The Significance of Equi-Biaxial Bubble Inflation in Determining Elastomeric Fatigue Properties

It is well documented that for the effective modelling of the static and dynamic behaviour of elastomeric components using the finite element (FE) method it is essential to obtain material parameters that are derived from a range of physical tests. For a conventional linear solid, uniaxial testing suffices to fully characterise the material, but for rubber it is necessary to test in at least two deformation modes. Also, the determination of fatigue lives of rubber components is still in its infancy and a reliable, repeatable fatigue test for rubber will have important consequences for component design, functionality, maintenance and cost. Equi-biaxial displacement has significance in FE simulations since some phenomenological models are based on even-powered strain invariants. For multi-axial deformations, which are most common for rubber components, the second strain invariant (I2) has a pronounced effect on the predicted stress-strain relationships. Also, the initiation of failures and crack propagation are very different in uniaxial and equi-biaxial load cases, so there is a proven need to obtain reliable dynamic equi-biaxial stress-strain data. Previously, the source of equi-biaxial dynamic data for rubber compounds was mainly derived from tests performed using stretch frames. These tests have numerous deficiencies that are overcome by using the bubble inflation method. Similarly, the high levels of scatter normally associated with fatigue testing of rubber are significantly ameliorated by employing this technique. An overview of fatigue life theories for elastomers is given in this text and the use of crack propagation approaches and Wöhler (S/N) curves is discussed. Dynamic physical tests and analyses of ethylene propylene diene monomer (EPDM) disc samples are described and insights into the consequences of pre-stressing samples and swelling phenomenon are also offered. The prevalence of large flaws and their influence is briefly discussed and the benefits of applying bubble inflation to characterising a range of viscoelastic phenomena in rubber are highlighted

Estimates of economic and environmental damages from tipping points cannot be reconciled with the scientific literature

Peer reviewe

Benefits Transfer and the Aquatic Environment: An Investigation into the Context of Fish Passage Improvement

We present findings from a choice experiment investigating improvements in the aquatic environment from mitigation of barriers to fish passage. Implemented at a local and national level, results reveal positive preferences for increased numbers of fish species as well as fish abundance. In addition, we examine if in this case the willingness to pay estimates are suitable for direct transfer between national and local settings. For both samples, we consider the extent to which stated attribute non-attendance impacts estimates of willingness to pay and the potential ability of researchers to transfer values between contexts. Implications of the use of benefit transfer within this policy context are discussed in light of our findings

Greening of grey infrastructure should not be used as a Trojan horse to facilitate coastal development

Climate change and coastal urbanization are driving the replacement of natural habitats with artificial structures and reclaimed land globally. These novel habitats are often poor surrogates for natural habitats. The application of integrated greening of grey infrastructure (IGGI) to artificial shorelines demonstrates how multifunctional structures can provide biodiversity benefits whilst simultaneously serving their primary engineering function. IGGI is being embraced globally, despite many knowledge gaps and limitations. It is a management tool to compensate anthropogenic impacts as part of the Mitigation Hierarchy. There is considerable scope for misuse and ‘greenwashing’ however, by making new developments appear more acceptable, thus facilitating the regulatory process. We encourage researchers to exercise caution when reporting on small-scale experimental trials. We advocate that greater attention is paid to when experiments ‘fail’ or yield unintended outcomes. We advise revisiting, repeating and expanding on experiments to test responses over broader spatio-temporal scales to improve the evidence base. Synthesis and applications. Where societal and economic demand makes development inevitable, particular attention should be paid to avoiding, minimizing and rehabilitating environmental impacts. Integrated greening of grey infrastructure (IGGI) should be implemented as partial compensation for environmental damage. Mutual benefits for both humans and nature can be achieved when IGGI is implemented retrospectively in previously developed or degraded environments. We caution, however, that any promise of net biodiversity gain from new developments should be scrutinized and any local ecological benefits set in the context of the wider environmental impacts. A ‘greened’ development will always impinge on natural systems, a reality that is much less recognized in the sea than on land.</p

Energy substitution, technical change and rebound effects

This paper investigates the relationships between energy efficiency improvements by producers, the ease of substitution between energy and other inputs and the size of the resulting “rebound effects”. Fundamentally, easier substitution leads to larger rebounds. Focusing upon conceptual and methodological issues, the paper highlights the challenges of estimating and modeling rebound effects with the help of production and cost functions and questions the robustness of the evidence base in this area. It argues that the multiple definitions of “elasticities of substitution” are a source of confusion, the most commonly estimated elasticity is of little practical value, the empirical literature is contradictory, prone to bias and difficult to use and there are only tenuous links between this literature and the assumptions used within energy-economic models. While “energy-augmenting technical change” provides the natural choice of independent variable for an estimate of rebound effects, most empirical studies do not estimate this form of technical change, many modeling studies do not simulate it and others simulate it in such a way as to underestimate rebound effects. As a result, the paper argues that current econometric and modeling studies do not provide reliable guidance on the magnitude of rebound effects in different industrial sectors

