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排序方式: 共有247条查询结果,搜索用时 15 毫秒
211.
Alfred Becker Volker Wenzel Valentina Krysanova Werner Lahmer 《Environmental Modeling and Assessment》1999,4(4):243-257
The paper introduces an approach for the analysis of global change impacts on river basins or regions. This approach is quite general and can be transferred to any region or river basin of interest on earth. The first application of the approach was in the Elbe river basin, with primary focus on the hydrologic model part and on the integration of crop growth and nitrogen dynamics. Finally, concepts for the integration of socio-economic aspects in the analysis are introduced. 相似文献
212.
Vander Pol SS Hobson KA Becker PR Day RD Ellisor MB Pugh RS Roseneau DG 《Journal of environmental monitoring : JEM》2011,13(3):699-705
The contents from thick-billed murre (Uria lomvia) eggs collected at four Alaskan colonies in 2002 were analyzed for organic contaminants and carbon δ13C) and nitrogen (δ1?N) stable isotopes. Contaminant concentrations in the eggs varied from below detection limits to 230 ng g?1 wet mass for 4,4'-DDE in one egg from St Lazaria Island in the Gulf of Alaska. Eggs from this colony generally contained higher levels of contaminants and exhibited significantly different patterns compared to eggs from the Bering and Chukchi seas. Stable isotope values also varied geographically; however, these differences appeared to be related to differences in C and N baselines in the food webs instead of differences in prey. Contaminant and stable isotope correlations were inconclusive, suggesting that better information on regional food web differences and differential offloading of contaminants and stable isotopes to the eggs must be obtained before these kinds of data can be fully incorporated into seabird egg contaminant monitoring programs. 相似文献
213.
Francis Turkelboom Rolinde Demeyer Liesbet Vranken Piet De Becker Filip Raymaekers Lieven De Smet 《Ambio》2021,50(8):1431
The strategy of reconnecting rivers with their floodplains currently gains popularity because it not only harnesses natural capacities of floodplains but also increases social co-benefits and biodiversity. In this paper, we present an example of a successfully implemented nature-based solution (NBS) in the Dijle valley in the centre of Belgium. The research objective is to retrospectively assess cost and benefit differences between a technical solution (storm basins) and an alternative NBS, here the restoration of the alluvial floodplain. The method is a comparative social cost–benefit analysis. The case study analysis reveals similar flood security, lower costs, more ecosystem services benefits and higher biodiversity values associated with the NBS option in comparison to the technical alternative. However, the business case for working with NBS depends substantially on the spatial and socio-ecological context. Chances for successful NBS implementation increase in conditions of sufficient space to retain flood water, when flood water is of sufficient quality, and when economic activity and housing in the floodplain is limited.Supplementary InformationThe online version of this article contains supplementary material available at (10.1007/s13280-021-01548-4). 相似文献
214.
William Becker 《Conservation biology》2009,23(4):794-795
215.
Statistical control in correlational studies: 10 essential recommendations for organizational researchers 下载免费PDF全文
Thomas E. Becker Guclu Atinc James A. Breaugh Kevin D. Carlson Jeffrey R. Edwards Paul E. Spector 《组织行为杂志》2016,37(2):157-167
Statistical control is widely used in correlational studies with the intent of providing more accurate estimates of relationships among variables, more conservative tests of hypotheses, or ruling out alternative explanations for empirical findings. However, the use of control variables can produce uninterpretable parameter estimates, erroneous inferences, irreplicable results, and other barriers to scientific progress. As a result, methodologists have provided a great deal of advice regarding the use of statistical control, to the point that researchers might have difficulties sifting through and prioritizing the available suggestions. We integrate and condense this literature into a set of 10 essential recommendations that are generally applicable and which, if followed, would substantially enhance the quality of published organizational research. We provide explanations, qualifications, and examples following each recommendation. Copyright © 2015 John Wiley & Sons, Ltd. 相似文献
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The cross-impact assessment process (CAP) is presented as a practical method for efficiently identifying a parsimonious set of critically important variables and associated relationships needed to conduct environmental impact studies. CAP was developed from the logic of a number of techniques that are collectively referred to as cross-impact analysis. The process is based on a series of structured workshops. The participants represent a variety of disciplines and individual members are selected because they have both the depth of understanding necessary to contribute specific knowledge on the environmental impact assessment problem and the breadth of view to integrate that knowledge with the information provided by other panelists. The results of the workshops are summarized in an importance index and presented in a cross-impact matrix. CAP is illustrated with an example from an Upper Mississippi River recreation impact study, but it can also be applied to any environmental impact assessment problem that can be characterized as a system of variables and relationships. CAP also provides an efficient and reasonably objective means for assigning priorities to environmental impact studies. 相似文献
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Becker MW Collins SA Metge DW Harvey RW Shapiro AM 《Journal of contaminant hydrology》2004,69(3-4):195-213
The influence of physicochemical characteristics and motility on bacterial transport in groundwater were examined in flow-through columns. Four strains of bacteria isolated from a crystalline rock groundwater system were investigated, with carboxylate-modified and amidine-modified latex microspheres and bromide as reference tracers. The bacterial isolates included a gram-positive rod (ML1), a gram-negative motile rod (ML2), a nonmotile mutant of ML2 (ML2m), and a gram-positive coccoid (ML3). Experiments were repeated at two flow velocities, in a glass column packed with glass beads, and in another packed with iron-oxyhydroxide coated glass beads. Bacteria breakthrough curves were interpreted using a transport equation that incorporates a sorption model from microscopic observation of bacterial deposition in flow-cell experiments. The model predicts that bacterial desorption rate will decrease exponentially with the amount of time the cell is attached to the solid surface. Desorption kinetics appeared to influence transport at the lower flow rate, but were not discernable at the higher flow rate. Iron-oxyhydroxide coatings had a lower-than-expected effect on bacterial breakthrough and no effect on the microsphere recovery in the column experiments. Cell wall type and shape also had minor effects on breakthrough. Motility tended to increase the adsorption rate, and decrease the desorption rate. The transport model predicts that at field scale, desorption rate kinetics may be important to the prediction of bacteria transport rates. 相似文献