Tuberculosis screening among children and adolescents in China:insights from a mathematical model

Background Tuberculosis(TB)continues to be prevalent in China also among children and adolescents in China.We built a dynamic mathematical model for TB transmission in China,and applied it to compare the epidemic trends 2021–2030 under a range of screening interventions focusing on children and adolescents.Methods We developed a dynamic mathematical model with a flexible structure.The model can be applied either stochastically or deterministically,and can encompass arbitrary age structure and resistance levels.In the present version,we used the deterministic version excluding resistance but including age structure with six groups:0–5,6–11,12–14,15–17,18–64,and 65 years and above.We parameterized the model by literature data and fitting it to case and death estimates provided by the World Health Organization.We compared the new TB cases and TB-related deaths in each age group over the period 2021–2030 in 10 scenarios that involved intensified screening of particular age groups of children,adolescents,or young adults,or decreased or increased diagnostic accuracy of the screening.Results Screening the entire age class of 18-year-old persons would prevent 517,000 TB cases and 14,600 TB-related deaths between years 2021 and 2030,corresponding to 6.6%and 5.5%decrease from the standard of care projection,respectively.Annual screening of children aged 6–11 and,to a lesser extent,0–5 years,also reduced TB incidence and mortality,particularly among children of the respective ages but also in other age groups.In contrast,intensified screening of adolescents did not have a major impact.Screening with a simpler and less accurate method resulted in worsened outcomes,which could not be offset by more intensive screening.More accurate screening and better sensitivity to detect latent TB could prevent 2.3 million TB cases and 68,500 TB deaths in the coming 10 years.Conclusion Routine screening in schools can efficiently reduce the burden of TB in China.Screening should be intensified particularly among children in primary school age.

Simulation of Screening Process Based on MATLAB/Simulink

Screening is an important process in mineral industry. In this paper, a study has been made to simulate the screening process based on a high-performance MATLAB/Simulink software, with an example of simulating the sieving process of a vibrating screen. A simulation model of the sieving process with a vibrating screen （SMSPVS） was proposed, using correlative mathematical models and Simulink blocks. The results show that the simulation data was very close to the actual data, The minimum errors of size distribution of oversize and undersize are 0.65% and 0.20%, resoectivelv. The sieving orocess can be accurately simulated by the SMSPVS.

Evaluating the Effectiveness of Targeted Public Health Control Strategies for Chlamydia Transmission in Omaha, Nebraska: A Mathematical Modeling Approach

Objectives: Sexually Transmitted Infections (STIs) have a great public health impact globally. STIs are one of the most critical health problems in the United States of America (USA). Here, we present a mathematical model for testing several interventions that are designed for various communities in order to control the Chlamydia epidemic. Study Design: Based on a community sexual behavior survey, we constructed and parameterized a mathematical disease transmission model to estimate the spread dynamics of Chlamydia in young adults in the northern part of Omaha, Nebraska. Methods: A differential equations based continuous time simulation model is run for various scenarios. The model considers only one age group i.e., 19 - 25 ages, which is considered as the highest risk group for this sexually transmitted disease. Our model assumes homogeneous mixing within this age group and use published estimates to model mixing rates between individuals. Results: The presented model quantified the potential value of screening and treatment programs for Chlamydia in reducing the burden of disease in this specific community. By increasing the screening and treatment rates from 35% to 85%, great public health benefit can be achieved in two years, i.e., total cases reduction around 9% just in this considered age group. Conclusions: Computational results show that behavioral change based interventions on prevention have some effect on reducing the prevalence in the targeted age group;however, more benefit can be obtained with frequent screening and treatment programs.

Mathematical modelling of the progression of active tuberculosis:Insights from fluorography data

Little is known about the dynamics of the early stages of untreated active pulmonary tuberculosis:unknown are both the rates of progression and the model“scheme”.The“parallel”scheme assumes that infectiousness of tuberculosis cases is effectively predefined at the onset of the disease,and the“serial”scheme considers all cases to be noninfectious at the onset,with some of them later becoming infectious.Our aim was to estimate the progression of the early stages of pulmonary tuberculosis using data from a present-day population.We used the routine notification data from Moscow,Russia,2013e2018 that contained the results and time of the last fluorographic screening preceding the detection of tuberculosis cases.This provided time limits on the duration of untreated tuberculosis.Parameters of TB progression under both models were estimated.By the goodness of fit to the data,we could prefer neither the“parallel”,nor the“serial”model,although the latter had a bit worse fit.On the other hand,the observed rise in the fraction of infectious tuberculosis cases with the time since the last screening was explained by the“serial”model in a more plausible way e as gradual progression of some cases to infectiousness.The“parallel”model explained it through less realistic quick removal of non-infectious cases and accumulation of the infectious ones.The results demonstrate the potential of using such detection data enriched with reassessments of the previous screenings.

