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371.
372.
Nick Novakowski 《GeoJournal》2010,75(6):553-565
This research provides a comparative examination of Ottawa as an archetype of a knowledge city. Among Canada’s four largest
cities, Ottawa is unique in terms of the characteristics of its labor force, the nature of its employment mix, and its infrastructure.
Since the high-tech downturn of 2001, some of Ottawa’s options as a knowledge city seem to be contracting, despite some simultaneously
encouraging signs (like recovering employment levels in the high-tech sector). This raises a question about Ottawa’s potential
longevity as a knowledge center. The challenge is to understand the inventory of obstacles faced by the city, and address
the sort of alchemy required to maintain and improve its competitiveness as a knowledge city. 相似文献
373.
High-resolution rockfall inventories captured at a regional scale are scarce. This is partly owing to difficulties in measuring the range of possible rockfall volumes with sufficient accuracy and completeness, and at a scale exceeding the influence of localized controls. This paucity of data restricts our ability to abstract patterns of erosion, identify long-term changes in behaviour and assess how rockfalls respond to changes in rock mass structural and environmental conditions. We have addressed this by developing a workflow that is tailored to monitoring rockfalls and the resulting cliff retreat continuously (in space), in three-dimensional (3D) and over large spatial scales (>104 m). We tested our approach by analysing rockfall activity along 20.5 km of coastal cliffs in North Yorkshire (UK), in what we understand to be the first multi-temporal detection of rockfalls at a regional scale. We show that rockfall magnitude–frequency relationships, which often underpin predictive models of erosion, are highly sensitive to the spatial extent of monitoring. Variations in rockfall shape with volume also imply a systemic shift in the underlying mechanisms of detachment with scale, leading us to question the validity of applying a single probabilistic model to the full range of rockfalls observed here. Finally, our data emphasize the importance of cliff retreat as an episodic process. Going forwards, there will a pressing need to understand and model the erosional response of such coastlines to rising global sea levels as well as projected changes to winds, tides, wave climates, precipitation and storm events. The methodologies and data presented here are fundamental to achieving this, marking a step-change in our ability to understand the competing effects of different processes in determining the magnitude and frequency of rockfall activity and ultimately meaning that we are better placed to investigate relationships between process and form/erosion at critical, regional scales. © 2020 The Authors. Earth Surface Processes and Landforms published by John Wiley & Sons Ltd 相似文献
374.
Some 60% of the agricultural land in the UK is grassland. This is mostly located in the wetter uplands of the west and north, with the majority intensively managed as permanent pasture. Despite its extent, there is a lack of knowledge regarding how agricultural practices have altered the hydrological behaviour of the underlying soils relative to the adjacent moorland covered by semi-natural grassland. Near-surface soil moisture content is an expression of the changes that have taken place and is critical in the generation of flood-producing overland flows. This study aims to develop a pioneering paired-plot approach, producing 1,536 moisture measurements at each of the monitoring dates throughout the studied year, that were subsequently analysed by a comparison of frequency distributions, visual cum geostatistical investigation of spatial patterns and mixed-effects regression modelling. The analysis demonstrated that the practices taking place in the pasture (ploughing, re-seeding and drainage) reduced the natural diversity in moisture patterns. Compared to adjacent moorland, the topsoil dried much faster in spring with the effects requiring offset with moisture from slurry applications in summer. With the onset of autumn rains, these applications then made the topsoil wetter than the moorland, heightening the likelihood of flood-producing overland flow. During the sampling within one such storm event, the adjacent moorland was almost as wet as the pasture with both visibly generating overland flow. These contrasts in soil moisture were statistically significant throughout. Further, they highlight the need to scale-up the monitoring with numerous plot pairs to see if the observed highly dynamic, contrasting behaviour is present at the landscape scale. Such research is fundamental to designing appropriate agricultural interventions to deliver sustainable sward production for livestock or methods of mitigating overland-flow incidence that would otherwise heighten flood risk or threaten water quality in rivers. 相似文献
375.
