High-resolution simulations of stellar collisions between equal-mass main-sequence stars in globular clusters

We performed high-resolution simulations of two stellar collisions relevant for stars in globular clusters. We considered one head-on collision and one off-axis collision between two 0.6 M_sun main sequence stars. We show that a resolution of about 100 000 particles is sufficient for most studies of the structure and evolution of blue stragglers. We demonstrate conclusively that collision products between main-sequence stars in globular clusters do not have surface convection zones larger than 0.004 M_sun after the collision, nor do they develop convection zones during the `pre-main-sequence' thermal relaxation phase of their post-collision evolution. Therefore, any mechanism which requires a surface convection zone (i.e. chemical mixing or angular momentum loss via a magnetic wind) cannot operate in these stars. We show that no disk of material surrounding the collision product is produced in off-axis collisions. The lack of both a convection zone and a disk proves a continuing problem for the angular momentum evolution of blue stragglers in globular clusters.Comment: 7 pages, 5 figures, accepted by MNRA

The Bull and the Red Van: Pakistani-heritage young people in a small city explore the influences upon their educational progress

This study is about the influences underlying the inequalities in educational progress experienced by Pakistani-heritage pupils in the small city of 'Newminster'. The literature offers a wealth of explanations for the persistent inequalities in attainment among different minority-ethnic groups, from which the voices of the pupils themselves are almost entirely absent. In this study, young people offer their own, often competing, explanations of distinctive aspects within the GCSE attainment data, including their rapid progress over the previous decade and the small gap in attainment between those eligible for free school meals and their peers. The principal sources of data are extended discussions with groups of Pakistani-heritage young people supplemented by interviews with parents, and a formal survey conducted by the young people among their black and minority ethnic peers. In analysing the variety of data generated by this mixed approach, the study draws up,.on the analytical framework of Bourdieu, in particular, the concept of 'habitus'. The study engages with the methodological dilemmas of a white researcher conducting research with a community to which she is an 'invited outsider', and the broader challenges of attempting 'participatory' research. The findings indicate that the Pakistani-heritage young people in the study have a strong sense of habitus that they contend has a positive influence on their educational progress. At the same time, they are actively engaged in habitus transformation. This process drives their educational aspirations but involves personal cost, dilemmas and encounters with barriers constructed by the wider education system. Their insights support a call for further consultation with marginalized young people over issues relating to their own educational progress

‘It’s a problem with the brain’: A discursive analysis of parents’ constructions of ADHD

This thesis takes a discursive approach to the talk of parents of children with an ADHD diagnosis. It uses data from 2 focus groups, 10 individual interviews and 3 mother/father interviews. The thesis adopts a synthetic approach to discourse and draws on the analytic concepts associated with both conversation analysis and with discursive approaches more concerned with the wider social context. The concepts of interpretative repertoires and subject positions are used to argue that prevalent understandings of ADHD place parents of children with ADHD at the centre of a highly moralised debate. Specifically, the prevalent psychosocial repertoire is identified as aligning ADHD with ineffective parenting. The research explores how parents talk about their experiences of ADHD, and how, through discursive action parents construct their identities in relation to ADHD. It does this, firstly, by identifying and analysing the discursive resources parents deploy in their constructions of ADHD, and their accounts of having a child with ADHD; secondly, by considering the ways in which parents manage their moral positioning in relation to their children’s ADHD diagnosis; thirdly, by identifying the cultural discourses that mothers and fathers use in the formation of their identities as ‘good’ parents. Analysis suggests that parents attend to issues of responsibility and accountability in their constructions of ADHD. ADHD can be understood as a social category which is fluid, contradictory, and imbued with a moral discourse that is linked to competing subject positions. The thesis demonstrates that parenting identities are not fixed, but are fluid and flexible depending on what is at stake. By using different discursive resources, mothers and fathers construct distinct parenting identities. Significantly, these resources often make relevant gendered subject positions, such as the valorised/blameworthy mother and the disciplining, out-at-work father. However, overall, these distinct parenting identities are formulated to convey the idea of a morally adequate and balanced parenting team

