AIM： To identify clinical parameters, and develop an Upper Gastrointesinal Bleeding （UGIB） Etiology Score for predicting the types of UGIB and validate the score. METHODS： Patients with UGIB who underwent endoscop...AIM： To identify clinical parameters, and develop an Upper Gastrointesinal Bleeding （UGIB） Etiology Score for predicting the types of UGIB and validate the score. METHODS： Patients with UGIB who underwent endoscopy within 72 h were enrolled. Clinical and basic laboratory parameters were prospectively collected. Predictive factors for the types of UGIB were identified by univariate and multivariate analyses and were used to generate the UGIB Etiology Score. The best cutoff of the score was defined from the receiver operating curve and prospectively validated in another set of patients with UGIB. RESULTS： Among 261 patients with UGIB, 47 （18%） had variceal and 214 （82%） had non-variceal bleeding. Univariate analysis identified 27 distinct parameters significantly associated with the types of UGIB. Logistic regression analysis identified only 3 independent factors for predicting variceal bleeding; previous diagnosis of cirrhosis or signs of chronic liver disease （OR 22.4, 95% CI 8.3-60.4, P 〈 0.001）, red vomitus （OR 4.6, 95% CI 1.8-11.9, P = 0.02）, and red nasogastric （NG） aspirate （OR 3.3, 95% CI 1.3-8.3, P = 0.011）. The UGIB Etiology Score was calculated from （3.1× previous diagnosis of cirrhosis or signs of chronic liver disease） ＋ （1.5× red vomitus） ＋ （1.2× red NG aspirate）, when 1 and 0 are used for the presence and absence of each factor, respectively. Using a cutoff ≥ 3.1, the sensitivity, specificity, accuracy, positive predictive value （PPV）, and negative predictive value （NPV） in predicting variceal bleeding were 85%, 81%, 82%, 50%, and 96%, respectively. The score was prospectively validated in cases （46 variceal and 149 another set of 195 UGIB non-variceal bleeding）. The PPV and NPV of a score ≥ 3.1 for variceal bleeding were 79% and 97%, respectively. CONCLUSION： The UGIB Etiology Score, composed of 3 parameters, using a cutoff ≥ 3.1 accurately predicted variceal bleeding and may help to guide the choice of initial therapy for UGIB before endoscopy.展开更多
Based on the coexistence of the Blandford-Znajek and magnetic coupling processes in black hole （BH） accretion disc, a multi-parameter model for jet powers and radio loudnees of active galactic nuclei （AGNs） is stu...Based on the coexistence of the Blandford-Znajek and magnetic coupling processes in black hole （BH） accretion disc, a multi-parameter model for jet powers and radio loudnees of active galactic nuclei （AGNs） is studied. It turns out that radio-loudnees of AGNs couM be governed by five parameters： （i） the BH spin, （ii） a power-law index of the variation of the magnetic field on the disc; （iii） a parameter determining the position of the inner edge of the disc, （iv） the ratio of the pressure of the magnetic field on the horizon to the ram pressure of the innermost parts of an accretion flow, and （v） the ratio of the angular velocity of the open field lines to that of the horizon. The observed dichotomy between radio-loud and radio-quiet AGNs is well interpreted by the effects of the above parameters. Furthermore, we discuss the derivative of radio loudness of AGNs with respect to each parameter separately. In addition, the effect of the screw instability on radio loudness of AGNs is discussed.展开更多
A model of correcting the nonlinear error of photoelectric displacement sensor was established based on the least square support vector machine.The parameters of the correcting nonlinear model,such as penalty factor a...A model of correcting the nonlinear error of photoelectric displacement sensor was established based on the least square support vector machine.The parameters of the correcting nonlinear model,such as penalty factor and kernel parameter,were optimized by chaos genetic algorithm.And the nonlinear correction of photoelectric displacement sensor based on least square support vector machine was applied.The application results reveal that error of photoelectric displacement sensor is less than 1.5%,which is rather satisfactory for nonlinear correction of photoelectric displacement sensor.展开更多
