Background: We performed a systematic review and meta-analysis to assess the accuracy of 18F-fluorodeoxyglucose positron emission tomography with computer tomography (18F-FDG PET/CT) for detection of regional lymph node metastasis in esophageal squamous cell carcinoma in per-patient and per-nodal station basis. Methods: Electronic databases were researched for studies assessing the sensitivity and specificity of PET/ CT to detect the regional lymph node metastasis published between January 2006 and December 2017 on esophageal squamous cell carcinoma. STATA software was performed to assess the sensitivity, specificity, positive likelihood ratio (PLR), negative likelihood ratio (NLR), diagnostic odd ratio (DOR) and summary receiver operating characteristic (SROC) curve. The Quality Assessment of Diagnostic Accuracy Studies 2 (QUADAS-2) and Deeks' Funnel Plot Asymmetry Test were performed to evaluate the study quality and publication bias of included studies. Results: Nineteen studies were eligible for meta-analysis, comprising 1,089 patients with esophageal cancer who underwent 18F-FDG PET/CT before surgery. According to the content of the article, we divided the selected studies into per-patient basis group and per-nodal basis group (one of the articles was involved in both groups). For the per-nodal station basis group (12 studies, 5,681 stations), the pooled sensitivity and specificity estimates of 18F-FDG PET/CT for detecting regional lymph node metastasis were 66% [95% confidence interval (CI): 51-78%] and 96% (95% CI: 92-98%), respectively. The corresponding values on a per-patient basis group (8 studies; 506 patients) were 65% (95% CI: 49-78%) and 81% (95% CI: 69-89%) in sensitivity and specificity, respectively. Conclusions: Overall, 18F-FDG PET/CT have a moderate to low sensitivity and a high to moderate specificity for detection of regional nodal metastasis in esophageal cancer. Therefore, since the false rate is considerable, extending the extent of lymph node dissection or radiotherapy target volume is necessary after diagnosis of regional nodal metastasis by 18F-FDG PET/CT.
The study identified moped rider violation behavior leading to conflicts and crashes to help guide future countermeasure development. Mopeds (electric bicycles and light motorcycles) are a commonly used personal transportation mode in China, and moped crashes are increasing rapidly. This increase in crashes may be attributable to certain traffic behavior of moped riders. Video recordings were used to acquire data on moped riders' violation behavior and the violation behavior of bicycle, tricycle, and motorcycle riders at signalized intersections. One hundred twenty-five min of video were recorded from 10 intersections, and rider behavior was coded from 1,455 vehicles. Video data showed that moped riders committed more violations than did riders of bicycles, tricycles, and electric bicycles and that moped riders who engaged in violation behavior at intersections were involved in more frequent and more severe conflicts than were moped riders who did not engage in violation behavior. Typical moped violation behavior included running red lights, riding in improper directions, waiting at improper positions, riding in improper lanes, and overloading. Violation behavior was closely associated with the traffic environment (traffic facilities, traffic flow, traffic signal status, and other riders' behavior), but not with either the vehicle's characteristics or the rider's characteristics. This difference suggests that countermeasures related to the traffic environment would be more effective than those related to either vehicle or rider characteristics. Countermeasures within the areas of traffic regulation, traffic management, traffic facilities, vehicle management, and rider education are proposed.
Direct torque control (DTC) system is currently one of the favourable control schemes for ac motor drives since it has the important advantage that system performance is not dependent on the motor parameters except the stator resistance. However, if the stator resistance varies due to heating, the performance of the system will suffer if the stator resistance value used in calculating the stator flux does not match the actual one. The compensation for the effect of the variation of stator resistance then becomes necessary. This paper describes a fuzzy observer, which can estimate the stator resistance online, according to the actual stator current, motor speed and operation time. The fuzzy observer for stator resistance proposed in this paper is applicable not only in the DTC systems of induction and permanent magnet motors but also in other type of motor drive systems.
Mopeds, experiencing faster growth of use than bicycles, have been swarming urban streets in China in recent years. The mixture of mopeds and bicycles in the same road space has led to great change in the composition and the traffic flow characteristics of nonmotorized traffic. It is impractical to measure the nonmotorized traffic flow by simply aggregating the vehicle counts of mopeds and bicycles because of their distinct temporal–spatial traffic features. This paper proposes a methodology to measure the normalized volume of a nonmotorized traffic mix of mopeds and bicycles. A bicycle equivalent (BE) concept is introduced to measure the moped in equivalent bicycle units and then to normalize the traffic flow mix. Two BE analysis methods that express the relationship between speeds, densities, and occupied spaces for mopeds and bicycles have been developed. A case study estimates the BE from these methods by using field data collected at a midblock section of an arterial in Shanghai. Statistical analysis of observed data shows that the estimated equivalent unit of moped to bicycle is variable under different traffic conditions. Specifically, the equivalent value of moped to bicycle is less than one under lower-density conditions. The value is, however, more than one under higher-density conditions. These findings are valuable to support the measurement of a nonmotorized traffic mix of mopeds and bicycles.
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