A large number of debris flows occurred in the Wenchuan earthquake zone after the 12 May 2008 earthquake.The risks posed by these debris flows were rather high.An appropriate model is required to predict the possible ...A large number of debris flows occurred in the Wenchuan earthquake zone after the 12 May 2008 earthquake.The risks posed by these debris flows were rather high.An appropriate model is required to predict the possible runout distance and impacted area.This paper describes a study on the runout characteristics of the debris flows that occurred in the Wenchuan earthquake zone over the past four years.A total of 120 debris flows are analyzed.Separate multivariate regression models are established for the runout distances of hill-slope debris flows and channelized debris flows.The control variables include type of debris flow,debris flow volume,and elevation difference.Comparison of the debris flows occurring before and after the earthquake shows that the runout distance increased after the earthquake due to sufficient material supply and increased mobility of the source materials.In addition,the runout distances of annual debris flow events in 2008,2010 and 2011 are analyzed and compared.There is a tendency that the runout distance decreases over time due to the decreasing source material volume and possible changes of debris flow type.Comparison between the debris flows in the earthquake zone and the debris flows in Swiss Alps,Canada,Austria,and Japan shows that the former have a smaller mobility.展开更多
AIM:To examine the association between parity and gastric cancer (the cases are almost all premenopausal women) risk in a cohort of young parous women.METHODS:The study cohort consisted of all women with a record of a...AIM:To examine the association between parity and gastric cancer (the cases are almost all premenopausal women) risk in a cohort of young parous women.METHODS:The study cohort consisted of all women with a record of a first and singleton childbirth in the Birth Register between 1978 and 1987.We tracked each woman from the time of her first childbirth to December 31,2008.Their vital status was ascertained by linking records to the computerized mortality database.Cox proportional hazard regression models were used to estimate hazard ratios of death from gastric cancer associated with parity.RESULTS:There were 1090 gastric cancer deaths (85.87% of them were premenopausal) during 33686828 person-years of follow-up.The mortality rate of gastric cancer was 3.24 cases per 100000 person-years.A trend of increasing risk of gastric cancer was seen with increasing parity.The adjusted hazard ratio was 1.24 [confidence interval (95% CI):1.02-1.50] for women who had borne two to three children,and 1.32 (95% CI:1.01-1.72) for women with four or more births,when compared with women who had given birth to only one child.CONCLUSION:These results suggest that higher parity may increase the risk of death from gastric cancer among premenopausal women.展开更多
Objective To determine the incidence, course, potential risk factors, and outcomes of noninfectious fever developed in patients after aortic surgery. Methods Patients who received operation for aortic aneurysm or dis...Objective To determine the incidence, course, potential risk factors, and outcomes of noninfectious fever developed in patients after aortic surgery. Methods Patients who received operation for aortic aneurysm or dissection in our center from January 2006 to January 2008 were reviewed. Patients who met one of the following criteria were excluded： having a known source of infection during hospitalization; having a preoperative oral temperature greater than or equal to 38.0℃; undertaking emergency surgery; having incomplete data. Univariate analysis was performed in patients with noninfectious postoperative fever and those without, with respect to demographics, intraoperative data, etc. Risk factors for postoperative fever were considered for the muhivariate logistic regression model if they had a P value less than 0.10 in the univariate analysis. Results Totally 463 patients undergoing aortic surgery were enrolled for full review. Among them, 345 （74.5%） patients had noninfectious postoperative fever, the other 118 （25.5%） patients didn＇t develop postoperative fever. Univariate analysis demonstrated that several risk factors were associated with the development of noninfectious postoperative fever, including weight, surgical procedure, minimum intraoperative bladder temperature, temperature upon intensive care unit （ICU） admission, discharge, and during ICU stay, as well as blood transfusion. In a further multivariate analysis, surgical site of thoracic and thoracoabdominal aorta （odds ratio： 4.861; 95% confidence interval： 3.029-5.801; P=0.004）, lower minimum intraoperative bladder temperature （odds ratio： 1.117; 95% confidence interval： 1.01-1.24; P=0.04）, and higher temperature on admission to the ICU （odds ratio： 2.57; 95% confidence interval： 1.28-5.18; P=0.008） were found to be significant predictors for noninfectious postoperative fever. No difference was found between the febrile and afebrile patients with regard to postoperative hospitalization duration （P=0.558） or total medical costs （P=0.896）. Conclusion Noninfectious postoperative fever following aortic surgery is very common and closely related with perioperative interventions.展开更多
This paper considers two estimators of θ= g（x） in a nonparametric regression model Y = g（x） ＋ ε（x∈ （0, 1）p） with missing responses： Imputation and inverse probability weighted esti- mators. Asymptotic nor...This paper considers two estimators of θ= g（x） in a nonparametric regression model Y = g（x） ＋ ε（x∈ （0, 1）p） with missing responses： Imputation and inverse probability weighted esti- mators. Asymptotic normality of the two estimators is established, which is used to construct normal approximation based confidence intervals on θ.展开更多
Empirical likelihood has been found very useful in many different occasions. It usually runs into serious computational difficulties while jackknife empirical likelihood （JEL） is shown to be effective when applied t...Empirical likelihood has been found very useful in many different occasions. It usually runs into serious computational difficulties while jackknife empirical likelihood （JEL） is shown to be effective when applied to some complicated statistics. In this paper, to test the difference between coefficients of two linear regression models, the authors apply JEL to construct the confidence regions. Based on the 3EL ratio test, a version of Wilks＇ theorem is developed. Furthermore, to improve the coverage accuracy of confidence regions, a Bartlett correction is applied. Simulation studies are carried out to show the effectiveness of the proposed method in aspects of coverage accuracy. A real data set is analyzed with the proposed method as an example.展开更多
基金the support from Sichuan Provincial Department of Transportation and Communicationsthe National Basic Research Program of China (Grant No.2011CB013506)the Research Grants Council of the Hong Kong SAR (Grant No.622210)
文摘A large number of debris flows occurred in the Wenchuan earthquake zone after the 12 May 2008 earthquake.The risks posed by these debris flows were rather high.An appropriate model is required to predict the possible runout distance and impacted area.This paper describes a study on the runout characteristics of the debris flows that occurred in the Wenchuan earthquake zone over the past four years.A total of 120 debris flows are analyzed.Separate multivariate regression models are established for the runout distances of hill-slope debris flows and channelized debris flows.The control variables include type of debris flow,debris flow volume,and elevation difference.Comparison of the debris flows occurring before and after the earthquake shows that the runout distance increased after the earthquake due to sufficient material supply and increased mobility of the source materials.In addition,the runout distances of annual debris flow events in 2008,2010 and 2011 are analyzed and compared.There is a tendency that the runout distance decreases over time due to the decreasing source material volume and possible changes of debris flow type.Comparison between the debris flows in the earthquake zone and the debris flows in Swiss Alps,Canada,Austria,and Japan shows that the former have a smaller mobility.
