Sustainable risk management of emerging contaminants in municipal wastewaters

This article is available open access through the publisher’s website at the link below. Copyright @ 2009 The Royal Society.The presence of emerging contaminants in municipal wastewaters, particularly endocrine-disrupting compounds such as oestrogenic substances, has been the focus of much public concern and scientific attention in recent years. Due to the scientific uncertainty still surrounding their effects, the Precautionary Principle could be invoked for the interim management of potential risks. Therefore, precautionary prevention risk-management measures could be employed to reduce human exposure to the compounds of concern. Steroid oestrogens are generally recognized as the most significant oestrogenically active substances in domestic sewage effluent. As a result, the UK Environment Agency has championed a ‘Demonstration Programme’ to investigate the potential for removal of steroid oestrogens and alkylphenol ethoxylates during sewage treatment. Ecological and human health risks are interdependent, and ecological injuries may result in increased human exposures to contaminants or other stressors. In this context of limiting exposure to potential contaminants, examining the relative contribution of various compounds and pathways should be taken into account when identifying effective risk-management measures. In addition, the explicit use of ecological objectives within the scope of the implementation of the EU Water Framework Directive poses new challenges and necessitates the development of ecosystem-based decision tools. This paper addresses some of these issues and proposes a species sensitivity distribution approach to support the decision-making process related to the need and implications of sewage treatment work upgrade as risk-management measures to the presence of oestrogenic compounds in sewage effluent

Magnetorheological landing gear: 2. Validation using experimental data

Aircraft landing gears are subjected to a wide range of excitation conditions with conflicting damping requirements. A novel solution to this problem is to implement semi-active damping using magnetorheological (MR) fluids. In part 1 of this contribution, a methodology was developed that enables the geometry of a flow mode MR valve to be optimized within the constraints of an existing passive landing gear. The device was designed to be optimal in terms of its impact performance, which was demonstrated using numerical simulations of the complete landing gear system. To perform the simulations, assumptions were made regarding some of the parameters used in the MR shock strut model. In particular, the MR fluid's yield stress, viscosity, and bulk modulus properties were not known accurately. Therefore, the present contribution aims to validate these parameters experimentally, via the manufacture and testing of an MR shock strut. The gas exponent, which is used to model the shock strut's nonlinear stiffness, is also investigated. In general, it is shown that MR fluid property data at high shear rates are required in order to accurately predict performance prior to device manufacture. Furthermore, the study illustrates how fluid compressibility can have a significant influence on the device time constant, and hence on potential control strategies

Geosynthetic landfill cap stability: comparison of limit equilibrium, computational limit analysis and finite-element analyses

The stability of the veneer cover soil (landfill cap) is an important issue in landfill design. Incorrect design of the landfill cap can lead to failure, which may result in the veneer cover soil sliding on an underlying geosynthetic layer, or in tension failure of the geosynthetic itself. Previous limit equilibrium (LE) analyses of veneer cover layer stability presented in the literature have generally considered whole-slope failure. In this paper, modified LE equations are proposed that (a) encompass more critical cases of localised slope failure for specific cases, and (b) are calibrated against two other methods: 2-D computational limit analysis (CLA) using LimitState:GEO and 2-D elasto-plastic finite-element (FE) analysis using PLAXIS. The scenarios examined encompass a cover of uniform thickness, a buttressed cover, a cover of tapered thickness, the effects of seepage forces, and the effects of construction equipment. It is shown that the LE method provides a reasonable estimate of veneer cover layer stability for most cases examined, although it is in general non-conservative, relative to the CLA and FE analyses. Local failure was found to be critical in the case of the construction equipment, buttress and horizontal seepage scenarios. In the latter case the LE equations previously presented in the literature significantly overestimate stability compared with the LE, CLA and FE analyses considered in this paper

The evolution of senescence from a comparative perspective

Summary 1. Comparative studies of ageing address the evolutionary lability of the rate of ageing as an indication of potential for, and constraints on, the extension of life span. 2. Experimental studies on ageing have focused on damage induced by reactive oxygen species (ROS) and other stresses, and on the mechanisms to prevent or repair this damage. Research on animal models has revealed genes with large effects on life span. However, the relevance of some animal models to human ageing is unclear and it is not known whether evolved differences in ageing involve such major gene effects. 3. Studies on the demography of populations of vertebrates in the wild show that animals suffer from senescence in nature. Variation in the rate of ageing is consistent with evolutionary theory in that senescence is delayed in populations that suffer relatively low extrinsic mortality. 4. Populations of longer-lived individuals suffer a higher proportion of ageing-related mortality, and thus stronger selection against early ageing. The presence of ageing-related deaths in these populations suggests a lack of suitable mechanisms that would further extend life span. 5. Similar patterns of ageing-related mortality in wild and captive or domesticated populations indicate that most ageing-related death is caused by intrinsic factors, such as tumours and cardiovascular failure, rather than increasing vulnerability to extrinsic causes of mortality. 6. Studies of several wild populations of long-lived birds suggest that ageing-related mortality is often catastrophic, with individuals maintaining high levels of condition until shortly before their demise. 7. Comparative studies of many species suggest connections between early development and the pattern of ageing later in life, consistent with laboratory studies on variation within individual species. The physiological connections across the life span are not well understood. 8. Comparative studies have provided important insights into the ageing process. However, we still lack information on important issues, including the causes of death in natural populations, the relationship of within-and between-population variation in the rate of ageing, the genetic basis of variation in rate of ageing in natural populations, and detailed longitudinal studies of individual health and reproductive success in relation to age at death

