Assembling/Worlding Cities     

Eugene McCann  Ananya Roy 《Urban geography》2013,34(5):581-589

This article explores the assembling and worlding of cities as both aspirational and evaluative processes in which cities are assembled, compared, and “positioned.” These practices involve the global circulation of expertise, best practices, models, and technologies related to how best to develop and govern cities. From specific examples from the authors' research, it is argued that the two distinct but overlapping notions of assembling and worlding help us conceptualize the contemporary urban–global condition. Building on the article's insights, we end this Urban Pulse with some questions for future global urban studies.  相似文献   

Actor-networks and implementation: examples from conservation GIS in Ecuador     

Eugene W. Martin 《International journal of geographical information science》2013,27(8):715-738

Recommendations for implementation and evaluation of Geographical Information Systems (GIS) can benfit from a broader theoretical foundation to support investigation, understanding and improvement. This paper discusses Actor-Network Theory (ANT) as a framework to delineate and evaluate the social and technical interactions involved in GIS implementation. The proposed process traces actor-network interactions through texts, technical objects, people, money and control. Actor alignment, actor-network stability and obligatory points of passage are evaluated to compare actor-networks. Case study research on conservation GIS implementation in Ecuador illustrates these methods. The strength of these actor-networks is examined through analysis of actors' interactions and the presence and function of an obligatory point of passage. Stronger actor-networks exhibit alignment among actors, co-location of an obligatory point of passage with the center of calculation and credit sharing.  相似文献   

Post‐Late Paleozoic Collisional Framework of Southern Great Altai   总被引：1，自引：0，他引：1  

Boris M. CHIKOV  Sergei V. ZINOVIEV  Еugene V. DEYEV 《《地质学报》英文版》2012,86(5):1093-1104

We outline the post-Late Paleozoic (latest Permian to Cenozoic) collisional framework of the southern Great Altai (Central Asia) produced by the convergence between the Tuva-Mongolia and Junggar continental terranes (microplates). The collisional structures in the region classified on the basis of their geometry and deformation style, dynamic metamorphism, and compositions of tectonites are of three main types: (1) mosaic terranes made up of large weakly deformed Paleozoic blocks separated by younger shear zones; (2) contractional deformation systems involving structures formed in post-Late Paleozoic time, parallel faults oriented along collisional deformation systems, and relict lenses of Paleozoic orogenic complexes; and (3) isolated zones of dynamic metamorphism composed mostly of collisional tectonites different in composition and alteration grade.  相似文献   

64层锥束CT扫描的优化系统     

谢强  Eugene Williams  唐向阳  Brian Grekowicz  Roy Nilsen  Sandeep Dutta  Robert Senzig 《CT理论与应用研究》2005,14(4):59-67

近年来X射线断层成像(CT)技术获得了突飞猛进的发展,自1998年推出4层螺旋CT后,CT扫描设备在容积覆盖,空间分辨率,扫描速度,切片数方面取得了长足进展.这不仅给医学应用带来了深远的影响,同时也给CT系统设计提出了巨大的挑战.容积CT(VCT)的设计过程引入了各种策略来战胜其复杂性.这些方法学包括:理论分析,系统性能预测的图像分析工具,各种基于专家背对背评价的参数优化.本文论述了64层CT系统设计中的一些考虑因素及优化过程.这些设计过程保证了锥束CT的优化性能.首批客户的应用反馈显示了我们设计实践的有效率性.  相似文献   

The morphological response of foredunes at a breached barrier system to winter 2013/2014 storms on the southwest coast of Ireland          下载免费PDF全文

Sarah Kandrot  Eugene Farrell  Robert Devoy 《地球表面变化过程与地形》2016,41(14):2123-2136

The level of storminess in Ireland during the winter of 2013/2014 was exceptional, the effects of which cost the Irish state in excess of €260 million in infrastructure repair and insurance claims. In Ireland, a lack of coastal process data from monitoring programmes means that the response of protective barrier coasts to such events remains largely un‐investigated. This study addresses this issue through an examination of the geomorphic impacts of recent storms, including those that occurred during the winter 2013/2014, on a breached barrier on the southwest coast of Ireland. Data from a two‐year terrestrial laser scanning (TLS) monitoring campaign shows that the winter 2013/2014 events caused a major (>50 m) dune recession at Rossbehy, County Kerry. Results from a simple linear regression analysis indicate storm duration plays an important role in the removal of foredunes at the study site. Given the fact that the frequency of intense storms in the vicinity of Ireland is forecast to increase within the next century, a scientific understanding of barrier response to such events is critical to inform sound management practices. Copyright © 2016 John Wiley & Sons, Ltd.  相似文献   

Comments on Buzan et al. “Positive Relationships between Freshwater Inflow and Oyster Abundance in Galveston Bay,Texas”     