The post-AGB star J004441 is the first and the only one CEMP-r/s star found in SMC. Herein, we investigate the observed abun- dance pattern of the heavy elements using our parametric model. A consistent fitting result...The post-AGB star J004441 is the first and the only one CEMP-r/s star found in SMC. Herein, we investigate the observed abun- dance pattern of the heavy elements using our parametric model. A consistent fitting results was obtained for the sample star. Based on the low r = 0.08, the s-process nucleosynthesis occurred in the interior is supposed to belong to the single neutron-exposure v9 ,1/2 mbarn-1 supports a higher efficiency of the s-process nucleosynthesis relative to event. The median value of τ0 =0.44（T9/0.348）mbarn-1 supports a higher efficiency of the s-process nucleosynthesis relative to J004441 than that of the solar system, however, the value is not sufficiently high to favor the formation of a lead star. Thus, J004441 does not belong to lead star group. The large Cs value of J004441 supports the intrinsic characteristic of the s-enrichment. The Cr value is similar with that found in halo CEMP-r/s stars, which indicates that the r-process contributions is critical during heavy element enrichment. This star has a metallicity of [Fe/H] = -1.34, which is larger than that of Galaxy halo CEMP-r/s stars. The reason may be because of the different history of metallicity enrichment between the SMC and the Galaxy halo.展开更多
This paper derives some uniform convergence rates for kernel regression of some index functions that may depend on infinite dimensional parameter. The rates of convergence are computed for independent, strongly mixing...This paper derives some uniform convergence rates for kernel regression of some index functions that may depend on infinite dimensional parameter. The rates of convergence are computed for independent, strongly mixing and weakly dependent data respectively. These results extend the existing literature and are useful for the derivation of large sample properties of the estimators in some semiparametric and nonparametric models.展开更多
文摘AIM： To identify clinical parameters, and develop an Upper Gastrointesinal Bleeding （UGIB） Etiology Score for predicting the types of UGIB and validate the score. METHODS： Patients with UGIB who underwent endoscopy within 72 h were enrolled. Clinical and basic laboratory parameters were prospectively collected. Predictive factors for the types of UGIB were identified by univariate and multivariate analyses and were used to generate the UGIB Etiology Score. The best cutoff of the score was defined from the receiver operating curve and prospectively validated in another set of patients with UGIB. RESULTS： Among 261 patients with UGIB, 47 （18%） had variceal and 214 （82%） had non-variceal bleeding. Univariate analysis identified 27 distinct parameters significantly associated with the types of UGIB. Logistic regression analysis identified only 3 independent factors for predicting variceal bleeding; previous diagnosis of cirrhosis or signs of chronic liver disease （OR 22.4, 95% CI 8.3-60.4, P 〈 0.001）, red vomitus （OR 4.6, 95% CI 1.8-11.9, P = 0.02）, and red nasogastric （NG） aspirate （OR 3.3, 95% CI 1.3-8.3, P = 0.011）. The UGIB Etiology Score was calculated from （3.1× previous diagnosis of cirrhosis or signs of chronic liver disease） ＋ （1.5× red vomitus） ＋ （1.2× red NG aspirate）, when 1 and 0 are used for the presence and absence of each factor, respectively. Using a cutoff ≥ 3.1, the sensitivity, specificity, accuracy, positive predictive value （PPV）, and negative predictive value （NPV） in predicting variceal bleeding were 85%, 81%, 82%, 50%, and 96%, respectively. The score was prospectively validated in cases （46 variceal and 149 another set of 195 UGIB non-variceal bleeding）. The PPV and NPV of a score ≥ 3.1 for variceal bleeding were 79% and 97%, respectively. CONCLUSION： The UGIB Etiology Score, composed of 3 parameters, using a cutoff ≥ 3.1 accurately predicted variceal bleeding and may help to guide the choice of initial therapy for UGIB before endoscopy.
