Predicting the dynamic effects of rubella vaccination programmes

In the Netherlands, prepubertal girls have been vaccinated against rubella since 1974 (the UK strategy). Recently the Dutch Health Council advocated the introduction of an elimination strategy: vaccination of 1- and 9-year-old children. Dynamic effects of both strategies are studied using deterministic and stochastic models. Estimates of several epidemiological parameters are given. All computations and simulations were performed using as much field data as possible. Under the old strategy a new equilibrium is expected around the years 1995 to 2000; the new strategy is estimated to eliminate rubella (CRS) in large parts of the population 3 to 5 years after its initiation. Possible consequences of the new strategy on a cluster of people who refuse vaccination are investigated.     

三次抛物线配合方法在碘缺乏病区居民患病率分析中的应用

<正>在碘缺乏病区,居民甲状腺肿患病率在年鹅分布上的特征,可用二次抛物线加以描述[l].根握资料类型的不同,可选择更为适合的三次抛物线来描述.根据现场调查资料,本文采用三次抛物线方法进行配合,并将配合结果与二     

Neural networks in the study of the brain

Neural networks are models of the brain and have been used within Artificial Intelligence to provide alternative explanations to the symbolic explanations of cognition in which one assumes that an intelligent system has certain explicit representations of some aspect of the world and uses these in intelligent behavior. Obviously, if neural networks are indeed good models of the brain, and give a satisfactory account of cognition, then they could be a valuable tool to neuroscientists. This article gives a brief overview of the various neural network models, and critically reviews their status as models of the brain and of cognition.     

基于OBE理念的“医用数学建模”教学设计与实践

目的 基于成果导向教育（outcomes-based education,OBE）理念,以提升学员医用数学建模能力为目标,围绕《医用高等数学》课程中医用数学建模模块进行教学设计与实践并明确改进方向。方法 以“传染病模型”为例,进行教学实践;随后利用问卷方式收集44位学员反馈意见。综合运用统计描述、Mann-Whitney U检验、单因素方差分析和Scheffe法,以及卡方检验和z-检验对数据进行分析。结果 90.91%的学员对课程主题感兴趣,65.91%的学员认为该模式明显提升了学习效果。本次课程中学员学习主动性在对课程主题有、无兴趣这两个水平上无显著差异,而对知识点掌握程度和继续开展翻转课堂的意愿却有显著影响。结论 教学模式总体有效,但需在“突出建模,淡化计算”、提升学员参与度和强化课堂学习效果3个方面进一步改进。     

中国肥厚型心肌病患者血栓栓塞事件风险预测模型的构建研究

背景 血栓栓塞（TE）事件是肥厚型心肌病（HCM）的重要并发症。目前针对HCM患者TE事件的风险预测,仅国外学者构建了两个模型：HCM Risk-CVA及French HCM score,然而,现有研究发现HCM Risk-CVA模型对于中国HCM患者的临床价值较为有限。目的 本研究拟构建适合中国HCM患者的TE事件风险预测模型。方法本研究系回顾性队列研究,收集2010—2018年在四川大学华西医院就诊的537例HCM患者的病例资料。本研究通过电话随访或电子病历系统查询患者就诊记录,每6～12个月随访1次,直至出现终点事件或死亡或研究拟定的评估日期（2019-12-31）,终点事件定义为复合性TE事件。采用单因素和多因素Cox回归分析构建风险预测模型,并使用自助重抽样的方法进行内部验证。结果 537例患者中,24例患者有不同程度的数据缺失,最终纳入513例患者。中位随访时间为4.2(1.3,6.2)年,随访过程中42例（8.18%）发生TE事件,年发病率为2.10%[95%CI(1.47%,2.73%)]。根据多因素Cox回归模型构建TE事件风险预测模型,最终纳入年龄、既往TE事件、心...     

