Scaling ethnic segregation: causal processes and contingent outcomes in Chinese residential patterns

This paper advances a contingent perspective of residential segregation that recognizes it as a universal phenomenon of residential differentiation, yet one that results from different causal processes and which results in different spatial outcomes. The analytical separation of groups, contexts and scale is key to understanding the nature of segregation, i.e., what it signifies to the group and to the host society. We argue that segregation is created and maintained by different choices and constraints occurring across dimensions of production, reproduction and consumption. Spatial outcomes vary considerably, and may be arrayed in regard to the permanence of segregation, whether it facilitates identity maintenance, and whether segregation itself empowers or marginalizes the ethnic population. To demonstrate our approach, we analyze the segregation experiences of Chinese ethnics. Our argument is organized around the global, national and local scales at which causal processes shape the Chinese experience of segregation.     

A constitutive model for granular materials with grain crushing and its application to a pyroclastic soil

A constitutive model for granular materials is developed within the framework of strain–hardening elastoplasticity, aiming at describing some of the macroscopic effects of the degradation processes associated with grain crushing. The central assumption of the paper is that, upon loading, the frictional properties of the material are modified as a consequence of the changes in grain size distribution. The effects of these irreversible microscopic processes are described macroscopically as accumulated plastic strain. Plastic strain drives the evolution of internal variables which model phenomenologically the changes of mechanical properties induced by grain crushing by controlling the geometry of the yield locus and the direction of plastic flow. An application of the model to Pozzolana Nera is presented. The stress–dilatancy relationship observed for this material is used as a guidance for the formulation of hardening laws. One of the salient features of the proposed model is its capability of reproducing the stress–dilatancy behaviour observed in Pozzolana Nera, for which the minimum value of dilatancy always follows the maximum stress ratio experienced by the material. Copyright © 2002 John Wiley & Sons, Ltd.     

Understanding land-use/cover change process for land and environmental resources use management policy in Ghana

Accurate information on land-use/cover change is a critical input for natural resource use management policy decisions. In Ghana, however, land-use/cover change is premised on the assumption that there has been a historically simple, linear, and uniform degradation of vegetation across all landscapes. The Kintampo and neighboring districts have become a subject of intense debate as to the real nature of prevailing land cover changes .It is commonly assumed that there is ubiquitously progressive irreversible woody vegetation loss across the area. The paper reports on the process and amount of land-use/cover changes that have prevailed in specific localities across the area within a 10-year period. It is hoped this will improve understanding and management of land-use/cover change in Ghana. Remote sensing and Geographic information systems technologies were used for the investigation. A multi-site satellite imagery approach was adopted to ensure that inductive inferences could be made. The outcome of the study indicated that, in space and time, there have been significant land-use/cover changes. Variability in change was a constant, rather than occasional feature across these human dominated landscapes. The conversion and transformation processes indicated that the traditional land-use strategies are self-sustaining. Any effective land-use/cover management strategy should be built upon the existing traditional farming system knowledge and practices.     

Geology and the dark side

The diabolical and supernatural folklore traditions of geology are examined systematically for the first time. The following have all been suggested explanations for fossil remains: Devil's footprints, bones, toenails, fingers, thumbs, buttons, money and ninepins; Hobgoblin's claws; Fairy's fingers, heads, faces, hearts, beads, causeways, saltcellars, bottles, weights, money and loaves; elf arrows; witches’ beads and tongues. Twinned staurolite crystals have been called Fairy crosses.     

Geomagnetic anomaly at Lunping before the 1999 Chi-Chi earthquake (M w = 7.6) in Taiwan

