3,885 research outputs found

    On galaxy rotation curves from a continuum mechanics approach to modified gravity

    Get PDF
    We consider a modification of General Relativity motivated by the treatment of anisotropies in Continuum Mechanics. The Newtonian limit of the theory is formulated and applied to galactic rotation curves. By assuming that the additional structure of spacetime behaves like a Newtonian gravitational potential for small deviations from isotropy, we are able to recover the Navarro-Frenk-White profile of dark matter halos by a suitable identification of constants. We consider the Burkert profile in the context of our model and also discuss rotation curves more generally.Comment: 8 pages; v2 11 pages, heavily revised version, new title; v3 13 pages final versio

    Systematic versus opportunistic risk assessment for the primary prevention of cardiovascular disease

    Get PDF
    Background Screening programmes can potentially identify people at high cardiovascular risk and reduce cardiovascular disease (CVD) morbidity and mortality. However, there is currently not enough evidence showing clear clinical or economic benefits of systematic screening-like programmes over the widely practised opportunistic risk assessment of CVD in primary care settings. Objectives The primary objective of this review was to assess the effectiveness, costs and adverse effects of systematic risk assessment compared to opportunistic risk assessment for the primary prevention of CVD. Search methods We searched the Cochrane Central Register of Controlled Trials (CENTRAL) on the Cochrane Library, MEDLINE, EMBASE on 30 January 2015, and Web of Science Core Collection and additional databases on the Cochrane Library on 4 December 2014. We also searched two clinical trial registers and checked reference lists of relevant articles. We applied no language restrictions. Selection criteria We selected randomised controlled trials (RCTs) that assessed the effects of systematic risk assessment, defined as a screening-like programme involving a predetermined selection process of people, compared with opportunistic risk assessment which ranged from no risk assessment at all to incentivised case finding of CVD and related risk factors. Participants included healthy adults from the general population, including those who are at risk of CVD. Data collection and analysis Two review authors independently selected studies. One review author extracted data and assessed them for risk of bias and a second checked them. We assessed evidence quality using the GRADE approach and present this in a ’Summary of findings’ table. Main results Nine completed RCTs met the inclusion criteria, of which four were cluster-randomised. We also identified five ongoing trials. The included studies had a high or unclear risk of bias, and the GRADE ratings of overall quality were low or very low. The length of follow-up varied from one year in four studies, three years in one study, five or six years in two studies, and ten years in two studies. Eight studies recruited participants from the general population, although there were differences in the age ranges targeted. One study recruited family members of cardiac patients (high risk assessment). There were considerable differences between the studies in the interventions received by the intervention and control groups. There was insufficient evidence to stratify by the types of risk assessment approaches. Limited data were available on all-cause mortality (risk ratio (RR) 0.97, 95% confidence interval (CI) 0.92 to 1.02; 3 studies,103,571 participants, I² = 0%; low-quality evidence) and cardiovascular mortality (RR 1.00, 95% CI 0.90 to 1.11; 2 studies, 43,955 participants, I² = 0%), and suggest that screening has no effect on these outcomes. Data were also limited for combined non-fatal endpoints; overall, evidence indicates no difference in total coronary heart disease (RR 1.01, 95% CI 0.95 to 1.07; 4 studies, 5 comparisons, 110,168 participants, I² = 0%; low-quality evidence), non-fatal coronary heart disease (RR 0.98, 95% CI 0.89 to 1.09; 2 studies, 43,955 participants, I² = 39%), total stroke (RR 0.99, 95% CI 0.90 to 1.10; 2 studies, 79,631 participants, I² = 0%, low-quality evidence), and non-fatal stroke (RR 1.17, 95% CI 0.94 to 1.47; 1 study, 20,015 participants). Overall, systematic risk assessment appears to result in lower total cholesterol levels (mean difference (MD) -0.11 mmol/l, 95% CI -0.17 to -0.04, 6 studies, 7 comparisons, 12,591 participants, I² = 57%; very low-quality evidence), lower systolic blood pressure (MD -3.05 mmHg, 95% CI -4.84 to -1.25, 6 studies, 7 comparisons, 12,591 participants, I² = 82%; very low-quality evidence) and lower diastolic blood pressure (MD -1.34 mmHg, 95% CI -1.76 to -0.93, 6 studies, 7 comparisons, 12,591 participants, I² = 0%; low-quality evidence). One study assessed adverse effects and found no difference in psychological distress at five years (1126 participants). Authors' conclusions The results are limited by the heterogeneity between trials in terms of participants recruited, interventions and duration of follow-up. Limited data suggest that systematic risk assessment for CVD has no statistically significant effects on clinical endpoints. There is limited evidence to suggest that CVD systematic risk assessment may have some favourable effects on cardiovascular risk factors. The completion of the five ongoing trials will add to the evidence base

    Talk About Self Harm (TASH): participatory action research with young people, GPs and practice nurses to explore how the experiences of young people who self-harm could be improved in GP surgeries

    Get PDF
    Background: The incidence of self-harm in young people in primary care is increasing dramatically and many young people who self-harm visit their GP surgery as a first point of contact for help. Aim: To explore with young people, GPs and Practice Nurses; 1) why young people present with self-harm to primary care and 2) whether young people, GPs and Practice Nurses can take steps to have more helpful consultations about self-harm in GP surgeries that include self-help materials developed by young people being used to support such consultations to take place. Design and setting: Participatory action research with GPs, Practice Nurses and young people employed mixed methods to collect statistical and narrative data.Methods: Statistics from 285 young people’s medical records were captured including more detailed analyses of a random sample of 75 of these records. A series of 24 focus groups with a total of 45 GPs, Practice Nurses and Young People, with an average number of 8 participants in each group were conducted. Statistical data was subject to descriptive and inferential analyses and thematic analysis was applied to the transcripts from the focus groups. Results and conclusion: The type of self-harm young people presented with influenced whether they would see a GP or Practice Nurse. While self-help materials were welcomed and deemed helpful, young people, GPs and Practice Nurses were ambivalent about using these in short consultations where time was an overriding constraint. More research is needed on the feasibility of adopting self-help assisted interventions in GP surgeries
    corecore