Spatial distribution of HD-EMG improves identification of task and force in patients with incomplete spinal cord injury

Background: Recent studies show that spatial distribution of High Density surface EMG maps (HD-EMG) improves the identification of tasks and their corresponding contraction levels. However, in patients with incomplete spinal cord injury (iSCI), some nerves that control muscles are damaged, leaving some muscle parts without an innervation. Therefore, HD-EMG maps in patients with iSCI are affected by the injury and they can be different for every patient. The objective of this study is to investigate the spatial distribution of intensity in HD-EMG recordings to distinguish co-activation patterns for different tasks and effort levels in patients with iSCI. These patterns are evaluated to be used for extraction of motion intention.; Method: HD-EMG was recorded in patients during four isometric tasks of the forearm at three different effort levels. A linear discriminant classifier based on intensity and spatial features of HD-EMG maps of five upper-limb muscles was used to identify the attempted tasks. Task and force identification were evaluated for each patient individually, and the reliability of the identification was tested with respect to muscle fatigue and time interval between training and identification. Results: Three feature sets were analyzed in the identification: 1) intensity of the HD-EMG map, 2) intensity and center of gravity of HD-EMG maps and 3) intensity of a single differential EMG channel (gold standard).; Results show that the combination of intensity and spatial features in classification identifies tasks and effort levels properly (Acc = 98.8 %; S = 92.5 %; P = 93.2 %; SP = 99.4 %) and outperforms significantly the other two feature sets (p < 0.05).; Conclusion: In spite of the limited motor functionality, a specific co-activation pattern for each patient exists for both intensity, and spatial distribution of myoelectric activity. The spatial distribution is less sensitive than intensity to myoelectric changes that occur due to fatigue, and other time-dependent influences.Peer ReviewedPostprint (published version

Prediction of isometric motor tasks and effort levels based on high-density EMG in patients with incomplete spinal cord injury

Objective. The development of modern assistive and rehabilitation devices requires reliable and easy-to-use methods to extract neural information for control of devices. Group-specific pattern recognition identifiers are influenced by inter-subject variability. Based on high-density EMG (HD-EMG) maps, our research group has already shown that inter-subject muscle activation patterns exist in a population of healthy subjects. The aim of this paper is to analyze muscle activation patterns associated with four tasks (flexion/extension of the elbow, and supination/pronation of the forearm) at three different effort levels in a group of patients with incomplete Spinal Cord Injury (iSCI). Approach. Muscle activation patterns were evaluated by the automatic identification of these four isometric tasks along with the identification of levels of voluntary contractions. Two types of classifiers were considered in the identification: linear discriminant analysis and support vector machine. Main results. Results show that performance of classification increases when combining features extracted from intensity and spatial information of HD-EMG maps (accuracy = 97.5%). Moreover, when compared to a population with injuries at different levels, a lower variability between activation maps was obtained within a group of patients with similar injury suggesting stronger task-specific and effort-level-specific co-activation patterns, which enable better prediction results. Significance. Despite the challenge of identifying both the four tasks and the three effort levels in patients with iSCI, promising results were obtained which support the use of HD-EMG features for providing useful information regarding motion and force intentionPeer ReviewedPostprint (author's final draft

GESTION ESTRATEGICA DEL FACTOR INVESTIGACION DEL MODELO DE CALIDAD DEL CONSEJO DE EVALUACIÓN, ACREDITACIÓN Y CERTIFICACIÓN DE LA CALIDAD DE LA EDUCACIÓN SUPERIOR UNIVERSITARIA BAJO EL PARADIGMA DEL CAPITAL INTELECTUAL: CASO UNIVERSIDAD CATOLICA DE SANTA MARIA

A pesar de la importancia de la investigación en el quehacer universitario, no existe un método que permita gestionarla adecuadamente. Por otro lado, existen modelos de calidad, como el del CONEAU, ABET, ANECA, RIEV, etc., los cuales nos muestran estándares que se deben cumplir para acreditar la calidad en investigación, pero no se tiene una metodología que permita cumplir con dichos criterios, el presente trabajo genera un método que permite a partir de un modelo de calidad, considerando el paradigma del capital intelectual, utilizando el quality function deployment (QFD), con ayuda de los docentes y alumnos de la institución generar un eje del mapa estratégico que contemple las acciones requeridas para cumplir los requerimientos del modelo. El método propuesto se ha implementado en la Universidad Católica de Santa María, UCSM. Finalmente se analizan las ventajas del método implementado

