Based on an available parking space occupancy （APSO） survey conducted in Nanjing, China, an APSO forecasting model is proposed. The APSO survey results indicate that the time series of APSO with different time-secti...Based on an available parking space occupancy （APSO） survey conducted in Nanjing, China, an APSO forecasting model is proposed. The APSO survey results indicate that the time series of APSO with different time-sections are periodical and self-similar, and the fluctuation of the APSO increases with the decrease in time-sections. Taking the short-time change behavior into account, an APSO forecasting model combined wavelet analysis and a weighted Markov chain is presented. In this model, an original APSO time series is first decomposed by wavelet analysis, and the results include low frequency signals representing the basic trends of APSO and several high frequency signals representing disturbances of the APSO. Then different Markov models are used to forecast the changes of low and high frequency signals, respectively. Finally, integrating the predicted results induces the final forecasted APSO. A case study verifies the applicability of the proposed model. The comparisons between measured and forecasted results show that the model is a competent model and its accuracy relies on real-time update of the APSO database.展开更多
AIM To investigate the diagnostic accuracy of Fibro Scan(FS) in detecting esophageal varices(EV) in cirrhotic patients.METHODS Through a systemic literature search of multiple databases, we reviewed 15 studies using e...AIM To investigate the diagnostic accuracy of Fibro Scan(FS) in detecting esophageal varices(EV) in cirrhotic patients.METHODS Through a systemic literature search of multiple databases, we reviewed 15 studies using endoscopy as a reference standard, with the data necessary to calculate pooled sensitivity(SEN) and specificity(SPE), positive and negative LR, diagnostic odds ratio(DOR) and area under receiver operating characteristics(AUROC). The quality of the studies was rated by the Quality Assessment of Diagnostic Accuracy studies-2 tool. Clinical utility of FS for EV was evaluated by a Fagan plot. Heterogeneity was explored using meta-regression and subgroup analysis. All statistical analyses were conducted via Stata12.0, MetaD isc1.4 and RevM an5.RESULTS In 15 studies(n = 2697), FS detected the presence of EV with the summary sensitivities of 84%(95%CI: 81.0%-86.0%), specificities of 62%(95%CI: 58.0%-66.0%), a positive LR of 2.3(95%CI: 1.81-2.94), a negative LR of 0.26(95%CI: 0.19-0.35), a DOR of 9.33(95%CI: 5.84-14.92) and an AUROC of 0.8262. FS diagnosed the presence of large EV with the pooled SEN of 0.78(95%CI: 75.0%-81.0%), SPE of 0.76(95%CI: 73.0%-78.0%), a positive and negative LR of 3.03(95%CI: 2.38-3.86) and 0.30(95%CI: 0.23-0.39) respectively, a summary diagnostic OR of 10.69(95%CI: 6.81-16.78), and an AUROC of 0.8321. A meta-regression and subgroup analysis indicated different etiology could serve as a potential source of heterogeneity in the diagnosis of the presence of EV group. A Deek's funnel plot suggested a low probability for publication bias.CONCLUSION Using FS to measure liver stiffness cannot provide high accuracy for the size of EV due to the various cutoff and different etiologies. These limitations preclude widespread use in clinical practice at this time; therefore, the results should be interpreted cautiously given its SEN and SPE.展开更多
基金The National Natural Science Foundation of China(No50738001)the National Basic Research Program of China (973Program) (No2006CB705501)
文摘Based on an available parking space occupancy （APSO） survey conducted in Nanjing, China, an APSO forecasting model is proposed. The APSO survey results indicate that the time series of APSO with different time-sections are periodical and self-similar, and the fluctuation of the APSO increases with the decrease in time-sections. Taking the short-time change behavior into account, an APSO forecasting model combined wavelet analysis and a weighted Markov chain is presented. In this model, an original APSO time series is first decomposed by wavelet analysis, and the results include low frequency signals representing the basic trends of APSO and several high frequency signals representing disturbances of the APSO. Then different Markov models are used to forecast the changes of low and high frequency signals, respectively. Finally, integrating the predicted results induces the final forecasted APSO. A case study verifies the applicability of the proposed model. The comparisons between measured and forecasted results show that the model is a competent model and its accuracy relies on real-time update of the APSO database.
文摘AIM To investigate the diagnostic accuracy of Fibro Scan(FS) in detecting esophageal varices(EV) in cirrhotic patients.METHODS Through a systemic literature search of multiple databases, we reviewed 15 studies using endoscopy as a reference standard, with the data necessary to calculate pooled sensitivity(SEN) and specificity(SPE), positive and negative LR, diagnostic odds ratio(DOR) and area under receiver operating characteristics(AUROC). The quality of the studies was rated by the Quality Assessment of Diagnostic Accuracy studies-2 tool. Clinical utility of FS for EV was evaluated by a Fagan plot. Heterogeneity was explored using meta-regression and subgroup analysis. All statistical analyses were conducted via Stata12.0, MetaD isc1.4 and RevM an5.RESULTS In 15 studies(n = 2697), FS detected the presence of EV with the summary sensitivities of 84%(95%CI: 81.0%-86.0%), specificities of 62%(95%CI: 58.0%-66.0%), a positive LR of 2.3(95%CI: 1.81-2.94), a negative LR of 0.26(95%CI: 0.19-0.35), a DOR of 9.33(95%CI: 5.84-14.92) and an AUROC of 0.8262. FS diagnosed the presence of large EV with the pooled SEN of 0.78(95%CI: 75.0%-81.0%), SPE of 0.76(95%CI: 73.0%-78.0%), a positive and negative LR of 3.03(95%CI: 2.38-3.86) and 0.30(95%CI: 0.23-0.39) respectively, a summary diagnostic OR of 10.69(95%CI: 6.81-16.78), and an AUROC of 0.8321. A meta-regression and subgroup analysis indicated different etiology could serve as a potential source of heterogeneity in the diagnosis of the presence of EV group. A Deek's funnel plot suggested a low probability for publication bias.CONCLUSION Using FS to measure liver stiffness cannot provide high accuracy for the size of EV due to the various cutoff and different etiologies. These limitations preclude widespread use in clinical practice at this time; therefore, the results should be interpreted cautiously given its SEN and SPE.
