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851.
Employees' work outcomes vary as a function of their focus on exploring new possibilities versus exploiting current opportunities. But what determines how employees divide their attention between these contrasting work behaviors? Drawing on studies on work motivation and employees' impression management concerns, we examine how intrinsic work motivation and self‐enhancement motivation relate to the exploration–exploitation balance and how environmental dynamism moderates these relationships. Based on the analyses of a sample of 638 employees in 34 organizations in Finland, we find that intrinsic work motivation is positively associated with employees' focus on exploration relative to exploitation. By contrast, self‐enhancement motivation negatively associates with exploration relative to exploitation, but this relationship is nonlinear, such that as self‐enhancement motivation increases, its positive association with exploitation diminishes. The findings also show that the hypothesized nonlinear relationship between self‐enhancement motivation and exploration is particularly pronounced in stable business environments. Our findings contribute to organizational learning research and provide a new theoretical perspective on pursuing exploration and exploitation in organizations.  相似文献   
852.
Large wood (LW) jams are key riverine habitat features that affect hydraulic processes and aquatic habitat. The hydraulic influence of LW jams is poorly understood due to the complexity of fluid dynamics around irregular, porous structures. Here we validated a method for two‐dimensional hydraulic modeling of porous LW jams using the open‐source modeling software Delft3D‐FLOW. We sampled 19 LW jams at three reaches across the Columbia River Basin in the United States. We used computer‐generated porous plates to represent LW jams in the modeling software and calibrated our modeling method by comparing model outputs to measured depths and velocities at validation points. We found that modeling outputs are error‐prone when LW jams are not represented. By representing LW jams as porous plates we reduced average velocity root mean square error (RMSE) values (i.e., improved model accuracy) by 42.8% and reduced average depth RMSE values by 5.2%. These differences impacted habitat suitability index modeling. We found a 15.1% increase in weighted useable area for juvenile steelhead at one test site when LW jams were simulated vs. when they were ignored. We investigated patterns in average RMSE improvements with varying jam size, bankfull obstruction, porosity, and structure type, and river complexity. We also identified research gaps related to field estimation of LW jam porosity and porous structure modeling methods.  相似文献   
853.
Heavy metal contamination is of particular concern for human health and the environment. Phytoremediation is an emerging cost‐effective strategy to remediate heavy metal contaminated soil. However, this technique is limited by the small number of plants that are tolerant to heavy metals and are also accumulators. This study assayed zinc, lead, and cadmium tolerance and accumulation in Cistus libanotis, Cistus albidus, and Cistus salviifolius. The plants were cultivated in hydroponic conditions and exposed to different concentrations of Pb(NO3)2 (100 and 200 µM), ZnSO4 (100 and 200 µM), or CdCl2 (10 and 20 µM) for 3 weeks. Plant biomass and metal accumulation in roots and aboveground parts varied greatly among the species. All three species appeared to be sensitive to Zn. However, C. albidus displayed strong tolerance to Pb and accumulated large quantities of Pb and Cd in its roots. C. libanotis accumulated large quantities of Pb and Cd in its aboveground parts. C. libanotis can thus be classified as a Pb and Cd accumulator species. The study results show that C. albidus is suitable for phytostabilization of Pb‐contaminated soils, while C. libanotis can be used for phytoextraction of both Pb and Cd.  相似文献   
854.
Abstract: Fecal coliform (FC) bacteria in coastal waters impair the use of these waters for shellfish harvesting and recreation. This study was designed to quantify and compare FC levels and export in two coastal watersheds with different land uses. Continuous monitoring of rainfall and discharge at three sites in the Jumping Run Creek watershed and one site in the Pettiford Creek watershed were conducted during a 4.5‐year period. Primary land use in the drainage area of one of the three Jumping Run Creek sites is low density industrial, while the other two are residential. Land use in the Pettiford Creek watershed is managed national forest. Nonstorm or base‐flow grab and flow‐proportional storm‐event samples were collected and analyzed for turbidity, conductivity, suspended sediment, nitrogen, phosphorus, and FC. Geometric mean FC levels for the Jumping Run Creek monitoring sites ranged from 593 to 2,096 mpn/100 ml, while the mean level at the Pettiford Creek site was 191 mpn/100 ml. Levels of most other parameters were greater in storm discharge from the Jumping Run Creek sites as compared to Pettiford Creek indicating that pollutant export from a watershed increases with development. Statistical analysis of the monitoring data suggested that FC levels in stormwater samples consistently increased with storm rainfall, but were not consistently correlated with any other parameter, including total suspended solids. Multivariate analysis indicated that the weekly FC export for each of the four sites was lowest during the December‐February quarter. Export was highest during the spring and summer at the Jumping Run Creek sites, while for the Pettiford Creek site, FC export was highest during September‐November. The cause of the seasonal variability was unknown but was thought to be associated with human activity in the watersheds.  相似文献   
855.
