Two-step arithmetic word problems

This study uses the perspective of schemes to analyze characteristics of arithmetic word problems that can influence the process of translation from the verbal statement to an arithmetical representation. One characteristic that we have detected in the two-step word problems is the presence of one or two connections (nodes) in schemes that represent them, and this paper explores whether the number of nodes affects the activation of the associated schemas. With students from the 5th and 6th grades of elementary school (11 and 12 years of age), we analyze the written productions and would stress that the number of connections influences the activation of the right schema. Results show that the double connection implicate a greater difficulty for obtaining a correct arithmetical representation. Likewise, the presence of a simple or double connection between the two relationships means that the students commit specific errors that we associate with this characteristic

Modelo de controlador borroso completamente programable de altas prestaciones y su desarrollo

La presente Tesis Doctoral propone un modelo novedoso para la ejecución con altas prestaciones de sistemas borrosos completamente programables en arquitecturas estándar. El modelo desarrollado permite aplicar las técnicas borrosas a nuevos campos en los que hasta ahora no se habían aplicado debido a que no se podían ejecutar a la velocidad suficiente, no se disponían de las capacidades de programación necesarias o una combinación de ambas. Fruto del estudio del estado del arte se llega a la conclusión de que para conseguir procesamiento con altas prestaciones en plataformas estándar es necesaria una fase de compilación que adapte el conocimiento expresado en un sistema borroso a la arquitectura que lo va a ejecutar. El modelo propuesto introduce el concepto de compilación aproximada. Éste concepto se basa en que el diseño de todo sistema borroso es inherentemente aproximado. La compilación aproximada se basa en respetar el sistema borroso original en aquellos puntos en los que el diseñador tiene una certeza total, y generar una aproximación en aquellos en los que no la tiene. Asimismo, el modelo dispone de mecanismos para garantizar una cota de error máxima. El modelo desarrollado puede presentarse también como un aproximador universal, con la ventaja de que su demostración se realiza por construcción. Para la obtención de altas prestaciones ha sido clave tanto la elección de las plataformas de ejecución como la optimización del código obtenido para las mismas. Se detallan los motivos para la elección de las plataformas y las optimizaciones realizadas. Asimismo, se diseña una arquitectura para los motores de inferencia borrosos independientes de plataforma y basada en una memoria caché de interpolación, para que proporcione altas prestaciones. La Tesis Doctoral realiza un estudio de la arquitectura típica de las soluciones borrosas, enumerando las conclusiones en dos hipótesis. Estas hipótesis sirven como base para proponer las arquitecturas óptimas para ejecución de sistemas borrosos y poder garantizar unos tiempos de ejecución mínimos para cualquier sistema

Querying Spatio-temporal Patterns in Mobile Phone-Call Databases

Abstract — Call Detail Record (CDR) databases contain millions of records with information about cell phone calls, including the position of the user when the call was made/received. This huge amount of spatiotemporal data opens the door for the study of human trajectories on a large scale without the bias that other sources (like GPS or WLAN networks) introduce in the population studied. Also, it provides a platform for the development of a wide variety of studies ranging from the spread of diseases to planning of public transport. Nevertheless, previous work on spatiotemporal queries does not provide a framework flexible enough for expressing the complexity of human trajectories. In this paper we present the Spatiotemporal Pattern System (STPS) to query spatiotemporal patterns in very large CDR databases. STPS defines a regular-expression query language that is intuitive and that allows for any combination of spatial and temporal predicates with constraints, including the use of variables. The design of the language took into consideration the layout of the areas being covered by the cellular towers, as well as “areas ” that label places of interested (e.g. neighborhoods, parks, etc) and topological operators. STPS includes an underlying indexing structure and algorithms for query processing using different evaluation strategies. A full implementation of the STPS is currently running with real, very large CDR databases on Telefónica Research Labs. An extensive performance evaluation of the STPS shows that it can efficiently find complex mobility patterns in large CDR databases. I

