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排序方式: 共有321条查询结果,搜索用时 15 毫秒
11.
This study examined landcover change during 1940–1988 in two contiguous landscapes of approximately 12,400 hectares in central Ohio, USA: an inertial till plain area and a more dynamic moraine area. Agriculture dominated both landscapes throughout, however, the cover of natural vegetation and urban-suburban development increased over time on the moraine while natural vegetation decreased and agriculture increased on the till plain. Markov process models for landcover change were constructed for three 14–17-year time intervals and for the entire forty-eight-year study period. Probabilities of self-replacement for agricultural lands (0.91–0.97) were higher and those for forests (0.54–0.65) lower than those reported for other landscapes. Predictions of landcover percentages for fifty years in the future were made using Markov process models derived from actual cover changes in 1940–1957, 1971–1988, and 1940–1988. All three models produced similar predictions for the inertial till plain area. In contrast, the three models' predictions differed considerably for the moraine area. Only the 1971–1988 transition matrix was sensitive to increases in urbanization and reforestation which began on the moraine in the 1970s. These results indicate that reliance on lengthy study intervals and net rates of change can obscure spatial and temporal patterns of landcover change that are caused by natural and socioeconomic factors operating on shorter time scales.  相似文献   
12.
This article presents a Bayesian method based on spatial filtering to estimate hedonic models for dwelling prices with geographically varying coefficients. A Bayesian Adaptive Sampling algorithm for variable selection is used, which makes it possible to select the most appropriate filters for each hedonic coefficient. This approach explores the model space more systematically and takes into account the uncertainty associated with model estimation and selection processes. The methodology is illustrated with an application for the real estate market in the Spanish city of Zaragoza and with simulated data. In addition, an exhaustive comparison study with a set of alternatives strategies used in the literature is carried out. Our results show that the proposed Bayesian procedures are competitive in terms of prediction; more accurate results are obtained in the estimation of the regression coefficients of the model, and the multicollinearity problems associated with the estimation of the regression coefficients are solved.  相似文献   
13.
The period comprising the end of the Early Neolithic and the Middle Neolithic, dated broadly within the fifth millennium cal BC, corresponds to an interval that remains largely unknown in the extreme north-western tip of Africa. This situation contrasts with that of the Early Neolithic, a period characterised by the earliest evidence of the diffusion of a productive economy, cultivated plants and domestic animals. The paucity of data for these later phases can be explained in part by the lack of secure contexts and sequences based on radiocarbon datings of short-lived samples. The current study presents the results of the excavations of El-Khil Caves B and C that yield materials allowing re-evaluation of the chronology of a type of ceramic known as Ashakar ware. The study also identifies two traditions in the northern Moroccan Middle Neolithic. The first is heir to the so-called Impressa Mediterranean ware and rooted in the Cardial Neolithic, while the second is characterised by roulette cord impressions, red slip and tunnel lugs and probably rooted in the region of the Sahara, and has no technological precedents in the study area.  相似文献   
14.
Most quantitative approaches to distributional analysis in archaeology assume a homogeneous study surface that is amenable to easy generalisations. This framework has been widely used to describe settlement processes, disregarding the spatial heterogeneity inherent to geographic reality. In other words, researchers have often assumed that the correlation between the elements of a spatial distribution is a function of the Euclidean distance (i.e. straight line distance) between them. Other archaeological studies have tested alternative measures to Euclidean distances, such as cost-based ones, both to describe optimal routes and to assess spatial autocorrelation in a point pattern. Nevertheless, until now there has been no suitable model to introduce these measures into spatial statistical equations. In order to overcome this obstacle, we approach the implementation problem inversely by embedding the spatial pattern under study into a Euclidean frame of reference based on its cost-distance pairwise matrix. This paper describes the application of this methodology on one of the main tools used by archaeologists to assess settlement patterns: Ripley’s K function. We present two case studies, covering both macroscale and mesoscale, with significant variations in the results depending on the use of the Euclidean or cost-based approach. Data, functions and results have been R-packaged for the sake of reproducibility and reusability, allowing other researchers to build upon our methods.  相似文献   
15.
The aim of this work is to characterize the original concrete from Roman buildings for public spectacles, theatre and amphitheatre, from Emerita Augusta, Mérida, Spain. An advanced knowledge of the Roman concrete composition is required for a reliable restoration and preservation of these ancient monuments. The concrete was studied through mineralogical (optical polarized microscopy and X-ray diffraction) and petrophysical (bulk and real density, open porosity to water and Hg, mechanical strength and ultrasonic velocity) analyses. With this work, it is possible to fill the gap that exists in this field and the characterization of the materials used in the Roman concrete from these two buildings, never previously studied, despite the significance of this archaeological ensemble, declared a World Heritage Site by UNESCO in 1993. The results allowed us to determine the composition of the Roman concrete and to infer the provenance of the aggregates used in these monuments.  相似文献   
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This article analyzes the novels Muertes paralelas and Ayer no más as representatives of two clearly defined perspectives within the Spanish twenty-first century narrative production on unearthing the past of Francoism. The symbolic construction of unearthing permits an investigation of the remnants of a neo-Francoist vision of the legacy of the civil war, while opening the view of a political feeling by which personal memory inserts itself most profoundly as a commitment to a more comprehensive and lasting closure of the past.  相似文献   
18.
This article breaks new ground in examining how “new Irish” immigrant women have responded to the collapse of Ireland’s Celtic Tiger economy and the different forms of gender discrimination and marginalisation they face both within their minority ethnic communities and the Irish host society. It approaches Ebun Akpoveta’s Trapped: Prison Without Walls (2013) as an exemplary work of fiction which exposes unresolved injustices and inequalities suffered by immigrant women. Akpoveta creates a narrative that complicates previous representations of cultural encounters between newcomers and long-established members of Ireland’s host society, not least because her Nigerian female protagonist arrives as a postgraduate student rather than an asylum seeker or refugee. She fictionalises female experiences of marginalisation, gender-based violence and family dysfunction within an all-Nigerian family that outwardly appears to be a model of integration and social inclusion in an open and welcoming Irish multicultural society.  相似文献   
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The benefits of urban open spaces for improving the quality of life and sustainability in cities are widely recognized. The functions they perform within the framework established by urban planning, as well as their metrics, are now more complex than in the past. It is convenient to develop methodologies for the evaluation of these spaces adapted to the present time to check their level of efficiency, which is useful in urban planning for the establishment of new urban open spaces. The aim of this study is to classify such spaces through a methodology that integrates spatial analysis, configuration analysis, and decision support so as to understand their complexity from a more advanced analytical perspective. In order to do this, a prior exploration of specific literature is carried out, which allows the characterization of the functions of urban open spaces by means of the corresponding analysis variables in a weighted manner. The integrated combination of these advanced tools is a step forward in achieving consistent and detailed results for urban open spaces. They perform their functions best in dense, central, equipped, accessible, connected, and easily walkable urban environments. In addition, future recommendations are provided.  相似文献   
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