1,721,006 research outputs found
Estimating motor unit discharge pattern from the surface electromyogram
Full text linkUdgivelsesdato: MA
Going Beyond Counting First Authors in Author Co-citation Analysis
Full text linkThe present study examines one of the fundamental aspects of author co-citation analysis (ACA) - the way co-citation
counts are defined. Co-citation counting provides the data on which all subsequent statistical analyses and mappings
are based, and we compare ACA results based on two different types of co-citation counting - the traditional type that
only counts the first one among a cited work's authors on the one hand and a non-traditional type that takes into
account the first 5 authors of a cited work on the other hand. Results indicate that the picture produced through this non-traditional author co-citation counting contains more coherent author groups and is therefore considerably clearer. However, this picture represents fewer specialties in the research field being studied than that produced through the traditional first-author co-citation counting when the same number of top-ranked authors is selected and analyzed. Reasons for these effects are discussed
GPU-based key-frame selection of pulmonary ultrasound images to detect COVID-19
No full textIn the last decades, technological advances have led to a considerable increase in computing power constraints to simulate complex phenomena in various application fields, among which are climate, physics, genomics and medical diagnosis. Often, accurate results in real time, or quasi real time, are needed, especially if related to a process requiring rapid interventions. To deal with such demands, more sophisticated approaches have been designed, including GPUs, multicore processors and hardware accelerators. Supercomputers manage high amounts of data at a very high speed; however, despite their considerable performance, their limitations are due to maintenance costs, rapid obsolescence and notable energy consumption. New processing architectures and GPUs in the medical field can provide diagnostic and therapeutic support whenever the patient is subject to risk. In this context, image processing as an aid to diagnosis, in particular pulmonary ultrasound to detect COVID-19, represents a promising diagnostic tool with the ability to discriminate between different degrees of disease. This technique has several advantages, such as no radiation exposure, low costs, the availability of follow-up tests and the ease of use even with limited resources. This work aims to identify the best approach to optimize and parallelize the selection of the most significant frames of a video which is given as the input to the classification network that will differentiate between healthy and COVID patients. Three approaches have been evaluated: histogram, entropy and ResNet-50, followed by a K-means clustering. Results highlight the third approach as the most accurate, simultaneously showing GPUs significantly lowering all processing times
Comparison of chairs based on HDsEMG of back muscles, biomechanical and comfort indices, for violin and viola players: A short-term study
No full textThis work investigates the effect of different seats on violin and viola players sitting postures using High-Density-surface-Electromyography techniques (HDsEMG), biomechanical and comfort indices. Five types of chairs were assessed on 18 violin and three viola players by comparing: (a) pelvic tilt and kyphosis and lordosis angles, (b) subjective comfort indices, and (c) EMG amplitude of erector spinae and trapezius. Sitting “as you like” on a standard orchestra chair is the condition with the highest subjective comfort (but not significantly different from other chairs). A saddle chair with low back support is associated to the lowest EMG of the erector spinae (p < 0.05) and a saddle stool is associated to the spinal angles closest to those of the standing posture. In 12 out of 21 (57%) musicians, the erector spinae was activated in an intermittent manner, regardless of the chair used. These findings justify further research on the selected chairs, on muscle fatigue and on the intermittent postural control strategy
Design and Characterization of a Textile Electrode System for the Detection of High-Density sEMG
Full text linkMuscle activity monitoring in dynamic conditions is a crucial need in different scenarios, ranging from sport to rehabilitation science and applied physiology. The acquisition of surface electromyographic (sEMG) signals by means of grids of electrodes (High-Density sEMG, HD-sEMG) allows obtaining relevant information on muscle function and recruitment strategies. During dynamic conditions, this possibility demands both a wearable and miniaturized acquisition system and a system of electrodes easy to wear, assuring a stable electrode-skin interface. While recent advancements have been made on the former issue, detection systems specifically designed for dynamic conditions are at best incipient. The aim of this work is to design, characterize, and test a wearable, HD-sEMG detection system based on textile technology. A 32-electrodes, 15 mm inter-electrode distance textile grid was designed and prototyped. The electrical properties of the material constituting the detection system and of the electrode-skin interface were characterized. The quality of sEMG signals was assessed in both static and dynamic contractions. The performance of the textile detection system was comparable to that of conventional systems in terms of stability of the traces, properties of the electrode-skin interface and quality of the collected sEMG signals during quasi-isometric and highly dynamic tasks
Does the amplitude of biceps brachii M waves increase similarly in both limbs during staircase, electrically elicited contractions?
No full textObjective: Humans usually tend to control more finely muscle force production in dominant than non-dominant upper limbs. It is well established that motor unit recruitment is a key mechanism by which muscle force is controlled, and we hypothesized that a relatively smaller number of motor units may be recruited in muscles of dominant than non-dominant limbs for any given increase in synaptic input. Hence, we investigated peripheral properties of dominant and non-dominant biceps brachii through the analysis of M-wave responses to incremental electrical stimulation. Approach: Current pulses at progressively greater intensities were applied in the proximal region of biceps brachii of 16 subjects while surface electromyograms were recorded with a grid of electrodes in the distal region. M-wave amplitude was averaged across channels and normalized with respect to the maximum amplitude value, separately for each stimulation intensity and limb. Amplitude-current intensity curves were interpolated to provide an equal number of stimulation levels between limbs. Differences between dominant and non-dominant arms were assessed through the average increase in M-wave amplitude for consecutive stimulation intensities (increments). Main results: Wilcoxon's signed-rank test showed that increments in the M-wave amplitude were significantly smaller (p = 0.017) in dominant than non-dominant biceps brachii. Significance: The results suggest that there was a more gradual recruitment of motor units in biceps brachii of dominant than non-dominant arms. This is in agreement with the hypothesis of a broader spectrum of motor unit recruitment thresholds in the dominant arm, which may contribute to a finer regulation of force production
Variations on the Author
Full text link“Variations on the Author” discusses two of Eduardo Coutinho’s recent films (Um Dia na Vida, from 2010, and Últimas Conversas, posthumously released in 2015) and their contribution to the general question of documentary authorship. The director’s filmography is characterized by a consistent yet self-effacing form of authorial self-inscription: Coutinho often features as an interviewer that rather than express opinions propels discourses; an interviewer that is good at listening. This mode of self-inscription characterizes him as an author who is not expressive but who is nonetheless markedly present on the screen. In Um Dia na Vida, however, Coutinho is completely absent form the image, while Últimas Conversas, on the contrary, includes a confessional prologue that moves the director from the margins to the center of his films. This article examines the ways in which these works stand out in the filmography of a director who offers new insights into the notion of cinematic authorship
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