In this paper,we consider the limiting spectral distribution of the information-plus-noise type sample covariance matrices Cn=1/N(Rn+σXn)(Rn+σXn),under the assumption that the entries of Xn are independent but...In this paper,we consider the limiting spectral distribution of the information-plus-noise type sample covariance matrices Cn=1/N(Rn+σXn)(Rn+σXn),under the assumption that the entries of Xn are independent but non-identically distributed random variables.It is proved that,almost surely,the empirical spectral distribution of Cn converges weakly to a non-random distribution whose Stieltjes transform satisfies a certain equation.Our result extends the previous one with the entries of Xn are i.i.d.random varibles to a more general case.The proof of the result mainly employs the Stein equation and the cumulant expansion formula of independent random variables.展开更多
For high reliability and long life systems, system pass/fail data are often rare. Integrating lower-level data, such as data drawn from the subsystem or component pass/fail testing,the Bayesian analysis can improve th...For high reliability and long life systems, system pass/fail data are often rare. Integrating lower-level data, such as data drawn from the subsystem or component pass/fail testing,the Bayesian analysis can improve the precision of the system reliability assessment. If the multi-level pass/fail data are overlapping,one challenging problem for the Bayesian analysis is to develop a likelihood function. Since the computation burden of the existing methods makes them infeasible for multi-component systems, this paper proposes an improved Bayesian approach for the system reliability assessment in light of overlapping data. This approach includes three steps: fristly searching for feasible paths based on the binary decision diagram, then screening feasible points based on space partition and constraint decomposition, and finally simplifying the likelihood function. An example of a satellite rolling control system demonstrates the feasibility and the efficiency of the proposed approach.展开更多
Under special conditions on data set and underlying distribution, the limit of finite sample breakdown point of Tukey's halfspace median (1) has been obtained in the literature. In this paper, we establish the resu...Under special conditions on data set and underlying distribution, the limit of finite sample breakdown point of Tukey's halfspace median (1) has been obtained in the literature. In this paper, we establish the result under weaker assumptions imposed on underlying distribution (weak smoothness) and on data set (not necessary in general position). The refined representation of Tukey's sample depth regions for data set not necessary in general position is also obtained, as a by-product of our derivation.展开更多
Background Mycophenolic acid (MPA) as an anti-proliferative immune-suppressive agent is used in the majority of immunosuppressive regimens in solid organ transplantation. This study aimed to investigate the pharmaco...Background Mycophenolic acid (MPA) as an anti-proliferative immune-suppressive agent is used in the majority of immunosuppressive regimens in solid organ transplantation. This study aimed to investigate the pharmacokinetic (PK) characteristics of enteric-coated mycophenolate sodium (EC-MPS) and area under the curve (AUC) from 0 to 12 hours with limited sampling strategies (LSSs) in Chinese renal transplant recipients. Methods This study was conducted in 10 Chinese renal transplant patients receiving living donor and treated with EC-MPS, cyclosporine, and corticosteroids. MPA concentrations were measured by enzyme multiplied immunoassay technique (EMIT). Whole 12-hour PK profiles were obtained on Day 4 after operation. LSSs with jackknife technique, multiple stepwise regression analysis, and Bland-Altman analysis were developed to estimate MPAAUC. Results The mean maximum plasma concentration, the mean time for it to reach peak (Tmax), and the mean MPA AUC were (11.38±2.49) mg/L, (4.85±3.32) hours, and (63.19±13.54) mg.h.L1, respectively. Among the 10 profiles, MPA AUC of four patients was significantly higher than that of the other six patients, and the corresponding Tmax was significantly longer than that of the other six patients. No patient exhibited a second peak caused by enterohepatic recirculation. The best models were as follows: 27.46+0.94C3+3.24C8+2.81C10 (f2=0.972), which was used to predict AUC of fast metabolizer with a mean prediction error (MPE) of -0.21% and a mean absolute prediction error (MAE) of 2.59%; 36.65+3.08Ce+5.30C10-4.04C12 (r2=0.992), which was used to predict AUC of slow metabolizer with a MPE of 0.58% and a MAE of 1.95%. Conclusions The PKs of EC-MPS had a high variability among Chinese renal transplant recipients. The preliminary PK data indicated the existence of slow and fast metabolizer. These findings may be associated with the enterohepatic rec.irculation.展开更多
基金supported by the National Natural Science Foundation of China(11071213,11101362)Natural Science Foundation of Zhejiang Province(R6090034)Specialized Research Foundation for the Doctor Program of Higher Education(20100101110001)
文摘In this paper,we consider the limiting spectral distribution of the information-plus-noise type sample covariance matrices Cn=1/N(Rn+σXn)(Rn+σXn),under the assumption that the entries of Xn are independent but non-identically distributed random variables.It is proved that,almost surely,the empirical spectral distribution of Cn converges weakly to a non-random distribution whose Stieltjes transform satisfies a certain equation.Our result extends the previous one with the entries of Xn are i.i.d.random varibles to a more general case.The proof of the result mainly employs the Stein equation and the cumulant expansion formula of independent random variables.
