1,721,283 research outputs found
Portable Bio-Signals Devices for Brain Computer Interface and Long-Term Patient Monitoring
No full textA Novel Approach to Recognize Valvular Heart Diseases Based on Morphological Similarity of Heartbeats in Seismocardiography Signals
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Evaluating time-varying heart-rate variability power spectral density
No full textAn adaptive scheme for the weighted-least-square (WLS) is proposed. Algorithm performance in individuating the tracking the modifications of the cardiac autonomic control is illustrated. To make data interpretation easier, the time-frequency distributions are displayed as spectrograms. Additionally, the signal speed variation is used to draw the attention of the physician to transient episode
Study of the Control Strategy of the Quadriceps Muscles in Anterior Knee Pain
No full textAnterior knee pain (AKP) is a common pathological condition, particularly among young people and athletes, associated to an abnormal motion of the patella during the bending of the knee and possibly dependent on a muscular or structural imbalance. A lack of synergy in the quadriceps muscles results in a dynamic misalignment of the patella, which in turn produces pain. AKP rehabilitative therapy consists of conservative treatment whose main objective is to strengthen the Vastus Medialis. The aim of this article is to study the quadriceps muscle control strategy in AKP patients during an isokinetic exercise. Analysis of the muscle activation strategy is important for an objective measurement of the knee functionality in that it helps to diagnose and monitor the rehabilitative treatment. Surface electromyography (EMG) from the three superficial muscles of the femoral quadriceps during a concentric isokinetic exercise has been analyzed along with the signals of knee joint position and torque. A group of 12 AKP patients has been compared with a group of 30 normal subjects. Analysis of the grand ensemble average of the EMG linear envelopes in AKP patients reveals significant modifications in Vastus Medialis activity compared to the other quadriceps muscles. In order to study the synergy of the muscles, temporal identifiers have been associated to the EMG linear envelopes. To this end, EMG linear envelope decomposition in Gaussian pulses turned out to be effective and the results highlight an appreciable delay in the activation of the Vastus Medialis in AKP patients. This muscular unbalance can explain the abnormal motion of the patella. Anterior knee pain (AKP) is a common pathological condition, particularly among young people and athletes, associated to an abnormal motion of the patella during the bending of the knee and possibly dependent on a muscular or structural imbalance. A lack of synergy in the quadriceps muscles results in a dynamic misalignment of the patella, which in turn produces pain. AKP rehabilitative therapy consists of conservative treatment whose main objective is to strengthen the Vastus Medialis. The aim of this article is to study the quadriceps muscle control strategy in AKP patients during an isokinetic exercise. Analysis of the muscle activation strategy is important for an objective measurement of the knee functionality in that it helps to diagnose and monitor the rehabilitative treatment. Surface electromyography (EMG) from the three superficial muscles of the femoral quadriceps during a concentric isokinetic exercise has been analyzed along with the signals of knee joint position and torque. A group of 12 AKP patients has been compared with a group of 30 normal subjects. Analysis of the grand ensemble average of the EMG linear envelopes in AKP patients reveals significant modifications in Vastus Medialis activity compared to the other quadriceps muscles. In order to study the synergy of the muscles, temporal identifiers have been associated to the EMG linear envelopes. To this end, EMG linear envelope decomposition in Gaussian pulses turned out to be effective and the results highlight an appreciable delay in the activation of the Vastus Medialis in AKP patients. This muscular unbalance can explain the abnormal motion of the patella
HRV Adaptive Spectral Estimation for Transient Detection
No full textQuantitative monitoring of cardiac autonomic control can be provided, non invasively, by of heart rate variability (HRV) analysis. The study of the HRV is finding more and more fields of application. HRV long-term and short-term analysis can be performed. Among the latter, some applications have to deal with relatively brief changes of the simpatho-vagal activity, as, for example, the study of the fetal heart rate (correlated with uterine contractions). Parametric AR spectral estimation is commonly used to analyse the HRV signal association with the power spectrum bands related to simpatho-vagal activities. However, the computation is limited by a compromise between time resolution and stability. This study aims to indicate and to evaluate the performances of a multiple, recursive, time-varying AR identification of HRV power spectral density, which adapts to signal characteristic. This solution provides both synthetic information in stationary periods and accurate signal tracking during transients. An additional information, related to signal variation speed, can be used to provide a recognition of transient episodes. Test signals were used to measure the performance of the adaptive method with respect to the standard spectral estimation. Error analysis confirms the enhanced performances of the adaptive metho
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