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401.
When the cold war ended, the United States stopped developing,testing and building nuclear weapons at nearly all of its former nuclear weapon sites. The Department of Energy (DoE) began a massive environmental remediation programme, which includes engaging surrounding communities in a future land use planning process. Using the Savannah River site as an example, we show that this process faces large obstacles, especially a legacy of mistrust of the DoE and organizational limitations at the federal and local government scales. These hinder open dialogue about future land use. The authors suggest three planning principles for future land use planning and organizational issues that must be addressed before these can be fruitfully explored.  相似文献   
402.
Increased job complexity and autonomy have often been associated with improved performance in work groups. This study examines the mediating effect of group cohesiveness. The moderating effects of individualism/collectivism on the relationship between job characteristics (both complexity and autonomy) and cohesiveness are also tested. The sample consists of 381 teams drawn from the Hong Kong and U.S. branches of an international bank. The findings indicate that an increase in job complexity and/or task autonomy will increase group cohesiveness, which subsequently translates to better performance. The positive effects of job complexity and autonomy on group cohesiveness are also found to be more prominent for individualistic rather than collectivistic work groups. The theoretical implications of the results and the limitations of the study are also discussed. Copyright © 2003 John Wiley & Sons, Ltd.  相似文献   
403.
Congenital heart defects occur in approximately 1% of liveborn children and represent the most common form of congenital malformation. Due to the small size and complexity of the heart structures, prenatal diagnosis is most often made in the second trimester of pregnancy. Early diagnosis however offers significant advantages regarding the timing of further investigations, prenatal counseling, and access to management options. In the last decade, advances in antenatal imaging have improved the detection of cardiac malformations with increasing emphasis on earlier pregnancy screening and diagnosis. We aim to summarize current “state of the art” imaging of the fetal heart in the first trimester.  相似文献   
404.
Biodiversity indicators are used to inform decisions and measure progress toward global targets, such as the United Nations Sustainable Development Goals. Indicators aggregate and simplify complex information, so underlying information influencing its reliability and interpretation (e.g., variability in data and uncertainty in indicator values) can be lost. Communicating uncertainty is necessary to ensure robust decisions and limit misinterpretations of trends, yet variability and uncertainty are rarely quantified in biodiversity indicators. We developed a guide to representing uncertainty and variability in biodiversity indicators. We considered the key purposes of biodiversity indicators and commonly used methods for representing uncertainty (standard error, bootstrap resampling, and jackknife resampling) and variability (quantiles, standard deviation, median absolute deviation, and mean absolute deviation) with intervals. Using 3 high-profile biodiversity indicators (Red List Index, Living Planet Index, and Ocean Health Index), we tested the use, suitability, and interpretation of each interval method based on the formulation and data types underpinning the indicators. The methods revealed vastly different information; indicator formula and data distribution affected the suitability of each interval method. Because the data underpinning each indicator were not normally distributed, methods relying on normality or symmetrical spread were unsuitable. Quantiles, bootstrapping, and jackknifing provided useful information about the underlying variability and uncertainty. We built a decision tree to inform selection of the appropriate interval method to represent uncertainty or variation in biodiversity indicators, depending on data type and objectives. Our guide supports transparent and effective communication of biodiversity indicator trends to facilitate accurate interpretation by decision makers.  相似文献   
405.
406.
We developed a method to estimate population abundance from simultaneous counts of unmarked individuals over multiple sites. We considered that at each sampling occasion, individuals in a population could be detected at 1 of the survey sites or remain undetected and used either multinomial or binomial simultaneous-count models to estimate abundance, the latter being equivalent to an N-mixture model with one site. We tested model performance with simulations over a range of detection probabilities, population sizes, growth rates, number of years, sampling occasions, and sites. We then applied our method to 3 critically endangered vulture species in Cambodia to demonstrate the real-world applicability of the model and to provide the first abundance estimates for these species in Cambodia. Our new approach works best when existing methods are expected to perform poorly (i.e., few sites and large variation in abundance among sites) and if individuals may move among sites between sampling occasions. The approach performed better when there were >8 sampling occasions and net probability of detection was high (>0.5). We believe our approach will be useful in particular for simultaneous surveys at aggregation sites, such as roosts. The method complements existing approaches for estimating abundance of unmarked individuals and is the first method designed specifically for simultaneous counts.  相似文献   
407.
Sixty leading members of the scientific, engineering, regulatory, and legal communities assembled for the PFAS Experts Symposium in Arlington, Virginia on May 20 and 21, 2019 to discuss issues related to per‐ and polyfluoroalkyl substances (PFAS) based on the quickly evolving developments of PFAS regulations, chemistry and analytics, transport and fate concepts, toxicology, and remediation technologies.  The Symposium created a venue for experts with various specialized skills to provide opinions and trade perspectives on existing and new approaches to PFAS assessment and remediation in light of lessons learned managing other contaminants encountered over the past four decades. The following summarizes several consensus points developed as an outcome of the Symposium:
  • Regulatory and policy issues: The response by many states and the US Environmental Protection Agency (USEPA) to media exposure and public pressure related to PFAS contamination is to relatively quickly initiate programs to regulate PFAS sites. This includes the USEPA establishing relatively low lifetime health advisory levels for PFAS in drinking water and even more stringent guidance and standards in several states. In addition, if PFAS are designated as hazardous substances at the federal level, as proposed by several Congressional bills, there could be wide‐reaching effects including listing of new Superfund sites solely for PFAS, application of stringent state standards, additional characterization and remediation at existing sites, reopening of closed sites, and cost renegotiation among PRPs.
