目的:了解浙江省6~15岁儿童抗麻疹病毒高浓度抗体阳性率及其影响因素,为制订麻疹防控策略提供科学依据。方法:采集浙江省湖州市长兴县和丽水市莲都区2069名6~15岁儿童的血清,ELISA法定量检测麻疹Ig G抗体水平,抗体浓度800 m IU/m L以上...目的:了解浙江省6~15岁儿童抗麻疹病毒高浓度抗体阳性率及其影响因素,为制订麻疹防控策略提供科学依据。方法:采集浙江省湖州市长兴县和丽水市莲都区2069名6~15岁儿童的血清,ELISA法定量检测麻疹Ig G抗体水平,抗体浓度800 m IU/m L以上为达到高浓度抗体。利用χ2检验或趋势χ2检验比较不同特征人群麻疹高浓度抗体的阳性率;多因素logistic回归分析麻疹疫苗接种儿童麻疹高浓度抗体的影响因素。结果:2069名调查对象中,麻疹高浓度抗体阳性率为36.06%(746/2069)。多因素logistic回归分析结果显示,年龄和起始接种月龄是麻疹疫苗接种儿童麻疹高浓度抗体的影响因素。随着年龄的增长,高浓度抗体阳性率呈现下降趋势(OR:0.866,95%CI:0.830~0.904,P<0.01);12月龄及以上接种者的高浓度抗体阳性率高于8月龄接种者(OR:0.633,95%CI:0.498~0.805,P<0.01)。结论:为维持高水平人群免疫屏障,建议疫情低发地区可以适当延迟麻疹疫苗首剂次接种时间,并对于大龄儿童适时进行补种。展开更多
Based on the nonlinear Mohr-Coulomb failure criterion and an associated flow rule,a kinematic admissible velocity field of failure mechanism of the 2-layer soil above a shallow horizontal strip anchor plate is constru...Based on the nonlinear Mohr-Coulomb failure criterion and an associated flow rule,a kinematic admissible velocity field of failure mechanism of the 2-layer soil above a shallow horizontal strip anchor plate is constructed.The ultimate pull-out force and its corresponding failure mechanism through the upper bound limit analysis according to a variation principle are deduced.When the 2-layer overlying soil is degraded into single-layer soil,the model of ultimate pullout force could also be degraded into the model of single-layer soil.And the comparison between results of single-layer soil variation method and those calculated by rigid limit analysis method proves the correctness of our method.Based on that,the influence of changes of geotechnical parameters on ultimate pullout forces and failure mechanism of a shallow horizontal strip anchor with the 2-layer soil above are analyzed.The results show that the ultimate pull-out force and failure mechanism of a shallow horizontal strip anchor with the 2-layer soil above are affected by the nonlinear geotechnical parameters greatly.Thus,it is very important to obtain the accurate geotechnical parameters of 2-layer soil for the evaluation of the ultimate pullout capacity of the anchor plate.展开更多
The strength of cement-based materials,such as mortar,concrete and cement paste backfill(CPB),depends on its microstructures(e.g.pore structure and arrangement of particles and skeleton).Numerous studies on the relati...The strength of cement-based materials,such as mortar,concrete and cement paste backfill(CPB),depends on its microstructures(e.g.pore structure and arrangement of particles and skeleton).Numerous studies on the relationship between strength and pore structure(e.g.,pore size and its distribution)were performed,but the micro-morphology characteristics have been rarely concerned.Texture describing the surface properties of the sample is a global feature,which is an effective way to quantify the micro-morphological properties.In statistical analysis,GLCM features and Tamura texture are the most representative methods for characterizing the texture features.The mechanical strength and section image of the backfill sample prepared from three different solid concentrations of paste were obtained by uniaxial compressive strength test and scanning electron microscope,respectively.The texture features of different SEM images were calculated based on image analysis technology,and then the correlation between these parameters and the strength was analyzed.It was proved that the method is effective in the quantitative analysis on the micro-morphology characteristics of CPB.There is a significant correlation between the texture features and the unconfined compressive strength,and the prediction of strength is feasible using texture parameters of the CPB microstructure.展开更多
