74 research outputs found

    Behaviour of the MgII 2798AA Line Over the Full Range of AGN Variability

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    We investigate the responsiveness of the 2798AA Mg II broad emission line in AGN on timescales of several years. Our study is based on a sample of extremely variable AGN as well as a broad population sample. The observed response of the line in previous studies has been mixed. By focussing on extreme variability (Δg>|\Delta g|> 1) we find that Mg II clearly does respond to the continuum. However, the degree of responsiveness varies strikingly from one object to another; we see cases of Mg II changing by as much as the continuum, more than the continuum, or very little at all. In 74% of the highly variable sample the behaviour of Mg II corresponds with that of Hβ\beta, with 30% of the objects showing large variations in both lines. We do not detect any change in the line width that would correspond to Broad Line Region `breathing', in accordance with results from literature. Some of the objects in our highly variable sample show a clear asymmetry in the Mg II profile. This skewness can be both to the blue and the red of the line centre. Results from our broad population sample show that highly variable quasars have lower Eddington ratios. This result holds for the variability of the continuum, but the correlation is significantly reduced for the variability of the Mg II line. For the first time, we present an overview of the value of the intrinsic Baldwin Effect for Mg II in a large sample.Comment: 22 pages, 21 figure

    Development of high strength self-compacting fibre reinforced concrete for prefabricated concrete industry

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    Prefabricated construction is an emerging industry in Australia and considered a key mechanism to boost productivity in the construction industry. The use of fibre reinforced concrete has a huge potential in the prefabricated industry as the concrete can be delivered straight to the precast mould, eliminating in many cases the steel reinforcement, thus increasing production quotas and cost savings. Such results can be further improved by utilising self-compacting concrete reinforced with fibres. Although the use of steel fibres as reinforcement is now well established, in the precast industry thin walls and shape of the moulds can be a limitation to steel fibre as well as work health and safety concerns for handling. Under such conditions, the use of polymeric fibres can be extremely beneficial, reducing labour hours and placement time as well as improving safety. This paper reports the development of high strength self-compacting fibre reinforced concrete for application in prefabricated concrete industry, exploring the effect of Forta-Ferro and ReoShore fibres on concrete fresh and mechanical properties

    Participant acceptability of digital footprint data collection strategies:an exemplar approach to participant engagement and involvement in the ALSPAC birth cohort study

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    INTRODUCTION: Digital footprint records – the tracks and traces amassed by individuals as a result of their interactions with the internet, digital devices and services – can provide ecologically valid data on individual behaviours. These could enhance longitudinal population study databanks; but few UK longitudinal studies are attempting this. When using novel sources of data, study managers must engage with participants in order to develop ethical data processing frameworks that facilitate data sharing whilst safeguarding participant interests. OBJECTIVES: This paper aims to summarise the participant involvement approach used by the ALSPAC birth cohort study to inform the development of a framework for using linked participant digital footprint data, and provide an exemplar for other data linkage infrastructures. METHODS: The paper synthesises five qualitative forms of inquiry. Thematic analysis was used to code transcripts for common themes in relation to conditions associated with the acceptability of sharing digital footprint data for longitudinal research. RESULTS: We identified six themes: participant understanding; sensitivity of location data; concerns for third parties; clarity on data granularity; mechanisms of data sharing and consent; and trustworthiness of the organisation. For cohort members to consider the sharing of digital footprint data acceptable, they require information about the value, validity and risks; control over sharing elements of the data they consider sensitive; appropriate mechanisms to authorise or object to their records being used; and trust in the organisation. CONCLUSION: Realising the potential for using digital footprint records within longitudinal research will be subject to ensuring that this use of personal data is acceptable; and that rigorously controlled population data science benefiting the public good is distinguishable from the misuse and lack of personal control of similar data within other settings. Participant co-development informs the ethical-governance framework for these novel linkages in a manner which is acceptable and does not undermine the role of the trusted data custodian

    Characterising the biophysical, economic and social impacts of soil carbon sequestration as a greenhouse gas removal technology

