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571.
This study examines factors affecting employees' perceptions that their psychological contract has been breached by their organization, and factors affecting whether this perception will cause employees to experience feelings of contract violation. Data were obtained from 147 managers just prior to their beginning of new job (time 1) and 18 months later (time 2). It was found that perceived contract breach at time 2 was more likely when organizational performance and self‐reported employee performance were low, the employee had not experienced a formal socialization process, the employee had little interaction with organizational agents prior to hire, the employee had a history of psychological contract breach with former employers, and the employee had many employment alternatives at the time of hire. Furthermore, perceived breach was associated with more intense feelings of violation when employees both attributed the breach to purposeful reneging by the employer and felt unfairly treated in the process. Theoretical and practical implications of these results are discussed. Copyright © 2000 John Wiley & Sons, Ltd.  相似文献   
572.
This study explores the economic attractiveness of afforestation as a strategy for the joint production of fibre, carbon storage and biosolids (treated municipal sewage sludge) disposal for municipalities in Southern and Central Ontario, Canada. We use a spatial, stochastic model, the Canadian Forest Service Afforestation Feasibility Model (CFS-AFM), to simulate a range of spatial biosolids application scenarios in hybrid poplar afforestation projects. Results suggest that such joint afforestation strategies could be financially attractive. Significant cost savings can be expected through decreases in transportation distances and avoided waste disposal fees. Sensitivity analysis is used to examine the effects of variations in critical model parameters on net present values. Our findings indicate that waste disposal savings from application of biosolids on hybrid poplar plantations combined with incentives for landowners to sequester carbon can easily compete with agricultural land rental values in some regions of Ontario. Social acceptance of this kind of activity, however, may be an impediment to adoption.  相似文献   
573.
Marine protected areas (MPAs) provide place-based management of marine ecosystems through various degrees and types of protective actions. Habitats such as coral reefs are especially susceptible to degradation resulting from climate change, as evidenced by mass bleaching events over the past two decades. Marine ecosystems are being altered by direct effects of climate change including ocean warming, ocean acidification, rising sea level, changing circulation patterns, increasing severity of storms, and changing freshwater influxes. As impacts of climate change strengthen they may exacerbate effects of existing stressors and require new or modified management approaches; MPA networks are generally accepted as an improvement over individual MPAs to address multiple threats to the marine environment. While MPA networks are considered a potentially effective management approach for conserving marine biodiversity, they should be established in conjunction with other management strategies, such as fisheries regulations and reductions of nutrients and other forms of land-based pollution. Information about interactions between climate change and more “traditional” stressors is limited. MPA managers are faced with high levels of uncertainty about likely outcomes of management actions because climate change impacts have strong interactions with existing stressors, such as land-based sources of pollution, overfishing and destructive fishing practices, invasive species, and diseases. Management options include ameliorating existing stressors, protecting potentially resilient areas, developing networks of MPAs, and integrating climate change into MPA planning, management, and evaluation.  相似文献   
574.
Livestock production in both industrial systems, where livestock are packed tightly together, and in highly traditional systems, where a shepherd follows her herd in dispersed rangelands, are cited as key contributors in some of the most acute environmental problems around the globe. Israel is one of the few countries where both of these systems exist, with surprisingly little contact between them. The environmental impact of the sectors were examined along with Israel’s public policies in the field. While historically, much attention has been placed on the contribution of the Bedouin pastoralists to desertification and erosion, this may be linked to historic misapprehension about actual impacts of goats on local rangelands as well as political motivations and concerns about losing national sovereignty over large areas of rangelands. The true environmental effects appear to be minor. A far more critical concern is water pollution caused by the industrial sector of livestock production—an issue that recently has attracted considerable government attention and investment in a successful dairy infrastructure initiative. The divisions between governmental supports for the Jewish and Arab sectors of livestock management are inconsistent with efficient environmental management. Policies should be designed to encourage Bedouin to find ways to sustainably continue their traditional livestock husbandry practises, which today are largely associated with ecological benefits and constitute a unique cultural asset for Israel and the world.  相似文献   
575.
