626 research outputs found

    The stellar and sub-stellar IMF of simple and composite populations

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    The current knowledge on the stellar IMF is documented. It appears to become top-heavy when the star-formation rate density surpasses about 0.1Msun/(yr pc^3) on a pc scale and it may become increasingly bottom-heavy with increasing metallicity and in increasingly massive early-type galaxies. It declines quite steeply below about 0.07Msun with brown dwarfs (BDs) and very low mass stars having their own IMF. The most massive star of mass mmax formed in an embedded cluster with stellar mass Mecl correlates strongly with Mecl being a result of gravitation-driven but resource-limited growth and fragmentation induced starvation. There is no convincing evidence whatsoever that massive stars do form in isolation. Various methods of discretising a stellar population are introduced: optimal sampling leads to a mass distribution that perfectly represents the exact form of the desired IMF and the mmax-to-Mecl relation, while random sampling results in statistical variations of the shape of the IMF. The observed mmax-to-Mecl correlation and the small spread of IMF power-law indices together suggest that optimally sampling the IMF may be the more realistic description of star formation than random sampling from a universal IMF with a constant upper mass limit. Composite populations on galaxy scales, which are formed from many pc scale star formation events, need to be described by the integrated galactic IMF. This IGIMF varies systematically from top-light to top-heavy in dependence of galaxy type and star formation rate, with dramatic implications for theories of galaxy formation and evolution.Comment: 167 pages, 37 figures, 3 tables, published in Stellar Systems and Galactic Structure, Vol.5, Springer. This revised version is consistent with the published version and includes additional references and minor additions to the text as well as a recomputed Table 1. ISBN 978-90-481-8817-

    Predictors of tuberculosis (TB) and antiretroviral (ARV) medication non-adherence in public primary care patients in South Africa: A cross sectional study

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    Background: Despite the downward trend in the absolute number of tuberculosis (TB) cases since 2006 and the fall in the incidence rates since 2001, the burden of disease caused by TB remains a global health challenge. The co-infection between TB and HIV adds to this disease burden. TB is completely curable through the intake of a strict anti-TB drug treatment regimen which requires an extremely high and consistent level of adherence.The aim of this study was to investigate factors associated with adherence to anti-TB and HIV treatment drugs. Methods: A cross-sectional survey method was used. Three study districts (14 primary health care facilities in each) were selected on the basis of the highest TB caseload per clinic. All new TB and new TB retreatment patients were consecutively screened within one month of anti-tuberculosis treatment. The sample comprised of 3107 TB patients who had been on treatment for at least three weeks and a sub-sample of the total sample were on both anti-TB treatment and anti-retro-viral therapy(ART) (N = 757). Data collection tools included: a Socio-Demographic Questionnaire; a Post-Traumatic-Stress-Disorder (PTSD) Screen; a Psychological Distress Scale; the Alcohol Use Disorder Identification Test (AUDIT); and self-report measures of tobacco use, perceived health status and adherence to anti-TB drugs and ART. Results: The majority of the participants (N = 3107) were new TB cases with a 55.9% HIV co-infection rate in this adult male and female sample 18 years and older. Significant predictors of non-adherence common to both anti-TB drugs and to dual therapy (ART and anti-TB drugs) included poverty, having one or more co-morbid health condition, being a high risk for alcohol mis-use and a partner who is HIV positive. An additional predictor for non-adherence to anti-TB drugs was tobacco use. Conclusions: A comprehensive treatment programme addressing poverty, alcohol mis-use, tobacco use and psycho-social counseling is indicated for TB patients (with and without HIV). The treatment care package needs to involve not only the health sector but other relevant government sectors, such as social development.IS

    Gender Inequalities in Education

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    The terrain of gender inequalities in education has seen much change in recent decades. This chapter reviews the empirical research and theoretical perspectives on gender inequalities in educational performance and attainment from early childhood to young adulthood. Much of the literature on children and adolescents attends to performance differences between girls and boys. Of course achievement in elementary and secondary school is linked to the level of education one ultimately attains including high school completion, enrollment in post secondary education, college completion and graduate and professional school experiences. We recommend three directions for future research: (a) interdisciplinary efforts to understand gender differences in cognitive development and non-cognitive abilities in early childhood, (b) research on the structure and practices of schooling, and (c) analyses of the intersectionality of gender with race, ethnicity, class, and immigrant statuses in creating complex patterns of inequalities in educational experiences and outcomes

    Does true Gleason pattern 3 merit its cancer descriptor?

