Tracking-Based Non-Parametric Background-Foreground Classification in a Chromaticity-Gradient Space

This work presents a novel background-foreground classification technique based on adaptive non-parametric kernel estimation in a color-gradient space of components. By combining normalized color components with their gradients, shadows are efficiently suppressed from the results, while the luminance information in the moving objects is preserved. Moreover, a fast multi-region iterative tracking strategy applied over previously detected foreground regions allows to construct a robust foreground modeling, which combined with the background model increases noticeably the quality in the detections. The proposed strategy has been applied to different kind of sequences, obtaining satisfactory results in complex situations such as those given by dynamic backgrounds, illumination changes, shadows and multiple moving objects

Real-time shot detection based on motion analysis and multiple low-level techniques

To index, search, browse and retrieve relevant material, indexes describing the video content are required. Here, a new and fast strategy which allows detecting abrupt and gradual transitions is proposed. A pixel-based analysis is applied to detect abrupt transitions and, in parallel, an edge-based analysis is used to detect gradual transitions. Both analysis are reinforced with a motion analysis in a second step, which significantly simplifies the threshold selection problem while preserving the computational requirements. The main advantage of the proposed system is its ability to work in real time and the experimental results show high recall and precision values

A nonparametric approach to the estimation of lengths and surface areas

The Minkowski content $L_0(G)$ of a body $G\subset{\mathbb{R}}^d$ represents the boundary length (for $d=2$) or the surface area (for $d=3$) of $G$. A method for estimating $L_0(G)$ is proposed. It relies on a nonparametric estimator based on the information provided by a random sample (taken on a rectangle containing $G$) in which we are able to identify whether every point is inside or outside $G$. Some theoretical properties concerning strong consistency, $L_1$-error and convergence rates are obtained. A practical application to a problem of image analysis in cardiology is discussed in some detail. A brief simulation study is provided.Comment: Published at http://dx.doi.org/10.1214/009053606000001532 in the Annals of Statistics (http://www.imstat.org/aos/) by the Institute of Mathematical Statistics (http://www.imstat.org

Kernel bandwidth estimation for moving object detection in non-stabilized cameras

The evolution of the television market is led by 3DTV technology, and this tendency can accelerate during the next years according to expert forecasts. However, 3DTV delivery by broadcast networks is not currently developed enough, and acts as a bottleneck for the complete deployment of the technology. Thus, increasing interest is dedicated to ste-reo 3DTV formats compatible with current HDTV video equipment and infrastructure, as they may greatly encourage 3D acceptance. In this paper, different subsampling schemes for HDTV compatible transmission of both progressive and interlaced stereo 3DTV are studied and compared. The frequency characteristics and preserved frequency content of each scheme are analyzed, and a simple interpolation filter is specially designed. Finally, the advantages and disadvantages of the different schemes and filters are evaluated through quality testing on several progressive and interlaced video sequences

Enhancing writing skills with seventh graders at a public school through online workshops.

Esta investigación acción describe la experiencia llevada a cabo con estudiantes de séptimo grado en el Inglés como una clase de lengua extranjera en un colegio público en Bogotá, Colombia, de 2013 a 2014. El estudio propone la inclusión de un entorno virtual para enseñar Inglés como lengua extranjera a través de la implementación de cinco talleres de escritura en línea que se coloca en la plataforma Edmodo. Los datos fueron recogidos para mostrar cómo la aplicación de esos cinco talleres en línea mejorada estudiantes de séptimo grado para mejorar sus habilidades de escritura, haciendo uso de los enlaces proporcionados, los modelos presentados y el instrucciones paso a paso dadas en cada taller. Esto demuestra que el uso de talleres en línea mejorado las habilidades de escritura de los estudiantes en las primeras etapas. Los talleres en línea participan los estudiantes en un entorno virtual de aprendizaje donde hicieron uso de la tecnología, interactuaron entre sí y con el profesor también.This action research describes the experience carried out with seventh graders in the English as a foreign language classroom at a public school in Bogotá, Colombia, from 2013 to 2014. The study proposes the inclusion of a virtual environment to teach English as a foreign language through the implementation of five online writing workshops which were placed in the platform Edmodo. Data was collected to show how the implementation of those five online workshops enhanced students of seventh grade to improve their writing skills, making use of the links provided, the models presented and the step by step instructions given in each workshop. It shows that the use of online workshops improved students’ writing skills in early stages. The online workshops involved students into a virtual learning environment where they made use of technology, interacted among themselves and with the teacher as well

Textos reproducibles y dinámicos con PythonTeX

En este artículo se describe el proceso de instalación y utilización del paquete PythonTeX en la elaboración de un texto reproducible y dinámico. Se indican los requisitos tecnológicos y el protocolo de su operación a partir de ejemplos en que se realizan operaciones con matrices y se hacen cálculos elementales de estadística descriptiva

Assessment of coercive persuasion: the Scale of Detection of Coercive Persuasion in Group Contexts (EDPC)