A strong earthquake with a magnitude of 7.6 (M _L  = 7.3) occurred on September 21, 1999, in central Taiwan. In order to discern any potential precursors before this earthquake, geomagnetic data at Lunping (LNP), Taiwan, Geomagnetic Observatory situated 100 km from the epicenter are examined using two methods, i.e., the traditional induction arrows and complex demodulation. Our results show that the remarkable temporal variation of real induction arrows appear to be strong prior to the great earthquake over the previous 24 months. After the great earthquake, the magnitudes of induction arrows decreased to the normal (mean of 8 years) levels. In other words, the direction of real induction arrows of the periods 30 and 20 min rotated 85° and 40° anticlockwise, respectively, before the Chi-Chi earthquake and returned to mean direction of last 10 years after the earthquake. A horizontal source field model using the finite difference method for 3-D shows that the variation of the real induction arrows might be ascribed to the conductivity variation body, which is 5 km buried at the epicenter area of the Chi-Chi earthquake, changing its conductivity from 0.002S/m to 0.06 S/m. The ratios of modulus (demodulated by using the complex demodulation method) over a period 12, and 8 h relative to the period of 24 h reveal a remarkable change that appeared 4–5 months prior to this strong earthquake. They increased gradually from the beginning of 1999 to August 1999 and decreased again to a (8 years) mean level after the strong earthquake occurrence. We consider that the variation of the induction arrow might be ascribed to the conductivity anomaly, which is buried 5 km at the south-east side of LNP with a conductivity change of 0.06 S/m. We propose that this elevation might be related to the preparation process of the great earthquake.     

太沙基方程Laplace解

根据饱和土单向渗透固结的特殊规律,以外荷一次性施加,初始超静水压u₀等于常数,顶面透水,用底部超静水压力u在任意时刻为有限值这个事实,代替底部边界排、隔水条件等简化假定,作为简单情况下太沙基单向固结微分方程的初始和边界条件.对太沙基单向固结微分方程进行拉氏积分变换求解.得到超静水压力u、固结度U、平均固结度U结论式.客观地反映了土层固结过程中u、U、U,随Z、t的变化规律,且形式简洁,使用方便,有效可行.     

Cumulative Benioff strain-release, modified Omori's law and transient behaviour of rocks

Irreversible thermodynamic theories with internal state variables can be used to derive a general constitutive law for both transient and steady-state behaviours of rocks. This constitutive law can represent the concepts of damage and damage evolution in either the fibre-bundle model or continuum damage mechanics. We have previously proposed an empirically based constitutive law for both the transient and steady-state behaviours of rocks ultimately derived from laboratory experimental data. We show here that this law is concordant with the general constitutive law derived from irreversible thermodynamic theories, and that the relaxation modulus has a temporal power–law that depends on a structural fractal property of rocks. Our constitutive law predicts forms for the cumulative Benioff strain-release for precursory seismic activations and the modified Omori's laws of aftershocks, both aspects of the temporal fractal properties of seismicity. These seismic properties can also be derived by the fibre-bundle model or continuum damage mechanics. Our model suggests that these time-scale invariant processes of seismicity may be regulated by the fractal structures of crustal rocks.     

Compound-specific isotopic analyses: a novel tool for reconstruction of ancient biogeochemical processes

Patterns of isotopic fractionation in biogeochemical processes are reviewed and it is suggested that isotopic fractionations will be small when substrates are large. If so, isotopic compositions of biomarkers will reflect those of their biosynthetic precursors. This prediction is tested by consideration of results of analyses of geoporphyrins and geolipids from the Greenhorn Formation (Cretaceous, Western Interior Seaway of North America) and the Messel Shale (Eocene, lacustrine, southern Germany). It is shown (i) that isotopic compositions of porphyrins that are related to a common source, but which have been altered structurally, cluster tightly and (ii) that isotopic differences between geolipids and porphyrins related to a common source are equal to those observed in modern biosynthetic products. Both of these observations are consistent with preservation of biologically controlled isotopic compositions during diagenesis. Isotopic compositions of individual compounds can thus be interpreted in terms of biogeochemical processes in ancient depositional environments. In the Cretaceous samples, isotopic compositions of n-alkanes are covariant with those of total organic carbon, while delta values for pristane and phytane are covariant with those of porphyrins. In this unit representing an open marine environment, the preserved acyclic polyisoprenoids apparently derive mainly from primary material, while the extractable, n-alkanes derive mainly from lower levels of the food chain. In the Messel Shale, isotopic compositions of individual biomarkers range from -20.9 to -73.4% vs PDB. Isotopic compositions of specific compounds can be interpreted in terms of origin from methylotrophic, chemautotrophic, and chemolithotrophic microorganisms as well as from primary producers that lived in the water column and sediments of this ancient lake.     

