A Recipe for State Dependent Distributed Delay Differential Equations

We use the McKendrick equation with variable ageing rate and randomly distributed maturation time to derive a state dependent distributed delay differential equation. We show that the resulting delay differential equation preserves non-negativity of initial conditions and we characterise local stability of equilibria. By specifying the distribution of maturation age, we recover state dependent discrete, uniform and gamma distributed delay differential equations. We show how to reduce the uniform case to a system of state dependent discrete delay equations and the gamma distributed case to a system of ordinary differential equations. To illustrate the benefits of these reductions, we convert previously published transit compartment models into equivalent distributed delay differential equations.Comment: 28 page

Performance indicators and health promition targets

This paper discusses the usefulness of performance indicators in health promotion. Health promotion and target-setting in health have both risen to the fore in the light of the Health of the Nation White Paper. This coupled with increasing pressure on all sectors of health care to demonstrate their “value-for-money” have meant that health promotion activities are being scrutinised as never before. Performance indicators have been one suggested means of ensuring movement towards Health of the Nation targets and value-for-money in health promotion. The paper outlines the uses to which performance indicators have been put elsewhere in the NHS and argues that they are unlikely to be directly transferrable to health promotion. Criteria for successful performance indicators in health promotion are outlined. However, it is doubtful whether these criteria will be fulfilled to any useful extent at present. The theory of health promotion is characterised by many different views of what is an appropriate outcome measure of any health promotion intervention and therefore what will be an appropriate performance indicator. Consensus in theory is needed before any consensus on what is most suitable to measure is reached. In addition, any outcomes from health promotion, by its very nature, are likely to become apparent only over long periods of time, if at all. This reduces the likelihood of attribution and the feasibility of assigning responsibility for meeting targets. Nonetheless, there is some scope for performance indicators in health promotion and their use as an internal management tool and as mechanisms for reaching external micro and macro level health-related targets is discussed. A collection of suggested macro performance indicators from the Health Education Authority are evaluated according to the criteria developed earlier. It is argued that at present these do not qualify as performance indicators, although they are certainly useful as monitoring tools. The paper concludes with priorities for further research in this area. Despite the emphasis on target-setting brought about by the Health of the Nation, knowledge and expertise in performance indicators for health promotion is lacking. This is a matter of urgent concern. There are many complex conceptual and practical problems which will influence the future role and choice of performance indicators in health promotion. These range from the fundamental, differing views about the definition of health education and health promotion, to the practical, a lack of knowledge at the community level about how to start looking for indicators, and the technical, a lack of clear responsibility for meeting macro-level targets.performance indicators, targets

Into the realm of social capital for adolescents: a latent profile analysis

Background Recent reports of increasing prevalence of frequent health complaints and mental health problems among adolescents call for directing more attention on determinants of adolescent health. The relationship between health and social capital has gained increased attention since the early 2000’s and research at review level confirms the importance of social capital for health outcomes, despite methodological heterogeneity. The aim of this study was to identify distinct profiles of family, school and peer social capital in a nationally representative sample of adolescents and to explore health outcomes in those profiles. Method Cross-sectional data from the Swedish Health Behaviour of School-aged Children 2013/14 was used for this study. The analytical sample consisted of 7,804 adolescents aged 11-, 13- and 15-years. Items representing sense of belonging and emotional support were assessed in three contexts; family, school and among peers. Latent profile analyses (LPA) were run to determine social capital profiles. Health outcomes included frequent health complaints and life satisfaction, while socioeconomic status and genders were included as predictors. Results The results show that five distinct profiles best represent the data for 11- and 15-year olds, while a four-profile model was optimal for 13-year olds. Some profiles were recurrent between age groups but unique profiles were also found. Health outcomes were significantly different between profiles depending on levels of social capital in the different contexts. Conclusions This study provides novel insight into how social capital co-occurs among adolescents within the contexts of family, school and peers and how this translates into differences in health outcomes. The national representativeness of the sample increases the implications of the results and contributes to meaningful insights that help explain the interactions of social capital in multiple contexts, complementing what is previously known about the relationship with adolescent health. © 2019 Ahlborg et al. This is an open access article distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited

A major role for protein kinase C in calcium-activated exocytosis in permeabilised adrenal chromaffin cells

AbstractThe role of endogenously activated protein kinase C in calcium-activated exocytosis was examined in digitonin-permeabilised bovine adrenal chromaffin cells. Protein kinase C activity was reduced by down-regulation following long-term treatment with PMA or by using the inhibitor sphingosine. Both treatments resulted in a substantial reduction in catecholamine secretion elicited by micromolar calcium, indicating that endogenous activation of protein kinase C is a major requirement for calcium-activated exocytosis in chromaffin cells

Well-being profiles in adolescence:psychometric properties and latent profile analysis of the mental health continuum model – a methodological study

Abstract Background: The Adolescent Mental Health Continuum Short Form (MHC-SF) is a psychometrically valid tool to evaluate the domains of subjective well-being, but there is a lack of investigations which could distinguish subgroups with distinct subjective well-being profiles based on this measurement. Therefore, after testing the competing measurement models of the MHC-SF, our main aim was to identify subjective well-being profiles in a large adolescent sample. Methods: On a representative Hungarian adolescent sample (N=1572; 51% girl; mean age was 15.39, SD=2.26) confirmatory factor analyses (CFA) and exploratory structural equation modeling (ESEM) were used to test the factor stucture of the Adolescents MHC-SF. In addition, gender invariance of the best fitting model was also tested. Latent Profile Analyses (LPA) were conducted to reveal distinct subgroups and these profiles were then compared. Results: Results support the bifactor model of MHC-SF: the general and specific well-being factors which were invariant across gender. LPA yielded four subgroups, three of them have been theoretically hypothesized in previous works (i.e. flourishing, moderate mental health, languishing), but an emotionally vulnerable subgroup also emerged. Compared to the languishing group, this new subgroup demonstrated higher scores on prosocial behaviour, but had comparable level of loneliness and internalizing symptoms. Conclusions: Our results suggest that the MHC-SF is a reliable and valid instrument for assessing overall well-being and its components. In addition, the identification of young people to be at risk for low mental health may help us to tailor mental health promotion programs to their special needs. Keywords: Well-being, Positive Mental Health, Mental Health Continuum Model, Adolescents, Confirmatory Factor Analysis, Exploratory Structural Equation Modeling, Gender Invariance, Latent Profile Analyse