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41.
    
Agglomeration economies explain why productivity increases as the size of agglomeration increases, and thereby partly explain the importance of location and space in economic development. Agglomeration economies are based on the distance between firms, labour and the market. Infrastructure investment can be a tool used by governments to affect this distance, where, in doing so, they induce agglomeration economies and increase economic growth. In this paper, we will discuss the importance of considering types of networks when analysing agglomeration economies using multiregional new economic geography (NEG)‐based spatial general equilibrium models. These models typically use abstract bi‐regional origin‐destination networks to describe the cost of transporting or commuting between regions. These abstract networks are like tunnels between regions and do not take into account the actual roads in real infrastructure networks used for transport and traffic between destinations. In other words, in real infrastructure networks, which we label full networks, people and goods move from one region to another via actual roads and possibly via third regions. In the empirical economic literature, there is a significant difference between the economic effect of changes in a bi‐regional origin‐destination network and the economic effect of changes in a full network. To date, no systematic explanation has been given for this difference in the size of the effects. Lack of an explanation for this difference may lead to confusion among policy‐makers who have to decide on infrastructure investment. In this methodological paper, we discuss the reason for this difference. We do not discuss the absolute size of the agglomeration effects, only the relative difference that exists when using different types of networks. In order to explain the difference, we introduce a methodology that translates the effects in a bi‐regional origin‐destination network into similar effects in a full network, making it possible to systematically compare the economic importance of all links (roads) in such a network. This is highly relevant to policy‐makers, who can now interpret the model results on a real full infrastructure network. We will also show the mathematical relationship between the importance of agglomeration economies on a link in a full network and the importance of agglomeration economies on a link in a bi‐regional origin‐destination network. Finally, the methodology is illustrated with a case study from the Netherlands.  相似文献   
42.
    
Numerical site response analyses were carried out on the Nicastro ridge in Southern Italy in order to investigate topographic effects. First, the analyses were carried out on a simplified model by employing simple artificial signals, in order to get preliminary physical insights into the two-dimensional phenomena involved. Then, numerical analyses were carried out on a more realistic heterogeneous subsoil model developed on the basis of geotechnical and geophysical investigations. Real accelerograms were selected for these analyses. Particular attention was devoted to separating topographic from stratigraphic amplification. Finally, the topographic amplification factors were compared with literature data and Eurocode 8 recommendations.  相似文献   
43.
    
ABSTRACT This paper investigates the extent to which house–price uncertainty affects the transition of renter households into homeownership. Using a 14‐year household panel from the Panel Study of Income Dynamics during the years 1984–1997 and measures of the time‐varying risk and return to owner‐occupied housing, we estimate a Cox proportional hazard model of the effect of house–price volatility on the transition into homeownership. Results indicate that house–price uncertainty has a negative and dramatic impact on transitions into homeownership. In addition, we find that the low‐wealth renters are particularly sensitive to house–price risk.  相似文献   
44.
    
We use a non‐site survey methodology and statistical significance testing to evaluate Hall's (1992a) predictive model of stone artefact distributions in the south‐east Australian highlands. The study area is a 19.5 km2 rectangular corridor in the Limestone Creek valley, north‐east Victoria. The study confirms a number of Hall's predictions about the relationship between stone artefact density and environmental factors. The strongest relationship is between artefact density and slope. This relationship is probably a reflection of both cultural and non‐cultural processes, which have promoted higher artefact density on the more subdued terrain. We also found that less common artefact types such as retouched tools and cores had the least predictable spatial distributions, although this may be a reflection of the small sample size.  相似文献   
45.
    
The agricultural sector in the Netherlands has lost much of its importance over the last 50 years in terms of the number of people involved and its relative contribution to the economy – even though production is still increasing. Yet, the area under agricultural use has changed relatively little: farmland still dominates the country. The question for the future is how expected further changes in agriculture will affect agricultural land use: how much land will be taken out of production and to what use it will be put. This is especially relevant now that the Dutch Government has decided to loosen its grip on spatial planning. Two opposing socio‐economic scenarios are therefore drafted that offer a coherent view on agricultural change, external pressures and government intervention. Implementing these in a land use simulation model provides an initial answer to the possible future of agricultural land in the country.  相似文献   
46.
    
