Cox模型影响点识别诊断统计量的模拟研究

目的 探讨Cox比例风险模型影响点的有效识别方法 .方法 通过Monte-Carlo模拟研究,比较了六种诊断统计量及相应诊断图对影响点的诊断效能.结果 模拟研究表明,加权score残差、似然距离和最大影响曲率及其诊断图可从模型拟合不同角度有效识别影响点.结论 影响分析应是Cox模型分析的一个重要组成部分,加权score残差、似然距离和最大影响曲率是有效识别影响点的诊断统计量.     

西昌市静脉吸毒人群HIV发病率分析

目的在四川省西昌市静脉吸毒人群中，利用数学模型研究人类免疫缺陷病毒（HIV）发病率。方法利用对西昌市静脉吸毒人群HIV感染横断面调查获得有关数据，进行HIV数学模型分析。结果建立静脉吸毒人群中的HIV数学模型，利用横断面调查资料计算HIV发病率。结论由模型及其分析得出HIV发病率为λ=3．5％。与由队列研究所获得的发病率比较接近。     

CT模拟过程在三维适形放疗中的临床应用价值

目的:探讨CT模拟过程在三维适形放疗中的临床应用价值。方法:将三维激光定位系统、双螺旋CT机、放疗治疗计划系统及三维挡块切割机通过网络连成一体分别对492例恶性肿瘤患者进行体模制作、CT定位、制定治疗计划和切割、制作铅挡块并进行验证。结果:492例恶性肿瘤患者均顺利通过CT模拟过程.成功率达100%。其误差均在允许范围:头颈部肿瘤误差1mm±0.3;胸部肿瘤误差3mm+0.3;腹部肿瘤误差2.5mm±0.2;盆腔肿瘤误差2mm±0.4。结论:CT模拟过程是三维适形放疗的重要环节,误差小,利于保护周围正常组织和重要器官。为保证CT模拟过程准确,放疗的质量保证和质量控制是关键。     

气升式环流反应器内气液两相流动计算流体力学的模拟

采用欧拉-欧拉两流体模型模拟了气升式环流反应器内部气液两相流动过程,考察了液相速度和气含率随表观气速的变化,液相速度和气含率模拟值的关系与两种经验关系式的计算值进行了比较,两者取得了很好的一致,证明了模型的正确性。在此基础上,使用计算流体力学模拟的方法考查了反应器内的导流筒直径和导流筒高度对反应器内两相流动的影响,导流筒直径增大,液相循环量增大,上升段气含率增大;导流筒位置升高,液相循环速度和循环量均增大,上升段气含率减小。所获得的结果对气升式反应器的设计优化具有指导意义。     

一维质量矩控制系统建模与试验

为了大惯性质量控制系统硬件在环仿真的需要,研制了一种新型的控制系统试验装置。采用实测试验数据与M atlab仿真协同分析方法,完成了系统关键模块的试验建模。目前该试验系统在3°角度范围内,在受扰状态下能够自动平衡空间姿态。试验结果表明:该系统具有适于大惯性质量对象的硬件在环仿真的特点。     

电阻抗断层成像脑出血模型的仿真研究

目的：建立脑出血有限元模型,对其进行电阻抗断层成像仿真研究.方法：基于4层同心圆头模型,利用有限元方法和动态NOSER算法重构成像.结果：单病灶脑出血模型的病灶能够被准确重构呈现,而多病灶模型中邻近病灶间的边界重构较为模糊.结论：动态NOSER算法是一种有效检测脑出血的电阻抗断层成像方法.     

Application of a statistical dynamic model investigating the short-term cellular kinetics induced by riddelliine, a hepatic endothelial carcinogen.

In recent studies, riddelliine, a pyrrolizidine alkaloid, was found to increase rates of replication and apoptosis and induce hemangiosarcoma in the liver of rats and mice. To analyze DNA replication and apoptosis data taken from the same animals, we have developed a predictive mathematical model for describing BrdU labeling and apoptotic processes. The model allows the incorporation of simple diurnal patterns in cellular kinetics and is applied to data on hepatocytes and endothelial cells taken from riddelliine exposed rats. Predictions from the model were used with multivariable nonlinear regression techniques to estimate replication and apoptotic rate constants for both cell types and all treatment groups. Hypothesis tests were used with the predicted rates to separate the competing effects of riddelliine on replication and apoptosis of hepatocytes and endothelial cells as well as compare replication rates between cell types. That estimated replication rates were found to be significantly higher for endothelial cells supports the supposition of induction of hemangiosarcoma by riddelliine in the liver.     

利用SPSS软件实现药学实验中正交设计的方差分析

目的:利用SPSS软件实现药学实验中正交设计的方差分析,为药学实验提供更好的数理统计分析。方法:药学实验中经常利用正交设计来完成,再结合数理统计分析选择最佳实验条件。L8(23)、L8(24)、L9(33)、L9(34)四种正交设计是药学实验里边最常用的四种,文章利用现有文献的正交实验实例,用SPSS软件实现药学实验研究中正交设计的方差分析。结果:SPSS可以快速高效的计算出正交设计方差分析结果,灵活地选出最满意的结果。结论:SPSS软件实现正交设计的方差分析,能节省大量的时间,极大地提高工作效率,且结果更为精确。     

The Role Of Electro-Physiological Tests in the Diagnosis of Non-Organic Hearing Loss

Today it is possible, by the use of newly developed tests, to diagnose cases of non-organic hearing loss with reasonable certainty. Having once decided that there may be non-organic elements, it is useful to supplement routine pure-tone and speech audiometry with a neurophysiological test like an ERA by means of which the auditory threshold can be established without the patients subjective judgement. A hearing loss which is apparent by routine pure-tone audiometry, but which is not evident after ERA is almost certainly non-organic, although confirmation of this state of affairs by other reliable tests is advisable. Measurement of the acoustic reflex thresholds and delayed speech feedback tests are both useful in this respect and rarely cause any confusion, except in some cases of true hearing loss in strongly recruiting ears.