If an explicit time scheme is used in a numerical model, the size of the integration time step is typically limited by the spatial resolution. This study develops a regular latitude–longitude grid-based global three-...If an explicit time scheme is used in a numerical model, the size of the integration time step is typically limited by the spatial resolution. This study develops a regular latitude–longitude grid-based global three-dimensional tracer transport model that is computationally stable at large time-step sizes. The tracer model employs a finite-volume flux-form semiLagrangian transport scheme in the horizontal and an adaptively implicit algorithm in the vertical. The horizontal and vertical solvers are coupled via a straightforward operator-splitting technique. Both the finite-volume scheme's onedimensional slope-limiter and the adaptively implicit vertical solver's first-order upwind scheme enforce monotonicity. The tracer model permits a large time-step size and is inherently conservative and monotonic. Idealized advection test cases demonstrate that the three-dimensional transport model performs very well in terms of accuracy, stability, and efficiency. It is possible to use this robust transport model in a global atmospheric dynamical core.展开更多
BACKGROUND Traditional methods cannot clearly visualize esophageal cancer(EC)tumor contours and metastases,which limits the clinical application of da Vinci robotassisted surgery.AIM To investigate the efficacy of the...BACKGROUND Traditional methods cannot clearly visualize esophageal cancer(EC)tumor contours and metastases,which limits the clinical application of da Vinci robotassisted surgery.AIM To investigate the efficacy of the da Vinci robot in combination with nanocarbon lymph node tracers in radical surgery of EC.METHODS In total,104 patients with early-stage EC who were admitted to Liuzhou worker's Hospital from January 2020 to June 2023 were enrolled.The patients were assigned to an observation group(n=52),which underwent da Vinci robot-assisted minimally invasive esophagectomy(RAMIE)with the intraoperative use of nanocarbon tracers,and a control group(n=52),which underwent traditional surgery treatment.The operation time,intraoperative blood loss,postoperative drainage tube indwelling time,hospital stay,number of lymph nodes dissected,incidence of complications,and long-term curative effects were comparatively analyzed.The postoperative stress response C-reactive protein(CRP),cortisol,epinephrine(E)and inflammatory response interleukin(IL)-6,IL-8,IL-10,and tumor necrosis factor-alpha(TNF-α)were evaluated.RESULTS Compared with the control group,the observation group had significantly lower postoperative CRP,cortisol,and E levels(P<0.05)with a milder inflammatory response,as indicated by lower IL-6,IL-10,and TNF-αlevels(P<0.05).Patients who underwent RAMIE had less intraoperative blood loss and shorter operation times and hospital stays than those who underwent traditional surgery.The average number of dissected lymph nodes,time of lymph node dissection,and mean smallest lymph node diameter were all significantly lower in the observation group(P<0.05).The rate of postoperative complications was 5.77%in the observation group,significantly lower than the 15.38%observed in the control group.Furthermore,the lymphatic metastasis rate,reoperation rate,and 12-and 24-month cumulative mortality in the observation group were 1.92%,0%,0%,and 0%,respectively,all of which were significantly lower than those in the control group(P<0.05).CONCLUSION The treatment of EC using the da Vinci robot combined with nanocarbon lymph node tracers can achieve good surgical outcomes and demonstrates promising clinical applications.展开更多
