Simulation model of renal replacement therapy: predicting future demand in England.

BACKGROUND: The demand for renal replacement therapy (RRT) in England has risen steadily, although from a lower base than many other developed countries. Predicting the future demand for RRT and the impact of factors such as the acceptance rate, transplant supply and patient survival, is required in order to inform the planning of such services. METHODS: A discrete event simulation model estimates the future demand for RRT in England in 2010 for a range of scenarios. The model uses current prevalence and current and projected future acceptance rates, survival rates and the transitions between modalities to predict future patient numbers. National population and mortality data, published literature and data from the UK Renal Registry and UK Transplant, are used to estimate unmet need for RRT, the impact of changing demography and incidence of Type 2 diabetes, patient haemodialysis (HD) survival and transplant supply. RESULTS: By 2010 the predicted prevalence will have increased from about 30,000 in 2000 to between 42 and 51,000 (900-1000 p.m.p.), an average annual growth of 4.5-6%. Changing transplant supply has a small effect on overall numbers but changes the proportion of patients with functioning graft by up to 8%. Even with an optimistic increase in transplant supply (11% p.a. for 5 years), numbers on HD will continue to rise substantially, especially in the elderly. The factors most influencing future patient numbers are the acceptance rate and dialysis survival. CONCLUSION: This model predicts a substantial growth in the RRT population to 2010 to a rate approaching 1000 p.m.p., particularly in the elderly and those on HD, with a steady state not being reached for at least 25 years.     

WKZX微机自控系统及其应用

本文在介绍我院研制成的WKZX型微机自控系统的组成及性能基础上,提出了以微处理机为基础的数字自控系统设计及其规律。介绍了应用本装置所研究的几个实例——PWM微机伺服系统和发酵过程参数预值仿真及其控制等。     

金属换热器传热过程的数学模型及应用

应用蒙特卡洛法仿真辐射式金属换热器内的辐射传热过程，建立了换热器综合传热的数学模型，利用概率论原理，把辐射能迁移过程仿真为一定累积概率分面下的随机过程，该模型能较好地反映换热器内传热过程的真实情况，可以计算出换热器内烟气、筒壁、空气的温度和壁面热流分布，以及研究烟气进口温度、换热器筒径和狭逢宽度对换热效果的影响。     

尾部悬吊与30月龄大鼠比目鱼肌的形态学特征比较

目的 观察尾部悬吊和30月龄大鼠比目鱼肌发生萎缩过程的异同点.方法 SD雄性大鼠42只,随机分为7组,即尾部悬吊5 d、7 d、14 d组,相应的同步对照和30月鼠龄组,在各时间点制备比目鱼肌横截面冰冻切片标本,用抗MHC Ⅱ单克隆抗体进行免疫组织化学染色,计算比目鱼肌Ⅰ、Ⅱ型肌纤维横截面积并计数各型肌纤维数目.结果 与同步对照组相比,悬吊组大鼠比目鱼肌的湿重,相对湿重,Ⅰ、Ⅱ型肌纤维横截面积,经体重归一化的肌纤维横截面积均显著降低,Ⅱ型肌纤维比例显著增加,而Ⅰ型肌纤维比例减少.与14 d对照组相比,30月龄组大鼠比目鱼肌湿重和Ⅰ、Ⅱ型肌纤维横截面积均明显增大,但其相对湿重和经体重归一化的肌纤维横截面积却显著降低,与悬吊14 d组无显著差异.30月龄组大鼠比目鱼肌中Ⅰ、Ⅱ型肌纤维比例与各对照组相比亦无显著差异.结论 30月龄大鼠比目鱼肌萎缩以首先出现相对湿重与归一化肌纤维横截面积降低为特征,且发生较慢,而尾部悬吊大鼠比目鱼肌则在较短时间内发生全面萎缩.     

Using Computer Simulated Results of a Bulk Drug Substance Assay to Determine Acceptance Criteria for Method Validation

Purpose. To determine the statistical variability expected for a well designed HPLC assay of a bulk drug substance (BDS). The results are used to develop appropriate acceptance criteria for a method validation protocol as well as to evaluate the level of uncertainty expected for assay results using a variety of sampling/injection schemes. Methods. Computer simulation was used to generate a large quantity of data and the variability of the mock results was evaluated. Error propagation was also calculated, whenever possible, to confirm results obtained from the simulations. Results. Protocol acceptance criteria were developed that were consistent with the expected variability for data resulting from the execution of the validation protocol. In certain cases simulations provided the only avenue of obtaining results that could not otherwise be readily determined. Conclusions. Computer modeling can be used to obtain suitable acceptance criteria for validation results which are consistent with method variability. This is particularly significant in the case of linearity where it has been difficult to develop acceptance criteria based on anything other than analyst intuition and experience. Assay simulations clearly demonstrated that the variability expected for a typical BDS assay is large relative to the average specification range and therefore little insight about relative purity can be gained comparing individual passing assay results.     

Introducing expert systems to medical students using esta, Expert System Teaching Aid

Medical students are allocated little curriculum time for exposure to expert systems. ESTA, a computer model of an expert system, was developed to make best use of this time. The nature of the students' interaction with ESTA is described, and their reactions to the expert system concepts and the place of expert systems in medicine are presented. A discussion of these reactions draws some conclusions about teaching expert systems in particular, and computers in general, in the basic medical course.     

Prototype system for an MR simulation of intracavitary brachytherapy for cervical cancer: Preliminary results in six cases

We report a newly developed MR simulation system for intracavitary brachytherapy for cervical cancer and subsequent treatment results. MR simulation was performed on six patients. The spatial relationship of the tumor to the bladder, rectum, bowel, applicators, etc. was depicted well. Doses to the tumor and surrounding normal tissues were read from isodose curves superimposed on the T2-weighted sagittal image. This system promises to be useful in customizing the dose distribution.     

头低位限制活动对家兔主要脏器微血管壁通透性的影响

本文报导了用40只白色短毛家兔所做的动物模拟失重实验,得出各脏器微血管通透性的动态反应曲线。并用微循环研究方法,分析了模拟失重时各脏器微血管功能状态与微血管通透性之间的关系;阐述了各脏器微循环功能变化特点;并对变化机理作了初步探讨。