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    Nearly five decades following its conception, the Gleason grading system remains a cornerstone in the prognostication and management of patients with prostate cancer. In the past few years, a debate has been growing whether Gleason score 3 + 3 = 6 prostate cancer is a clinically significant disease. Clinical, molecular and genetic research is addressing the question whether well characterized Gleason score 3 + 3 = 6 disease has the ability to affect the morbidity and quality of life of an individual in whom it is diagnosed. The consequences of treatment of Gleason score 3 + 3 = 6 disease are considerable; few men get through their treatments without sustaining some harm. Further modification of the classification of prostate cancer and dropping the label cancer for Gleason score 3 + 3 = 6 disease might be warranted

    Qualitative meta-synthesis of user experience of computerised therapy for depression and anxiety

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    Objective: Computerised therapies play an integral role in efforts to improve access to psychological treatment for patients with depression and anxiety. However, despite recognised problems with uptake, there has been a lack of investigation into the barriers and facilitators of engagement. We aimed to systematically review and synthesise findings from qualitative studies of computerised therapies, in order to identify factors impacting on engagement. Method: Systematic review and meta-synthesis of qualitative studies of user experiences of computer delivered therapy for depression and/or anxiety. Results: 8 studies were included in the review. All except one were of desktop based cognitive behavioural treatments. Black and minority ethnic and older participants were underrepresented, and only one study addressed users with a comorbid physical health problem. Through synthesis, we identified two key overarching concepts, regarding the need for treatments to be sensitive to the individual, and the dialectal nature of user experience, with different degrees of support and anonymity experienced as both positive and negative. We propose that these factors can be conceptually understood as the ‘non-specific’ or ‘common’ factors of computerised therapy, analogous to but distinct from the common factors of traditional face-to-face therapies. Conclusion: Experience of computerised therapy could be improved through personalisation and sensitisation of content to individual users, recognising the need for users to experience a sense of ‘self’ in the treatment which is currently absent. Exploiting the common factors of computerised therapy, through enhancing perceived connection and collaboration, could offer a way of reconciling tensions due to the dialectal nature of user experience. Future research should explore whether the findings are generalisable to other patient groups, to other delivery formats (such as mobile technology) and other treatment modalities beyond cognitive behaviour therapy. The proposed model could aid the development of enhancements to current packages to improve uptake and support engagement

    Dendritic cell-specific delivery of Flt3L by coronavirus vectors secures induction of therapeutic antitumor immunity

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    Efficacy of antitumor vaccination depends to a large extent on antigen targeting to dendritic cells (DCs). Here, we assessed antitumor immunity induced by attenuated coronavirus vectors which exclusively target DCs in vivo and express either lymphocyte- or DC-activating cytokines in combination with a GFP-tagged model antigen. Tracking of in vivo transduced DCs revealed that vectors encoding for Fms-like tyrosine kinase 3 ligand (Flt3L) exhibited a higher capacity to induce DC maturation compared to vectors delivering IL-2 or IL-15. Moreover, Flt3L vectors more efficiently induced tumor-specific CD8(+) T cells, expanded the epitope repertoire, and provided both prophylactic and therapeutic tumor immunity. In contrast, IL-2- or IL-15-encoding vectors showed a substantially lower efficacy in CD8(+) T cell priming and failed to protect the host once tumors had been established. Thus, specific in vivo targeting of DCs with coronavirus vectors in conjunction with appropriate conditioning of the microenvironment through Flt3L represents an efficient strategy for the generation of therapeutic antitumor immunity

