Detection and false-positive rates of maternal serum markers for Down syndrome screening according to maternal age in women over 35 years of age. A study of the agreement of eight dedicated software packages

Maternal serum markers for trisomy 21 screening (MSS) can be assayed in women ≥35 years in an attempt to reduce the need for invasive procedures and thereby avoid their side effects. Our objective was to compare, in women ≥35, eight different software packages dedicated to second trimester MSS, thus providing reliable data for patient counselling. A simulation study was carried out on 189 sera from women with Down syndrome fetuses and 11 962 sera from mothers of unaffected babies. The first step was to estimate the joint distribution of alpha-fetoprotein (AFP) and free beta-human chorionic gonadotrophin (β-hCG). The second step was to calculate trisomy 21 detection and false-positive rates for each software according to maternal age (35–45 years), using the usual 1:250 risk threshold. Agreement between software packages was measured using 2×2 kappa coefficients. Detection rates and false-positive rates increased with maternal age. Depending on the software, 57–71% detection rates were achieved at 35 years with 12–18% false-positive rates. At 45 years, 61–100% detection rates were achieved with 66–95% false-positive rates. Up to 39 years, all softwares were concordant (kappa coefficients >0.75). In the range 35–45 years, false-positive and detection rates increased substantially with maternal age and differences between software packages are observed. Copyright © 2002 John Wiley & Sons, Ltd.     

汽车涂装废水处理系统的优化

通过对重庆某汽车制造厂涂装车间原废水处理工艺运行状况的调查 ,分析出该废水处理运行中存在的主要问题是 :废水水量与水质很不稳定 ;相同的处理方法加大了对不同废水的处理难度 ;设备腐蚀较为严重。改造后的处理工艺 ,对不同的废水先进行不同的物化处理 ,然后进入SBR反应器进一步进行生化处理 ,并且在设备的预制时就采取了一系列的防腐措施 ,很好地解决了原处理工艺中存在的问题。     

基于响应面法的煤矿钻孔随钻超声成像仪器受力部件优化设计*

摘要:为研制适用于煤矿瓦斯抽采钻孔、满足施工强度要求的小尺寸随钻超声成像仪器，对随钻超声成像仪器的关键受力部位——超声探头安装孔进行优化设计，分析煤矿瓦斯抽采钻孔的一般规格，建立超声探头安装孔的三维模型，确定关键参数类型及其取值范围，采用极差分析法找到对受力部件强度影响较大的参数，基于响应面法开展有限元数值模拟，运用Box-Behnken设计方法得到超声探头安装孔关键参数与仪器受力部件性能指标的关系，优化受力部件关键参数的数值。结果表明:优化前最大的等效应力为138.6 MPa，优化后受力部件最大等效应力较优化前降低9.05%。结论验证了设计方法的有效性，为煤矿抽采钻孔随钻测井仪器的研制提供思路。     

Accounting for enforcement costs in the spatial allocation of marine zones

Marine fish stocks are in many cases extracted above sustainable levels, but they may be protected through restricted‐use zoning systems. The effectiveness of these systems typically depends on support from coastal fishing communities. High management costs including those of enforcement may, however, deter fishers from supporting marine management. We incorporated enforcement costs into a spatial optimization model that identified how conservation targets can be met while maximizing fishers’ revenue. Our model identified the optimal allocation of the study area among different zones: no‐take, territorial user rights for fisheries (TURFs), or open access. The analysis demonstrated that enforcing no‐take and TURF zones incurs a cost, but results in higher species abundance by preventing poaching and overfishing. We analyzed how different enforcement scenarios affected fishers’ revenue. Fisher revenue was approximately 50% higher when territorial user rights were enforced than when they were not. The model preferentially allocated area to the enforced‐TURF zone over other zones, demonstrating that the financial benefits of enforcement (derived from higher species abundance) exceeded the costs. These findings were robust to increases in enforcement costs but sensitive to changes in species’ market price. We also found that revenue under the existing zoning regime in the study area was 13–30% lower than under an optimal solution. Our results highlight the importance of accounting for both the benefits and costs of enforcement in marine conservation, particularly when incurred by fishers. Justificación de los Costos de Aplicación en la Asignación Espacial de Zonas Marinas     

Building robust conservation plans

Systematic conservation planning optimizes trade‐offs between biodiversity conservation and human activities by accounting for socioeconomic costs while aiming to achieve prescribed conservation objectives. However, the most cost‐efficient conservation plan can be very dissimilar to any other plan achieving the set of conservation objectives. This is problematic under conditions of implementation uncertainty (e.g., if all or part of the plan becomes unattainable). We determined through simulations of parallel implementation of conservation plans and habitat loss the conditions under which optimal plans have limited chances of implementation and where implementation attempts would fail to meet objectives. We then devised a new, flexible method for identifying conservation priorities and scheduling conservation actions. This method entails generating a number of alternative plans, calculating the similarity in site composition among all plans, and selecting the plan with the highest density of neighboring plans in similarity space. We compared our method with the classic method that maximizes cost efficiency with synthetic and real data sets. When implementation was uncertain—a common reality—our method provided higher likelihood of achieving conservation targets. We found that χ, a measure of the shortfall in objectives achieved by a conservation plan if the plan could not be implemented entirely, was the main factor determining the relative performance of a flexibility enhanced approach to conservation prioritization. Our findings should help planning authorities prioritize conservation efforts in the face of uncertainty about future condition and availability of sites.     

