Genetic diagnosis by chorionic villus sampling before 8 gestational weeks: Efficiency,reliability, and risks on 317 completed pregnancies

Transabdominal chorionic villus sampling (TA-CVS) was attempted in 328 high-risk pregnancies at 6–7 weeks of gestation. Sampling was feasible in 97.7 per cent of cases; chorionic tissue specimens of more than 10 mg were obtained in 94.4 per cent ofcases at the first needle insertion and in 100 per cent after a second attempt. Fetal karyotyping succeeded in 99.4 per cent of cases, while no diagnostic failures were reported in enzymatic and DNA analyses. Fetal loss rate in the first 4 weeks after CVS was significantly higher than in the later CVS series (7.2 vs. 2.5 per cent), but 50 per cent of losses were observed within 2 weeks in cases of inviable aneuploidies. A high incidence of severe limb abnormalities (1.6 per cent) was detected in pregnancies intended to continue, confirming the aetiological role of early CVS. Unclear visualization of the placental limits and poor control of the needle path are thought to be the main reasons for the vascular disruption of the chorionic plate, and thereby hypoxic embryo tissue damage. A better selection of cases, together with high-resolution vaginal ultrasound visualization, and analytical techniques requiring a minimal amount of tissue should avoid any teratogenic effect of early CVS.     

Uterine cavity lavage: Adding fish to conventional cytogenetics for embryonic sexing and diagnosing common chromosomal aberrations

This study was undertaken to examine the efficacy for early prenatal diagnosis of uterine cavity lavage at the level of the internal os and to assess the rate of maternal contamination. In phase I, uterine cavity lavage was performed in 38 women scheduled for pregnancy termination between 6 and 12 weeks. In addition to short- and long-term cultures, one-colour FISH (fluorescence in situ hybridization) with Y and X probes was used for fetal sexing. Two-colour FISH was used in all known male fetuses for the assessment of maternal contamination. In phase II, lavage was performed on 16 women. Fetal sex was diagnosed with direct labelled X and Y probes and common numerical chromosomal aberration was attempted with 18 and 21 direct labelled probes. Fetal sexing was successful in all cases in phases I and II. Out of 34 patients in which tissue was obtained, only FISH was done in six. Long-term cell cultures were successful in the other 28 cases, but complete karyotyping in 19 (56 per cent). No chromosomal aberration was found with the direct labelled probes 18 and 21 in FISH. Maternal contamination was assessed to be 5–10 per cent. This simple and easy-to-master technique is very effective in obtaining fetal cells early in pregnancy for genetic diagnosis, especially by FISH. However, the safety of the procedure must be tested in ongoing pregnancies.     

Risk assessment of amniocentesis between 11 and 15 weeks: Comparison to later amniocentesis controls

We studied 693 consecutive early amniocenteses (prior to 15 weeks) and found a spontaneous abortion rate to 28 weeks' gestation of 1·5 per cent. A control group of women having standard amniocentesis (15–20 weeks) experienced a 0·6 per cent fetal loss in the same period. There were no other apparent differences between the two groups. Early amniocentesis results are generally available 4–6 weeks before standard amniocentesis and 1–3 weeks after chorionic villus sampling (CVS). Alpha-fetoprotein (AFP) can be accurately assayed in 11- to 15-week amniotic fluid samples but additional studies are necessary to determine the accuracy of neural tube defect (NTD) detection. Including the present study, over 5800 early amniocenteses have been reported and the results suggest that this is a relatively safe prenatal diagnostic test and an alternative to CVS and later amniocentesis.     

民国初年灾荒史研究综述

自民国迄今,一些政治家、思想家及学者分别从自然科学角度和社会历史角度对民国初年灾荒史予以诠释,依时间而言主要集中于20世纪80年代以后,依内容而言又呈现出一种多元化的态势。其间,虽然取得了一定的成就,诸如积累了一些资料、研究内容多样化等,但仍存在着一些不足。     