Comunicación presentada en las Jornadas Internacionales ICSA 2017 sobre Dinámicas sectarias y radicalizaciónCoercive persuasion refers to the control and manipulation developed by abusive groups, through different aggressive strategies that influence changes in the environment of its members, distorting cognition, altering emotions and generating significant psychosocial damage. It is a subtle, gradual and powerful force that affects around 500,000 Spanish victims of cultic groups (Cuevas & Perlado, 2011; Cuevas, 2012). Attaining power is one of the main goals of these groups, being the control and exploitation of the individual a part of the process. This derives to individuals giving up their own goals, freedom, material possessions, family and social networks, health or even life itself (Rodríguez-Carballeira, Saldaña, Almendros, Martin-Peña, Escartín, & Porrúa-Garcia, 2015). Such strategies are often implemented in a planned, graduate way and using deceit, difficulting that people who targeted are able to detect their evident aggressiveness and the generated damage. If there is an obvious shortage of instruments measuring psychological abuse in different fields (partner violence, harassment, bullying, etc.), the development of tools to assess the presence of such strategies in group contexts is even more scarce (Almendros, Gámez-Guadix, Carrobles & Rodríguez Carballeira, 2011). One of those assessment tools, the Interview for Detection of Coercive Persuasion (Cuevas & Canto, 2006) contains a wide range of coercive and abusive practises taking place within manipulative group. It has been applied in Spain in the forensic field in prosecutions of abusive groups (Dharma Tradición, Casa Yoga, Miguelianos, Revelance, etc.). The main objective of this recently validated tool (Cuevas, 2016) was to identify and provide evidences of the systematic application of coercive persuasion techniques on victims of abusive groups (Cuevas, 2012, 2016). Deriving from this instrument, sharing objectives, a new scale of 40 items and validated in Spanish population: the Scale of Detection of Coercive Persuasion in Group Contexts, or EDPC (Cuevas, 2016 ). To validate the EDPC, a Spanish sample of 134 people who identified themselves as having been abused or having been overly controlled by a group was selected. To assess criterion validity of the instrument, other different instruments (BSI MOS-SSS, RSE, SLEQ, ICP and EDS) were used. The group psychological abuse scale GPA (Chambers, Langone, Dole, & Grice, 1994), Spanish modified version (Almendros et al.,2004; Almendros et al., 2009) was used to assess the convergent validity of the instrument. The EDPC showed appropriate psychometric properties. In respect to reliability, the standardized Cronbach alpha coefficient reached a value of 0.97. The exploratory factorial analysis indicated the presence of a factor (coercive persuasion), establishing the suitability of a one-dimensional model. This scale aims to be useful in clinical and forensic fields, in order to assess the control and manipulation exercised in group contexts. Using it could be relevant to provide evidences of coercive groups practises, helping at trying to determinate the relationship between damage on the victims and the specific actions taken by groups or individuals who perform the abusive behaviors.Universidad de Málaga. Campus de Excelencia Internacional Andalucía Tech

Contributing to VRPN with a new server for haptic devices (ext. version)

This article is an extended version of the poster paper: Cuevas-Rodriguez, M., Gonzalez-Toledo D., Molina-Tanco, L., Reyes-Lecuona A., 2015, November. “Contributing to VRPN with a new server for haptic devices”. In Proceedings of the ACM symposium on Virtual reality software and technology. ACM.http://dx.doi.org/10.1145/2821592.2821639VRPN is a middleware to access Virtual Reality peripherals. VRPN standard distribution supports Geomagic® (formerly Phantom) haptic devices through the now superseded GHOST library. This paper presents VRPN OpenHaptics Server, a contribution to VRPN library that fully reimplements VRPN support of Geomagic Haptic Devices. The implementation is based on the OpenHaptics v3.0 HLAPI layer, which supports all Geomagic Haptic Devices. We present the architecture of the contributed server, a detailed description of the offered API and an analysis of its performance in a set of example scenarios.Universidad de Málaga. Campus de Excelencia Internacional Andalucía Tech

Interplay Between Yu-Shiba-Rusinov States and Multiple Andreev Reflections

Motivated by recent scanning tunneling microscopy experiments on single magnetic impurities on superconducting surfaces, we present here a comprehensive theoretical study of the interplay between Yu-Shiba-Rusinov bound states and (multiple) Andreev reflections. Our theory is based on a combination of an Anderson model with broken spin degeneracy and nonequilibrium Green's function techniques that allows us to describe the electronic transport through a magnetic impurity coupled to superconducting leads for arbitrary junction transparency. Using this combination we are able to elucidate the different tunneling processes that give a significant contribution to the subgap transport. In particular, we predict the occurrence of a large variety of Andreev reflections mediated by Yu-Shiba-Rusinov bound states that clearly differ from the standard Andreev processes in non-magnetic systems. Moreover, we provide concrete guidelines on how to experimentally identify the subgap features originating from these tunneling events. Overall, our work provides new insight into the role of the spin degree of freedom in Andreev transport physics.Comment: 15 pages, 10 figure