Mapping collective human activity in an urban environment based on mobile phone data   总被引：1，自引：0，他引：1  

Guenther Sagl  Eric Delmelle  Elizabeth Delmelle 《制图学和地理信息科学》2014,41(3):272-285

Identifying and characterizing variations of human activity – specifically changes in intensity and similarity – in urban environments provide insights into the social component of those eminently complex systems. Using large volumes of user-generated mobile phone data, we derive mobile communication profiles that we use as a proxy for the collective human activity. In this article, geocomputational methods and geovisual analytics such as self-organizing maps (SOM) are used to explore the variations of these profiles, and its implications for collective human activity. We evaluate the merits of SOM as a cross-dimensional clustering technique and derived temporal trajectories of variations within the mobile communication profiles. The trajectories’ characteristics such as length are discussed, suggesting spatial variations in intensity and similarity in collective human activity. Trajectories are linked back to the geographic space to map the spatial and temporal variation of trajectory characteristics. Different trajectory lengths suggest that mobile phone activity is correlated with the spatial configuration of the city, and so at different times of the day. Our approach contributes to the understanding of the space-time social dynamics within urban environments.  相似文献   

Variation and pattern in the responses of mammal faunas to Late Pleistocene climatic change in southeastern South Australia     

Amy C. Macken  Gavin J. Prideaux  Elizabeth H. Reed 《第四纪科学杂志》2012,27(4):415-424

We examined mammal occurrence and variability through the Late Pleistocene vertebrate fossil deposit of Grant Hall in Victoria Fossil Cave, Naracoorte, South Australia. To determine long‐term patterns of change, we compared the composition and relative abundance trends of the assemblage with a nearby Middle Pleistocene deposit in Cathedral Cave. Total species richness did not change through the Grant Hall sequence, dated from 93 ± 8 to 70 ± 5 ka. However, species relative abundances varied between ecologically divergent species, and in some cases between species that demonstrate similar environmental preferences. For some species this variation is comparable to that recorded in Cathedral Cave. Of those showing similar trends between the two deposits, the forest inhabitant, Pseudomys fumeus, recorded an 8.6% decline through Grant Hall, coincident with a 9.7% increase in the dry heath/mallee dweller Pseudomys apodemoides. These patterns indicate that climatic transition from relatively warm, moist to cooler, drier conditions impacted some species in similar ways through climatic cycles of the past. However, the majority of the fauna demonstrated complex responses that are individual and variable through time. Statistical tests of species trends from the Grant Hall assemblage caution that large fossil samples are required to validate patterns observed. Copyright © 2012 John Wiley & Sons, Ltd.  相似文献   

‘Whose science?’ Precaution and power-play in European marine environmental decision-making     

Elizabeth M. De Santo 《Marine Policy》2010,34(3):414-420

This paper explores the science–policy interface in environmental decision-making in the European Community as it moves towards its stated aims of implementing a precautionary and ecosystem-based approach to marine environmental management. Whilst recent EC case law has clarified some questions of Member State responsibilities under international environmental obligations, recent case studies at the crossing point between marine nature conservation and fisheries management in EC waters raise questions about the role of science in policy-making in Brussels. This has important implications for the developing EC Integrated Maritime Policy and Marine Strategy Framework Directive, and the concept of Maritime Spatial Planning as a whole. A new paradigm for bridging the science–policy gap is required in light of the developing legislative framework and given the complex nature of the marine environment.  相似文献   

Fossils explained 50     

Elizabeth M. Harper 《Geology Today》2005,21(5):191-196

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The effect of drawdown on suspended solids and phosphorus export from Columbia Lake,Waterloo, Canada     

Mike Shantz  Elizabeth Dowsett  Emma Canham  Guillaume Tavernier  Mike Stone  Jonathan Price 《水文研究》2004,18(5):865-878

This study examines the effect of drawdown on the timing and magnitude of suspended solids and associated phosphorus export from a 12 ha reservoir located in an urbanized watershed in southern Ontario, Canada. Water level in Columbia Lake was lowered by 1·15 m over a 2‐week period in November 2001. The total phosphorus (TP) concentrations ranged from 63 to 486 µg L^?1 in Columbia Lake and 71 to 373 µg L^?1 at its outflow. All samples exceeded the Provincial Water Quality Objective of 30 µg TP L^?1. Outflow concentrations of suspended solids and TP increased significantly with decreasing lake level and were attributed to the resuspension of cohesive bottom sediments that occurred at a critical threshold lake level (0·65 m below summer level). Suspended solids at the outflow consisted of flocculated cohesive materials with a median diameter (D₅₀) of c. 5 µm. Particulate organic carbon accounted for 8·5% of the suspended solids export by mass. A total mass of 18·5 t of suspended solids and 62·6 kg TP was exported from Columbia Lake, which represents a significant pulse of sediment‐associated P to downstream environments each autumn during drawdown. The downstream impacts of this release can be minimized if the water level in Columbia Lake is lowered no more than 0·5 m below summer levels. Copyright © 2004 John Wiley & Sons, Ltd.  相似文献   

