Background: This study aimed to explore the best screening measure of myopia and its associated optimal referral criteria for children aged between 6 and 16.Methods: After informed consent of cycloplegia was obtained,...Background: This study aimed to explore the best screening measure of myopia and its associated optimal referral criteria for children aged between 6 and 16.Methods: After informed consent of cycloplegia was obtained, a total of 6,321 children aged between 6 and 16 from 53 primary or junior middle schools in Jiading District of Shanghai were included in our populationbased study. Receiver operating characteristic(ROC) curve was performed to determine the best cutoff points, sensitivities and specii cities of different screening tests, including uncorrected visual acuity(UCVA), noncycloplegic autorefraction(NCAR) and the combination of these two tests.Results: There was significant difference in prevalence of myopia between boys and girls(χ~2=6.358, P=0.012). Compared with children of low age, the prevalence of older children was significantly higher(χ~2=1,386.404, P<0.001). For the combination of UCVA and NCAR, the best cutoff point was UCVA less than or equal to 0.2 logarithm of minimum angle of resolution(MAR)(20/30) and NCAR spherical equivalent refraction(SER) less than or equal to -0.75 diopters(D), with associated sensitivity and specificity of 75.0% and 85.0%, respectively, which were higher than those of UCVA and NCAR alone. After stratified by age, the best cutof points were varied among children. The accuracy for children aged between 9 and 12 was higher than that for other ages.Conclusions: The best screening measure of myopia was the combination of UCVA and NCAR. The optimal referral criteria of myopia for children should be age-determined.展开更多
LA-ICPMS zircon U-Pb dating has been greatly advanced and widely applied in the past decade because it is a cheap and fast technique.The internal error of LA-ICPMS zircon U-Pb dating can be better than 1%,but reproduc...LA-ICPMS zircon U-Pb dating has been greatly advanced and widely applied in the past decade because it is a cheap and fast technique.The internal error of LA-ICPMS zircon U-Pb dating can be better than 1%,but reproducibility(accuracy)is relatively poor.In order to quantitatively assess the accuracy of this technique,zircons from two dioritic rocks,a Mesozoic dioritic microgranular enclave(FS06)and a Neoproterozoic diorite(WC09-32),were dated independently in eight laboratories using SIMS and LA-ICPMS.Results of three SIMS analyses on FS06 and WC09-2 are indistinguishable within error and give a best estimate of the crystallization age of 132.2 and 760.5 Ma(reproducibility is^1%,2RSD),respectively.Zircon U-Pb ages determined by LA-ICPMS in six laboratories vary from 128.3±1.0 to 135.0±0.9 Ma(2SE)for FS06 and from 742.9±3.1 to777.8±4.7 Ma(2SE)for WC09-32,suggesting a reproducibility of^4%(2RSD).Uncertainty produced during LA-ICPMS zircon U-Pb analyses comes from multiple sources,including uncertainty in the isotopic ratio measurements,uncertainty in the fractionation factor calculation using an external standard,uncertainty in the age determination as a result of common lead correction,age uncertainty of the external standards and uncertainty in the data reduction.Result of our study suggests that the uncertainty of LA-ICPMS zircon U-Pb dating is approximately 4%(2RSD).The uncertainty in age determination must be considered in order to interpret LA-ICPMS zircon U-Pb data rationally.展开更多
We present an epidemic model which can incorporate essential biological detail as well as the intrinsic demographic stochastieity of the epidemic process, yet is very simple, enabling rapid generation of a large numbe...We present an epidemic model which can incorporate essential biological detail as well as the intrinsic demographic stochastieity of the epidemic process, yet is very simple, enabling rapid generation of a large number of simulations, A deterministic version of the model is also derived, in the limit of infinitely large populations, and a final-size formula for the deterministic model is proved. A key advantage of the model proposed is that it is possible to write down an explicit likelihood functions for it, which enables a systematic procedure for fitting parameters to real incidence data, using maximum likelihood.展开更多
文摘Background: This study aimed to explore the best screening measure of myopia and its associated optimal referral criteria for children aged between 6 and 16.Methods: After informed consent of cycloplegia was obtained, a total of 6,321 children aged between 6 and 16 from 53 primary or junior middle schools in Jiading District of Shanghai were included in our populationbased study. Receiver operating characteristic(ROC) curve was performed to determine the best cutoff points, sensitivities and specii cities of different screening tests, including uncorrected visual acuity(UCVA), noncycloplegic autorefraction(NCAR) and the combination of these two tests.Results: There was significant difference in prevalence of myopia between boys and girls(χ~2=6.358, P=0.012). Compared with children of low age, the prevalence of older children was significantly higher(χ~2=1,386.404, P<0.001). For the combination of UCVA and NCAR, the best cutoff point was UCVA less than or equal to 0.2 logarithm of minimum angle of resolution(MAR)(20/30) and NCAR spherical equivalent refraction(SER) less than or equal to -0.75 diopters(D), with associated sensitivity and specificity of 75.0% and 85.0%, respectively, which were higher than those of UCVA and NCAR alone. After stratified by age, the best cutof points were varied among children. The accuracy for children aged between 9 and 12 was higher than that for other ages.Conclusions: The best screening measure of myopia was the combination of UCVA and NCAR. The optimal referral criteria of myopia for children should be age-determined.
基金supported by the State Key Laboratory of Lithospheric EvolutionThe analyses at the University of Newcastle were financially supported by the Analytical&Biomolecular Research Facility(ABRF)unitsupported by the National Basic Research Program of China(Grant Nos.2012CB416702)
文摘LA-ICPMS zircon U-Pb dating has been greatly advanced and widely applied in the past decade because it is a cheap and fast technique.The internal error of LA-ICPMS zircon U-Pb dating can be better than 1%,but reproducibility(accuracy)is relatively poor.In order to quantitatively assess the accuracy of this technique,zircons from two dioritic rocks,a Mesozoic dioritic microgranular enclave(FS06)and a Neoproterozoic diorite(WC09-32),were dated independently in eight laboratories using SIMS and LA-ICPMS.Results of three SIMS analyses on FS06 and WC09-2 are indistinguishable within error and give a best estimate of the crystallization age of 132.2 and 760.5 Ma(reproducibility is^1%,2RSD),respectively.Zircon U-Pb ages determined by LA-ICPMS in six laboratories vary from 128.3±1.0 to 135.0±0.9 Ma(2SE)for FS06 and from 742.9±3.1 to777.8±4.7 Ma(2SE)for WC09-32,suggesting a reproducibility of^4%(2RSD).Uncertainty produced during LA-ICPMS zircon U-Pb analyses comes from multiple sources,including uncertainty in the isotopic ratio measurements,uncertainty in the fractionation factor calculation using an external standard,uncertainty in the age determination as a result of common lead correction,age uncertainty of the external standards and uncertainty in the data reduction.Result of our study suggests that the uncertainty of LA-ICPMS zircon U-Pb dating is approximately 4%(2RSD).The uncertainty in age determination must be considered in order to interpret LA-ICPMS zircon U-Pb data rationally.
文摘We present an epidemic model which can incorporate essential biological detail as well as the intrinsic demographic stochastieity of the epidemic process, yet is very simple, enabling rapid generation of a large number of simulations, A deterministic version of the model is also derived, in the limit of infinitely large populations, and a final-size formula for the deterministic model is proved. A key advantage of the model proposed is that it is possible to write down an explicit likelihood functions for it, which enables a systematic procedure for fitting parameters to real incidence data, using maximum likelihood.