基金supported by the National Natural Science Foundation of China(61304218)
文摘For high reliability and long life systems, system pass/fail data are often rare. Integrating lower-level data, such as data drawn from the subsystem or component pass/fail testing,the Bayesian analysis can improve the precision of the system reliability assessment. If the multi-level pass/fail data are overlapping,one challenging problem for the Bayesian analysis is to develop a likelihood function. Since the computation burden of the existing methods makes them infeasible for multi-component systems, this paper proposes an improved Bayesian approach for the system reliability assessment in light of overlapping data. This approach includes three steps: fristly searching for feasible paths based on the binary decision diagram, then screening feasible points based on space partition and constraint decomposition, and finally simplifying the likelihood function. An example of a satellite rolling control system demonstrates the feasibility and the efficiency of the proposed approach.
基金Supported by NSF of China(Grant Nos.11601197,11461029 and 61563018)Ministry of Education Humanity Social Science Research Project of China(Grant No.15JYC910002)+2 种基金China Postdoctoral Science Foundation Funded Project(Grant Nos.2016M600511 and 2017T100475)NSF of Jiangxi Province(Grant Nos.20171ACB21030,20161BAB201024 and 20161ACB20009)the Key Science Fund Project of Jiangxi Provincial Education Department(Grant Nos.GJJ150439,KJLD13033 and KJLD14034)
文摘Under special conditions on data set and underlying distribution, the limit of finite sample breakdown point of Tukey's halfspace median (1) has been obtained in the literature. In this paper, we establish the result under weaker assumptions imposed on underlying distribution (weak smoothness) and on data set (not necessary in general position). The refined representation of Tukey's sample depth regions for data set not necessary in general position is also obtained, as a by-product of our derivation.
文摘Background Mycophenolic acid (MPA) as an anti-proliferative immune-suppressive agent is used in the majority of immunosuppressive regimens in solid organ transplantation. This study aimed to investigate the pharmacokinetic (PK) characteristics of enteric-coated mycophenolate sodium (EC-MPS) and area under the curve (AUC) from 0 to 12 hours with limited sampling strategies (LSSs) in Chinese renal transplant recipients. Methods This study was conducted in 10 Chinese renal transplant patients receiving living donor and treated with EC-MPS, cyclosporine, and corticosteroids. MPA concentrations were measured by enzyme multiplied immunoassay technique (EMIT). Whole 12-hour PK profiles were obtained on Day 4 after operation. LSSs with jackknife technique, multiple stepwise regression analysis, and Bland-Altman analysis were developed to estimate MPAAUC. Results The mean maximum plasma concentration, the mean time for it to reach peak (Tmax), and the mean MPA AUC were (11.38±2.49) mg/L, (4.85±3.32) hours, and (63.19±13.54) mg.h.L1, respectively. Among the 10 profiles, MPA AUC of four patients was significantly higher than that of the other six patients, and the corresponding Tmax was significantly longer than that of the other six patients. No patient exhibited a second peak caused by enterohepatic recirculation. The best models were as follows: 27.46+0.94C3+3.24C8+2.81C10 (f2=0.972), which was used to predict AUC of fast metabolizer with a mean prediction error (MPE) of -0.21% and a mean absolute prediction error (MAE) of 2.59%; 36.65+3.08Ce+5.30C10-4.04C12 (r2=0.992), which was used to predict AUC of slow metabolizer with a MPE of 0.58% and a MAE of 1.95%. Conclusions The PKs of EC-MPS had a high variability among Chinese renal transplant recipients. The preliminary PK data indicated the existence of slow and fast metabolizer. These findings may be associated with the enterohepatic rec.irculation.