By using the dataset of CMA-STI Tropical Cyclone Optimal Tracks, NCEP/NCAR reanalysis and intensive surface observations, a study is performed of the influences of a low-latitude monsoon surge on the longer persistenc...By using the dataset of CMA-STI Tropical Cyclone Optimal Tracks, NCEP/NCAR reanalysis and intensive surface observations, a study is performed of the influences of a low-latitude monsoon surge on the longer persistence and increase in torrential rains from the landing tropical storm Bilis. Results suggest that the southwest monsoon was anomalously active after Bilis came ashore. The westerly winds in Bilis's south side might give rise to the poleward movement of the SW monsoon, thus enlarging the pressure gradient between Bilis and the anticyclonic circulation to the south with the result of greatly intensified SW monsoon, which fueled plentiful water vapor, heat and momentum into the declining Bilis and allowed its long stay over land instead of erosion and disappearance. Before Bilis's landfall, the 2006 East Asian monsoon surge, characterized by the atmospheric ISO, experienced remarkable northward propagation. After landfall, the strong surge and powerful low frequency vapor convergence were just on the south side of Bilis, resulting in sharply increased rainfall. In addition, a broad belt of high-valued vapor fluxes extended from the eastern Arabian Sea via the Bay of Bengal, Indochina Peninsula and the South China Sea into the south of China. The belt was linked with the SW monsoon surge forming a moist tongue stretching from the Bay of Bengal to the south of China, which supplied continuously abundant vapor for Bilis along with the surge propagating poleward.展开更多
The NCEP/NCAR reanalysis, Japan Meteorological Agency(JMA) tropical cyclone tracks and intensive surface observations are used to diagnose the features of moisture transport of tropical storm Bilis(No. 0604), which is...The NCEP/NCAR reanalysis, Japan Meteorological Agency(JMA) tropical cyclone tracks and intensive surface observations are used to diagnose the features of moisture transport of tropical storm Bilis(No. 0604), which is simulated by the WRF(weather research and forecasting) mesoscale numerical model. It is shown that the Bilis was linked with the moisture channel in the lower latitudes after its landing. Meanwhile, the cross-equatorial flows over 80°-100°E and Somali were active and brought abundant water vapor into the tropical storm, facilitating the maintenance of the landing storm with intensified heavy rainfall along its path. The simulation suggested that the decreased water vapor from lower latitudes prevents the maintenance of Bilis and the development of rainfall. While the cross-equatorial flows over 80°-100°E and Somali were in favor of keeping the cyclonic circulation over land. If the moisture supply fro m the Somali jet stream was reduced, the strength and area of heavy rainfall in tropical cyclone would be remarkably weakened. Consequently, the decreased water vapor from lower latitudes can remarkably suppress the deep convection in tropical storm, then Bilis was damped without the persistent energy support and the rainfall was diminished accordingly.展开更多
Bilis (0604) is a strong tropical storm that sustained over land for a long time, bringing torrential rain. With conventional observation data, radar data and infrared satellite imagery, Mesoscale Convective Systems (...Bilis (0604) is a strong tropical storm that sustained over land for a long time, bringing torrential rain. With conventional observation data, radar data and infrared satellite imagery, Mesoscale Convective Systems (MCSs) are found to form and develop successively, which cause torrential rain. Then numerical simulation is conducted using MM5 to simulate a 66-h post-landfall process. The simulated distribution and intensity of precipitation match the observation well. With the simulated result, the characteristics and process of MCS development are analyzed with the finding that the convergence of the tropical depression and South China Sea (SCS) summer monsoon over The south of China causes the formation of a mesoscale vortex, mesoscale convergence center and mesoscale convergence line, which are favorable to the development and sustaining of the MCSs. A sensitivity experiment indicates that the SCS summer monsoon transports unstable energy and water vapor continuously, which is of vital importance to rainstorms.展开更多
