Prevalence of enamel defects in primary and permanent teeth in a group of schoolchildren from Granada (Spain)

Objective: The purpose of this study was to determine and compare the prevalence and presentations of develop mental defects of the enamel (DDE) in the primary and permanent dentitions of a group of healthy schoolchildren residing in Granada (Spain). Study D esign: A total of 1,414 healthy schoolchildren were examined using modified DDE criteria for recording enamel defects. Results: The prevalence of DDE of any type was 40.2% in primary dentition and 52% in permanent dentition (p<0.033). Of the 31,820 primary and permanent teeth examined in the study, 699 (4.1%) primary and 1,232 (8.3%) permanent teeth had some form of DDE. Diffuse opacity was the most common type of DDE observed in primary teeth, and de marcated opacity in the permanent teeth. Enamel hypoplasia was the least prevalent defect in both dentition types. Conclusions: The study population showed a high prevalence of DDE in primary as well as in permanent denti tion, reflecting the current increasing trend of this condition, which should be considered as a significant public health proble

A new multi-objective wrapper method for feature selection – Accuracy and stability analysis for BCI

Feature selection is an important step in building classifiers for high-dimensional data problems, such as EEG classification for BCI applications. This paper proposes a new wrapper method for feature selection, based on a multi-objective evolutionary algorithm, where the representation of the individuals or potential solutions, along with the breeding operators and objective functions, have been carefully designed to select a small subset of features that has good generalization capability, trying to avoid the over-fitting problems that wrapper methods usually suffer. A novel feature ranking procedure is also proposed in order to analyze the stability of the proposed wrapper method. Four different classification schemes have been applied within the proposed wrapper method in order to evaluate its accuracy and stability for feature selection on a real motor imagery dataset. Experimental results show that the wrapper method presented in this paper is able to obtain very small subsets of features, which are quite stable and also achieve high classification accuracy, regardless of the classifiers used.Project TIN2015-67020-P (Spanish “Ministerio de Economía y Competitividad”)European Regional Development Funds (ERDF

Unified electrical model for the contact regions of staggered Thin Film Transistors

In this work, we propose an unified compact model, which includes the effects of both source and drain contact regions, to describe the electrical characteristics of staggered thin film transistors (TFTs). The model is based on a generic drift analytical expression that describes the intrinsic channel of the transistor. Despite the distributed two-dimensional nature of the contacts in staggered configurations, two-terminal components are usually preferred to model the source and drain contact regions. In this regard, a model based on versatile simple expressions that describe the current-voltage relations of both contact regions are proposed in this work. These expressions are based on the physics underlying a metal-organic-metal structure. They can be adapted to different transport conditions, such as ohmic, space-charge-limited transport or Schottky-like contacts. This adaptation is controlled with the value of a single parameter that modifies the concavity or convexity of these expressions. The model works together with an evolutionary parameter extraction procedure, presented in a previous work for TFTs with negligible drain contact effects, and adapted here to this proposed model for staggered transistors. The results of the model and the evolutionary procedure have been validated with published experimental data of different TFTs, mostly organic thin film transistors (OTFTs). The model and evolutionary procedure agrees with other procedures tested successfully in the literature which were defined to cope with specific kinds of contacts in the TFTs. In this regard, our model and evolutionary parameter extraction procedure unify these previous procedures.Departamento de Electrónica y Tecnología de Computadore