Geo-historical Trajectories of Democratic Transition: The Case of Nigeria

There has been a long-term, halting diffusion of the liberal democratic state. The literature on democratization, however, tends to underplay issues of geo-historical context. This paper addresses the relationship between geo-historical context and democratization through a case study of Nigeria. Key contextual factors of transition discussed include: international pressure for democratization, geo-political dynamics of pro-democracy coalitions, and local and trans-local political economic relationships. Nigeria under the military governments of Babangida and Abacha (1985–1998) was in a perpetual half-hearted state of transition to democracy. The country's status as a major oil exporter allowed it relative immunity from international pressure for democratization. Beyond repression and neo-patrimonialism, both governments deployed a distinctly spatial resistance strategy, that of state creation. The generals tried to shift attention away from regime failures and excesses, notably the illegitimacy of military rule and economic decline. Mobilization for state creation served to divide opposition to military government because it focused attention at the local scale, as new state movements competed for access to centrally controlled resources and political recognition of their ethno-regional group(s). This transition period produced several legacies for Nigeria's Fourth Republic (1999-). These include: a dysfunctional national state apparatus; problems of national disunity; and a stagnant economy. These legacies of transition present major obstacles to national development and the consolidation of a liberal democratic state. The Nigerian case points to a broader need for an understanding of geo-historical context in assessing prospects for the spread of democracy. This revised version was published online in August 2006 with corrections to the Cover Date.     

On the term “soft-sediment deformation”

The term “soft-sediment deformation” includes a range of processes and resulting structures whose breadth is only now being recognized. The phrase is therefore often misleadingly loose and fails to convey the nature of the process or structure being reported. Various difficulties, especially the masking of the nature of the material at the time of deformation by later changes, preclude rigorous definitions, but more careful usage is urged. The kind of structure should be specified. The softness of the material is suggested to be equivalent to its cohesion, which in near-surface sediments might be judged from the form of the structure. Inclusion of words such as early or late would help clarify the timing. Of particular growing need is an indication of the generating force, which could derive from some local movement, from gravity, or from tectonism, all of which are now known to act on unlithified material.     

Hummocky cross-stratification, tropical hurricanes, and intense winter storms

Duke (1985b) argues that ‘most examples (of hummocky cross-stratification) were formed by tropical hurricanes.’ His statement is based on the assumption that ‘hurricane-generated surface gravity waves form powerful oscillating or multidirectional flows at the water-sediment interface which do not possess a significant unidirectional component.’ It is true, as one of us has previously stated, that hurricanes are rapidly-moving, short-lived, localized, and infrequent systems as compared with mid-latitude storms; midlatitude storms are consequently more efficient in coupling with the shelf water-column than are hurricanes. However, Duke's argument that hummocky cross-stratification may be the result of purely oscillatory flow is untenable. His reasoning contradicts established theory about oscillatory bedforms, and his numerous examples of hummocky cross-stratification come largely from continental shelf settings where the storms (tropical or otherwise) would have created concurrent alongshelf undirectional flow as well as wave oscillatory motion. There is no theoretical or observational basis for the belief that water movement on the sea-floor during hurricanes is qualitatively different from water movement during mid-latitude storms. Consequently, hummocks are no more liable to form beneath hurricanes than they are beneath mid-latitude storms.     

The ascent of the anthropostrome: A point of view on the man-made environment

The anthropostrome is used to denote the collective constructs of human artifacts and is characterized by repetitive geometrical moduli, centralized energetic cyclons, and constrictive restraints to functional freedom of both human and non-human elements. This unified, self-perpetuating, man-made environment is a high-level integrative structure where organism-like features are developing while ocosystem-like features persist. Due to pervasive integration, urban-industrial men generally fail to perceive the colonial nature of the autonomous unit which produced them Direct contacts with the world outside the anthropostrome are scare, and most information and sensory experience are supplied by the anthropostrome itself In spite of temporary or localized regressions, the global trend is apparently toward growth of the total anthropostrome Expansion of urban systems will presumably be accelerated until environmental degradation and resource shortages act as natural constraints The need for containment of the anthropostrome’s growth and for control of its swift noogentic development while avoiding injury to men is possibly the next challenge to man’s evolutionary potential     

地体的单向和多向聚合与离散

地体构造是对板块构造理论的发展和补充,它受控于全球板块动力学体系,因此不能将地体与板块割裂开来去研究.其相对于刚性板块的小规模、多样性和广泛性,对了解全球板块的离散和大陆的拼贴增生过程具有十分重要意义.地体构造无处不在,它不仅存在于中、新生代陆缘造山带中,也存在于古老造山带中,一些古老的克拉通实际上也是由不同的地体拼合...     