Application of defin让ive screening design to quantify the effects of process parameters on key granule characteristics and optimize operating parameters in pulsed-spray fluid-bed granulation

The pulsed-spray fluid-bed granulation (PSFBG) process was investigated and optimized using definitive scree ning design, a recently proposed new class of three-level desig n of experiment method. Such a design enabled quadratic models to be established that described the effect of six in put process parameters - inlet air temperature, inlet air humidity, binder spray rate, atomization pressure, pulse period, and pulse width - on the granule quality in a PSFBG process. Mathematical models of the mean particle size, relative size distribution width, production yield, and porosity were developed to quantify the relationships between the in flue ncing factors and critical quality attributes. On the basis of con strai nts on the desired granule properties, a design space for PSFBG was determined and ranges of the operating parameters were defined. An acceptable degree of prediction was confirmed by validation experiments, demonstrating the reliability and effectiveness of using definitive screening design to study the PSFBG process. This method can accelerate screening and optimization of this process within a large multidimensional design space.

Planning the hepatitis C virus elimination in Cyprus:A modeling study

BACKGROUND Hepatitis C virus(HCV)infection is a major global public health problem.In the Republic of Cyprus,the estimated prevalence of chronic hepatitis C(CHC)among the general population is 0.6%,while the CHC prevalence among people who inject drugs(PWID)is estimated at 46%.Direct-acting antivirals that can eliminate HCV are not yet widely available in the Republic of Cyprus.However,when direct-acting antivirals become available,a long-term strategic plan to guide elimination efforts will be needed to maximize the effect of treatment.AIM To determine the programmatic targets to eliminate HCV in the Republic of Cyprus.METHODS A dynamic,stochastic,individual-based model of HCV transmission,disease progression,and cascade of care was calibrated to data from Cyprus.The model stratifies the population into the infected general population and the PWID population.A variety of test,prevention,and treatment strategies concerning the general population,PWID,or both were examined.The time horizon of the analysis was until 2034.RESULTS Under the status quo scenario,the model predicted that 75(95%confidence interval(CI):60,91)and 575(95%CI:535,615)liver-related deaths and new infections would occur by 2034,respectively.Launching an expanded treatment program,without screening interventions,would cause modest outcomes regarding CHC prevalence(16.6%reduction in 2034 compared to 2020)and liverrelated deaths(10 deaths would be prevented compared to the status quo scenario by 2034).Implementing a test and treat strategy among the general population but without any intervention in the PWID population would suffice to meet the mortality target but not the incidence target.To achieve HCV elimination in Cyprus,3080(95%CI:3000,3200)HCV patients need to be diagnosed and treated by 2034(2680 from the general population and 400 from PWID),and harm reduction coverage among PWID should be increased by 3%per year(from 25%in 2020 to 67%in 2034).CONCLUSION Elimination of HCV is a demanding public health strategy,which requires significant interventions both among the general population and high-risk groups.

基于AHP-TOPSIS的土壤重金属污染修复植物适宜性评价

目的筛选出适应性强、处理效果好的植物,用于解决困扰重金属污染土壤植物修复的选种难题。方法应用层次分析法构建以生态适应性、技术可行性、经济可行性为准则、下含8个影响因素的指标体系,建立判断矩阵,并对其构造进行改进,通过逼近理想解的排序法筛选出最适合的修复植物;把该模型用于沈阳市某化工厂被重金属严重污染的土壤修复,对15种植物进行评价、筛选。结果构造的改进判断矩阵评价误差更小;通过计算发现,在污染土壤植物修复工程中,耐旱性是影响修复效果的主要因素;筛选结果表明,狼尾草等适合用于该场地的植物修复,接近度为0.838,去除率可达82%。结论该植物筛选模型能综合考虑各评价指标的影响,可以客观、准确地筛选出修复植物。

