Colonoscopy techniques combining or replacing air insufflation with water infusion are becoming increasinglypopular.They were originally designed to reduce colonic spasms,facilitate cecal intubation,and lower patient ...Colonoscopy techniques combining or replacing air insufflation with water infusion are becoming increasinglypopular.They were originally designed to reduce colonic spasms,facilitate cecal intubation,and lower patient discomfort and the need for sedation.These maneuvers straighten the rectosigmoid colon and enable the colonoscope to be inserted deeply without causing looping of the colon.Water-immersion colonoscopy minimizes colonic distension and improves visibility by introducing a small amount of water.In addition,since pain during colonoscopy indicates risk of bowel perforation and sedation masks this important warning,this method has the potential to be the favored insertion technique because it promotes patient safety without sedation.Recently,this water-immersion method has not only been used for colonoscope insertion,but has also been applied to therapy for sigmoid volvulus,removal of lesions,lower gastrointestinal bleeding,and therapeutic diagnosis of abnormal bowel morphology and irritable bowel syndrome.Although a larger sample size and prospective head-to-head-designed studies will be needed,this review focuses on the usefulness of waterimmersion colonoscopy for diagnostic and therapeutic applications.展开更多
Profles of tidal current and suspended sediment concentration （SSC） were measured in the North Branch of the Changjiang Estuary from neap tide to spring tide in April 2010. The measurement data were analyzed to dete...Profles of tidal current and suspended sediment concentration （SSC） were measured in the North Branch of the Changjiang Estuary from neap tide to spring tide in April 2010. The measurement data were analyzed to determine the characteristics of intratidal and neap-spring variations of SSC and suspended sediment transport. Modulated by tidal range and current speed, the tidal mean SSC increased from 0.5 kg/m3 in neap tide to 3.5 kg/ma in spring tide. The intratidal variation of the depth-mean SSC can be summarized into three types： V-shape variation in neap tide, M-shape and mixed M-V shape variation in medium and spring tides. The occurrence of these variation types is controlled by the relative intensity and interaction of resuspension, settling and impact of water exchange from the rise and fall of tide. In neap tide the V-shape variation is mainly due to the dominant effect of the water exchange from the rise and fall of tide. During medium and spring tides, resuspension and settling processes become dominant. The interactions of these processes, together with the sustained high ebb current and shorter duration of low-tide slack, are respon- sible for the M-shape and M-V shape SSC variation. Weakly consolidated mud and high current speed cause significant resuspension and remarkable flood and ebb SSC peaks. Setting occurs at the slack water periods to cause SSC troughs and formation of a thin flufflayer on the bed. Fluxes of water and suspended sediment averaged over the neap-spring cycle are all seawards, but the magnitude and direction of tidal net sediment flux is highly variable.展开更多
文摘Colonoscopy techniques combining or replacing air insufflation with water infusion are becoming increasinglypopular.They were originally designed to reduce colonic spasms,facilitate cecal intubation,and lower patient discomfort and the need for sedation.These maneuvers straighten the rectosigmoid colon and enable the colonoscope to be inserted deeply without causing looping of the colon.Water-immersion colonoscopy minimizes colonic distension and improves visibility by introducing a small amount of water.In addition,since pain during colonoscopy indicates risk of bowel perforation and sedation masks this important warning,this method has the potential to be the favored insertion technique because it promotes patient safety without sedation.Recently,this water-immersion method has not only been used for colonoscope insertion,but has also been applied to therapy for sigmoid volvulus,removal of lesions,lower gastrointestinal bleeding,and therapeutic diagnosis of abnormal bowel morphology and irritable bowel syndrome.Although a larger sample size and prospective head-to-head-designed studies will be needed,this review focuses on the usefulness of waterimmersion colonoscopy for diagnostic and therapeutic applications.
基金The National Science Foundation of China under contract Nos 50939003 and 41176069the Foundation of State Key Laboratory of Estuarine and Coastal Research,East China Normal University of China under contract No.SKLEC-2012KYYW06
文摘Profles of tidal current and suspended sediment concentration （SSC） were measured in the North Branch of the Changjiang Estuary from neap tide to spring tide in April 2010. The measurement data were analyzed to determine the characteristics of intratidal and neap-spring variations of SSC and suspended sediment transport. Modulated by tidal range and current speed, the tidal mean SSC increased from 0.5 kg/m3 in neap tide to 3.5 kg/ma in spring tide. The intratidal variation of the depth-mean SSC can be summarized into three types： V-shape variation in neap tide, M-shape and mixed M-V shape variation in medium and spring tides. The occurrence of these variation types is controlled by the relative intensity and interaction of resuspension, settling and impact of water exchange from the rise and fall of tide. In neap tide the V-shape variation is mainly due to the dominant effect of the water exchange from the rise and fall of tide. During medium and spring tides, resuspension and settling processes become dominant. The interactions of these processes, together with the sustained high ebb current and shorter duration of low-tide slack, are respon- sible for the M-shape and M-V shape SSC variation. Weakly consolidated mud and high current speed cause significant resuspension and remarkable flood and ebb SSC peaks. Setting occurs at the slack water periods to cause SSC troughs and formation of a thin flufflayer on the bed. Fluxes of water and suspended sediment averaged over the neap-spring cycle are all seawards, but the magnitude and direction of tidal net sediment flux is highly variable.
