作为决策支持工具的地理信息系统的演变

地理信息系统(GIS)界是由多种人组成的集体。林学家、地理学者、地方政府机关、公共服务部门和科学研究工作者都在探讨这同一领域,但方向有所不同。联系的纽带是他们都涉及到空间参照数据,即地球表面上具体地区的属性。     

STUDY ON BEIJING''''S EMERGING MOBILE COMMUNICATION INDUSTRIAL CLUSTER AND ITS POLICY IMPLICATIONS

1INTRODUCTIONClusters,definedasgeographicallyproximategroupsofinterconnectedcompaniesandassociatedinstitutionsinparticularfields,linkedbycommonalitiesandcomple-mentarities(PORTER,2000),havearousedanintenseinterestofurbanandregionalplanningresearchersandpolicymakersoverthepastdecades.Itiswidelyrecog-nizedthatclusterscanpromoteproductivityandinno-vation,developlocalcompetitiveadvantages.Popular-izedbyMichaelPORTERinhisbook“TheCompetitiveAdvantageofNationsin1990,theclusterisnotanewcon…     

11颗类星体光谱(英文)

对天区0112-35的UKST物端棱镜底片上的11个类星体候选者进行了光谱观测,证实为类星体,给出了它们的红移值、证认图及光谱图。11个类星体中有6个属于角距小于4角分的3对类星体;1个类星体-星系对。     

Measurement of stress effects (scope for growth) and contaminant levels in mussels (Mytilus edulis) collected from the Irish Sea

The objective of this research was to quantify the impact of pollution along the coastlines of the Irish Sea. Pollution assessment was based on the combined measurement of scope for growth (SFG), and chemical contaminants in the tissues of mussels (Mytilus edulis) collected from 38 coastal sites around the Irish Sea during June-July in 1996 and 1997. On the UK mainland coast, the SFG showed a general trend with a significant decline in water quality in the Liverpool and Morecambe Bay region. High water quality was recorded along the west coast of Wales, as well as southwest England and northwest Scotland (clean reference sites outside the Irish Sea). Along the coast of Ireland there was a similar trend with reduced SFG within the Irish Sea region. SFG was generally low north of Duncannon and then improved north of Belfast. The poor water quality on both sides of the Irish Sea is consistent with the prevailing hydrodynamics and the spatial distribution of contaminants associated with urban/ industrial development. The decline in SFG of mussels on both sides of the Irish Sea was associated with a general increase in contaminant levels in the mussels. Certain contaminants, including PAHs, TBT, sigmaDDT, Dieldrin, gamma-HCH, PCBs, and a few of the metals (Cd, Se, Ag, Pb), showed elevated concentrations. Many of these contaminants were particularly elevated in the coastal margins of Liverpool Bay, Morecambe Bay and Dublin Bay. A quantitative toxicological interpretation (QTI) of the combined tissue residue chemistry and SFG measurements indicated that at the majority of coastal sites, c. 50 to > 80% of the observed decline in SFG was due to PAHs as a result of fossil fuel combustion and oil spills. TBT levels were highest at major ports and harbours, but these concentrations only made a minor contribution to the overall reduction in SFG. At no sites were individual metals accumulated to concentrations that could cause a significant effect on SFG. The study identified many sites where the observed reduction in SFG was far greater than predicted from the limited number of chemical contaminants analysed, thus indicating the presence of additional 'unknown toxicants'. Sewage (containing domestic, agricultural and industrial components) appears to be an important contributor to reduced SFG and linear alkylbenzenes (LABs) and As may provide suitable 'sewage markers'. There was a highly significant positive correlation between SFG and As (P < 0.001). This relationship may be due to reduced As uptake by algal food material and mussels at sites with elevated P04 concentrations (e.g. at sites with sewage inputs). Phosphate is a known competitive inhibitor of As accumulation, at least in algae. The results highlight that further research is required on 'sewage markers' in mussels. The SFG approach therefore provides a rapid, cost-effective and quantitative measure of pollution impact, as well as a means of identifying the causes through a QTI of tissue contaminants levels. It also serves to identify the presence of unidentified toxicants and areas that require further study.     

Remittances and migration--the commerce of movement

"This paper comments upon the role of remittances in a variety of emigrant situations, traces the way remittance patterns change over time and evaluates the importance of remittance payments for personal and national economies. It considers the concept of 'remittance-societies" in the South Pacific and elsewhere, and briefly examines the various mechanisms involved in the emigration-remittance cycle, including the expectation of interactions and interdependence that exists between migrants and their home-based kin, and the sacrifices and hardships often endured by many migrants to meet obligations back home."     

