目的探讨双能量虚拟去钙成像(VNCa)CT对中轴性脊柱关节炎相关骶髂关节炎病人骨髓水肿的诊断价值。材料与方法这项前瞻性研究连续收集2016年4月—2017年12月期间47例受试者[年龄14~41岁,平均27岁(男28例,年龄14~37岁,平均24岁;女19例,年...目的探讨双能量虚拟去钙成像(VNCa)CT对中轴性脊柱关节炎相关骶髂关节炎病人骨髓水肿的诊断价值。材料与方法这项前瞻性研究连续收集2016年4月—2017年12月期间47例受试者[年龄14~41岁,平均27岁(男28例,年龄14~37岁,平均24岁;女19例,年龄17~41岁,平均29岁)],行双能CT和3.0 T MRI检查。展开更多
At present,most total knee replacement(TKR)prostheses on the market are designed according to the sizes of Caucasians.However,extensive studies have indicated that human anatomies differ among different ethnicities.A ...At present,most total knee replacement(TKR)prostheses on the market are designed according to the sizes of Caucasians.However,extensive studies have indicated that human anatomies differ among different ethnicities.A number of reports have indicated that Chinese TKR patients do not match with available prostheses.In this study,computed tomography(CT)images of 52 knees of Chinese men and women were used for anthropometric measurements.Index and geometric measurements were definedand used for correlation analysis.Key parameters from the measurement results were identified.Detailed geometries of knees were measured as coordinates.A deformable three-dimensional(3D)knee modelbased on anatomical coordinates correlating with the identified key parameters was generated.A pros-thesis was then designed according to the analyzed results.Surface matching analysis,bone resectionanalysis,and cadaveric trials were conducted and compared with commercial products to validate theproposed design.The femoral component designed by this study resulted in the highest accuracy(rootmean square point-to-surface(RMS PS),(1.08±0.20)mm)and lowest amount of resected bone volume(27412mm^(3))in comparison with two commercial knee prostheses.This study suggests a new approachfor population-based patient-specific femoral prosthesis design With a single,easilty acquired dimen-sion-namely,epicondyle width(ECW)-as input,a patient-specific femoral prosthesis can be designed according to the analyzed measured data and manufactured by additive manufacturing(AM)methods.Meanwhile,the reconstructed femoral condylar surface was compared with the femoral condylar surfacein the original CT scanning data The average RMS PS distance of the reconstructed femoral condylar surface among all data was(1.10±0.18)mm,which is comparable to other statistical shape modeling methods using multiple radiographs as input data.There is a need to develop an anthropometric-based knee prosthesis for the Chinese population.Based on the anthropometry of the Chinese population,our new design fits Chinese patients better and reserves more bone volume compared with current commercial prostheses,which is an essential step toward AM for personalized knee prostheses.展开更多
The Large High Altitude Air Shower Observatory(LHAASO)has three sub-arrays,KM2A,WCDA,and WFCTA.The flux variations of cosmic ray air showers were studied by analyzing the KM2A data during a thunderstorm on June 10,202...The Large High Altitude Air Shower Observatory(LHAASO)has three sub-arrays,KM2A,WCDA,and WFCTA.The flux variations of cosmic ray air showers were studied by analyzing the KM2A data during a thunderstorm on June 10,2021.The number of shower events that meet the trigger conditions increases significantly in atmospheric electric fields,with a maximum fractional increase of 20%.The variations in trigger rates(increases or decreases)were found to be strongly dependent on the primary zenith angle.The flux of secondary particles increased significantly,following a trend similar to that of shower events.To better understand the observed behavior,Monte Carlo simulations were performed with CORSIKA and G4KM2A(a code based on GEANT4).We found that the experimental data(in saturated negative fields)were in good agreement with the simulations,assuming the presence of a uniform electric field of-700 V/cm with a thickness of 1500 m in the atmosphere above the observation level.Due to the acceleration/deceleration by the atmospheric electric field,the number of secondary particles with energy above the detector threshold was modified,resulting in the changes in shower detection rate.展开更多