This study uses data of about 9,000 apartment sales in Stockholm, Sweden, to assess the impact of crime on property prices. The study employs hedonic pricing modelling to estimate the impact of crime controlling for other factors (property and neighbourhood characteristics). Geographic Information System (GIS) is used to combine apartment sales by coordinates with offences, land use characteristics and demographic data of the population. The novelty of this research is threefold. First, it explores a set of land use attributes created by spatial techniques in GIS in combination with detailed geographical data in hedonic pricing modelling. Second, the effect of crime in neighbouring zones at one place can be measured by incorporating spatial lagged variables of offence rates into the model. Third, the study provides evidence of the impact of crime on housing prices in a capital city of a traditional welfare state, information otherwise lacking in the international literature. Our results indicate that apartment prices in a specific area are strongly affected by crime in its neighbouring zones, regardless of crime type. When offences were broken down by types, residential burglary, theft, vandalism, assault and robbery individually had a significant negative effect on property values. However, for residential burglary such an effect is not homogenous across space, and apartment prices in central areas are often less discounted by being exposed to crime than those in the city's outskirts.  相似文献   
47.
    
An integrated, multi‐analytical approach combining the high sensitivity of SR‐μXRF, the light element capability of PIXE/PIGE under a helium flux and the spatial resolution of BSEM + EDS was used to characterize chemical composition and corrosion of glass samples (first to fourth centuries ad ) from an important, but scarcely investigated, Roman region of south‐west Iberia (southern Portugal). The geochemical trends and associations of major, minor and trace elements were investigated to shed light on production techniques, the provenance of raw materials and decay mechanisms. The results, while confirming a production technique common to Roman glasses throughout the Empire—that is, a silica‐soda‐lime low‐Mg, low‐K composition, with glass additives as colouring and/or decolouring agents (Fe, Cu, Mn, Sb)—show at one site high Zr–Ti contents, suggesting a more precise dating for these glasses to the second half of the fourth century. The Ti–Fe–Zr–Nb geochemical correlations in the pristine glass indicate the presence of minerals such as ilmenite, zircon, Ti‐rich Fe oxides and columbite in the sands used as raw materials for the glass former: these minerals are typical of granitic‐type source rocks. The unusually high K content in the corrosion layers is consistent with burial conditions in K‐rich soils derived from the alteration of 2:1 clays in K‐bearing rock sequences.  相似文献   
48.
    
A quantitative bioenvironmental study of cranioskeletal size has been made of a latitude-ordered sequence of 14 series of adult skeleton sets (N=305): the archaeological remains of aboriginal maritime peoples inhabiting the west coast of North America between southern California and the Arctic. Of eight osteometric parameters of cranioskeletal size developed, the most important are partial skeleton volume (PSK) and cranial capacity (CC); and the principal bone-affecting environmental factors are the northerly climate (CLIM2c), the reconstructed diet deficient in calcium and overabundant in animal foods and vitamin D (DIET3c), and demographic stress (DSg). Prior research has demonstrated that cranioskeletal size increases with geographical latitude and decreases under dietary calcioprivation and unphysiologically high birth rates. Upon linear multifactorial statistical analysis our main finding, limited to the Amerindian subsequence (n=11 series) from the Santa Barbara Channel, the San Francisco Bay Region and the Northwest Coast, is that PSK and CC vary in direct proportion to CLIM2c, and inversely with DIET3c and DSg. Controlling for the latter two osteoantitrophic factors, coastal Amerindian female PSK rises by 9% between 34 and 54°N latitude, CC by 5%; and the male incremental rates are somewhat higher, 13 and 10%, respectively. This newly discovered climate-dependent race cline, an example of Bergmann's Rule, is interpreted as factual evidence of a mid-Wisconsin or earlier arrival date for the first Palaeoindians. Cranioskeletal size of the very small (n=3 series) Western Eskimo subsequence approximates the northernmost values of the coastal Amerindian distribution. © 1998 John Wiley & Sons, Ltd.  相似文献   
49.
    
