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• Pedestrian crossing behavior at unsignalized midblock crosswalk was analyzed. • A Logistic model was developed to estimate the gap acceptance probability. • Six external factors were considered. • Gap size, crossing distance, waiting time and pedestrian location have significant effect. • Recommendations on improving crossing safety were proposed. Gap acceptance represents a pedestrian's assessment of how safe it may be to use an available gap in traffic flow at a particular point in time. Though walking is a major component of urban mobility, the high rate of fatal interaction with motor vehicle traffic raises safety issues around how pedestrians decide to accept the available gap. This paper explored these interactions by modeling gap acceptance behavior at the midblock crosswalks. Unlike other pedestrian gap acceptance studies that focus on individual psychological and sociological factors that are difficult to control or manage, this study focused on six environmental factors that we considered important and as having the potential to affect the pedestrians' gap acceptance decision at the crosswalks, i.e. gap size, crossing distance, number of waiting pedestrians, waiting time, vehicle traffic volume and position of pedestrian (whether on street kerb or median). Video data was collected on pedestrian gap acceptance from 13 midblock crosswalk locations in Shanghai, China. A Logit model with 96% accuracy was developed to describe and predict the pedestrian gap acceptance behaviors. The results show that gap size and crossing distance have the highest effect on the pedestrian gap acceptance decision. Pedestrians waiting at the kerbside could confidently accept gaps (with a 95% probability) when the gap is longer than 2.2s, 5.9s, and 9.6s under the condition that the crossing distance is 4 m (one lane), 7.5 m (two lanes), and 11 m (three lanes), respectively while pedestrians waiting at the median could confidently accept gaps when the gap is longer than 1.6s, 5.3s, and 8.5s respectively under the same conditions. The recommendations on improving the crossing safety are proposed accordingly. [ABSTRACT FROM AUTHOR]

Objective: To investigate the association between folate levels and the risk of gestational diabetes mellitus (GDM) risk during the whole pregnancy. Design: In this retrospective cohort study of pregnant women, serum folate levels were measured before 24 gestational weeks (GW). GDM was diagnosed between 24th and 28th GW based on the criteria of the International Association of Diabetes and Pregnancy Study Groups. General linear models were performed to examine the association of serum folate with plasma glucose (i.e. linear regressions) and risk of GDM (i.e. log-binomial regressions) after controlling for confounders. Restricted cubic spline regression was conducted to test the dosage–response relationship between serum folate and the risk of GDM. Setting: A sigle, urban hospital in Shanghai, China. Participants: A total of 42 478 women who received antenatal care from April 2013 to March 2017 were included. Results: Consistent positive associations were observed between serum folate and plasma glucose levels (fasting, 1-h, 2-h). The adjusted relative risks (RR) and 95 % CI of GDM across serum folate quartiles were 1·00 (reference), 1·15 (95 % CI (1·04, 1·26)), 1·40 (95 % CI (1·27, 1·54)) and 1·54 (95 % CI (1·40, 1·69)), respectively (P -for-trend < 0·001). The positive association between serum folate and GDM remained when stratified by vitamin B12 (adequate v. deficient groups) and the GW of serum folate measurement (≤13 GW v. >13 GWs) Conclusions: The findings of this study may provide important evidence for the public health and clinical guidelines of pregnancy folate supplementation in terms of GDM prevention. [ABSTRACT FROM AUTHOR]

Microbial respiration is considered to be one of the most sensitive factors in soil; however, it might be altered by soil pollution. To clarify the potential impact of low levels of total petroleum hydrocarbons (TPHs) on soil microbial respiration (SMR) in tidal wetland in Jiuduansha, Shanghai, the distribution and characteristics of TPHs in the typical zones of the Jiuduansha Wetland and nearby watershed were analyzed, and the relationship between soil microbial respiration and TPH was studied. The results showed that the average concentration of TPHs in the soil was 23.98 mg·kg−1, which was a relatively low pollution level. Moreover, the concentration of TPHs in the soil changed significantly with tidal elevation. The main petroleum pollutants in the soil were alkane and aromatic hydrocarbons with less than 10 carbons. The average concentration of TPHs of the surrounding watershed of Jiuduansha was about 0.26 mg·L−1, indicating that it was grade III seawater. The concentration of the inner watershed was higher than that of the outer watershed, indicating that Jiuduansha wetland could enrich TPHs to some extent. Based on the results of regression analysis and a pot experiment, there was a relationship between TPHs and soil microbial respiration. The input of TPHs from the surrounding watershed over long term periods might improve the SMR of the Jiuduansha tidal wetland. [ABSTRACT FROM PUBLISHER]