32 research outputs found

    Wireless capacitive-based ECG sensing for feature extraction and mobile health monitoring

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    In this paper, the concept of a wireless wearable device capable of measuring electrocardiogram (ECG) and respiration rate (RR) through the use of non-contact capacitive-based electrodes was designed and implemented. Both ECG and RR were measured using only the active electrodes and an analog conditioning circuit. The device utilizes Bluetooth low energy for low-power wireless communication to the remote server. The measured data is used to calculate heart rate variability, RR, and extract ECG related features. It was found that the use of non-contact active chest electrodes is a viable approach for measurement. The system focuses on user comfort and the minimization of the ratio of the number of wearable sensors to sensed physiological parameters.The National Research Foundation of South Africa under Grant IFR160118156967 and Grant RDYR160404161474.http://ieee-sensors.org/sensors-journalhj2018Electrical, Electronic and Computer Engineerin

    Effect of Muscle Length on Cross-Bridge Kinetics in Intact Cardiac Trabeculae at Body Temperature

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    Dynamic force generation in cardiac muscle, which determines cardiac pumping activity, depends on both the number of sarcomeric cross-bridges and on their cycling kinetics. The Frank–Starling mechanism dictates that cardiac force development increases with increasing cardiac muscle length (corresponding to increased ventricular volume). It is, however, unclear to what extent this increase in cardiac muscle length affects the rate of cross-bridge cycling. Previous studies using permeabilized cardiac preparations, sub-physiological temperatures, or both have obtained conflicting results. Here, we developed a protocol that allowed us to reliably and reproducibly measure the rate of tension redevelopment (ktr; which depends on the rate of cross-bridge cycling) in intact trabeculae at body temperature. Using K+ contractures to induce a tonic level of force, we showed the ktr was slower in rabbit muscle (which contains predominantly β myosin) than in rat muscle (which contains predominantly α myosin). Analyses of ktr in rat muscle at optimal length (Lopt) and 90% of optimal length (L90) revealed that ktr was significantly slower at Lopt (27.7 ± 3.3 and 27.8 ± 3.0 s−1 in duplicate analyses) than at L90 (45.1 ± 7.6 and 47.5 ± 9.2 s−1). We therefore show that ktr can be measured in intact rat and rabbit cardiac trabeculae, and that the ktr decreases when muscles are stretched to their optimal length under near-physiological conditions, indicating that the Frank–Starling mechanism not only increases force but also affects cross-bridge cycling kinetics

    An overview of numerical methodologies for durability assessment of vehicle and transport structures

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    Numerical methodologies for assessing the durability of vehicle and transport structures are reviewed. These methodologies are mapped in terms of a framework that emphasizes the relationships among them. Load inputs are obtained from either measurements or simulation. These loads are used as inputs into stress analyses, which may be either quasi-static or dynamic, and either in the time domain or in the frequency domain. The outputs of these analyses can then be used in fatigue analyses. The advantages and disadvantages of each method are analysed. A case study is described to demonstrate the insights gained from the mapping framework.https://inderscience.metapress.com/ai201
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