Versatile model for the contact region of organic thin-film transistors

Please cite this article as: A. Romero, J. González, M.J. Deen, J.A. Jiménez-Tejada, Versatile model for the contact region of organic thin-film transistors, Organic Electronics, (2020), 77, 105523.Contact effects in organic thin film transistors (OTFTs) remain an important problem to be solved in these devices. Therefore, the correct physio-chemical modeling of the contact regions in OTFTs is necessary. In this work, a standard model for the contact region of OTFTs is proposed. It is a versatile model that describes the current-voltage characteristics of different kinds of contacts. It reproduces the behavior of Schottky barrier or space-charge limited contacts. It is a simple unified model since only a single parameter is necessary in order to distinguish between both kinds of contacts. The model is easily integrated in a generic compact model for the current-voltage characteristics of OTFTs. The resulting compact model, used in combination with an evolutionary parameter extraction procedure, allows to extract the intrinsic parameters and the current-voltage curves at the contact of single short-channel transistors. There is no need to use transistors with multiple channel lengths to accurately characterize the contact region or the active channel of the transistor. The model is tested with published experimental data of OTFTs with Schottky barrier or space-charge limited contacts. Finally, the method has been used as a diagnostic tool to analyze how an ammonia sensor reacts to different concentrations of the ammonia gas. Interestingly, alterations in the contact region have been detected when the gas concentration varies, transforming the space-charge limited contact of a pristine OTFT into a Schottky barrier contact under the exposure of gas.This work was supported by projects MAT2016-76892-C3-3-R, TIN2015-67020-P and PGC2018-098813-B-C31 funded by the Spanish Government and “European Regional Development Funds (ERDF)”. This work was also supported by NSERC Green Electronics Network (GreEN), Grant Number NETGP 508526–17

Ingeniería de Computadores en la era del Big Data: Computación de altas prestaciones en clasificación y optimización

Este artículo describe las necesidades que las aplicaciones de la ciencia de datos plantean a las arquitecturas de computador y las consecuencias que comportan en la enseñanza de asignaturas de este ámbito. Como ejemplo, de esta relación entre aplicaciones y arquitectura de computadores se describe la asignatura Computación de Altas Prestaciones en Clasificación y Optimización, impartida en el Máster en Ciencia de Datos e Ingeniería de Computadores de la Universidad de Granada.his paper describes the requi rements that present big data applications demand from computer archit ectures and their consequences in the teaching of subjects in this area. As an example of these relationships between applications and computer architectures, the subject High Performance Computing on Classification and Optimiza tion included in the Master of Data Science and Computer Engineering of the University of Granada (Spain) is described.Universidad de Granada: Departamento de Arquitectura y Tecnología de Computadores; Vicerrectorado para la Garantía de la Calidad

Energy-aware Load Balancing of Parallel Evolutionary Algorithms with Heavy Fitness Functions in Heterogeneous CPU-GPU Architectures

By means of the availability of mechanisms such as Dynamic Voltage and Frequency Scaling (DVFS) and heterogeneous architectures including processors with different power consumption profiles, it is possible to devise scheduling algorithms aware of both runtime and energy consumption in parallel programs. In this paper, we propose and evaluate a multi-objective (more specifically, a bi-objective) approach to distribute the workload among the processing cores in a given heterogeneous parallel CPU-GPU architecture. The aim of this distribution may be either to save energy without increasing the running time or to reach a trade-off among time and energy consumption. The parallel programs considered here are master-worker evolutionary algorithms where the evaluation of the fitness function for the individuals in the population demands the most part of the computing time. As many useful bioinformatics and data mining applications exhibit this kind of parallel profile, the proposed energy-aware approach for workload scheduling could be frequently applied.Spanish Ministerio de Economía y Competitividad under grant TIN2015-67020-PERDF fun

Reflexiones sobre el EEES tras los primeros cursos de la asignatura Arquitectura de Computadores

