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51.
52.
El Mohtar Chadi Jaffal Hamza Miller Anna Kate Ward Katie 《Geotechnical and Geological Engineering》2022,40(9):4473-4485
Geotechnical and Geological Engineering - Permeation grouting is a ground improvement method commonly used for strengthening and/or reducing permeability of soils with minimal disturbance to the... 相似文献
53.
Physiological tolerances limit the distribution of marine species, with geographical ranges being set by environmental factors, such as temperature and salinity, which affect the rates of vital processes and survival of marine ectotherms. The physiological tolerances of the non-native marine amphipod Caprella mutica were investigated in laboratory experiments. Adult C. mutica were collected from a fish farm on the west coast of Scotland and exposed to a range of temperatures and salinities for 48 h. C. mutica were tolerant of a broad range of temperature and salinity conditions, with 100% mortality at 30 degrees C (48 h LT50, 28.3+/-0.4 degrees C), and salinities lower than 16 (48 h LC50, 18.7+/-0.2). Although lethargic at low temperatures (2 degrees C), no mortality was observed, and the species is known to survive at temperatures as low as -1.8 degrees C. The upper LC(50) was greater than the highest salinity tested (40), thus it is unlikely that salinity will limit the distribution of C. mutica in open coastal waters. However, the species will be excluded from brackish water environments such as the heads of sea lochs or estuaries. The physiological tolerances of C. mutica are beyond the physical conditions experienced in its native or introduced range and are thus unlikely to be the primary factors limiting its present distribution and future spread. 相似文献
54.
This paper explores young people’s experiences and perceptions of mobility and mobility constraints in poorer urban areas of Ghana, Malawi and South Africa within the specific context of inter-generational relations. Drawing principally on qualitative research findings from a study involving both adult and child researchers, our aim is to chart the diversities and commonalities of urban young people’s mobility experiences in the everyday - how they use and experience the city - developing a comparative perspective across three urban study sites which links young people’s mobility with the power relations that operate to shape their movements in individual locations. In particular, we consider how positive and negative images of young people’s mobility play out in terms of the inter-generational frictions and negotiations generated by their mobility performances. We also reflect on the developmental implications, in terms of young people’s access to services and income and their participation in the social networks and peer culture which may shape their life trajectories. Three themes are explored in detail: mobility as challenge, mobility as temptation and mobility control. 相似文献
55.
David E. Anderson Eleanor J. Brown 《Proceedings of the Geologists' Association. Geologists' Association》2010,121(4):455-467
Outreach arising from the study of the British Quaternary offers many benefits for society, especially because of its relevance for understanding contemporary environmental issues and environmental change. Outreach is also important for the long-term health of the academic discipline and research agenda. Through engaging with the formal education system, institutions, policy makers, planners and with the public at large, Quaternary specialists can do much to advance interest in and appreciation of the British landscape and its Quaternary record. This opinion and review article considers the importance and benefits of outreach in its many forms, makes the case for practitioners to continue and increase their involvement, offers examples of good practice, and sets out aspirations for the future. 相似文献
56.
Detlef P. van Vuuren Jae Edmonds Steven J. Smith Kate V. Calvin Joseph Karas Mikiko Kainuma Nebojsa Nakicenovic Keywan Riahi Bas J. van Ruijven Rob Swart Allison Thomson 《Climatic change》2010,103(3-4):635-642
Long-term scenarios developed by integrated assessment models are used in climate research to provide an indication of plausible long-term emissions of greenhouse gases and other radiatively active substances based on developments in the global energy system, land-use and the emissions associated with these systems. The phenomena that determine these long-term developments (several decades or even centuries) are very different than those that operate on a shorter time-scales (a few years). Nevertheless, in the literature, we still often find direct comparisons between short-term observations and long-term developments that do not take into account the differing dynamics over these time scales. In this letter, we discuss some of the differences between the factors that operate in the short term and those that operate in the long term. We use long-term historical emissions trends to show that short-term observations are very poor indicators of long-term future emissions developments. Based on this, we conclude that the performance of long-term scenarios should be evaluated against the appropriate, corresponding long-term variables and trends. The research community may facilitate this by developing appropriate data sets and protocols that can be used to test the performance of long-term scenarios and the models that produce them. 相似文献
57.
