in 2004 and in Japan in 2011, as well as addressing future perspectives for interdisciplinary collaboration. The final section describes the aim of this book, plus the organisation and content of its chapters, as well as reflects on the future challenges facing research in this field.Project ‘The Tsunami in the Cultural Representations of the Ancient World: Gadir-Gades and the Gulf of Cádiz as a case study’ (HAR2015-66011-P, MINECO-FEDER). Project ‘Earthquakes and Tsunamis in the Iberian Peninsula: Social Responses in the longue durée’ (PGC2018-093752-B-I00, MCI/AEI/FEDER, UE)

The multicomponent 2D Toda hierarchy: generalized matrix orthogonal polynomials, multiple orthogonal polynomials and Riemann-Hilbert problems

15 pages.-- ArXiv pre-print available at: http://arxiv.org/abs/0911.0941Submitted to: Inverse ProblemsWe consider the relation of the multi-component 2D Toda hierarchy with matrix orthogonal and biorthogonal polynomials. The multi-graded Hankel reduction of this hierarchy is considered and the corresponding generalized matrix orthogonal polynomials are studied. In particular for these polynomials we consider the recursion relations, and for rank one weights its relation with multiple orthogonal polynomials of mixed type with a type II normalization and the corresponding link with a Riemann--Hilbert problem.MM thanks economical support from the Spanish Ministerio de Ciencia e Innovación, research project FIS2008-00200 and UF thanks economical support from the Spanish Ministerio de Ciencia e Innovación research projects MTM2006-13000-C03-02 and MTM2007-62945 and from Comunidad de Madrid/Universidad Carlos III de Madrid project CCG07-UC3M/ESP-3339.No publicad

A 32-Channel Time-Multiplexed Artifact-Aware Neural Recording System

This paper presents a low-power, low-noise microsystem for the recording of neural local field potentials or intracranial electroencephalographic signals. It features 32 time-multiplexed channels at the electrode interface and offers the possibility to spatially delta encode data to take advantage of the large correlation of signals captured from nearby channels. The circuit also implements a mixed-signal voltage-triggered auto-ranging algorithm which allows to attenuate large interferers in digital domain while preserving neural information. This effectively increases the system dynamic range and avoids the onset of saturation. A prototype, fabricated in a standard 180 nm CMOS process, has been experimentally verified in-vitro with cellular cultures of primary cortical neurons from mice. The system shows an integrated input-referred noise in the 0.5–200 Hz band of 1.4 µVrms for a spot noise of about 85 nV / √Hz. The system draws 1.5 µW per channel from 1.2 V supply and obtains 71 dB + 26 dB dynamic range when the artifact-aware auto-ranging mechanism is enabled, without penalising other critical specifications such as crosstalk between channels or common-mode and power supply rejection ratios

La modalidad e-learning: elementos de un nuevo enfoque de enseñanza

When developing e-learning programs it is necessary to ensure -success by keeping a balance between three main elements: the platform, the contents and the infrastructure. For instance, a good platform with deficient contents renders the system inefficient. And vice versa, a difficult-to-use platform with great contents will make the system worthless. The purpose of this document is to establish the essential criteria to assess the functioning of a e-learning system. Moreover, several recommendations to improve the functionalities of a developing platform will be suggested.Para que haya una mínima garantía de éxito en el desarrollo de la enseñanza e-learning es necesario un cierto equilibrio de calidad entre los tres elementos en que se fundamenta esta modalidad de formación: la herramienta para la formación (la plataforma), los contenidos y la infraestructura necesaria. Una buena plataforma con contenidos deficientes convierten el sistema en ineficiente y, viceversa, magníficos contenidos en una plataforma inmanejable implica que el sistema adquiere la valoración del componente peor. Lo mismo podría decirse de la infraestructura de gestión ya que incide en el sistema de una manera trascendental. El objetivo de este documento es proporcionar una serie de criterios que consideramos esenciales al ahora de valorar el funcionamiento de una plataforma formativa. Además, se aportan una serie de recomendaciones básicas que podría ayudar a mejorar las funcionalidades de una plataforma en desarrollo

Una revisión sobre gamificación en historia y geografía

Inicialmente, conviene conceptualizar el término gamificación, así como contextualizarlo: así, de acuerdo con Werbach (2012), y en la misma línea que otros autores, como Attali y Arieli-Attali (2015) y González et al. (2016), la gamificación hace referencia a la utilización de elementos de juegos y técnicas para diseñar juegos en contextos no lúdicos; por otro lado, en lo referente a su contextualización, puede ser aplicada en diferentes ámbitos, como el empresarial, educativo, cultural, deportivo, etc., en consonancia con Valderrama (2015)

El concepto de eficiencia de los modelos de calibración en Fluorescencia de Rayos X