Hepatobiliary cancers are highly lethal cancers that comprise a spectrum of invasive carcinomas originating in the liver hepatocellular carcinoma,the bile ducts intrahepatic cholangiocarcinoma and extrahepaticcholangi...Hepatobiliary cancers are highly lethal cancers that comprise a spectrum of invasive carcinomas originating in the liver hepatocellular carcinoma,the bile ducts intrahepatic cholangiocarcinoma and extrahepaticcholangiocarcinoma,the gallbladder and the ampulla of Vater(collectively known as biliary tract cancers).These tumors account for approximately 13% of all annual cancer-related deaths worldwide and for 10%-20% of deaths from hepatobiliary malignancies.Cholangiocarcinoma(CCA) is a devastating disease that displays a poor survival rate for which few therapeutic options are available.Population genetics,geographical and environmental factors,cholelithiasis,obesity,parity,and endemic infection with liver flukes have been identified as risk factors that influence the development of biliary tract tumors.Other important factors affecting the carcinogenesis of these tumors include chronic inflammation,obstruction of the bile ducts,and impaired bile flow.It has been suggested that CCA is caused by infection with Helicobacter species,such as Helicobacter bilis and Helicobacter hepaticus,in a manner that is similar to the reported role of Helicobacter pylori in distal gastric cancer.Due to the difficulty in culturing these Helicobacter species,molecular methods,such as polymerase chain reaction and sequencing,or immunologic assays have become the methods of choice for diagnosis.However,clinical studies of benign or malignant biliary tract diseases revealed remarkable variability in the methods and the findings,and the use of uniform and validated techniques is needed.展开更多
Preoperative biliary drainage(PBD) was developed to improve obstructive jaundice, which affects a number of organs and physiological mechanisms in patients waiting for surgery. However, its role in patients who will u...Preoperative biliary drainage(PBD) was developed to improve obstructive jaundice, which affects a number of organs and physiological mechanisms in patients waiting for surgery. However, its role in patients who will undergo pancreaticoduodenectomy for biliary obstruction remains controversial. This article aims to review the current status of the use of preoperative drainage for distal biliary obstruction. Relevant articles published from 1980 to 2015 were identified by searching MEDLINE and Pub Med using the keywords "PBD", "pancreaticoduodenectomy", and "obstructive jaundice". Additional papers were identified by a manual search of the references from key articles. Current studies have demonstrated that PBD should not be routinely performed because of the postoperative complications. PBD should only be considered in carefully selected patients, particularly in cases where surgery had to be delayed. PBD may be needed in patients with severe jaundice, concomitant cholangitis, or severe malnutrition. The optimal method of biliary drainage has yet to be confirmed. PBD should be performed by endoscopic routes rather than by percutaneous routes to avoid metastatic tumor seeding. Endoscopic stenting or nasobiliary drainage can be selected. Although more expensive, the use of metallic stents remains a viable option to achieve effective drainage without cholangitis and reintervention.展开更多
We diagnose characteristics of the quasi-balanced flow and secondary circulation（SC） of tropical storm Bilis（2006） using the potential vorticity（PV）-ω inversion method.We further analyze how secondary steering ...We diagnose characteristics of the quasi-balanced flow and secondary circulation（SC） of tropical storm Bilis（2006） using the potential vorticity（PV）-ω inversion method.We further analyze how secondary steering flows associated with mesoscale convective systems affected the track of tropical storm Bilis after it made landfall.The quasi-balanced asymmetric and axisymmetric circulation structures of tropical storm Bilis are represented well by the PV-w inversion.The magnitude of the nonlinear quasi-balanced vertical velocity is approximately 75%of the magnitude simulated using the Weather Research and Forecasting（WRF） model.The SC of Bilis（2006） contained two strong regions of ascending motion,both of which were located in the southwest quadrant of the storm.The first（150-200 km southwest of the storm center） corresponded to the eyewall region,while the second（approximately 400 km southwest of the storm center） corresponded to latent heat release associated with strong precipitation in major spiral rainbands.The SC was very weak in the northeast quadrant（the upshear direction）.Dynamical processes related to the environmental vertical wind shear produced an SC that partially offset the destructive effects of the environmental vertical wind shear（by 20%-25%）.This SC consisted of upward motion in the southwest quadrant and subsidence in the northeast quadrant,with airflow oriented from southwest to northeast at high altitudes and from northeast to southwest at lower levels.The inverted secondary zonal and meridional steering flows associated with continuous asymmetric mesoscale convective systems were about-2.14 and-0.7 m s^（-1）,respectively.These steering flows contributed substantially to the zonal（66.15%） and meridional（33.98%） motion of the storm at 0000 UTC15 July 2006.The secondary steering flow had a significant influence on changing the track of Bilis from southward to northward.The direction of the large-scale meridional steering flow（3.02 m s^（-1）） was opposite to the actual meridional motion（-2.06 m s^（-1））.展开更多