Ecosystem-based fishery management (EBFM) requires taking account of indirect effects (such as habitat destruction, incidental mortality, and competition between the fishery and marine mammals or birds) and dealing with non-commensurate values (such as yield from the fishery and production of offspring by the birds or mammals competing for the same resource). The perspective of EBFM requires that the rate of fishing mortality is less than the value that provides maximum sustainable yield (MSY), but the question is how far below this level should the fishery operate? For this problem in multiobjective programming, simple method of solution was developed and illustrated with the fishery for sandeels (Ammodytes spp.) in the Shetland Islands. The yield from the fishery at a given fishing mortality F is scaled by MSY (so that this quantity increases as fishing mortality increases from 0 to that giving MSY) and the breeding success of predators (black-legged kittiwakes Rissa tridactyla and Arctic terns Sterna paradisaea) at a given fishing mortality is scaled by that in the absence of fishing. The result is two non-dimensional quantities that can be combined into a single value function, which can then be explored or optimized. It is shown that a reduction of only about 20 percent in yield can nearly double the breeding performance of the more sensitive predator. Extensions of the method are discussed; these include the use of maximum economic yield (MEY) and state dependent life history, as implemented by stochastic dynamic programming. 相似文献
58.
Isaac Luginaah Michael Jerrett Susan Elliott John Eyles Kate Parizeau Stephen Birch Tom Abernathy Gerry Veenstra Brian Hutchinson Chris Giovis 《GeoJournal》2001,53(2):135-147
This paper is part of a larger research program which employs a mixed-methods approach to study the determinants of health at the local level using specific neighborhoods in Hamilton, Ontario, Canada. In this paper, multivariate, spatial statistical techniques and geographic information systems are used to address questions about the characterization of neighbourhoods, based on socioeconomic determinants of health and risk factors such as smoking. While neighbourhood characterization has been a component of public health surveillance for some time, geostatistical techniques can now be used to derive more accurate representation of neighbourhoods for use in subsequent analysis. We utilize principal components analysis to reduce the data and extract the components that represent the underlying local processes. Principal components are also overlayed on comparative mortality figures to visualize where the socio-demographic determinants of health correspond spatially with mortality patterns. Predicted values from the components are then analysed for spatial clustering using local indicators of spatial association. The findings reveal a pattern of distinct neighbourhoods that will be used in subsequent quantitative and qualitative stages in the larger research programme. The results can also be used to inform public health policy and to target public health interventions. 相似文献
59.
Kate Boyer 《The Professional geographer》2004,56(2):201-212
At the end of the 19th century, the financial services sector underwent a technological “revolution” with the invention of the typewriter, dictaphone, and hollerith machine. At the same time, the gender of labor within this sector was also changing, such that by the end of the first quarter of the 20th century, most of the work taking place in white‐collar offices was performed by women. After introducing the broader research project on which this is based, I consider how technology and social relations shaped one another at the level of the body, the workplace, and with broader networks of branch banking, focusing on early 20th‐century Montreal, Canada. I argue that the financial services sector worked to create a system in which men flowed through and women functioned as fixed points. I further argue that this pattern was echoed at different scales within the financial services industry, from the level of the body and the workplace up through spatially dispersed national‐level networks. 相似文献
60.
Siberian rivers are of global importance as they impact on the freshwater budget of the Arctic Ocean, which affects the Thermo-Haline circulation in the North Atlantic Ocean. Siberian rivers, in particular the tributaries to the larger rivers, are under-represented in the international river-regime databases. The runoff of three Russian rivers in the Central Siberian taiga (Kureyka, Karabula and Erba) is modelled to analyse the relative influence of climate. In addition three rivers (Rhine, Maas and Odra) in Western Europe are similarly assessed as a control. The results show that the role of precipitation and autocorrelation as factors in the formation of river runoff is stronger under oceanic climate conditions, increasing from the central regions of Northern Eurasia towards the Arctic Ocean in the North and the Atlantic in the West. At the same time the influence of summer temperatures is weakened. The formation of Northern Eurasian river runoff appears to be influenced by periodically thawing top horizons of permafrost soil. Time served as an indicator for land use change after inclusion of meteorological data in the models. Maas and Erba showed a significant influence of the time factor. For the Erba the onset of agricultural land use in the catchment coincides with a drop in runoff. A similar causal relationship is suggested for the Maas. Land use can change the formation of runoff, which in turn can be used as an environmental indicator for sustainable land use. 相似文献