Optimizing conservation in species-specific agricultural landscapes

Recovery of grassland birds in agricultural landscapes is a global imperative. Agricultural landscapes are complex, and the value of resource patches may vary substantially among species. The spatial extent at which landscape features affect populations (i.e., scale of effect) may also differ among species. There is a need for regional-scale conservation planning that considers landscape-scale and species-specific responses of grassland birds to environmental change. We developed a spatially explicit approach to optimizing grassland conservation in the context of species-specific landscapes and prioritization of species recovery and applied it to a conservation program in Kentucky (USA). We used a hierarchical distance-sampling model with an embedded scale of effect predictor to estimate the relationship between landscape structure and abundance of eastern meadowlarks (Sturnella magna), field sparrows (Spizella pusilla), and northern bobwhites (Colinus virginianus). We used a novel spatially explicit optimization procedure rooted in multi-attribute utility theory to design alternative conservation strategies (e.g., prioritize only northern bobwhite recovery or assign equal weight to each species’ recovery). Eastern meadowlarks and field sparrows were more likely to respond to landscape-scale resource patch adjacencies than landscape-scale patch densities. Northern bobwhite responded to both landscape-scale resource patch adjacencies and densities and responded strongly to increased grassland density. Effects of landscape features on local abundance decreased as distance increased and had negligible influence at 0.8 km for eastern meadowlarks (0.7–1.2 km 95% Bayesian credibility intervals [BCI]), 2.5 km for field sparrows (1.5–5.8 km 95% BCI), and 8.4 km for bobwhite (6.4–26 km 95% BCI). Northern bobwhites were predicted to benefit greatly from future grassland conservation regardless of conservation priorities, but eastern meadowlark and field sparrow were not. Our results suggest similar species can respond differently to broad-scale conservation practices because of species-specific, distance-dependent relationships with landscape structure. Our framework is quantitative, conceptually simple, customizable, and predictive and can be used to optimize conservation in heterogeneous ecosystems while considering landscape-scale processes and explicit prioritization of species recovery.     

微生物除臭剂的筛选、复配及其除臭条件的优化

为了获取作为除臭微生物制剂的候选菌株,从垃圾渗滤液中分离筛选了4株具有对NH3和H2S高效降解菌株,分别标记为CC3、CC7、CC13和CC16.通过形态、生理生化和16S r DNA序列分析,分别鉴定为乳酸片球菌(Pediococcus acidilactici)、巨大芽孢杆菌(Bacillus megaterium)、嗜酸乳杆菌(Lactobacillus acidophilus)、粪产碱杆菌(Alcaligenes faecalis).菌株CC7、CC13和CC16组成的复配组合除臭效率最优,其复配比例为1∶1.5∶0.5,对NH3和H2S的去除率分别为83.56%和70.25%.通过单因素实验,确定微生物除臭剂最佳除臭条件:除臭时间为60 h,菌剂使用量为5%,除臭温度为30℃,初始培养基p H值为6.5.     

城市生活垃圾填埋处理甲烷排放估算及控制途径研究

随着人口的增长,城市化和经济化发展以及居民生活水平的不断提高,固体废弃物的排放量日益增多,废弃物处理不仅是大气中甲烷的一个重要排放源,而且已成为限制城市化进展和城市经济发展的重大问题之一。固体废弃物填埋处理甲烷的排放量的估算,对准确评估未来气候变化以及应对气候变化所带来的影响具有重要的意义。本文在分析了填埋场甲烷产生影响因素的基础上,估算了2005年-2010年杭州市填埋场甲烷排放量,提出了填埋场甲烷排放控制的对策建议,为杭州市温室气体减排工作提供参考意见。     

水资源规划优化技术研究进展及展望

文章针对水资源管理与规划的发展过程,详细论述了水资源系统管理与规划中常用优化技术的国内外研究成果及应用。根据是否考虑了模型参数或者模型结构的不确定性问题,将优化模型分为确定性优化模型和不确定性优化模型,同时对每种优化技术做了简要介绍,通过对不确定性优化模型的详细介绍指出了不确定性优化是当前水资源系统优化的热点;同时指出当前不确定性优化技术存在的问题,未来不确定性优化技术发展方向为多种不确定性以及多重效益的综合考虑等。     

针对PM2．5的武汉市大气监测点位的布局研究

武汉城市规模的扩大以及市内和周边的产业布局调整使得原有的大气监测网络不能准确反映城市大气污染现状,亟需进行布局优化。研究基于宏观视角,通过对武汉市自然条件、污染源分布和城市的发展规划进行综合分析,认为武汉市的大气污染以本地区的污染源影响为主;由于城市发展的“主城为核,多轴多心”空间结构,每个新城建成区应增设2-4个空气质量评价点,并按照人口比例作为权重纳入空气数据均值的计算;位于主城区的原有监测点基于PM2.5与原有监测项目有比较显著的相关性,可以继续使用。