文摘采用水平分辨率1°×1°的NCEP再分析资料、1°×1°的NCEP GDAS资料和2.5°×2.5°的NOAA大气环流资料,结合NOAA HYSPLIT v4.8轨迹模式对0604号热带风暴"Bilis"整个生命史的水汽输送特征进行模拟分析,并分析了"Bilis"暴雨增幅前和增幅后的水汽输送轨迹及不同来源的水汽贡献。结果表明,"Bilis"整个活动过程中主要有四支水汽输送通道,分别是源自索马里、孟加拉湾、120°E越赤道气流和东太平洋的水汽,其中源自索马里和孟加拉湾的西南水汽输送(偏南水汽通道)占主导地位,120°E越赤道气流和东太平洋的水汽是西南水汽随着"Bilis"环流逆时针旋转,自环流中心东北侧进入雨区(东北水汽通道),是低压环流与偏南风相互作用的结果。其中,偏南通道水汽大部分输送到850 h Pa以下的低层,自环流北侧输入的水汽则主要输送到暴雨区上空850 h Pa以上。对比暴雨增幅前后各通道的水汽贡献率发现,孟加拉湾西南气流输送的低纬水汽对此次暴雨增幅的形成、发展起重要作用。
基金National Basic Research Program of China (973 Program, 2009CB421505)National Key Technology R&D Program (2007BAC29B02)Qing Lan Project of Jiangsu Province
文摘By using the dataset of CMA-STI Tropical Cyclone Optimal Tracks, NCEP/NCAR reanalysis and intensive surface observations, a study is performed of the influences of a low-latitude monsoon surge on the longer persistence and increase in torrential rains from the landing tropical storm Bilis. Results suggest that the southwest monsoon was anomalously active after Bilis came ashore. The westerly winds in Bilis's south side might give rise to the poleward movement of the SW monsoon, thus enlarging the pressure gradient between Bilis and the anticyclonic circulation to the south with the result of greatly intensified SW monsoon, which fueled plentiful water vapor, heat and momentum into the declining Bilis and allowed its long stay over land instead of erosion and disappearance. Before Bilis's landfall, the 2006 East Asian monsoon surge, characterized by the atmospheric ISO, experienced remarkable northward propagation. After landfall, the strong surge and powerful low frequency vapor convergence were just on the south side of Bilis, resulting in sharply increased rainfall. In addition, a broad belt of high-valued vapor fluxes extended from the eastern Arabian Sea via the Bay of Bengal, Indochina Peninsula and the South China Sea into the south of China. The belt was linked with the SW monsoon surge forming a moist tongue stretching from the Bay of Bengal to the south of China, which supplied continuously abundant vapor for Bilis along with the surge propagating poleward.
基金Major Program of the Natural Science Researches for Colleges and Universities in Jiangsu Province(14KJA170004)'333'Project of Jiangsu ProvinceNational Natural Science Foundation of China(41575081,41175061)
文摘The NCEP/NCAR reanalysis, Japan Meteorological Agency(JMA) tropical cyclone tracks and intensive surface observations are used to diagnose the features of moisture transport of tropical storm Bilis(No. 0604), which is simulated by the WRF(weather research and forecasting) mesoscale numerical model. It is shown that the Bilis was linked with the moisture channel in the lower latitudes after its landing. Meanwhile, the cross-equatorial flows over 80°-100°E and Somali were active and brought abundant water vapor into the tropical storm, facilitating the maintenance of the landing storm with intensified heavy rainfall along its path. The simulation suggested that the decreased water vapor from lower latitudes prevents the maintenance of Bilis and the development of rainfall. While the cross-equatorial flows over 80°-100°E and Somali were in favor of keeping the cyclonic circulation over land. If the moisture supply fro m the Somali jet stream was reduced, the strength and area of heavy rainfall in tropical cyclone would be remarkably weakened. Consequently, the decreased water vapor from lower latitudes can remarkably suppress the deep convection in tropical storm, then Bilis was damped without the persistent energy support and the rainfall was diminished accordingly.
基金Experiement on the coupling of typhoons, waves and storm surges in the South China Sea and estimation of typhoon-inflicted disasters,a project from the Research Foundation for Tropical and Marine Meteorological Sciencea project from the Natural Science Foundation of China (40333026)
文摘Bilis (0604) is a strong tropical storm that sustained over land for a long time, bringing torrential rain. With conventional observation data, radar data and infrared satellite imagery, Mesoscale Convective Systems (MCSs) are found to form and develop successively, which cause torrential rain. Then numerical simulation is conducted using MM5 to simulate a 66-h post-landfall process. The simulated distribution and intensity of precipitation match the observation well. With the simulated result, the characteristics and process of MCS development are analyzed with the finding that the convergence of the tropical depression and South China Sea (SCS) summer monsoon over The south of China causes the formation of a mesoscale vortex, mesoscale convergence center and mesoscale convergence line, which are favorable to the development and sustaining of the MCSs. A sensitivity experiment indicates that the SCS summer monsoon transports unstable energy and water vapor continuously, which is of vital importance to rainstorms.