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    To limit warming to well below 2°C, most scenario projections rely on greenhouse gas removal technologies (GGRTs); one such GGRT uses soil carbon sequestration (SCS) in agricultural land. In addition to their role in mitigating climate change, SCS practices play a role in delivering agroecosystem resilience, climate change adaptability, and food security. Environmental heterogeneity and differences in agricultural practices challenge the practical implementation of SCS, and our analysis addresses the associated knowledge gap. Previous assessments have focused on global potentials, but there is a need among policy makers to operationalise SCS. Here, we assess a range of practices already proposed to deliver SCS, and distil these into a subset of specific measures. We provide a multi‐disciplinary summary of the barriers and potential incentives toward practical implementation of these measures. First, we identify specific practices with potential for both a positive impact on SCS at farm level, and an uptake rate compatible with global impact. These focus on: a. optimising crop primary productivity (e.g. nutrient optimisation, pH management, irrigation) b. reducing soil disturbance and managing soil physical properties (e.g. improved rotations, minimum till) c. minimising deliberate removal of C or lateral transport via erosion processes (e.g. support measures, bare fallow reduction) d. addition of C produced outside the system (e.g. organic manure amendments, biochar addition) e. provision of additional C inputs within the cropping system (e.g. agroforestry, cover cropping) We then consider economic and non‐cost barriers and incentives for land managers implementing these measures, along with the potential externalised impacts of implementation. This offers a framework and reference point for holistic assessment of the impacts of SCS. Finally, we summarise and discuss the ability of extant scientific approaches to quantify the technical potential and externalities of SCS measures, and the barriers and incentives to their implementation in global agricultural systems

    The touring reader: understanding the bibliophile's experience of literary tourism

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    This research explores the literary enthusiast’s experience of planning and undertaking literary inspired trips. The research reconceptualises the dominant figure of the literary pilgrim, inspired to visit sites associated with favourite authors, by using detailed results from 30 open-ended surveys distributed to delegates at a literary conference. The findings indicate that these keen readers prefer to plan their own trips and shun organised attractions and mainstream tourist information in favour of employing the texts themselves as source material. Respondents then feed back their experiences into the re-reading of the literary text. These findings are analysed using the concept of concretisation borrowed from literary theory. This concept, which has not been used in previous tourist studies, reflects the experience of these visitors who are using travel to solidify their reading of favourite books. This research therefore highlights the interdependence of texts and travels and emphasises the important role that imagination plays in the experience and recollection of tourist trips

    Epicosm -a framework for linking online social media in epidemiological cohorts

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    Motivation Social media represent an unrivalled opportunity for epidemiological cohorts to collect large amounts of high-resolution time course data on mental health. Equally, the high-quality data held by epidemiological cohorts could greatly benefit social media research as a source of ground truth for validating digital phenotyping algorithms. However, there is currently a lack of software for doing this in a secure and acceptable manner. We worked with cohort leaders and participants to co-design an open-source, robust and expandable software framework for gathering social media data in epidemiological cohorts. Implementation Epicosm is implemented as a Python framework that is straightforward to deploy and run inside a cohort’s data safe haven. General features The software regularly gathers Tweets from a list of accounts and stores them in a database for linking to existing cohort data. Availability This open-source software is freely available at [https://dynamicgenetics.github.io/Epicosm/]

    Artificial intelligence-supported diabetic retinopathy screening in Tanzania: rationale and design of a randomised controlled trial.

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    Globally, diabetic retinopathy (DR) is a major cause of blindness. Sub-Saharan Africa is projected to see the largest proportionate increase in the number of people living with diabetes over the next two decades. Screening for DR is recommended to prevent sight loss; however, in many low and middle-income countries, because of a lack of specialist eye care staff, current screening services for DR are not optimal. The use of artificial intelligence (AI) for DR screening, which automates the grading of retinal photographs and provides a point-of-screening result, offers an innovative potential solution to improve DR screening in Tanzania. We will test the hypothesis that AI-supported DR screening increases the proportion of persons with true referable DR who attend the central ophthalmology clinic following referral after screening in a single-masked, parallel group, individually randomised controlled trial. Participants (2364) will be randomised (1:1 ratio) to either AI-supported or the standard of care DR screening pathway. Participants allocated to the AI-supported screening pathway will receive their result followed by point-of-screening counselling immediately after retinal image capture. Participants in the standard of care arm will receive their result and counselling by phone once the retinal images have been graded in the usual way (typically after 2-4 weeks). The primary outcome is the proportion of persons with true referable DR attending the central ophthalmology clinic within 8 weeks of screening. Secondary outcomes, by trial arm, include the proportion of persons attending the central ophthalmology clinic out of all those referred, sensitivity and specificity, number of false positive referrals, acceptability and fidelity of AI-supported screening. The London School of Hygiene & Tropical Medicine, Kilimanjaro Christian Medical Centre and Tanzanian National Institute of Medical Research ethics committees have approved the trial. The results will be submitted to peer-reviewed journals for publication
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