Nitrogen fixation is one of the most important sources of new nitrogen in the ocean and thus profoundly affects the nitrogen and carbon biogeochemical processes.The distribution,controlling factors,and flux of N2 fixa...Nitrogen fixation is one of the most important sources of new nitrogen in the ocean and thus profoundly affects the nitrogen and carbon biogeochemical processes.The distribution,controlling factors,and flux of N2 fixation in the global ocean remain uncertain,partly because of the lack of methodological uniformity.The^(15)N_(2)tracer assay(the original bubble method→the^(15)N_(2)-enriched seawater method→the modified bubble method)is the mainstream method for field measurements of N2 fixation rates(NFRs),among which the original bubble method is the most frequently used.However,accumulating evidence has suggested an underestimation of NFRs when using this method.To improve the availability of previous data,we compared NFRs measured by three^(15)N_(2)tracer assays in the South China Sea.Our results indicate that the relationship between NFRs measured by the original bubble method and the^(15)N_(2)-enriched seawater method varies obviously with area and season,which may be influenced by incubation time,diazotrophic composition,and environmental factors.In comparison,the relationship between NFRs measured by the original bubble method and the modified bubble method is more stable,indicating that the N2 fixation rates based on the original bubble methods may be underestimated by approximately 50%.Based on this result,we revised the flux of N2 fixation in the South China Sea to 40 mmol/(m2·a).Our results improve the availability and comparability of literature NFR data in the South China Sea.The comparison of the^(15)N_(2)tracer assay for NFRs measurements on a larger scale is urgently necessary over the global ocean for a more robust understanding of the role of N2 fixation in the marine nitrogen cycle.展开更多
The tracer technique is recommended as an effective tool in surveying abnormal seepage through lakes and dams. By injecting a tracer into a known upstream location and monitoring the appearance of the tracer in the do...The tracer technique is recommended as an effective tool in surveying abnormal seepage through lakes and dams. By injecting a tracer into a known upstream location and monitoring the appearance of the tracer in the downstream leak point, it is possible to determine the direction and the average water velocity of the preferential flow through the dam. The detailed result achieved depends on the number of samples and the sampling locations to analyze tracer concentration over time in the field. This study proposes to use noninvasive self-potential measurements to determine the location and time the salt tracer moves through the seepage zone. The connection between the potential signal according to the propagation of the NaCl salt tracer and the water velocity was demonstrated through an experiment on a sandbox model. Experimental results express a good agreement between the time to reach the maximum value of the potential variation and the salt concentration variation with the time that water comes to monitoring locations. The result indicates an ability to determine the pore water velocity of the seepage zone based on the recording of potential signals produced by a salt tracer movement. The salt tracer test using NaCl combined with self-potential measurements was then applied to survey a leaking earth dam in the Dong Nai river basin (Vietnam).展开更多
基金jointly supported by the National Natural Science Foundation of China (Grant No.42075153)the Young Scientists Fund of the Earth System Modeling and Prediction Centre (Grant No. CEMC-QNJJ-2022014)。
文摘If an explicit time scheme is used in a numerical model, the size of the integration time step is typically limited by the spatial resolution. This study develops a regular latitude–longitude grid-based global three-dimensional tracer transport model that is computationally stable at large time-step sizes. The tracer model employs a finite-volume flux-form semiLagrangian transport scheme in the horizontal and an adaptively implicit algorithm in the vertical. The horizontal and vertical solvers are coupled via a straightforward operator-splitting technique. Both the finite-volume scheme's onedimensional slope-limiter and the adaptively implicit vertical solver's first-order upwind scheme enforce monotonicity. The tracer model permits a large time-step size and is inherently conservative and monotonic. Idealized advection test cases demonstrate that the three-dimensional transport model performs very well in terms of accuracy, stability, and efficiency. It is possible to use this robust transport model in a global atmospheric dynamical core.
