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Previous Assessments (previous + assessment)
Selected AbstractsPerformance assessment of a GCM land surface scheme using a fine-scale calibrated hydrological model: an evaluation of MOSES for the Nile BasinHYDROLOGICAL PROCESSES, Issue 11 2009Mohamed Ezzat Elshamy Abstract Land surface schemes (LSSs) represent the interface between land surface and the atmosphere in general circulation models (GCMs). Errors in LSS-simulated heat and moisture fluxes can result from inadequate representation of hydrological features and the derivation of effective surface parameters for large heterogeneous GCM gridboxes from small-scale observations. Previous assessments of LSS performance have generally compared simulated heat and moisture fluxes to observations over a defined experimental domain for a limited period. A different approach has been evaluated in this study, which uses a fine-resolution calibrated hydrological model of the study basin to provide a quasi-observed runoff series for direct comparison with simulated runoff from a selected LSS at GCM scale. The approach is tested on two GCM gridboxes covering two contrasting regions within the Nile Basin. Performance is mixed; output from the LSS is generally compatible with that of the fine-resolution model for one gridbox while it cannot reproduce the runoff dynamics for the other. The results also demonstrate the high sensitivity of runoff and evapotranspiration to radiation and precipitation inputs and show the importance of subtle issues such as temporal disaggregation of climatic inputs. We conclude that the use of a fine-resolution calibrated model to evaluate a LSS has several advantages, can be generalized to other areas to improve the performance of global models and provides useful data that can be used to constrain LSS parameterizations. Copyright © 2009 John Wiley & Sons, Ltd. [source] Bilby distribution and fire: a test of alternative models of habitat suitability in the Tanami Desert, AustraliaECOGRAPHY, Issue 6 2007Richard Southgate The distribution of the bilby Macrotis lagotis was assessed in the Tanami Desert using stratified random plots, repetitively sampled transects, aerial survey transects, and ground truth plots. Compared to a previous assessment of distribution, the extent of occurrence has changed little in the last 20 yr. However, the area of occupancy is small relative to the extent of occurrence and <25% of the current geographic range has bilby sign <20 km apart. Generalised linear modelling was used to determine the strength of association between bilby occurrence and habitat variables and identify refugia characteristics. Four competing candidate models were examined to determine whether bilby occurrence associated significantly with productive substrates and introduced herbivores, the distribution of key predator species, the pattern of fire, and climatic gradients including rainfall and temperature. For the entire study area, bilby presence associated most strongly with variables of mean annual rainfall, substrate type and the probability of dingo occurrence. Proximity to recently burnt habitat formed a significant predictor of bilby occurrence in a model derived for a reduced part of the study area where most sign was found. The work suggested that the current frameworks underpinning understanding of biotic distributions in arid Australia are deficient, and that climatic gradients, lateritic and rocky systems, and predators need to be incorporated into our thinking in the future. The extent of occurrence based on outlier records from opportunistic reports provided a misleading indication of the true status of the bilby. [source] Evaluation of the methoxytriazine herbicide prometon using a short-term fathead minnow reproduction test and a suite of in vitro bioassaysENVIRONMENTAL TOXICOLOGY & CHEMISTRY, Issue 8 2006Daniel L. Villeneuve Abstract Prometon is one of the most consistently detected herbicides in the U.S. environment. However, no previous assessment of the potential for prometon or related methoxytriazine herbicides to act as endocrine-disrupting chemicals has been conducted. This study used an array of in vitro bioassays to assess whether prometon, atraton, terbumeton, or secbumeton might act as potent (ant)agonists of the aryl hydrocarbon, estrogen, androgen, or glucocorticoid receptors or as aromatase inhibitors or inducers in vitro. Potential effects of prometon were also evaluated using a 21-d fathead minnow reproduction assay. Concentrations of methoxytriazines, as great as 1 mg/L (4.4 ,M), did not induce significant dioxin-like responses in H4IIE-luc cells, estrogenic responses in MVLN cells, or androgen or glucocorticoid receptor,mediated responses in MDA-kb2 cells, nor did the methoxytriazines significantly affect aromatase activity in vitro. In the fathead minnow assay, exposure to 20, 200, or 1,000 ,g prometon/L significantly reduced the weight of the male fat pad (an androgen-responsive tissue) relative to body weight. Exposure to 20 ,g prometon/L significantly increased female plasma testosterone concentrations, but the effect was not observed at greater concentrations. Overall, prometon did not significantly reduce fecundity over the 21-d exposure, nor were other endpoints, including plasma vitellogenin and estradiol concentrations, brain and ovary aromatase activity, and male tubercle index, significantly affected. Evidence from our work suggests that prometon may cause subtle endocrine and/or reproductive effects in fathead minnows, but no clear mechanism of action was observed. The relevance of these effects to hazard assessment for the pesticide is uncertain. [source] The Impact of Depressive Symptoms on Alcohol and Cigarette Consumption Following Treatment for Alcohol and Nicotine DependenceALCOHOLISM, Issue 1 2008Molly M. Kodl Background:, Although depression is common among alcohol and tobacco dependent patients, its impact on treatment outcomes is not well established. The purpose of this study was to examine the impact of depressive symptoms on abstinence from tobacco and alcohol after treatment for alcohol dependence and nicotine dependence. Methods:, The Timing of Alcohol and Smoking Cessation Study (TASC) randomized adults receiving intensive alcohol dependence treatment, who were also smokers, to concurrent or delayed smoking cessation treatment. The sample consisted of 462 adults who completed depression and substance use (alcohol and smoking) assessments at treatment entry and 6, 12, and 18 months posttreatment. Longitudinal regression models were used to examine the relationships between depression and subsequent abstinence from alcohol and tobacco after baseline characteristics, including alcohol and smoking histories, were considered. Results:, Depressive symptoms were prospectively related to nonabstinence from alcohol. Depressive symptoms at the previous assessment increased the odds of drinking at the