On the numerical computation of Diophantine rotation numbers of analytic circle maps

In this paper we present a numerical method to compute Diophantine rotation numbers of circle maps with high accuracy. We mainly focus on analytic circle diffeomorphisms, but the method also works in the case of (enough) finite differentiability. The keystone of the method is that, under these conditions, the map is conjugate to a rigid rotation of the circle. Moreover, albeit it is not fully justified by our construction, the method turns to be quite efficient for computing rational rotation numbers. We discuss the method through several numerical examples

Asymptotic behaviour of the domain of analyticity of invariant curves of the standard map

In this paper we consider the standard map, and we study the invariant curve obtained by analytical continuation, with respect to the perturbative parameter E, of the invariant circle of rotation number the golden mean corresponding to the case E=0. We show that, if we consider the parameterization that conjugates the dynamics of this curve to an irrational rotation, the domain of definition of this conjugation has an asymptotic boundary of analyticity when E->0 (in the sense of the singular perturbation theory). This boundary is obtained studying the conjugation problem for the so-called semi-standard map. To prove this result we have used KAM-like methods adapted to the framework of singular perturbation theory, as well as matching techniques to join di erent pieces of the conjugation, obtained in different parts of its domain of analyticity

Uso de la generación de vapores en la determinación de metales traza por técnicas atómicas

La generación de vapor es una técnica de introducción de muestra que ha sido empleada para incrementar la sensibilidad en la determinación de los elementos que forman hidruros usando diferentes técnicas espectroscópicas como AAS. (Espectroscopía de Absorción Atómica), AFS (Espectroscopía de Fluorescencia Atómica) o ICPOES (Espectroscopía de Emisión Óptica con fuente de Plasma de Acoplamiento Inductivo). En las últimas décadas la aplicación de la generación de vapor se ha ampliado a nuevos elementos que incluyen metales nobles y de transición. A lo largo de esta tesis los diferentes parámetros que influyen en la generación de vapor de metales nobles y de transición han sido estudiados utilizando: dos técnicas espectroscópicas diferentes, el ICPOES y HRCSAAS (Espectroscopía de Absorción Atómica de Alta Resolución con Fuente Continua); distintos sistemas de introducción de muestra desde un separador de salida forzada a sistema duales de introducción de muestra como el MSIS (Multimode Sample Introduction System) y el CMA (Concomitant Metal Analyzer) y diferentes aditivos incluyendo agentes complejantes, surfactantes y líquidos iónicos. Esto permitió el desarrollo de distintos métodos de análisis. Por último, se inició la investigación para determinar la naturaleza de los vapores generados

Air pollution: a review of its economic effects and policies to mitigate them

La contaminación atmosférica suscita un interés cada vez mayor entre la comunidad científica, los poderes públicos y la población en general, lo que ha llevado a un fuerte aumento en el número de artículos científicos sobre este asunto. Este documento proporciona un resumen de la literatura económica reciente más destacada sobre los efectos de la contaminación atmosférica, las principales lecciones de política que se pueden extraer de ella y las áreas en las que sería especialmente valioso centrar los esfuerzos de investigación. La literatura ha encontrado efectos negativos considerables de la contaminación del aire sobre la salud y la esperanza de vida. También hay alguna evidencia de que la contaminación del aire puede tener efectos negativos no relacionados con la salud, reduciendo la oferta laboral y la productividad, aunque la evidencia no es tan clara en el último aspecto. La literatura también sugiere que los efectos tanto sobre la salud como sobre aspectos no relacionados con ella pueden ser heterogéneos en varias dimensiones; sobre todo respecto a la edad, con efectos más negativos para los más mayores. Finalmente, el documento repasa la literatura sobre las políticas de reducción de la contaminación, como, por ejemplo, zonas de bajas emisiones, reducción de los límites de velocidad o rotación de matrículas. El documento concluye que se necesita más investigación sobre los efectos de las distintas políticas para abordar la contaminación.Air pollution is an increasing cause of concern among the scientific community, policymakers and the general public. This interest has led to a sharp increase in the number of scientific papers on air pollution. This paper provides a summary of the most prominent recent economic literature on the effects of air pollution, the main policy lessons that can be drawn from it, and the areas in which more research would be especially valuable. The literature has found sizable negative effects of air pollution on health and mortality. There is also some evidence that air pollution may have negative non-health effects, reducing labour supply and productivity, although the evidence is more mixed on the latter aspect. The literature also suggests that effects on both health and non-health dimensions may be heterogeneous in a number of dimensions, most prominently age, with more negative effects for the elderly. Finally, more research is needed on which policies to tackle air pollution would be more cost-effective

