登革热数学模型及其应用研究（Ⅱ）——利用数学模型评价不同措施对登革热的防治效应

利用我们建立的登革热数学模型,通过计算机对5种不同的防治措施和不同时间采取措施控制登革热流行的效应进行了模拟评价。结果显示,室内滞留喷洒对控制登革热的流行最为有效;清除孳生场所有一定效果,但视清除孳生场所的程度而定;而同时采用清除孳生场所和使用蚊帐防护的措施可收到较好的防治效果,而且费用可能较低;超低容量喷洒效果较差。模拟结果表明,同一种措施,即使只提前10天实施,效果也好得多。模拟还表明,在人群中,如果70％以上的人具有特异性免疫力,即可有效地阻止同型登革病毒的输入和流行。上述模拟结果将为现场流行病学工作提供有价值的参考,同时也显示了疾病数学模型的实际应用价值。     

化工过程在线模拟和优化的软件框架

首先讨论了在线优化和企业自动化水平的关系,接着描述了过程模型的开发和实现范例,并归纳了一个在线优化软件系统的功能需求,进而描述了一个面向程的模拟优化系统的主要组成部分,最后讨论了在线优化应用的结构以及和控制策略的关系。     

Effects of Posterior Tibial Slope on a Posterior Cruciate Retaining Total Knee Arthroplasty Kinematics and Kinetics

BackgroundIt has been hypothesized that increasing posterior tibial slope can influence condylar rollback and play a role in increasing knee flexion. However, the effects of tibial slope on knee kinematics are not well studied. The objective of this study is to assess the effects of tibial slope on femorotibial kinematics and kinetics for a posterior cruciate retaining total knee arthroplasty design.MethodsA validated forward solution model of the knee was implemented to predict the femorotibial biomechanics of a posterior cruciate retaining total knee arthroplasty with varied posterior slopes of 0°-8° at 2° intervals. All analyses were conducted on a weight-bearing deep knee bend activity.ResultsIncreasing the tibial slope shifted the femoral component posteriorly at full extension but decreased the overall femoral rollback throughout flexion. With no tibial slope, the lateral condyle contacted the polyethylene 6 mm posterior of the midline, but as the slope increased to 8°, the femur shifted an extra 5 mm, to 11 mm posterior of the tibial midline. Similar shifts were observed for the medial condyle, ranging from 7 mm posterior to 13 mm posterior, respectively. Increasing posterior slope decreased the posterior cruciate ligament tension and femorotibial contact force.ConclusionThe results of this study revealed that, although increasing the tibial slope shifted the femur posteriorly at full extension and maximum flexion, it reduced the amount of femoral rollback. Despite the lack of rollback, a more posterior location of condyles suggests lower chances of bearing impingement of the posterior femur and may explain why increasing slope may lead to higher knee flexion.     

居家模拟培训对老年髋关节置换患者康复效果的影响

目的探讨开展居家模拟培训提高老年髋关节置换患者康复的效果。方法按住院时间将老年髋关节置换患者162例分为对照组80例和观察组82例,对照组采取骨科常规护理方式进行康复指导,观察组在常规护理基础上由高级责任护士实施全程居家生活与出行路径的模拟培训。于入院时、术后1个月、3个月、6个月评价两组Harris髋关节功能评分与Barthel指数。结果观察组Harris髋关节功能评分及Barthel指数评分显著高于对照组(均P<0.01)。结论开展居家模拟培训有利于促进老年髋关节置换术后患者康复,提高日常生活能力。     

金银花颗粒在旋风分离器中的流场数值模拟分析

目的 针对金银花颗粒在旋风分离器中的运动行为过程进行研究,考察不同设计参数和操作工艺条件下,颗粒在设备内部的运动过程变化规律。方法 基于仿真模拟技术,考察受不同设备长径比、入口进气雷诺数、颗粒质量流量3个因素影响的金银花颗粒在分离器内的运动规律,并以金银花颗粒得粉率为验证指标参数,对模型可靠性进行了分析。结果 通过仿真模拟得到了各个不同工艺条件下的金银花颗粒运动轨迹分布,计算出了对应设备的颗粒得粉率。提出金银花颗粒分离的最佳工艺建议为设备长径比5∶1,入口进气雷诺数3.23×10⁴,颗粒质量流量80.1 mg/s,得到的金银花颗粒得粉率为96.30%。结论 为旋风分离器内金银花颗粒的有关研究提供指导,同时改善旋风分离器在控制和设计上的不足。     

新型枢椎椎板钉导向器的应用研究

目的:通过体外试验探讨新型枢椎椎板钉导向器的安全性及准确性。方法:选取2018年1月至2018年6月行颈椎三维CT的患者40例,男21例,女19例;身高165～180(172.9±9.5) cm,年龄38～55(51.1±12.8)岁,排除枢椎椎板缺损及发育不全患者。每例患者的颈椎三维CT数据制作两套3D打印标本,共80个颈椎标本,均用于体外置钉试验。根据置钉方式的不同,体外试验部分分为导向器置钉组40个和徒手置钉组40个。同时,在计算机上重建出该40例患者的颈椎三维模型,通过计算机模拟置钉,得到理想出针点数据与理想内倾角度,此为3D模拟置钉组(理想钉道),40例。在体外试验中,分别测量导向器置钉组、徒手置钉组置入螺钉的位置危险等级、出针点位置及内倾角度。并以出针点精确性及钉道内倾角度为基准,将导向器置钉组、徒手置钉组与3D模拟置钉组数据对比,并将各组数据行统计学分析以确定准确性。结果:导向组螺钉位置可接受的为75例,位置危险的为5例,可接受率为94%,双皮质率为93%。徒手组螺钉位置可接受为62例,位置危险为18例,可接受率为78%,双皮质率33%,两组比较差异有统计学意义(P0.05)。导向器置钉组与3D模拟置钉组的出针点精确性及钉道内倾角度比较,差异无统计学意义(P0.05),徒手置钉组与3D模拟置钉组出针点精确性及钉道内倾角度比较,差异有统计学意义(P0.05)。结论:本导向器为通用型,结构稳定,导向精确,操作简便,可同时置入双侧椎板钉,缩短置钉时间,同时可有效避免双向交叉螺钉的碰撞,增加双皮质率,有效提高枢椎椎板钉置钉的效率和安全性。     

