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Distribution Approach (distribution + approach)
Selected AbstractsUncertainty analysis of single-concentration exposure data for risk assessment,introducing the species effect distribution approachENVIRONMENTAL TOXICOLOGY & CHEMISTRY, Issue 11 2006Janeck J. Scott-fordsmand Abstract In recent years, the inclusion of uncertainty analysis in risk assessment has been much debated. One pertinent issue is the translation of the effects observed with a limited number of test species to a general protection level for most or all species present in the environment. In a number of cases, toxicity data may consist of data from tests employing only a control and one treatment. Given that more species (or processes) have been tested with the same treatment, the treatment can be considered as fixed, and the effect level of the individual species (or processes) can be considered as variable. The distribution of effects can be viewed as a species effect distribution for that treatment. The distribution will represent all organisms and may be used to predict the maximum impact on any fraction of all organisms (e.g., 95% of all species). Hence, it is possible to predict the maximum effect level, with a selected certainty, for a given fraction of all species. [source] Approaches for derivation of environmental quality criteria for substances applied in risk assessment of discharges from offshore drilling operationsINTEGRATED ENVIRONMENTAL ASSESSMENT AND MANAGEMENT, Issue 2 2008Dag Altin Abstract In order to achieve the offshore petroleum industries "zero harm" goal to the environment, the environmental impact factor for drilling discharges was developed as a tool to identify and quantify the environmental risks associated with disposal of drilling discharges to the marine environment. As an initial step in this work the main categories of substances associated with drilling discharges and assumed to contribute to toxic or nontoxic stress were identified and evaluated for inclusion in the risk assessment. The selection were based on the known toxicological properties of the substances, or the total amount discharged together with their potential for accumulation in the water column or sediments to levels that could be expected to cause toxic or nontoxic stress to the biota. Based on these criteria 3 categories of chemicals were identified for risk assessment the water column and sediments: Natural organic substances, metals, and drilling fluid chemicals. Several approaches for deriving the environmentally safe threshold concentrations as predicted no effect concentrations were evaluated in the process. For the water column consensus were reached for using the species sensitivity distribution approach for metals and the assessment factor approach for natural organic substances and added drilling chemicals. For the sediments the equilibrium partitioning approach was selected for all three categories of chemicals. The theoretically derived sediment quality criteria were compared to field-derived threshold effect values based on statistical approaches applied on sediment monitoring data from the Norwegian Continental Shelf. The basis for derivation of predicted no effect concentration values for drilling discharges should be consistent with the principles of environmental risk assessment as described in the Technical Guidance Document on Risk Assessment issued by the European Union. [source] Implementing loss distribution approach for operational riskAPPLIED STOCHASTIC MODELS IN BUSINESS AND INDUSTRY, Issue 3 2010Pavel V. ShevchenkoArticle first published online: 21 OCT 200 Abstract In order to quantify the operational risk capital charge under the current regulatory framework for banking supervision, referred to as Basel II, many banks adopt the loss distribution approach. There are many modeling issues that should be resolved to use this approach in practice. In this paper we review the quantitative methods suggested in the literature for the implementation of the approach. In particular, the use of Bayesian inference that allows one to take expert judgement and parameter uncertainty into account, modeling dependence, and inclusion of insurance are discussed. Copyright © 2009 John Wiley & Sons, Ltd. [source] What have We Learnt from the Convergence Debate?JOURNAL OF ECONOMIC SURVEYS, Issue 3 2003Nazrul Islam This paper surveys the convergence literature. It begins by laying out different definitions of convergence and by showing the link between the convergence issue and the growth theory debate. The paper then follows the convergence research conducted along four different approaches, namely the cross-section, panel, time-series, and distribution approaches. The paper shows the association of these methodological approaches with various definitions of convergence and highlights the connections among the convergence results. It shows that, despite some impressions to the contrary, there is considerable agreement among the results. Although the convergence research might not have solved the growth debate entirely, it has helped both the neoclassical and the new growth theories to adapt and evolve. The research on convergence has established new stylized facts regarding cross-country growth regularities. It has brought to fore the existence of large technological and institutional differences across countries and has given rise to new methodologies for quantifying and analyzing these differences. This is providing a new information base for analysis of technological and institutional diffusion and for further development of growth theory in general. [source] Size distribution approaches for monitoring and conservation of coastal Cymodocea habitatsAQUATIC CONSERVATION: MARINE AND FRESHWATER ECOSYSTEMS, Issue 2 2010S. Orfanidis Abstract 1.Cymodocea nodosa's leaf length distribution was studied as an easily measurable indicator to monitor and conserve Macedonian, North Aegean, Greek coastal habitats. 2.Three Cymodocea meadows off the eastern Kavala Gulf coast (Nea Karvali, Erateino, Agiasma), with that of Nea Karvali close to an industrial area being the most degraded, were sampled during the seagrass main growing season in July 2004. Two further meadows, one pristine to less degraded (Brasidas, Gulf of Kavala) and one degraded (Biamyl, Inner Thessaloniki Gulf), were sampled as benchmarks in July 2005. The results were evaluated using Gaussian fit curves, and non-parametric and nested parametric ANOVA on a hierarchy of spatial scales: area (tens of metres), site (hundreds of metres) and meadow (kilometres). 3.Frequency (%) distribution of leaf length values and CymoSkew index variation were best associated with anthropogenic stress. Frequency (%) distribution of adult and intermediate photosynthetic leaf length values revealed a unimodal distribution possible to be fitted, at least at pristine to less degraded meadows, by normal distribution (R2>0.5). 4.Statistically significant variation was estimated for CymoSkew index, a quantitative expression of leaf length asymmetry, on the meadow scale (P<0.001). Biamyl (3.82) and Nea Karvali (3.64) were indicated as heavily degraded meadows, Erateino (2.93) as a degraded meadow, Agiasma (2.18) as a meadow with the first signs of degradation, and Brasidas (1.68) as a pristine to less degraded meadow. These results in combination with other meadow specific biotic parameters were used to suggest a preliminary angiosperm ,Ecological Status Classes' classification scheme useful for the implementation of WFD in the north Aegean Sea. 5.The CymoSkew index seems to respond to lower levels of stress than is needed for other more conservative plant modules and therefore, could be regarded as an early warning indicator of Cymodocea habitat degradation. Copyright © 2009 John Wiley & Sons, Ltd. [source] | ||||||||||