BRAIN COMPUTER INTERFACE - Application of an Adaptive Bi-stage Classifier based on RBF-HMM

Brain Computer Interface is an emerging technology that allows new output paths to communicate the users intentions without the use of normal output paths, such as muscles or nerves. In order to obtain their objective, BCI devices make use of classifiers which translate inputs from the users brain signals into commands for external devices. This paper describes an adaptive bi-stage classifier. The first stage is based on Radial Basis Function neural networks, which provides sequences of pre-assignations to the second stage, that it is based on three different Hidden Markov Models, each one trained with pre-assignation sequences from the cognitive activities between classifying. The segment of EEG signal is assigned to the HMMwith the highest probability of generating the pre-assignation sequence. The algorithm is tested with real samples of electroencephalografic signal, from five healthy volunteers using the cross-validation method. The results allow to conclude that it is possible to implement this algorithm in an on-line BCI device. The results also shown the huge dependency of the percentage of the correct classification from the user and the setup parameters of the classifier

Application of sources reconstruction techniques: Theory and practical results.

In this paper, four new applications of sources reconstruction techniques (also called diagnostic techniques) are presented. First of all, the important information of such techniques will be mentioned, seeing that they are a tool to obtain the extremely near field from the measured data. Depending on the region where these data are taken (near field or far field), the reconstruction method will be different. Also, all of them may be classified in other two groups depending on its features: Integral Equation Methods (IEM) or Modal Expansion Methods. Classical applications of such techniques are errors detection, like phase errors in arrays or conformai errors in reflectors, therefore, they constitute an important antenna design tool. But also and it has been said, they can be used as the basis to other applications whose aim is to improve the measurement results in anechoic chambers or non anechoic environments. Here, four of them are presented, being the reflection cancelling, the detection of unwanted radiation points, the truncation error reduction in planar or cylindrical near-field and the noise reduction

Valuing qalys at the end of life

There have been changes in the way that NICE evaluates medical treatments for patients who are in the last stages of their lives. If medicines fulfil some criteria to be considered “end of life” NICE considers if QALYs gained under these circumstances should receive an extra weight. In this paper we provide evidence about the social support that this policy may have. We present the result of three surveys conducted in the Spanish general population (n=813). Survey 1 compared increases in life expectancy for patients at the end of their lives with health gains from temporary health problems. Survey 2 compared health gains for temporary health problems with health gains from end of life palliative care. Survey 3 compared increases in life expectancy with palliative care in both cases for end of life patients. Preferences were elicited with Person Trade-Off and Willingness to pay techniques. Our results suggest that QALYs for end of life treatments have a higher social value than for temporary health problems. However, we also find that people discriminate between different ways of health gains within End of Life treatment. People seem to attach a greater weight to palliative care than to life extension.QALY weights, end of life, palliative care, life extension

Prevalencia de anomalias dentomaxilares y necesidad de tratamiento ortodoncico en ninos de 12 anos de edad en colegios municipalizados de la Comuna de Talca 2007

68 p.Se realizó un estudio de tipo observacional descriptivo de prevalencia de anomalías dentomaxilares en la población de 12 años de los colegios municipalizados de la comuna de Talca, en el año 2007. El estudio consistió en un examen clínico, en colegios municipalizados de la ciudad de Talca. Para ser parte del estudio clínico se realizó autorización al los encargados de cada colegio, se les informó en que consistía el estudio y en caso de de encontrar cualquier información relevante se les informaría a los padres. Se examinaron clínicamente a 187 pacientes, y la información obtenida se traspaso a una ficha, el la cual se aplicaba el criterio de necesidad de tratamiento del DAI con el anexo de la relación molar y canina. Del total de pacientes, el 57% fueron de sexo masculino y el 43% fueron de sexo femenino. El resultado de este examen clínico para la necesidad de tratamiento fue que un 51,8% de la población total de 12 años presenta una anomalía dentoamaxilar con necesidad de tratamiento y un 48.2% presenta una oclusión normal o una maloclusión mínima sin necesidad de tratamiento. Dentro de las categorías del índice DAI, existe un 48,1% de población que no presenta maloclusión o presenta una maloclusión mínima, un 23,5% que presenta una maloclusión definitiva, un 12,8% que presenta una maloclusión severa y un 15,5% maloclusión discapacitante, no existiendo una diferencia significativa en las primeras 3 categorías, pero presentando un mayor porcentaje en el sexo masculino en la maloclusión discapacitante. En cuanto a la clasificación de Angle, se presentó un 52% de la población con Clase I y un 24% presentó con Clase II y Clase III, no se presentó una diferencia significativa entre el sexo masculino y el femenino en las 2 primeras clases, pero si se existe un mayor porcentaje de población clase III masculina (64,4%) en relación a la femenina (35,6%)

La alternativa deber/deber de + infinitivo en el siglo XVI. Factores condicionantes en un fenómeno de variación sintáctica a partir de un corpus epistolar

