Variations in the HCN/HNC abundance ratio in the Orion molecular cloud

We have used observations of the rare isotopes of HCN and HNC to determine the relative abundance of these two chemical isomers along the central ridge of the Orion molecular cloud. The abundance ratio [HCN]/[HNC] decreases by more than an order of magnitude from the relatively warm plateau and hot core sources toward the KL nebula to the colder, more quiescent clouds to the north and south. Even in the cooler regions, however, the ratio is an order of magnitude larger than that found in previous investigations of cold dark clouds. We determine the kinetic temperature in the regions we have studied from new observations of methylacetylene (CH3CCH), together with other recent estimates of the gas temperature near KL. The results suggest that the warmer portions of the cloud are dominated by different chemical pathways than those in the general interstellar cloud material.     

足尺磁流变阻尼器的建模及动态特性

在过去三十年左右的时间里,结构保护系统受到了广大研究者的普遍关注.这种保护系统可以用来降低自然灾害(如地震、强风)对上木工程建筑的损害.由于磁流变阻尼器机械结构简单,动态范围大,能耗低,回复力大,鲁棒性良好,能够在满足不同工程项目需求的同时提供有效的结构抗震抗风手段,目前它是一种非常有前途的半主动结构减震装置.本文首先介绍了磁流变液体和装置的主要特性和优点,建立了磁流变阻尼器的伪静力轴对称模型,并将其结果和平行板模型以及阻尼器实验结果进行了比较.尽管伪静力模型对于阻尼器的设计十分有效,但是它们还不足以描述阻尼器的动态特性.对实际工程应用来说,动态响应时间是一项非常重要的性能指标.文章还讨论了影响磁流变阻尼器动态响应时间的因素,建立了基于Bouc-Wen模型的阻尼器动态模型.同时文章也提出了优化阻尼器动态响应的途径和方法以及其实验验证.     

南非德兰士瓦层序早元古代古土壤和铁质岩中的层状金矿化

在玄武岩表面及上覆的海进沉积层序之底部发育的早元古代古土壤中含有黄铁矿,在某些情况下,这些黄铁矿含金.层状矿化延伸数百公里.虽说这种矿化可用几种成因模式加以解释,但作者得出了这样的结论:即金矿化发生在成壤作用和(或)成岩作用时期.人们认为,富含硫化物的地下水将金自玄武岩和古土壤B层中淋滤出来,随后因HS~-活动的减弱而沉淀.据信,金的沉淀是因大气氧化作用及与古土壤A层富铁淋滤液发生反应而造成的,早先存在的氧化铁矿物的黄铁矿化,亦对金的沉淀产生了影响.可以断定,成壤的金矿胎至少可对维特瓦特斯兰德型(Witwatesrand TyPe)矿床中金的成因作出某些解释.     

Tar ball frequency data and analytical results from a long-term beach monitoring program

Following the spill of fuel oils from the New Carissa in February 1999, approximately 300 km of beaches on the Pacific coast of North America were surveyed. A long-term observation program focused on the documentation of stranded tar balls in the vicinity of the spill site. Systematic beach surveys which were conducted over the period March 1999 to April 2001 and semi-logarithmic scale, time-series plots proved the most useful format for identifying trends. Beach monitoring continued through to August 2001. by which time 212 tar balls had been analyzed by GC/MS for their chemical characteristics. The samples of tar balls collected between February 1999 and August 2001 were qualitatively compared with New Carissa source oils (NCSO) and 101 (48%) were not consistent with NSCO. The presence of tar balls that are not related to an incident can confound attempts to define cleanup or endpoint criteria and to assess possible injury to natural resources.     

