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Electronic screens have become an integral part of modern life, accompanied with growing concerns for children's neuropsychological development. This study aimed to evaluate the associations between measures of early life screen exposure and hyperactive behaviors among preschool children. The study also aimed to investigate their cumulative effects and the critical window for these associations. A cross-sectional survey was conducted among 52 625 mother-child dyads at preschools in LongHua District of Shenzhen, China. A self-administered structured questionnaire was used to assess socio-demographic characteristics, duration of children's electronic screen exposure in each of the first 3 years following birth and the presence of current hyperactive behaviors. A series of logistic regression models were used to examine the relationship between previous screen time and current hyperactive behaviors. A crossover analysis was used to explore the critical window for a significant relationship between screen time and hyperactive behaviors. We found that exposure to electronic screens in the first 3 years of life was associated with hyperactive behaviors in preschool children. A cumulative effect was shown in children with an average daily screen time less than 60 min, with adjusted ORs increasing from 1.262 to 1.989 as screen exposure years increased from 1 to 3 years. A critical window was identified in that children in the first 2 years after birth were vulnerable to electronic screen exposure. Exposure to televisions, mobile phones, and computers were all related to elevated risks for hyperactive behaviors. In conclusion, early screen exposure appears to increase the risk for hyperactive behaviors in preschool children with the presence of a cumulative effect, a critical window and different electronic screens having similar effects. [ABSTRACT FROM AUTHOR]

A total of 69 soil samples and 80 Bassia dasyphylla (sandwort) leaf and stem samples from Gobi desert land in the Wuda coalfield, Inner Mongolia, were analyzed. The results show that the average fluorine content in the soil of the coalfield area, the periphery of the coalfield area, and the Wuda urban area was 1250, 757, and 552 µg/g, respectively, which is higher than the background value. This suggests that the coal seam fire burning there, leads directly to fluorine pollution within a limited area. The average fluorine content in the leaves and stems of Bassia dasyphylla sampled immediately around the sites of the ongoing coal fire was 532 and 388 µg/g, respectively, while the concentration in leaf and stem samples collected in areas remote from the fire, but within the field, was 146 and 107 µg/g, respectively. This implies that this historic coal fire, which has been burning for the past 50 years, is responsible for a general deposition of fluorine in the local area. This result suggests that coal seam fires may also be a novel source of fluorine pollution in some urban areas. The scenario of urban areas being adjacent to coal seam fires is not limited to Wuda but is relatively common in northern China, and elsewhere. Whether or not there are other cities currently under the influence of coal seam fires merits further investigation. [ABSTRACT FROM AUTHOR]

Although the topography of tidal flats is important for understanding their evolution, the spatial and temporal sampling frequency of such data remains limited. The waterline method has the potential to retrieve past tidal flat topography by utilizing large archives of satellite images. This study performs a quantitative analysis of the relationship between the accuracy of tidal flat digital elevation models (DEMs) that are based on the waterline method and the factors that influence the DEMs. The three major conclusions of the study are as follows: (1) the coverage rate of the waterline points and the number of satellite images used to create the DEM are highly linearly correlated with the error of the resultant DEMs, and the former is more significant in indicating the accuracy of the resultant DEMs than the latter; (2) both the area and the slope of the tidal flats are linearly correlated with the error of the resultant DEMs; and (3) the availability analysis of the archived satellite images indicates that the waterline method can retrieve tidal flat terrains from the past forty years. The upper limit of the temporal resolution of the tidal flat DEM can be refined to within one year since 1993, to half a year since 2004 and to three months since 2009. [ABSTRACT FROM AUTHOR]