ABSTRACT
Objective To compare the action effect of traditional and modified lumbar massage obliquity manipulation with different degrees of lumbar degeneration. Methods The biomechanical model of quality-spring-damping system lumbar spine was established and massage forces from professional massage doctors were collected. The force was used as input of the model, and lumbar degeneration was simulated by increasing elastic coefficient of the spring and damping coefficient of the damping in the model. By using MATLAB/ Simulink simulation technology, the effects of massage obliquity manipulation ( the maximum relative displacement and maximum acceleration) with different degrees of lumbar degeneration were obtained for comparative analysis.Results When the lumbar spine was degenerative, the maximum relative displacement and maximum acceleration of each segment were obtained under two manipulations. With the increase of lumbar degenerationdegree, the maximum relative displacement and maximum acceleration of each segment under two manipulations showed a downward trend, and the attenuation rate of the maximum relative displacement and maximum acceleration of each segment under two manipulations was obtained. Conclusions When degenerative changes in the spine do not occur, the effectiveness of traditional lumbar massage obliquity manipulation is slightly better than that of modified lumbar massage obliquity manipulation, but the safety of modified lumbar massage obliquity manipulation is obviously better than that of the traditional lumbar massage obliquity manipulation, so the modified lumbar massage obliquity manipulation should be used. With the aggravation of lumbar degeneration, the action effects of two manipulations are attenuated in a power function. The attenuation rate of effectiveness of modified lumbar massage obliquity manipulation is significantly faster than that of traditional lumbar massage obliquity manipulation, indicating that the modified lumbar massage obliquity manipulation should not be used in the caseof lumbar degeneration.
ABSTRACT
Although complex fractionated electrogram (CFE) is known to be a target for catheter ablation of fibrillation, its physiological meaning in fibrillation wave-dynamics remains to be clarified. We evaluated the spatiotemporal relationships among the parameters of fibrillation wave-dynamics by simulation modeling. We generated maps of CFE-cycle length (CFE-CL), local dominant frequency (LDF), wave break (WB), and phase singularity (PS) of fibrillation in 2-dimensional homogeneous bidomain cardiac modeling (1,000 x 1,000 cells ten Tusscher model). We compared spatiotemporal correlations by dichotomizing each maps into 10 x 10 lattice zones. In spatial distribution, WB and PS showed excellent correlation (R = 0.963, P < 0.001). CFE-CL had weak correlations with WB (R = 0.288, P < 0.001), PS (R = 0.313, P < 0.001), and LDF (R = -0.411, P < 0.001). However, LDF did not show correlation with PS or WB. PSs were mostly distributed at the periphery of low CFE-CL area. Virtual ablation (5% of critical mass) of CFE-CL < 100 ms terminated fibrillation at 14.3 sec, and high LDF ablation (5% of critical mass) changed fibrillation to organized tachycardia, respectively. In homogeneous 2D fibrillation modeling, CFE-CL was weakly correlated with WB, PS, and LDF, spatiotemporally. PSs are mostly positioned at the periphery of low CFE-CL areas, and virtual ablation targeting low CFE-CL regions terminated fibrillation successfully.
Subject(s)
Humans , Algorithms , Atrial Fibrillation/physiopathology , Body Surface Potential Mapping , Catheter Ablation , Electrocardiography , Electrodes , Heart Atria/physiopathology , Models, BiologicalABSTRACT
Objective To carry out quantitative investigation on application of emulational trunk dummy (ETD) in evaluating the opening shock of life saving parachute and provide a more reliable test method for further development. Method ETD equipped with parachute was tested in the impact experiment, where a 63.4 kg impact block was dropped from the height of 0.20 m，0.40 m，0.60 m，0.80 m respectively to simulate different opening shocks. The opening shocks were deducted by measured forces on harness and acceleration loads at the center of dummy's thorax. For comparison, 5 rigid trunk dummies (RTD) were tested under the equivalent impacts. As the contrast test, 24 male healthy subjects were also exposed under such impacts with standing and sitting posture respectively. Results Under the same impact, the peak impact value on harness exhibited maximum on RTD, minimum on subjects with sitting posture, and medium on ETD. There were significant differences between each experimental group (P<0.01). With different impact loads, the peak impact value on ETD was 2 795，3 873，4 816 and 5 736 N respectively, which was correspondingly close to that of subjects with standing posture(2 541，3 042，3 720 and 4250 N). Conclusions The result of opening shock gathered from ETD is closer to that from RTD due to ETD’s viscoelasticity, which shall certainly influence the measured opening shock. Therefore, ETD is suggested to be used in the development of live saving parachute.