文摘目的:了解浙江省6~15岁儿童抗麻疹病毒高浓度抗体阳性率及其影响因素,为制订麻疹防控策略提供科学依据。方法:采集浙江省湖州市长兴县和丽水市莲都区2069名6~15岁儿童的血清,ELISA法定量检测麻疹Ig G抗体水平,抗体浓度800 m IU/m L以上为达到高浓度抗体。利用χ2检验或趋势χ2检验比较不同特征人群麻疹高浓度抗体的阳性率;多因素logistic回归分析麻疹疫苗接种儿童麻疹高浓度抗体的影响因素。结果:2069名调查对象中,麻疹高浓度抗体阳性率为36.06%(746/2069)。多因素logistic回归分析结果显示,年龄和起始接种月龄是麻疹疫苗接种儿童麻疹高浓度抗体的影响因素。随着年龄的增长,高浓度抗体阳性率呈现下降趋势(OR:0.866,95%CI:0.830~0.904,P<0.01);12月龄及以上接种者的高浓度抗体阳性率高于8月龄接种者(OR:0.633,95%CI:0.498~0.805,P<0.01)。结论:为维持高水平人群免疫屏障,建议疫情低发地区可以适当延迟麻疹疫苗首剂次接种时间,并对于大龄儿童适时进行补种。
基金Project (51478477) supported by the National Natural Science Foundation of ChinaProject (2016CX012) supported by the Innovation-Driven Project of Central South University,ChinaProject (2014122006) supported by the Guizhou Provincial Department of Transportation Foundation,China
文摘Based on the nonlinear Mohr-Coulomb failure criterion and an associated flow rule,a kinematic admissible velocity field of failure mechanism of the 2-layer soil above a shallow horizontal strip anchor plate is constructed.The ultimate pull-out force and its corresponding failure mechanism through the upper bound limit analysis according to a variation principle are deduced.When the 2-layer overlying soil is degraded into single-layer soil,the model of ultimate pullout force could also be degraded into the model of single-layer soil.And the comparison between results of single-layer soil variation method and those calculated by rigid limit analysis method proves the correctness of our method.Based on that,the influence of changes of geotechnical parameters on ultimate pullout forces and failure mechanism of a shallow horizontal strip anchor with the 2-layer soil above are analyzed.The results show that the ultimate pull-out force and failure mechanism of a shallow horizontal strip anchor with the 2-layer soil above are affected by the nonlinear geotechnical parameters greatly.Thus,it is very important to obtain the accurate geotechnical parameters of 2-layer soil for the evaluation of the ultimate pullout capacity of the anchor plate.
基金Project(51722401)supported by the National Natural Science Foundation for Excellent Young Scholars of ChinaProject(FRF-TP-18-003C1)supported by the Fundamental Research Funds for the Central Universities,ChinaProject(51734001)supported by the Key Program of National Natural Science Foundation of China
文摘The strength of cement-based materials,such as mortar,concrete and cement paste backfill(CPB),depends on its microstructures(e.g.pore structure and arrangement of particles and skeleton).Numerous studies on the relationship between strength and pore structure(e.g.,pore size and its distribution)were performed,but the micro-morphology characteristics have been rarely concerned.Texture describing the surface properties of the sample is a global feature,which is an effective way to quantify the micro-morphological properties.In statistical analysis,GLCM features and Tamura texture are the most representative methods for characterizing the texture features.The mechanical strength and section image of the backfill sample prepared from three different solid concentrations of paste were obtained by uniaxial compressive strength test and scanning electron microscope,respectively.The texture features of different SEM images were calculated based on image analysis technology,and then the correlation between these parameters and the strength was analyzed.It was proved that the method is effective in the quantitative analysis on the micro-morphology characteristics of CPB.There is a significant correlation between the texture features and the unconfined compressive strength,and the prediction of strength is feasible using texture parameters of the CPB microstructure.
