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Crowdsourced knowledge websites such as Wikipedia and OpenStreetMap are increasingly attracting a critical literature which has highlighted the fact that the contributor bases of these sites are often geodemographically biased: drawn from more affluent and better educated segments of the population. However, while bias in contributors is well known, we know less about whether this also results in a bias in outcomes on these websites: or whether the partial portion of the population which does make contributions also works to “fill in the blanks”, by adding knowledge about other less well-off neighbouring areas which have not attracted a contributor base. This article addresses the question of whether such “neighbourhood effects” exist in practice. It makes use of a novel dataset of alcohol license data in the UK to assess variation in the completeness of the volunteer geographic information site OpenStreetMap. The results support existing literature in showing that completeness is related to demographics: areas with higher levels of wealth and education typically exhibit higher levels of completeness. The article then makes a novel contribution by showing evidence of the existence of neighbourhood effects: poorer regions with more affluent neighbours typically having higher levels of completeness than poorer regions which are also surrounded by poorer neighbours. The results suggest that crowdsourced knowledge websites can aspire to a kind of completeness even whilst user bases remain partial and biased. 相似文献
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Warren C. Jochem Kelly Sims Edward A. Bright Marie L. Urban Amy N. Rose Phillip R. Coleman Budhendra L. Bhaduri 《Natural Hazards》2013,68(3):1325-1342
In recent years, uses of high-resolution population distribution databases are increasing steadily for environmental, socioeconomic, public health, and disaster-related research and operations. With the development of daytime population distribution, temporal resolution of such databases has been improved. However, the lack of incorporation of transitional population, namely business and leisure travelers, leaves a significant population unaccounted for within the critical infrastructure networks, such as at transportation hubs. This paper presents two general methodologies for estimating passenger populations in airport and cruise port terminals at a high temporal resolution which can be incorporated into existing population distribution models. The methodologies are geographically scalable and are based on, and demonstrate how, two different transportation hubs with disparate temporal population dynamics can be modeled utilizing publicly available databases including novel data sources of flight activity from the Internet which are updated in near-real time. The airport population estimation model shows great potential for rapid implementation for a large collection of airports on a national scale, and the results suggest reasonable accuracy in the estimated passenger traffic. By incorporating population dynamics at high temporal resolutions into population distribution models, we hope to improve the estimates of populations exposed to or at risk to disasters, thereby improving emergency planning and response, and leading to more informed policy decisions. 相似文献
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An increasing volume of evidence suggests that normal faulting and graben formation associated with salt diapirism may be
catastrophic. The evidence includes: 1) removal of solid salt from the diapirs by dissolution, 2) the nature of rock outcrops
at the crests of domes, 3) seismic profiles showing recent displacement of the seafloor, and 4) changes in coral growth rates
at the East Flower Garden Bank. The possibility of catastrophic movement of the seabed is an engineering constraint that must
be addressed prior to emplacing structures such as jack-up rigs and production platforms. 相似文献
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Under the current framework embodied in the Kyoto Protocol and envisaged for future multilateral agreements, Annex I parties are obliged to limit their economy-wide GHG emissions and accept responsibility for exceeding their targets through various flexible mechanisms. The predominant sources of agricultural GHGs, which represent about 8% of total Annex I emissions, are methane and nitrous oxide from livestock. Efforts to reduce livestock emissions have so far been limited due to disagreements over the abatement potential, technical feasibility, and cost-effectiveness of the policy instruments available, including market-based measures. Two key challenges facing the application of market-based measures to livestock emissions are evaluated: first, to design a policy framework that appropriately aligns the measurement of emissions, the abatement options, and the incentives facing livestock producers; second, to address the risk of leakage and economic regrets that arise from unilateral domestic policy action. Particular attention is given to the policy developments in New Zealand and the lessons learnt from its experience. The challenges of applying market-based measures to livestock emissions are surmountable, but require innovative policy responses. 相似文献