筛分数学模型的发展现状及分析

筛分作业在散体物料处理工艺中具有极其重要的地位,筛面上细粒物料的透筛过程以概率论的原理为基础。综述了当前粒状物料的透筛概率模型,对业已提出的筛分数学模型进行了分类分析,认为筛分动力学模型较好地反映了筛分作业的实质,现有的筛分数学模型大都是对筛分结果的拟合而并不能反映筛分作业条件同工艺效果之间的关系。指出筛分数学模型的发展趋势将是以试验为基础,以计算机手段为依托,建立综合考虑物料物性及其相互作用的具有预测功能的动态过程模型。

筛分技术的研究现状及发展趋势

筛分作业是当前应用最广泛的物料按粒度分类方法,从筛面上物料的运动规律、透筛概率理论、潮湿物料深度筛分技术和筛分数学模型这4个方面回顾了筛分技术的发展概况,指出筛分基础理论尚处于假说和实验科学阶段而落后于生产实践。潮湿物料的深度筛分技术虽然有了很大进步,但筛分机械强度和筛分工艺效果之间存在着突出的矛盾。今后筛分理论的研究将以试验为基础,以计算机技术为依托,逐步建立综合考虑物料性质及其相互影响的物料运动模型和描述筛分过程数学模型。

煤用概率分级筛数学模型的建立

本文提出了研究筛分数学模型的方法,介绍了GS300×2000型煤用概率分级筛的半工业性试验系统。根据理论分析和试验结果,建立了煤用概率分级筛的数学模型。该模型采用分段函数比较完整地描述了概率筛分的分配曲线,模型预测精度较高,模型参数的物理意义明确。本文对煤用概率分级筛的参数优化及概率筛分过程的模拟有重要意义。

物料在抖动输送板上运动的计算机模拟与试验研究

对物料在抖动输送板上的运动进行分析，推出了物料运动特征界限值，建立数学模型并进行计算机模拟计算，非常直观地将振动方向角ε、板面角α与运动特征界限值Ｋ１、Ｋ２的关系用图线表示出来；同时用所研制的试验台进行试验验证，证明所建立的计算模型有实用价值，可以作为确定抖动输送板设计参数的参考和依据。

煤用概率分级筛数学模型的研究

通过平均触网概率的提出，首次建立了筛分机操作参数与筛分效果之间有着定量关系的煤用概率分级筛筛分数学模型。对该模型得到的理论预测值与实验实测值进行了对比检验，结果表明，该模型具有模型参数少、预测精度高、适用范围广的特点。

基于MATLAB/Simulink的粒度分离过程计算机仿真

以仿真振动筛分过程为例,采用先进的科学计算软件MATLAB/Simulink对粒度分离过程进行计算机仿真。建立了振动筛分过程仿真模型,介绍了仿真所用的数学模型及主要Simulink模块,并进行了筛分过程的计算机仿真。仿真结果与实测结果非常吻合,筛上产品、筛下产品的仿真值与实测值相对误差分别为-4.26%和1.09%。仿真实验表明振动筛分过程仿真模型准确地反映了其筛分过程,论证了采用MATLAB/Simulink对粒度分离过程进行计算机仿真的可行性。

胜利油田智能完井技术研究新进展

智能完井技术综合运用传感技术、信息技术和控制技术来提高油井产能、降低作业风险和费用,实现资源利用和油田开发效益的最大化,是现代完井技术的发展方向。简单介绍了国内外智能完井技术的研究现状,重点介绍了胜利油田智能完井技术的研究进展情况:目前已研制出整体性能与国外同类产品接近的高强管外封隔器,能达到现场要求的遇油遇水自膨胀管外封隔器;形成了均衡供液筛管分段完井技术和数据采集技术;建立了处理井下产液和压力数据的数学模型,根据处理结果可以判断出水层位。通过筛管分段完井数据采集模拟试验,对采用数学模型处理井下产液和压力数据判断出水层位的方法进行了验证,结果表明,该方法可行,可为现场采用筛管分段完井及判断控制井下出水层位提供理论依据。

