A new parameter transformation alpha = alpha (epsilon, n omega (0)/m, omega (l)) was defir2ed for extending the applicable range of the modified Lindstedt-Poincare method. It is suitable for determining subharmonic an...A new parameter transformation alpha = alpha (epsilon, n omega (0)/m, omega (l)) was defir2ed for extending the applicable range of the modified Lindstedt-Poincare method. It is suitable for determining subharmonic and ultraharmonic resonance solutions of strongly nonlinear systems. The 1/3 subharmonic and 3 ultraharmonic resonance solutions of the Duffing equation and the 1/2 subharmonic resonance solution of the Van der Pol-Mathieu equation were studied. These examples show approximate solutions are in good agreement with numerical solutions.展开更多
Background Innovative advancements in ultrasound instrumentation present a number of imaging modalities for myocardial contrast echocardiography （MCE） in ischemic syndromes. How well they compare to each other in di...Background Innovative advancements in ultrasound instrumentation present a number of imaging modalities for myocardial contrast echocardiography （MCE） in ischemic syndromes. How well they compare to each other in diagnostic accuracy in the detection of acute myocardial infarction is unclear. The purpose of this study was to assess the relative accuracy of 3 different imaging modes of MCE, low mechanical index （MI） real-time perfusion imaging （RTPI）, triggered harmonic angio mode （HA）, and ultraharmonic imaging mode （UH） in the detection of acute experimental myocardial infarction within the time frame suitable for potential reperfusion. Methods MCE was performed in 10 open-chest dogs using RTPI, triggered HA and triggered UH modes at baseline and one hour after occlusion of left anterior descending coronary artery. Presence or absence of peffusion defects, and the perfusion defect size when present, were analyzed and compared with the infarct size delineated by triphenyltetrazolium chloride （TTC） staining. Results The infarct area was （15.8-2.4）% by TTC staining; Peffusion defect area by MCE was similar to anatomic infarct area in all the three MCE approaches： （16.1-2.7）% by RTPI mode, （15.5-2.9）% by HA mode, and （15.5-3.0）% by UH mode. The sensitivity, specificity and overall diagnostic accuracy in the detection of myocardial infarction were 100%, 88%, and 94% for RTPI mode, 88%, 100%, and 94 % for HA mode, and 100%, 75%, and 88% for UH mode. Conclusion All modes of MCE, RTPI, triggered HA mode and triggered UH mode have excellent diagnostic accuracy in the immediate hour of acute coronary occlusion within the optimal time frame suitable for reperfusion therapy.展开更多
文摘A new parameter transformation alpha = alpha (epsilon, n omega (0)/m, omega (l)) was defir2ed for extending the applicable range of the modified Lindstedt-Poincare method. It is suitable for determining subharmonic and ultraharmonic resonance solutions of strongly nonlinear systems. The 1/3 subharmonic and 3 ultraharmonic resonance solutions of the Duffing equation and the 1/2 subharmonic resonance solution of the Van der Pol-Mathieu equation were studied. These examples show approximate solutions are in good agreement with numerical solutions.
文摘Background Innovative advancements in ultrasound instrumentation present a number of imaging modalities for myocardial contrast echocardiography （MCE） in ischemic syndromes. How well they compare to each other in diagnostic accuracy in the detection of acute myocardial infarction is unclear. The purpose of this study was to assess the relative accuracy of 3 different imaging modes of MCE, low mechanical index （MI） real-time perfusion imaging （RTPI）, triggered harmonic angio mode （HA）, and ultraharmonic imaging mode （UH） in the detection of acute experimental myocardial infarction within the time frame suitable for potential reperfusion. Methods MCE was performed in 10 open-chest dogs using RTPI, triggered HA and triggered UH modes at baseline and one hour after occlusion of left anterior descending coronary artery. Presence or absence of peffusion defects, and the perfusion defect size when present, were analyzed and compared with the infarct size delineated by triphenyltetrazolium chloride （TTC） staining. Results The infarct area was （15.8-2.4）% by TTC staining; Peffusion defect area by MCE was similar to anatomic infarct area in all the three MCE approaches： （16.1-2.7）% by RTPI mode, （15.5-2.9）% by HA mode, and （15.5-3.0）% by UH mode. The sensitivity, specificity and overall diagnostic accuracy in the detection of myocardial infarction were 100%, 88%, and 94% for RTPI mode, 88%, 100%, and 94 % for HA mode, and 100%, 75%, and 88% for UH mode. Conclusion All modes of MCE, RTPI, triggered HA mode and triggered UH mode have excellent diagnostic accuracy in the immediate hour of acute coronary occlusion within the optimal time frame suitable for reperfusion therapy.
