5,487 research outputs found

    An extension and application of the Leontief pollution model for waste generation and disposal in Scotland

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    Solid waste generation, treatment and disposal are important policy concerns for the Scottish Parliament. As a result of the Environment Act 1995, a National Waste Strategy for Scotland was introduced with the general aim of reducing the amount of waste produced and dealing with what is produced in more sustainable ways. This implies the need for an empirical framework to inform policymakers regarding the relationship between economic activity and waste generation, treatment and disposal and the likely impacts of any policy actions or other disturbances on all types of sustainability indicators. In this paper we report on a study to develop an extended input-output (IO) system of the type originally proposed in the seminal paper by Leontief (1970). This involves extending the standard IOaccounts to take account of pollution or waste generation as an additional output accompanying production and consumption activities in the economy and of the activity required to clean up (or prevent) these unwanted outputs. The extension of IO tables to take account of pollution/waste generation is relatively widespread in the literature. It is usually achieved through the introduction of physical pollution/waste-output coefficients, and has been previously applied to Scotland for the case ofair pollution (see McNicoll & Blackmore, 1993, McGregor et al, 2001). Such an approach allows us to examine the impact of the economy on the environment, in terms of the amount of pollution/waste emitted as a result of economic activity. However, it does not allow us to track the feedback from the environment to the economy in terms of the resources used in environmental cleaning. If we areinterested in this aspect, we need to identify the input structure of any pollution abatement or waste disposal activities and identify columns in the IO tables representing cleaning activities

    Mental Illness in policy discourse: Locating the criminal justice system

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    Abstract presented at the Australian Political Science Association 2011 Conference, 26-28 September 2011, Canberra, Australi

    Particle Impact Analysis of Bulk Powder During Pneumatic Conveyance

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    Fragmentation of powders during transportation is a common problem for manufacturers of food and pharmaceutical products. We illustrate that the primary cause of breakage is due to inter-particle collisions, rather than particle-wall impacts, and provide a statistical mechanics model giving the number of collisions resulting in fragmentation

    Eliciting public preferences for managing the public rights of way

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    Public Rights of Way (PROW) in England and Wales, provides a wide range of social and economic benefits to those other than owners of land. The protection and extension of PROW are an important way of encouraging people to engage in informal enjoyment of urban and rural areas, with beneficial consequences for health and welfare. In urban areas they provide networks of mobility and interaction for people at the community level, helping to reduce reliance on motorised transport. In the rural context they define access to the countryside, critically linked to recreation and tourism, as well as providing mobility networks for local residents. This study describes the use of a Choice Experiment (CE) to derive monetary estimates the social benefits of PROW in an English county.Choice Experiments, Public Rights of Way, Willingness to Pay, Land Economics/Use, Resource /Energy Economics and Policy,

    Ecotoxicological characterization of biochars : role of feedstock and pyrolysis temperature

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    Seven contrasting feedstocks were subjected to slow pyrolysis at low (300 or 350 °C) and high temperature (550 or 600 °C), and both biochars and the corresponding feedstocks tested for short-term ecotoxicity using basal soil respiration and collembolan reproduction tests. After a 28-d incubation, soil basal respiration was not inhibited but stimulated by additions of feedstocks and biochars. However, variation in soil respiration was dependent on both feedstock and pyrolysis temperature. In the last case, respiration decreased with pyrolysis temperature (r = − 0.78; p < 0.0001, n = 21) and increased with a higher volatile matter content (r = 0.51; p < 0.017), these two variables being correlated (r = − 0.86, p < 0.0001). Collembolan reproduction was generally unaffected by any of the additions, but when inhibited, it was mostly influenced by feedstock, and generally without any influence of charring itself and pyrolysis temperature. Strong inhibition was only observed in uncharred food waste and resulting biochars. Inhibition effects were probably linked to high soluble Na and NH4 concentrations when both feedstocks and biochars were considered, but mostly to soluble Na when only biochars were taken into account. The general lack of toxicity of the set of slow pyrolysis biochars in this study at typical field application rates (≤ 20 Mg ha− 1) suggests a low short-term toxicity risk. At higher application rates (20-540 Mg ha− 1), some biochars affected collembolan reproduction to some extent, but only strongly in the food waste biochars. Such negative impacts were not anticipated by the criteria set in currently available biochar quality standards, pointing out the need to consider ecotoxicological criteria either explicitly or implicitly in biochar characterization schemes or in management recommendations

    Challenges of simulating undrained tests using the constant volume method in DEM

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    Liquefaction during earthquakes can cause significant infrastructural damage and loss of life, motivating a fundamental study of undrained sand response using discrete element modeling (DEM). Two methods are widely used in DEM for simulating the undrained response of soil. One approach is to numerically couple the DEM code with a fluid model. Alternatively, if the soil is fully saturated and water is assumed to be incompressible, the volume of the sample can be held constant to simulate an undrained test. The latter has the advantage of being computationally straightforward, but the assumption of a constant volume can cause some issues which are discussed in this paper. Depending on the contact model selected, extremely high deviatoric stresses and pore water pressures can be generated for dense samples using the constant volume approach which are not observed in corresponding laboratory tests. Furthermore the results of these constant volume simulations tend to be sensitive to the strain rate selected. The evolution of particle size distribution caused by grain crushing is also ignored in most undrained simulations. For these reasons, authors often restrict the extent of the data presented to physically-realistic ranges and report results in non-dimensional terms, e.g., using stress ratios (q/p’) or stresses normalized by the initial confining pressure. This paper aims to highlight some of these issues, explore whether the constant volume approach is appropriate and make recommendations for future analysis of undrained soil behavior using DEM. © 2013 AIP Publishing LLCpublished_or_final_versio

    Changes in gait during constant pace treadmill running.

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    Treadmills are often used by runners when weather conditions are adverse or a specific training effect is desired. Athletes might respond to fatigue differently when running on a treadmill compared with overground conditions, where pace is typically more variable. The purpose of this study was to measure changes in gait parameters over the course of a 10-km treadmill run. Fifteen male competitive runners ran at a constant pace for 10 km at 103% of season's best time on an instrumented treadmill with in-dwelling force plates, and data were analyzed at 5 distances. Kinematic data were derived from high-speed videography and results compared between the early and late stages. Before halfway, step length increased and cadence decreased, whereas during the latter stages, there were significant decreases in impulse and maximum force. Contact time decreased and flight time increased continually, but otherwise most gait variables did not change. The changes in contact and flight times suggested that athletes altered their gait so that more time was spent airborne to allow the treadmill to pass under them. In general, however, the runners maintained their techniques throughout the run. Constant pace treadmill running might therefore be useful with the aim of running for a particular distance and speed with a consistent technique unaffected by factors such as gradient or fatigue. However, the increase in flight time might have aided the runners because of the nature of treadmill running, and athletes and coaches should note that this training effect is impractical during overground running

    Two New Sulcate Species of Dichelonyx Harris (Coleoptera: Scarabaeidae: Melolonthinae: Dichelonychini) from Southern California, USA and Baja California, Mexico

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    © 2020 Coleopterists Society.All right reserved. Species of Dichelonyx Harris with a sulcate pronotum and from southern California, USA and Baja California, Mexico are treated in this paper. Dichelonyx magnesae McPeak and Lago, new species, and Dichelonyx bajaensis McPeak and Lago, new species, are described. The new species are illustrated, diagnostic characters to separate them from previously described species are discussed, and a key to sulcate Dichelonyx species from southern California and Baja California is presented
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