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31.
Clearing the air: The costs and consequences of higher CAFE standards and increased gasoline taxes 总被引:4,自引:2,他引:4
Concerns about energy security and climate change have sparked legislators’ interest in reducing gasoline consumption by increasing corporate average fuel-economy (CAFE) standards. Using an empirically rich simulation model and cost estimates for anticipated fuel-economy technologies, we estimate annual costs of reducing long-run gasoline consumption by 10% via a 3.8 miles per gallon increase in the standards, and the potential cost savings from allowing manufacturers to buy and sell fuel-economy credits. Maximum gasoline savings would be realized only after all existing vehicles were replaced, or 14 years in our model. A gasoline tax would produce greater immediate savings by encouraging people to drive less, and eventually to choose more-fuel-efficient vehicles. We demonstrate the advantage of a tax by comparing the cost of the higher CAFE standards over the first 14 years against the cost of a gasoline tax that would save the same amount of gasoline over that time. 相似文献
32.
ANOVA is used to show that approximately 25% of the total variation of indoor radon concentrations in England and Wales can be explained by the mapped bedrock and superficial geology. The proportion of the total variation explained by geology is higher (up to 37%) in areas where there is strong contrast between the radon potential of sedimentary geological units and lower (14%) where the influence of confounding geological controls, such as uranium mineralisation, cut across mapped geological boundaries. When indoor radon measurements are grouped by geology and 1-km squares of the national grid, the cumulative percentage of the variation between and within mapped geological units is shown to be 34-40%. The proportion of the variation that can be attributed to mapped geological units increases with the level of detail of the digital geological data. This study confirms the importance of radon maps that show the variation of indoor radon concentrations both between and within mapped geological boundaries. 相似文献
33.
Psychiatric disorders like schizophrenia, bipolar disorder, depression, anxiety, and obsessive–compulsive disorder are common disorders with complex aetiology. They can exact a heavy toll on the individual with the condition and can have significant impact on family members too. Accordingly, psychiatric disorders can arise as a concern in the prenatal context – couples may be interested in learning about the chance for their child to develop the illness that manifests in the family and may be interested in discussing options for prenatal testing. However, the complex nature of these conditions can present challenges for clinicians who seek to help families with these issues. We established the world's first specialist genetic counselling service of its kind in Vancouver, Canada, in 2012, and to date, have provided counselling for ~500 families and have demonstrated increases in patients' empowerment and self efficacy after genetic counselling. We draw on our accumulated clinical experience to outline the process by which we approach prenatal genetic counselling for psychiatric disorders to assist other clinicians in providing thoughtful, comprehensive support to couples seeking out this service. © 2016 John Wiley & Sons, Ltd. 相似文献
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35.
Abstract Fensulfothion was incubated in nutrient media with a mixed culture of soil microorganisms obtained from sandy loam. The half life of fensulfothion in both inoculated samples and sterile controls was about 16 wk. There was some conversion to fensulfothion sulfone (16% at 6 wk) in inoculated samples, but not in the controls. Traces of fensulfothion sulfide were found in both inoculated samples (<3%) and controls (<2%) . When 1% ethanol was added to the inoculated nutrient mixture the fensulfothion disappeared rapidly (t½>~1½> wk) with 32% conversion at 20 wk to fensulfothion sulfide. 相似文献