Han pasado ya algunos cursos académicos desde que empezaron a impartirse en la Universidad de Granada estudios de grado según las directrices del Espacio Europeo de Educación Superior (EEES). En el caso del grado en Ingeniería Informática, este curso 2015/2016 terminará la tercera promoción. En este artículo, tras resumir los objetivos de la denominada reforma de Bolonia, se describen algunas de las situaciones en las que se ha traducido la implementación de la reforma en nuestro país. Para extraer algunas de las conclusiones del artículo se ha tomado como referencia la asignatura de Arquitectura de Computadores de segundo del grado en Ingeniería Informática que está siendo impartida por varios de los autores del artículo.It has been several academic years since the beginning of study programmes at the University of Granada according to the guidelines of the European Higher Education Area. In this paper, after summarizing the main objectives of the so-called Bologna reform, some of the consequences of its implementation in Spain are described. Moreover, the subject of Computer Architecture, taught in the second course by some of the authors of the paper, is considered as a reference to extract some of the conclusions of the paper.Universidad de Granada: Departamento de Arquitectura y Tecnología de Computadores; Vicerrectorado para la Garantía de la Calidad

The Use of Video-Gaming Devices as a Motivation for Learning Embedded Systems Programming

As embedded systems are becoming prevalent in everyday life, many universities are incorporating embedded systems-related courses in their undergraduate curricula. However, it is not easy to motivate students in such courses, since they conceive of embedded systems as bizarre computing elements, different from the personal computers with which they are familiar. This problem has been overcome at the University of Granada, Spain, by taking advantage of the connection many students have with video games.Spanish CICYT Project SAF2010-20558University of Granada Innovative Teaching Project 04-03-0

Motivación para la Ingeniería de Computadores

Los estudios de Ingeniería de Computadores proporcionan competencias que permiten participar en el desarrollo de los actuales y futuros sistemas de cómputo, con una incidencia importante en el entorno socioeconómico, y por tanto con posibilidades profesionales relevantes. Este artículo incluye consideraciones y argumentos para facilitar, a los profesores involucrados en la docencia de asignaturas relacionadas con la Ingeniería de Computadores, la labor de motivación de los estudiantes. En particular se proporcionan algunas estrategias docentes para la motivación y se ilustra su uso en la docencia del lenguaje ensamblador y de los modelos de consistencia de memoria.Computer engineering courses and degrees provide competencies to be involved in the development of present and future computer systems, with a relevant effect in social and economical contexts, and interesting professional opportunities for students. This paper provides some considerations and arguments to make it easier for teachers involved in subjects related with computer engineering topics to motivate their students. More specifically, the use of some motivation strategies for teaching assembly languages and memory consistency models are described.Departamento de Arquitectura y Tecnología de Computadores y Vicerrectorado para la Garantía de la Calidad de la Universidad de Granada

Concepción de un sistema de iluminación inteligente en Smart Cities como Proyecto Fin de Carrera de Ingeniería Informática

Este trabajo presenta el proyecto fin de carrera “Iluminación inteligente en las ciudades del futuro” defendido en Septiembre de 2013 en la titulación Ingeniería Informática de la Universidad de Granada, un proyecto distintivo y que ofrece al alumno una formación y una madurez añadida. Durante el desarrollo de este proyecto se presenta un sistema de gestión de farolas inteligentes basado en lámparas LED, diseñadas para facilitar su despliegue en las instalaciones existentes. El enfoque propuesto, basado en tecnologías de comunicación inalámbrica, permite reducir al mínimo el coste de la inversión de los sistemas de cable tradicionales. Gracias a la realización de este proyecto, se consigue aprender tecnologías y sistemas que no son tratados en la carrera, permitiendo al alumnado conocer uno de los temas más demandados en la actualidad.This paper presents the final project "Intelligent lighting in the cities of the future" presented in September 2013 at the Computer Engineering degree at the University of Granada, a distinctive project that offers students an added training and maturity. During the development of this project a management system based on smart streetlights LED lamps designed for easy deployment inexisting facilities is presented. The proposed approach, based on wireless communication technologies, can minimize the investment cost of traditional cable systems. Thanks to this project, one gets to learn technologies and systems that are not treated in the career, allowing the students to know one of the most popular topics today.Universidad de Granada: Departamento de Arquitectura y Tecnología de Computadores; Vicerrectorado para la Garantía de la Calidad