基于可拓云模型的区域生态安全预警模型及应用——以祁连山冰川与水源涵养生态功能区张掖段为例

针对区域生态安全预警中的不确定性问题,考虑生态安全等级边界信息的随机性、模糊性及动态性,利用可拓学中兼具定性和定量分析及动态性的物元理论和具有不确定推理特性的云模型,提出了基于可拓云模型的区域生态安全预警模型;运用该模型对祁连山冰川与水源涵养生态功能区张掖段2005—2015年生态安全进行了定量评估,并对2017年生态安全环境进行动态预警。结果表明:祁连山生态功能区张掖段2005—2015年的生态安全整体水平均处于"理想"以下,其变化趋势为"较差"到"一般"再到"良好";2017年祁连山冰川与水源涵养生态功能区张掖段生态安全为"蓝色"预警,但有向"黄色"转变的趋势,其中工业三废、环保投入强度、森林覆盖率及人均水资源量是影响祁连山冰川与水源涵养生态功能区张掖段生态安全的主要因素。     

基于BP神经网络和SVR的Fund?o尾矿坝排水数据预测对比研究

针对尾矿库运行过程中安全预警问题,选取2015年巴西Samarco铁矿溃坝事故案例,研究BP神经网络和SVR方法在排水数据预测的适用性。综合分析了排水数据的复杂且非线性的特点,以库水位、降雨量和干滩长度为输入特征,采用上述2个模型对尾矿坝排水数据进行预测。研究结果表明:基于BP神经网络预测结果的最大相对误差不高于4.35%;基于SVR算法的最大相对误差不高于9.21%;Fundo坝的排水预测结果是可行的,BP神经网络的预测精度更高,而SVR模型的运算速度更快。研究结果可为矿山安全工作的快速响应和溃坝预警提供信息支撑和参考依据。     

三峡库区水环境风险评估与预警平台总体设计与应用

为保障三峡库区水环境安全,提高环保部门的环境预警和应急科学处置能力,根据“平战结合”的平台建设思路,提出了基于面向服务(SOA)可扩展的架构、Webservice数据服务调用模式和模块化功能的平台构建技术,集成了地方环保业务系统的成果,设计和实施了一个体系、一张网、一张图、一张表、一个流程的“五个一”平台工程,研发了集污染源风险识别、环境预警监控、模拟预测、应急评估处置和信息发布5项功能为一体的三峡水环境风险评估与预警平台,并在重庆市环保部门实现了业务化运行应用. 平台研究成果可支撑应急管理和日常管理,并在一系列突发性事件中得到业务应用验证和应用,环境应急响应时间从1~2 h缩短至10~20 min,应急处置时间从原来的1~2 d缩短至1~2 h,显著提高了三峡库区水环境风险评估、预警和防范能力.      

Beyond performance and protocols: early responders' experiences of multiple accountability demands in the response to the 2015 Nepal earthquake

Critics have long questioned the push for professionalised and performance‐driven accountability in the humanitarian sector, yet the matter is largely treated as a ‘back office’ issue of standards, guidelines, and processes. Scant attention is paid to the accountability demands experienced by early responders to disasters. Set in the contested climate of the emergency response to the earthquake in Nepal on 25 April 2015, and drawing on interviews with 15 early responders, this paper reveals three forms of accountability demands: (i) accountability as compliance; (ii) accountability as the object of government regulation; and (iii) accountability as public opposition and interrogation. Beyond the performance‐centric, non‐governmental organisation‐driven understanding of accountability, early responders to the earthquake experienced multidirectional accountability demands, not only from donors and beneficiaries, but also from the national government and wider public. Engaging with public criticism is a significant feature of early responders' responsibility that warrants further consideration by the humanitarian community.     

贵阳市环境空气质量预报预警系统建立的探讨

分析了贵阳市空气质量预报中污染物、地形及下垫面、植被等关键影响因素。提出了贵阳市环境空气质量预报预警系统的整体架构,分别对排放源监测与管理系统、环境空气质量预报系统和污染预警与控制决策支持系统等三个核心部分进行阐述,进一步提出了贵阳市大气污染防控措施及防控机制。     

我国持久性有机污染物污染事故预警指标体系构建

面对严峻的持久性有机污染物(persistent organic pollutants,POPs)环境污染问题,以及不断提升的化学品风险管理要求,我国对于POPs污染事故预警管理的需求日益迫切.基于生命周期理论及POPs生成机制,针对不同的POPs和污染事故的种类,构建出POPs污染事故的预警指标体系,以期为完善我国POPs污染事故预警管理提供决策支持.预警指标体系主要包括两部分:POPs预警指标和运行保障机制.POPs预警指标包括了警源指标、警兆指标和警度指标.为保障预警体系的有效实施,构建了预警响应机制及政策保障机制,包括对风险源的动态清单管理和定期评估,及时有效的警情上报,各部门的协调合作等.