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The most advantageous approach to pathogen destruction in a urine-diversion toilet vault is to maximize the effects of various environmental factors (i.e., pH, temperature, moisture content, type of bulking agent, and storage time). To quantify these effects, a field experiment was set up, consisting of 6 urine-diversion toilet vaults, each with a different combination of feces and bulking agent (soil, ash, wood shavings, sodium hydroxide, or straw) and ventilation (ventpipe/no ventpipe). The pH of the mixes varied from 6.37 to 10.09. Temperature probes, which were connected to a data logger, were inserted to the heaps, and the logger monitored over a period of nearly 10 months. Mean heap temperatures ranged from 16.8 degrees C in winter to 27.6 degrees C in summer. In addition, samples were taken at intervals from the various heaps in the vaults and also from an open heap exposed to the elements. The samples were subjected to microbiological testing to quantify the pathogen dieoff over time. In the vaults, there was a 3log10 (99.9%) reduction of total coliform between 130 and 250 days, fecal coliform between 100 and 250 days, and fecal streptococci from 125 days and longer. In the open heap, these times varied, from 115 days for both total and fecal coliform, to 140 days for fecal streptococci. Viable Ascaris ova were reduced to zero between 44 and 174 days in the vaults and by 44 days in the open heap. The results of this research showed that ventilation of the vault by means of a ventpipe does not result in any meaningful difference in the vault temperature or the rate of pathogen dieoff. While the type of bulking agent used does not significantly affect the temperature of the heap, it does have an effect on the rate of pathogen dieoff. The ordinary soil mix was seen to give the best results, and this was ascribed to the effect of competing microorganisms in the soil itself. It is concluded that, for safety, vaults of urine-diversion toilets should be sized for a storage period of 9 to 12 months from the last use. 相似文献
38.
Robert M. Kahn Bruce D. Smith Austin Long 《Journal of the American Water Resources Association》1996,32(3):629-635
ABSTRACT: A study of 222Rn concentrations in the water distribution system of Tucson, Arizona, revealed levels of 60 to 1260 pCi/L in domestic waters. These measurements are comparable to levels of between 80 and 1400 pCi/l for 222Rn found in ground water samples in the North-Central Tucson basin (Kahn et al., 1994). Estimated loss of 222Rn due to radioactive decay during travel from the well head to the home ranges from 8 to 50 percent. 相似文献
39.
T. Al Austin W. F. Riddle R. Q. Landers 《Journal of the American Water Resources Association》1979,15(5):1265-1280
ABSTRACT: A flood control reservoir protects valuable developments on the downstream flood plain by storing flood waters and releasing them at a rate that will reduce the downstream damage. The water surface level of the flood pool behind the dam can fluctuate considerably during the occurrence of a large magnitude flood causing severe impacts on shoreline vegetation and water based recreation facilities located in the flood pool. A mathematical simulation model describing shoreline vegetative succession in response to flooding is presented. Plant species are grouped into ecologically similar compartments. Differential equations describing compartment intrinsic growth, intraspecies competition, interspecies competition, and other growth limiting factors are solved numerically. The model is used to evaluate the impacts of various operating policies on plant succession for a new reservoir in Central Iowa. 相似文献
40.
Miles L. Burnett 《Environmental management》1998,22(2):213-224
/ In 1990, the United States officially entered the era of pollution prevention with passage of the Pollution Prevention Act. This paper analyzes EPA's implementation of the Pollution Prevention Act from its passage in 1990 to the present. It examines the barriers EPA must overcome if it is to effectively integrate pollution prevention into its existing regulatory structure, including impediments created by statutory and organizational structure, the existing relationship between EPA and the groups it regulates, the fragmented implementation scheme of national environmental regulation, the balancing of conflicting demands advanced by powerful interests, industry's economic and technical concerns, and institutional inertia. It also examines issues such as industry commitment, the limits of prevention, and measurement concerns. The findings suggest that EPA's efforts at shifting to a pollution prevention regulatory ethic that holds primacy over pollution control are mixed. Its organizational structure, statutory authority, and incentives system still reflect a single-medium pollution control focus, appropriations for pollution prevention programs and activities are paltry compared to traditional pollution control programs, and participation in the program is voluntary. Yet, the findings also point to some promising programs that are working to institutionalize a pollution prevention regulatory ethic, and many states appear very committed to the concept.KEY WORDS: Pollution prevention; Source reduction; Pollution control; Alternative regulatory design; Barriers to implementation 相似文献