The simulation of Sea-ice in a coarse resolution ocean general circulation model is examined in Hudson Bay and surrounding waters. Sea-ice distribution and duration compared well to climatological values, although ice thickness is undersimulated as it is in other modelling work. In Hudson Bay ice thickness variation was dominated by the atmospheric forcing as shown by the symmetric response of ice thickness to warming and cooling scenarios. Below ice heat fluxes play a more significant role in Foxe Basin and Baffin Bay where they mitigate air-ice heat loss by as much as 40 percent, thus limiting ice thickness and duration. Below ice heat flux reduces by 23 percent for the region of study (Hudson Bay, Foxe Basin, Baffin Bay, and Labrador Sea) for a global 3°C cooling and increases by 9 percent for a 3°C global warming. This asymmetric response is attributed to the ocean's asymmetric response to warming and cooling scenarios. In so much as Hudson Bay is dominated by atmospheric forcing rather than under ice heat as these results indicate, coarse resolution models may be useful in assessing the impact of change. However the necessary reconfiguration of the model grid render results from Foxe Basin and Hudson Strait less credible. On étudie la simulation de glace marine dans un modèle de circulation océanique générale à faible résolution dans la baie d'Hudson et dans les eaux avoisinantes. La distribution et la durée de la glace marine correspondent bien aux valeurs climatologiques, bien que l'épaisseur de la glace soit sous-simulée comme c'est le cas dans d'autres travaux de modélisation. Dans la baie d'Hudson, la variation de l'epaisseur de la glace est dominée par le forçage atmosphérique, comme on peut le voir d'après la réponse symétrique de l'épaisseur de la glace suivant les scénarios de réchauffement et de refroidissement. Les flux de chaleur sous la glace jouent un rôle plus important dans le bassin de Foxe et la baie Baffin, où ils permettent une réduction des pertes de chaleur air-glace allant jusqu'à 40 pour cent, limitant ainsi l'épaisseur de la glace et la durée. Le flux de chaleur sous la glace diminue de 23 pour cent dans la région étudiée (baie d'Hudson, bassin de Foxe, baie Baffin et mer du Labrador) pour un refroidissement global de 3C et augmente de 9 pour cent pour un réchauffement global de 3C. On attribue cette réponse asymétrique à la réponse asymétrique de l'océan aux scénarios de refroidissement et de réchauffement. Dans la mesure où, comme l'indiquent ces résultats, la baie d'Hudson est dominée par le forçage atmosphérique plutôt que par la chaleur sous la glace, des modèles à faible résolution peuvent être utiles pour évaluer l'impact des changements. Cependant, la reconfiguration nécessaire de la grille du modèle atténue la crédibilité des résultats obtenus dans le Bassin de Foxe et le détroit d'Hudson.  相似文献   
50.
3S技术在遗址探查中的应用   总被引：1，自引：0，他引：1  
常规遗址探查方法,普查难度大,影像上不能直接识别小型遗址.为此,应用3S技术(遥感技术(RS)、全球定位系统(GPS)、地理信息系统(GIS))在遗址探查中的作用和优势,提出了基于地物空间关系知识、多源信息复合探查的思路.应用结果以巢湖柘皋区为例,将该区遥感图像中提取的古河道信息层和数字化后的地形图上标注为独立物(其中包括已知、疑似遗址点)层叠合,在地理信息系统中总结已知遗址点的分布规律,筛选出疑似遗址点,并将其GPS定位信息与近期巢湖文物管理部门野外实测记录对比,提取的疑似遗址点中包含了普查记录的遗址.3s技术的应用表明,该方法可为考古普查工作节省大量时间、人力和物力.  相似文献   
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