Lower Approximations by Fuzzy Consequence Operators

Peer ReviewedPostprint (author's final draft

Huge reduction of defibrillation thresholds using four electrode defibrillators

In the absence of a better solution, ventricular fibril- lation is treated by applying one or several large electri- cal shocks to the patient. The question of how to lower the energy required for a successful shock is still a cur- rent issue in both fundamental research and clinical prac- tice. In the study presented here we will compare defib- rillation applied through a four electrode device with the standard procedure using two electrodes. The method is tested through intensive numerical simulations. Here we have used a one dimensional geometry. At the level of the cardiac tissue, the bidomain and the modified Beeler- Reuter models were used. Three different shock waveforms are tested: monophasic and two types of biphasic shocks. The results are compared with those obtained with stan- dard two electrode device. A significant reduction in de- fibrillation thresholds is achieved for all the three tested waveforms when we use a four electrode device.Postprint (published version

Huge reduction of defibrillation thresholds using four electrode defibrillators

In the absence of a better solution, ventricular fibrillation is treated by applying one or several large electrical shocks to the patient. The question of how to lower the energy required for a successful shock is still a current issue in both fundamental research and clinical practice. In the study presented here we will compare defibrillation applied through a four electrode device with the standard procedure using two electrodes. The method is tested through intensive numerical simulations. Here we have used a one dimensional geometry. At the level of the cardiac tissue, the bidomain and the modified Beeler-Reuter models were used. Three different shock waveforms are tested: monophasic and two types of biphasic shocks. The results are compared with those obtained with standard two electrode device. A significant reduction in defibrillation thresholds is achieved for all the three tested waveforms when we use a four electrode device.Postprint (published version

Influence of gap junction dynamics on the stability of reentrant waves in cadiac tissue

Constant conductances are often assumed when model- ing cardiac tissue. However experimental evidences have shown that gap junctions (GJ) actually connect adjacent cardiac myocytes. These GJ are complex proteins of the connexin family (Cx40; Cx43; Cx45 are the most common in human). These GJ modify the conductances between cardiac cell through a dynamical process. The aim of this study is to develop a bidomain model of the cardiac tis- sue where the dynamics of the connexins is also included. In particular we will compare the differences associated with the use of a monodomain versus bidomain formula- tion in inducing intra-cellular conductance variations. We have found that the monodomain formulation gives con- ductance variations a factor four to five larger with respect to the bidomain formulationPeer ReviewedPostprint (published version

Some illustrative examples of permutability of fuzzy operators and fuzzy relations

Composition of fuzzy operators often appears and it is natural to ask when the order of composition does not change the result. In previous papers, we characterized permutability in the case of fuzzy consequence operators and fuzzy interior operators. We also showed the connection between the permutability of the fuzzy relations and the permutability of their induced fuzzy operators. In this work we present some examples of permutability and non permutability of fuzzy operators and fuzzy relations in order to illustrate these results

On the relation between fuzzy closing morphological operators, fuzzy consequence operators induced by fuzzy preorders and fuzzy closure and co-closure systems

In a previous paper, Elorza and Burillo explored the coherence property in fuzzy consequence operators. In this paper we show that fuzzy closing operators of mathematical morphology are always coherent operators. We also show that the coherence property is the key to link the four following families: fuzzy closing morphological operators, fuzzy consequence operators, fuzzy preorders and fuzzy closure and co-closure systems. This will allow to translate important well-known properties from the field of approximate reasoning to the field of image processing

El trabajo cooperativo y la co-docencia como respuestas metodológicas a las necesidades educativas actuales

