Thermal light cannot be represented as a statistical mixture of single pulses

We ask whether or not thermal light can be represented as a mixture of single broadband coherent pulses. We find that it cannot. Such a mixture is simply not rich enough to mimic thermal light; indeed, it cannot even reproduce the first-order correlation function. We show that it is possible to construct a modified mixture of single coherent pulses that does yield the correct first-order correlation function at equal space points. However, as we then demonstrate, such a mixture cannot reproduce the second-order correlation function.Comment: 5 pages, 2 figures. Published versio

Association of Social Support and Cognitive Aging Modified by Sex and Relationship Type: A Prospective Investigation in the English Longitudinal Study of Ageing

We examined whether between-person differences (PM) and within-person change in levels of social support were associated with age-related cognitive decline, and whether these associations varied by sex and by relationship type. Executive function and memory scores over eight years (2002-2010) were analysed by mixture models (10,241 adults’ aged≥50 years) in the English Longitudinal Study of Ageing. PM and within-person change in positive social support and negative social support were independently associated with cognitive decline in different ways by sex and relationship type. Among men, higher-than-others positive social support from spouse/partner was associated with slower cognitive decline (executive function: βPM*time-in-study = 0.005, 95%CI: 0.001, 0.010; memory: βPM*time-in-study = 0.006, 95%CI 0.000, 0.012); whereas high negative social support from all relationship types was associated with accelerated decline in executive function (all-relationships-combined: βPM* time-in-study = -0.005, 95%CI: -0.008, -0.002). For women, higher-than-others positive social support from children (β=0.037, 95%CI: 0.010, 0.064) and friends (β=0.115, 95%CI: 0.081, 0.150) but not from spouse/partner (β=-0.034, 95%CI: -0.059, -0.009) or extended family (β=-0.035, 95%CI: -0.064, -0.006) was associated with higher executive function. Associations between social support and age-related cognitive decline vary across different relationship types for men and women

Developing a questionnaire to assess community severance, walkability, and wellbeing: results from the Street Mobility Project in London

This working paper describes the development of the survey questionnaire component of the toolkit designed to measure community severance, and assess its potential associations with transport and health. We discuss the cognitive testing and piloting of the questionnaire in two contrasting case study areas in inner London, and present results from the survey data

Income-based inequalities in hypertension and in undiagnosed hypertension: analysis of Health Survey for England data

Objective: To quantify income-based inequalities in hypertension and in undiagnosed hypertension. Methods: We used nationally representative data from 28 002 adults (aged 16 years and older) living in private households who participated in the cross-sectional Health Survey for England 2011–2016. Using bivariate probit regression modelling, we jointly modelled hypertension and self-reported previous diagnosis of hypertension by a doctor or nurse. We then used the model estimates to quantify inequalities in undiagnosed hypertension. Inequalities, using household income tertiles as an indicator of socioeconomic status, were quantified using average marginal effects (AMEs) after adjustment for confounding variables. Results: Overall, 32% of men and 27% of women had survey-defined hypertension (measured blood pressure ≥140/90 mmHg and/or currently using medicine to treat high blood pressure). Higher proportions (38% of men and 32% of women) either self-reported previous diagnosis or had survey-defined hypertension. Of these, 65% of men and 70% of women had diagnosed hypertension. Among all adults, participants in low-income versus high-income households had a higher probability of being hypertensive [AMEs: men 2.1%; 95% confidence interval (CI): −0.2, 4.4%; women 3.7%; 95% CI: 1.8, 5.5%] and of being diagnosed as hypertensive (AMEs: men 2.0%; 95% CI: 0.4, 3.7%; women 2.5%; 95% CI: 1.1, 3.9%). Among those classed as hypertensive, men in low-income households had a marginally lower probability of being undiagnosed than men in high-income households (AME: −5.2%; 95% CI: −10.5, 0.1%), whereas no difference was found among women. Conclusion: Our findings suggest that income-based inequalities in hypertension coexist with equity in undiagnosed hypertension

Agriculture and climate change mitigation in the developing world

Agricultural activities in the developing world directly contribute about 4.23 GtCO2eq/y to the current anthropogenic forcing of the global climate, and indirectly a further approximately 3.93GtCO2eq/y through forest clearing and degradation. Together they constitute a quarter of the total global climate forcing from all sources. Many proven agricultural practices and policies can reduce this impact on the global climate without compromising food production, or reduce the climate impact per unit of agricultural production. A reasonable target by 2030 for climate mitigation in developing world agriculture, taking into account the large difference between technical potentials and economically viable adoption rates and noting the equity issues relating to the mitigation activities in the developing world, is around 1.2 GtCO2eq/y for agriculture (~ 22% of projected unmitigated agricultural emissions by 2030) and 1.2 GtCO2eq/y for avoided and more climate-appropriate land use changes (~ 30% of current land use change related emissions)