The exact classical limits for the coefficient of variation c for the normal distribution are derived. The hand-calculating approximated classical limits for c having high accuracy are given to meet practical engineer...The exact classical limits for the coefficient of variation c for the normal distribution are derived. The hand-calculating approximated classical limits for c having high accuracy are given to meet practical engineering needs. Using Odeh and Owen's computational method and Brent's algorithm, the tables for the r-upper exact classical limits of coefficient of variation for normal distribution are calculated for the different confidence coefficient y, the sample size n=1(1)30,40,60,120, the sample coefficient of variation c=0.01(0.01)0.20. It is shown that if n<8,c<0.20, then the V -upper exact classical limits cu for c are slightly higher than the exact fiducial limits cu,F for c if. n>8, c<0.02,then cu-cu,f<5x10-6展开更多
AIM:To investigate whether the disease progression of chronic hepatitis C patients with normal alanine aminotransferase(ALT) levels differs by ALT levels.METHODS:A total of 232 chronic hepatitis C patients with normal...AIM:To investigate whether the disease progression of chronic hepatitis C patients with normal alanine aminotransferase(ALT) levels differs by ALT levels.METHODS:A total of 232 chronic hepatitis C patients with normal ALT(< 40 IU/L) were analyzed.The patients were divided into "high-normal" and "low-normal" ALT groups after determining the best predictive cutoff level associated with disease progression for each gender.The incidence of disease progression,as defined by the occurrence of an increase of ≥ 2 points in the Child-Pugh score,spontaneous bacterial peritonitis,bleeding gastric or esophageal varices,hepatic encephalopathy,the development of hepatocellular carcinoma,or death related to liver disease,were compared between the two groups.RESULTS:Baseline serum ALT levels were associatedwith disease progression for both genders.The best predictive cutoff baseline serum ALT level for disease progression was 26 IU/L in males and 23 IU/L in females.The mean annual disease progression rate was 1.2% and 3.9% for male patients with baseline ALT levels ≤ 25 IU/L(low-normal) and > 26 IU/L(highnormal),respectively(P = 0.043),and it was 1.4% and 4.8% for female patients with baseline ALT levels ≤ 22 IU/L(low-normal) and > 23 IU/L(high-normal),respectively(P = 0.023).ALT levels fluctuated during the follow-up period.During the follow-up,more patients with "high-normal" ALT levels at baseline experienced ALT elevation(> 41 IU/L) than did patients with "lownormal" ALT levels at baseline(47.7% vs 27.9%,P = 0.002).The 5 year cumulative incidence of disease progression was significantly lower in patients with persistently "low-normal" ALT levels than "high-normal" ALT levels or those who exhibited an ALT elevation > 41 U/L during the follow-up period(0%,8.3% and 34.3%,P < 0.001).CONCLUSION:A "high normal" ALT level in chronic hepatitis C patients was associated with disease progression,suggesting that the currently accepted normal threshold of serum ALT should be lowered.展开更多
The growing prevalence of metabolic dysfunction-associated steatotic liver disease(MASLD)is being driven by the obesity epidemic.The quest for solutions continues particularly with regard to early detection.This edito...The growing prevalence of metabolic dysfunction-associated steatotic liver disease(MASLD)is being driven by the obesity epidemic.The quest for solutions continues particularly with regard to early detection.This editorial comments on the utility of long-term high-normal alanine aminotransferase(ALT)in screening for MASLD.Chen et al found that new onset MASLD can be detected by repetitively high normal ALT.Implicit in this concept is the question of what should be the accepted upper limit of normal(ULN)for ALT.It was previously set at 40 IU/L based on studies that included people with subclinical liver disease but the new consensus is 30/19 U/L in healthy males/females.Thus,when Chen et al defines the ULN as 40 U/L,others may view it as excessively high.It is important to recognize the variables affecting ULN e.g.instrumentation,diurnal variations,exercise and ageing.These variables matter when the distinctions are subtle e.g.normal vs high-normal.In this regard,the utility of long-term high normal ALT as a disease marker could be enhanced by combining it with other biomarkers,imaging and MASLD genetics to create machine learning classifiers.All in all,Chen et al’s work on long-term high normal ALT as a marker of new-onset MASLD deserves merit.展开更多
The prevalence of overweighing and obese adults (defined as "adipotic" adults),has markedly increased over the world. A remarkable increase in the adipotic population urgently needs developing the regression...The prevalence of overweighing and obese adults (defined as "adipotic" adults),has markedly increased over the world. A remarkable increase in the adipotic population urgently needs developing the regression equations for predicting spirometric parameters (SPs), which are specifically applicable to adipotic adults.Unfortunately, however, the reliable equations suitable for adipotic adults have not been reported to date. Recently, Yamaguchi et al have proposed the quantitative method to estimate the effects of adiposity on deciding the SPs incorporating with age-specific contributions of various explanatory,independent variables such as age (A), standing height (H), body weight (BW),and fat fraction of body mass(F). Extending the method proposed by Yamaguchi et al, we attempted to elaborate the