基金Supported by Guangxi Health Department Scientific Research Program,No.Z20200206Project of Guangxi Liuzhou Science and Technology Bureau,No.2024YB0101B010。
文摘BACKGROUND Traditional methods cannot clearly visualize esophageal cancer(EC)tumor contours and metastases,which limits the clinical application of da Vinci robotassisted surgery.AIM To investigate the efficacy of the da Vinci robot in combination with nanocarbon lymph node tracers in radical surgery of EC.METHODS In total,104 patients with early-stage EC who were admitted to Liuzhou worker's Hospital from January 2020 to June 2023 were enrolled.The patients were assigned to an observation group(n=52),which underwent da Vinci robot-assisted minimally invasive esophagectomy(RAMIE)with the intraoperative use of nanocarbon tracers,and a control group(n=52),which underwent traditional surgery treatment.The operation time,intraoperative blood loss,postoperative drainage tube indwelling time,hospital stay,number of lymph nodes dissected,incidence of complications,and long-term curative effects were comparatively analyzed.The postoperative stress response C-reactive protein(CRP),cortisol,epinephrine(E)and inflammatory response interleukin(IL)-6,IL-8,IL-10,and tumor necrosis factor-alpha(TNF-α)were evaluated.RESULTS Compared with the control group,the observation group had significantly lower postoperative CRP,cortisol,and E levels(P<0.05)with a milder inflammatory response,as indicated by lower IL-6,IL-10,and TNF-αlevels(P<0.05).Patients who underwent RAMIE had less intraoperative blood loss and shorter operation times and hospital stays than those who underwent traditional surgery.The average number of dissected lymph nodes,time of lymph node dissection,and mean smallest lymph node diameter were all significantly lower in the observation group(P<0.05).The rate of postoperative complications was 5.77%in the observation group,significantly lower than the 15.38%observed in the control group.Furthermore,the lymphatic metastasis rate,reoperation rate,and 12-and 24-month cumulative mortality in the observation group were 1.92%,0%,0%,and 0%,respectively,all of which were significantly lower than those in the control group(P<0.05).CONCLUSION The treatment of EC using the da Vinci robot combined with nanocarbon lymph node tracers can achieve good surgical outcomes and demonstrates promising clinical applications.
基金The National Natural Science Foundation of China under contract Nos 42076042 and 41721005the Fund of Ministry of Science and Technology of China under contract No.2017FY201403the Fund of China Ocean Mineral Resources R&D Association under contract No.DY135-13-E2-03.
文摘Nitrogen fixation is one of the most important sources of new nitrogen in the ocean and thus profoundly affects the nitrogen and carbon biogeochemical processes.The distribution,controlling factors,and flux of N2 fixation in the global ocean remain uncertain,partly because of the lack of methodological uniformity.The^(15)N_(2)tracer assay(the original bubble method→the^(15)N_(2)-enriched seawater method→the modified bubble method)is the mainstream method for field measurements of N2 fixation rates(NFRs),among which the original bubble method is the most frequently used.However,accumulating evidence has suggested an underestimation of NFRs when using this method.To improve the availability of previous data,we compared NFRs measured by three^(15)N_(2)tracer assays in the South China Sea.Our results indicate that the relationship between NFRs measured by the original bubble method and the^(15)N_(2)-enriched seawater method varies obviously with area and season,which may be influenced by incubation time,diazotrophic composition,and environmental factors.In comparison,the relationship between NFRs measured by the original bubble method and the modified bubble method is more stable,indicating that the N2 fixation rates based on the original bubble methods may be underestimated by approximately 50%.Based on this result,we revised the flux of N2 fixation in the South China Sea to 40 mmol/(m2·a).Our results improve the availability and comparability of literature NFR data in the South China Sea.The comparison of the^(15)N_(2)tracer assay for NFRs measurements on a larger scale is urgently necessary over the global ocean for a more robust understanding of the role of N2 fixation in the marine nitrogen cycle.
文摘The tracer technique is recommended as an effective tool in surveying abnormal seepage through lakes and dams. By injecting a tracer into a known upstream location and monitoring the appearance of the tracer in the downstream leak point, it is possible to determine the direction and the average water velocity of the preferential flow through the dam. The detailed result achieved depends on the number of samples and the sampling locations to analyze tracer concentration over time in the field. This study proposes to use noninvasive self-potential measurements to determine the location and time the salt tracer moves through the seepage zone. The connection between the potential signal according to the propagation of the NaCl salt tracer and the water velocity was demonstrated through an experiment on a sandbox model. Experimental results express a good agreement between the time to reach the maximum value of the potential variation and the salt concentration variation with the time that water comes to monitoring locations. The result indicates an ability to determine the pore water velocity of the seepage zone based on the recording of potential signals produced by a salt tracer movement. The salt tracer test using NaCl combined with self-potential measurements was then applied to survey a leaking earth dam in the Dong Nai river basin (Vietnam).