Permeable Reactive Barrier for the treatment of contaminated surface water in Katedan industrial development area, Hyderabad, India

Permeable Reactive Barrier （PRB） is an emplacement of inert material （s） in the subsurface, designed to intercept a contaminated plume, provides a preferential flow path through the reactive media, and transforms the contaminant into environmentally acceptable forms to attain concentration remediation goals at the discharge of the barrier. The phenomena, which help in remediation within PRB, are adsorption/sorption, precipitation, oxidation/reduction and biodegradation. Various materials like zero-valent iron, zero-valent bi-metals, natural zeolites, organic carbon, fly ash, zeolites, limestone, activated alumina, apatites, etc. have been tried by many researchers to remove organic and inorganic contaminants. In USA, Canada, and many European countries commercial full-scale and pilot scale PRBs are successfully working. The design and installation of full scale PRBs needs laboratory treatability and dynamic flow column experiments？ The concept of PRB is being applied to treat contaminated surface water in the Katedan industrial area, Hyderabad, India. National Geophysical Research Institute （NGRI）, Hyderabad, India, conducted systematic studies in collaboration with Norwegian Geotechnical Institute （NGI）, Norway, to develop PRB technique to decontaminate the surface water pollution due to industrial effluent. A site assessment study in the Katedan Industrial Area, were carried out and water, soil and sediment from the lakes of the area were found to be polluted with high concentrations of heavy metals like As, Pb, Cr, Cd, Ni, etc. Adsorption studies at NGRI with synthetic samples and in-situ industrial effluent using different reactive media for removing contaminants like arsenic, chromium, cadmium, copper, nickel, lead and zinc have been carried out and yielded satisfactory results. The performance of zero-valent iron and limestone is encouraging in removing As,     

~(210)Pb chronology and trace metal geochemistry at Los Tuxtlas, Mexico, as evidenced by a sedimentary record from the Lago Verde crater lake

Lago Verde is a fresh water maar found in the San Martin volcano, at the Sierra of Los Tuxtlas, Mexico, currently the northernmost remnant of the tropical rain forest in America. A sediment core from Lago Verde was analyzed for 210Pb and 137Cs in order to…     

新西兰阿瑟山口地震之谜2.余震分布及其与区域应力场和诱发应力场的关系

1994年M_W=6.7的阿瑟山口地震的余震分布对于逆冲断层事件是不寻常的,其实际断层面沿NNW方向扩展了12 km,SSE方向扩展了30 km,走向为NE-SW。我们运用几种方法反推此区域的应力场,其中包括大地测量结果、地震震源机制结果,并用P波偏振数据反演了应力张量的方向。反演方法是新的,并不需要所用事件的震源机制,方法中也考虑了库仑破裂准则。所有结果均表明应力场支持走滑断层而不是逆断层。应力场中几乎水平的σ_1和σ_3主轴走向分别为298°和28°。运用位错理论,我们计算了阿瑟山口地震及其最大余震(走滑事件)诱发的应力并叠加到区域应力场中。远离主震断层面的余震位置与最优取向断层面上诱发的库仑破裂应力高值区域有很好的对应关系。然而,有一些高诱发库仑破裂应力的区域缺乏余震。与其他地方的观测一样,倾斜(19°)板块收敛区域的地震滑动可以分解为平行和垂直于板块边界的分量。像发生在太平洋板块和澳大利亚板块边界的右旋阿尔卑斯断层上那样,大部分滑动是平行的。然而,像阿瑟山口地震那样的偶尔的逆断层事件至少可以解释滑动的某些垂直分量和南阿尔卑斯隆起的形成。     

SOIL CONSERVATION EFFICIENCY OF DIFFERENT MODELS CONVERTING FROM STEEP FARMING SLOPE PLOTS IN YA''''AN, SICHUAN, CHINA

Converting farming slope land into artificial forestland or grassland is a major measure of soil/water conservation. Five conversion practices, namely, 1) a control plot still tilled with a crop (maize), 2) a folder grass-growing plot seeded with Lolium perenne , 3) a young alder tree-growing plot, 4) a pear orchard plot and 5)a bamboo plot intercropped with folder grass, were monitored to compare the soil conservation efficiency of those changes in Ya'an, Sichuan for 3 years between September 1998 and August 2001. Results showed that the 5 designed converting models functioned differently in erosion control. The most effective model was bamboo groves intercropped with folder grass (Lolium perenne). The folder grass (Lolium perenne) growing model was more effective than the pure pear orchard model. The least effective model was the young alder tree-growing slope, which was even less effective than the control (a slope without converted cultivation). Meanwhile, changes in the soil's physical properties r