Cost-effectiveness of using hepatitis C viremic hearts for transplantation into HCV-negative recipients

Outcomes following hepatitis C virus (HCV)-viremic heart transplantation into HCV-negative recipients with HCV treatment are good. We assessed cost-effectiveness between cohorts of transplant recipients willing and unwilling to receive HCV-viremic hearts. Markov model simulated long-term outcomes among HCV-negative patients on the transplant waitlist. We compared costs (2018 USD) and health outcomes (quality-adjusted life-years, QALYs) between cohorts willing to accept any heart and those willing to accept only HCV-negative hearts. We assumed 4.9% HCV-viremic donor prevalence. Patients receiving HCV-viremic hearts were treated, assuming $39 600/treatment with 95% cure. Incremental cost-effectiveness ratios (ICERs) were compared to a $100 000/QALY gained willingness-to-pay threshold. Sensitivity analyses included stratification by blood type or region and potential negative consequences of receipt of HCV-viremic hearts. Compared to accepting only HCV-negative hearts, accepting any heart gained 0.14 life-years and 0.11 QALYs, while increasing costs by $9418/patient. Accepting any heart was cost effective (ICER $85 602/QALY gained). Results were robust to all transplant regions and blood types, except type AB. Accepting any heart remained cost effective provided posttransplant mortality and costs among those receiving HCV-viremic hearts were not >7% higher compared to HCV-negative hearts. Willingness to accept HCV-viremic hearts for transplantation into HCV-negative recipients is cost effective and improves clinical outcomes.     

Projecting the impact of a two-dose COVID-19 vaccination campaign in Ontario,Canada

BackgroundA number of highly effective COVID-19 vaccines have been developed and approved for mass vaccination. We evaluated the impact of vaccination on COVID-19 outbreak and disease outcomes in Ontario, Canada.MethodsWe used an agent-based transmission model and parameterized it with COVID-19 characteristics, demographics of Ontario, and age-specific clinical outcomes. We implemented a two-dose vaccination program according to tested schedules in clinical trials for Pfizer-BioNTech and Moderna vaccines, prioritizing healthcare workers, individuals with comorbidities, and those aged 65 and older. Daily vaccination rate was parameterized based on vaccine administration data. Using estimates of vaccine efficacy, we projected the impact of vaccination on the overall attack rate, hospitalizations, and deaths. We further investigated the effect of increased daily contacts at different stages during vaccination campaigns on outbreak control.ResultsMaintaining non-pharmaceutical interventions (NPIs) with an average of 74% reduction in daily contacts, vaccination with Pfizer-BioNTech and Moderna vaccines was projected to reduce hospitalizations by 27.3% (95% CrI: 22.3% − 32.4%) and 27.0% (95% CrI: 21.9% − 32.6%), respectively, over a one-year time horizon. The largest benefits of vaccination were observed in preventing deaths with reductions of 31.5% (95% CrI: 22.5% − 39.7%) and 31.9% (95% CrI: 22.0% − 41.4%) for Pfizer-BioNTech and Moderna vaccines, respectively, compared to no vaccination. We found that an increase of only 10% in daily contacts at the end of lockdown, when vaccination coverage with only one dose was 6%, would trigger a surge in the outbreak. Early relaxation of population-wide measures could lead to a substantial increase in the number of infections, potentially reaching levels observed during the peak of the second wave in Ontario.ConclusionsVaccination can substantially mitigate ongoing COVID-19 outbreaks. Sustaining population-wide NPIs, to allow for a sufficient increase in population-level immunity through vaccination, is essential to prevent future outbreaks.     

神经系统轴突三维定向生长的数值模拟

目的研究轴突在三维组织中的定向生长问题,探讨轴突沿非平坦基底定向生长时基底的低起伏程度对轴突的生长速率、成束和解束速率的影响。方法根据实验观察,设轴突生长的牵引力与靶细胞分泌的可扩散吸引分子的浓度梯度成正比,轴突成束和解束的侧向力与生长锥分泌的可扩散吸引分子和排斥分子的浓度梯度成正比,并且,吸引力指向浓度高的方向,排斥力指向浓度低的方向,浓度满足扩散方程。对于非平坦基底,有效力为沿基底轮廓线的切向分量。数值计算采用三维有限差分法和改进的Euler法。结果(1)轴突在三维组织中定向生长的基本特征与在二维培养基实验中的观察是一致的,只是在形态上有三维与二维之分;(2)非平坦基底的低起伏程度影响轴突的生长,随着起伏加剧,生长锥的前进速率减小、侧向速率增加。结论(1)许多基于二维培养实验所揭示的轴突生长的基本规律在三维情况下仍然是成立的;(2)基底的几何性质是影响轴突生长速率的重要因素之一。