The aim of this work is to construct the parameter estimators in the partial linear errors-in-variables (EV) models and explore their asymptotic properties. Unlike other related References, the assumption of known err...The aim of this work is to construct the parameter estimators in the partial linear errors-in-variables (EV) models and explore their asymptotic properties. Unlike other related References, the assumption of known error covariance matrix is removed when the sample can be repeatedly drawn at each designed point from the model. The estimators of interested regression parameters, and the model error variance, as well as the nonparametric function, are constructed. Under some regular conditions, all of the estimators prove strongly consistent. Meanwhile, the asymptotic normality for the estimator of regression parameter is also presented. A simulation study is reported to illustrate our asymptotic results.展开更多
Background Periodontitis and osteoporosis are one of the frequently encountered diseases in post-menopausal women. Estrogen receptors （ERs） regulated bone metabolism. To investigate the possible effect of ER-elpha ...Background Periodontitis and osteoporosis are one of the frequently encountered diseases in post-menopausal women. Estrogen receptors （ERs） regulated bone metabolism. To investigate the possible effect of ER-elpha （a） gene polymorphisms on bone mineral density （BMD） in pre- and post-menopausal Chinese women with chronic periodontitis （CP）, we provided sufficient quantitative information concerning the correlation between ER gene polymorphisms and BMD in periodontitis. Methods Sixty-five post-menopausal and eighty pre-menopausal CP women, and sixty post-menopausal healthy individuals were recruited in this study. Genomic DNA was extracted from oral mucosa swab sample of each subject by the Chelex-100 method. Determination of the ER-a polymorphisms was performed by polymerese chain reaction-restriction fragment length polymorphism （PCR-RFLP） technique with Xbal and Pvull enzyme. The index for periodontal examination includes clinical attachment loss （CAL） and probing pocket depth （PPD）. BMD was measured by dual-energy X-ray absorptiometry （DEXA）. Results There were no significant differences between the ER-α genotypes of Pvull and Xbal and BMD in post-menopausal and pre-menopausal CP patients, respectively （P 〉0.05）. However, there was association between pre- and post-menopausal CP patients at BMD of lumbar spine L2-L4 （P=0.027） and Ward＇s BMD （P=0.004）. Furthermore, the post-menopausal CP women who carried Pvull TT genotype presented significantly lower Ward＇s BMD than the pre-menopausal CP women （P=-0.007）, meanwhile, the post-menopausal CP women who carried Xbal AA genotype presented significantly lower spine L2-L4 BMD than the pre-menopausal CP women （P=0.003）. Conclusions ER-α gene polymorphisms may be a susceptible indicator for BMD variation of lumbar spine L2-L4 and Ward in Chinese pre- and post-menopausal women patients with CP.展开更多
This article mainly discusses the admissibility of quadratic estimate of covariance in pseudoelliptical distribution. Under the quadratic loss function, the necessary and sufficient conditions that a quadratic estimat...This article mainly discusses the admissibility of quadratic estimate of covariance in pseudoelliptical distribution. Under the quadratic loss function, the necessary and sufficient conditions that a quadratic estimator is an admissible estimator of covariance in the class of quadratic estimators are obtained. A complete class of the quadratic estimator class is also given.展开更多
A class of robust location estimators called weighted randomly trimmed means are introduced and not only their consistency and asymptotic normality are proved, but their influence functions, asymptotic variances and b...A class of robust location estimators called weighted randomly trimmed means are introduced and not only their consistency and asymptotic normality are proved, but their influence functions, asymptotic variances and breakdown points are also derived. They possess the same breakdown points as the median, and some of them own higher asymptotic relative efficiencies at the heavy-tailed distributions than some other well-known location estimators; whereas the trimmed means, Winsorized means and Huber＇s M-estimator possess higher asymptotic relative efficiencies at the light-tailed distributions, in which Huber＇s M-estimator is the most robust.展开更多
基金This work was partially supported by the National Natural Science Foundation of China(Grant No.10071009)Research Foundation of Doctorial Programme(Grant No.20020027010)the Excellent Young Teacher Programme of the Ministry of Educatioin of China
文摘The aim of this work is to construct the parameter estimators in the partial linear errors-in-variables (EV) models and explore their asymptotic properties. Unlike other related References, the assumption of known error covariance matrix is removed when the sample can be repeatedly drawn at each designed point from the model. The estimators of interested regression parameters, and the model error variance, as well as the nonparametric function, are constructed. Under some regular conditions, all of the estimators prove strongly consistent. Meanwhile, the asymptotic normality for the estimator of regression parameter is also presented. A simulation study is reported to illustrate our asymptotic results.