novel regression equations applicable for diagnosing the spirometric abnormality in adipotic adults. For accomplishing this purpose, never-smoking, adipotic adults with body mass index (BMI) over 25 kg/m^2 and no respiratory illness were recruited from the general population in Japan (n = 3696, including men: 1890 and women: 1806). Introducing the four explanatory variables of A, H, BW, and F, gender-specific and age-dependent regression equations that allowed for prescribing the SPs in adipotic adults were constructed. Comparing the results obtained for non-adipotic adults (i.e., those with normal BMI), the negative or positive impact of height on SPs was preserved in adipotic adults, as well. However, the negative impact of age on SPs was blunted in adipotic men and the positive effect of BW on SPs was impeded in adipotic men and women. The fat fraction of body mass-elicited negative impact on SPs vanished in adipotic women. These results indicate that the regression equations of SPs for adipotic adults differ significantly from those for nonadipotic adults, leading to the conclusion that the regression equations for nonadipotic adults should not be used while judging the spirometric abnormalities in adipotic adults.展开更多
A new algorithm is suggested based on the central limit theorem for generating pseudo-random numbers with a specified normal or Gaussian probability density function. The suggested algorithm is very simple but highly ...A new algorithm is suggested based on the central limit theorem for generating pseudo-random numbers with a specified normal or Gaussian probability density function. The suggested algorithm is very simple but highly accurate, with an efficiency that falls between those of the Box-Muller and von Neumann rejection methods.展开更多
Quasi-ellipsoidal gear drive is suitable for the precise flexible joint of robot,but some meshing problems of this transmission are rarely involved in the related papers.According to the two-parameter conjugate surfac...Quasi-ellipsoidal gear drive is suitable for the precise flexible joint of robot,but some meshing problems of this transmission are rarely involved in the related papers.According to the two-parameter conjugate surface theory, this article studies on the induction normal curvature and critical curves, the method of analysis is efficient for not only the quasi-ellipsoidal gear drive but also the other types of spatial gear drive.展开更多
水质数据是评估水环境与生态系统健康的关键,受限于仪器检测精度,低于检测限(limit of detection,LOD)的数据常被记录为左删失值,影响数据的完整性。实现对这类数据的有效插补,可以为水质研究提供可靠数据基础。为此,提出一种基于XGBoos...水质数据是评估水环境与生态系统健康的关键,受限于仪器检测精度,低于检测限(limit of detection,LOD)的数据常被记录为左删失值,影响数据的完整性。实现对这类数据的有效插补,可以为水质研究提供可靠数据基础。为此,提出一种基于XGBoost的低于检测限的数据插补方法(XGBoost imputation for censored data,XGIC),利用XGBoost建立非线性预测模型,拟合所有样本并计算残差;对于删失样本,以LOD作为截断点,在对应的截断正态分布上计算条件期望进行插补,并通过多次迭代提升插补准确性。模拟结果表明,与现有的4种插补方法相比,XGIC能更好地捕捉变量间的非线性关系,提高插补精度。研究结果表明,XGIC可以有效克服传统线性模型与随机森林方法的局限,为水质监测中的删失数据提供可靠插补方案。展开更多
文摘The exact classical limits for the coefficient of variation c for the normal distribution are derived. The hand-calculating approximated classical limits for c having high accuracy are given to meet practical engineering needs. Using Odeh and Owen's computational method and Brent's algorithm, the tables for the r-upper exact classical limits of coefficient of variation for normal distribution are calculated for the different confidence coefficient y, the sample size n=1(1)30,40,60,120, the sample coefficient of variation c=0.01(0.01)0.20. It is shown that if n<8,c<0.20, then the V -upper exact classical limits cu for c are slightly higher than the exact fiducial limits cu,F for c if. n>8, c<0.02,then cu-cu,f<5x10-6
文摘AIM:To investigate whether the disease progression of chronic hepatitis C patients with normal alanine aminotransferase(ALT) levels differs by ALT levels.METHODS:A total of 232 chronic hepatitis C patients with normal ALT(< 40 IU/L) were analyzed.The patients were divided into "high-normal" and "low-normal" ALT groups after determining the best predictive cutoff level associated with disease progression for each gender.The incidence of disease progression,as defined by the occurrence of an increase of ≥ 2 points in the Child-Pugh score,spontaneous bacterial peritonitis,bleeding gastric or esophageal varices,hepatic encephalopathy,the development of hepatocellular carcinoma,or death related to liver disease,were compared between the two groups.RESULTS:Baseline serum ALT levels were associatedwith disease progression for both genders.The best predictive cutoff baseline serum ALT level for disease progression was 26 IU/L in males and 23 IU/L in females.The mean annual disease progression rate was 1.2% and 3.9% for male patients with baseline ALT levels ≤ 25 IU/L(low-normal) and > 26 IU/L(highnormal),respectively(P = 0.043),and it was 1.4% and 4.8% for female patients with baseline ALT levels ≤ 22 IU/L(low-normal) and > 23 IU/L(high-normal),respectively(P = 0.023).ALT levels fluctuated during the follow-up period.During the follow-up,more patients with "high-normal" ALT levels at baseline experienced ALT elevation(> 41 IU/L) than did patients with "lownormal" ALT levels at baseline(47.7% vs 27.9%,P = 0.002).The 5 year cumulative incidence of disease progression was significantly lower in patients with persistently "low-normal" ALT levels than "high-normal" ALT levels or those who exhibited an ALT elevation > 41 U/L during the follow-up period(0%,8.3% and 34.3%,P < 0.001).CONCLUSION:A "high normal" ALT level in chronic hepatitis C patients was associated with disease progression,suggesting that the currently accepted normal threshold of serum ALT should be lowered.
