The prebiotic synthesis of pyrimidines in frozen solution

Most prebiotic syntheses depend on the reaction of concentrated precursor compounds to produce bio-organic molecules. It is now believed that the early Earth’s atmosphere was not reducing enough to have permitted copious synthesis of precursor molecules. Freezing allows reaction to occur even from dilute solution. This reaction has been demonstrated for the purines but not for the pyrimidines. It is shown here that dilute solutions of simple prebiotic molecules produce the biological pyrimidines cytosine and uracil upon freezing. Cold environments may have allowed synthesis of all of the RNA bases even from low organic yielding atmospheres, such as those of the early Earth, Mars, Titan and Europa.     

导弹用材料环境适应性数据库设计

目的 针对材料工艺师需要系统整合导弹环境适应性信息的手段、分析数据变化规律的工具、网络共享的平台,设计并开发导弹用材料环境适应性数据库。方法 数据库软件采用J2ee体系架构搭建,设计虚拟导弹数字化模型,通过建立大量的数据关联,将导弹基本结构信息、导弹整机失效信息、弹用材料基本性能信息、环境适应性信息和环境信息五大类信息整合为一体,供导弹模型调用。设计曲线绘制算法,采用ActionScript脚本语言编程,实现数据规律动态绘制,采用跨库关联建立数据关联查询和数据对比分析。结果 用户可通过鼠标操作,拆分和组装导弹模型,全方位观察导弹的构成。利用导弹模型整合的五大类环境适应性信息,直观反映导弹的构成和材料应用情况。软件能够查询导弹的故障模式、弹用材料环境适应性信息等,跨库关联则增强了的数据对比性。结论 该数据库已经通过软件测评并上线运行,为导弹多个型号的选材和防护设计工作提供帮助,用户反映良好。     

Determinant factors of corporate environmental information disclosure: an empirical study of Chinese listed companies

In order to help understand the environmental disclosure mechanism from the corporate perspective, this paper identifies the determinant factors affecting the disclosure level of corporate environmental information on the basis of stakeholder theory, and gives an empirical observation on Chinese listed companies. The corporate environmental information disclosure (EID) level appears to be marginal in current Chinese context. Nearly 40% of the sampled companies opened no substantial environmental data to the public as could be seen from the content analysis of disclosed information. The present condition is that the EID strategy of Chinese listed companies is oriented to fill up the government's environmental concerns. The corporate EID effort is significantly relative to its environmental sensitivity (a proxy of the pressure from the government) and its size. The role of other stakeholders, like shareholders and creditors tested in this study in effecting the EID, is found to be still weak. Another interesting finding is that the sampled companies are selectively opening their environmental information. Companies operating in eastern coastal regions, where the economy has been relatively developed, are more likely to disclose emission-related data. The better the company's economic performance, the more information on environmental investment and pollution control cost is disclosed. More concerns of the firm's stakeholders on environmental issues shall be promoted in order to encourage Chinese enterprises to disclose more environmental information and accordingly become more proactive for improving their environmental performance.     

餐饮源有机颗粒物排放特征

餐饮油烟是大气有机颗粒物的重要来源之一.本研究在深圳市内选择了西餐、茶餐厅、职工食堂和韩式料理这4种类型的餐馆,通过对这4类餐厅的外场采样,分析各类型餐厅油烟中有机颗粒物的化学组成,筛选了餐饮油烟污染源的有机特征组分.结果表明,各餐馆排放的PM_(2.5)中,有机物占60%以上.在所有定量的有机组分之中,脂肪酸含量最高,其次是二元羧酸和正构烷烃,而多环芳烃、甾醇和单糖等有机组分的含量较低.颗粒物的有机组成特征受到菜系的影响,西餐厅和韩式料理排放脂肪酸、正构烷烃和多环芳烃等有机物含量较高,但却排放了低含量的甾醇和单糖,茶餐厅和职工食堂则相反.餐饮源颗粒物中Fla/(Fla+Pyr)和LG/(Gal+Man)的比值受菜系影响较小,也区别于其他污染源的特征比值,可以作为餐饮源潜在的示踪物.餐饮源为深圳市大气颗粒物贡献了大量的脂肪酸和二元羧酸.     

