Reflections on Nigel Thrift's optimism: political strategies to implement his vision     

Ron Johnston   《Geoforum》2002,33(4):421-425

This response to Nigel Thrift's recent paper (2002, Geoforum 33, 291–298) develops two of his points: the need for geography to remain buoyant within school curricula and a potential split of physical from human geography within the universities. I argue that political strategies are necessary for both if geography is to remain the large, intellectually vibrant discipline that Thrift identifies.  相似文献   

Ethnic Residential Segregation Across an Urban System: The Maori in New Zealand, 1991–2001     

Ron Johnston  Michael Poulsen  James Forrest 《The Professional geographer》2005,57(1):115-129

In New Zealand there are substantial variations across the urban system in the degree of residential segregation of those claiming Maori ethnicity. Analyses of those variations, using measures particularly relevant to comparative study, show that Maori segregation was greatest in both 1991 and 2001 in larger urban areas and, especially, in those with relatively large Maori populations. A major deviation from this general pattern was in Auckland; further analysis suggests that this was because of considerable sharing of residential space involving Maori and Pacific Islanders. If the total population claiming a Polynesian identity is studied, the relationships between segregation and both size and Polynesian population share are clarified.  相似文献   

X线和CT对原发支气管癌的诊断价值     

高艳  古晓泉 《CT理论与应用研究》1994,3(1):17-20

本文利用Ｘ线、ＣＴ扫描技术，对原发支气管瘤的各种组织类型在Ｘ线及ＣＴ中的表现进行了观察，分析了其位置、大小、边缘、钙化、空洞和转移情况，阐明了胸部ＣＴ是肺癌时诊断肺门和纵隔侵犯的更佳方法，较Ｘ线有很大优越性。Ｘ线和ＣＴ相结合对原发支气管癌的定性诊断具有重要价值。  相似文献   

The intermediate-wavelength magnetic anomaly maps of the North Atlantic Ocean derived from satellite and shipborne data     

Jafar Arkani-Hamed  Jacob Verhoef  Walter Roest  Ron Macnab 《Geophysical Journal International》1995,123(3):727-743

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Modern and post-modern cities and ethnic residential segregation: Is Los Angeles different?   总被引：1，自引：0，他引：1  

Ron Johnston  Michael Poulsen 《Geoforum》2006,37(3):318-330

Dear and others associated with the ‘Los Angeles School of Urbanism’ have presented a series of challenging ideas regarding changes in urban form as a consequence of the shift from modernism to post-modernism. Some of those challenges relate to a city’s ethnic diversity and residential segregation, with Los Angeles presented as a paradigm exemplar of an emerging new urban form. This paper evaluates the arguments that Los Angeles in particular, and Californian metropolitan areas more generally, differ from metropolitan areas elsewhere in the United States in the nature of ethnic residential segregation there. Regression analyses provide little support for the argument, but graphical analyses show that although Los Angeles does not differ from the general, US-wide trends, its almost unique nature in terms of its ethnic diversity means that it clearly stands out as a place with a different pattern shared by very few others.  相似文献   

Short Note: On the Relativistic Doppler Effect for Precise Velocity Determination using GPS     

Jason Zhang  Kefei Zhang  Ron Grenfell  Rod Deakin 《Journal of Geodesy》2006,80(2):104-110

The Doppler effect is the apparent shift in frequency of an electromagnetic signal that is received by an observer moving relative to the source of the signal. The Doppler frequency shift relates directly to the relative speed between the receiver and the transmitter, and has thus been widely used in velocity determination. A GPS receiver-satellite pair is in the Earth’s gravity field and GPS signals travel at the speed of light, hence both Einstein’s special and general relativity theories apply. This paper establishes the relationship between a Doppler shift and a user’s ground velocity by taking both the special and general relativistic effects into consideration. A unified Doppler shift model is developed, which accommodates both the classical Doppler effect and the relativistic Doppler effect under special and general relativities. By identifying the relativistic correction terms in the model, a highly accurate GPS Doppler shift observation equation is presented. It is demonstrated that in the GPS “frequency” or “velocity” domain, the relativistic effect from satellite motion changes the receiver-satellite line-of-sight direction, and the measured Doppler shift has correction terms due to the relativistic effects of the receiver potential difference from the geoid, the orbit eccentricity, and the rotation of the Earth.  相似文献   

