machine learning Article 4 human 4 mathematical model 4 Humans 3 adult 3 artificial neural network 3 electrocardiography 3 female 3 male 3 nerve cell network 3 signal noise ratio 3 Classification (of information) 2 Electrocardiography 2 Monitoring 2 Wearable Electronic Devices 2 Wearable sensors 2 Wrist 2 algorithm 2 breathing 2 breathing rate 2 electrocardiogram 2 electroencephalography 2 electronic device 2 feature extraction 2 heart failure 2 heart rate 2 heart rate variability 2 human experiment 2 learning algorithm 2