Abstract: It is now widely acknowledged that climate variability modulates the frequency of extreme hydrological events. Traditional methodologies for hydrologic frequency analysis are not devised to account for variation in the exogenous teleconnections. Flood frequency analysis is further plagued by the assumptions of stationary in the causal structure as well as ergodicity. Here, we propose a dynamical hierarchical Bayesian analysis to account for exogenous forcing that govern the summer season rainfall. The precursors for Korean summer rainfall at different frequencies are identified utilizing wavelet and independent component analyses. The sea surface temperatures, the ensemble of rainfall predictions by General Circulation Model, in addition to the typhoon attributes were found to have direct correlation with extreme rainfall events and were used as inputs to the logistic regression model. The model parameters are estimated using Markov Chain Monte Carlo and the resulting posterior distributions associated with individual inputs are analyzed to advance our understanding of the spatiotemporal impact of the teleconnections. Eight rainfall stations throughout Korea are considered in this analysis. We demonstrate that the probability of occurrence of extreme events could be successfully projected at a 90% rate of correct classification of extreme events.  相似文献   
856.
Abstract: An optimization procedure combining zonation methods with the Tabu Search method is proposed to identify the spatial distribution of hydraulic conductivity field. Three zonation methods, Voronoi diagram (VD), multiplicatively weighted Voronoi diagram (MWVD), and pattern zonation are adopted for the parameterization purposes. With the consideration of the homogeneity and the heterogeneity, there are four spatial distributions of hydraulic conductivity designed to test whether the parameter structure can be successfully identified. The fitting residual error is first considered to determine an adequate number of zones without over parameterization. Then, the parameter uncertainty is evaluated the decision of the number of zones. The results indicate that the MWVD performs better than other two methods because the MWVD has better flexibility in describing the zonal boundaries with small number of decision variables.  相似文献   
857.
The present study examined African‐American and White promotion candidates' reactions to and performance on selection procedures that were completed within a police department where African Americans occupied the majority of top‐management positions. Reactions (perceived job relatedness and test‐taking motivation) of 187 candidates competing for promotion to the rank of sergeant were assessed after completing a written job knowledge test and a situational interview. Analyses showed that both the African‐American and White candidates judged the situational interview to be more job‐related than the pencil‐and‐paper job knowledge test. In addition, African Americans perceived both selection measures to be more job‐related and reported higher levels of test‐taking motivation than White candidates even though African Americans performed more poorly than White candidates on the paper‐and‐pencil test. These results challenge the contention that lower test‐taking motivation for African‐American candidates is related to racial differences in performance on pencil‐ and‐paper tests. Implications and directions for future research on reactions to selection procedures for promotion in racially diverse employment settings are discussed. Copyright © 2007 John Wiley & Sons, Ltd.  相似文献   
858.
This study tested a relational demography model of workgroup identification. We theorized that early in workgroup formation, (a) racial identification would moderate the influence of racial dissimilarity on member communication behavior (frequency and length of verbal participation) during a group task, (b) member communication behaviors would mediate the effect of racial dissimilarity on workgroup identification, and that (c) these effects would be affected non‐symmetrically by racial group membership (White, Black). This model was tested among a sample of 211 undergraduates (113 White and 98 Black), working in 43 temporary workgroups. Whites' racial identification moderated the relationship between racial dissimilarity and member communication behaviors, which in turn partially mediated the effect of racial dissimilarity on workgroup identification, generally consistent with our model. Among Black workgroup members support for our model was limited. Copyright © 2008 John Wiley & Sons, Ltd.  相似文献   
859.
A growing awareness of the value of indigenous knowledge has prompted calls for its use within disaster risk reduction. The use of indigenous knowledge alongside scientific knowledge is increasingly advocated but there is as yet no clearly developed framework demonstrating how the two may be integrated to reduce community vulnerability to environmental hazards. This paper presents such a framework, using a participatory approach in which relevant indigenous and scientific knowledge may be integrated to reduce a community's vulnerability to environmental hazards. Focusing on small island developing states it presents an analysis of the need for such a framework alongside the difficulties of incorporating indigenous knowledge. This is followed by an explanation of the various processes within the framework, drawing on research completed in Papua New Guinea. This framework is an important first step in identifying how indigenous and scientific knowledge may be integrated to reduce community vulnerability to environmental hazards.  相似文献   
860.
This paper reports on an examination of data on how local residents in Tuscaloosa, a mid‐sized city in the state of Alabama, United States, responded to Hurricane Ivan of September 2004. The evaluation revealed that an integrated connection to community‐level communication resources—comprising local media, community organisations and interpersonal networks—has a direct impact on the likelihood of engaging in pre‐hurricane preparedness activities and an indirect effect on during‐hurricane preparedness activities. Neighbourhood belonging mediated the relation between an integrated connection to community‐level communication resources and during‐hurricane preparedness activities. Neighbourhood belonging was determined to increase the likelihood of taking preparedness actions during Hurricane Ivan, but not prior to it. In addition, we discovered an interesting pattern for two different types of risk perceptions: social and personal risk perceptions. Social risk perceptions increase the likelihood of taking preventative steps before a hurricane while personal risk perceptions are positively related to engaging in preventative action during a hurricane.  相似文献   
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