Despite of the limitation in modeling infinite space, the finite element method(FEM) is one of the most used tools to numerically study the geotechnical problems regarding the capacity of simulating different geometri...Despite of the limitation in modeling infinite space, the finite element method(FEM) is one of the most used tools to numerically study the geotechnical problems regarding the capacity of simulating different geometries, conditions and material behaviors. A kind of absorbing layer named perfectly matched layer(PML) has been applied to modeling the radiation damping using FEM, which makes the dynamic analysis of soil-structure interaction more accurate. The PML is capable of absorbing incident waves under any angle and frequency, ensuring them to pass through the model boundaries without reflection.In this context, a new FEM program has been written and the PML formula has been implemented by rewriting the dynamic equation of motion and deriving new properties for the quadrilateral elements.The analysis of soil-foundation interaction by applying the PML is validated by the evaluation of impedance/compliance functions for different ground conditions. The results obtained from the PML model match the extended mesh results, even though the domain is small enough that other types of absorbing boundaries can reflect waves back to the foundation. The mechanism of the wave propagation in the region shows that the forced vibrations can be fully absorbed and damped by the boundaries surrounded by PMLs which is the role of radiation damping in FEM modeling.展开更多
Objective: Coronary Artery Disease (CAD) would continue to concern medical society in the foreseeable future. Determining the extent of coronary luminal stenosis is a key factor in management of CAD. Methods presently...Objective: Coronary Artery Disease (CAD) would continue to concern medical society in the foreseeable future. Determining the extent of coronary luminal stenosis is a key factor in management of CAD. Methods presently used are costly and pose certain dangers, ranging from nephrotoxicity to death. Long Pentraxin or Pentraxin-3 (PTX3) has been used to predict survival or atherosclerotic process, but not to identify coronary stenosis. Calcium Score has been used to this end with some success. Methods: Individuals with chronic stable angina, without evidence of Myocardial Infarction (MI), who were categorized as intermediate-risk after completing a treadmill exercise test, according to Duke Protocol, underwent cardiac catheterization. In addition, blood samples were drawn for coronary sinus PTX3, and also PTX3, uric acid, high-sensitivity C-reactive protein (hs-CRP), cholesterol, glucose and High-Density Lipo-protein (HDL) in peripheral circulation. Calcium Scores were calculated using Agatston Score and non-contrast multi-slice CT scan. Participants were divided according to the number of stenotic coronary arteries (patent, one-, two-and three-vessel disease). Results: We found that PTX3 levels in coronary sinus and femoral vein correlated with each other, after log-transforming the values. Also we found that PTX3 levels and Calcium Scores differed among individuals with triple-vessel involvement and individuals without significant stenosis in any of coronary arteries. No significant differences were observed, regarding hs-CRP levels. Conclusion: PTX3 levels in periphery correlate with those in coronary arteries, and this variable can be measured with a less invasive procedure. In addition to Calcium Score, PTX3 levels are different in our four groups. The combined contribution of PTX3 and calcium score may help us identify individuals with significant coronary artery stenosis without needing to perform cardiac catheterization in a select group of patients.展开更多
文摘Despite of the limitation in modeling infinite space, the finite element method(FEM) is one of the most used tools to numerically study the geotechnical problems regarding the capacity of simulating different geometries, conditions and material behaviors. A kind of absorbing layer named perfectly matched layer(PML) has been applied to modeling the radiation damping using FEM, which makes the dynamic analysis of soil-structure interaction more accurate. The PML is capable of absorbing incident waves under any angle and frequency, ensuring them to pass through the model boundaries without reflection.In this context, a new FEM program has been written and the PML formula has been implemented by rewriting the dynamic equation of motion and deriving new properties for the quadrilateral elements.The analysis of soil-foundation interaction by applying the PML is validated by the evaluation of impedance/compliance functions for different ground conditions. The results obtained from the PML model match the extended mesh results, even though the domain is small enough that other types of absorbing boundaries can reflect waves back to the foundation. The mechanism of the wave propagation in the region shows that the forced vibrations can be fully absorbed and damped by the boundaries surrounded by PMLs which is the role of radiation damping in FEM modeling.
文摘Objective: Coronary Artery Disease (CAD) would continue to concern medical society in the foreseeable future. Determining the extent of coronary luminal stenosis is a key factor in management of CAD. Methods presently used are costly and pose certain dangers, ranging from nephrotoxicity to death. Long Pentraxin or Pentraxin-3 (PTX3) has been used to predict survival or atherosclerotic process, but not to identify coronary stenosis. Calcium Score has been used to this end with some success. Methods: Individuals with chronic stable angina, without evidence of Myocardial Infarction (MI), who were categorized as intermediate-risk after completing a treadmill exercise test, according to Duke Protocol, underwent cardiac catheterization. In addition, blood samples were drawn for coronary sinus PTX3, and also PTX3, uric acid, high-sensitivity C-reactive protein (hs-CRP), cholesterol, glucose and High-Density Lipo-protein (HDL) in peripheral circulation. Calcium Scores were calculated using Agatston Score and non-contrast multi-slice CT scan. Participants were divided according to the number of stenotic coronary arteries (patent, one-, two-and three-vessel disease). Results: We found that PTX3 levels in coronary sinus and femoral vein correlated with each other, after log-transforming the values. Also we found that PTX3 levels and Calcium Scores differed among individuals with triple-vessel involvement and individuals without significant stenosis in any of coronary arteries. No significant differences were observed, regarding hs-CRP levels. Conclusion: PTX3 levels in periphery correlate with those in coronary arteries, and this variable can be measured with a less invasive procedure. In addition to Calcium Score, PTX3 levels are different in our four groups. The combined contribution of PTX3 and calcium score may help us identify individuals with significant coronary artery stenosis without needing to perform cardiac catheterization in a select group of patients.