subsequent time point by a factor of 1.67 (95% CI 1.14, 2.43), p < 0.01. Depressive symptoms were not significantly related to subsequent abstinence from cigarettes. Conclusions:, Depression is an important negative predictor of the ability to maintain abstinence from alcohol within the context of intensive alcoholism and smoking treatment. It may be important to include depression-specific interventions for alcohol and tobacco dependent individuals to facilitate successful drinking treatment outcomes. [source] A Geographic Information Systems,based, weights-of-evidence approach for diagnosing aquatic ecosystem impairmentENVIRONMENTAL TOXICOLOGY & CHEMISTRY, Issue 8 2006Katherine E. Kapo Abstract A Geographic Information Systems,based, watershed-level assessment using Bayesian weights of evidence (WOE) and weighted logistic regression (WLR) provides a method to determine and compare potential environmental stressors in lotic ecosystems and to create predictive models of general or species-specific biological impairment across numerous spatial scales based on limited existing sample data. The WOE/WLR technique used in the present study is a data-driven, probabilistic approach conceptualized in epidemiological research and both developed for and currently used in minerals exploration. Extrapolation of this methodology to a case-study watershed assessment of the Great and Little Miami watersheds (OH, USA) using archival data yielded baseline results consistent with previous assessments. The method additionally produced a quantitative determination of physical and chemical watershed stressor associations with biological impairment and a predicted comparative probability (i.e., favorability) of biological impairment at a spatial resolution of 0.5 km2 over the watershed study region. Habitat stressors showed the greatest spatial association with biological impairment in low-order streams (on average, 56% of total spatial association), whereas water chemistry, particularly that of wastewater effluent, was associated most strongly with biological impairment in high-order reaches (on average, 79% of total spatial association, 28% of which was attributed to effluent). Significant potential stressors varied by land-use and stream order as well as by species. This WOE/WLR method provides a highly useful "tier 1" watershed risk assessment product through the integration of various existing data sources, and it produces a clear visual communication of areas favorable for biological impairment and a quantitative ranking of candidate stressors and associated uncertainty. [source] Incentive Effects of Expanding Federal Mass Transit Formula GrantsJOURNAL OF POLICY ANALYSIS AND MANAGEMENT, Issue 2 2001Stephen Schmidt Public subsidies to industries firms incentives to alter their behavior. When calculating the effects of such programs, previous assessments of transit subsidies have not included the effects of these incentives on the firms' output. This article reports the responses of mass transit firms to the federal transit subsidy program and changes the Transportation Equity Act for the 21st Century (TEA 21) made to that program, as predicted by a structural model of output choice. TEA 21 increases bus service in medium-sized cities by 6-8 percent, butincreases service in large cities by only 1-2 percent. The formula's incentive tier is weak, and the size of the subsidy depends little on whether that output results in increased ridership. The formula could be redesigned to provide stronger incentives to lower cost and increase ridership, thus encouraging a more efficient response from transit firms. © 2001 by the Association for Public Policy Analysis and Management. [source] Transforming top-down agricultural extension to a participatory system: a study of costs and prospective benefits in EgyptPUBLIC ADMINISTRATION & DEVELOPMENT, Issue 4 2002Gerd Fleischer This article challenges some previous assessments of agricultural extension relying on simple measures of costs per farmer trained. Taking the case of Egypt, five pilot projects that aim to transform the existing agricultural extension system to a participatory system are analysed as regards their cost-effectiveness and prospective cost,benefits. It is shown that the intensity and likely impact of participatory approaches among the different projects vary. Hence, it is insufficient to judge extension programmes by their cost-effectiveness alone. In the case of cotton, for example, the costs per farmer trained are considerably lower than in horticultural crops but there are large differences in prospective benefits which would make investment in participatory extension in the latter more promising. The article calls for a more careful analysis of the costs of extension programmes in agricultural development and identifies four major cost categories, namely base costs, start-up costs, recurrent and farmers' costs. The article also submits that in the context of the debate on privatization of agricultural extension there is a role to be played for the public sector in agriculture. The success of participatory approaches to extension will depend on the quality of services provided in connection with farmer training programmes. Copyright © 2002 John Wiley & Sons, Ltd. [source] The efficacy of noncontingent reinforcement as treatment for automatically reinforced stereotypyBEHAVIORAL INTERVENTIONS, Issue 2 2002Lisa N. Britton Noncontingent reinforcement (NCR), in the form of continuous access to preferred leisure items, has recently been reported as a successful treatment for automatically reinforced aberrant behavior. However, previous research has shown that the outcome of such procedures can be compromised under certain circumstances, such as when the response effort required to access leisure items is increased. The purpose of the current study was to assess the efficacy of two variations of NCR as treatment for automatically reinforced stereotypy. In the first phase of the study, functional analyses revealed that the stereotypy of three individuals with developmental disabilities was maintained independent of social consequences. A sensory class assessment was then conducted to identify the specific sensory products that appeared to maintain the behaviors. Finally, we evaluated the effects of NCR (using stimuli identified in the previous assessments) under two conditions. In the first condition, the leisure item was made freely available, by placing it on the table in front of the participant. In the other condition, an experimenter prompted the participant to interact with the leisure item at the beginning of the session. The results indicated that NCR successfully competed with stereotypy only when participants were prompted to interact with the leisure item. These findings are discussed in the context of developing NCR interventions for automatically reinforced aberrant behavior. Copyright © 2002 John Wiley & Sons, Ltd. [source] | ||||||||||