用于环境地质填图的组合遥感图像——在西班牙CdGN自然公园的应用

西班牙的Cabo de Gata Nijar天然公园提供了某些使其具有重要地质生态和环境意义的独特特征。作为该公园环境和采矿活动（直到十几年前才停下来）产生影响研究的优先步骤,确定了矿山和废物遗弃场地的位置,对岩性作了鉴定。为了达到这个目的,采用了不同的遥感技术来建立高分辨率的图像文件,图像文件将成为该区地质和环境填图的根据：因为从前的采矿活动牵涉到当地的环境,所以特别注意这些区域。由于具有不同空间／频谱分辨率的遥感图像日益加大的可用性,因此它们已成为很有用的工具。上述的是SPOT全色和陆地卫星专题成像仪多频图像的情形,它们是地质和环境研究中最常使用的基于遥感的两种图像。在为数众多阐述组合遥感图像资料的技术中,本文利用SPOT全色和陆地卫星TM资料研究那些基于亮度一色相一彰度（饱和度）、主要成分分析、高通滤波器和颜色正规化的变换。该研究的目标是：分析和对比一些最常使用的方法;选择最适合用于详细地质．环境研究的方法;将该方法用于Cabo de Gata Nijar地区一国家最具特色的一个天然公园场地。     

Data-driven Simulations of Magnetic Field Evolution in Active Region 11429:Magneto-frictional Method Using PENCIL CODE

Coronal magnetic fields evolve quasi-statically over long timescales and dynamically over short timescales.As of now there exist no regular measurements of coronal magnetic fields,and therefore generating the coronal magnetic field evolution using observations of the magnetic field at the photosphere is a fundamental requirement to understanding the origin of transient phenomena from solar active regions(ARs).Using the magneto-friction(MF)approach,we aim to simulate the coronal field evolution i...     

The Problem of the Lower Yangtze Terraces

INTRODUCTION During a journey taken to easternmost Hsikang during the summerof 1936,the author took the opportunity of examining the interestingterrace features of the lower Yangtze river(Fig.1).By travelling     

Overview of integrative tools and methods in assessing ecological integrity in estuarine and coastal systems worldwide

In recent years, several sets of legislation worldwide (Oceans Act in USA, Australia or Canada; Water Framework Directive or Marine Strategy in Europe, National Water Act in South Africa, etc.) have been developed in order to address ecological quality or integrity, within estuarine and coastal systems. Most such legislation seeks to define quality in an integrative way, by using several biological elements, together with physico-chemical and pollution elements. Such an approach allows assessment of ecological status at the ecosystem level ('ecosystem approach' or 'holistic approach' methodologies), rather than at species level (e.g. mussel biomonitoring or Mussel Watch) or just at chemical level (i.e. quality objectives) alone. Increasing attention has been paid to the development of tools for different physico-chemical or biological (phytoplankton, zooplankton, benthos, algae, phanerogams, fishes) elements of the ecosystems. However, few methodologies integrate all the elements into a single evaluation of a water body. The need for such integrative tools to assess ecosystem quality is very important, both from a scientific and stakeholder point of view. Politicians and managers need information from simple and pragmatic, but scientifically sound methodologies, in order to show to society the evolution of a zone (estuary, coastal area, etc.), taking into account human pressures or recovery processes. These approaches include: (i) multidisciplinarity, inherent in the teams involved in their implementation; (ii) integration of biotic and abiotic factors; (iii) accurate and validated methods in determining ecological integrity; and (iv) adequate indicators to follow the evolution of the monitored ecosystems. While some countries increasingly use the establishment of marine parks to conserve marine biodiversity and ecological integrity, there is awareness (e.g. in Australia) that conservation and management of marine ecosystems cannot be restricted to Marine Protected Areas but must include areas outside such reserves. This contribution reviews the current situation of integrative ecological assessment worldwide, by presenting several examples from each of the continents: Africa, Asia, Australia, Europe and North America.     

雅鲁藏布江缝合带的双陆内俯冲构造与部分熔融层特征──INDEPTH项目结果的初步综合

根据中、美两国合作开展的西藏深反射地震结果,提出雅鲁藏布江缝合带（YZS）的"双陆内俯冲"构造模式和缝合带南、北分别存在着不同特征的、规模不一的部分熔融层;提出YZS处断裂向深部延深有限,认为YZS处地壳增厚有4种机制：①地壳规模的大的俯冲增厚;②上部地壳内的俯冲和背冲增厚;③下地壳内的底部垫托增厚和挤压增厚;④深部熔融体的向上挤入而引起的地壳增厚.提出可能存在两条大的伸展性断裂,造成江孜南、北地块间出现了大升降.