R. Eugene Turner 《Estuaries and Coasts》2009,32(1):213-217

Buzan et al. critique Turner’s (Estuaries and Coasts 29:345–352, 2006) analysis of the relationship between freshwater inflow and oyster productivity in the Gulf of Mexico, using 16 years of fisheries-independent data for Galveston Bay. They conclude that the catch-per-unit effort (CPUE; number h⁻¹) of marketable oysters increase 1 to 2 years after years with increased freshwater inflows, and they express concerns that water supply managers may mis-apply the results of Turner (Estuaries and Coasts 29:345–352, 2006) to justify a reduced freshwater inflow to Galveston Bay. I find no relationship between the CPUE of oyster spat or marketable oyster density and the commercial harvest, but do find a strong inverse relationship between harvest and river discharge in Galveston Bay. There are three possible factors that may explain why the annual variations in the fisheries-independent data are not coherent with the annual variations in commercial harvest: variable levels of water quality, inconsistent fishing effort, and the fact that the fisheries-independent data are not prorated for the area of the reefs actually fished. I concur, completely, with the apprehension that reductions in freshwater inflow will be implemented without examining the full set of assumptions and consequences, and thereby compromise estuarine ecosystem quality, and perhaps permanently, before mistakes can be seen or reversed.  相似文献   

A molecular dynamics study of natural organic matter: 1. Lignin, kerogen and soot     

Lu Zhang  Eugene J. LeBoeuf   《Organic Geochemistry》2009,40(11):1132-1142

Molecular dynamics (MD) simulations were performed on molecular models of a spectrum of natural organic matter (NOM) samples represented by two lignin samples (a softwood lignin and a hardwood lignin), a kerogen (Green River Shale kerogen) and a soot sample (n-hexane soot). Simulated thermodynamic properties of each model, including glass transition temperature (T_g), thermal expansion coefficient (α), density (ρ) and solubility parameter (δ) were compared against experimental data for corresponding samples. Results revealed relatively good agreement for glass transition temperature and solubility parameter for softwood lignin, Green River Shale kerogen and n-hexane soot models. An unexpectedly low solubility parameter for a hardwood lignin model suggests, however, certain model deficiencies in terms of intermolecular interactions. In addition, a lower density for a n-hexane soot model relative to the sample was attributed to the small cluster size and poor parallel stacking of aromatic clusters in the model. Discussion of the results is provided in the context of utilizing thermodynamic properties as constraints for improved structural modeling of NOM.  相似文献   

Salinity history of coastal marshes reconstructed from diatom remains     

Michael L. Parsons  Quay Dortch  R. Eugene Turner  Nancy N. Rabalais 《Estuaries and Coasts》1999,22(4):1078-1089

Sediment cores were collected from three Louisiana coastal marsh ponds, dated with radioisotopes, and analyzed for diatom remains to determine if long-term salinity changes were evident in the sediment record. A diatom-based salinity index formulated from a statistical comparison of available salinity data and changing diatom assemblages demonstrated that diatom remains appear to preserve salinity signals in coastal brackish and salt marsh environments. The salinity index was applied to sediment cores spanning the late 1600s to the 1990s and provided a more complete record of salinity than field data, which were temporally and spatially incomplete. The salinity reconstructions indicated that salinity has increased at two sites and decreased at a third since the early 1900s. The salinity changes are less than 1‰ per decade in all cases, and may be due to natural variability as depicted by the wide range of salinities observed between the late 1600s and 1900. Salinity regimes may be very localized (<2 km from a hydrologic source), indicating single-site studies may not be applicable to regional inferences. This study demonstrates that diatoms can be used to reconstruct past salinity in coastal marsh environments and can provide a useful tool with which to study the changing hydrology of river-influenced ecosystems.  相似文献   

Special Issue: IAMG 2019     

Leung  Juliana Y.  Li  Liangping  Morgan  Eugene  Emami-Meybodi  Hamid 《Mathematical Geosciences》2020,52(8):975-976

Mathematical Geosciences -  相似文献   

THE MILLS,NEW MEXICO,CHONDRITE — A NEW FIND     

G. R. Levi-Donati  Eugene Jarosewich 《Meteoritics & planetary science》1974,9(2):145-155

A mineralogical and chemical analysis has been performed on a slice of the Mills, New Mexico, chondrite, which was found in August 1970. The mineralogical composition is olivine Fa_19.5, bronzite, Fs_17.4, plagioclase, nickel-iron, troilite and ilmenite. The chemical analysis confirms that Mills is a typical bronzite, H5 chondrite, with considerable degree of weathering, as indicated by the presence of large amounts of Fe₂O₃. A comparison with other stones found in the same New Mexico region by Nininger may show a possible relation between Mills and previous finds.  相似文献