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Gavin Shaddick Haojie Yan Danielle Vienneau 《Environmental and Ecological Statistics》2013,20(4):553-570
Ambient concentrations of many pollutants are associated with emissions due to human activity, such as road transport and other combustion sources. In this paper we consider air pollution as a multi-level phenomenon on a continental scale within a Bayesian hierarchical model. We examine different scales of variation in pollution concentrations ranging from large scale transboundary effects to more localised effects which are directly related to human activity. Specifically, in the first stage of the model, we isolate underlying patterns in pollution concentrations due to global factors such as underlying climate and topography, which are modelled together with spatial structure. At this stage measurements from monitoring sites located within rural areas are used which, as far as possible, are chosen to reflect background concentrations. Having isolated these global effects, in the second stage we assess the effects of human activity on pollution in urban areas. The proposed model was applied to concentrations of nitrogen dioxide measured throughout the EU for which significant increases are found to be associated with human activity in urban areas. The approach proposed here provides valuable information that could be used in performing health impact assessments and to inform policy. 相似文献
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Nazli Yesiller James L. Hanson Jason T. Cox Danielle E. Noce 《Waste management (New York, N.Y.)》2014,34(5):848-858
This investigation was conducted to evaluate experimental determination of specific gravity (Gs) of municipal solid waste (MSW). Water pycnometry, typically used for testing soils was adapted for testing MSW using a large flask with 2000 mL capacity and specimens with 100–350 g masses. Tests were conducted on manufactured waste samples prepared using US waste constituent components; fresh wastes obtained prior and subsequent to compaction at an MSW landfill; and wastes obtained from various depths at the same landfill. Factors that influence specific gravity were investigated including waste particle size, compaction, and combined decomposition and stress history. The measured average specific gravities were 1.377 and 1.530 for as-prepared/uncompacted and compacted manufactured wastes, respectively; 1.072 and 1.258 for uncompacted and compacted fresh wastes, respectively; and 2.201 for old wastes. The average organic content and degree of decomposition were 77.2% and 0%, respectively for fresh wastes and 22.8% and 88.3%, respectively for old wastes. The Gs increased with decreasing particle size, compaction, and increasing waste age. For fresh wastes, reductions in particle size and compaction caused occluded intraparticle pores to be exposed and waste particles to be deformed resulting in increases in specific gravity. For old wastes, the high Gs resulted from loss of biodegradable components that have low Gs as well as potential access to previously occluded pores and deformation of particles due to both degradation processes and applied mechanical stresses. The Gs was correlated to the degree of decomposition with a linear relationship. Unlike soils, the Gs for MSW was not unique, but varied in a landfill environment due both to physical/mechanical processes and biochemical processes. Specific gravity testing is recommended to be conducted not only using representative waste composition, but also using representative compaction, stress, and degradation states. 相似文献
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M. Brasseur-Daudruy C. Garel V. Brossard F. Broux B. Heckettsweiler D. Eurin 《黑龙江环境通报》2006,26(13):1254-1255
We suggest the term ‘hyper-echogenic colon’ to describe a hyperechoic foetal colonic content with no other intestinal abnormality. This is a rare pattern, which to our knowledge, has never been correlated with a specific pathology. The accidental observation of a cystine kidney stone in an infant who presented with this sign during the prenatal period made it possible to diagnose this disease retrospectively in two other children. Copyright © 2006 John Wiley & Sons, Ltd. 相似文献
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Jacobsohn L García-España JF Durbin DR Erkoboni D Winston FK 《Journal of Safety Research》2012,43(1):21-28