Allele mining in diverse accessions of tropical grasses to improve forage quality and reduce environmental impact

The C4Urochloa species (syn. Brachiaria) and Megathyrsus maximus (syn. Panicum maximum) are used as pasture for cattle across vast areas in tropical agriculture systems in Africa and South America. A key target for variety improvement is forage quality: enhanced digestibility could decrease the amount of land required per unit production, and enhanced lipid content could decrease methane emissions from cattle. For these traits, loss-of-function (LOF) alleles in known gene targets are predicted to improve them, making a reverse genetics approach of allele mining feasible. We therefore set out to look for such alleles in diverse accessions of Urochloa species and Megathyrsus maximus from the genebank collection held at the CIAT

Delirium detection in older acute medical inpatients: a multicentre prospective comparative diagnostic test accuracy study of the 4AT and the Confusion Assessment Method

Background:Delirium affects >15% of hospitalised patients but is grossly underdetected, contributing to poor care. The 4 ‘A’s Test (4AT; www.the4AT.com) is a short delirium assessment tool designed for routine use without special training. The primary objective was to assess the accuracy of the 4AT for delirium detection. The secondary objective was to compare the 4AT with another commonly-used delirium assessment tool, the Confusion Assessment Method (CAM).Methods:This was a prospective diagnostic test accuracy study set in Emergency Departments or acute medical wards involving acute medical patients aged >=70. All those without acutely life-threatening illness or coma were eligible. Patients underwent (1) reference standard delirium assessment based on DSM-IV criteria and (2) were randomised to either the index test (4AT, scores 0-12; prespecified score of >3 considered positive) or the comparator (CAM; scored positive or negative), in a random order, using computer-generated pseudo random numbers, stratified by study site, with block allocation. Reference standard and 4AT or CAM assessments were performed by pairs of independent raters blinded to the results of the other assessment.Results:843 individuals were randomised: 21 withdrew, 3 lost contact, 32 indeterminate diagnosis, 2 missing outcome; 785 were included in the analysis. Mean age was 81.4 (SD 6.4) years. 12.1% (95/785) had delirium by reference 1 standard assessment, 14.3% (56/392) by 4AT, and 4.7% (18/384) by CAM. The 4AT had an area under the receiver operating characteristic curve of 0.90 (95% CI 0.84-0.96). The 4AT had a sensitivity of 76% (95% CI 61-87%) and a specificity of 94% (95% CI 92-97%). The CAM had a sensitivity of 40% (95% CI 26- 57%) and a specificity of 100% (95% CI 98-100%).Conclusions:The 4AT is a short, pragmatic tool which can help improving detection rates of delirium in routine clinical care

Protocol for validation of the 4AT, a rapid screening tool for delirium: a multicentre prospective diagnostic test accuracy study

INTRODUCTION:Delirium is a severe neuropsychiatric syndrome of rapid onset, commonly precipitated by acute illness. It is common in older people in the emergency department (ED) and acute hospital, but greatly under-recognised in these and other settings. Delirium and other forms of cognitive impairment, particularly dementia, commonly coexist. There is a need for a rapid delirium screening tool that can be administered by a range of professional-level healthcare staff to patients with sensory or functional impairments in a busy clinical environment, which also incorporates general cognitive assessment. We developed the 4 'A's Test (4AT) for this purpose. This study's primary objective is to validate the 4AT against a reference standard. Secondary objectives include (1) comparing the 4AT with another widely used test (the Confusion Assessment Method (CAM)); (2) determining if the 4AT is sensitive to general cognitive impairment; (3) assessing if 4AT scores predict outcomes, including (4) a health economic analysis.METHODS AND ANALYSIS:900 patients aged 70 or over in EDs or acute general medical wards will be recruited in three sites (Edinburgh, Bradford and Sheffield) over 18 months. Each patient will undergo a reference standard delirium assessment and will be randomised to assessment with either the 4AT or the CAM. At 12 weeks, outcomes (length of stay, institutionalisation and mortality) and resource utilisation will be collected by a questionnaire and via the electronic patient record.ETHICS AND DISSEMINATION:Ethical approval was granted in Scotland and England. The study involves administering tests commonly used in clinical practice. The main ethical issues are the essential recruitment of people without capacity. Dissemination is planned via publication in high impact journals, presentation at conferences, social media and the website www.the4AT.com.TRIAL REGISTRATION NUMBER:ISRCTN53388093; Pre-results