Stephen Serjeant Seb Oliver † Michael Rowan-Robinson Hans Crockett Vasilis Missoulis Tim Sumner Carlotta Gruppioni Robert G. Mann Nick Eaton David Elbaz David L. Clements Amanda Baker reas Efstathiou Catherine Cesarsky Luigi Danese Alberto Franceschini Reinhardt Genzel y Lawrence Dietrich Lemke Richard G. McMahon George Miley Jean-Loup Puget Brigitte Rocca-Volmerange 《Monthly notices of the Royal Astronomical Society》2000,316(4):768-778
376.
377.
The evaluation of the potential impact of strong seismic events shortly after their occurrence is a critical step to organise emergency response and consequently minimise the adverse effects of earthquakes. The estimation of the impact from earthquakes considering the observed ground shaking from past events can be useful for the calibration of existing exposure and/or fragility and vulnerability models. This study describes a methodology to combine the publicly available information from the USGS ShakeMap system and the open-source software OpenQuake engine for the assessment of damage and losses. This approach is employed to estimate the number of structural collapses considering the 2012 Magnitude 5.9 Emilia-Romagna (Italy) earthquake and the aggregated economic loss because of the 2010 Magnitude 7.1 Darfield (New Zealand) event. Several techniques to calculate the ground shaking in the affected region considering the spatial and interperiod correlations in the intra-event ground motion residuals are investigated and their influence in the resulting damage or loss estimates are evaluated. 相似文献
378.
Diversity within a population has been linked to levels of both social cohesion and crime. Neighborhood crimes are the result of a complex set of factors, one of which is weak community cohesion. This article seeks to explore the impacts of diversity on burglary crime in a range of neighborhoods, using Leeds, UK as a case study. We propose a new approach to quantifying the correlates of burglary in urban areas through the use of diversity metrics. This approach is useful in unveiling the relationship between burglary and diversity in urban communities. Specifically, we employ stepwise multiple regression models to quantify the relationships between a number of neighborhood diversity variables and burglary crime rates. The results of the analyses show that the variables that represent diversity were more significant when regressed against burglary crime rates than standard socio‐demographic data traditionally used in crime studies, which do not generally use diversity variables. The findings of this study highlight the importance of neighborhood cohesion in the crime system, and the key place for diversity statistics in quantifying the relationships between neighborhood diversities and burglary. The study highlights the importance of policy planning aimed at encouraging community building in promoting neighborhood safety. 相似文献
379.
Peter Jenniskens Nick Moskovitz Laurence A. J. Garvie Qing‐Zhu Yin J. Andreas Howell Dwayne L. Free Jim Albers David Samuels Marc D. Fries Prajkta Mane Daniel R. Dunlap Karen Ziegler Matthew E. Sanborn Qin Zhou Qiu‐Li Li Xian‐Hua Li Yu Liu Guo‐Qiang Tang Kees C. Welten Marc W. Caffee Henner Busemann Matthias M. M. Meier David Nesvorny 《Meteoritics & planetary science》2020,55(3):535-557
The trajectory and orbit of the LL7 ordinary chondrite Dishchii'bikoh are derived from low‐light video observations of a fireball first detected at 10:56:26 UTC on June 2, 2016. Results show a relatively steep ~21° inclined orbit and a short 1.13 AU semimajor axis. Following entry in Earth's atmosphere, the meteor luminosity oscillated corresponding to a meteoroid spin rate of 2.28 ± 0.02 rotations per second. A large fragment broke off at 44 km altitude. Further down, mass was lost to dust during flares at altitudes of 34, 29, and 25 km. Surviving meteorites were detected by Doppler weather radar and several small 0.9–29 g meteorites were recovered under the radar reflection footprint. Based on cosmogenic radionuclides and ground‐based radiometric observations, the Dishchii'bikoh meteoroid was 80 ± 20 cm in diameter assuming the density was 3.5 g/cm3. The meteoroid's collisional history confirms that the unusual petrologic class of LL7 does not require a different parent body than three previously observed LL chondrite falls. Dishchii'bikoh was ejected 11 Ma ago from parent body material that has a 4471 ± 6 Ma U‐Pb age, the same as that of Chelyabinsk (4452 ± 21 Ma). The distribution of the four known pre‐impact LL chondrite orbits is best matched by dynamical modeling if the source of LL chondrites is in the inner asteroid belt in a low inclined orbit, with the highly inclined Dishchii'bikoh being the result of interactions with Earth before impacting. 相似文献