Numerical Integrators for Dispersion-Managed KdV Equation

In this paper, we consider the numerics of the dispersion-managed Korteweg-de Vries (DM-KdV) equation for describing wave propagations in inhomogeneous media. The DM-KdV equation contains a variable dispersion map with discontinuity, which makes the solution non-smooth in time. We formally analyze the convergence order reduction problems of some popular numerical methods including finite difference and time-splitting for solving the DM-KdV equation, where a necessary constraint on the time step has been identified. Then, two exponential-type dispersion-map integrators up to second order accuracy are derived, which are efficiently incorporated with the Fourier pseudospectral discretization in space, and they can converge regardless of the discontinuity and the step size. Numerical comparisons show the advantage of the proposed methods with the application to solitary wave dynamics and extension to the fast & strong dispersion-management regime.     

HIV/AIDS患者结核潜伏感染的影响因素研究

背景 结核病是导致人免疫缺陷病毒/获得性免疫缺陷综合征（HIV/AIDS）患者死亡的首要原因，而HIV感染也是导致结核潜伏感染（LTBI）发展为结核病的主要危险因素。因此，对HIV/AIDS患者进行LTBI筛查和治疗是预防该类人群结核病的发生从而减少其死亡的重要举措。 目的 对宁夏回族自治区银川市市区内HIV/AIDS患者进行LTBI筛查，并分析其影响因素，识别高危人群，为HIV/AIDS患者结核病的预防性治疗提供科学依据。 方法 选取2021年3—8月于宁夏回族自治区银川市市区内定点管理单位治疗的546例HIV/AIDS患者为研究对象。通过现场问卷调查及查阅患者管理档案的方式收集HIV/AIDS患者的一般资料，其中一般人口学特征包括性别、年龄、民族、学历、婚姻状况、家庭人均年收入、职业类型、体质指数（BMI）、吸烟情况、饮酒情况等；临床资料包括慢性病患病情况、与结核病患者密切接触情况、HIV/AIDS确诊时长、抗病毒治疗时长、合并其他感染情况、近期CD4+ T淋巴细胞计数（CD4）等。通过结核菌素皮肤试验（TST）对研究对象进行LTBI筛查，根据TST结果将546例HIV/AIDS患者分为非LTBI组（TST阴性413例）和LTBI组（TST阳性133例）。比较两组患者的一般资料，采用多因素Logistic回归分析探讨HIV/AIDS患者发生LTBI的影响因素，并利用R软件建立限制性立方样条模型拟合CD4与LTBI风险之间的量效关系。 结果 银川市市区内HIV/AIDS患者的TST阳性率为24.4%。已婚〔OR=0.544，95%CI（0.321，0.922），P<0.05〕是HIV/AIDS患者发生LTBI的保护因素；吸烟〔OR=1.919，95%CI（1.213，3.037），P<0.05〕、与结核病患者有过密切接触〔OR=11.100，95%CI（2.889，42.648），P<0.05〕是HIV/AIDS患者发生LTBI的危险因素。限制性立方样条模型拟合结果显示，HIV/AIDS患者的CD4与LTBI风险呈近似"n"形的非线性关系（非线性检验χ2=29.080，P<0.001）。 结论 应重点关注HIV/AIDS患者中未婚、吸烟、与结核病患者有过密切接触人群LTBI的发生情况，并及时进行预防性治疗；对于CD4较低的患者，建议采用多种方法进行LTBI筛查。     

Bayesian leveraging of historical control data for a clinical trial with time-to-event endpoint

The recent 21st Century Cures Act propagates innovations to accelerate the discovery, development, and delivery of 21st century cures. It includes the broader application of Bayesian statistics and the use of evidence from clinical expertise. An example of the latter is the use of trial-external (or historical) data, which promises more efficient or ethical trial designs. We propose a Bayesian meta-analytic approach to leverage historical data for time-to-event endpoints, which are common in oncology and cardiovascular diseases. The approach is based on a robust hierarchical model for piecewise exponential data. It allows for various degrees of between trial-heterogeneity and for leveraging individual as well as aggregate data. An ovarian carcinoma trial and a non-small cell cancer trial illustrate methodological and practical aspects of leveraging historical data for the analysis and design of time-to-event trials.     