A finite volume(FV)method for simulating 3D Fluid-Structure Interaction(FSI)is presented in this paper.The fluid flow is simulated using a parallel unstructured multigrid preconditioned implicit compressible solver,wh...A finite volume(FV)method for simulating 3D Fluid-Structure Interaction(FSI)is presented in this paper.The fluid flow is simulated using a parallel unstructured multigrid preconditioned implicit compressible solver,whist a 3D matrix-free implicit unstructured multigrid finite volume solver is employed for the structural dynamics.The two modules are then coupled using a so-called immersed membrane method(IMM).Large-Eddy Simulation(LES)is employed to predict turbulence.Results from several moving boundary and FSI problems are presented to validate proposed methods and demonstrate their efficiency。展开更多
Introduction One of main scientific goals of the Large High Altitude Air Shower Observatory(LHAASO)is to accurately measure the energy spectra of different cosmic ray compositions around the‘knee’region.The Wide Fiel...Introduction One of main scientific goals of the Large High Altitude Air Shower Observatory(LHAASO)is to accurately measure the energy spectra of different cosmic ray compositions around the‘knee’region.The Wide Field-of-View(FoV)Cherenkov Telescope Array(WFCTA),which is one of the main detectors of LHAASO and has 18 telescopes,is built to achieve this goal.Multiple telescopes are put together and point to connected directions for a larger FoV.Method Telescopes are deployed spatially as close as possible,but due to their own size,the distance between two adjacent telescopes is about 10 m.Therefore,the Cherenkov lateral distribution and the parallax between the two telescopes should be considered in the event building process for images crossing over the boundaries of FoVs of the telescopes.An event building method for Cherenkov images measured by multiple telescopes of WFCTA is developed.The performance of the shower measurements using the combined images is evaluated by comparing with showers that are fully contained by a virtual telescope in simulation.Results and conclusion It is proved that the developed event building process can help to increase the FoV of WFCTA by 30%while maintaining the same reconstruction quality,compared to the separate telescope reconstruction method.展开更多
文摘目的探讨双能量虚拟去钙成像(VNCa)CT对中轴性脊柱关节炎相关骶髂关节炎病人骨髓水肿的诊断价值。材料与方法这项前瞻性研究连续收集2016年4月—2017年12月期间47例受试者[年龄14~41岁,平均27岁(男28例,年龄14~37岁,平均24岁;女19例,年龄17~41岁,平均29岁)],行双能CT和3.0 T MRI检查。
文摘At present,most total knee replacement(TKR)prostheses on the market are designed according to the sizes of Caucasians.However,extensive studies have indicated that human anatomies differ among different ethnicities.A number of reports have indicated that Chinese TKR patients do not match with available prostheses.In this study,computed tomography(CT)images of 52 knees of Chinese men and women were used for anthropometric measurements.Index and geometric measurements were definedand used for correlation analysis.Key parameters from the measurement results were identified.Detailed geometries of knees were measured as coordinates.A deformable three-dimensional(3D)knee modelbased on anatomical coordinates correlating with the identified key parameters was generated.A pros-thesis was then designed according to the analyzed results.Surface matching analysis,bone resectionanalysis,and cadaveric trials were conducted and compared with commercial products to validate theproposed design.The femoral component designed by this study resulted in the highest accuracy(rootmean square point-to-surface(RMS PS),(1.08±0.20)mm)and lowest amount of resected bone volume(27412mm^(3))in comparison with two commercial knee prostheses.This study suggests a new approachfor population-based patient-specific femoral prosthesis design With a single,easilty acquired dimen-sion-namely,epicondyle width(ECW)-as input,a patient-specific femoral prosthesis can be designed according to the analyzed measured data and manufactured by additive manufacturing(AM)methods.Meanwhile,the reconstructed femoral condylar surface was compared with the femoral condylar surfacein the original CT scanning data The average RMS PS distance of the reconstructed femoral condylar surface among all data was(1.10±0.18)mm,which is comparable to other statistical shape modeling methods using multiple radiographs as input data.There is a need to develop an anthropometric-based knee prosthesis for the Chinese population.Based on the anthropometry of the Chinese population,our new design fits Chinese patients better and reserves more bone volume compared with current commercial prostheses,which is an essential step toward AM for personalized knee prostheses.
