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61.
A value of statistical life (VSL) is used in cost-benefit analysis (CBA) as a monetary measure of the benefits to people from small risk reductions that arise from safety projects. Despite its widespread use in a number of countries, the concept of a VSL remains controversial, not least because it implies acceptance of the underlying ethical assumptions of CBA together with the idea that ‘social welfare’ can be measured and aggregated in some manner. In addition, to comply with theory, variable VSLs for different groups within society would be advocated. However, without fail, empirically, it is the case that those countries that employ a willingness to pay based approach to cost-benefit analysis of a safety project appraisal tend to use a single value for that accident context that is independent of the per capita income level, or indeed other personal characteristics, of the sub-group in society to which the safety improvement will actually apply. This article presents a straightforward, but theoretically justified adaptation to the calculation of a VSL which allows empirical practice by policymakers i.e. the application of a “common” VSL for any particular hazard within a given society, to be compatible with a CBA decision making approach.  相似文献   
62.
• Coulomb and Lennard−Jones forces were considered for droplet interactions. • The net droplet interactions were repulsive. • Repulsive droplet interactions increased the transport of droplets. • Repulsive droplet interactions significantly modified the fate of droplets. Previous studies reported that specially designed ventilation systems provide good air quality and safe environment by removing airborne droplets that contain viruses expelled by infected people. These water droplets can be stable in the environment and remain suspended in air for prolonged periods. Encounters between droplets may occur and droplet interactions should be considered. However, the previous studies focused on other physical phenomena (air flow, drag force, evaporation) for droplet transport and neglected droplet interactions. In this work, we used computational fluid dynamics (CFD) to simulate the transport and fate of airborne droplets expelled by an asymptomatic person and considered droplet interactions. Droplet drag with turbulence for prediction of transport and fate of droplets indicated that the turbulence increased the transport of 1 μm droplets, whereas it decreased the transport of 50 μm droplets. In contrast to only considering drag and turbulence, consideration of droplet interactions tended to increase both the transport and fate. Although the length scale of the office is much larger than the droplet sizes, the droplet interactions, which occurred at the initial stages of release when droplet separation distances were shorter, had a significant effect in droplet fate by considerably manipulating the final locations on surfaces where droplets adhered. Therefore, it is proposed that when an exact prediction of transport and fate is required, especially for high droplet concentrations, the effects of droplet interactions should not be ignored.  相似文献   
63.
Summary The social behavior of house mice captured from natural populations was studied in an enclosure. Six replicate experiments with observations totalling 344 h were done to contrast the behavior of outbreeders, individuals that have progeny by interdemic reproduction; inbreeders, individuals that have progeny by intrademic reproduction; and nonbreeders. The frequency of outbreeding was also determined.In each replicate, two male and three female commensal house mice, Mus musculus, homozygous for the same allele at the hemoglobin locus, Hbb s , were put in half of a population cage. A barrier separated this deme from another deme homozygous for the alternative allele, Hbbd. The barrier was removed after a month and each experiment continued for a further two months with daily observations.In five of six experiments, the mice from both demes formed one social group and in the sixth experiment, the mice remained in their original demes. In two experiments, outbreeding occurred: females from one deme produced offspring by males from the other deme. In three experiments, inbreeding occurred: females produced offspring by males from the same deme. Soon after the demes had formed one social group in these three experiments, the remaining male in a deme was killed and the experiment terminated; females without a male readily join other demes. The pattern of breeding resulted in a genetically effective size, N e , that was approximately half of the maximum N e obtainable with random mating. The social organization of house mice, although structured and characterized by male territoriality, presents no major barrier to gene flow within populations.Affiliative (mount, allogroom, follow) and agonistic (fight, chase, attack) behavior occurring when the barrier was present had no predictive value in determining which mice would be outbreeders. With the barrier absent, outbreeders were the recipients of more affiliative behavior than inbreeders. Male outbreeders initiated more agonistic behavior than inbreeders. Outbreeders engaged in more interdemic affiliative behavior than inbreeders.Contribution no. 362 from the Department of Ecology and Evolution at SUNY, Stony Brook  相似文献   
64.
Optical characterization of primary productivity across a coastal front   总被引:3,自引:0,他引:3  
Methods for the remote estimation of phytoplankton biomass and production rates using multiplatform sampling strategies are essential for the better understanding of oceanic bio-geochemical cycles. Recent advances in remote sensing of ocean color have made synoptic estimation of phytoplankton biomass attainable. While considerable success has been achieved in the estimation of plant biomass, the synoptic estimation of phytoplankton rates of production has been inadequate. Rapid shipboard estimates of the vertical distribution of primary productivity, on mesoscale spatial scales and event-time scales, are needed to provide both surface validation and data for the development of bio-optical models linking production to the optical characteristics of the water column. This study details the primary productivity and optical properties of a frontal region in July 1985 along 35°50N in the Southern California Bight which is shown to be consistent with the concurrent high-performance liquid-chromatography pigment-analysis. We describe here a quasi-synoptic shipboard bio-optical sampling strategy across a frontal region as an example of time-corrected data for assessing phytoplankton production in highly variable ocean regions.  相似文献   
65.