Los efectos interelementales constituyen la limitante más importante en lo que se refiere a la exactitud de los resultados de los análisis por Fluorescencia de Rayos X. No corregir estos efectos, o hacerlo incorrectamente durante el paso de calibración, conduce a la introducción de errores sistemáticos severos que afectarán significativamente la confiabilidad de los resultados analíticos. Diferentes modelos matemáticos de corrección de los efectos interelementales han sido desarrollados para la calibración en el análisis por Fluorescencia de Rayos X (FRX). Las magnitudes frecuentemente utilizadas para evaluar dichos modelos presentan algunas limitaciones. En este trabajo se plantea la utilización del concepto de eficiencia de los modelos de calibración y de la magnitud DELTA, recientemente propuesta para estimar esa eficiencia. Esta magnitud de significación estadística, que tiene un carácter general, está orientada a la predicción y es representable gráficamente. Por las características de la calibración en ese método instrumental, se realizó una extensión a los casos en que el error aleatorio asociado a la preparación de las muestras de referencia es mayor que el de la estimación. Se compararon dos de los modelos de corrección más empleados en FRX: el de Lucas-Tooth y el de De Jongh. Se estudió la normalidad de las poblaciones de las concentraciones estimadas a partir de los datos experimentales y mediante simulaciones computacionales. La comparación de los resultados con las diversas magnitudes propuestas y la magnitud Delta demostró las ventajas que tiene esta última para la detección de errores sistemáticos en la calibración

La implantación de las tecnologías de la información y la comunicación en los centros educativos de la comunidad de Madrid. Impacto en la docencia y en los alumnos

La valoración, amplia y detallada, de los diferentes aspectos de la implantación de las Tecnologías de la Información y de la Comunicación (TIC) en los centros educativos es imprescindible para conocer la realidad de esta incorporación a la actividad educativa cotidiana mejorar, progresivamente, su adaptación en todos los ámbitos educativos. Se presenta aquí un proyecto en marcha que consiste en una investigación surgida de una colaboración entre el Departamento de Didáctica y Teoría de la Educación de la Universidad Autónoma de Madrid (UAM) y la Consejería de Educación de la Comunidad Autónoma de Madrid. El objetivo es realizar una valoración de los aspectos materiales, personales y funcionales que confluyen en la implantación de las TIC en los centros educativos de dicha comunidad, así como su impacto en la docencia y en los alumnos. El plan objeto de estudio, inició en abril de 2002 las actuaciones del Plan Global para el desarrollo de las TIC en los centros docentes, Educamadrid, con el objetivo de impulsar la plena incorporación del sistema educativo madrileño a la Sociedad de la Información. En esta investigación se utiliza la encuesta como herramienta básica y los procesos de aplicación están informatizados. Ello permitirá obtener información de una gran cantidad de sujetos de forma rápida y económica, siendo posible, de esta forma, obtener datos de toda la población de estudio. Son tres los cuestionarios desarrollados: uno dirigido al Director del Centro, otro al Coordinador TIC en el centro y, el tercero, al Asesor de TIC de los centros de actualización pedagógica. El estudio se realiza sobre totalidad de los centros educativos no universitarios de la Comunidad y abarca las etapas y enseñazas siguientes: Educación Infantil, Educación Primaria, Educación Secundaria (IES, FP), Educación de Régimen Especial (Escuelas de Idiomas, Enseñanzas artísticas), Educación de Personas Adultas y Centros de Apoyo al Profesorado. El modelo de evaluación utilizado es el llamado CIPP “Contexto‐Entrada‐Proceso‐Producto”. Estas fases se estudian a través de unos indicadores perfectamente definidos y sobre los que se obtendrá la información necesaria.A wide and detailed valuation of the different aspects of the introduction of Information and Communication Technologies (ICT) at schools it is essential in order to understand its reality in the daily educational activity and to improve, progressively, its adaptation in all the educational fields. A working project is enclosed here and consists of an investigation arisen from a collaboration between the Department of Didactics and Theory of the Education of the Universidad Autónoma de Madrid (UAM) and the Department of Education of the Comunidad Autónoma de Madrid. The objective is to make a valuation of the material, personal and functional aspects that come together in the implantation of TIC at schools of this community, as well as its impact on teaching and students. In April of 2002 the plan of this object of study started the performances of the Global Plan for the development of the ICT in the teaching institutions, Educamadrid, with the objective of giving way to the total incorporation of Madrid’s educational system to the Information Society. In this investigation the survey is used as a basic tool and the application processes are computerized. It will allow to obtain data from a great amount of people in a fast and economic way, being possible, of this way, to collect data of all the population of study. There are three developed questionnaires: one addressed to the Director of the Centre, another one to the ICT Coordinator in the centres and, third, to the ICT Adviser of the centres of pedagogical update. This study is made on all the non‐university educational centres of the Community and includes the following: kindergarten, Primary and Secondary Education, Special Regime Education (Schools of Languages, artistic Lessons), Education of Adult People and Centres of Teaching staff support. The used model of evaluation is called CIPP “Context‐Input‐Process‐Product”. These phases are studied through perfectly defined indicators and on which the necessary information will be obtained