Objective Our objective is to build a model that explains the association between the exposure to trace elements in the soil and the risk of neural tube defects. Methods We built a function with different parameters t...Objective Our objective is to build a model that explains the association between the exposure to trace elements in the soil and the risk of neural tube defects. Methods We built a function with different parameters to describe the effects of trace elements on neural tube defects. The association between neural tube defects and trace element levels was transformed into an optimization problem using the maximum likelihood method. Results Tin, lead, nickel, iron, copper, and aluminum had typical layered effects （dosage effects） on the prevalence of neural tube defects. Arsenic, selenium, zinc, strontium, and vanadium had no effect, and molybdenum had one threshold value that affected the prevalence of birth defects. Conclusion As an exploratory research work, our model can be used to determine the direction of the effect of the trace element content of cultivated soil on the risk of neural tube defects, which shows the clues by the dosage effect of their toxicological characteristics. Based on our findings, future biogeochemical research should focus on the direct effects of trace elements on human health.展开更多
Estimation for weather-related failure probability of overhead transmission lines is essential in the reliability assessment of a power system.This paper analyzes the outage and weather data of 110 kV overhead transmi...Estimation for weather-related failure probability of overhead transmission lines is essential in the reliability assessment of a power system.This paper analyzes the outage and weather data of 110 kV overhead transmission lines in the Guangxi Zhuang Autonomous Region of China during 2011–2014.The result reveals obvious uneven distributions of outage events for time and space due to the spatial and temporal variation of severe weather.Based on the results, an estimation method is proposed in this paper.Split and aggregation is used to smooth the outage and weather data.The poisson model is adopted in our method to investigate the statistic characteristics of transmission line outage events.Regression analysis is applied to obtain the correlation between the weather intensity and history failure rate.Furthermore the method proposed is validated against the empirical outage data.展开更多
基金supported by the National "973" project on Population and Health (No. 2007CB5119001)the National Yang‐Zi Scholar Program, 211 and 985 projects of Peking University (No. 20020903)
文摘Objective Our objective is to build a model that explains the association between the exposure to trace elements in the soil and the risk of neural tube defects. Methods We built a function with different parameters to describe the effects of trace elements on neural tube defects. The association between neural tube defects and trace element levels was transformed into an optimization problem using the maximum likelihood method. Results Tin, lead, nickel, iron, copper, and aluminum had typical layered effects （dosage effects） on the prevalence of neural tube defects. Arsenic, selenium, zinc, strontium, and vanadium had no effect, and molybdenum had one threshold value that affected the prevalence of birth defects. Conclusion As an exploratory research work, our model can be used to determine the direction of the effect of the trace element content of cultivated soil on the risk of neural tube defects, which shows the clues by the dosage effect of their toxicological characteristics. Based on our findings, future biogeochemical research should focus on the direct effects of trace elements on human health.
基金supported by National NaturalScience Foundation of China (No.51307125)
文摘Estimation for weather-related failure probability of overhead transmission lines is essential in the reliability assessment of a power system.This paper analyzes the outage and weather data of 110 kV overhead transmission lines in the Guangxi Zhuang Autonomous Region of China during 2011–2014.The result reveals obvious uneven distributions of outage events for time and space due to the spatial and temporal variation of severe weather.Based on the results, an estimation method is proposed in this paper.Split and aggregation is used to smooth the outage and weather data.The poisson model is adopted in our method to investigate the statistic characteristics of transmission line outage events.Regression analysis is applied to obtain the correlation between the weather intensity and history failure rate.Furthermore the method proposed is validated against the empirical outage data.