A Simple Relation to Constrain Groundwater Models Using Surface Deformation     

Megan R.M. Brown  Shemin Ge  Elizabeth Screaton 《Ground water》2022,60(3):410-417

A simple relation between pore pressure change and one-dimensional surface deformation is presented. The relation is for pore pressure change in a confined aquifer that causes surface deformation. It can be applied to groundwater models of any discretization and is computationally efficient. The estimated surface deformation from model results can be compared to observed surface deformation through geodetic techniques such as Differential Interferometric Synthetic Aperture Radar. Model parameters then are constrained using the observed surface deformation. The validity of this relation is shown through constraint of model parameters for surface uplift due to pore pressure increase caused by wastewater disposal injection.  相似文献   

The early Miocene paleolake Manuherikia: vegetation heterogeneity and warm-temperate to subtropical climate in southern New Zealand     

Tammo Reichgelt  Elizabeth M. Kennedy  John G. Conran  Dallas C. Mildenhall  Daphne E. Lee 《Journal of Paleolimnology》2015,53(4):349-365

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Global distribution of the intensity and frequency of hourly precipitation and their responses to ENSO     

Li  Xiao-Feng  Blenkinsop  Stephen  Barbero  Renaud  Yu  Jingjing  Lewis  Elizabeth  Lenderink  Geert  Guerreiro  Selma  Chan  Steven  Li  Yafei  Ali  Haider  Villalobos Herrera  Roberto  Kendon  Elizabeth  Fowler  Hayley J. 《Climate Dynamics》2020,54(11):4823-4839

Climate Dynamics - We investigate the global distribution of hourly precipitation and its connections with the El Niño–Southern Oscillation (ENSO) using both satellite precipitation...  相似文献   

Behaviour of the winter North Atlantic eddy-driven jet stream in the CMIP3 integrations   总被引：1，自引：1，他引：0  

Abdel Hannachi  Elizabeth A. Barnes  Tim Woollings 《Climate Dynamics》2013,41(3-4):995-1007

A systematic analysis of the winter North Atlantic eddy-driven jet stream latitude and wind speed from 52 model integrations, taken from the coupled model intercomparison project phase 3, is carried out and compared to results obtained from the ERA-40 reanalyses. We consider here a control simulation, twentieth century simulation, and two time periods (2046–2065 and 2081–2100) from a twenty-first century, high-emission A2 forced simulation. The jet wind speed seasonality is found to be similar between the twentieth century simulations and the ERA-40 reanalyses and also between the control and forced simulations although nearly half of the models overestimate the amplitude of the seasonal cycle. A systematic equatorward bias of the models jet latitude seasonality, by up to 7°, is observed, and models additionally overestimate the seasonal cycle of jet latitude about the mean, with the majority of the models showing equatorward and poleward biases during the cold and warm seasons respectively. A main finding of this work is that no GCM under any forcing scenario considered here is able to simulate the trimodal behaviour of the observed jet latitude distribution. The models suffer from serious problems in the structure of jet variability, rather than just quantitiative errors in the statistical moments.  相似文献   

Can agriculture support climate change adaptation, greenhouse gas mitigation and rural livelihoods? insights from Kenya     

Elizabeth Bryan  Claudia Ringler  Barrack Okoba  Jawoo Koo  Mario Herrero  Silvia Silvestri 《Climatic change》2013,118(2):151-165

Changes in the agriculture sector are essential to mitigate and adapt to climate change, meet growing food demands, and improve the livelihoods of poor smallholder producers. What agricultural strategies are needed to meet these challenges? To what extent are there synergies among these strategies? This paper examines these issues for smallholder producers in Kenya across several agroecological zones. Several practices emerge as triple wins, supporting climate adaptation, greenhouse gas mitigation, and profitability goals. In particular, integrated soil fertility management and improved livestock feeding are shown to provide multiple benefits across all agroecological zones examined. Triple wins of other agricultural practices are limited to specific agroecological zones. Irrigation and soil and water conservation, for example, are essential for adaptation, mitigation, and profitability in arid areas. The results suggest that agricultural investments targeted toward these triple-win strategies will have the greatest payoff in terms of increased resilience of farm and pastoralist households and global climate change mitigation. To reap the benefits of triple-win strategies will require that policymakers, researchers, and practitioners move away from isolated approaches focused on either adaptation or mitigation or rural income generation toward a more holistic assessment of joint strategies as well as their tradeoffs and synergies.  相似文献