Photoplethysmogram (PPG) signals are widely used for wearable electronic devices nowadays. The PPG signal is extremely sensitive to the motion artifacts (MAs) caused by the subject's movement. The detection and removal of such MAs remains a difficult problem. Due to the complicated MA signal waveforms, none of the existing techniques can lead to satisfactory results. In this paper, a new framework to identify and tailor the abrupt MAs in PPG is proposed, which consists of feature extraction, change-point detection, and MA removal. In order to achieve the optimal performance, a data-dependent frame-size determination mechanism is employed. Experiments for the heart-beat-rate-measurement application have been conducted to demonstrate the effectiveness of our proposed method, by a correct detection rate of MAs at 98% and the average heart-beat-rate tracking accuracy above 97%. On the other hand, this new framework maintains the original signal temporal structure unlike the spectrum-based approach, and it can be further applied for the calculation of blood oxygen level (SpO₂).
Artifacts* ; Hand ; Methods ; Oxygen

In addition to its well established role as a neurotransmitter, extracellular ATP has been considered as a paracrine/autocrine factor, either released from sperm or epithelial cells, in the male reproductive tract and shown to play a versatile role in modulating various reproductive functions. This review summarizes the signal pathways through which ATP induces anion secretion by the epithelia of the epididymis, as well as its epithelium-dependent modulation of smooth muscle contraction of the vas deferens. Finally, the overall role of ATP in coordinating various reproductive events in the male genital tract is discussed.
Adenosine Triphosphate ; physiology ; Animals ; Epididymis ; physiology ; Epithelium ; physiology ; Humans ; Male ; Muscle Contraction ; Muscle, Smooth ; physiology ; Signal Transduction ; Urogenital System ; physiology ; Vas Deferens ; physiology