基金The project supported by National Natural Science Foundation of China under Grant Nos. 10173004, 10373006, and 10121503
文摘Based on the coexistence of the Blandford-Znajek and magnetic coupling processes in black hole （BH） accretion disc, a multi-parameter model for jet powers and radio loudnees of active galactic nuclei （AGNs） is studied. It turns out that radio-loudnees of AGNs couM be governed by five parameters： （i） the BH spin, （ii） a power-law index of the variation of the magnetic field on the disc; （iii） a parameter determining the position of the inner edge of the disc, （iv） the ratio of the pressure of the magnetic field on the horizon to the ram pressure of the innermost parts of an accretion flow, and （v） the ratio of the angular velocity of the open field lines to that of the horizon. The observed dichotomy between radio-loud and radio-quiet AGNs is well interpreted by the effects of the above parameters. Furthermore, we discuss the derivative of radio loudness of AGNs with respect to each parameter separately. In addition, the effect of the screw instability on radio loudness of AGNs is discussed.
基金Project(50925727) supported by the National Fund for Distinguish Young Scholars of ChinaProject(60876022) supported by the National Natural Science Foundation of China+1 种基金Project(2010FJ4141) supported by Hunan Provincial Science and Technology Foundation,ChinaProject supported by the Fund of the Key Construction Academic Subject (Optics) of Hunan Province,China
文摘A model of correcting the nonlinear error of photoelectric displacement sensor was established based on the least square support vector machine.The parameters of the correcting nonlinear model,such as penalty factor and kernel parameter,were optimized by chaos genetic algorithm.And the nonlinear correction of photoelectric displacement sensor based on least square support vector machine was applied.The application results reveal that error of photoelectric displacement sensor is less than 1.5%,which is rather satisfactory for nonlinear correction of photoelectric displacement sensor.
基金supported by the National Natural Science Foundation of China(Grant Nos.U1231119,11273011,11390371,11003002,11021504 and 10973016)the China Postdoctoral Science Foundation(Grant No.2013M531587)the Natural Science Foundation of Hebei Province(Grant No.A2011205102)
文摘The post-AGB star J004441 is the first and the only one CEMP-r/s star found in SMC. Herein, we investigate the observed abun- dance pattern of the heavy elements using our parametric model. A consistent fitting results was obtained for the sample star. Based on the low r = 0.08, the s-process nucleosynthesis occurred in the interior is supposed to belong to the single neutron-exposure v9 ,1/2 mbarn-1 supports a higher efficiency of the s-process nucleosynthesis relative to event. The median value of τ0 =0.44（T9/0.348）mbarn-1 supports a higher efficiency of the s-process nucleosynthesis relative to J004441 than that of the solar system, however, the value is not sufficiently high to favor the formation of a lead star. Thus, J004441 does not belong to lead star group. The large Cs value of J004441 supports the intrinsic characteristic of the s-enrichment. The Cr value is similar with that found in halo CEMP-r/s stars, which indicates that the r-process contributions is critical during heavy element enrichment. This star has a metallicity of [Fe/H] = -1.34, which is larger than that of Galaxy halo CEMP-r/s stars. The reason may be because of the different history of metallicity enrichment between the SMC and the Galaxy halo.
基金National Natural Science Foundation of China (Grant No. 70971082)Shanghai Leading Academic Discipline Project at Shanghai University of Finance and Economics (SHUFE) (Grant No. B803)Key Laboratory of Mathematical Economics (SHUFE), Ministry of Education
文摘This paper derives some uniform convergence rates for kernel regression of some index functions that may depend on infinite dimensional parameter. The rates of convergence are computed for independent, strongly mixing and weakly dependent data respectively. These results extend the existing literature and are useful for the derivation of large sample properties of the estimators in some semiparametric and nonparametric models.
