Are people of Indian origin (PIO) “Indian”? A case study of South Africa

A necessary condition for a migration to be considered as a “diaspora” is the upholding of contacts in the land of origin in various forms, real or imaginary, material or cultural. This paper examines whether this is so in the case of Indian South Africans, most of whose ancestors came to the country as indentured labourers between 1860 and 1911. A key contention was that there could be some cultural and emotional factors partly explaining the economic relations and the geography of flows between the South Africans of Indian origin and India. However, this eventually proved to be wrong. This is all the more paradoxical since the “Indian” identity is still very alive in Durban. However, it is highly fragmented, according to the generations, the religions and the socio-economic classes. India is still a key referent, but “transcendentally”: either as a country which has only an abstract existence, which is spoken of, even dreamt of, without ever being visited; or it is visited but considered only as a whole, since the region of one’s ancestors is almost never at the forefront. Furthermore, the vulnerable situation of “Indians” within South African society does not encourage stronger relationships with India.     

Contaminant dispersion at the rehabilitated Mary Kathleen uranium mine, Australia

This study reports on the transfer of contaminants from waste rock dumps and mineralised ground into soils, sediments, waters and plants at the rehabilitated Mary Kathleen uranium mine in semi-arid northwest Queensland. Numerous waste rock dumps were partly covered with benign soil and the open pit mine was allowed to flood. The mineralised and waste calc-silicate rock in the open pit and dumps has major (>1 wt%) Ca, Fe and Mg, minor (>1,000 ppm) Ce, La, Mn, P and S, subminor (>100 ppm) Ba, Cu, Th and U, and trace (<100 ppm) As, Ni, Pb, Y and Zn values. Consequently, chemical and physical weathering processes have acted on waste rock and on rock faces within the open pit, mobilising many elements and leading to their dispersion into soils, stream sediments, pit water and several plant species. Chemical dispersion is initiated by sulfide mineral breakdown, generation of sulfuric acid and formation of several soluble, transient sulfate minerals as evaporative efflorescent precipitates. Radiation doses associated with the open pit average 5.65 mSv year⁻¹; waste dumps commonly have lower values, especially where soil-covered. Surface pit water is slightly acid, with high sulfate values accompanied by levels of U, Cu and Ni close to or above Australian water guideline values for livestock. Dispersion of U and related elements into soils and stream sediments occurs by physical (erosional) processes and from chemical precipitation. Plants growing in the mine void, on waste dumps and contaminated soil display evidence of biological uptake of U, LREE, Cu and Th and to a lesser degree of As, Ni, Pb, Y and Zn, with values being up to 1–2 orders of magnitude above background sites for the same species. Although rehabilitation procedures have been partly successful in reducing dispersion of U and related elements into the surrounding environment, it is apparent that 20 years after rehabilitation, there is significant physical and chemical mobility, including transfer into plants.     

Effective porosity and specific yield of a sedimentary rock determined by a field tracing test using tritium as a tracer

Effective porosity value was analyzed from the tritium concentration of sampled groundwater using a three-dimensional groundwater-flow and advection-dispersion code based on the finite element method. The effective porosity value was about 10%. Porosity values measured from core samples were 7–15%. The groundwater flow velocity estimated from the tritium concentrations was about 1 × 10^–5 cm s^–1. Therefore, during the low groundwater flow velocity condition, effective porosity and porosity values were the same. At the same test site, a 0.48% effective porosity value, determined by another tracer test injecting Br^– solution into the aquifer during groundwater level change, was smaller than the porosity value when the flow velocity was 1.8×10^–2 cm s^–1. Thus the effective porosity value is concluded to be due to groundwater flow velocity. The specific yield value was calculated to be 0.6% by the total volume of tunnel seepage water and the total volume of the rock unsaturated during tunnel construction. However, as pore water continued to be drained after the groundwater level change was completed, the specific yield value became larger than 0.6%. Thus specific yield value is concluded to be due to drainage time.     