大气颗粒物中水溶性有机物的研究进展

WSOC（水溶性有机物）广泛存在于云、雨水和大气颗粒物中,其可作为CCN（cloud condensation nuclei,云凝结核）影响大气热动力平衡、气候变化甚至危害人体健康.分析归纳了近年来国内外有关WSOC的研究,阐述了WSOC的来源、化学组成、理化性质、污染特征等,并总结了WSOC的单分子鉴定方法.结果表明:传统的分析检测方法,如GC-MS（gas chromatography-mass spectrometry,气相色谱质谱联用）、HPLC（high performance liquid chromatography,高效液相色谱）等,可以分析出部分低分子羧酸类和醇类,但不能检测出高分子、极性高的组分.新兴的分析检测方法,如HNMR（hydrogen nuclear magnetic resonance,氢核磁共振）,可以检测出WSOC中的官能团;IC（ion chromatography,离子色谱）可以较好、方便地检测出低碳有机酸类;HR-ToF-AMS（high resolution-time of flight-aerosol mass spectrometry,高分辨时间飞行气溶胶质谱）的分辨率较高,但由于其质谱谱图复杂,因此较难完整解析WSOC的结构信息;而FT-ICR-MS（Fourier transform ion cyclotron resonance,傅里叶变换离子回旋共振质谱法）可以与软电离结合,在尽可能获得更多分子离子峰的基础上,较多地解析出组分和结构信息;EEMs（excitation-emission-matrix spectra,三维荧光光谱）根据荧光分布和强度,可检测不同种类和来源的WSOC.据此,建议今后从以下几方面开展研究:①结合多种检测技术全面解析WSOC的组成和结构信息.②WSOC大气化学过程及形成机制的研究有待进一步深入.③WSOC的环境与健康效应.④不同种类、复杂的水溶性有机混合物的吸湿增长机制.      

单兵信息系统装备可靠性评估方法研究

首先介绍了士兵系统在环境适应性、信息安全、作战适应性、使用寿命等方面的需求,提出了一种可靠性设计方法,可有效解决单兵多模块信息系统可靠性评估问题,大幅提升士兵信息系统的设计效率。同时以典型士兵信息系统为例,进行了士兵结构可靠性、电气可靠性设计。     

信息约束条件下的流域农业面源污染控制优化

我国广大小流域迫切需要开展农业面源污染控制,但却面临着水质、水文、气象、土地等监测资料不足的信息约束条件。为了应对此问题,本文以具有冻融变化特征的东北地区为例,开发了一套信息约束条件下的流域农业面源污染控制优化系统。首先,提出了农业面源污染负荷的计算方法。其次,分析了流域水质的影响因素。接着,建立了面源污染输入与流域出水口水质之间的响应关系,经验证该系统输出数据与实际污染状况相吻合,能够很好地模拟流域污染状况。最后通过各种削减策略的运用,模拟出农业面源污染削减率和削减后的总氮浓度。通过采用本研究制定的控制优化方案,改变种植类型和面积以及改善施肥配施比,将污染源数据进行量化作为输入数据,经系统输出得到模拟污染输出数据,可得到较好的污染削减效果。研究结果为信息约束条件下治理流域农业面源污染提供了决策支持。     

长江生态环境保护修复智慧决策平台构建与初步设计

长江流域生态环境管理存在多部门“九龙治水”的现象,导致各类数据信息分散、科研成果碎片化,缺乏综合性信息查询与管理平台支持.针对长江生态环境保护工作对数据资源共享与精准决策的需求,提出构建长江生态环境保护修复智慧决策平台（简称“长江平台”）,按照基础层、数据汇集层、数据治理层、大脑层、应用层构建平台系统框架,设计数据采集处理、数据挖掘分析、基于WebGIS的数据展示、数据分级共享、调度会商、长江舆情发布、水环境模型工具、空间制图工具等主要功能,提出平台部署方案与分期建设方案,分析了平台建设面临的多元数据汇集与标准化处理、水质目标模型筛选、水环境预测预警功能开发等难点与关键技术,同时提出平台建设与运行保障机制.通过平台建设,可实现长江流域数据采集多样化、生态环境要素可视化、环境问题诊断精准化、管理响应自动化和决策会商便利化,为长江大保护提供智慧决策支持.      

Physicians' acceptability of termination of pregnancy after prenatal diagnosis in southern france

The acceptability of prenatal diagnosis for Down's syndrome has been extensively studied over the last 15 years but that of other pathologies remains largely unexplored. The main goals of this study were to approach physicians' opinions on six reasons for termination of pregnancy showing different deficiencies, i.e., Down's, Turner and Klinefelter syndromes, cystic fibrosis, spina bifida, and haemophilia, and to identify the origins of reserves. The influence of sociodemographic and professional characteristics of physicians on their opinions and attitudes during the consultation were studied. The data presented are based on information gathered in 1985 by a mailed questionnaire answered by 853 general practitioners, gynaecologists, obstetricians, and pediatricians in the Marseilles Genetic Centre's region. Stepwise logistic regression was used for the multivariate analysis. The results showed that 78 per cent of those answering favour termination of pregnancy for Down's syndrome and that only moral reticences were mentioned by the physicians opposed. Conversely, for haemophilia, only 21 per cent of the physicians considered this indication justified; those opposed were for the most part concerned that severity of illness did not justify termination of pregnancy. Overall, 33 per cent of physicians would voice their personal opinion on termination of pregnancy if so requested by consultees. Results on the influence of age and specialty evidenced their role on physicians' opinions. Indeed, 30 per cent of physicians opposed to pregnancy termination for one of the six fetal anomalies retained herein would modify their positions if diagnosis were possible in the first trimester of pregnancy.     