妊娠早期女性非稳态负荷水平与抑郁的相关性研究

背景 已知慢性应激与抑郁发生相关,非稳态负荷（AL）作为评估机体慢性应激反应的综合生理指标可能在抑郁的发生过程中起着重要作用。目的 探讨妊娠早期女性AL水平与抑郁的关系。方法 采用便利抽样法,选取2021年11月—2022年6月于中国人民解放军联勤保障部队第901医院、六安市金安区妇幼保健院产检的630例妊娠早期女性为研究对象,根据有无抑郁分为抑郁组（n=162）和非抑郁组（n=468）。采用一般资料调查表、妊娠相关焦虑量表、爱丁堡产后抑郁量表进行问卷调查,通过体格检查和实验室检查收集AL相关数据。采用多因素Logistic回归模型分析妊娠早期女性AL与抑郁的相关性。结果 630例妊娠早期女性抑郁发生率为25.7%(162/630)。低水平AL(AL<3分)孕妇427例（67.8%）,高水平AL(AL≥3分)孕妇203例（32.2%）。多因素Logistic回归分析显示,高水平AL是妊娠早期女性抑郁的危险因素[OR=1.651,95%CI(1.096,2.489),P<0.05]。结论 妊娠早期女性AL与抑郁存在正向关联,高水平AL会增加抑郁的发生风险。     

Neurobiological structure of the revised limit cycle reciprocal interaction model of REM cycle control

SUMMARY  New data bearing on the neurobiological basis of REM sleep and on mechanisms of EEG synchronization/desynchronization are presented. The revision of the limit cycle reciprocal interaction model (LCRIM) of REM cycle control incorporates new information on monoamine inhibition of mesopontine cholinergic neurons and of cholinergic mechanisms promoting REM sleep. New data also show cortical slow-wave activity is controlled by thalamocortical neurons' membrane potential level, which, in turn, is strongly controlled during sleep by brainstem cholinergic input arising from REM-on neurons. This new knowledge leads to a neurobiologi-cally justified integration of the LCRIM and of the two-process model of sleep control.     

Genetic and Environmental Causes of Tracking in Explosive Strength during Adolescence

Purpose: To determine whether the observed phenotypic stability in explosive strength during adolescence, as measured by inter-age correlations in vertical jump (VTJ), is mainly caused by genetic and/or environmental factors. Methods: Subjects are from the Leuven Longitudinal Twin Study (LLTS) (n = 105 pairs, equally divided over five zygosity groups). VTJ data were aligned on age at peak height velocity (APHV) to attenuate the temporal fluctuations in inter-age correlations caused by differences in timing of the adolescent growth spurt. Simplex models were fitted using structural equation modelling. Results: After aligning the data on APHV, the annual inter-age correlations show a clear simplex structure over a 4 year interval. The best fitting models included additive genetic and unique environmental sources of variation. Heritability estimates ranged between 60.8% (CI 37.7%–77.2%) and 87.3% (CI 74.2%–94.0%) for boys and between 76.5% (CI 56.7%–89.0%) and 88.6% (CI 77.8%–94.1%) for girls. Up to 56.4% and 62.8% of the total variation at the last measurement occasion is explained by additive genetic factors that already explained a significant amount of variation at previous measurement occasions in boys and girls respectively. It thus can be concluded that the observed stability of explosive strength during adolescence is mainly caused by a stable genetic influence in boys and girls. Conclusions: Additive genetic factors seem to be the main cause of the observed phenotypic stability in VTJ performance in boys and girls during adolescence.     

Comparing non-hierarchical models: Application to non-linear mixed effects modeling

There is no method available to compare the fit of two non-hierarchical non-linear mixed effects models, although the common practice is to select the model with the lower objective function. Bootstrapping the log-likelihood differences (LLDs) of non-hierarchical models and constructing a bootstrap confidence interval on the LLDs is proposed for comparing the goodness-of-fit of such models. This is illustrated with different parameterizations of clearance models for an anti-infective agent in a longitudinal pharmacokinetic study which are compared. Additive and exponential models of creatinine clearance as a predictor of clearance are used as examples.     

Mouse mammary tumor virus and mammary tumorigenesis in wild mice

The current knowledge of the distribution of the mouse mammary tumor virus (MMTV) proviral genomes and the mechanism of mammary tumorigenesis by MMTV in mice, with the main emphasis on Asian feral mice, is reviewed. The relevant earlier discoveries on the mode of MMTV transmission are summarized to provide an outline of the biology of MMTV. Finally, the viral etiology of human breast cancer will be discussed.