A coarse-grained basin floor turbidite system – the Jurassic Los Molles Formation,Neuquen Basin,Argentina     

Gabriel Giacomone  Cornel Olariu  Ron Steel  Moonsoo Shin 《Sedimentology》2020,67(7):3809-3843

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Differential developmental toxicity of naphthoic acid isomers in medaka (Oryzias latipes) embryos     

Carney MW  Erwin K  Hardman R  Yuen B  Volz DC  Hinton DE  Kullman SW 《Marine pollution bulletin》2008,57(6-12):255-266

Polycyclic aromatic hydrocarbons (PAHs) are widespread persistent pollutants that readily undergo biotic and abiotic conversion to numerous transformation products in rivers, lakes and estuarine sediments. Here we characterize the developmental toxicity of four PAH transformation products each structural isomers of hydroxynaphthoic acid: 1H2NA, 2H1NA, 2H3NA, and 6H2NA. Medaka fish (Oryzias latipes) embryos and eleutheroembryos were used to determine toxicity. A 96-well micro-plate format was used to establish a robust, statistically significant platform for assessment of early life stages. Individual naphthoic acid isomers demonstrated a rank order of toxicity with 1H2NA>2H1NA>2H3NA>6H2NA being more toxic. Abnormalities of circulatory system were most pronounced including pericardial edema and tube heart. To determine if HNA isomers were AhR ligands, spatial-temporal expression and activity of CYP1A was measured via in vivo EROD assessments. qPCR measurement of CYP1A induction proved different between isomers dosed at respective concentrations affecting 50% of exposed individuals (EC50s). In vitro, all ANH isomers transactivated mouse AhR using a medaka CYP1A promoter specific reporter assay. Circulatory abnormalities followed P450 induction and response was consistent with PAH toxicity. A 96-well micro-plates proved suitable as exposure chambers and provided statistically sound evaluations as well as efficient toxicity screens. Our results demonstrate the use of medaka embryos for toxicity analysis thereby achieving REACH objectives for the reduction of adult animal testing in toxicity evaluations.  相似文献   

A Comparison Between GEBCO Sheet 5.17 and the International Bathymetric Chart of the Arctic Ocean (IBCAO) Version 1.0     

Martin Jakobsson  Ron Macnab 《Marine Geophysical Researches》2006,27(1):35-48

In 1979, the General Bathymetric Chart of the Oceans (GEBCO) published Sheet 5.17 in the Fifth Edition of its series of global bathymetric maps. Sheet 5.17 covered the northern polar region above 64° N, and was for long the authoritative portrayal of Arctic bathymetry. The GEBCO compilation team had access to an extremely sparse sounding database from the central Arctic Ocean, due to the difficulty of mapping in this permanently ice covered region. In the past decade, there has been a substantial increase in the database of central Arctic Ocean bathymetry, due to the declassification of sounding data collected by US and British Navy nuclear submarines, and to the capability of modern icebreakers to measure ocean depths in heavy ice conditions. From these data sets, evidence has mounted to indicate that many of the smaller (and some larger) bathymetric features of Sheet 5.17 were poorly or wrongly defined. Within the framework of the project to construct the International Bathymetric Chart of the Arctic Ocean (IBCAO), all available historic and modern data sets were compiled to create a digital bathymetric model. In this paper, we compare both generally and in detail the contents of GEBCO Sheet 5.17 and version 1.0 of IBCAO, two bathymetric portrayals that were created more than 20 years apart. The results should be helpful in the analysis and assessment of previously published studies that were based on GEBCO Sheet 5.17. Ron Macnab: Retired.  相似文献   

Constituency election campaigning under the alternative vote: the New South Wales Legislative Assembly election 1995     

Ron Johnston  James Forrest 《Area》2000,32(1):107-117

Summary Most studies of the impact of local campaigning on the geography of election results in single-member constituency electoral systems have been conducted in countries where the 'first-past-the-post' system is employed. Australia uses the 'alternative vote' (AV) system for elections to the federal and some state Lower Houses, with parties competing for both first- and lower-preference votes. This paper analyses the relationship between spending and success in the contests for both types of votes at the 1995 New South Wales State Legislative Assembly election, with significant findings: the more intense a party's campaign, ceteris paribus, the more first-preference votes it obtained and the more lower-preference votess when these were reallocated. The AV system was recommended for adoption in the UK by a government-commissioned report in 1998, and the paper draws some implications for the UK situation.  相似文献