施甸5级震群前中短-短临的地震活动参数动态演化

通过2001年施甸5级震群前地震学各项参数异常的动态追踪，研究了中强地震孕育、发生的中短—短临的演化过程。结果表明：在云南地区出现b值、小震调制比、波速比等地震活动性参数异常以及中强地震的有规律迁移的中期异常背景上，出现了孕震区的频度、b值、应变加速等群体中短异常，以及云南省内的3、4级地震连续增频、3级日频次异常和显的3、4级地震平静的短临异常。特别是3、4级地震异常平静，标志了明显的临震信息，并初步探讨了中强地震连续发生中如何识别单个地震的震兆问题。     

求解波动方程的任意差分精细积分法

在地震偏移成像技术中，常常要反向外推波场，因此涉及到波动方程的数值求解问题。本文提出了一种求解偏微分方程的新的半解析方法——任意差分精细积分(ADPI)法。其大体思路是：空间域上作坐标离散，但不采用古典差分法的等分离散方式，而是一种相对自由的、任意的离散法；时间域上则采用子域精细积分的方法，既保留了精细积分法的高精度，又克服了工作量大、占用存储大等缺点。该方法具有精度高、带宽小、稳定性好等多项突出优点，并且可以灵括处理各类边界条件。本文从简单一维、较普遍一维、以及二维3种情形讨论该方法对波动方程的具体应用，结合实际的算例，详细分析了各种算法的可行性和精度特点。     

Scenarios for the Future Population of Sydney

The period 1996-2001 has witnessed a refocusing of population growth on Sydney and Melbourne as both cities have developed significant concentrations of so-called 'new economy' jobs and taken on, to greater or lesser extents, the characteristics of global cities. The consequence of these trends, for Sydney most particularly, is population growth. This paper establishes this demographic reality by describing recent demographic trends in Sydney and possible future scenarios for Sydney's population, given differing levels of fertility, internal migration and international migration. A related future trend is also traced--that the number of households in Sydney will grow more rapidly than the population due to changes in household structure. This raises the issue of how and where these households will be accommodated, given the relative land shortage in the Sydney Statistical Division and given that there is no doubt that planners in New South Wales will be attempting to maintain and enhance Sydney's status as a global city. In sum, the paper argues that Sydney planners should be preparing for growth of around one million people in the next 20 years and a further one million in the following 30 years. To maintain that potential future residents of Sydney can be redirected to other parts of New South Wales is a vain hope.     

利用微震数据对震源下方构造直接成像

现有的微震记录直接成像方法是将微震记录既当作入射记录,也当作散射记录,从而实现偏移成像.但此方法并不能突出透射波所携带的来自震源下方的深层散射波信息.本文在假设已知微震位置与子波的前提下,提出了对微震下方构造进行逆时偏移的成像方法.该方法类似于常规的逆时偏移,只是震源位置在地下.这使得在成像时,地下更深部的入射波场相比震源在地表时会更为精确,因此能够获得更加准确的成像结果.该方法会给成像结果带来一种尾波高频干扰：地下的震源发出的上行波与上方介质作用后,所产生的多级散射波会干扰反传波场.对此,在成像过程中,对入射场和散射场都进行左右行波分离,以压制该噪声.而在子波信息未知,无法重构入射场时,使用了激发时间成像条件,也能够实现同等效果的偏移成像,且不会出现尾波高频干扰.利用数值实验验证了本文方法的有效性.     

地应力与油气运移

本文途述了地应力作用下引起的岩石变形及孔隙压力,给出了孔隙岩层中流体的微分方程及有限元公式。在地应力测量及应力场模拟的基础上对辽河油田进行了运移势场的计算,为油气勘探开发提供依据。      

Pharmaceuticals and personal care products transference-transformation in aquifer system

Pharmaceuticals and personal care products (PPCPs) are a new kind of contaminant widely existing in the surface water and groundwater environment. In recent years, PPCPs have been received widely attention from many researchers. The migration and transformation of PPCPs are mainly photolysis, biodegradation, adsorption and hydrolysis in aquifer environment. The influencing factors of PPCPs migration include PPCPs' own physical and chemical properties, types and contents of organic matter, pH, lithology, geotechnical structure and the thickness of vadose zone, etc. At present, the research of PPCPs in China is still in the primary stage, especially on the contaminant in aquifer system. Therefore, the research in this field needs to be further strengthened.