  • Chemistry and analytics: PFAS analysis is confounded by the lack of regulatory‐approved methods for most PFAS in water and all PFAS in solid media and air, interference with current water‐based analytical methods if samples contain high levels of suspended solids, and sample collection and analytical interference due to the presence of PFAS in common consumer products, sampling equipment, and laboratory materials.
  • Toxicology and risk: Uncertainties remain related to human health and ecological effects for most PFAS; however, regulatory standards and guidance are being established incorporating safety factors that result in part per trillion (ppt) cleanup objectives. Given the thousands of PFAS that may be present in the environment, a more appropriate paradigm may be to develop toxicity criteria for groups of PFAS rather than individual PFAS.
  • Transport and fate: The recalcitrance of many perfluoroalkyl compounds and the capability of some fluorotelomers to transform into perfluoroalkyl compounds complicate conceptual site models at many PFAS sites, particularly those involving complex mixtures, such as firefighting foams. Research is warranted to better understand the physicochemical properties and corresponding transport and fate of most PFAS, of branched and linear isomers of the same compounds, and of the interactions of PFAS with other co‐contaminants such as nonaqueous phase liquids. Many PFAS exhibit complex transport mechanisms, particularly at the air/water interface, and it is uncertain whether traditional transport principles apply to the ppt levels important to PFAS projects. Existing analytical methods are sufficient when combined with the many advances in site characterization techniques to move rapidly forward at selected sites to develop and test process‐based conceptual site models.
  • Existing remediation technologies and research: Current technologies largely focus on separation (sorption, ion exchange, or sequestration). Due to diversity in PFAS properties, effective treatment will likely require treatment trains. Monitored natural attenuation will not likely involve destructive reactions, but be driven by processes such as matrix diffusion, sorption, dispersion, and dilution.
The consensus message from the Symposium participants is that PFAS present far more complex challenges to the environmental community than prior contaminants. This is because, in contrast to chlorinated solvents, PFAS are severely complicated by their mobility, persistence, toxicological uncertainties, and technical obstacles to remediation—all under the backdrop of stringent regulatory and policy developments that vary by state and will be further driven by USEPA. Concern was expressed about the time, expense, and complexity required to remediate PFAS sites and whether the challenges of PFAS warrant alternative approaches to site cleanups, including the notion that adaptive management and technical impracticability waivers may be warranted at sites with expansive PFAS plumes. A paradigm shift towards receptor protection rather than broad scale groundwater/aquifer remediation may be appropriate.  相似文献   
408.

Purse seine fishing of skipjack tuna in the Western and Central Pacific Ocean (WCPO) raises concern over increasing impacts on yellowfin and bigeye tuna by-catch. To address sustainability concerns, the Parties to the Nauru Agreement (PNA) adopted the vessel day scheme (VDS) for the management of purse seine fishing in the WCPO. The VDS has the potential to improve economic benefits for PNA members and to contribute to sustainability of the tuna stocks, and since 2012, has become an important mechanism to regulate fishing access rights in PNA waters. Despite this, monitoring and enforcement remains weak leading to violations of the agreement. Using a game theoretic framework, this paper examines the effectiveness of the VDS and its implications for fisheries regionalism. We examine the payoffs of member countries of the Nauru Agreement under full compliance and payoffs under the currently observed partial compliance. Our findings indicate that member states’ partial compliance with VDS rules plays a role in stabilising the agreement. Requiring full compliance, on the other hand, may encompass strong incentives for PNA members to deviate from the VDS since third parties offer attractive benefits in return for privileged access to fishing grounds. However, pragmatic tolerance of deviations from full VDS compliance seems to play a facilitative role in promoting cooperation and fisheries regionalism.

  相似文献   
409.
There is currently a considerable emphasis on delivering major renewable energy infrastructure projects. Such projects will have impacts on local communities; some impacts may be perceived as positive but others will be viewed more negatively. Any just regulatory process for considering and permitting such infrastructure will need to heed the concerns that local communities voice. But what counts as a local voice? In this paper it is argued that the regulatory process plays a performative role, constructing what counts as a local voice. Furthermore, this has consequences for how regulatory deliberations proceed and the outcomes of regulatory processes. The empirical basis for this argument is a study of major offshore renewable energy infrastructure in England and Wales and the way that it is regulated through a specific regime – the Nationally Significant Infrastructure Projects (NSIPs) regime established by the Planning Act 2008. Through a detailed study of eight projects that have passed through the regime, the analysis unfolds the way that the voices of local residents, local businesses, local NGOs and local authorities are constructed in the key boundary object of the Examining Authority’s report; it then draws out the implications for the mitigation measures that are negotiated. The research suggests that what counts as a local voice is constrained by how the performative role of the NSIPs regulatory regime differentiates between interests and suggests that new ways of giving voice to local people are required.  相似文献   
410.
The field of biodiversity conservation has recently been criticized as relying on a fixist view of the living world in which existing species constitute at the same time targets of conservation efforts and static states of reference, which is in apparent disagreement with evolutionary dynamics. We reviewed the prominent role of species as conservation units and the common benchmark approach to conservation that aims to use past biodiversity as a reference to conserve current biodiversity. We found that the species approach is justified by the discrepancy between the time scales of macroevolution and human influence and that biodiversity benchmarks are based on reference processes rather than fixed reference states. Overall, we argue that the ethical and theoretical frameworks underlying conservation research are based on macroevolutionary processes, such as extinction dynamics. Current species, phylogenetic, community, and functional conservation approaches constitute short‐term responses to short‐term human effects on these reference processes, and these approaches are consistent with evolutionary principles.  相似文献   
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