风筛式清选装置清选性能试验研究

为了研究风筛式清选装置运动参数对清选性能的影响规律,在自行研制的清选试验台上进行小麦清选试验,利用DPS数据处理系统进行方差分析,并建立清洁率、损失率与贯流风机转速、离心风机转速、离心风机倾角及振动筛曲柄转速之间的数学模型,利用遗传算法进行多目标优化,获得优化参数组合的Pareto最优解集,并进行验证,为风筛式清选装置的设计及使用调整提供依据。

相控阵体制雷达精准自卫干扰技术

面对新一代相控阵体制雷达,采用传统的基于空域、时域、频域大范围"遮盖"自卫干扰,效率低,干扰效果受限,还带来电磁兼容、电磁暴露等问题。精准干扰是提升对相控阵体制雷达综合对抗效能的有效解决途径。文中对相控阵体制雷达精准自卫干扰技术开展了研究,分析了相控阵体制雷达精准自卫干扰系统设计的主要考虑因素,构建了相控阵体制雷达精准自卫干扰系统的系统架构,在此系统架构上建立了精准自卫干扰数学模型,并通过数字仿真验证了模型的有效性。

粮食筛选系统中双通道带通滤光膜的研制

利用杂质和劣质粮食与优质粮食的近红外吸收光谱不同的特性,根据光谱中反映测试成分的特征波段的差异对粮食进行光学分选.在光谱进入传感器之前经过滤光片对多个测试波段进行过滤,降低噪音的影响.本文针对光学筛选系统中核心部件双通道带通滤光片进行研制,从膜系设计理论出发,采用了Smith法结合膜系设计软件设计了以周期膜系和非周期膜系相结合的双通道带通滤光膜系,利用电子束蒸发和离子辅助沉积的方法进行制备并通过数学建模分析,减小了实验误差对光谱的影响.在1 200nm和1 450nm波段得到平均透射率大于97%,1 000~1 130nm和1 570~2 000nm波段平均透射率小于1%的滤光膜,通过系统测试,满足使用要求.

沥青搅拌设备振动筛防堵模型与试验研究

沥青混合料搅拌设备振动筛的筛分效率决定了混合料生产级配的稳定性,堵筛会使筛分效率发生变化。为了研究堵筛问题,通过对振动筛的结构、工作机理和运动特性分析,建立了振动筛的运动学模型,确定了振动参数与偏心块质量、振动筛质量、当量转动半径等参数之间关系;通过对堵筛条件下颗粒的运动特性和动力学分析,分别建立了刚性筛网和弹性筛网的力学模型,分析了振动筛的动力学参数、材料的物理特性、筛孔尺寸和筛网刚度等参数对堵筛的影响。实验结果表明,对5 mm×5 mm的刚性筛网方孔筛,在常规设计的振动筛频率16 Hz和振幅5 mm下堵筛率较大(大于10%),堵筛颗粒的逃逸能力较低。因此,当筛孔尺寸小于6mm时,需要提高振动强度改善堵筛率;为了避免提高振动参数增加技术难度或影响设备结构强度,采用刚度小的弹性筛网是最佳解决方案。

新型X射线影像增强系统分辨率数学模型

课题组设计了新型的X射线影像增强系统。由于它是由多个光电器件级联而成的链状成像系统,在组成器件之间存在着一定的分辨率函数关系,并且这种函数关系会随着成像视野的变化而变化。鉴于此种关系,建立了系统的分辨率数学模型,对多种器件组合效果进行理论分析。结果表明分辨率理论计算值和实验测量值比较吻合,所以分辨率数学模型节省了系统的设计时间和费用,对提高系统分辨率起着理论指导作用。

机场2阶段安检系统设计与性能分析

为提高机场安检效率,运用排队论和概率论,结合速度和准确性操作特性曲线,建立2阶段安检系统数学模型;根据实例数据进行分析,通过改变第一阶段安检速度与抽检比例,分析第一阶段、第2阶段以及整个2阶段安检系统的错误通过率、错误报警率、随身物品平均等待时间的变化情况。结果表明：在旅客到达率不变的情况下,第一阶段最大检测时间越长,整个安检系统的错误通过率与错误报警率越高,随身物品平均等待时间越短;当第一阶段最大检测时间超过5 s后,其对随身物品的平均等待时间影响很小;提高抽检比例,会使随身物品平均等待时间增加,使整个安检系统的错误报警率升高。