A unified model for bedform development and equilibrium under unidirectional,oscillatory and combined‐flows

The development of bedforms under unidirectional, oscillatory and combined‐flows results from temporal changes in sediment transport, flow and morphological response. In such flows, the bedform characteristics (for example, height, wavelength and shape) change over time, from their initiation to equilibrium with the imposed conditions, even if the flow conditions remain unchanged. These variations in bedform morphology during development are reflected in the sedimentary structures preserved in the rock record. Hence, understanding the time and morphological development in which bedforms evolve to an equilibrium stage is critical for informed reconstruction of the ancient sedimentary record. This article presents results from a laboratory flume study on bedform development and equilibrium development time conducted under purely unidirectional, purely oscillatory and combined‐flow conditions, which aimed to test and extend an empirical model developed in past work solely for unidirectional ripples. The present results yield a unified model for bedform development and equilibrium under unidirectional, oscillatory and combined‐flows. The experimental results show that the processes of bedform genesis and growth are common to all types of flows, and can be characterized into four stages: (i) incipient bedforms; (ii) growing bedforms; (iii) stabilizing bedforms; and (iv) fully developed bedforms. Furthermore, the development path of bedform; growth exhibits the same general trend for different flow types (for example, unidirectional, oscillatory and combined‐flows), bedform size (for example, small versus large ripples), bedform shape (for example, symmetrical or rounded), bedform planform geometry (for example, two‐dimensional versus three‐dimensional), flow velocities and sediment grain sizes. The equilibrium time for a wide range of bed configurations was determined and found to be inversely proportional to the sediment transport flux occurring for that flow condition.     

Relationship between aquatic insects and heavy metals in an urban stream using multivariate techniques

In the study, the relationship between some aquatic insect species (Ephemeroptera, Plecoptera, Trichoptera and Odonata) and some heavy metals (cadmium, lead, copper, zinc, nickel, iron and manganese) and boron were assessed using data obtained from the Ankara Stream, which flows through Ankara, the capital city of Turkey and receives high organic and industrial wastes. Sampling was carried out monthly along the Ankara Stream in 1991. environmental data were used to explain biological variation using multivariate techniques provided by the program canonical correspondence analysis ordination. The ordination method canonical correspondence analysis was applied to evaluate the relationships between environmental variables and distribution of aquatic insect larvae. Data sets were classified by two way indicator species analysis. In this study, aquatic insecta communities have been shown by canonical correspondence analysis ordination as related to total hardness, pH, cadmium, lead, copper, zinc, nickel, iron, manganese and boron. Cadmium, lead, copper and boron exceeded limits of the United States Environmental Protection Agency criteria for aquatic life. Trichopteran, Dinarthrum iranicum was an indicator of two way indicator species analysis and was placed close to the arrow representing copper. Odonate, Aeschna juncea was an indicator of two way indicator species analysis in site 10 and was placed close to the arrows representing manganese, lead, and nickel. Trichopteran, Cheumatopsyche lepida and odonate, Platycnemis pennipes were indicators of two way indicator species analysis for sites 6, 7, 11, 14, 15, 18 and were placed close to the arrows representing cadmium, boron, iron and total hardness.     