El siglo XXI trae consigo distintos cambios sociales, el aumento de la interdependencia global, del número de sistemas democráticos, la necesidad de empresarios creativos o la importancia de las relaciones interpersonales. Los centros educativos están encargados de formar a los jóvenes según las necesidades actuales de la sociedad. No obstante, a pesar de los cambios sociales producidos en los últimos años, las metodologías educativas evolucionan a un ritmo más lento; teniendo el profesor todavía demasiado protagonismo en el aula, centrando el aprendizaje fuera del alumno y convirtiendo las sesiones escolares en lecciones magistrales donde los alumnos actúan como meros oyentes. Ante esta necesidad de adaptar las técnicas de enseñanza a las características sociales actuales surgen diferentes innovaciones educativas, como el aprendizaje cooperativo, la co-docencia o las actividades dentro del marco de la Enseñanza para la Comprensión. No obstante, el surgimiento de estas innovaciones trae consigo interesantes preguntas como ¿Toda innovación educativa es eficaz independientemente de la asignatura, curso o grupo de alumnos? o como ¿Qué beneficios conlleva el uso de cada una de las distintas metodologías educativas? Se sabe que todas las técnicas de enseñanza tienen tanto sus ventajas como inconvenientes, además existen una gran cantidad de estudios previos acerca del uso de todas estas en diversas asignaturas y cursos de índole completamente distinta, cultural y académica. Para intentar confirmar la utilidad de estas metodologías educativas, el objetivo principal de este Trabajo Fin de Máster fue la comprobación empírica de cada una de estas técnicas de enseñanza. Para ello, se estudiaron distintos patrones, como el tiempo activo del profesorado y del alumnado o el número de participaciones de estos, en distintos cursos escolares en las que estuvieran presentes todos los tipos de metodologías educativas. Inicialmente, los resultados mostraron que las nuevas técnicas de enseñanza, el aprendizaje cooperativo y la co-docencia, aumentaban el tiempo de trabajo activo de los alumnos y reducían el tiempo de espera en las cuestiones realizadas al profesor. Resultó interesante observar como las metodologías activas forzaban a una mayor participación por parte del alumnado y que además traían consigo un alto grado de satisfacción, que permitía así mejorar las calificaciones de los alumnos, principalmente de aquellos que tenían notas bajas. No obstante, los resultados mostraron como en función del contenido de la sesión se puede utilizar una u otra metodología educativa. VIII Todo ello nos permite concluir que las metodologías educativas no son excluyentes entre sí y no se limitan a un curso o asignatura. Además, todo indica a que el trabajo cooperativo permite una participación mayor del alumnado y obliga a que estos estén un mayor tiempo activos, por otro lado, la co-docencia permite una atención más personal y de mayor rapidez. Las innovaciones educativas deberían ser tenidas en cuenta seriamente como respuesta a las necesidades de la sociedad actual.The 21st century brings with its different social changes, the increase in global interdependence , the number of democratic systems, the need for creative entrepreneurs or the importance of interpersonal relationships. The educational centers oversee traini ng young people according to the current needs of society. However, despite the social changes p roduced in recent years, educational methodologies are evolving at a slower pace; having the teacher still too much prominence in the classroom, focusing the le arning outside the student and turning the school sessions into lectures where the students act as mere listeners. Faced with this need to adapt teaching techniques to current social characteristics, different educational innovations arise, such as coopera tive learning, co - teaching or activities within the framework of the Teaching for Understanding. However, the emergence of these innovations brings interesting questions such as: Is every educational innovation effective regardless of the subject, course o r group of students? or as What benefits does the use of each of the different educational metho dologies entail? It is known that all teaching techniques have both advantages and disadvantages, in addition there are a lot of previous studies about the use of all these in various subjects and courses of completely different cultural and academic natur e. To try to confirm the usefulness of these educational methodologies, the main objective of this Final Master's Project was the empirical verification of each of these teaching techniques. To do this, different patterns were studied, such as the active t ime of teachers and students or the number of participations of these, in different school courses in which all types of educational methodologies were present. Initially, the results showed that the new teaching techniques, cooperative learning and co - te aching, increased the active work time of the students and reduced the waiting time in the questions made to the teacher. Interestingly, it was also possible to observe how active methodologies forced a greater participation on the part of the students and that they also brought with them a high level of satisfaction, which allowed improving the qualifications of the students, mainly those who had lower grades. H owever, the results showed how, depending on the content of the session, one or another educatio nal methodology can be used. All this allows us to conclude that educational methodologies are not mutually exclusive and are not limited to a course or subjec t. In addition, everything indicates that X cooperative work allows a greater participation of stu dents and requires that they are more active, on the other hand, co - teaching allows more personal attention and faster. Educational innovations should be taken seriously as a response to the needs of today's society

Influence of gap junction dynamics on the stability of reentrant waves in cardiac tissue

Constant conductances are often assumed when model- ing cardiac tissue. However experimental evidences have shown that gap junctions (GJ) actually connect adjacent cardiac myocytes. These GJ are complex proteins of the connexin family (Cx40; Cx43; Cx45 are the most common in human). These GJ modify the conductances between cardiac cell through a dynamical process. The aim of this study is to develop a bidomain model of the cardiac tis- sue where the dynamics of the connexins is also included. In particular we will compare the differences associated with the use of a monodomain versus bidomain formula- tion in inducing intra-cellular conductance variations. We have found that the monodomain formulation gives con- ductance variations a factor four to five larger with respect to the bidomain formulation.Peer ReviewedPostprint (published version

Aging of ECG characteristics over a five year period

The aim of this work was to find evidence of aging of ECG indicators in a population of young adults (52 subjects of age 19 ± 0.6 in 2002). For this purpose, an application which analyzes ECG signals was designed and implemented. The data consist in four different series for each subject of the studied population. Two ECG signals of 5 minute duration (one at rest and one after a mild effort) were taken in 2002 and the exact same procedure was repeated for each subject five years later in 2007. All these electrocardiographic signals were examined by computational techniques in order to extract the RR and QT intervals and the energy content of the T-wave. Next, we have compared all the data using first return maps and measured the data dispersion by evaluating the covariance ellipses. Relations between each of the four data series were studied. The analysis also included the gender and the categorical aspect “practicing sport”