In the sedimentary strata dating of estuarial coastal areas,it is often found that there is phenomenon of time-reversal in strata.The seabed sediments could be liquefied under storm waves.A laboratory wave flume exper...In the sedimentary strata dating of estuarial coastal areas,it is often found that there is phenomenon of time-reversal in strata.The seabed sediments could be liquefied under storm waves.A laboratory wave flume experiment demonstrated that storm-induced liquefaction deposits are formed by the oscillations of liquefied sediments.In this paper,the particle size distribution and ^(210)Pb_(ex) specific activity of the sediment samples from the liquefaction disturbed zone and adjacent stable zone of the Yellow River Delta were tested.The stratigraphic divisions based on storm liquefaction deposit sequence can effectively explain the vertical changes in particle size and ^(210)Pb_(ex) specific activity.Due to the differentiation of particles during the storm induced liquefaction,coarse and fine particles regrouped,which could explain the phenomenon of time-reversal in dating data.展开更多
目的通过与全视野数字化乳腺X线摄影(Full Field Digital Mammography,FFDM)对比,探讨数字乳腺断层重建的合成二维图像(Synthetic Mammography,SM)在诊断乳腺良恶性病变中的应用价值。方法回顾性分析我院153例乳腺良、恶性病变患者的FFD...目的通过与全视野数字化乳腺X线摄影(Full Field Digital Mammography,FFDM)对比,探讨数字乳腺断层重建的合成二维图像(Synthetic Mammography,SM)在诊断乳腺良恶性病变中的应用价值。方法回顾性分析我院153例乳腺良、恶性病变患者的FFDM与SM图像,比较2组图像病变可见性评级、影像征象、BI-RADS分类及平均腺体剂量,以病理结果为“金标准”,ROC曲线评估2组图像诊断效能。结果FFDM与SM病变可见性评级存在统计学差异,SM病变显示略优于FFDM(Z=-3.130,P=0.002);2组图像显示乳腺病变影像征象一致性较好,Kappa值为0.827~0.900;FFDM与SM诊断乳腺良恶性病变的曲线下面积分别为0.847(95CI%:0.774~0.921)和0.861(95CI%:0.789~0.933),差异无统计学意义(Z=-1.347,P=0.178);FFDM与SM的平均腺体剂量差异有统计学意义(P<0.001),SM+DBT平均腺体剂量相比FDM+DBT降低约45%(3.29/6.01)。结论SM与FFDM在乳腺良恶性病变诊断中的应用价值相当,SM可替代FFDM作为二维图像与DBT联合应用于乳腺病变检查,且没有增加辐射剂量。展开更多
基金funding for this project was provided by the National Natural Science Foundation of China (No.41976049)。
文摘In the sedimentary strata dating of estuarial coastal areas,it is often found that there is phenomenon of time-reversal in strata.The seabed sediments could be liquefied under storm waves.A laboratory wave flume experiment demonstrated that storm-induced liquefaction deposits are formed by the oscillations of liquefied sediments.In this paper,the particle size distribution and ^(210)Pb_(ex) specific activity of the sediment samples from the liquefaction disturbed zone and adjacent stable zone of the Yellow River Delta were tested.The stratigraphic divisions based on storm liquefaction deposit sequence can effectively explain the vertical changes in particle size and ^(210)Pb_(ex) specific activity.Due to the differentiation of particles during the storm induced liquefaction,coarse and fine particles regrouped,which could explain the phenomenon of time-reversal in dating data.
文摘目的通过与全视野数字化乳腺X线摄影(Full Field Digital Mammography,FFDM)对比,探讨数字乳腺断层重建的合成二维图像(Synthetic Mammography,SM)在诊断乳腺良恶性病变中的应用价值。方法回顾性分析我院153例乳腺良、恶性病变患者的FFDM与SM图像,比较2组图像病变可见性评级、影像征象、BI-RADS分类及平均腺体剂量,以病理结果为“金标准”,ROC曲线评估2组图像诊断效能。结果FFDM与SM病变可见性评级存在统计学差异,SM病变显示略优于FFDM(Z=-3.130,P=0.002);2组图像显示乳腺病变影像征象一致性较好,Kappa值为0.827~0.900;FFDM与SM诊断乳腺良恶性病变的曲线下面积分别为0.847(95CI%:0.774~0.921)和0.861(95CI%:0.789~0.933),差异无统计学意义(Z=-1.347,P=0.178);FFDM与SM的平均腺体剂量差异有统计学意义(P<0.001),SM+DBT平均腺体剂量相比FDM+DBT降低约45%(3.29/6.01)。结论SM与FFDM在乳腺良恶性病变诊断中的应用价值相当,SM可替代FFDM作为二维图像与DBT联合应用于乳腺病变检查,且没有增加辐射剂量。
