Objective: This study examined the time trends and age distribution patterns of estimated road traffic fatalities (RTFs) in China over the period 2002–2012. Methods: Data on age-, sex-, and region-specific RTF rates were provided by the Chinese Ministry of Health. The crude rates were standardized and the Mann-Kendall test was used to test the significance of time trends. Annual number of RTFs was calculated. To minimize the effect of yearly variations, magnitude of changes in and age distribution patterns of the RTFs were examined using mean values of 2 years. Results: RTFs increased significantly in China during the study period. Several features were identified for the RTFs in China. First, RTF rates skyrocketed in rural areas including towns and counties. Second, a significant increase in RTFs was also observed in cities even though the change in RTF rates was not statistically significant there. Third, individuals aged 20–24, 40–49, and 55–64, especially in rural areas, were particularly at risk for RTFs in recent years. Finally, RTFs became more common among middle-aged and older adults than young Chinese, with roughly 57% of all RTFs occurring among individuals aged 45 and above during 2011–2012. Conclusions: RTFs increased dramatically in China during the past decade, especially in rural areas. Age distribution patterns of RTFs have changed there. Community-based public health education and intervention programs are warranted. 相似文献
Objective: To reduce the severity of injuries and the number of cyclist deaths in traffic accidents, active safety devices providing cyclist detection are considered to be effective countermeasures. The features of car-to-bicycle collisions need to be known in detail to develop such safety devices.
Methods: The study investigated near-miss situations captured by drive recorders installed in passenger cars. Because similarities in the approach patterns between near-miss incidents and real-world fatal cyclist accidents in Japan were confirmed, we analyzed the 229 near-miss incident data via video capturing bicycles crossing the road in front of forward-moving cars. Using a video frame captured by a drive recorder, the time to collision (TTC) was calculated from the car's velocity and the distance between the car and bicycle at the moment when the bicycle initially appeared.
Results: The average TTC in the cases where bicycles emerged from behind obstructions was shorter than that in the cases where drivers had unobstructed views of the bicycles. In comparing the TTC of car-to-bicycle near-miss incidents to the previously obtained results of car-to-pedestrian near-miss incidents, it was determined that the average TTC in car-to-bicycle near-miss incidents was significantly longer than that in car-to-pedestrian near-miss incidents.
Conclusions: When considering the TTC in the test protocol of evaluation for safety performance of active safety devices, we propose individual TTCs for evaluation of cyclist and pedestrian detections, respectively. In the test protocols, the following 2 scenarios should be employed: bicycle emerging from behind an unobstructed view and bicycle emerging from behind obstructions. 相似文献
Millions of tons of waste activated sludge (WAS) produced from biological wastewater treatment processes cause severe adverse environmental consequences. A better understanding of WAS composition is thus very critical for sustainable sludge management. In this work, the occurrence and distribution of several fundamental sludge constituents were explored in WAS samples from nine full-scale wastewater treatment plants (WWTPs) of Beijing, China. Among all the components investigated, active heterotrophic biomass was dominant in the samples (up to 9478 mg/L), followed by endogenous residues (6736 mg/L), extracellular polymeric substances (2088 mg/L), and intracellular storage products (464 mg/L) among others. Moreover, significant differences (p < 0.05) were observed in composition profiles of sludge samples among the studied WWTPs. To identify the potential parameters affecting the variable fractions of sludge components, wastewater source as well as design and operational parameters of WWTPs were studied using statistical methods. The findings indicated that the component fraction of sewage sludge depends more on wastewater treatment alternatives than on wastewater characteristics among other parameters. A principal component analysis was conducted, which further indicated that there was a greater proportion of residual inert biomass in the sludge produced by the combined system of the conventional anaerobic/anoxic/oxic process and a membrane bioreactor. Additionally, a much longer solids retention time was also found to influence the sludge composition and induce an increase in both endogenous inert residues and extracellular polymeric substances in the sludge. 相似文献
该研究利用37℃培养的中温厌氧消化菌群为菌源,直接提温至50℃驯化培养,获得连续处理高浓度糖蜜废水的厌氧消化产甲烷菌群,并考察高温驯化过程中菌群结构及多样性的变化特征.结果表明,中温厌氧消化菌群直接转入高温培养后,在高浓度有机废水连续进料的条件下,厌氧消化过程能够快速启动生成甲烷,并在22 d后形成稳定的高温厌氧消化产甲烷菌群,平均甲烷生成效率为162.3 m L CH_4/g COD.乙酸和丙酸是厌氧发酵液内的2类主要有机酸,产气稳定期间的质量浓度分别为25.3和145.3 mg·L~(-1).转入高温培养后,菌群结构产生巨大变化,细菌变异程度强于古菌,并逐渐稳定成为以代谢糖、多种有机酸的细菌和产甲烷古菌为主要优势菌群的高温厌氧消化菌群.克隆结果显示细菌菌群以Thermacetogenium和Acetomicrobium faecal为主要优势菌群,分别占细菌克隆文库的33.44%和20.99%;古菌菌群以Methanosaeta和Methanoculleus为主要优势菌群,占古菌克隆文库的56.40%和39.75%.转入高温培养后,产甲烷古菌的总生物量下降,含量约为7.6×106拷贝/g活性污泥.研究结果对阐明温度选择压力对厌氧消化菌群结构与功能影响,改进高温厌氧消化菌群富集方法具有重要意义. 相似文献