The objective of this systematic review was to assess tooth wear against ceramic crowns in posterior region in vitro and in vivo. An electronic PubMed search was conducted to identify studies on tooth wear against cer...The objective of this systematic review was to assess tooth wear against ceramic crowns in posterior region in vitro and in vivo. An electronic PubMed search was conducted to identify studies on tooth wear against ceramic crowns in posterior region. The selected studies were analyzed in regard to type of crowns, natural antagonist, measuring protocol and outcome. From a yield of 1 000 titles, 43 articles were selected for full-text analysis; finally, no in vitro and only five in vivo studies met the inclusion criteria. As there is heterogeneity in design, used measuring method, ceramics and analysis-form, a meta-analysis was not possible. Results of these studies are very controversial which makes a scientifically valid comparison impossible. This review indicated that some all-ceramic crowns are as wear friendly as metal-ceramic crowns. Up to now, it has been impossible to associate tooth wear with any specific causal agent. The role of ceramic surface treatment that might be responsible for the changing in rate of tooth wear seems undetermined as yet through clinical trials. The literature reveals that studies on this topic are subject to a substantial amount of bias. Therefore, additional clinical studies, properly designed to diminish bias, are warranted.展开更多
【目的】叶绿素含量可以用来评价棉花的长势情况,快速、准确和大面积监测棉花叶绿素含量,有助于实现精准农业。【方法】分别用0~2阶(步长为0.2)的分数阶微分处理和1~10尺度下的小波变换对田间测定的陆地棉和海岛棉等2种棉花的高光谱反...【目的】叶绿素含量可以用来评价棉花的长势情况,快速、准确和大面积监测棉花叶绿素含量,有助于实现精准农业。【方法】分别用0~2阶(步长为0.2)的分数阶微分处理和1~10尺度下的小波变换对田间测定的陆地棉和海岛棉等2种棉花的高光谱反射率进行处理,提高棉花叶绿素含量反演精度。通过分析不同处理方式的光谱与叶绿素含量之间的相关性,筛选得出敏感波段;并运用支持向量机回归和随机森林回归模型分别构建棉花叶绿素含量高光谱估算模型。【结果】(1)在全波段范围内,2种棉花325~1075 nm光谱反射率曲线整体变化趋势基本相同,其反射率均随着叶绿素含量的增加而增大。(2)经连续小波变换和分数阶微分变换后,2种棉花高光谱数据和叶绿素含量的相关性有所增强。使用随机森林回归和小波能量系数7对陆地棉叶绿素含量的反演效果最好,建模集决定系数(coefficient of determination,R^(2))为0.931,均方根误差(root mean square error,RMSE)为0.782,剩余预测偏差(residual prediction deviation,RPD)为2.162;使用随机森林回归和小波能量系数6对海岛棉叶绿素含量的反演效果最佳,建模集R^(2)为0.932,RMSE为1.198,RPD为2.687。【结论】本研究可为棉花叶绿素含量遥感估算提供技术参考。展开更多
The research results showed that the mean height, DBH , the individual volume and the growing stock of 4 5 year old Eucalyptus plantation decreased with the Continuous Planting Rotation(CPR)increasing. The mean tree h...The research results showed that the mean height, DBH , the individual volume and the growing stock of 4 5 year old Eucalyptus plantation decreased with the Continuous Planting Rotation(CPR)increasing. The mean tree height of the second, the third and the fourth rotation decreased by 7 4%, 7 9% and 20 0% respectively compared with the first rotation; the mean DBH decreased by 8 4%, 15 9% and 25 8% respectively; the individual volume decreased by 20 4%,32 8% and 50 4% respectively; and the growing stock decreased by 20 9%,38 7% and 50 5%; The changes of height, DBH , the individual volume and the growing stock with CPR increasing may be simulated by linear, parabola and exponential model: (1) y=a+bx; (2)y=a+bx+cx 2; (3)y=ax b. The corwn length and volume decreased with the CPR increasing, which indicated that the more CPR increased, the worse the growth poentials became, and in which the leaf biomass of the second, the third and the fourth rotation decreased by 10 2%, 44 7% and 71 0% respectively compared with the first planting rotation. Their changes with rotations accorded with the linear model. There was a significat multiple linear regression relationship between the parameter of crown structure and the standing growth index.展开更多