Building institutions based on information disclosure: lessons from GRI's sustainability reporting

Global Reporting Initiative (GRI) is the best-known framework for voluntary reporting of environmental and social performance by business worldwide. Using extensive empirical data, including interviews and documentary analysis, we examine GRI's organizational field and conclude that since its modest beginnings in 1999 GRI has been by several measures a successful institutionalization project. But the institutional logic of this new entity, as an instrument for corporate sustainability management, leaves out one of the central elements of the initial vision for GRI: as a mobilizing agent for many societal actors. This emergent logic reflects GRI's dominant constituency – large global companies and financial institutions and international business management consultancies – and not the less active civil society organizations and organized labor. We attribute these developments to factors such as building GRI within the existing institutional structures; the highly inclusive multistakeholder process; and the underdeveloped base of information users. From the institutional theory perspective, this case shows how the process of institutionalization is deeply affected by initial strategies of the founders, and how it reproduces existing power relations. From the governance perspective, this case leads us to question the power of commodified information to mobilize civil society and to strengthen governance based on partnerships.     

映秀湾水电站水质监测系统设计研究

基于映秀湾水电站河流水质情况,通过研究河流水质浊度及泥沙的海量数据,使用自动在线监测技术,对水质监测系统进行设计.采用自动化与信息化为一体的设计方式,分别对水质自动监测子系统与水质监测分析信息化子系统设计,实现水质浊度数据采集、传输、存储、监视、分析及决策功能,通过对数据实时监视、动态报警和发展趋势分析,为汛期水电站水轮机组及用水设施运行提供信息支撑,提升发电站机组发电运行效率,为泥沙含量较多的水电站提供实时在线监测技术服务.     

基于wavelet-SVM的PM10浓度时序数据预测

太原是以煤炭为主要能源的重工业城市,PM_(10)(particulate matter)是太原市的主要大气污染物,因此研究其变化趋势,并给出污染物浓度预测结果,为相关部门进行大气污染防治,为突发污染事件应急提供理论支持是一项非常重要的工作.支持向量机(support vector machine,SVM)应用于PM_(10)污染物浓度时序数据预测时,表现出良好的泛化能力.在预测模型建立过程中通常选择历史数据作为学习模型的输入特征,然而这样的数据表示形式,结构单一,信息表达不完备,在很大程度上将影响预测模型的泛化能力.本文以山西省太原市城区4个监测站点的PM_(10)日浓度数据为研究数据,通过小波变换(wavelet transform)将一维输入数据转化为由低频信息和高频信息构成的高维数据,并以该数据为输入数据建立wavelet-SVM预测模型.结果表明,相较于传统SVM模型预测,wavelet-SVM模型预测结果具有更高的精度,尤其能更加准确捕捉到PM_(10)浓度突变点,为大气污染预警提供有效信息支持,并且wavelet-SVM模型对于PM_(10)浓度时序数据变化趋势的预测精度有明显提升,能更好地预测PM_(10)浓度变化趋势,揭示PM_(10)浓度时序数据内在规律.     

派河及其支流溶解性有机质分子组成特征

溶解性有机质(DOM)是水生生态系统中的重要组成部分,派河作为"引江济淮"清水廊道工程江淮段的唯一输水通道,其DOM分子层面的组成信息和特性尚不明确.利用静电场轨道阱高分辨质谱技术对派河及其支流(光明大堰河)DOM分子进行表征,并且利用皮尔逊(Pearson)相关性分析和主成分分析(PCA)研究两条河流DOM的分子组成...     

