A mathematical model of the bellows dispersion system is developed by combining the interior ballistic theory with structural dynamics theory to describe the deformation course of bellows. By analyzing the physical mo...A mathematical model of the bellows dispersion system is developed by combining the interior ballistic theory with structural dynamics theory to describe the deformation course of bellows. By analyzing the physical model of the bellows dispersion system, the dispersion course is divided into three stages. For each stage, mathematical model is built and its terminal conditions are given. The numerical simulation is based on the Runge-Kutta method and differential quadrature method. Simulation results of the model agree with those of the model built by only interior ballistics theory. However, this model is congruous with the actual dispersion course and can more easily determine the dispersion time and submunition displacement.展开更多
Colon cancer remains a significant clinical problem worldwide and in the United States it is the third most common cancer diagnosed in men and women.It is generally accepted that most malignant neoplasms of the colon ...Colon cancer remains a significant clinical problem worldwide and in the United States it is the third most common cancer diagnosed in men and women.It is generally accepted that most malignant neoplasms of the colon arise from precursor adenomatous polyps.This stepwise progression of normal epithelium to carcinoma,often with intervening dysplasia,occurs as a result of multiple sequential,genetic mutations-some are inherited while others are acquired.Malignant polyps are defined by the presence of cancer cells invading through the muscularis mucosa into the underlying submucosa(T1).They can appear benign endoscopically but the presence of malignant invasion histologically poses a difficult and often controversial clinical scenario.Emphasis should be initially focused on the endoscopic assessment of these lesions.Suitable polyps should be resected en-bloc,if possible,to facilitate thorough evaluation by pathology.In these cases,proper attention must be given to the risks of residual cancer in the bowel wall or in the surrounding lymph nodes.If resection is not feasible endoscopically,thenthese patients should be referred for surgical resection.This review will discuss the important prognostic features of malignant polyps that will most profoundly affect this risk profile.Additionally,we will discuss effective strategies for their overall management.展开更多
文摘A mathematical model of the bellows dispersion system is developed by combining the interior ballistic theory with structural dynamics theory to describe the deformation course of bellows. By analyzing the physical model of the bellows dispersion system, the dispersion course is divided into three stages. For each stage, mathematical model is built and its terminal conditions are given. The numerical simulation is based on the Runge-Kutta method and differential quadrature method. Simulation results of the model agree with those of the model built by only interior ballistics theory. However, this model is congruous with the actual dispersion course and can more easily determine the dispersion time and submunition displacement.
文摘Colon cancer remains a significant clinical problem worldwide and in the United States it is the third most common cancer diagnosed in men and women.It is generally accepted that most malignant neoplasms of the colon arise from precursor adenomatous polyps.This stepwise progression of normal epithelium to carcinoma,often with intervening dysplasia,occurs as a result of multiple sequential,genetic mutations-some are inherited while others are acquired.Malignant polyps are defined by the presence of cancer cells invading through the muscularis mucosa into the underlying submucosa(T1).They can appear benign endoscopically but the presence of malignant invasion histologically poses a difficult and often controversial clinical scenario.Emphasis should be initially focused on the endoscopic assessment of these lesions.Suitable polyps should be resected en-bloc,if possible,to facilitate thorough evaluation by pathology.In these cases,proper attention must be given to the risks of residual cancer in the bowel wall or in the surrounding lymph nodes.If resection is not feasible endoscopically,thenthese patients should be referred for surgical resection.This review will discuss the important prognostic features of malignant polyps that will most profoundly affect this risk profile.Additionally,we will discuss effective strategies for their overall management.