Summary Female Nuttall's White-crowned Sparrows (Zonotrichia leucophrys nuttalli) were tested in a laboratory experiment to determine their response to stimulation by songs from their natal dialect (Clear) and by songs from three different alien dialects (Fig. 1). The greatest number of copulation solicitation displays and amount of locomotor activity were caused by songs of the subject's natal dialect (Clear); the next most potent stimulus was the contiguously adjacent dialect (Buzzy); the least effective stimuli were songs from a dialect 25 km distant (McClure), representing the same non-migratory subspecies, and a dialect 1,900 km distant (Sand Creek), representing a migratory montane subspecies of White-crowned Sparrow (Figs. 2–4).These results constitute a test of a deduction made from the assortative mating theory and suggest that female White-crowned Sparrows find male song of their natal dialect sexually more stimulating. Thus, speculating about the natural circumstances, females given an unrestricted choice would be expected to mate with males from their natal dialect region.  相似文献   
66.
ABSTRACT: Hydrology is both an applied practical science and a pure geophysical science. The goal of hydrology, as a geophysical science, is to achieve theories capable of explaining with satisfactory accuracy the phenomena of interest. Through the rapidly accelerating power and versatility of digital computing technology, theory development and application are immensely facilitated via increasingly sophisticated predictive modeling schemes, which are now the principal operating tools both for applied management hydrology and for basic geophysical hydrology. While this approach treats phenomena as classes or generalizations, social and behavioral scientists have long argued that human beings base their actions on percepts, i.e., on the concrete specifics of their experience. Thus, the commonly held ideal of basing policy, decisions, and public actions on the best possible science encounters a conflict in belief systems. A possible resolution of this dilemma lies in the use of observational components, which in concept-centered science serve as data to test or calibrate models. These components also serve as a great repository of natural experience that is closely attuned to the perceptual reality that propels societal action. Landscapes and sediments provide indices of real processes, whose occurrence can be expected by continuity to extend to present and future activity. More attention to research on such indices is warranted as a means of triggering perception-based action by responsible decision-makers. Grounded in reality, and tempered by their intrinsic fallibility, the scientifically powerful conceptual schemes (models) will then serve as guides to further action. The full societal benefit of hydrological science requires a balanced approach in which subdisciplines focused on environmental indices are afforded equal attention to those focused on conceptual idealization.  相似文献   
67.
68.
The catalytic reduction of oxides of nitrogen from leaded automobile exhaust has been demonstrated to be technically feasible. These studies made with copper-containing catalysts are based upon the reducing nature of exhaust caused by the carbon monoxide present. The reaction involves 2 CO + 2 NO → + N2 + CO2 + 178.5 Kcal.  相似文献   
69.
Offset schemes help avoid or revert habitat loss through protection of existing habitat (avoided deforestation), through the restoration of degraded areas (natural regrowth), or both. The spatial scale of an offset scheme may influence which of these 2 outcomes is favored and is an important aspect of the scheme's design. However, how spatial scale influences the trade-offs between the preservation of existing habitat and restoration of degraded areas is poorly understood. We used the largest forest offset scheme in the world, which is part of the Brazilian Forest Code, to explore how implementation at different spatial scales may affect the outcome in terms of the area of avoided deforestation and area of regrowth. We employed a numerical simulation of trade between buyers (i.e., those who need to offset past deforestation) and sellers (i.e., landowners with exceeding native vegetation) in the Brazilian Amazon to estimate potential avoided deforestation and regrowth at different spatial scales of implementation. Allowing offsets over large spatial scales led to an area of avoided deforestation 12 times greater than regrowth, whereas restricting offsets to small spatial scales led to an area of regrowth twice as large as avoided deforestation. The greatest total area (avoided deforestation and regrowth combined) was conserved when the spatial scale of the scheme was small, especially in locations that were highly deforested. To maximize conservation gains from avoided deforestation and regrowth, the design of the Brazilian forest-offset scheme should focus on restricting the spatial scale in which offsets occur. Such a strategy could help ensure conservation benefits are localized and promote the recovery of degraded areas in the most threatened forest landscapes.  相似文献   
70.
Abstract

A series of mesocosms was exposed to a suite of light treatments and nutrient enrichment in order to generate algal communities of varying biomass. the influence of this biomass on the speciation of copper (II) was studied. Distribution coefficients ( Kd,Lkg?1) were relatively high (log Kd = 5 to 7), indicative of robust trace metal sequestration, and were likely controlled by the particulate organic carbon content (foc). Differences in Kd over time and among treatments were significant, as was the relationship between Kd and foc. Fluorescence quenching was used to determine binding capacities ( Lt , M) and their associated binding constants ( Kcond ,M?1) in order to model the solid phase copper speciation. the Kcond ranged between 2.1 and 5.2 × 1012M?1, indicating a very strong copper-ligand complex, and was higher in mesocosms that received more light. the light Lt increased over time, dramatically after the nutrient enrichment, but did not vary systematically among light treatments. Lt ranged from 7.2 × 10? 7 to 4.9 × 10? 5 M. the large magnitudes of Kd , Kcond and Lt ensured that greater than 97% of total copper in the mesocosms was complexed by organic matter. the total copper concentration ([Cu]T, M) needed to reach a target dissolved copper concentration of 10?12.5 M (pCu = 12.5) was determined for each mesocosm over time. [Cu]T was between 8.02 × 10?5 and 3.41 × 10?2 M, and increased over time. the [Cu]T normalized to the target pCu (Effective Dose Ratio, EDR) increased directly with increases in algal biomass, indicating a direct link between system productivity and copper exposure. Approximately 45% of the variance in EDR was explained by variance in total biomass, while the residual variance in EDR was due likely to differences in the strengths of particle associations and magnitude of binding capacities.  相似文献   
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