The application of dams built upstream will change the input conditions, including water and sediment, of downstream fluvial system, and destroy previous dynamic quasi-equilibrium reached by channel streamflow, so ind...The application of dams built upstream will change the input conditions, including water and sediment, of downstream fluvial system, and destroy previous dynamic quasi-equilibrium reached by channel streamflow, so indispensable adjustments are necessary for downstream channel to adapt to the new water and sediment supply, leading the fluvial system to restore its previous equilibrium or reach a new equilibrium. Using about 50-year-long hydrological, sedimentary and cross-sectional data, temporal response processes of Toudaoguai cross-section located in the upper Yellow River to the operation of reservoirs built upstream are analyzed. The results show that the Toudaoguai cross-section change was influenced strongly by upstream reservoir operation and downstream channel bed armoring thereafter occurred gradually and extended to the reach below Sanhuhekou gauging station. Besides, median diameter of suspended sediment load experienced a three-stage change that is characterized by an increase at first, then a decrease and an increase again finally, which reflects the process of channel bed armoring that began at Qingtongxia reservoir and then gradually developed downstream to the reach below Sanhuhekou cross-section. Since the joint operation strategy of Longyangxia, Liujiaxia and Qingtongxia reservoirs was introduced in 1986, the three-stage change trend has become less evident than that in the time period between 1969 and 1986 when only Qingtongxia and Liujiaxia reservoirs were put into operation alone. In addition, since 1987, the extent of lateral migration and thalweg elevation change at Toudaoguai cross-section has reduced dramatically, cross-sectional profile and location tended to be stable, which is beneficial to the normal living for local people.展开更多
Background Invasive cancer of the cervix is considered a preventable disease because it has a long pre-invasive state, cervical cytology screening programs are currently available, and treatment of pre-invasive lesion...Background Invasive cancer of the cervix is considered a preventable disease because it has a long pre-invasive state, cervical cytology screening programs are currently available, and treatment of pre-invasive lesions is effective. We tested the accuracy of frozen section examination （FSE） of cone specimens to identify the endocervical margin and rule out invasion in patients with high-grade cervical intraepithelial neoplasia （CIN）. Methods For 320 consecutive patients with a preoperative biopsy result of CIN stage 2/3, cold-knife conization （CKC） was performed followed by FSE. The results from analyses of permanent paraffin sections （PS） were compared with the FSE findings. Results The accuracy of FSE was 87% （278/320）. For all of the seven patients with an invasive squamous cell carcinoma of the cervix identified by FSE, the diagnosis was confirmed by PS analysis. For one patient, the FSE result was cervicitis, whereas PS ananlysis showed microinvasive carcinoma. Appropriate surgery was performed for all patients based on the FSE and biopsy results. The FSE and PS results were not significantly different （P=-0.000）. Definitive examination of margin status using PS was concordant with FSE findings in all cases. Conclusions FSE is a rapid and reliable method for evaluating CKC specimens. It can identify frank invasion, permit adequate treatment in a one-stage procedure, and reliably detect clear resection margins. Since discrepancies do exist and may result in inappropriate treatment, further research is required to decrease these discrepancies and avoid missing even one case.展开更多
基金National Natural Science Foundation of China, No.40771031 Thanks are expressed to the Yellow River Conservancy Commission and International Network on Erosion and Sedimentation for the permission of access to hydrometric data. We are also grateful to Dr. Wang Xiujie from Tianjin University for his generous help.
文摘The application of dams built upstream will change the input conditions, including water and sediment, of downstream fluvial system, and destroy previous dynamic quasi-equilibrium reached by channel streamflow, so indispensable adjustments are necessary for downstream channel to adapt to the new water and sediment supply, leading the fluvial system to restore its previous equilibrium or reach a new equilibrium. Using about 50-year-long hydrological, sedimentary and cross-sectional data, temporal response processes of Toudaoguai cross-section located in the upper Yellow River to the operation of reservoirs built upstream are analyzed. The results show that the Toudaoguai cross-section change was influenced strongly by upstream reservoir operation and downstream channel bed armoring thereafter occurred gradually and extended to the reach below Sanhuhekou gauging station. Besides, median diameter of suspended sediment load experienced a three-stage change that is characterized by an increase at first, then a decrease and an increase again finally, which reflects the process of channel bed armoring that began at Qingtongxia reservoir and then gradually developed downstream to the reach below Sanhuhekou cross-section. Since the joint operation strategy of Longyangxia, Liujiaxia and Qingtongxia reservoirs was introduced in 1986, the three-stage change trend has become less evident than that in the time period between 1969 and 1986 when only Qingtongxia and Liujiaxia reservoirs were put into operation alone. In addition, since 1987, the extent of lateral migration and thalweg elevation change at Toudaoguai cross-section has reduced dramatically, cross-sectional profile and location tended to be stable, which is beneficial to the normal living for local people.
文摘Background Invasive cancer of the cervix is considered a preventable disease because it has a long pre-invasive state, cervical cytology screening programs are currently available, and treatment of pre-invasive lesions is effective. We tested the accuracy of frozen section examination （FSE） of cone specimens to identify the endocervical margin and rule out invasion in patients with high-grade cervical intraepithelial neoplasia （CIN）. Methods For 320 consecutive patients with a preoperative biopsy result of CIN stage 2/3, cold-knife conization （CKC） was performed followed by FSE. The results from analyses of permanent paraffin sections （PS） were compared with the FSE findings. Results The accuracy of FSE was 87% （278/320）. For all of the seven patients with an invasive squamous cell carcinoma of the cervix identified by FSE, the diagnosis was confirmed by PS analysis. For one patient, the FSE result was cervicitis, whereas PS ananlysis showed microinvasive carcinoma. Appropriate surgery was performed for all patients based on the FSE and biopsy results. The FSE and PS results were not significantly different （P=-0.000）. Definitive examination of margin status using PS was concordant with FSE findings in all cases. Conclusions FSE is a rapid and reliable method for evaluating CKC specimens. It can identify frank invasion, permit adequate treatment in a one-stage procedure, and reliably detect clear resection margins. Since discrepancies do exist and may result in inappropriate treatment, further research is required to decrease these discrepancies and avoid missing even one case.
