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Race 1 wave 85 font free11/8/2022 ![]() ![]() A raw PPG signal generally includes pulsatile and non-pulsatile blood volume. Thus, the PPG signal is a complex mixture of the blood flow in veins and arteries of the cardiovascular circulatory system. Indeed, the sensor coverage area includes both veins and arteries, and numerous capillaries. In other words, PPG detects the change of blood volume by the photoelectric technique, whether transmissive or reflective, to record the volume of blood in the sensor coverage area to form a PPG signal. Since the amount of optical absorption or reflection depends on the amount of blood that is present in the optical path, the PPG signal is responsive to changes in the volume of the blood, rather than the pressure of the blood vessels. Although the technology is not yet mature, it is anticipated that in the near future, accurate, continuous BP measurements may be available from mobile and wearable devices given their vast potential.įirst explored in the 1930’s, PPG is a method for measuring the amount of light that is absorbed or reflected by blood vessels in living tissue. We also review the combined use of features extracted from PPG and other physiological signals in estimating BP. Past studies on changes in PPG signals and BP are highlighted, and the correlation between PPG signals and BP are discussed. In this article, we review (i) the state-of-the-art and the literature related to PPG signals collected by pulse oximeters, (ii) various theoretical approaches that have been adopted in PPG BP measurement studies, and (iii) the potential of PPG measurement devices as a wearable application. Recent advances include the development of smartphones and wearable devices that collect pulse oximeter signals. Race 1 wave 85 font free portable#PPG technology is becoming more readily available, inexpensive, convenient, and easily integrated into portable devices. One possible solution is photoplethysmography (PPG), which is most commonly used in pulse oximetry in clinical settings for measuring oxygen saturation. For outpatient care as well as general health monitoring, there is great interest in being able to accurately and frequently measure BP outside of a clinical setting, using mobile or wearable devices. High blood pressure is associated with many chronic disease conditions, and is a major source of mortality and morbidity around the world. Religion uses nearly all forms of diffusion to reproduce itself across space.The measurement of blood pressure (BP) is critical to the treatment and management of many medical conditions. Hierarchical diffusion generally involves the conversion of a king, emperor, or other leader who then influences others to convert. Relocation diffusion, often through missionary work, brings “great leaps forward” by crossing space to secure footholds in far-away places. Contagious diffusion is most often seen in a religious context as the result of direct proselytizing. All these forms of diffusion produce patterns of diffusion that are complex. It is impossible to know why certain religions have appeal in particular times or places, but they do, and that appeal can wear off over time.Īnother important thing to remember is that the religious landscape is just a snapshot. In the same way that it has always changed, it will continue to do so. These maps can reinforce this idea in that they demonstrate the historical nature of current religious distributions. Remind yourself that these religious expansions occurred at different times. ![]() This will help explain why some places will become Buddhist or Christian at one point in history, but become Muslim at another. 6.3.1 The Diffusion of Buddhismīuddhism originated near the current Nepalese-Indian border. Like many other religions, it spread in other directions, particularly to the south and east ( Figure 6.12). This map shows the distinct waves of the diffusion of Buddhism.ĭue to its position as the oldest large, universalizing religion, Buddhism is a good example of the lifecycle of a religion. It spread in all directions but looking at a current religious map reveals that the process did not end 1500 years ago.įrom its origins, the religion spread across what is now India and Nepal. Much of its territory on the Indian subcontinent would become mostly Hindu or Muslim. ![]()
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