Assessing the Potential of Ride-Sharing Using Mobile and Social Data

Ride-sharing on the daily home-work-home commute can help individuals save on gasoline and other car-related costs, while at the same time it can reduce traffic and pollution. This paper assesses the potential of ride-sharing for reducing traffic in a city, based on mobility data extracted from 3G Call Description Records (CDRs, for the cities of Barcelona and Madrid) and from Online Social Networks (Twitter, collected for the cities of New York and Los Angeles). We first analyze these data sets to understand mobility patterns, home and work locations, and social ties between users. We then develop an efficient algorithm for matching users with similar mobility patterns, considering a range of constraints. The solution provides an upper bound to the potential reduction of cars in a city that can be achieved by ride-sharing. We use our framework to understand the different constraints and city characteristics on this potential benefit. For example, our study shows that traffic in the city of Madrid can be reduced by 59% if users are willing to share a ride with people who live and work within 1 km; if they can only accept a pick-up and drop-off delay up to 10 minutes, this potential benefit drops to 24%; if drivers also pick up passengers along the way, this number increases to 53%. If users are willing to ride only with people they know ("friends" in the CDR and OSN data sets), the potential of ride-sharing becomes negligible; if they are willing to ride with friends of friends, the potential reduction is up to 31%.Comment: 11 page

Influence of number of connections in the symbolic representation of two-step arithmetic problems

En este trabajo identificamos una variable lingüística en los problemas aritméticos verbales de dos pasos, que denominamos “nodo”. Describimos una experiencia con estudiantes de 5º y 6º de primaria (10 y 12 años) cuyo fin fue observar si esta variable lingüística tiene o no influencia significativa en la elección de las operaciones necesarias para solucionar este tipo de problemas. Los resultados obtenidos muestran que el número de nodos en un problema de dos pasos tiene efecto significativo en el proceso de resolución. Esta influencia no se ve alterada por otros factores considerados en este estudio.In this work we identify a new factor in two-steps arithmetic word problems, which we denominate "node” factor. We describe an experience with 5th and 6th grade primary students (11 and 12-year-old pupils) whose purpose was to observe if this factor has or has not significant influence in the election of the necessary operations to solve this type of problems. The obtained results show that the number of nodes in a problem of two steps has significant effect in the resolution process. This significant influence is not altered by other factors considered in this study

Comparing and modeling land use organization in cities

The advent of geolocated ICT technologies opens the possibility of exploring how people use space in cities, bringing an important new tool for urban scientists and planners, especially for regions where data is scarce or not available. Here we apply a functional network approach to determine land use patterns from mobile phone records. The versatility of the method allows us to run a systematic comparison between Spanish cities of various sizes. The method detects four major land use types that correspond to different temporal patterns. The proportion of these types, their spatial organization and scaling show a strong similarity between all cities that breaks down at a very local scale, where land use mixing is specific to each urban area. Finally, we introduce a model inspired by Schelling's segregation, able to explain and reproduce these results with simple interaction rules between different land uses.Comment: 9 pages, 6 figures + Supplementary informatio

Cross-Checking Different Sources of Mobility Information

The pervasive use of new mobile devices has allowed a better characterization in space and time of human concentrations and mobility in general. Besides its theoretical interest, describing mobility is of great importance for a number of practical applications ranging from the forecast of disease spreading to the design of new spaces in urban environments. While classical data sources, such as surveys or census, have a limited level of geographical resolution (e.g., districts, municipalities, counties are typically used) or are restricted to generic workdays or weekends, the data coming from mobile devices can be precisely located both in time and space. Most previous works have used a single data source to study human mobility patterns. Here we perform instead a cross-check analysis by comparing results obtained with data collected from three different sources: Twitter, census, and cell phones. The analysis is focused on the urban areas of Barcelona and Madrid, for which data of the three types is available. We assess the correlation between the datasets on different aspects: the spatial distribution of people concentration, the temporal evolution of people density, and the mobility patterns of individuals. Our results show that the three data sources are providing comparable information. Even though the representativeness of Twitter geolocated data is lower than that of mobile phone and census data, the correlations between the population density profiles and mobility patterns detected by the three datasets are close to one in a grid with cells of 2×2 and 1×1 square kilometers. This level of correlation supports the feasibility of interchanging the three data sources at the spatio-temporal scales considered.Partial financial support has been received from the Spanish Ministry of Economy (MINECO) and FEDER (EU) under projects MODASS (FIS2011-24785) and INTENSE@COSYP (FIS2012-30634), and from the EU Commission through projects EUNOIA, LASAGNE and INSIGHT. ML acknowledges funding from the Conselleria d'Educació, Cultura i Universitats of the Government of the Balearic Islands, and JJR from the Ramón y Cajal program of MINECO.Peer Reviewe

