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The coronavirus disease 2019 (COVID-19) pandemic has caused an unprecedented disruption to health care systems around the globe. Stroke is still an ongoing issue during the pandemic. We investigated the impact of the COVID-19 outbreak on emergent stroke care in Beijing, China. This is a retrospective analysis of two groups of patients with acute ischaemic stroke (AIS) registered in the Beijing Emergency Care Database between January 1, 2019, and December 31, 2020. Based on a database including 77 stroke centres, the quantity and quality of emergency care for stroke were compared. Subgroup analyses based on hospitals in different areas (high-risk and low/medium-risk areas) were carried out. A total of 6440 and 8699 admissions with suspected stroke were recorded in 2020 and 2019, respectively. There were no significant differences in the mean age and sex distribution for the patients between the two observational periods. The number of AIS admissions decreased by approximately 23.9% during the COVID-19 pandemic compared to that during the prepandemic period. The proportions of intravenous thrombolysis and endovascular treatment were 76.4% and 13.1%, respectively, in 2020, which were higher than those in 2019 (71.7% and 9.3%, respectively). There was no statistically significant difference in the time from stroke onset to arrival at the hospital (97.97 ± 23.09 min vs. 99.40 ± 20.76 min, p = 0.832) between the two periods. The door-to-needle time for thrombolysis (44.92 ± 9.20 min vs. 42.37 ± 9.06 min, p < 0.001) and door-to-thrombectomy time (138.56 ± 32.45 min vs. 120.55 ± 32.68 min, p < 0.001) were increased significantly in the pandemic period compared to those in the prepandemic period, especially in hospitals in high-risk areas. The decline in the number of patients with AIS and delay in treatment started after the launch of the level-1 public health emergency response and returned to stability after the release of professional protocols and consensus statements. Disruptions to medical services during the COVID-19 pandemic have substantially impacted AIS patients, with a clear drop in admission and a decline in the quality of emergent AIS care, especially in hospitals in high-risk areas and at the time of the initial outbreak of COVID-19. Health care systems need to maintain rapid adaptation to possible outbreaks of COVID-19 or similar crises in the future. [ABSTRACT FROM AUTHOR]

Surface water is a crucial resource and environmental element for human survival and ecosystem stability; therefore, accurate information on the distribution of surface water bodies is essential. Extracting this information on a large scale is commonly implemented using moderate- and low-resolution satellite images. However, the detection and analysis of more detailed surface water structures and small water bodies necessitate the use of very high-resolution (VHR) satellite images. The large-scale application of VHR images for water extraction requires convenient and accurate methods. In this paper, a method combining a pixel-level water index and image object detection is proposed. The method was tested using 2018/2019 multispectral 4-m resolution images obtained from the Chinese satellite Gaofen-2 across Beijing, China. Results show that the automatic extraction of water body information over large areas using the proposed method and VHR images is feasible. Kappa coefficient and overall accuracy of 0.96 and 99.8% after post-classification improvement were obtained for testing images inside the Beijing area. The Beijing water body dataset obtained included a total of 489.53 km2 of surface water in 2018/2019, 108.01 km2 of which were ponds with an area smaller than 2 km2. This study can be applied for water body extraction and mapping in other large regions and provides a reference for other methods for using VHR images to extract water body information on a large scale. [ABSTRACT FROM AUTHOR]