Este estudio parte de la sorprendente falta de atención concedida por la lingüística hispánica a la explicación de un antiguo fenómeno de variación sintáctica: la alternancia entre perífrasis modales deber/deber de + infinitivo, durante siglos asociada a una oposición rígida entre valores epistémicos y deónticos procedente de la tradición normativa. Aunque algunos trabajos recientes han mostrado su interés por la distribución actual de ambas perífrasis en diferentes comunidades hispánicas, se conoce poco sobre esta variación en el pasado. Este artículo pretende cubrir este vacío mediante un análisis sistemático del contexto variable que rodea a esta variable sintáctica, basándose para ello en los principios y métodos de la lingüística variacionista, aplicados a un extenso corpus de textos epistolares escritos en el siglo XVI, muchos de ellos de carácter privado. Los datos de esta investigación señalan la influencia positiva no solo de ciertos contextos lingüísticos (pasado simple, modalidad epistémica, contextos de intensificación, enunciados negativos) y estilísticos (cartas privadas y relación cercana entre los interlocutores) en la variación, sino también la existencia de algunas interacciones relevantes entre esos factores. En síntesis, los resultados del estudio muestran la importante influencia de diferentes elementos de modalización –y no solo la tradicional dicotomía deóntico-epistémico– en el perfil variacionista de estas perífrasis modales en el español clásico.This study arises from the surprising lack of attention given by the Spanish linguistics to explain an old fact of syntactic variation: the alternation between modal periphrasis deber/deber de + infinitive, for several centuries associated to a rigid opposition between epistemic and deontic values in the normative tradition. Although certain studies have focused recently on the current distribution of both periphrasis in different Hispanic communities, very little is known about this variation in the past. This research aims to address this gap through systematic and comprehensive analysis of this variable context, based on the principles and methods of linguistic variationism applied to a large corpus of epistolary texts written in the sixteenth century, many of them of private nature. Actually, the results of the study highlight the positive influence not only of certain linguistic (past simple, epistemic modality, intensified statements, negative sentences) and stylistic contexts (private letters and close relationship between the interlocutors), but even more decisive, the interactions between these factors. The results of the study show the important influence of different structural and non structural elements of modalization –and not only the traditional deontic-epistemic dichotomy- in the variationist profile of these modal periphrasis in classical Spanish

Transforming YouTube into a valid source of knowledge for Anatomy students

[EN] YouTube is a free and easily accessible tool, with growing importance in the teaching field due to the content of the videos and their interaction options through comments, responses and insertion in social networks. However, some limitations can reduce the value of this tool in University teaching if institutional control is not carried out. Our project consists of the search for experiences based on learning Anatomy on YouTube to be able to incorporate this tool in our department. Almost all researchers found that most of students use YouTube as a source of anatomical knowledge, despite limitations and criticism based on ethical and privacy issues, the video experience itself, the YouTube search algorithm, lack of quality control, advertising purposes or excessive video offer. Researchers experienced that most of the available videos had a poor quality and many mistakes, so professors must be involved in the search and selection of the best appropriate videos. We conclude that YouTube can be used as a source of knowledge for anatomical learning. However it is necessary to inform students of the inconveniences and risks, and make a critical selection by the professors of the videos that best fit in the teaching program.Alegre-Martínez, A.; Martínez-Martínez, MI.; Alfonso-Sánchez, JL. (2020). Transforming YouTube into a valid source of knowledge for Anatomy students. En 6th International Conference on Higher Education Advances (HEAd'20). Editorial Universitat Politècnica de València. (30-05-2020):293-300. https://doi.org/10.4995/HEAd20.2020.11044OCS29330030-05-202

Brain Computer Interface. Comparison of Neural Networks Classifiers.

Brain Computer Interface is an emerging technology that allows new output paths to communicate the user’s intentions without use of normal output ways, such as muscles or nerves (Wolpaw, J. R.; et al., 2002).In order to obtain its objective BCI devices shall make use of classifier which translate the inputs provided by user’s brain signal to commands for external devices. The primary uses of this technology will benefit persons with some kind blocking disease as for example: ALS, brainstem stroke, severe cerebral palsy (Donchin et al., 2000).This report describes three different classifiers based on three different types of neural networks: Radial Basis Functions RBF, Probabilistic Neural Networks PNN, and Multi-Layer Perceptions MLP. The report compares the results produced by them in order to obtain conclusions to apply to an on-line BCI device; it also describes the experimental procedure followed in the experiments. As result of the tests carried out on five healthy volunteers an estimation of the success rate for each type of classifier, the type and architecture of the classifier, and filtering windows are established

Qué tengo que/de hazer?": variación y cambio lingüístico en el seno de las perífrasis de infinitivo a partir de textos escritos de impronta oral en el español clásico

Based on a corpus of communicative immediacy texts from the sixteenth and seventeenth centuries, written by Spaniards of different social background, in this study we carry out a variationist research in order to analyze the envelope of variation which lies behind the alternation between two infinitive modal periphrases in classical Spanish: tener de and tener que + infinitive. The results show how this morphosyntactic variation, far from being a case of free variation, as sometimes has been maintained, is determined by several factors. Among them some of a linguistic nature stand out (aktionsart, person, time, modality sense, sentential modality), although several regularities in the distribution of data also point out towards the potential influence of some stylistic and dialectal constraints. Moreover, the analysis of the diachronic axis allows us to observe the existence of a relevant change in progress, not only in the gradual replacement of tener de by tener que, but also in the explanatory relevance of certain constraints. Thus, some of the linguistic contexts most frequent in the corpus, such as the present tense, the affirmative sentences and the 3rd person, progressively abandon their association with the more traditional variant (tener de) in favor of tener que as time goes by. This helps to understand how, at the end of the classical period, tener que has already overtaken its old competitor, in a process which will be completed in the centuries to come, leaving tener de to some restricted dialectal uses in modern Spanish

Feedback effect analysis by comparison of discrimination capability of On-line and Off-line experimental procedures based on LDA

This paper analyses the user’s feedback influence in the mental task discrimination capability through the comparison of results obtained from Off-line and On-line Brain Computer Interface experimental procedures. Experiments performed under these two paradigms were carried out by five male volunteers. In order to develop a wearable BCI device only two electrodes in C3 and C4 zones have been used for electroencephalographic signal acquisition. These procedures apply seven different types of preprocessing windows and Linear Discrimination Analysis technique to reduce the dimension of the feature space before the quantification of the discrimination capability between the proposed mental activities. The discrimination capability is quantified through statistical analysis, based on bilateral contrast test, between the population of the LDA transformed feature vectors