Numerical simulation of a new type of cross flow tidal turbine using OpenFOAM - Part II: Investigation of turbine-to-turbine interaction

Copyright © 2013 Elsevier. NOTICE: this is the author’s version of a work that was accepted for publication in Renewable Energy. Changes resulting from the publishing process, such as peer review, editing, corrections, structural formatting, and other quality control mechanisms may not be reflected in this document. Changes may have been made to this work since it was submitted for publication. A definitive version was subsequently published in Renewable Energy, Volume 50 (2013), DOI: 10.1016/j.renene.2012.08.064Prediction of turbine-to-turbine interaction represents a significant challenge in determining the optimized power output from a tidal stream farm, and this is an active research area. This paper presents a detailed work which examines the influence of surrounding turbines on the performance of a base case (isolated turbine). The study was conducted using a new CFD based, Immersed Body Force (IBF) model, which was validated in the first paper, and an open source CFD software package OpenFOAM was used for the simulations. The influence of the surrounding turbines was investigated using randomly chosen initial lateral and longitudinal spacing among the turbines. The initial spacing was then varied to obtain four configurations to examine the relative effect that positioning can have on the performance of the base turbine

How patients and clinicians experience the utility of a personalized clinical feedback system in routine practice

The objective was to explore how a person-adaptive clinical feedback system (CFS) effects its users, and how meaning and relevance are negotiated. We conducted a 10-month case-study of the implementation and practice of Norse Feedback, a personalized CFS. The data material consisted of 12 patient interviews, 22 clinician interviews, 23 field notes, and 16 archival documents. We identified four main categories or themes: (i) patients' use of clinical feedback for enhanced awareness and insight; (ii) patients work to make clinical feedback a communication mode; (iii) patients and clinicians negotiate clinical feedback as a way to influence treatment; and (iv) clinical feedback requires an interactive sense-making effort. Patients and therapists produced the meaning and relevance of the CFS by interpreting the CFS measures to reflect the unique patient experience of the patient-therapist relationship. Patients regarded CFS as a tool to inform therapy with important issues. Patients became more self-aware and prepared for therapy. [Abstract copyright: © 2020 The Authors. Journal of Clinical Psychology published by Wiley Periodicals LLC.

Questioning policy, youth participation and lifestyle sports

Young people have been identified as a key target group for whom participation in sport and physical activity could have important benefits to health and wellbeing and consequently have been the focus of several government policies to increase participation in the UK. Lifestyle sports represent one such strategy for encouraging and sustaining new engagements in sport and physical activity in youth groups, however, there is at present a lack of understanding of the use of these activities within policy contexts. This paper presents findings from a government initiative which sought to increase participation in sport for young people through provision of facilities for mountain biking in a forest in south-east England. Findings from qualitative research with 40 young people who participated in mountain biking at the case study location highlight the importance of non-traditional sports as a means to experience the natural environments through forms of consumption which are healthy, active and appeal to their identities. In addition, however, the paper raises questions over the accessibility of schemes for some individuals and social groups, and the ability to incorporate sports which are inherently participant-led into state-managed schemes. Lifestyle sports such as mountain biking involve distinct forms of participation which present a challenge for policy-makers who seek to create and maintain sustainable communities of youth participants

The effectiveness of metal on metal hip resurfacing: a systematic review of the available evidence published before 2002

BACKGROUND: Conventional total hip replacement (THR) may be felt to carry too high a risk of failure over a patient's lifetime, especially in young people. There is increasing interest in metal on metal hip resurfacing arthroplasty (MoM) as this offers a bone-conserving option for treating those patients who are not considered eligible for THR. We aim to evaluate the effectiveness of MoM for treatment of hip disease, and compare it with alternative treatments for hip disease offered within the UK. METHODS: A systematic review was carried out to identify the relevant literature on MoM published before 2002. As watchful waiting and total hip replacement are alternative methods commonly used to alleviate the symptoms of degenerative joint disease of the hip, we compared MoM with these. RESULTS: The data on the effectiveness of MoM are scarce, as it is a relatively new technique and at present only short-term results are available. CONCLUSION: It is not possible to make any firm conclusions about the effectiveness of MoM based on these early results. While the short-term results are promising, it is unclear if such results would be replicated in more rigorous studies, and what the long-term performance might be. Further research is needed which ideally should involve long-term randomised comparisons of MoM with alternative approaches to the clinical management of hip disease