共查询到20条相似文献，搜索用时 484 毫秒
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Between 2000 and 2014, more than thirty geography departments adopted revised or new names, with some entirely dropping geography. Although renaming and rebranding efforts are not new to higher education, the rapid pace at which geography department names have changed raises questions about the discipline's identity and health. We examine the renaming trend within geography programs together with intended and unexpected factors as perceived by faculty. Specifically, we look at the renaming and rebranding trend within the context of four pillars offered by Pattison (1964) to define geography's principal academic domains—earth-science, man–land, area/regional studies, and spatial traditions. 相似文献
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Residential segregation in metropolitan areas has been the subject of much research, but this article analyzes patterns of white–black and white–Hispanic segregation in counties across the United States. Our purpose was to understand county variations in this one dimension of inequality. Conceiving of segregation as relative inequality of access to neighborhood resources, we measured segregation in 2000 by the index of dissimilarity (D) calculated by blocks, mapped the index values, and correlated them with census variables. Three filters enabled us to eliminate counties with characteristics that could have corrupted the analyses, leaving us with more than 1,000 counties in each analysis. Both minority groups were less segregated from whites in the West and South and in metropolitan counties. Lower segregation was strongly associated with higher minority socioeconomic status and higher percentages of minorities living in housing built in the 1990s, and Hispanic–white segregation was lower where more Hispanics were U.S.-born or English proficient. The racial threat hypothesis was supported only weakly and inconsistently. Mapping made it possible to identify regional and local patterns of high and low segregation as well as the lower segregation of suburban counties in some large metropolitan areas. 相似文献
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PAUL MATHER 《International journal of geographical information science》2013,27(2):258-259
As they increase in popularity, social media are regarded as important sources of information on geographical phenomena. Studies have also shown that people rely on social media to communicate during disasters and emergency situation, and that the exchanged messages can be used to get an insight into the situation. Spatial data mining techniques are one way to extract relevant information from social media. In this article, our aim is to contribute to this field by investigating how graph clustering can be applied to support the detection of geo-located communities in Twitter in disaster situations. For this purpose, we have enhanced the fast-greedy optimization of modularity (FGM) clustering algorithm with semantic similarity so that it can deal with the complex social graphs extracted from Twitter. Then, we have coupled the enhanced FGM with the varied density-based spatial clustering of applications with noise spatial clustering algorithm to obtain spatial clusters at different temporal snapshots. The method was experimented with a case study on typhoon Haiyan in the Philippines, and Twitter’s different interaction modes were compared to create the graph of users and to detect communities. The experiments show that communities that are relevant to identify areas where disaster-related incidents were reported can be extracted, and that the enhanced algorithm outperforms the generic one in this task. 相似文献
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An outline is given of the career and scientific and teaching activity of the outstanding geomorphologist, professor of Moscow State University S.S. Voskresenskii, who created new scientific directions in the study of topography. He is rightfully given credit for geographical investigations of Siberia and the Far East in the latter half of the 20th century. 相似文献
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Susan E. Hume 《The Professional geographer》2013,65(4):555-557
Research on small cities has begun to attract the attention of scholars who argue that contemporary urban scholarship, in its preoccupation with the largest and most advanced world-class cities, have largely ignored small to medium-sized cities. In China, although much attention has been paid to economically advanced urban centers, there actually has been a steady stream of work on small cities. This article profiles how a comparatively smaller city in western China attempts to market itself by selectively placing itself within various social–spatial and political–economic realities. Through Jinghong, we illustrate how local officials and planners attempt to center the city as a gateway to Southeast Asia. By activating, often discursively, multiscalar transborder strategies, local officials in Jinghong not only mobilize ethnic