疏肝化瘀益气法对肝纤维化大鼠HIF-1α、VEGF表达的影响

目的研究疏肝化瘀益气法干预肝纤维化大鼠模型过程中,对大鼠肝脏组织HIF-1α、VEGF表达的影响。方法采用无菌猪血清诱导大鼠肝纤维化模型。随机分为3组。空白组、模型组给予生理盐水灌胃;软肝散干预组自造模开始即给予软肝散生药水煎剂灌胃。采用HE染色和Masson染色观察肝组织纤维化程度,RT-PCR、Western bolt检测肝组织中HIF-1α、VEGF蛋白的表达情况。结果与模型组相比,软肝散干预组肝组织中HIF-1α、VEGF表达显著下调(P<0.05或P<0.01)。且随着干预给药时间的延长,其表达量逐渐降低。结论以疏肝化瘀益气法为指导的软肝散可以改善肝纤维化的病理改变,通过下调HIF-1α、VEGF表达,抑制HIF-1α、VEGF的过表达,调控HIF-1α/VEGF信号通路抑制肝组织纤维化进程,从而发挥抗纤维化的作用。     

Circumferential Resection Margin as a Hospital Quality Assessment Tool for Rectal Cancer Surgery

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Unique sleep‐stage transitions determined by obstructive sleep apnea severity,age and gender

In obstructive sleep apnea, patients’ sleep is fragmented leading to excessive daytime sleepiness and co‐morbidities like arterial hypertension. However, traditional metrics are not always directly correlated with daytime sleepiness, and the association between traditional sleep quality metrics like sleep duration and arterial hypertension is still ambiguous. In a development cohort, we analysed hypnograms from mild (n = 209), moderate (n = 222) and severe (n = 272) obstructive sleep apnea patients as well as healthy controls (n = 105) from the European Sleep Apnea Database. We assessed sleep by the analysis of two‐step transitions depending on obstructive sleep apnea severity and anthropometric factors. Two‐step transition patterns were examined for an association to arterial hypertension or daytime sleepiness. We also tested cumulative distributions of wake as well as sleep‐states for power‐laws (exponent α) and exponential distributions (decay time τ) in dependency on obstructive sleep apnea severity and potential confounders. Independent of obstructive sleep apnea severity and potential confounders, wake‐state durations followed a power‐law distribution, while sleep‐state durations were characterized by an exponential distribution. Sleep‐stage transitions are influenced by obstructive sleep apnea severity, age and gender. N2 → N3 → wake transitions were associated with high diastolic blood pressure. We observed higher frequencies of alternating (symmetric) patterns (e.g. N2 → N1 → N2, N2 → wake → N2) in sleepy patients both in the development cohort and in a validation cohort (n = 425). In conclusion, effects of obstructive sleep apnea severity and potential confounders on sleep architecture are small, but transition patterns still link sleep fragmentation directly to obstructive sleep apnea‐related clinical outcomes like arterial hypertension and daytime sleepiness.     

基于限制性立方样条模型分析中老年人群空腹血糖受损与体质指数的关系

目的:调查重庆地区中老年人群空腹血糖(fasting blood-glucose,FBG)水平,分析空腹血糖受损(impaired fasting glu-cose,IFG)相关的危险因素,为糖尿病的防控提供依据.方法:回顾性分析2019年1至12月在重庆医科大学附属第一医院进行体检的中老年人群,收集空腹血糖FBG及相关生理生化指标,应用logistic回归模型结合限制性立方样条模型(restricted cubic splines,RCS)分析IFG与体质指数(body mass index,BMI)的剂量-反应关系.结果:44525名体检者共检出3913例IFG,检出率为8.79％,其中男性检出率为10.71％;女性检出率为6.84％ (P＜0.001).将研究对象分为正常血糖(normal glucose tolerance,NGT)组和IFG组,2组在性别、年龄、BMI、腰围(waist circumference,wC)、收缩压(systolic blood pressure,SBP)、舒张压(diastolic blood pressure,DBP)、高密度脂蛋白(high density lipoprotein-cholesterol,HDL-C)、低密度脂蛋白(low density lipoprotein-choles-terol,LDL-C)、总胆固醇(total cholesterol,TC)、甘油三酯(triacylglycerol,TG)、尿酸(uric acid,UA)水平差异均有统计学差异(P＜0.001).调整混杂因素之后,超重组(OR=1.178,95％CI=1.074～1.293)、肥胖组(OR=1.350,95％CI=1.157～1.574)与IFG关系具有统计学意义.RCS结果显示,男性、40～岁、50～岁、BMI连续变化与IFG关联呈非线性剂量-反应关系.结论:超重和肥胖是IFG剂量依赖性的危险因素,随着BMI升高,发生IFG的危险性随之升高.     

