The relationship between a firm's technology and its marginal abatement cost (MAC) curve is explored. Even under the simplest specifications, the MAC curve will be kinked at some point except under a special assumption which, in reality, could easily be violated. The nondifferentiability implies that the choice of instrument under uncertainty may depend on the targeted level of emissions reduction. Also, stability conditions for dynamic tax mechanisms may be violated in the neighborhood of the kink point. A policy implication is that in some cases output restrictions are as efficient as emissions restrictions, in contrast to previous results. 相似文献
ABSTRACT: This study assesses economic and environmental impacts of uses of woody draws, small natural drainage areas covered by trees and shrubs in agricultural landscapes. Three agricultural uses and four alternative uses are evaluated. A net present value approach is used to compare economic impacts of uses of draws and APEX is used to evaluate the interaction between a woody draw and the contributing upland area and simulate the environmental impacts of uses of draws in the field. The study shows that relative to agricultural uses, alternative uses of draws have significant environmental benefits in terms of reducing surface runoff and sediment and associated pollutants, such as nitrogen, phosphorus and pesticides. Agricultural uses of draws are not always the most profitable option. Certain alternatives, such as curly willow and the mixed buffer, are highly profitable. Agricultural landscapes could be differentially managed to achieve both economic variability and environmental benefits. Government support is necessary to promote alternative uses of woody draws. The support can be in the form of CRP payments or market development of buffer products. Farmers and resource managers can use study results to manage woody draws and evaluate the merits of alternative policies for managing woody draws. 相似文献
Background: There is a need for routine estimates of injury recovery costs from pedestrian collisions using hospital separation records for economic evaluations.
Objective: To estimate the cost of injury recovery following pedestrian–vehicle collisions using the personal injury recover cost (PIRC) equation using key demographic and injury characteristics.
Method: An estimation of the costs of on-road pedestrian–vehicle collisions involving individuals who were injured and hospitalized in New South Wales (NSW), Australia, from 2002 to 2011 using the PIRC equation. The PIRC estimates individual injury recovery costs and does not include costs associated with property damage, vehicle repair, or rescue services. Individual recovery costs associated with severe traumatic brain injury (TBI) were estimated. The injured individual's mean, median, and total injury recovery costs are described for key demographic, injury, and crash characteristics.
Results: There were 9,781 pedestrians who were injured, costing an estimated total of $2.4 billion in personal injury recovery costs, an annual cost of $243 million. Males had a total injury recovery cost 1.7 times higher than females. The median injury recovery cost decreased with increasing age. TBI ($248,491) and spinal cord and vertebral column injuries ($264,103) had the highest median injury recovery costs for the body region of the most severe injury. TBI accounted for 22.6% of the total injury recovery costs for the most severe injury sustained. Just over one third of pedestrians sustained 4 or more injuries, with a median cost of $243,992, which was 1.6 times higher than the cost for a pedestrian who sustained a single injury ($153,682).
Conclusions: Personal injury recovery costs following pedestrian–vehicle collisions where a pedestrian is injured are substantial in NSW. The PIRC equation enables the economic cost burden of road traffic injury to be calculated using hospital separation data. The PIRC enables comprehensive personal injury recovery costs to be estimated and would aid in economic evaluations of preventive strategies in road safety. 相似文献
Objective: The State of Connecticut has a partial motorcycle helmet law, which has been linked to one of the lowest helmet compliance rates in the Northeast. We examine the clinical and financial impact of low motorcycle helmet use in the State of Connecticut.
Methods: A retrospective cohort study comparing the outcomes between helmeted and nonhelmeted motorcycle crash victims over a 12.5-year period, from July 2, 2002, to December 31, 2013. All patients who were admitted to the hospital after a motorcycle crash were included in the study. Patients were stratified into helmeted and nonhelmeted cohorts. Group differences were compared using t-test or Wilcoxon rank test for continuous variables and chi-square test for dichotomous outcomes. Regression models were created to evaluate predictors of helmet use, alcohol and drugs as confounding variables, and factors that influenced hospital costs.
Results: The registry included 986 eligible patients. Of this group, 335 (34%) were helmeted and 651 (66%) were nonhelmeted. Overall, nonhelmeted patients had a worse clinical presentation, with lower Glasgow Coma Scale (GCS; P <.01), higher Injury Severity Score (ISS; P <.01), higher incidence of loss of consciousness (LOC; P <.01), longer intensive care unit (ICU; P <.01) admissions, and higher incidence of head (P <.01) or face injuries (P <.01). Nonhelmeted patients were also twice as more likely to die from their injuries (P =.04, odds ratio [OR] = 1.89, 95% confidence interval [CI], 1.02–3.45). Financially, nonhelmeted patients incurred mean hospital costs of $18,458, whereas helmeted patients incurred $14,970 (P =.18). ISS, GCS, and ICU length of stay were significantly correlated with increased hospital costs (P <.01). Not using a helmet was a significant predictor of mortality (P =.04) after adjusting for alcohol/drug use and age.
Conclusions: Helmet use is associated with lower injury severity and increased survival after a motorcycle crash. These outcomes remained consistent even after controlling for age and alcohol and drug use. The medical and financial impact of Connecticut's partial helmet law should be carefully evaluated to petition for increased education and enforcement of helmet use. 相似文献
A full probabilistic Explosion Risk Analysis (ERA) is commonly used to establish overpressure exceedance curves for offshore facilities. This involves modelling a large number of gas dispersion and explosion scenarios. Capturing the time dependant build up and decay of a flammable gas cloud size along with its shape and location are important parameters that can govern the results of an ERA. Dispersion simulations using Computational Fluid Dynamics (CFD) are generally carried out in detailed ERA studies to obtain these pieces of information. However, these dispersion simulations are typically modelled with constant release rates leading to steady state results. The basic assumption used here is that the flammable gas cloud build up rate from these constant release rate dispersion simulations would mimic the actual transient cloud build up rate from a time varying release rate. This assumption does not correctly capture the physical phenomena of transient gas releases and their subsequent dispersion and may lead to very conservative results. This in turn results in potential over design of facilities with implications on time, materials and cost of a project.In the current work, an ERA methodology is proposed that uses time varying release rates as an input in the CFD dispersion simulations to obtain the fully transient flammable gas cloud build-up and decay, while ensuring the total time required to perform the ERA study is also reduced. It was found that the proposed ERA methodology leads to improved accuracy in dispersion results, steeper overpressure exceedance curves and a significant reduction in the Design Accidental Load (DAL) values whilst still maintaining some conservatism and also reducing the total time required to perform an ERA study. 相似文献