Secret sharing(SS)is part of the essential techniques in cryptography but still faces many challenges in efficiency and security.Currently,SS schemes based on the Chinese Remainder Theorem(CRT)are either low in the in...Secret sharing(SS)is part of the essential techniques in cryptography but still faces many challenges in efficiency and security.Currently,SS schemes based on the Chinese Remainder Theorem(CRT)are either low in the information rate or complicated in construction.To solve the above problems,1)a simple construction of an ideal(t,n)-SS scheme is proposed based on CRT for a polynomial ring.Compared with Ning’s scheme,it is much more efficient in generating n pairwise coprime modular polynomials during the scheme construction phase.Moreover,Shamir’s scheme is also a special case of our scheme.To further improve the security,2)a common-factor-based(t,n)-SS scheme is proposed in which all shareholders share a common polynomial factor.It enables both the verification of received shares and the establishment of a secure channel among shareholders during the reconstruction phase.As a result,the scheme is resistant to eavesdropping and modification attacks by outside adversaries.展开更多
BACKGROUND Previous studies have revealed that patients with asymptomatic common bile duct(CBD)stones are at a high risk of developing post-endoscopic retrograde cholangiopancreatography(ERCP)pancreatitis(PEP).However...BACKGROUND Previous studies have revealed that patients with asymptomatic common bile duct(CBD)stones are at a high risk of developing post-endoscopic retrograde cholangiopancreatography(ERCP)pancreatitis(PEP).However,no studies to date have addressed the risk factors for PEP in patients with asymptomatic CBD stones.AIM To examine the risk factors for PEP in patients with asymptomatic CBD stones.METHODS Using medical records of three institutions in Japan for 6 years,we identified a total of 1135 patients with choledocholithiasis including 967 symptomatic patients and 168 asymptomatic patients with native papilla who underwent therapeutic ERCP.We performed univariate and multivariate analyses to examine the risk factors for PEP in the 168 patients with asymptomatic CBD stones.RESULTS The overall incidence rate of PEP in all the patients with during study period was 4.7%(53/1135).Of the 168 patients with asymptomatic CBD stones,24(14.3%)developed PEP.In univariate analysis,precut sphincterotomy(P=0.009)and biliary balloon sphincter dilation(P=0.043)were significant risk factors for PEP.In multivariate analysis,precut sphincterotomy(P=0.002,95%CI:2.2-27.8,odds ratio=7.7),biliary balloon sphincter dilation(P=0.015,95%CI:1.4-17.3,odds ratio=4.9),and trainee endoscopists(P=0.048,95%CI:1.01-8.1,odds ratio=2.9)were significant risk factors for PEP.CONCLUSION ERCP for asymptomatic CBD stones should be performed by experienced endoscopists.When performing precut sphincterotomy or biliary balloon sphincter dilation in patients with asymptomatic CBD stones,the placement of a prophylactic pancreatic stent is strongly recommended to prevent PEP.展开更多
BACKGROUND Post-endoscopic retrograde cholangiopancreatography(ERCP) pancreatitis(PEP)is a critical and poorly managed complication of ERCP. Endoscopists need to understand the risk factors for PEP. However, the major...BACKGROUND Post-endoscopic retrograde cholangiopancreatography(ERCP) pancreatitis(PEP)is a critical and poorly managed complication of ERCP. Endoscopists need to understand the risk factors for PEP. However, the majority of studies investigating ERCP-related risk factors have included well-trained endoscopists,with the issue of endoscopist experience on PEP incidence not having been systematically evaluated.AIM To explore the risk factors for PEP in beginner endoscopists without supervision.METHODS We performed a retrospective analysis of 293 patients, with na?ve papilla and no history of pancreatitis, treated using bile duct cannulation. Patients were classified according to the endoscopist’s experience(beginner vs expert). The angle of the distal common bile duct(CBD) was measured as the angle between the lower wall of the bile duct and a vertical line extending to the lower wall of the bile duct on coronal view computed tomography.RESULTS After propensity matching, there were no differences between patients treated by the expert and beginner endoscopist with regard to age, sex, mean bile duct dilatation, and ratio of benign disease. The distal CBD angle was classified as acute(> 30o) or obtuse(≤ 30o), based on the mean angle of 29.9o for the group. An acute distal CBD angle was a significant risk factor for PEP for beginner(P =0.049), but not expert.CONCLUSION For beginner endoscopists first performing unsupervised ERCP, cases with an obtuse distal CBD angle may be more appropriate to lower the risk of PEP.展开更多
时间频率传递的结果会受到非模型化误差和观测噪声的影响,其噪声常为高频信号,构建低通滤波器可在一定程度上消除观测值序列中的高频噪声信号.本文对Vondrak滤波函数的本质进行剖析,通过IGG3算法对钟差序列进行定权并采用频率响应法选...时间频率传递的结果会受到非模型化误差和观测噪声的影响,其噪声常为高频信号,构建低通滤波器可在一定程度上消除观测值序列中的高频噪声信号.本文对Vondrak滤波函数的本质进行剖析,通过IGG3算法对钟差序列进行定权并采用频率响应法选择适合的滤波因子;对不同的链路分别进行卫星双向时间频率传递(two-way satellite time and frequency transfer,TWSTFT)、基于软件接收机的卫星双向时间传递(two-way satellite time and frequency transfer based on software defined receiver,SDR-TWSTFT)和短基线共视时间频率传递实验,并对钟差结果采用抗差Vondrak滤波进行平滑去噪.结果表明:滤波后的钟差序列能够很好地反映原始钟差序列的趋势;平滑后的TWSTFT钟差结果,日波动效应得到了有效的抑制,精度有明显提升;对于共视钟差结果,精度有明显提升,与精密单点定位(precise point positioning,PPP)时间传递结果的差值保持在−1.0~1.0 ns范围内.展开更多
基金This work was supported by National Key R&D Project 2018YFB2100300the National Natural Science Foundation of China(Grant No.61520106007).