Nitrate (NO3−) is a major contributing species to haze formation in Northern China. So far, formation processes and source apportionments of nitrate aerosols during haze pollution have not yet been well understood. In this study, the PM2.5 samples were collected in Beijing from 13 November to 24 December 2018. In addition to water‐soluble ions, oxygen (δ18O‐NO3−) and nitrogen (δ15N‐NO3−) isotopes in particulate NO3− were also determined, in order to investigate the formation pathways and potential sources of NO3− aerosols. The results showed that NO3− was a dominant species (43%) of secondary inorganic aerosols during the sampling period. The δ18O‐NO3− and δ15N‐NO3− values averaged at 83.8 ± 13.4 and 11.5 ± 5.0‰, respectively. Combining isotope compositions and Bayesian isotope mixing model, we found that heterogeneous reaction and gas phase oxidation contributed equally to nitrate formation during the sampling period. However, the contribution of heterogeneous processes to nitrate increased from 39% during the clean period to 64% during the haze period. On average, coal combustion, biomass burning, vehicle emissions, and soil emission contributed 50%, 26%, 20%, and 4%, respectively, to nitrate aerosols during the sampling period. Compared to the result in 2013, the significant decrease (~21%) of relative contribution of coal combustion to nitrate was due to strict reduction of coal consumption in Beijing. Finally, the relative contribution of traffic emissions to nitrate increased from 18% during the clean period to 30% during the haze period, suggesting that control of traffic emissions would be an important way to decrease nitrate concentrations and improve the air quality in Beijing. Key Points: Nitrate aerosols in Beijing during the haze events were mainly produced by hydrolysis of N2O5 under high humidity conditionsThe contribution of coal combustion to atmospheric nitrate decreased significantly after clean air actions implemented by Chinese governmentStrict control of traffic emissions would be an important way to decrease nitrate concentrations and improve the air quality in Beijing [ABSTRACT FROM AUTHOR]

Abstract: With high speed of increasement in electrical and electronic products, the relevant wastes turn out to be serious in China. But a corresponding recycling system of WEEE has yet to be established. The actual WEEE flow in China is therefore kind of unknown. Through an in-depth analysis of the recycling system and extended survey of the WEEE recycling process in Beijing, this paper puts forward a WEEE closed loop chain model concerning the source, pathway and volume of the flow. It identified some key control points in the WEEE recycling process, which are taken into account in several policy recommendations. [Copyright &y& Elsevier]

Method of train traction calculation is applied into calculate station-end turn-back capacity of urban rail transit, and the calculation effects are analyzed. First of all, this paper described and analyzed categories and operation progress of station-end turn-back, and obtained the minimal departure interval calculation formula of single track turn-back and double track turn-back, and suggested the reasonable turn-back track number when the throat area cannot operate parallel. Then, the kinetic equation, which solved the calculation method of station-end turn-back by using train traction calculation, was proposed. Finally, this paper used Beijing subway station Beijingxi under construction and DKZ4 trains as an example, and obtained the minimal departure intervals of station-end turn-back while DKZ4 train was operated under energy-saving mode and time-saving mode: the turn-back time using double tracks is much longer than that using single track. Based on these, this paper compared and analyzed the calculation results with that using average acceleration and deceleration, and shows that using train traction calculation is valuable in the capacity calculation of turn-back station. [ABSTRACT FROM AUTHOR]

• Explore 3 recent policies which aim to equalize school access in Beijing, China. • Study causal effect on house prices using property transaction records. • Use MDID to allow for systemic differences between treatment and control group. • 4–8% price premium for eligibility to enrol in municipal-level key primary school. • Robust to alternative school prestige measures or excluding existing elite schools. We explore recent policy changes which aim to equalize access to elite elementary schools in Beijing in order to identify the effect of access to quality education on housing prices. Using property transaction records from Beijing over the period 2013–2016, we construct a balanced panel of residential complexes , each of which is linked to designated primary schools. Whereas the multi-school dicing policy involves randomly assigning previously ineligible pupils to key elementary schools through lotteries, the policy of school federation led by elite schools consolidates ordinary primary schools through alliances with elite schools. Moreover, a residential complex in an ordinary primary school catchment can be reassigned to a key elementary school catchment through a "pure" re-designation effect. We allow for systemic differences between the treated and non-treated residential complexes using the Matching Difference-in-Differences (MDID) approach. Our estimates indicate that the effect on house prices of being eligible to enrol in a municipal-level key primary school is about 4–8%, while the premium for being eligible for a less prestigious district-level key primary school is only about 2–3%. Our findings are robust to two alternative measures of primary school prestige: an unofficial ranking from a popular parenting support website; and the number of awards in academic tournaments. [ABSTRACT FROM AUTHOR]