基金Supported by A grant from the National Science Council,Executive Yuan,Taiwan,No.NSC-94-2314-B-037-056
文摘AIM:To examine the association between parity and gastric cancer (the cases are almost all premenopausal women) risk in a cohort of young parous women.METHODS:The study cohort consisted of all women with a record of a first and singleton childbirth in the Birth Register between 1978 and 1987.We tracked each woman from the time of her first childbirth to December 31,2008.Their vital status was ascertained by linking records to the computerized mortality database.Cox proportional hazard regression models were used to estimate hazard ratios of death from gastric cancer associated with parity.RESULTS:There were 1090 gastric cancer deaths (85.87% of them were premenopausal) during 33686828 person-years of follow-up.The mortality rate of gastric cancer was 3.24 cases per 100000 person-years.A trend of increasing risk of gastric cancer was seen with increasing parity.The adjusted hazard ratio was 1.24 [confidence interval (95% CI):1.02-1.50] for women who had borne two to three children,and 1.32 (95% CI:1.01-1.72) for women with four or more births,when compared with women who had given birth to only one child.CONCLUSION:These results suggest that higher parity may increase the risk of death from gastric cancer among premenopausal women.
文摘Objective To determine the incidence, course, potential risk factors, and outcomes of noninfectious fever developed in patients after aortic surgery. Methods Patients who received operation for aortic aneurysm or dissection in our center from January 2006 to January 2008 were reviewed. Patients who met one of the following criteria were excluded： having a known source of infection during hospitalization; having a preoperative oral temperature greater than or equal to 38.0℃; undertaking emergency surgery; having incomplete data. Univariate analysis was performed in patients with noninfectious postoperative fever and those without, with respect to demographics, intraoperative data, etc. Risk factors for postoperative fever were considered for the muhivariate logistic regression model if they had a P value less than 0.10 in the univariate analysis. Results Totally 463 patients undergoing aortic surgery were enrolled for full review. Among them, 345 （74.5%） patients had noninfectious postoperative fever, the other 118 （25.5%） patients didn＇t develop postoperative fever. Univariate analysis demonstrated that several risk factors were associated with the development of noninfectious postoperative fever, including weight, surgical procedure, minimum intraoperative bladder temperature, temperature upon intensive care unit （ICU） admission, discharge, and during ICU stay, as well as blood transfusion. In a further multivariate analysis, surgical site of thoracic and thoracoabdominal aorta （odds ratio： 4.861; 95% confidence interval： 3.029-5.801; P=0.004）, lower minimum intraoperative bladder temperature （odds ratio： 1.117; 95% confidence interval： 1.01-1.24; P=0.04）, and higher temperature on admission to the ICU （odds ratio： 2.57; 95% confidence interval： 1.28-5.18; P=0.008） were found to be significant predictors for noninfectious postoperative fever. No difference was found between the febrile and afebrile patients with regard to postoperative hospitalization duration （P=0.558） or total medical costs （P=0.896）. Conclusion Noninfectious postoperative fever following aortic surgery is very common and closely related with perioperative interventions.
基金This research is supported by he National Natural Science Foundation of China under Grant Nos. 10661003 and 10971038, and the Natural Science Foundation of Guangxi under Grant No. 2010GXNSFA013117.
文摘This paper considers two estimators of θ= g（x） in a nonparametric regression model Y = g（x） ＋ ε（x∈ （0, 1）p） with missing responses： Imputation and inverse probability weighted esti- mators. Asymptotic normality of the two estimators is established, which is used to construct normal approximation based confidence intervals on θ.
基金supported by the China Postdoctoral Science Foundation under Grant No.2014M550799the National Science Foundation of China under Grant No.11401561
文摘Empirical likelihood has been found very useful in many different occasions. It usually runs into serious computational difficulties while jackknife empirical likelihood （JEL） is shown to be effective when applied to some complicated statistics. In this paper, to test the difference between coefficients of two linear regression models, the authors apply JEL to construct the confidence regions. Based on the 3EL ratio test, a version of Wilks＇ theorem is developed. Furthermore, to improve the coverage accuracy of confidence regions, a Bartlett correction is applied. Simulation studies are carried out to show the effectiveness of the proposed method in aspects of coverage accuracy. A real data set is analyzed with the proposed method as an example.
