New estimates of down syndrome risks at chorionic villus sampling,amniocentesis, and livebirth in women of advanced maternal age from a uniquely defined population

Current measures of livebirth prevalence of Down syndrome are derived from data obtained up to 20 years ago, before the introduction of the prenatal diagnostic tests amniocentesis and chorionic villus sampling (CVS). For women aged 36–52 years, but who were not tested prenatally, we proposed to make a direct estimate of current livebirth prevalence of Down syndrome. We could also determine prevalence at the time of CVS and amniocentesis in women of the same age undergoing prenatal testing. Differences in these prevalences allow an estimation of the relative loss of Down syndrome during pregnancy. In Victoria, Australia, we identified 3041 women having CVS, 7504 having amniocentesis, and 13 139 having no test. Smoothed regression estimates of age-specific livebirth prevalence were found to be higher than in the early studies. The estimate of spontaneous loss was 17 per cent between the time of CVS and amniocentesis, and 18 per cent after the time of amniocentesis. The latter figure is lower than previous estimates and may be explained by a greater likelihood of a Down syndrome fetus surviving to be liveborn, given the modern approach to early obstetric intervention. These current risk estimates of livebirth may be useful updates for genetic counselling, but perhaps more importantly, may be used as precise maternal age-related risk figures, necessary in the design and implementation of prenatal screening programmes for Down syndrome.     

二种除草剂遗传毒性的研究

以黄鳝为试验材料,研究了艾割和使它隆二种除草剂对鱼类的致突变性。对经腹腔注射染毒上述二种除草剂的受试黄鳝,通过对其活体肾细胞染色体数目和形态的观察,分析其突变率。研究结果(经t检验)显示:艾割和使它隆二种除草剂分别在其试验最低受试剂量50mg/kg和8.0mg/kg即可引起黄鳝的染色体畸变。采用SOS/Umu显色试验研究,在SOS/Umu试验中,使它隆和艾割2个受试除草剂可以诱发SOS阳性反应,且呈明显的剂量-效应关系。试验表明这二种除草剂具有遗传毒性,应对这二种除草剂严加管控,避免其对环境的影响。     

Cleaner production for continuous digester processes based on hybrid Pareto genetic algorithm

ＩｎｔｒｏｄｕｃｔｉｏｎＷｉｔｈｏｂｓｏｌｅｔｅｔｅｃｈｎｏｌｏｇｙ ,ｅｑｕｉｐｍｅｎｔ,ａｎｄｍａｎａｇｅｍｅｎｔ,Ｃｈｉｎａ′ｓｐｕｌｐａｎｄｐａｐｅｒｉｎｄｕｓｔｒｙｉｓｒｅｃｏｇｎｉｚｅｄａｓｂｅｉｎｇｏｎｅｏｆｔｈｅｍｏｓｔｈｉｇｈｌｙｐｏｌｌｕｔｉｎｇｓｅｃｔｏｒｓ.Ｉｔｓｐｌａｎｔｓｄｉｓｃｈａｒｇｅｄｏｖｅｒ3ｍｉｌｌｉｏｎｔ ａｏｆＣＯＤｉｎ 1 995,ａｃｃｏｕｎｔｉｎｇｆｏｒ 41 .8%ｏｆｔｈｅｏｖｅｒａｌｌｉｎｄｕｓｔｒｙｐｏｌｌｕｔｉｏｎｌｏａｄｏｆＣｈｉｎａ(Ｒｅｎ ,1 998) .Ｉｎｔ…     

环厦门海域水色变化的多光谱多时相遥感分析

采用基于影像光谱信息建立的水质遥感模型对环厦门海域1989～2003年间的水色变化进行了分析.通过对水体及其所含物质的物理光学性质分析,水质遥感模型的建立可以不依赖于和卫星同步的水质采样数据建立水质遥感.这使得遥感对水色分析的应用更容易,而且还可以利用大量卫星存档数据来进行水质的历史变化分析.使用基于可见光和近红外波段反射率创建的模型研究了离水信号和水中物质(悬浮物和浮游植物)的关系.提出了一套可用于Landsat TM/ETM 和SPOT 5影像的水专题处理流程,并用于揭示所研究海域中悬浮物和叶绿素浓度的时空变化规律.研究表明,利用基于影像光谱的水质遥感模型,可以快速有效地揭示长时间范围内水色的时空变化.总的看来,环厦门海域的悬浮物浓度在所研究的时期内,有显著的增加,叶绿素的浓度在局部也有明显的升高.最明显的是,高悬浮物浓度的海域面积所占的比例从1989年的0.2%上升到2003年的10.2%.综合分析表明,九龙江河口所带来的巨量悬浮物是该海域最主要的陆源排海物和污染源,过度的水产养殖是另一个主要的污染因子.     

遗传双线性模型在海洋冰情预测中的应用

提出了一套建立双线性模型（ＢＭ）的简便方案。用作者研制的加速遗传算法可同时估计ＢＭ模型各参数,成功地解决了ＢＭ建模这一难题,为ＢＭ模型的广泛应用提供了强有力的工具。实例的计算结果说明,这套方法在海洋冰情预测中是可行而有效的,通过利用预测过程中产生的残差信息进行反馈矫正,保证了ＢＭ模型高的拟合粗度和稳健的预测性能,增强了ＢＭ对复杂非线性动态系统的适应性。该方案具有一般性,在各种非线性时序动态预测中具     

遗传梯度法在水质数学模型参数估值的应用

介绍一种混合遗传算法－－遗传梯度法，并将其应用于水质数学模型参数估值，较一般优化算法能稳定得到的全局最优解。     

Modelling dynamics of managed tropical rainforests—An aggregated approach

The overuse of rainforests in the last century and its consequences necessitate a rethinking of logging policies. To this end models have been developed to simulate rainforest dynamics and to allow optional management strategies to be evaluated. Parameterisation of presently existing models for a certain site needs a lot of work, thus the parameterisation effort is too high to apply the models to a wide range of rainforests. Hence, in this paper we introduce the simplified model FORREG using the knowledge we have gained from a more complex model, FORMIX3-Q.     

遗传资源经济价值评价研究

初步建立了比较完整的遗传资源经济价值评估的框架、体系、平台 ,初步评估了人体基因、野生大豆、BT转基因棉的经济价值 ,为遗传资源市场化和国际遗传资源惠益分享提供科学依据 ,为进一步研究提供参考。