Waveform prototype-based feature learning for automatic detection of the early repolarization pattern in ECG signals

Objective: Our aim was to develop an automated detection method, for prescreening purposes, of early repolarization (ER) pattern with slur/notch configuration in electrocardiogram (ECG) signals using a waveform prototype-based feature vector for supervised classification. Approach: The feature vectors consist of fragments of the ECG signal where the ER pattern is located, instead of abstract descriptive variables of ECG waveforms. The tested classifiers included linear discriminant analysis, k-nearest neighbor algorithm, and support vector machine (SVM). Main results: SVM showed the best performance in Friedman tests in our test data including 5676 subjects representing 45408 leads. Accuracies of the different classifiers showed results well over 90%, indicating that the waveform prototype-based feature vector is an effective representation of the differences between ECG signals with and without the ER pattern. The accuracy of inferior ER was 92.74% and 92.21% for lateral ER. The sensitivity achieved was 91.80% and specificity was 92.73%. Significance: The algorithm presented here showed good performance results, indicating that it could be used as a prescreening tool of ER, and it provides an additional identification of critical cases based on the distances to the classifier decision boundary, which are close to the 0.1 mV threshold and are difficult to label.Peer reviewe

Waveform prototype-based feature learning for automatic detection of the early repolarization pattern in ECG signals

Objective: Our aim was to develop an automated detection method, for prescreening purposes, of early repolarization (ER) pattern with slur/notch configuration in electrocardiogram (ECG) signals using a waveform prototype-based feature vector for supervised classification. Approach: The feature vectors consist of fragments of the ECG signal where the ER pattern is located, instead of abstract descriptive variables of ECG waveforms. The tested classifiers included linear discriminant analysis, k-nearest neighbor algorithm, and support vector machine (SVM). Main results: SVM showed the best performance in Friedman tests in our test data including 5676 subjects representing 45408 leads. Accuracies of the different classifiers showed results well over 90%, indicating that the waveform prototype-based feature vector is an effective representation of the differences between ECG signals with and without the ER pattern. The accuracy of inferior ER was 92.74% and 92.21% for lateral ER. The sensitivity achieved was 91.80% and specificity was 92.73%. Significance: The algorithm presented here showed good performance results, indicating that it could be used as a prescreening tool of ER, and it provides an additional identification of critical cases based on the distances to the classifier decision boundary, which are close to the 0.1 mV threshold and are difficult to label.Peer reviewe

Variation in clutch size in relation to nest size in birds

Peer reviewe

Increasing the capturing angle in print-cam robust watermarking

Abstract It is nowadays more probable that a print media is captured and shared with a mobile phone than with a scanner. The reasons for photographing the print range from intention of copying the image to simply sharing an interesting add with friends. Watermarking offers a solution for carrying side information in the images, and if the watermarking method being used is robust to the print-cam process, the information can be read with a mobile phone camera. In this paper, we present a print-cam robust watermarking method that is also implemented on a mobile phone and evaluated with user tests. Especially, the lens focusing problem when the picture is captured in a wide angle with respect to the printout is addressed. The results show that the method is highly robust to capturing the watermark without errors in angles up to 60° with processing times that are acceptable for real-life applications

Contribution of body movements on the heart rate variability during high intensity running

Abstract We studied the association between the heart rate variability (HRV) and the subject’s movement during high intensity running. HRV is affected by movement, and this phenomena is known as cardiolocomotor coupling (CLC). Characterization of movement related components on the HRV spectrogram is a principal step toward meaningful interpretation of autonomic nervous system (ANS) activity. According to the literature, the aliases of the first and second harmonics of the cadence frequency are the main contributors affecting HRV. Instead, we found out that there is another aliasing component containing significant power in the HRV spectrogram. The source of this component might be the arm swings, torso movement or any other mechanical movement along the horizontal axis, orthogonal to the cadence direction. Our results show that in 13 out of 22 subjects the spectral HRV component arising from the alias of the second harmonic of cadence frequency (vertical acceleration) accommodates significantly less energy than the component related to the alias of the first harmonic of horizontal acceleration. Therefore, neglecting this component and/or considering the second harmonic of the cadence frequency as more dominant one is not always a valid assumption

Bivariate empirical mode decomposition for ECG-based biometric identification with emotional data

