2,259 research outputs found

    Life-course and cohort trajectories of mental health in the UK, 1991–2008 – A multilevel age–period–cohort analysis

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    There is ongoing debate regarding the shape of life-course trajectories in mental health. Many argue the relationship is U-shaped, with mental health declining with age to mid-life, then improving. However, I argue that these models are beset by the age–period–cohort (APC) identification problem, whereby age, cohort and year of measurement are exactly collinear and their effects cannot be meaningfully separated. This means an apparent life-course effect could be explained by cohorts. This paper critiques two sets of literature: the substantive literature regarding life-course trajectories in mental health, and the methodological literature that claims erroneously to have ‘solved’ the APC identification problem statistically (e.g. using Yang and Land's Hierarchical APC–HAPC-model). I then use a variant of the HAPC model, making strong but justified assumptions that allow the modelling of life-course trajectories in mental health (measured by the General Health Questionnaire) net of any cohort effects, using data from the British Household Panel Survey, 1991–2008. The model additionally employs a complex multilevel structure that allows the relative importance of spatial (households, local authority districts) and temporal (periods, cohorts) levels to be assessed. Mental health is found to increase throughout the life-course; this slows at mid-life before worsening again into old age, but there is no evidence of a U-shape – I argue that such findings result from confounding with cohort processes (whereby more recent cohorts have generally worse mental health). Other covariates were also evaluated; income, smoking, education, social class, urbanity, ethnicity, gender and marriage were all related to mental health, with the latter two in particular affecting life-course and cohort trajectories. The paper shows the importance of understanding APC in life-course research generally, and mental health research in particular

    Turbulence-chemistry interaction in lean premixed hydrogen combustion

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    This paper presents three-dimensional direct numerical simulations of lean premixed hydrogen flames at an equivalence ratio of varphi=0.4 over a range of turbulence levels from Ka=1 - 36. The simulations form part of a larger effort to construct a DNS database that can be used by the community for model construction and validation. We have focussed on producing well-resolved simulations at conditions representative of atmospheric laboratory-scale flames. After an overview of phenomenological trends with increasing Karlovitz number, we examine the factors that lead to an observed decorrelation between fuel consumption and heat release in the flame at Ka=36. We show that in this flame the fuel consumption is greatly enhanced in regions of positive curvature. We also show that the radical pool is enriched throughout the entire flame as \Ka is increased. In particular, we identify three reactions that, driven by high molar concentrations of radicals at low temperatures, are responsible for high levels of heat release away from regions of fuel consumption, thereby accounting for the observed decorrelation between fuel consumption and heat release

    Addressing the clumsiness loophole in a Leggett-Garg test of macrorealism

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    The rise of quantum information theory has lent new relevance to experimental tests for non-classicality, particularly in controversial cases such as adiabatic quantum computing superconducting circuits. The Leggett-Garg inequality is a "Bell inequality in time" designed to indicate whether a single quantum system behaves in a macrorealistic fashion. Unfortunately, a violation of the inequality can only show that the system is either (i) non-macrorealistic or (ii) macrorealistic but subjected to a measurement technique that happens to disturb the system. The "clumsiness" loophole (ii) provides reliable refuge for the stubborn macrorealist, who can invoke it to brand recent experimental and theoretical work on the Leggett-Garg test inconclusive. Here, we present a revised Leggett-Garg protocol that permits one to conclude that a system is either (i) non-macrorealistic or (ii) macrorealistic but with the property that two seemingly non-invasive measurements can somehow collude and strongly disturb the system. By providing an explicit check of the invasiveness of the measurements, the protocol replaces the clumsiness loophole with a significantly smaller "collusion" loophole.Comment: 7 pages, 3 figure

    Pre‐service teacher training and special educational needs in England 1970–2008: is government learning the lessons of the past or is it experiencing a groundhog day?

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    The paper outlines the findings from a literature review of the English government’s response to the issue of training pre‐service teachers in the delivery of effective special educational needs support. The review’s findings detail that although educational practice in mainstream classrooms has changed considerably since the 1970s the training of pre‐service teachers with regards to special educational needs has seemingly changed very little. The paper argues that the government needs to re‐think radically its policy of inclusion to ensure that a coherent plan is formulated which enables higher education institutions’ initial teacher training programmes to train students who are competent and confident in their abilities to work with children with special educational needs and/or disabilities

    Charm Quark Contribution to K+ -> pi+ nu anti-nu at Next-to-Next-to-Leading Order