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Several complex dynamic spatial systems are operating on the global scale. Their representation with existing geosimulation models is limited to planar level and do not consider the curvature of the Earth's surface. Thus, the objective of this study is to propose and develop a spherical geographic automata (SGA) modeling approach to represent and simulate dynamic spatial processes at the global level. The proposed SGA model is implemented for three case studies including simulations of: (1) Game of Life as population dynamics; (2) urban land-use growth; and (3) deforestation all operating on the spherical Earth's surface. Simulation results indicate that the proposed SGA modeling approach can represent spatial processes such as expansion and shrinkage dynamics on the Earth's surface. The proposed approach has the potential to be adopted to represent different complex systems such as ecological, epidemiological, socioeconomic, and Earth systems processes to support environmental management and policymaking at the global level. 相似文献
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Jordon Bright Darrell S. Kaufman Steven L. Forman William C. McIntosh Jim I. Mead Arturo Baez 《Quaternary Geochronology》2010,5(6):631-643
A recently discovered Bison-bearing fossil locality at Térapa, Sonora, Mexico, had previously been dated to 440 ± 130 ka using whole rock 40Ar/39Ar on a basalt flow that impounds the deposit. This age is considerably older than the accepted age of about 240–160 ka for the migration of Bison into greater North America. The Térapa deposit also contains a mixture of fossils from extralimital or extinct tropical animals and temperate animals. Constraining the age of the deposit is critical to interpret the paleontologic and paleoclimatologic implications of this unique Sonoran fossil locality. Three additional geochronological methods have been applied to this deposit (infrared stimulated luminescence (IRSL), amino acid racemization (AAR), and radiocarbon) and the data from the original 40Ar/39Ar age were revisited. The IRSL data suggest that the impounding basalt flow and the sediments that abut it were emplaced 43 ka ago and that the oldest sediments were deposited shortly after. Two radiocarbon ages suggest the fossiliferous sediments were emplaced by 42 ka. Effective diagenetic temperatures inferred from the AAR results, combined with AAR data from a similar-age deposit in southern Arizona, are in accordance with the 40–43 ka age estimates. For the AAR results to corroborate the 40Ar/39Ar age, the effective diagenetic temperature for the area would need to be approximately 3 °C, which is unrealistically low for northern Mexico. The new geochronological results suggest the Térapa deposit and fossils are 40–43 ka old. The anomalously old 40Ar/39Ar age for the impounding basalt is probably the result of low 40Ar* concentrations and inherited 40Ar. 相似文献
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Luminescence geochronology, especially infrared stimulated luminescence analyses on marsh mud, shows that a relatively deep lake reached its peak (1340 m above sea level) in the Bonneville basin 59,000±5000 yr ago. The age is consistent with nonfinite 14C ages and with amino acid geochronology on ostracodes. The Cutler Dam Alloformation was deposited during this lake cycle, which, like the subsequent Bonneville lake cycle, appears to have reached its maximum highstand following the peak of a global glacial stage (marine oxygen-isotope stage 4) but at a time when other records from North America show evidence for cold climate and expanded glacier ice. 相似文献
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Qiang Cai Gerard Rushton Budhendra Bhaduri Edward Bright Phillip Coleman 《Transactions in GIS》2006,10(4):577-598
The objective of this research is to compute population estimates by age and sex for small areas whose boundaries are different from those for which the population counts were made. In our approach, population surfaces and age‐sex proportion surfaces are separately estimated. Age‐sex population estimates for small areas and their confidence intervals are then computed using a binomial model with the two surfaces as inputs. The approach was implemented for Iowa using a 90 m resolution population grid (LandScan USA) and U.S. Census 2000 population. Three spatial interpolation methods, the areal weighting (AW) method, the ordinary kriging (OK) method, and a modification of the pycnophylactic method, were used on Census Tract populations to estimate the age‐sex proportion surfaces. To verify the model, age‐sex population estimates were computed for paired Block Groups that straddled Census Tracts and therefore were spatially misaligned with them. The pycnophylactic method and the OK method were more accurate than the AW method. The approach is general and can be used to estimate subgroup‐count types of variables from information in existing administrative areas for custom‐defined areas used as the spatial basis of support in other applications. 相似文献