Abstract Emotions modulate ECG signals such that they might affect ECG-based biometric identification in real life application. It motivated in finding good feature extraction methods where the emotional state of the subjects has minimum impacts. This paper evaluates feature extraction based on bivariate empirical mode decomposition (BEMD) for biometric identification when emotion is considered. Using the ECG signal from the Mahnob-HCI database for affect recognition, the features were statistical distributions of dominant frequency after applying BEMD analysis to ECG signals. The achieved accuracy was 99.5% with high consistency using kNN classifier in 10-fold cross validation to identify 26 subjects when the emotional states of the subjects were ignored. When the emotional states of the subject were considered, the proposed method also delivered high accuracy, around 99.4%. We concluded that the proposed method offers emotion-independent features for ECG-based biometric identification. The proposed method needs more evaluation related to testing with other classifier and variation in ECG signals, e.g. normal ECG vs. ECG with arrhythmias, ECG from various ages, and ECG from other affective databases

Comparing features from ECG pattern and HRV analysis for emotion recognition system

Abstract We propose new features for emotion recognition from short ECG signals. The features represent the statistical distribution of dominant frequencies, calculated using spectrogram analysis of intrinsic mode function after applying the bivariate empirical mode decomposition to ECG. KNN was used to classify emotions in valence and arousal for a 3-class problem (low-medium-high). Using ECG from the Mahnob-HCI database, the average accuracies for valence and arousal were 55.8% and 59.7% respectively with 10-fold cross validation. The accuracies using features from standard Heart Rate Variability analysis were 42.6% and 47.7% for valence and arousal respectively for the 3-class problem. These features were also tested using subject-independent validation, achieving an accuracy of 59.2% for valence and 58.7% for arousal. The proposed features also showed better performance compared to features based on statistical distribution of instantaneous frequency, calculated using Hilbert transform of intrinsic mode function after applying standard empirical mode decomposition and bivariate empirical mode decomposition to ECG. We conclude that the proposed features offer a promising approach to emotion recognition based on short ECG signals. The proposed features could be potentially used also in applications in which it is important to detect quickly any changes in emotional state

Enhancing emotion recognition from ECG signals using supervised dimensionality reduction

Abstract Dimensionality reduction (DR) is an important issue in classification and pattern recognition process. Using features with lower dimensionality helps the machine learning algorithms work more efficient. Besides, it also can improve the performance of the system. This paper explores supervised dimensionality reduction, LDA (Linear Discriminant Analysis), NCA (Neighbourhood Components Analysis), and MCML (Maximally Collapsing Metric Learning), in emotion recognition based on ECG signals from the Mahnob-HCI database. It is a 3-class problem of valence and arousal. Features for kNN (k-nearest neighbour) are based on statistical distribution of dominant frequencies after applying a bivariate empirical mode decomposition. The results were validated using 10-fold cross and LOSO (leave-one-subject-out) validations. Among LDA, NCA, and MCML, the NCA outperformed the other methods. The experiments showed that the accuracy for valence was improved from 55.8% to 64.1%, and for arousal from 59.7% to 66.1% using 10-fold cross validation after transforming the features with projection matrices from NCA. For LOSO validation, there is no significant improvement for valence while the improvement for arousal is significant, i.e. from 58.7% to 69.6%

A preliminary study in neonatal cardiorespiratory monitoring through diaphragmatic electromyography

Abstract Cardiorespiratory monitoring continues to be a challenge in the Neonatal Intensive Care Unit due to the sensitivity of current techniques to false alarms and artifacts. Surface diaphragmatic electromyography (EMGdi) can be used to measure directly the respiratory muscles activity and to reduce motion artifacts. We propose to acquire ECG and EMGdi with the electrodes placed on the diaphragm to measure heart and respiratory rate in neonates. Data from fourteen neonates was analyzed to compare the measurements of the signal acquired in the diaphragm with the ECG bipolar leads and a reference respiration signal from piezoelectric respiratory effort belt. Bland-Altman plots showed agreement between heart rate monitoring in the diaphragm with no significant differences. Detection of breaths showed similar results in the EMGdi derived wave compared with the reference signal. Thus, heart and respiration rate monitoring in neonates can be accomplished with ECG and EMG signals acquired from the diaphragm

Attention-based CNN-GRU model for automatic medical images captioning:ImageCLEF 2021

Abstract The action of understanding and interpretation of medical images is a very important task in the medical diagnosis generation. However, manual description of medical content is a major bottleneck in clinical diagnosis. Many research studies were devoted to develop automated alternatives to this process, which would have enormous impact in terms of efficiency, cost and accuracy in the clinical workflows. Different approaches and techniques have been presented in the literature ranging from traditional machine learning methods to deep learning based models. Inspired by the outperforming results of the later techniques, we present in the current paper, our team participation (RomiBed) to the ImageCLEF medical caption prediction task. We addressed the challenge of medical image captioning by combining a CNN encoder model with an attention-based GRU language generator model whereas a multi-label CNN classifier is used for the concept detection task. Using the provided data in the training, validation and test subsets, we obtain an average F_measure of 14.3% and a BLEU score of 0.243 on the ImageCLEF concept detection and the caption prediction challenges, respectively