文摘Hepatobiliary cancers are highly lethal cancers that comprise a spectrum of invasive carcinomas originating in the liver hepatocellular carcinoma,the bile ducts intrahepatic cholangiocarcinoma and extrahepaticcholangiocarcinoma,the gallbladder and the ampulla of Vater(collectively known as biliary tract cancers).These tumors account for approximately 13% of all annual cancer-related deaths worldwide and for 10%-20% of deaths from hepatobiliary malignancies.Cholangiocarcinoma(CCA) is a devastating disease that displays a poor survival rate for which few therapeutic options are available.Population genetics,geographical and environmental factors,cholelithiasis,obesity,parity,and endemic infection with liver flukes have been identified as risk factors that influence the development of biliary tract tumors.Other important factors affecting the carcinogenesis of these tumors include chronic inflammation,obstruction of the bile ducts,and impaired bile flow.It has been suggested that CCA is caused by infection with Helicobacter species,such as Helicobacter bilis and Helicobacter hepaticus,in a manner that is similar to the reported role of Helicobacter pylori in distal gastric cancer.Due to the difficulty in culturing these Helicobacter species,molecular methods,such as polymerase chain reaction and sequencing,or immunologic assays have become the methods of choice for diagnosis.However,clinical studies of benign or malignant biliary tract diseases revealed remarkable variability in the methods and the findings,and the use of uniform and validated techniques is needed.
文摘Preoperative biliary drainage(PBD) was developed to improve obstructive jaundice, which affects a number of organs and physiological mechanisms in patients waiting for surgery. However, its role in patients who will undergo pancreaticoduodenectomy for biliary obstruction remains controversial. This article aims to review the current status of the use of preoperative drainage for distal biliary obstruction. Relevant articles published from 1980 to 2015 were identified by searching MEDLINE and Pub Med using the keywords "PBD", "pancreaticoduodenectomy", and "obstructive jaundice". Additional papers were identified by a manual search of the references from key articles. Current studies have demonstrated that PBD should not be routinely performed because of the postoperative complications. PBD should only be considered in carefully selected patients, particularly in cases where surgery had to be delayed. PBD may be needed in patients with severe jaundice, concomitant cholangitis, or severe malnutrition. The optimal method of biliary drainage has yet to be confirmed. PBD should be performed by endoscopic routes rather than by percutaneous routes to avoid metastatic tumor seeding. Endoscopic stenting or nasobiliary drainage can be selected. Although more expensive, the use of metallic stents remains a viable option to achieve effective drainage without cholangitis and reintervention.
基金Supported by the National(Key)Basic Research and Development(973)Program of China(2009CB421503)International Cooperating Program of Science and Technology(2010DFA24650)+1 种基金National Natural Science Foundation of China(41375098 and 41175061)the Priority Academic Program Development of Jiangsu Higher Education Institutions(PAPD)
文摘We diagnose characteristics of the quasi-balanced flow and secondary circulation（SC） of tropical storm Bilis（2006） using the potential vorticity（PV）-ω inversion method.We further analyze how secondary steering flows associated with mesoscale convective systems affected the track of tropical storm Bilis after it made landfall.The quasi-balanced asymmetric and axisymmetric circulation structures of tropical storm Bilis are represented well by the PV-w inversion.The magnitude of the nonlinear quasi-balanced vertical velocity is approximately 75%of the magnitude simulated using the Weather Research and Forecasting（WRF） model.The SC of Bilis（2006） contained two strong regions of ascending motion,both of which were located in the southwest quadrant of the storm.The first（150-200 km southwest of the storm center） corresponded to the eyewall region,while the second（approximately 400 km southwest of the storm center） corresponded to latent heat release associated with strong precipitation in major spiral rainbands.The SC was very weak in the northeast quadrant（the upshear direction）.Dynamical processes related to the environmental vertical wind shear produced an SC that partially offset the destructive effects of the environmental vertical wind shear（by 20%-25%）.This SC consisted of upward motion in the southwest quadrant and subsidence in the northeast quadrant,with airflow oriented from southwest to northeast at high altitudes and from northeast to southwest at lower levels.The inverted secondary zonal and meridional steering flows associated with continuous asymmetric mesoscale convective systems were about-2.14 and-0.7 m s^（-1）,respectively.These steering flows contributed substantially to the zonal（66.15%） and meridional（33.98%） motion of the storm at 0000 UTC15 July 2006.The secondary steering flow had a significant influence on changing the track of Bilis from southward to northward.The direction of the large-scale meridional steering flow（3.02 m s^（-1）） was opposite to the actual meridional motion（-2.06 m s^（-1））.