文摘The growing prevalence of metabolic dysfunction-associated steatotic liver disease(MASLD)is being driven by the obesity epidemic.The quest for solutions continues particularly with regard to early detection.This editorial comments on the utility of long-term high-normal alanine aminotransferase(ALT)in screening for MASLD.Chen et al found that new onset MASLD can be detected by repetitively high normal ALT.Implicit in this concept is the question of what should be the accepted upper limit of normal(ULN)for ALT.It was previously set at 40 IU/L based on studies that included people with subclinical liver disease but the new consensus is 30/19 U/L in healthy males/females.Thus,when Chen et al defines the ULN as 40 U/L,others may view it as excessively high.It is important to recognize the variables affecting ULN e.g.instrumentation,diurnal variations,exercise and ageing.These variables matter when the distinctions are subtle e.g.normal vs high-normal.In this regard,the utility of long-term high normal ALT as a disease marker could be enhanced by combining it with other biomarkers,imaging and MASLD genetics to create machine learning classifiers.All in all,Chen et al’s work on long-term high normal ALT as a marker of new-onset MASLD deserves merit.
文摘The prevalence of overweighing and obese adults (defined as "adipotic" adults),has markedly increased over the world. A remarkable increase in the adipotic population urgently needs developing the regression equations for predicting spirometric parameters (SPs), which are specifically applicable to adipotic adults.Unfortunately, however, the reliable equations suitable for adipotic adults have not been reported to date. Recently, Yamaguchi et al have proposed the quantitative method to estimate the effects of adiposity on deciding the SPs incorporating with age-specific contributions of various explanatory,independent variables such as age (A), standing height (H), body weight (BW),and fat fraction of body mass(F). Extending the method proposed by Yamaguchi et al, we attempted to elaborate the novel regression equations applicable for diagnosing the spirometric abnormality in adipotic adults. For accomplishing this purpose, never-smoking, adipotic adults with body mass index (BMI) over 25 kg/m^2 and no respiratory illness were recruited from the general population in Japan (n = 3696, including men: 1890 and women: 1806). Introducing the four explanatory variables of A, H, BW, and F, gender-specific and age-dependent regression equations that allowed for prescribing the SPs in adipotic adults were constructed. Comparing the results obtained for non-adipotic adults (i.e., those with normal BMI), the negative or positive impact of height on SPs was preserved in adipotic adults, as well. However, the negative impact of age on SPs was blunted in adipotic men and the positive effect of BW on SPs was impeded in adipotic men and women. The fat fraction of body mass-elicited negative impact on SPs vanished in adipotic women. These results indicate that the regression equations of SPs for adipotic adults differ significantly from those for nonadipotic adults, leading to the conclusion that the regression equations for nonadipotic adults should not be used while judging the spirometric abnormalities in adipotic adults.
文摘A new algorithm is suggested based on the central limit theorem for generating pseudo-random numbers with a specified normal or Gaussian probability density function. The suggested algorithm is very simple but highly accurate, with an efficiency that falls between those of the Box-Muller and von Neumann rejection methods.
文摘Quasi-ellipsoidal gear drive is suitable for the precise flexible joint of robot,but some meshing problems of this transmission are rarely involved in the related papers.According to the two-parameter conjugate surface theory, this article studies on the induction normal curvature and critical curves, the method of analysis is efficient for not only the quasi-ellipsoidal gear drive but also the other types of spatial gear drive.
文摘水质数据是评估水环境与生态系统健康的关键,受限于仪器检测精度,低于检测限(limit of detection,LOD)的数据常被记录为左删失值,影响数据的完整性。实现对这类数据的有效插补,可以为水质研究提供可靠数据基础。为此,提出一种基于XGBoost的低于检测限的数据插补方法(XGBoost imputation for censored data,XGIC),利用XGBoost建立非线性预测模型,拟合所有样本并计算残差;对于删失样本,以LOD作为截断点,在对应的截断正态分布上计算条件期望进行插补,并通过多次迭代提升插补准确性。模拟结果表明,与现有的4种插补方法相比,XGIC能更好地捕捉变量间的非线性关系,提高插补精度。研究结果表明,XGIC可以有效克服传统线性模型与随机森林方法的局限,为水质监测中的删失数据提供可靠插补方案。