imaginaries, but they also adopt forms of entrepreneurial tactics to promote growth. Developmental strategies of Jinghong not only vacillate between (and draw on) both rural and urban resources; they are furthermore expected to alleviate rural poverty. Through highlighting the agency of small cities like Jinghong in China, this article speaks to the broader developmentalist critique of third- and fourth-world cities as an unfortunate footnote in global urban restructuring, often depicted as places of uniform marginalization and structural irrelevance. Indeed, by focusing on the geography of small cities and giving due attention to their size and proximity to rural spaces, case studies like Jinghong might yet point empathetically to different ways and imperatives of “being urban” where the weight that they carry can also be duly recognized. 相似文献
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Rivers and streams originating in the surrounding mountainous area are the major sources of salt in the Salinas Grandes basin (Córdoba, Argentina). These rivers infiltrate when they reach the sandflat or in the fringes of the mudflat, feeding springs which often form shallow lakes. Presently, the lakes are distant from the playa edge, thus allowing inflow waters to dissolve ancient (Pleistocene?) evaporite beds. In the sandflat environment, two dominant types of water have been recognized (SO 4 2? -Cl?-HCO 3 ? -Na+, and Cl?-SO 4 2? -HCO 3 2? -Na+), both considered as original members of the brine in the saline complex. Two main sources of solutes were distinguished, one related to the waters supplied by the southern sector and another to waters of the eastern sector. As a result of the chemical evolution in the playa environment, all brines belong to the neutral type (Cl?-SO 4 2? -Na+). Following Hardie and Eugster's (1970) model, waters from the southern sector should evolve towards an alkaline brine (Cl?-SO 4 2? -HCO 3 ? -Na+), whereas those from to the eastern sector should evolve towards a neutral one (Cl?-SO 4 2? -Na+). A computer simulation was carried out to model the chemical evolution of source waters. The results obtained by this methodology showed the same dichotomy (alkaline vs. neutral) established by Hardie and Eugster's (1970) model. The deficit in alkalinity could not be explained by any of the mechanisms published until now. Gypsum dissolution is the most likely mechanism which accounts for the chemical evolution of the waters investigated. When such a process is included in the computations, the Ca2+ supplied by gypsum beds generates an increase in the ion activity product (aCa+2·aCO 3 2? ) and produces a significant change in the 2Ca+2/(2CO 3 2? +HCO 3 ? ) ratio, switching from values less than 1 to values greater than 1. This process determines the precipitation of calcite, and leads to a decrease in alkalinity, which in turn would explain the existence of a neutral brine in the saline complex. An intermediate salinity brine was detected in the mudflat, which, according to the model (Hardie and Eugster, 1970), should evolve towards a SO 4 2? -free neutral brine (Cl?-Na+-Ca2+). The absence of this type of brine may be explained through mixing processes. 相似文献
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Hongya Wang Hongyan Liu Yanhua Liu Haiting Cui Niels Abrahamsen 《Journal of Paleolimnology》2010,43(2):345-367
The Qinling Mountain Range (33°–34°30′N, 107°–111°E; 3,767 m a.s.l.) lies south of the Chinese Loess Plateau and functions
as the boundary between ‘north’ and ‘south’ China. Taibai Mountain (33°41′–34°10′N, 107°19′–107°58′E; 3,767 m a.s.l.) is the
central massif and highest part of the range and is the highest mountain in eastern and central China, east of 105°E. It is
also one of two mountains higher than the modern climatic timberline and the only one where high alpine lakes (>2,500 m a.s.l.)
exist in eastern and central China. Sediments were recovered from Foye Chi (33°57′N, 107°44′E; 3,410 m a.s.l.), a small lake
on the southern slope of the mountain, and measured for magnetic properties. Chronological control was achieved with AMS 14C dating. Combined with analyses of particle-size, TOC, C/N, δ13Corg and pollen in these sediments, and magnetic properties of catchment soils, the mineral-magnetic data reveal late Holocene
palaeoenvironmental changes on the high-altitude southern slope of Taibai Mountain. Climate gradually ameliorated about 2,300 cal yr BP
and warm and wet conditions occurred afterwards, culminating from 1,700 to 1,510 cal yr BP. The climate began to deteriorate
at 1,510 cal yr BP, but was still warmer and wetter than present until ~663 cal yr BP. Cool, arid conditions peaked and were
cooler and drier than the present at 663–290 cal yr BP, coincident with the Little Ice Age. Climate became warmer and more
humid again after 290 cal yr BP. Data from these less anthropologically-disturbed alpine-lake sediments provide a record of
late Holocene palaeoenvironmental change that supplements information from historical documents and literature for eastern
and central China. 相似文献