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    We calculate the complete NNLO QCD corrections to the charm contribution of the rare decay K+ -> pi+ nu nu-bar. We encounter several new features, which were absent in lower orders. We discuss them in detail and present the results for the 2-loop matching conditions of the Wilson coefficients, the 3-loop anomalous dimensions, and the 2-loop matrix elements of the relevant operators that enter the NNLO renormalization group analysis of the Z-penguin and the electroweak box contribution. The inclusion of the NNLO QCD corrections leads to a significant reduction of the theoretical uncertainty from 9.8% down to 2.4% in the relevant parameter Pc, implying the leftover scale uncertainties in BR(K+ -> pi+ nu nu-bar) and in the determination of |V_td|, sin(2 beta), and gamma from the K -> pi nu nu system to be 1.3%, 1.0%, 0.006, and 1.2 degrees, respectively. For the charm quark MSbar mass mc=(1.30+-0.05) GeV and |V_us|= 0.2248 the NLO value Pc=0.37+-0.06 is modified to Pc=0.38+-0.04 at the NNLO level with the latter error fully dominated by the uncertainty in mc. We present tables for Pc as a function of mc and alphas(MZ) and a very accurate analytic formula that summarizes these two dependences as well as the dominant theoretical uncertainties. Adding the recently calculated long-distance contributions we find BR(K+ -> pi+ nu nu-bar)=(8.0+-1.1)*10^-11 with the present uncertainties in mc and the Cabibbo-Kobayashi-Maskawa elements being the dominant individual sources in the quoted error. We also emphasize that improved calculations of the long-distance contributions to K+ -> pi+ nu nu-bar and of the isospin breaking corrections in the evaluation of the weak current matrix elements from K+ -> pi0 e+ nu would be valuable in order to increase the potential of the two golden K -> pi nu nu decays in the search for new physics.Comment: 74 pages, 28 figures. Erratum added: We correct the treatment of anomalous triangle diagrams. The associated numerical correction is below a permille; v3: Typographical mistakes in (108), (111) and (112) corrected. Thanks to Xu Feng for pointing them out. Numerical results unchange

    The increasing activity of a vascular ultrasound service

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    Objectives:To examine the change in activity of a vascular ultrasound service over 7 years.Design:Retrospective review.Setting:Vascular studies unit, University hospital.Method:Audit of the number of vascular ultrasound tests carried out over the last 7 years using a prospective computerised database.Results:Data shows that the overall workload has tripled over the 7-year period. In addition the complexity of investigations has increased during this time. The number of carotid scans has increased four-fold while the number of graft surveillance scans and vein scans has increased seven-fold. Assessment of lower limb arteries has developed from simple pressure measurements to detailed ultrasound scans and, as a consequence, the number of diagnostic angiograms has fallen by 75%. The factors that have influenced these changes are discussed.Conclusion:There has been an important increase in the role of colour Doppler ultrasound as it becomes the “first line” vascular diagnostic test. However this trend can only continue if vascular ultrasound services are appropriately resourced. It is therefore essential to maintain an efficient audit system

    Real-time PCR based on SYBR-Green I fluorescence: An alternative to the TaqMan assay for a relative quantification of gene rearrangements, gene amplifications and micro gene deletions

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    BACKGROUND: Real-time PCR is increasingly being adopted for RNA quantification and genetic analysis. At present the most popular real-time PCR assay is based on the hybridisation of a dual-labelled probe to the PCR product, and the development of a signal by loss of fluorescence quenching as PCR degrades the probe. Though this so-called 'TaqMan' approach has proved easy to optimise in practice, the dual-labelled probes are relatively expensive. RESULTS: We have designed a new assay based on SYBR-Green I binding that is quick, reliable, easily optimised and compares well with the published assay. Here we demonstrate its general applicability by measuring copy number in three different genetic contexts; the quantification of a gene rearrangement (T-cell receptor excision circles (TREC) in peripheral blood mononuclear cells); the detection and quantification of GLI, MYC-C and MYC-N gene amplification in cell lines and cancer biopsies; and detection of deletions in the OPA1 gene in dominant optic atrophy. CONCLUSION: Our assay has important clinical applications, providing accurate diagnostic results in less time, from less biopsy material and at less cost than assays currently employed such as FISH or Southern blotting

    Leionema lamprophyllum subsp. fractum (Rutaceae); a new and highly restricted taxon from the Hunter Valley of New South Wales

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    A new subspecies of Leionema lamprophyllum, formerly included in L. lamprophyllum subsp. obovatum F.M.Anderson, is here described as new. Currently known from fewer than 50 individuals, the new subsp. is highly restricted and warrants a conservation risk code of at least Endangered. An illustration of the new taxon, notes on its distribution and habitat, and a key to all four subspecies of L. lamprophyllum are also provided
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