文摘Secret sharing(SS)is part of the essential techniques in cryptography but still faces many challenges in efficiency and security.Currently,SS schemes based on the Chinese Remainder Theorem(CRT)are either low in the information rate or complicated in construction.To solve the above problems,1)a simple construction of an ideal(t,n)-SS scheme is proposed based on CRT for a polynomial ring.Compared with Ning’s scheme,it is much more efficient in generating n pairwise coprime modular polynomials during the scheme construction phase.Moreover,Shamir’s scheme is also a special case of our scheme.To further improve the security,2)a common-factor-based(t,n)-SS scheme is proposed in which all shareholders share a common polynomial factor.It enables both the verification of received shares and the establishment of a secure channel among shareholders during the reconstruction phase.As a result,the scheme is resistant to eavesdropping and modification attacks by outside adversaries.
文摘BACKGROUND Previous studies have revealed that patients with asymptomatic common bile duct(CBD)stones are at a high risk of developing post-endoscopic retrograde cholangiopancreatography(ERCP)pancreatitis(PEP).However,no studies to date have addressed the risk factors for PEP in patients with asymptomatic CBD stones.AIM To examine the risk factors for PEP in patients with asymptomatic CBD stones.METHODS Using medical records of three institutions in Japan for 6 years,we identified a total of 1135 patients with choledocholithiasis including 967 symptomatic patients and 168 asymptomatic patients with native papilla who underwent therapeutic ERCP.We performed univariate and multivariate analyses to examine the risk factors for PEP in the 168 patients with asymptomatic CBD stones.RESULTS The overall incidence rate of PEP in all the patients with during study period was 4.7%(53/1135).Of the 168 patients with asymptomatic CBD stones,24(14.3%)developed PEP.In univariate analysis,precut sphincterotomy(P=0.009)and biliary balloon sphincter dilation(P=0.043)were significant risk factors for PEP.In multivariate analysis,precut sphincterotomy(P=0.002,95%CI:2.2-27.8,odds ratio=7.7),biliary balloon sphincter dilation(P=0.015,95%CI:1.4-17.3,odds ratio=4.9),and trainee endoscopists(P=0.048,95%CI:1.01-8.1,odds ratio=2.9)were significant risk factors for PEP.CONCLUSION ERCP for asymptomatic CBD stones should be performed by experienced endoscopists.When performing precut sphincterotomy or biliary balloon sphincter dilation in patients with asymptomatic CBD stones,the placement of a prophylactic pancreatic stent is strongly recommended to prevent PEP.
基金Supported by Biomedical Research Institute Grant,No.2019B021,Pusan National University Hospital
文摘BACKGROUND Post-endoscopic retrograde cholangiopancreatography(ERCP) pancreatitis(PEP)is a critical and poorly managed complication of ERCP. Endoscopists need to understand the risk factors for PEP. However, the majority of studies investigating ERCP-related risk factors have included well-trained endoscopists,with the issue of endoscopist experience on PEP incidence not having been systematically evaluated.AIM To explore the risk factors for PEP in beginner endoscopists without supervision.METHODS We performed a retrospective analysis of 293 patients, with na?ve papilla and no history of pancreatitis, treated using bile duct cannulation. Patients were classified according to the endoscopist’s experience(beginner vs expert). The angle of the distal common bile duct(CBD) was measured as the angle between the lower wall of the bile duct and a vertical line extending to the lower wall of the bile duct on coronal view computed tomography.RESULTS After propensity matching, there were no differences between patients treated by the expert and beginner endoscopist with regard to age, sex, mean bile duct dilatation, and ratio of benign disease. The distal CBD angle was classified as acute(> 30o) or obtuse(≤ 30o), based on the mean angle of 29.9o for the group. An acute distal CBD angle was a significant risk factor for PEP for beginner(P =0.049), but not expert.CONCLUSION For beginner endoscopists first performing unsupervised ERCP, cases with an obtuse distal CBD angle may be more appropriate to lower the risk of PEP.
文摘时间频率传递的结果会受到非模型化误差和观测噪声的影响,其噪声常为高频信号,构建低通滤波器可在一定程度上消除观测值序列中的高频噪声信号.本文对Vondrak滤波函数的本质进行剖析,通过IGG3算法对钟差序列进行定权并采用频率响应法选择适合的滤波因子;对不同的链路分别进行卫星双向时间频率传递(two-way satellite time and frequency transfer,TWSTFT)、基于软件接收机的卫星双向时间传递(two-way satellite time and frequency transfer based on software defined receiver,SDR-TWSTFT)和短基线共视时间频率传递实验,并对钟差结果采用抗差Vondrak滤波进行平滑去噪.结果表明:滤波后的钟差序列能够很好地反映原始钟差序列的趋势;平滑后的TWSTFT钟差结果,日波动效应得到了有效的抑制,精度有明显提升;对于共视钟差结果,精度有明显提升,与精密单点定位(precise point positioning,PPP)时间传递结果的差值保持在−1.0~1.0 ns范围内.
