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1.
Spatial variation in soil inorganic nitrogen across an arid urban ecosystem   总被引:4,自引:1,他引:3  
We explored variations in inorganic soil nitrogen (N) concentrations across metropolitan Phoenix, Arizona, and the surrounding desert using a probability-based synoptic survey. Data were examined using spatial statistics on the entire region, as well as for the desert and urban sites separately. Concentrations of both NO3-N and NH4-N were markedly higher and more heterogeneous amongst urban compared to desert soils. Regional variation in soil NO3-N concentration was best explained by latitude, land use history, population density, along with percent cover of impervious surfaces and lawn, whereas soil NH4-N concentrations were related to only latitude and population density. Within the urban area, patterns in both soil NO3-N and NH4-N were best predicted by elevation, population density and type of irrigation in the surrounding neighborhood. Spatial autocorrelation of soil NO3-N concentrations explained 49% of variation among desert sites but was absent between urban sites. We suggest that inorganic soil N concentrations are controlled by a number of ‘local’ or ‘neighborhood’ human-related drivers in the city, rather than factors related to an urban-rural gradient.  相似文献   
2.
研究中国古代城市文学的文学史意义在于,从空间视角重新认识和研究古代文学,充分发掘和利用长期以来被忽略的城市文学资源。有助于建构起时空并置、更加完整和系统的中国古代文学史。此外,研究中国古代城市文学还可以为当代文学史研究提供一个广阔的历史视野与意蕴深厚的历史文本。  相似文献   
3.
The development of a Municipal Information System, or currently better known as a local spatial data infrastructure, is considered complex due to the required inter-institutional relationships. In many developing countries Geographical Information Systems (GISs) are introduced but the benefits are modest as no changes take place in technical and organisational structure of organisations. Digital databases and computer-aided design (CAD) maps are mushrooming in great variety within different private and public institutions, municipal organisations and even within single departments and with structures similar to the paper period and thus operating on a stand-alone basis.Many national mapping agencies are not able to provide large-scale digital urban base maps, while the absence or low quality of cadastres makes those basic core data sets unavailable or inaccessible. The result is that duplication and incompatible data are frequently observed and also donor-driven stand-alone projects have a limited impact through the lack of institutional embedding and are not able to mature from the project to the institutional level. However, a positive sign is that there is an increasing awareness among data producers and consumers that investments in the development of digital data sets should be combined to reduce costs and increase benefits from especially GIS, and information and communication technology (ICT) in general.Within Trujillo a long-term vision was developed to make full use of ICT and GIS to modernise all operations of the Municipality to increase the efficiency and effectiveness of its tasks. However, large investments are not feasible due to the very limited municipal budgets. To guarantee the support of the municipal council, short-term results are required. This paper describes three ‘products’ as part of the vision to develop through a step-by-step approach a local spatial data infrastructure for Trujillo.The three, rather different, products are:
1. fiscal cadastre, to increase municipal revenues through property taxation;
2. an ‘environmental atlas’ based on a compatible spatial and attribute data sets from a variety of organisations; and
3. a municipal website with interactive GIS and meta data information.
The paper concludes with some comments on the institutional and political requirements for the successful development of a local spatial data infrastructure and stresses that such an infrastructure is not a product but an incremental development process that will progress only in case such a process is simple, cost effective, user-friendly, and flexible with clear products.Political interest and institutional stability and genuine interest for inter-institutional cooperation will add much to the success of this process.  相似文献   
4.
In the modern western world, the discursive construction of fatherhood and everyday fathering practices has been underpinned by the spatial separation of work from home, of public from private. However, increasing numbers of employees are now working from home and a disproportionate number of these are men with young children. This article draws on new empirical research to examine the implications for fathers and for organizations as home‐working disrupts earlier spatial configurations of fatherhood and fathering practices. The article concludes that as the spatial boundaries between home and work collapse, new accommodations between fatherhood/fathering and organization are emerging. However, these are underpinned by a traditional gender division of labour in the household. More broadly, these findings confirm the inadequacy of static distinctions between public and private, showing that while such distinctions are still used to mark space and time, this is relational, contingent and unstable.  相似文献   
5.
我国各民族之间的差异、民族区域自治制度及其自治权的存在是我国区域刑事法律冲突产生的基本原因,而通过制定顾全大局、兼顾特别的变通性、补充性刑法规范,可缓解这一冲突;通过加快少数民族地区的发展步伐,逐步消除民族之间的政治、经济、文化上的差距,进而达到彻底消除这一冲突,实现法制统一的良好局面。  相似文献   
6.
The author presents a multivariate location model for cluster correlated observations. He proposes an affine‐invariant multivariate sign statistic for testing the value of the location parameter. His statistic is an adaptation of that proposed by Randles (2000). The author shows, under very mild conditions, that his test statistic is asymptotically distributed as a chi‐squared random variable under the null hypothesis. In particular, the test can be used for skewed populations. In the context of a general multivariate normal model, the author obtains values of his test's Pitman asymptotic efficiency relative to another test based on the overall average. He shows that there is an improvement in the relative performance of the new test as soon as intra‐cluster correlation is present Even in the univariate case, the new test can be very competitive for Gaussian data. Furthermore, the statistic is easy to compute, even for large dimensional data. The author shows through simulations that his test performs well compared to the average‐based test. He illustrates its use with real data.  相似文献   
7.
维语广告与维吾尔族风俗习惯存在碰撞和交融。一方面,维吾尔族风俗习惯对维语广告的表达具有潜移默化的作用,使之呈现出独特的审美意蕴;另一方面,维语广告对维吾尔族风俗习惯有着不容忽视的改变,展现并促进着它们由传统向现代转型。二者相辅相成,共同将维语广告的发展推向一个更成熟、更有效的境界。  相似文献   
8.
文学作品是作家本性、人格精神的复现。江西遗民词作为江西遗民词人群个性、心灵之诗意表现 ,其中所表露出的欲挽狂澜于既倒、重整乾坤的雄心与壮志、对自身归属感的积极寻求和对自己所处时空的理性反思、及对社会人生的执著与关注等内容 ,正是这个词人群体在江西独特的地域文化环境中生成的豪逸之气、忠义之心、耿直之性等群体特征的文学表达 ,具有鲜明的地域共性与特色。  相似文献   
9.
The authors consider the issue of map positional error, or the difference between location as represented in a spatial database (i.e., a map) and the corresponding unobservable true location. They propose a fully model‐based approach that incorporates aspects of the map registration process commonly performed by users of geographic informations systems, including rubber‐sheeting. They explain how estimates of positional error can be obtained, hence estimates of true location. They show that with multiple maps of varying accuracy along with ground truthing data, suitable model averaging offers a strategy for using all of the maps to learn about true location.  相似文献   
10.
This paper deals with techniques for obtaining random point samples from spatial databases. We seek random points from a continuous domain (usually 2) which satisfy a spatial predicate that is represented in the database as a collection of polygons. Several applications of spatial sampling (e.g. environmental monitoring, agronomy, forestry, etc) are described. Sampling problems are characterized in terms of two key parameters: coverage (selectivity), and expected stabbing number (overlap). We discuss two fundamental approaches to sampling with spatial predicates, depending on whether we sample first or evaluate the predicate first. The approaches are described in the context of both quadtrees and R-trees, detailing the sample first, acceptance/rejection tree, and partial area tree algorithms. A sequential algorithm, the one-pass spatial reservoir algorithm is also described. The relative performance of the various sampling algorithms is compared and choice of preferred algorithms is suggested. We conclude with a short discussion of possible extensions.  相似文献   
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