关于滑坡稳定性在滑坡安全系数取值中的作用讨论

在工程界存在着滑坡安全系数取值应考虑滑坡稳定性高低、对稳定系数较低的滑坡应采用较大的安全系数的思想。考虑滑坡稳定性的具体方式有两种:①考虑滑坡的实际稳定状态或变形情况;②考虑设计工况下的稳定系数。考虑滑坡稳定性的理由也有两种:①变形急剧势必危害较大;②滑坡在治理后的安全储备可用"安全储备系数"(即下滑力按安全系数放大后的剩余下滑力与下滑力不作改变时的剩余下滑力之比)来衡量,而"安全储备系数"存在着随稳定系数的减小而减小的规律。文章的研究表明,滑坡变形越急剧滑坡危害越大的规律是不存在的,滑坡"安全储备系数"既不能衡量滑坡在治理后的安全储备,也不随滑坡稳定系数的减小而减小,滑坡安全系数与稳定系数无关,将安全系数取值与稳定系数大小挂钩会导致诸多不合理现象产生。因此,滑坡安全系数取值不应考虑稳定系数大小。     

深海沉积与全球变化研究的前缘与挑战

海洋正在经历变暖和酸化等人类活动引发的全球变化的影响,而深海沉积储存着地球演变历史时期由自然因素驱动过去全球变化的详细档案,通过探究其现今和过去全球变化过程,能够揭示全球变化的特征和规律,为预测未来变化提供依据。近年来在该领域的突出研究进展,是针对社会选择的未来排放轨迹,在深海记录中都能够找到相应的类似情形,用于评估未来地球系统各种变化的过程和后果。其中,以Dansgaard-Oeschger变化为代表的千年尺度事件、以厄尔尼诺-南方涛动(ENSO)和北大西洋涛动(NAO)为代表的十年尺度气候变化事件,是最接近现今地球变暖的快速气候变化场景。地球系统的发展轨迹目前正处于人类排放温室气体的“热室地球”路径的起点上,如果地球超过了这个“临界点”,它将沿着一条不可逆的道路进入“热室地球”状态,另一种路径则是通向“稳定地球”状态。深海沉积档案中的类似情形能够为社会选择未来排放的轨迹提供重要参考。全球变化研究面临的重大挑战是重新认识其关键过程的理论机制。以海洋变暖和酸化影响硅藻和颗石藻的海洋生物泵过程为例,传统知识认为酸化有利于硅藻建造,但最新的围隔实验研究却发现酸化大幅减少全球硅藻输出;传统知识认为酸化导致海洋生物钙化危机,但近期针对中生代大洋缺氧事件的黑色页岩研究,发现颗石藻的碳酸钙输出在海洋酸化期间大幅增加。这些颠覆性的认识严重挑战了传统全球变化某些关键过程的理论体系。     

The geosynclinal process and evolution of tectonosphere

Intrusion, sedimentation and metamorphism constitute a continuous distillation process in the lithosphere; these processes are reversible. An irreversible tectonic process, however, is superimposed upon this cycle; this involves an increase in the thickness of the mantle, due to geosynclinal development, an increase in the depth of the boundary between tectonic and phase change processes, and therefore an increase in the depth at which rock will melt. The Galitzin discontinuity is probably the present boundary between mantle and crust. - M. E. Burgunker.     

National sovereignty & transboundary protected areas in Southern Africa

The notion that Transboundary Protected Areas (TBPAs) will act as `Peace Parks' has become an important argument in their promotion in post-Apartheid Southern Africa. This `Peace Parks Concept' is implicitly based upon the assumption that national sovereignty will not become a constraining factor in the creation and management of TBPAs. However, this assumption is problematic. TBPAs introduce various changes in the landscape with consequences for the ways in which a state can exercise its sovereignty over its borderland and citizens. This situation might evoke state action that could endanger the various environmental, socio-economic and political objectives of TBPAs. A state's behaviour with regard to TBPAs is not just informed by its interests in TBPAs, but also by its strategic and other interests in the wider borderland area. These are not necessarily compatible with the environmental and economic objectives of TBPAs. The ways in which these interests are mediated are highly complex and non-linear. Because of the inter-dependency that TBPAs create, the extent to which a state can pursue certain interests by means of TBPAs will be (partially) constrained by the wishes of the other states involved. In addition, power has to be shared with a wide range of non-state actors. The operation of sovereignty in TBPAs is therefore highly unpredictable and cannot be captured in static zero-sum terms. Actor Network Theory is identified as a possible starting-point to unravel and evaluate these complex political processes in TBPAs and their subsequent outcomes for state sovereignty.