Effects of Fe and Al incorporations on the bridgmanite–postperovskite coexistence domain

The postperovskite phase transition of Fe and Al-bearing MgSiO₃ bridgmanite, the most aboundant mineral in the Earth's lower mantle, is believed to be a key to understanding seismological observations in the D″ layer, e.g., the discontinuous changes in seismic wave velocities. Experimentally reported phase transition boundaries of Fe and Al-bearing bridgmanite are currently largely controversial and generally suggest wide two-phase coexistence domains. Theoretical simulations ignoring temperature effects cannot evaluate correctly two-phase coexistence domains under high-temperature. We show high-pressure and high-temperature phase transition boundaries for various compositions with geophysically relevant impurities of Fe²⁺SiO₃, Fe³⁺Fe³⁺O₃, Fe³⁺Al³⁺O₃, and Al³⁺Al³⁺O₃ derived from the ab initio finite-temperature free energies calculated combining the internally consistent LSDA + U method and a lattice dynamics approach. We found that at ～ 2500 K, incorporations accompanied by Fe³⁺ expand the two-phase coexistence domains distinctly, implying that D″ seismic discontinuities likely arise from the phase transition of Fe²⁺-bearing bridgmanite.     

大金湖国家地质公园GIS地理空间元数据设计研究

大金湖国家地质公园地理信息系统的建立与运行都需要元数据的支持。文中在对大金湖国家地质公园地理信息数据分析的基础上,应用现有的元数据标准,对其地理空间元数据的内容信息、管理模式、应用扩展进行了设计研究。     

云南龙陵勐糯铅锌矿床中镉元素赋存状况

矿床中镉元素异常明显,以硫镉矿、不规则粒状、脉状充填嵌布于闪锌矿中。提出矿石生成顺序,为进一步找矿提供新依据。     

Rethinking graduated citizenship: Contemporary public housing in Singapore

The ways in which citizenship and housing are implicated in states’ global city aspirations demonstrate significant path dependency and local contingency. This paper serves to broaden the literature that has been dominated by the Western neoliberal context. First, I argue that The Pinnacle@Duxton – a one-of-a-kind public housing project in Singapore – represents the developmental state’s attempt to graduate its homogeneous public housing landscape, providing for and subsidizing the aspirations of a segment of its increasingly affluent middle class to buy into the ideology of the global city. Second, I show how the graduation of public housing coupled with the exaggerated demand for such exclusive projects validates consumer preference pricing in contemporary public housing. This results in a geographical graduation of citizenship, where the bulk of the population is relegated to lesser options on the edges on the island, unable to fulfil their aspirations for global living. In so doing, I make two contributions to extant literature on housing and citizenship in the global city. One, graduating citizenship is not always a case of states realigning their relationship with their citizens to fit the terms of the market. Two, the denial of citizenship to the global city does not always manifest in terms of substantive rights. Appreciating the unique histories and ideologies underpinning housing policies in global cities is instrumental if the variegated meanings of global cities and the citizenships within are to be elucidated.     

Teaching Methods,the Herbartian Revolution and Douglas Clay Ridgley at Illinois State Normal University

Abstract

Teaching methods in the 1880s and 1890s were influenced by the energies and publications of the Herbartians from Illinois State Normal University. Memorization was replaced by inductive questioning, field trips and the use of visual aids. Four men and one woman were followed by Douglas Clay Ridgley who built up the geography major and made tools for the teachers. Name recognition is now weak but much of what they taught is now accepted and practiced.     

Second-order state transition for relative motion near perturbed,elliptic orbits

This paper develops a tensor and its inverse, for the analytical propagation of the position and velocity of a satellite, with respect to another, in an eccentric orbit. The tensor is useful for relative motion analysis where the separation distance between the two satellites is large. The use of nonsingular elements in the formulation ensures uniform validity even when the reference orbit is circular. Furthermore, when coupled with state transition matrices from existing works that account for perturbations due to Earth oblateness effects, its use can very accurately propagate relative states when oblateness effects and second-order nonlinearities from the differential gravitational field are of the same order of magnitude. The effectiveness of the tensor is illustrated with various examples.     

三维地学模拟几个方面的研究现状与发展趋势

对三维地学模拟中的三维空间数据模型,三维地学模拟技术以及三维地学模拟软件的应用３个方面的研究现状进行了总结,并指出了发展趋势与研究思路。     

The emerging Islamic State: Terror,territoriality, and the agenda of social transformation

The world has recently been witness to the emergence of a new contemporary geopolitical phenomenon: the declaration of Islamic States by specific Islamic organizations. This phenomenon has the potential to dramatically transform the geopolitical setting of the Middle East and to have farreaching effects on a global level. Of these most prominent, however, has undoubtedly been the June 2014 declaration by the “Islamic State” organization of a “caliphate” covering large areas of the two war-torn states of Syria and Iraq. The aim of this article is to interrogate the territorial aspects of the Islamic State and to discern what makes it unique and exceptional in comparison to the many other Islamic political organizations that have emerged in recent years. In order to facilitate a better understanding of territoriality, I distinguish here between two major dimensions: conceptions of territoriality and tactics of territoriality. My working assumption is that by distinguishing between conceptions and tactics of territoriality, we can compare the exercise of territoriality by states and, in the present case, organizations. In this article, I argue that the Islamic State poses a challenge to both the conceptual and tactical dimensions of the contemporary territory and territoriality of modern states. Yet, while its conception of territoriality may be widely shared by other political Islamic organizations, its uniqueness lies in its tactics and strategies. Indeed, it is the brutal tactics of the Islamic State that are less acceptable to many Muslims around the world, not its political conception, which enjoys considerable support in the Muslim arena. Yet, when comparing it with modern states, the Islamic State poses a challenge to the territory and territoriality in both conception and tactics.     

论采矿权的物权特征

物权是现代社会经济生活中极为重要的权利。运用物权原理论述了采矿权作为财产性权利所具有的他物权、排他性、不动产权、用益物权特征,并阐述了采矿权与矿产资源国家所有权的关系,分析了采矿权物权特征在我国采矿权法律制度中的重要作用。