文摘The objective of this systematic review was to assess tooth wear against ceramic crowns in posterior region in vitro and in vivo. An electronic PubMed search was conducted to identify studies on tooth wear against ceramic crowns in posterior region. The selected studies were analyzed in regard to type of crowns, natural antagonist, measuring protocol and outcome. From a yield of 1 000 titles, 43 articles were selected for full-text analysis; finally, no in vitro and only five in vivo studies met the inclusion criteria. As there is heterogeneity in design, used measuring method, ceramics and analysis-form, a meta-analysis was not possible. Results of these studies are very controversial which makes a scientifically valid comparison impossible. This review indicated that some all-ceramic crowns are as wear friendly as metal-ceramic crowns. Up to now, it has been impossible to associate tooth wear with any specific causal agent. The role of ceramic surface treatment that might be responsible for the changing in rate of tooth wear seems undetermined as yet through clinical trials. The literature reveals that studies on this topic are subject to a substantial amount of bias. Therefore, additional clinical studies, properly designed to diminish bias, are warranted.
文摘【目的】叶绿素含量可以用来评价棉花的长势情况,快速、准确和大面积监测棉花叶绿素含量,有助于实现精准农业。【方法】分别用0~2阶(步长为0.2)的分数阶微分处理和1~10尺度下的小波变换对田间测定的陆地棉和海岛棉等2种棉花的高光谱反射率进行处理,提高棉花叶绿素含量反演精度。通过分析不同处理方式的光谱与叶绿素含量之间的相关性,筛选得出敏感波段;并运用支持向量机回归和随机森林回归模型分别构建棉花叶绿素含量高光谱估算模型。【结果】(1)在全波段范围内,2种棉花325~1075 nm光谱反射率曲线整体变化趋势基本相同,其反射率均随着叶绿素含量的增加而增大。(2)经连续小波变换和分数阶微分变换后,2种棉花高光谱数据和叶绿素含量的相关性有所增强。使用随机森林回归和小波能量系数7对陆地棉叶绿素含量的反演效果最好,建模集决定系数(coefficient of determination,R^(2))为0.931,均方根误差(root mean square error,RMSE)为0.782,剩余预测偏差(residual prediction deviation,RPD)为2.162;使用随机森林回归和小波能量系数6对海岛棉叶绿素含量的反演效果最佳,建模集R^(2)为0.932,RMSE为1.198,RPD为2.687。【结论】本研究可为棉花叶绿素含量遥感估算提供技术参考。
文摘The research results showed that the mean height, DBH , the individual volume and the growing stock of 4 5 year old Eucalyptus plantation decreased with the Continuous Planting Rotation(CPR)increasing. The mean tree height of the second, the third and the fourth rotation decreased by 7 4%, 7 9% and 20 0% respectively compared with the first rotation; the mean DBH decreased by 8 4%, 15 9% and 25 8% respectively; the individual volume decreased by 20 4%,32 8% and 50 4% respectively; and the growing stock decreased by 20 9%,38 7% and 50 5%; The changes of height, DBH , the individual volume and the growing stock with CPR increasing may be simulated by linear, parabola and exponential model: (1) y=a+bx; (2)y=a+bx+cx 2; (3)y=ax b. The corwn length and volume decreased with the CPR increasing, which indicated that the more CPR increased, the worse the growth poentials became, and in which the leaf biomass of the second, the third and the fourth rotation decreased by 10 2%, 44 7% and 71 0% respectively compared with the first planting rotation. Their changes with rotations accorded with the linear model. There was a significat multiple linear regression relationship between the parameter of crown structure and the standing growth index.