YouTube y la economía del algoritmo

YouTube navega entre aguas revueltas pese a la solidez de la marca y de su altísimo consumo. Siendo la segunda página web más visitada del mundo según el índice Alexa, sólo tras el buscador de Google –propietaria de la plataforma de vídeo, además-, los nuevos competidores del vídeo online han creado un escenario de fuerte rivalidad en la que conviven diferentes modelos de negocio, contenedores de productos muy diversos, con una más que evidente identidad mutante. A YouTube se le suponía un modelo definido y una identidad consolidada: era el espacio en el que los usuarios compartían sus vídeos de manera más o menos altruista, donde las discográficas rompían los records de reproducciones con las estrellas de moda y con vídeo-eventos viralizados por sorpresa como Gangnam Style o Despacito, o donde los usuarios seguían vídeo-tutoriales o unboxings de los temas más diversos. Sin embargo, desde el momento en que la plataforma de vídeo de Google comenzó a incentivar la producción de sus usuarios más seguidos a través del patrocinio (mediante el programa de Partners) y, con más fuerza, cuando YouTube empezó a producir contenidos propios, evidenció que los vídeos virales de gatitos, los tutoriales de maquillaje y los clips de intérpretes emergentes del k-pop eran insuficientes para sostener una inversión que se adivina multimillonaria. YouTube no quiere quedarse atrás en la batalla de las OTTs comerciales y se reivindica como marca consolidada capaz de lograr el compromiso de sus clientes a través del pago de una cuota

Small bowel enteroscopy - A joint clinical guideline from the spanish and portuguese small bowel study groups

The present evidence-based guidelines are focused on the use of device-assisted enteroscopy in the management of small-bowel diseases. A panel of experts selected by the Spanish and Portuguese small bowel study groups reviewed the available evidence focusing on the main indications of this technique, its role in the management algorithm of each indication and on its diagnostic and therapeutic yields. A set of recommendations were issued accordingly.Estas recomendações baseadas na evidência detalham o uso da enteroscopia assistida por dispositivo no manejo clínico das doenças do intestino delgado. Um conjunto de Gastrenterologistas diferenciados em patologia do intestino delgado foi selecionado pelos grupos de estudos Espanhol e Português de intestino delgado para rever a evidência disponível sobre as principais indicações desta técnica, o seu papel nos algoritmos de manejo de cada indicação e sobre o seu rendimento diagnóstico e terapêutico. Foi gerado um conjunto de recomendações pelos autores

Exploring the potential of phone call data to characterize the relationship between social network and travel behavior

[EN] Social network contacts have significant influence on individual travel behavior. However, transport models rarely consider social interaction. One of the reasons is the difficulty to properly model social influence based on the limited data available. Non-conventional, passively collected data sources, such as Twitter, Facebook or mobile phones, provide large amounts of data containing both social interaction and spatiotemporal information. The analysis of such data opens an opportunity to better understand the influence of social networks on travel behavior. The main objective of this paper is to examine the relationship between travel behavior and social networks using mobile phone data. A huge dataset containing billions of registers has been used for this study. The paper analyzes the nature of co-location events and frequent locations shared by social network contacts, aiming not only to provide understanding on why users share certain locations, but also to quantify the degree in which the different types of locations are shared. Locations have been classified as frequent (home, work and other) and non-frequent. A novel approach to identify co-location events based on the intersection of users' mobility models has been proposed. Results show that other locations different from home and work are frequently associated to social interaction. Additionally, the importance of non-frequent locations in co-location events is shown. Finally, the potential application of the data analysis results to improve activity-based transport models and assess transport policies is discussed.The authors would like to thank the anonymous reviewers for their valuable comments and suggestions to improve the quality of the paper. The research leading to these results has received funding from the European Union Seventh Framework Programme FP7/2007-2013 under grant agreement no 318367 (EUNOIA project) and no 611307 (INSIGHT project). The work of ML has been funded under the PD/004/2013 project, from the Conselleria de Educacion, Cultura y Universidades of the Government of the Balearic Islands and from the European Social Fund through the Balearic Islands ESF operational program for 2013-2017.Picornell Tronch, M.; Ruiz Sánchez, T.; Lenormand, M.; Ramasco, JJ.; Dubernet, T.; Frías-Martínez, E. (2015). Exploring the potential of phone call data to characterize the relationship between social network and travel behavior. Transportation. 42(4):647-668. https://doi.org/10.1007/s11116-015-9594-1S647668424Ahas, R., Aasa, A., Silm, S., Tiru, M.: Daily rhythms of suburban commuters’ movements in the tallinn metropolitan area: case study with mobile positioning data. Transp. Res. 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