What counts as good evidence

Making better use of evidence is essential if public services are to deliver more for less. Central to this challenge is the need for a clearer understanding about standards of evidence that can be applied to the research informing social policy. This paper reviews the extent to which it is possible to reach a workable consensus on ways of identifying and labelling evidence. It does this by exploring the efforts made to date and the debates that have ensued. Throughout, the focus is on evidence that is underpinned by research, rather than other sources of evidence such as expert opinion or stakeholder views.Publisher PD

Subsurface compaction a guide for WA farmers and consultants

For plants to grow in agricultural soils, roots and emerging shoots must be able to force their way through the soil. In soils of high strength, this growth is physically restricted. High strength soils may be due to natural soil characteristics and conditions or develop as a result of agricultural practices and may be in layers or throughout the soil profile. In agriculture, high strength soils commonly occur as a result of compaction. Compaction of agricultural soils can be in the surface (often caused by stock trampling or rain drop splatter) or in the subsurface (usually in a layer at 10–40 cm). Subsurface compaction has a different suite of effects and management options than surface compaction, although, subsurface compaction amelioration techniques may also benefit a hardsetting profile. Subsurface compaction can occur in most Western Australian agricultural soils. Some soils have greater capacity to resist compaction or to self-repair following compaction. However, nearly three-quarters of WA’s agricultural soils are either affected by, or highly susceptible to, subsurface compaction (Figure 1). Compacted subsurface soil restricts crop and pasture root growth with plant biomass correspondingly reduced. In most seasons this also results in grain yield reduction. The average opportunity cost of lost agricultural production is estimated at $333 million per year for the Northern, Central, Southern and South West Agricultural regions (Herbert 2009). The most common forms of subsurface compaction in WA agricultural soils are traffic and plough hardpans caused by agricultural equipment and are the focus of this guide. In most cases these hardpans can be economically remedied and appropriate agricultural practice can minimise the reformation of hardpans.https://researchlibrary.agric.wa.gov.au/bulletins/1206/thumbnail.jp

Caution in cryptotephra correlation: resolving Lateglacial chemical controversies at Sluggan Bog, Northern Ireland

Tephra layers are valuable stratigraphic and chronological markers in palaeoenviromental studies. Establishing robust linkages require complete comparative databases of eruptive events to ensure that potential correlatives are not overlooked. This is achieved through the construction of tephrostratigraphical inventories proximal to the volcanic source. Proximally-characterised ash layers are frequently detected thousands of kilometres from source alongside limited numbers of tephras with no apparent proximal correlative. Despite the inability to correlate to a specific eruption, source volcanoes can be proposed and many of these far-field occurrences have become well-established stratigraphic markers. However, careful scrutiny is essential to verify the primary and instantaneous fallout origin of these distant occurrences. Here we present new data which proposes explanation for the long-standing controversy surrounding the source of Late-glacial age cryptotephras within Sluggan Bog, Northern Ireland. Chemical analysis of glass shards detected within this sequence are proposed to originate from an obsidian exposure located 11 km from the site, rather than from a contemporaneous eruptive event. This discovery highlights the importance of giving appropriate consideration to the enclosing geology of a particular palaeorecord. We suggest locations where geological sources might complicate air-fall recor

Missing in action? The role of the knowledge mobilisation literature in developing knowledge mobilisation practices

This project was funded by the National Institute for Health Research Health Services and Delivery Research programme (project number 11/2004/10).Despite a burgeoning literature and the development of new theories about knowledge mobilisation in the past 15 years, findings from this online survey in 2014 of over 100 research agencies (n=106; response rate 57%) show the challenges of making effective use of formal and informal learning. Many agencies rely on traditional knowledge ‘push’ activities; formal use of theoretical models and frameworks is patchy; and knowledge-sharing between agencies and the comprehensive evaluation of knowledge mobilisation programmes are limited. Closer links between research agencies, and between these and knowledge mobilisation researchers, could enhance future knowledge mobilisation practice and theory.PostprintPeer reviewe

Particle Size Estimation and Monitoring in a Bubbling Fluidized Bed Using Pressure Fluctuation Measurements

Pressure time data for binary mixtures of silica sand have been examined with particular reference to correlation between mean particle size, standard deviation and parameters obtained through attractor reconstruction techniques. The ratio of total variance to high speed variance is a particularly useful parameter for regime identification