基于水文地球化学信息和环境同位素的地下热水成因分析

以海南省乐东县福报地热田内分布的基岩热水井为研究对象,利用水文地球化学信息和环境同位素技术分析地下热水的形成机制。结果显示,本区地下热水以高偏硅酸、低矿化度为特征,水化类型为HCO_3-Ca型。氢氧同位素特征、Cl-SO_4-HCO_3及Na-K-Mg三线图表明,本区地下热水主要来源于大气降水,受地壳深部地热水影响较少。地下热水中~3H、~(14)C同位素年龄测定结果表明区域地下热水不存在大尺度的径流模型,且在出露过程中混入了常温水。     

Improved parameters for risk estimation in Down's syndrome screening

A new method is described for calculating maternal serum marker distribution parameters which will improve risk estimation when screening for Down's syndrome. The approach is to calculate parameters using data from the local screened population and data obtained by meta-analysis from all published studies. The local data are used to derive the variance and covariance in unaffected pregnancies. The meta-analysis is used for the mean level in Down's syndrome pregnancies together with the differences in variance and covariance between affected and unaffected pregnancies. Forty-four published studies were analysed. The mean level for Down's syndrome in multiples of the normal median was 0·73 for alpha-fetoprotein (AFP) in total of 1140 pregnancies, 0·73 for unconjugated oestriol (uE₃) in 613, 2·02 for human chorionic gonadotropin (hCG) in 850, and 2·30 for free β-hCG in 477. For all four markers, the variance in Down's syndrome was higher than in unaffected pregnancies; for AFP and uE₃, the covariances were also higher in Down's syndrome, but for the other markers they were lower. The method was illustrated using data from 6387 pregnancies screened in Leeds.     

中国省域碳排放强度的集聚效应和辐射效应研究

估算了中国1997—2013年30个省(市、自治区)的碳排放强度数据,并利用全局Moran's Ⅰ指数、局域Moran's Ⅰ指数以及莫兰散点图从集聚效应和辐射效应两个角度考察了我国区域碳排放强度空间分布特征.结果显示:1集聚效应:我国省域碳排放强度具有明显的空间集聚特征,碳排放强度水平相似区域倾向于相邻分布;另外,碳排放强度空间分布呈现不断优化的趋势,即"低-低"集聚不断增加,"高-高"集聚逐渐减少.2辐射效应:内蒙古、宁夏和山西等省对周边地区的碳排放强度具有明显的正向辐射效应,广东、福建和浙江等省对周边地区碳排放强度具有明显的负向辐射效应.最后,据此提出政策建议.     

A new water quality assessment model based on projection pursuit technique

A new water quality assessment model was built based on projection pursuit technique. A great quantity of sample data was applied to increase the model's precision. A new genetic algorithm combined with conditional optimization method was proposed and applied to the model optimization, which could deal with global optimization problem with various restrictions effectively. The case study shows that this model can give an appropriate assessment of water quality. Moreover, it can determine the index weights in an objective way or provide information for decision makers, which is difficult for other assessment methods.     

基于时间序列模型残差的中国东部地区空气质量指数（AQI）空间自相关特征分析

空间自相关分析可以揭示变量的空间聚集性质.基于中国东部城市群的日空气质量指数(AQI)数据,研究了AQI的空间自相关特征.同时,考虑到日AQI的空间非平稳性,分析分成两步进行.首先,对每个城市的日AQI序列建立时间序列模型,进而获得其标准残差序列;然后再基于残差项进行空间自相关分析,计算其全局Moran's I指数和局域Moran's I指数.结果表明,全局Moran's I指数体现出明显的季节变化特征,呈现出冬季高而夏季低的以年为周期的循环变化.通过分析局域Moran's I指数,发现中国东部城市群存在2个值得重视的高空间自相关区域:京津冀地区和长三角地区.由于残差项体现的是气象条件的影响,因此,大面积的高自相关区体现了邻近城市群空气质量对气象条件变化的同步响应特征.     

Genetic counselling and ethical issues with chromosome microarray analysis in prenatal testing

Molecular karyotyping using chromosome microarray analysis (CMA) detects more pathogenic chromosomal anomalies than classical karyotyping, making CMA likely to become a first tier test for prenatal diagnosis. Detecting copy number variants of uncertain clinical significance raises ethical considerations. We consider the risk of harm to a woman or her fetus following the detection of a copy number variant of uncertain significance, whether it is ethically justifiable to withhold any test result information from a woman, what constitutes an ‘informed choice’ when women are offered CMA in pregnancy and whether clinicians are morally responsible for ‘unnecessary’ termination of pregnancy. Although we are cognisant of the distress associated with uncertain prenatal results, we argue in favour of the autonomy of women and their right to information from genome-wide CMA in order to make informed choices about their pregnancies. We propose that information material to a woman's decision-making process, including uncertain information, should not be withheld, and that it would be paternalistic for clinicians to try to take responsibility for women's decisions to terminate pregnancies. Non-directive pre-test and post-test genetic counselling is central to the delivery of these ethical objectives. © 2012 John Wiley & Sons, Ltd.