基金This study was supported in part by the a grant from National Natural Science Foundation of China （No. 30572069）.Acknowledgements： The authors are grateful to Prof. LIU Jia-yun, Department of Clinical Molecular Biology, Xijing Hospital, Fourth Military Medical University, for his technical advice.
文摘Background Periodontitis and osteoporosis are one of the frequently encountered diseases in post-menopausal women. Estrogen receptors （ERs） regulated bone metabolism. To investigate the possible effect of ER-elpha （a） gene polymorphisms on bone mineral density （BMD） in pre- and post-menopausal Chinese women with chronic periodontitis （CP）, we provided sufficient quantitative information concerning the correlation between ER gene polymorphisms and BMD in periodontitis. Methods Sixty-five post-menopausal and eighty pre-menopausal CP women, and sixty post-menopausal healthy individuals were recruited in this study. Genomic DNA was extracted from oral mucosa swab sample of each subject by the Chelex-100 method. Determination of the ER-a polymorphisms was performed by polymerese chain reaction-restriction fragment length polymorphism （PCR-RFLP） technique with Xbal and Pvull enzyme. The index for periodontal examination includes clinical attachment loss （CAL） and probing pocket depth （PPD）. BMD was measured by dual-energy X-ray absorptiometry （DEXA）. Results There were no significant differences between the ER-α genotypes of Pvull and Xbal and BMD in post-menopausal and pre-menopausal CP patients, respectively （P 〉0.05）. However, there was association between pre- and post-menopausal CP patients at BMD of lumbar spine L2-L4 （P=0.027） and Ward＇s BMD （P=0.004）. Furthermore, the post-menopausal CP women who carried Pvull TT genotype presented significantly lower Ward＇s BMD than the pre-menopausal CP women （P=-0.007）, meanwhile, the post-menopausal CP women who carried Xbal AA genotype presented significantly lower spine L2-L4 BMD than the pre-menopausal CP women （P=0.003）. Conclusions ER-α gene polymorphisms may be a susceptible indicator for BMD variation of lumbar spine L2-L4 and Ward in Chinese pre- and post-menopausal women patients with CP.
基金The research was partially supported by the Doctoral Programme of Higher Education(No.20020027010)of China.
文摘This article mainly discusses the admissibility of quadratic estimate of covariance in pseudoelliptical distribution. Under the quadratic loss function, the necessary and sufficient conditions that a quadratic estimator is an admissible estimator of covariance in the class of quadratic estimators are obtained. A complete class of the quadratic estimator class is also given.
基金This research is supported by the National Natural Science Foundation of China （Grant No. 10371012, 10231030,and 40574020）.
文摘A class of robust location estimators called weighted randomly trimmed means are introduced and not only their consistency and asymptotic normality are proved, but their influence functions, asymptotic variances and breakdown points are also derived. They possess the same breakdown points as the median, and some of them own higher asymptotic relative efficiencies at the heavy-tailed distributions than some other well-known location estimators; whereas the trimmed means, Winsorized means and Huber＇s M-estimator possess higher asymptotic relative efficiencies at the light-tailed distributions, in which Huber＇s M-estimator is the most robust.