IntroductionThe aim of this study was to quantify and identify correlates to the amount of parent-supervised behind-the-wheel practice hours by novice teen drivers.MethodsA national survey of 945 parents of recently licensed teen drivers was conducted. Multivariate logistic regression was used to identify factors related to the number of practice hours completed.ResultsSixty-one percent of parents reported practicing 50 or more hours with their teen. Two-parent involvement was associated with more practice hours, though use of a professional driving instructor was not. Parents of teens licensed in states mandating 50 or more hours of practice driving were more likely to report at least 50 practice hours than those in states mandating 20–40 hours or in states without mandates.Impact on IndustryThe findings underscore the integral role of parents in the learning to drive process and provide further support for GDL requirements for practice hours. 相似文献
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Brian L. Altland Danielle Cox Robert M. Enick Eric J. Beckman 《Resources, Conservation and Recycling》1995,15(3-4)
High-pressure, near-critical liquids were used as float-sink separation media for the microsortation of polyolefin mixtures and PET/PVC mixtures. Near-critical carbon dioxide was used for the refinement of the polyolefins, and sulfur hexafluoride was used to separate post-consumer PVC from PET. Preliminary experiments indicated that there was no overlap in the density ranges of post-consumer HDPE, LDPE and PP containers. There was no overlap in the PET and PVC densities, with the exception of a single PVC packaging material with a density in the PET range. These initial results indicated that a float-sink separation was a viable means of microsortation. Separations of 91% LDPE (1/8′ beads)/9% PP (1/8′ chopped strands) resin mixtures and mixed post-consumer polyolefin flakes were then conducted in a laboratory-scale, 1-I batch apparatus. This apparatus not only permitted the observation of the separation, but also enabled the separated fractions to be removed from the high-pressure environment. The results indicated that LDPE purity of greater than 98.9% was obtained in 3 min or less if (a) the fluid density was 0.018 g/cm3 greater than the PP density and only 0.002 g/cm3 less than the LDPE density, thereby providing the greatest buoyancy force for the removal of the PP, (b) the fluid was recirculated upward through the bed of mixed plastics, facilitating the upward movement of the PP, and (c) the loading was kept at levels below 40% by volume. HDPE purity of 99% was also attained with clean, dry, post-consumer mixed plastic flakes. The loadings for these separations were very low, however, due to the difficulty in agitating the mixed bed of plastics using fluid recirculation. An economic analysis of these microsortation processes indicated that the value of the sorted plastics relative to the mixed feed must increase by approx. $0.08/lb for the CO2-based separation and approx. $0.27/lb for the SF6-based separation to justify the implementation of these high-pressure processes. 相似文献
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This paper describes the conceptualization and implementation of an agent-based model to investigate how varying levels of human presence could affect elements of wolf behavior, including highway crossings; use of areas in proximity to roads and trails; size of home ranges; activities, such as hunting, patrolling, resting, and feeding pups; and survival of individuals in Banff and Kootenay National Parks, Canada. The model consists of a wolf module as the primary component with five packs represented as cognitive agents, and grizzly bear, elk, and human modules that represent dynamic components of the environment. A set of environmental data layers was used to develop a friction model that serves as a base map representing the landscape over which wolves moved. A decision model was built to simulate the sequence of wolf activities. The model was implemented in a Java Programming Language using RePast, an agent-based modeling library. Six months of wolf activities were simulated from April 16 to October 15 (i.e., a season coherent with regard to known wolf behaviors), and calibrated with GPS data from wolf radiocollars (n = 15) deployed from 2002 to 2004. Results showed that the simulated trajectories of wolf movements were correlated with the observed trajectories (Spearman's rho 0.566, P < 0.001); other critical behaviors, such as time spent at the den and not traveling were also correlated. The simulations revealed that wolf movements and behaviors were noticeably affected by the intensity of human presence. The packs’ home ranges shrank and wolves crossed highways less frequently with increased human presence. In an extreme example, a wolf pack whose home range is traversed by a high-traffic-volume highway was extirpated due to inability to hunt successfully under a scenario wherein human presence levels were increased 10-fold. The modeling prototype developed in this study may serve as a tool to test hypotheses about human effects on wolves and on other mammals, and guide decision-makers in designing management strategies that minimize impacts on wolves and on other species functionally related to wolves in the ecosystem. 相似文献