Transition towards a sustainable mobility in a suburbanising urban area: The case of Barcelona

This article aimsed to address the apparent contradiction between the urban demographic and migratory trends and the transition towards a more sustainable mobility that local and metro-politan governments seek. To that end, it uses the case of Barcelona, and its metropolitan area during the first decades of the 21st century, characterized by suburbanisation and gentrification. Employing demographic, mobility and transport, and air quality statistics, we intended to ana-lyse: a) the spatial demographic trends in the metropolitan area of Barcelona (AMB), particularly regarding the core and periphery population growth or decline; b) trends in daily mobility and how the public and private transport mix has changed; and c) pollution data changes confirming the success or failure of the private vehicle reduction policy. Findings con-firm our initial hypothesis: the slow but steady transition towards sustainable forms of mobility in the core city and the dense contiguous municipalities is counterbalanced by what occurs in the peripheral suburbs. There, the use of private vehicles is still preeminent and growing. Never-theless, the air quality has improved in the most central municipalities of the AMB (for which data are available), even if not all parameters have seen a similar pollution reduction

Influence of metallic artifact filtering on MEG signals for source localization during interictal epileptiform activity

Objective. Medical intractable epilepsy is a common condition that affects 40% of epileptic patients that generally have to undergo resective surgery. Magnetoencephalography (MEG) has been increasingly used to identify the epileptogenic foci through equivalent current dipole (ECD) modeling, one of the most accepted methods to obtain an accurate localization of interictal epileptiform discharges (IEDs). Modeling requires that MEG signals are adequately preprocessed to reduce interferences, a task that has been greatly improved by the use of blind source separation (BSS) methods. MEG recordings are highly sensitive to metallic interferences originated inside the head by implanted intracranial electrodes, dental prosthesis, etc and also coming from external sources such as pacemakers or vagal stimulators. To reduce these artifacts, a BSS-based fully automatic procedure was recently developed and validated, showing an effective reduction of metallic artifacts in simulated and real signals (Migliorelli et al 2015 J. Neural Eng. 12 046001). The main objective of this study was to evaluate its effects in the detection of IEDs and ECD modeling of patients with focal epilepsy and metallic interference. Approach. A comparison between the resulting positions of ECDs was performed: without removing metallic interference; rejecting only channels with large metallic artifacts; and after BSS-based reduction. Measures of dispersion and distance of ECDs were defined to analyze the results. Main results. The relationship between the artifact-to-signal ratio and ECD fitting showed that higher values of metallic interference produced highly scattered dipoles. Results revealed a significant reduction on dispersion using the BSS-based reduction procedure, yielding feasible locations of ECDs in contrast to the other two approaches. Significance. The automatic BSS-based method can be applied to MEG datasets affected by metallic artifacts as a processing step to improve the localization of epileptic foci.Postprint (published version

A didactical proposal: The leather processing. Tools, elaboration and divulgation

El presente trabajo pretende ofrecer una propuesta didáctica que posibilite la difusión del conocimiento científico-histórico que tenemos sobre la Prehistoria de una forma adecuada al público al que va dirigido, utilizando para ello la manufactura del cuero como eje vertebradorThis research pretends to offer a didactical proposal to enable the divulgation of our current scientific-historical knowledge about Prehistory. Our overriding objective will be to adapt that knowledge to the public that is going to receive it, using for that leather processing as key backbon