    The ongoing pursuit of neuroprotective therapies in Parkinson disease

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    Many agents developed for neuroprotective treatment of Parkinson disease (PD) have shown great promise in the laboratory, but none have translated to positive results in patients with PD. Potential neuroprotective drugs, such as ubiquinone, creatine and PYM50028, have failed to show any clinical benefits in recent high-profile clinical trials. This 'failure to translate' is likely to be related primarily to our incomplete understanding of the pathogenic mechanisms underlying PD, and excessive reliance on data from toxin-based animal models to judge which agents should be selected for clinical trials. Restricted resources inevitably mean that difficult compromises must be made in terms of trial design, and reliable estimation of efficacy is further hampered by the absence of validated biomarkers of disease progression. Drug development in PD dementia has been mostly unsuccessful; however, emerging biochemical, genetic and pathological evidence suggests a link between tau and amyloid-β deposition and cognitive decline in PD, potentially opening up new possibilities for therapeutic intervention. This Review discusses the most important 'druggable' disease mechanisms in PD, as well as the most-promising drugs that are being evaluated for their potential efficiency in treatment of motor and cognitive impairments in PD

    Parent recommendations to support physical activity for families with young children: Results of interviews in deprived and affluent communities in South Wales (United Kingdom)

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    Background: Physical inactivity is the fourth leading cause of mortality worldwide. Early childhood is a critical period when healthy behaviours can be instilled for a future active lifestyle. We explored community, societal and environmental factors affecting child and family physical activity and sought parent recommendations to support physical activity in families with young children. Methods: We interviewed 61 parents expecting a child or with a baby ≤12 months (35 mother and father paired interviews and 26 interviews with mothers only). We purposively sampled families for neighbourhood deprivation status (Townsend Index; 26 affluent; 35 deprived). We conducted thematic analysis of interview transcripts using Bronfenbrenner's socio-ecological framework to guide interpretation. Results: We identified four themes: work family-life balance; spaces for activity; beliefs and attitudes; and physical activity facilitators. We found that parents from deprived neighbourhoods were more likely to be underactive because of a complex web of community, social and personal factors which reduced motivation and hindered opportunity for physical activity. To increase knowledge and opportunity, respondents suggested ‘help not tell’ messages covering ‘why’, ‘how’ and ‘where’ information about physical activity, and using physical activity to support community engagement and social interaction. Conclusions: Recommendations from parents highlight effective communication about the importance of early child and family physical activity and improved community access to safe facilities and opportunities. Both parents need to be engaged in designing interventions to support greater physical activity and healthy behaviours which are relevant and achievable in individuals’ lives

    Factors that potentially influence successful weight loss for adults with intellectual disabilities: a qualitative comparison

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    Background: People with intellectual disabilities are more at risk of obesity than the general population. Emerging literature indicates that multicomponent interventions are most effective, however, individual results are variable and little research exists as to why this is the case. Methods: Focus groups were conducted to explore lived experiences between two groups of adults with intellectual disabilities; an overweight group (n= 6) and a group identified as successful in losing weight (n= 6). Similarities and differences were explored across four domains. Transcripts were produced and analysed using Theoretical Thematic Analysis. Results: Similarities included service centre supports, basic food knowledge and issues restricting independence. The successful weight loss group had also internalised health messages, engaged with external reinforcement programmes, responded to positive feedback and demonstrated healthier dietary habits. Conclusion: Weight management interventions would benefit from understanding the influence that internalisation of health messages, effective reinforcement systems and positive feedback can have on supporting the adoption of healthier habits.The author(s) disclosed receipt of the following financial support for the research, authorship and/or publication of this article: This research was supported by funding from the charity RESPECT and the People Programme (Marie Curie Actions) of the European Union’s Seventh Framework Programme (FP7/2007-2013) under REA grant agreement no. PCOFUND-GA-2013-608728. Additional funding for PhD research was provided by Department of Education and Learning (DEL).peer-reviewe
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