基于微区域PM2.5浓度卡尔曼插值预测模型的研究

目前颗粒物(尤其是PM2.5)污染问题日趋严重,人们对其关注度越来越高。本文提出一种结合三次样条插值方法的卡尔曼预测模型并将其应用于微区域校园环境PM2.5浓度的预测,以及实现PM2.5浓度的插值模拟图,模拟PM2.5的空间分布。本文实验基于实验室已搭建的环境信息监测系统服务器数据,其PM2.5浓度数据预测值和实际值通过Wilcoxon带符号秩检验后,双侧渐进显著性概率为0.527,远大于显著性水平α=0.05。同时,与神经网络模型预测方法(BP预测)和支持向量机预测方法(SVM预测)对比,卡尔曼预测模型的结果更理想,其日均值PM2.5浓度数据预测值和监测值的平均绝对误差(MEA)为1.8μg/m3,平均相对误差(MER)为6%,相关系数R为0.87。实验结果表明:卡尔曼预测模型能有效地用于PM2.5浓度预测,结合样条插值方法可以较好地模拟PM2.5的空间分布及局部污染特征。     

County-Level Contextual Characteristics and Disparities in Life Expectancy

ObjectiveTo estimate the contribution of county-level contextual factors to differences in life expectancy in the United States.MethodsWe used a counterfactual approach to estimate the years of life expectancy lost associated with 45 potentially modifiable county-level contextual characteristics in the United States in the year 2016. Contextual data and life expectancy data were obtained from the County Health Ranking Project and the U.S. Small-Area Life Expectancy Estimates Project, respectively.ResultsMedian census-tract–level life expectancy was 78.90 (interquartile range, 76.30-81.00) years, and the range across census tracts spanned 41.20 years. Large variations in life expectancy existed within and between states and within and between counties; the gap between counties was 20.30 years and gaps within counties ranged from 0 to 34.60 years. An array of 45 county-level factors was associated with 4.30 years of life expectancy loss. County-level adult smoking, food insecurity, adult obesity, physical inactivity, college education, and median household income were associated with 1.24-, 0.89-, 0.58-, 0.35-, 0.33-, and 0.14-year losses in life expectancy, respectively; and altogether were associated with a 3.53-year loss in life expectancy. The contribution of contextual factors to years of life expectancy lost varied among states and was more pronounced in states with lower life expectancy and in areas of increased socioeconomic deprivation and increased percentage of Black race.ConclusionSubstantial geographic variation in life expectancy was observed. Six county-level contextual factors were associated with a 3.53-year loss in life expectancy. The findings may inform and help prioritize approaches to reduce inequalities in life expectancy in the United States.     

Consanguinity and Late Fertility: Spatial Analysis Reveals Positive Association Patterns

The role of consanguinity on human complex traits is an important and controversial issue. In this work we focused on the Sardinian population and examined the effect of consanguineous unions on late female fertility. During the last century the island has been characterized by a high incidence of marriages between relatives, favoured by socio economic conditions and geographical isolation, and by high fertility despite a widespread tendency to delay reproduction. Through spatial analysis techniques, we explored the geographical heterogeneity of consanguinity and late fertility, and identified in Central–Eastern Sardinia a common area with an excess of both traits, where the traits are positively associated. We found that their association did not significantly affect women's fertility in the area, despite the expected negative role of both traits. Intriguingly, this critical zone corresponds well to areas reported by previous studies as being peculiar for a high frequency of centenarians and for lower risk in pregnancy outcome. The proposed approach can be generally exploited to identify target populations on which socioeconomic, biodemographic and genetic data can be collected at the individual level, and deeper analyses carried out to disentangle the determinants of complex biological traits and to investigate their association.