基金Supported in China by National Key R&D program of China(2018YFA0404201,2018YFA0404202,2018YFA0404203,2018YFA0404204)NSFC(U2031101,11475141,12147208)in Thailand by RTA6280002 from Thailand Science Research and Innovation。
文摘The Large High Altitude Air Shower Observatory(LHAASO)has three sub-arrays,KM2A,WCDA,and WFCTA.The flux variations of cosmic ray air showers were studied by analyzing the KM2A data during a thunderstorm on June 10,2021.The number of shower events that meet the trigger conditions increases significantly in atmospheric electric fields,with a maximum fractional increase of 20%.The variations in trigger rates(increases or decreases)were found to be strongly dependent on the primary zenith angle.The flux of secondary particles increased significantly,following a trend similar to that of shower events.To better understand the observed behavior,Monte Carlo simulations were performed with CORSIKA and G4KM2A(a code based on GEANT4).We found that the experimental data(in saturated negative fields)were in good agreement with the simulations,assuming the presence of a uniform electric field of-700 V/cm with a thickness of 1500 m in the atmosphere above the observation level.Due to the acceleration/deceleration by the atmospheric electric field,the number of secondary particles with energy above the detector threshold was modified,resulting in the changes in shower detection rate.
文摘A finite volume(FV)method for simulating 3D Fluid-Structure Interaction(FSI)is presented in this paper.The fluid flow is simulated using a parallel unstructured multigrid preconditioned implicit compressible solver,whist a 3D matrix-free implicit unstructured multigrid finite volume solver is employed for the structural dynamics.The two modules are then coupled using a so-called immersed membrane method(IMM).Large-Eddy Simulation(LES)is employed to predict turbulence.Results from several moving boundary and FSI problems are presented to validate proposed methods and demonstrate their efficiency。
基金supported by the National Key R&D program of China under grants 2018YFA0404201This research work is also supported by the National Natural Science Foundation of China,with NSFC Grants No.11635011,No.11761141001,No.11905240,No.12105293,No.12105294,No.U2031103,No.U1831208,No.11503021,No.11205126,No.11947404,and No.11675187+2 种基金by IHEP innovation project No.E25451U2by the Science and Technology Department of Sichuan Province 2021YFSY0031by the Xiejialin Foundation of IHEP No.E2546IU2,by RTA6280002 from Thailand Science Research and Innovation in Thailand.
文摘Introduction One of main scientific goals of the Large High Altitude Air Shower Observatory(LHAASO)is to accurately measure the energy spectra of different cosmic ray compositions around the‘knee’region.The Wide Field-of-View(FoV)Cherenkov Telescope Array(WFCTA),which is one of the main detectors of LHAASO and has 18 telescopes,is built to achieve this goal.Multiple telescopes are put together and point to connected directions for a larger FoV.Method Telescopes are deployed spatially as close as possible,but due to their own size,the distance between two adjacent telescopes is about 10 m.Therefore,the Cherenkov lateral distribution and the parallax between the two telescopes should be considered in the event building process for images crossing over the boundaries of FoVs of the telescopes.An event building method for Cherenkov images measured by multiple telescopes of WFCTA is developed.The performance of the shower measurements using the combined images is evaluated by comparing with showers that are fully contained by a virtual telescope in simulation.Results and conclusion It is proved that the developed event building process can help to increase the FoV of WFCTA by 30%while maintaining the same reconstruction quality,compared to the separate telescope reconstruction method.