Nonylphenol algal bioaccumulation and its effect through the trophic chain   总被引:4,自引:0,他引:4  
Nonylphenol is a metabolic intermediate from the microbial transformation of detergents used worldwide. While nonylphenol shows some acute toxicity, it is also able to mimic important hormones resulting in the disruption of several processes by interfering with the signals that control the overall physiology of the organism. The effect of the pollutant nonylphenol (NP) through the trophic chain was studied. Microalgae Isochrysis galbana was able to bioconcentrate NP 6940 times, where 77% of initial NP (100microgl(-1)) is accumulated intracellularly after 1-h incubation. Crustacean Artemia fransiscana showed 25% higher growth when fed with NP-rich algae. However, Artemia metabolized almost all NP ingested and only traces of NP could be found in the organism, eliminating future NP effects. Zebrafish (Brachydanio rerio) were affected by the presence of 171microgg(-1) of NP in the diet, showing higher levels of the hormone vitellogenin and lower levels of cytochrome P450 activity. These results showed that organisms placed in the first level of trophic chain are able to significantly bioconcentrate the pollutant and endocrine disruptor NP. These grassed organisms affect the growth of crustacean. Moreover, the organisms placed on the top of some trophic chains, such as fish, could be affected by the presence of NP in their food, in both the hormone levels and metabolic enzymes. This work shows that the environmental presence of NP should be considered as a risk for the organisms living in an ecosystem.  相似文献   
576.
The USDA Forest Service, Forest Inventory and Analysis program (FIA) recently produced a nationwide map of forest biomass by modeling biomass collected on forest inventory plots as nonparametric functions of moderate resolution satellite data and other environmental variables using Cubist software. Efforts are underway to develop methods to enhance this initial map. We explored the possibility of modeling spatial structure to make such improvements. Spatial structure in the field biomass data as well as in residuals from the map was investigated across 18 ecological zones in the Interior Western U.S. Exploratory tools included directional graphs of summary statistics, three dimensional maps, Moran’s I correlograms, and variograms. Where spatial pattern was present, field and residual biomass were kriged, and predictions made for an independent test set were evaluated for improvement over predictions in the initial biomass map. While kriging has some potential benefit when analyzing the field data and exploring spatial structure, kriging residuals resulted in little or no improvement in the initial biomass map developed using Cubist software. Stationarity assumptions, variogram behavior, and appropriate model fitting strategies are discussed.  相似文献   
577.
Regional Environmental Change - Climate change, land use change, and sociopolitical and institutional transitions in African drylands have resulted in the loss, fragmentation, and degradation of...  相似文献   
578.
Regional Environmental Change - Protection of natural or semi-natural ecosystems is an important part of societal strategies for maintaining biodiversity, ecosystem services, and achieving overall...  相似文献   
579.
This systematic review and meta-analysis rigorously examines the relationship between glyphosate exposure and risk of lymphohematopoietic cancer (LHC) including NHL, Hodgkin lymphoma (HL), multiple myeloma (MM), and leukemia. Meta-relative risks (meta-RRs) were positive and marginally statistically significant for the association between any versus no use of glyphosate and risk of NHL (meta-RR = 1.3, 95% confidence interval (CI) = 1.0–1.6, based on six studies) and MM (meta-RR = 1.4, 95% CI = 1.0–1.9; four studies). Associations were statistically null for HL (meta-RR = 1.1, 95% CI = 0.7–1.6; two studies), leukemia (meta-RR = 1.0, 95% CI = 0.6–1.5; three studies), and NHL subtypes except B-cell lymphoma (two studies each). Bias and confounding may account for observed associations. Meta-analysis is constrained by few studies and a crude exposure metric, while the overall body of literature is methodologically limited and findings are not strong or consistent. Thus, a causal relationship has not been established between glyphosate exposure and risk of any type of LHC.  相似文献   
580.
There is a pressing need for municipalities and regions to create urban form suited to current as well as future climates, but adaptation planning uptake has been slow. This is particularly unfortunate because patterns of urban form interact with climate change in ways that can reduce, or intensify, the impact of overall global change. Uncertainty regarding the timing and magnitude of climate change is a significant barrier to implementing adaptation planning. Focusing on implementation of adaptation and phasing of policy reduces this barrier. It removes time as a decision marker, instead arguing for an initial comprehensive plan to prevent maladaptive policy choices, implemented incrementally after testing the micro-climate outcomes of previous interventions. Policies begin with no-regrets decisions that reduce the long-term need for more intensive adaptive actions and generate immediate policy benefits, while gradually enabling transformative infrastructure and design responses to increased climate impacts. Global and local indicators assume a larger role in the process, to evaluate when tipping points are in sight. We use case studies from two exemplary municipal plans to demonstrate this method's usefulness. While framed for urban planning, the approach is applicable to natural resource managers and others who must plan with uncertainty.  相似文献   
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