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ABSTRACT. We determine the location equilibria in a duopoly model under a novel solution concept. Typically, spatial equilibrium is described as either a simultaneous price and location game, or else as a two-stage location-then-price game. We introduce a new alternative, a two-stage price-then-location game. It is well known that no (pure strategy) equilibrium usually exists under the two standard solution concepts when products are homogeneous. We show this is also true for the new concept. We then provide numerical results for a specific functional form (the logit model) which introduces product heterogeneity into the standard framework, restoring equilibrium when the degree of substitutability between products is not too small.  相似文献   
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ABSTRACT. We reexamine the price structures and their welfare implications in three pricing regimes (mill, uniform and discriminatory) for a monopoly. We show that spatial price discrimination could provide the highest social welfare and, when consumers tastes are heterogeneous enough, also the highest consumer surplus. The superiority of spatial price discrimination is partially due to the larger output produced and partially due to differential treatment for consumers with heterogeneous tastes.  相似文献   
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The aim of this paper is to present the rich set of finds collected inside the grave Dibba 76/1, in the Emirate of Fujairah, during a season of rescue excavation conducted under the direction of S. Ali Hassan in 1994. The recovered grave‐goods include pottery, soft‐stone vessels, metal finds, personal ornaments, coins, and other items. Although comparable with other corpuses of material excavated in south‐eastern Arabia, the material of Dibba 76/1 stands out for the inner variety of the different artefacts’ classes and their remarkable chronological heterogeneity. The study of the grave‐goods suggests that Dibba 76/1 was reused over several centuries, showing a strong continuity in the funerary destination of this specific place from the end of the Wadi Suq period (2000–1600 BC) to the first phases of the late pre‐Islamic period (250 BC–AD 400), and the full integration of the area of Dibba in the succession of the various cultural facies known during this long time span.  相似文献   
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ABSTRACT

The structural analysis of a mirror-type vault, consisting of a single- or double-curvature perimeter and a nearly flat part, is carried out. The vault is similar to a number of hybrid iron (or steel) and masonry vaults built between the late 19th century and the early 20th century to span large halls. The numerical analyses were preceded by an accurate geometrical survey and mechanical tests aimed at evaluating the properties of the materials. Thermography allowed the complex brick pattern of the vault to be detected. The influence of rib-walls (frenelli) and the material anisotropy on the stress and deformation of the vault is discussed. Eventually, attention is focused on one of the segmental vaults in the central part of the structure: it is found that the stress can be safely estimated by assuming its boundary to be fixed.  相似文献   
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ABSTRACT

The concept of topoiesis of textual space addresses an analysis of the spatial elements that tend to provide a meaning to the literary text. Based on textual semiotics where there is an organized relational system of meanings, in this article we propose that it is possible to determine the function of space as a meaning issue from three different literary text instances (event or motive; character; and object). This distinction will permit a deeper interpretation of the sense of space in the literary text.  相似文献   
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A multiproxy approach based on archaeobotanical, organic residue and isotopic analyses was carried out on materials from 12 Medieval archaeological sites in Tuscany (central Italy), in order to provide a diachronic overview of local diet in rural and urban sites from the mid-eighth to the fourteenth centuries AD. Archaeobotanical analyses were applied to 130,578 seeds/fruits, residue analyses involved 87 samples from cooking and storing vessels, whereas analyses of carbon and nitrogen stable isotopes included 63 human bone samples and 26 animal specimens. The results indicate that from the mid-eighth century AD, crop production was of high quality similar, to that of the Roman Age. The main cultivations were naked wheats, barley and horse bean, a diversity that attests the technological skills reached by Tuscan peasants during the whole Middle Ages. Different cereals and pulse abundantly supplemented the diet. This strategy not only ensured peasants’ subsistence in the mid-eighth century AD, minimizing the risks of environmental adversities, but it also increased crop production – from the mid-ninth century AD on, for the revived markets and trade. Between the eleventh and fourteenth centuries AD, C4 plants had a dominant role in the peasants’ diet, when the wheat production was strictly collected first by the landlords and then by the cities for their own needs. Crop production was integrated by swine farming; animal meat consumption is well documented in rural and urban populations from the ninth century AD. Wine and olive oil, considered important elements of diet in Medieval Tuscany, have a very scarce presence, but they are recorded for later periods, mainly in urban areas and in higher social classes, such as the religious and aristocratic ones. In fact, only between the twelfth and thirteenth centuries AD was the great expansion of olive groves and vineyards recorded, when cities and urban populations claim to have access to these luxury foods.  相似文献   
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Radon (Rn) is a potentially toxic gas in soil which may affect human health. Assessing Rn levels in soil gas usually requires enormous efforts in terms of time and costs, since the sampling protocol is very complex. In most cases, the variable under study is sparsely sampled over the domain and this could affect the reliability of the spatial predictions. For this reason, it is useful to incorporate, into the estimation procedure, some auxiliary variables, correlated with the in soil gas Rn concentrations (primary variable) and more densely available over the domain. On the basis of this latter aspect, it is even better if the covariates are derived from a geographical information system (GIS). In this article, the Rn sampling protocol used during a measurement campaign planned over a risk area is described and the process of deriving GIS covariates considered as secondary information for predicting the primary variable is clarified. Then, multivariate modeling and prediction of the Rn concentrations over the domain of interest are discussed and a comparative study regarding the performance of the prediction procedures is presented. Rn prone areas are also analyzed with respect to urban and school density. All these aspects can clearly support decisions on environmental and human safeguard.  相似文献   
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Abstract: This paper examines an apparent anomaly that lies at the heart of processes of financial exclusion within Britain. Given that the branch networks of banks and building societies have shrunk in size by about one‐third since 1989, a period during which the Government has launched a wide‐ranging set of policies to tackle financial exclusion, why is it that the issue of branch closure has been neutralised as a political issue? After providing evidence to show the extent of branch closure in Britain and illustrating the ways in which geographical research in particular has drawn attention to the nature of this problem, we look at the way the issue of physical access to financial services has been discursively and politically marginalised. We undertake a detailed history of public policy in the area, and the ways in which research funded by industry bodies and Government departments has been used and framed to build a pro‐market, neoliberal policy programme that constructs branch closures as natural and inevitable.  相似文献   
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