Association of prevalence of active transport to work and incidence of myocardial infarction: A nationwide ecological study.

BACKGROUND: There is a paucity of population-based geospatial data about the association between active transport and myocardial infarction. We investigated the association between active transport to work and incidence of myocardial infarction. DESIGN: This ecological study of 325 local authorities in England included 43,077,039 employed individuals aged 25-74 years (UK Census, 2011), and 117,521 individuals with myocardial infarction (Myocardial Ischaemia National Audit Project, 2011-2013). METHODS: Bayesian negative binomial regression models were used to investigate the association of active transport to work and incidence of myocardial infarction adjusting for local levels of deprivation, obesity, smoking, diabetes and physical activity. RESULTS: In 2011, the prevalence of active transportation to work for people in employment in England aged 25-74 years was 11.4% (4,531,182 active transporters; 8.6% walking and 2.8% cycling). Active transport in 2011 was associated with a reduced incidence of myocardial infarction in 2012 amongst men cycling to work (incidence rate ratio (95% credible interval) 0.983 (0.967-0.999); and women walking to work (0.983 (0.967-0.999)) after full adjustments. However, the prevalence of active transport for men and women was not significantly associated with the combined incidence of myocardial infarction between 2011-2013 after adjusting for physical activity, smoking and diabetes. CONCLUSIONS: In England, the prevalence of active transportation was associated with a reduced incidence of myocardial infarction for women walking and men cycling to work in corresponding local geographic areas. The overall association of active transport with myocardial infarction was, however, explained by local area levels of smoking, diabetes and physical activity.

Dual-grating confocal-rainbow volume holographic imaging system designs for high depth resolution.

Confocal microscopy rejects out-of-focus light from the object by scanning a pinhole through the image and reconstructing the image point by point. Volume holographic imaging systems with bright-field illumination have been proposed as an alternative to conventional confocal-type microscopes that does not require scanning of a pinhole or a slit. However, due to wavelength-position degeneracy of the hologram, the high Bragg selectivity of the volume hologram is not utilized and system performance is not optimized. Confocal-rainbow illumination has been proposed as a means to remove the degeneracy and improve optical sectioning in these systems. In prior work, two versions of this system were illustrated: the first version had a separate illumination and imaging grating and the second used a single grating to disperse the incident light and to separate wavelengths in the imaging path. The initial illustration of the dual-grating system has limited depth resolution due to the low selectivity of the illumination grating. The initial illustration of the single-grating system has high depth resolution but does not allow optimization of the illumination path and requires high optical quality of the holographic filters. In this paper we consider the design and tolerance requirements of the dual-grating system for high depth resolution and demonstrate the results with an experimental system. An experimental system with two 1.8 mm thick planar holograms achieved a depth resolution of 7 µm with a field of view of 1.9 mm and a hologram dispersion matching tolerance of ±0.008°.