中石化江苏成品油一次配送空间格局与优化

基于详实准确的政府及企业调研数据,以中石化江苏成品油一次配送为例,从配置效益和空间结构视角出发,借助运用地理网络分析和线性优化模型等方法,通过单位输油成本计算、优化情景构建计算和成品油配送格局比较分析,系统解析成品油一次配送空间格局与优化配置情况,从理论上尝试探讨其地理网络结构。研究发现:优化情境下的成本较2017年实际状况减少了30%左右,表明中石化江苏成品油一次配送效益不够优化;理论上,根据成品油"就近配置"原则,不同炼油企业各自在其优化情景区界内,配送单位输油成本较低的成品油;实际上,由于炼油企业的炼油能力差异、成品油输油通道不完善和分销中心油库设置差异等原因,不同炼油企业之间存在着相较优化情景区界或大或小的实际输油区界,且存在着某些分销中心油库同时接纳不同炼油企业成品油的现象,即存在混合输油区域。     

企业铁路运输开展“危险预知”活动模式的探讨

根据金川公司铁路运输企业安全工作实际,提出安全“危险预知”活动的概念,同时介绍了开展危险预知活动的方法、内容、效果,指出“危险预知”活动是企业实现安全预防为主,自主管理的很好模式。     

Analysis of maternal serum alpha-fetoprotein and free beta human chorionic gonadotrophin in the first trimester: Implications for down's syndrome screening

The aim of this study was to determine the maternal population, pregnancy, serum alpha-fetoprotein (AFP) and free β subunit of human chorionic gonadotrophin (FβhCG) parameters in a large series of women attending prenatal clinics before 15 weeks' gestation and to assess the practical problems of population screening for Down's syndrome in the first trimester using these markers. Serum samples were collected from 8600 women attending prenatal clinic booking visits. Maternal serum AFP and FβhCG medians were calculated for each day of gestation (49–104 days), using both dates and ultrasound estimates of gestation. The effects of maternal weight, twin pregnancies, and threatened abortion on AFP and FβhCG levels were analysed. The median age of the population was 27.1 years and the median weight 62.1 kg. Twenty-six per cent of samples were collected before 70 days and 50 per cent before 78 days' gestation. Eighty-nine per cent of all samples had gestational estimates by dates, 60 per cent by ultrasound and 52 per cent by both dates and ultrasound. The AFP median was 5 kU/1 at 49 days, 5.9 kU/1 at 70 days, and 17.9 kU/1 at 100 days. The peak median FβhCG level was 66.4 ng/ml at 64 days, falling to 20.6 ng/ml at 100 days' gestation. Both AFP and FβhCG levels showed log Gaussian distributions but the standard deviation for AFP was 20 per cent greater than that found in the second trimester. AFP and FβhCG levels showed an inverse relationship with maternal weight and were increased in twin pregnancies (1.68 and 1.97 multiples of the median, respectively). AFP and FβhCG can be readily measured in a large screening population in the first trimester. Down's syndrome screening protocols based on these markers could be refined by the use of gestations in individual days but AFP is likely to be a less effective marker and detection rates are likely to be lower than in the second trimester. To realize the potential of first-trimester screening, more women should be encouraged to attend the prenatal clinic in early pregnancy and ultrasound dating should be carried out for all pregnancies at this stage.     

“首次不罚制”在环境执法推行中的问题与建议

根据“首次不罚制”在环境执法中推行的初步实践，指出了该制度自身存在的问题和制度外的制约因素，并提出了克服这些瓶颈因素的建议。     

基于熵值法改进层次分析法马拉松急救能力评价模型的构建*

为减少马拉松赛事中猝死事故的发生,基于层次分析法、熵值法及模糊综合评价法,构建马拉松赛事医疗保障体系中现场急救能力的评价模型。通过分析马拉松赛事急救系统的组成及急救成功实例,总结影响马拉松急救能力的因素并建立评价指标体系;运用层次分析法确定评价体系的初始指标权重,熵值法修正指标权重,结合模糊决策参数法建立马拉松现场急救能力评价模型,并应用于2004年和2017年北京马拉松赛事,得到2004年北京马拉松的急救能力为“较差”,2017年北京马拉松的急救能力为“较好”,符合实际情况。结果表明:评价模型可为大型马拉松赛事的急救能力评价提供参考,为预防和减少马拉松赛事中猝死事件的发生提供技术支撑。     

北江万古流

北江是珠江水系第二大支流，全长582km，流域面积有4.7×105km2。北江是晚第三纪以来形成发育的，塑造了著名的丹霞地貌峡谷。水力、矿产、动植物和旅游资源丰富。