Measurements of reflected overpressure in the extreme near field

Blast protection design requires a detailed knowledge of the loading imparted on a structure by a particular blast threat. This includes an understanding of the mechanisms involved in the rapid energy release that leads to fireball expansion and air shock development. In the far field (Z > 2 m/kg1/3) reliable semi-empirical methods exist for both the positive and negative phases of the blast wave. In the far field the explosion is sufficiently far away that only the propagating air shock interacts with the structure, while in the near field the fireball is still driving the air shock and can itself interact with the structure. There is currently a lack of reliable experimental data in this near field region, as the incredibly high pressures and temperatures pose particular experimental challenges. This is particularly the case in the extreme near field (Z < 0.5 m/kg1/3), where semi-empirical and physics-based predictions can vary by an order of magnitude. This paper presents the design of an experimental facility capable of recording spatially resolved reflected pressures in the extreme near field. The Mechanisms and Characterisation of Explosions (MaCE) facility is an evolution of the Characterisation of Blast Loading (CoBL) facility used for buried blasts, but with key near fieldspecific adaptations. An array of Hopkinson pressure bars embedded in a stiff target plate is used to make pressure measurements over a 100 mm radius instrumented area. Maraging steel pressure bars and specially designed strain gauges are used to increase the measurement capacity from 600 MPa to 1800 MPa, and 33 pressure bars in a radial grid are used to improve the spatial resolution from 25 mm to 12.5 mm. In addition, the pressure bar diameter is reduced from 10 mm to 4 mm, which greatly reduces stress wave dispersion, increasing the effective bandwidth. This enables the observation of high-frequency features in the pressure measurements, which is vital for validating the near-field transient effects predicted by numerical modelling and developing effective blast mitigation methods

MicroBlast - a benchmarking study of gramme-scale explosive trials

Explosions are a pressing and pervading threat in the modern world. The extensive damage caused by recent large scale urban explosions such as Tianjin (2015) and Beirut (2020) has highlighted a key gap in our knowledge. That is, we still do not yet understand, nor can we reliably and rapidly predict, blast loading in complex cityscape environments. Accordingly, determination of consequences related to risk, structural damage, and casualty numbers, is severely limited. Current experimental approaches do not have the sophistication nor fidelity required to accurately measure blast loading in urban environments, and there is a significant and growing disparity in the complexity with which numerical models and experimental work can operate. Because of this, key insights gained from detailed modelling studies have not been validated, and we do not yet fully understand how blast waves propagate and interact with multiple obstacles. This paper presents the development of a series of experimental studies aimed at addressing this shortfall. The ultimate objective of this work is to develop the MicroBlast facility: an ultra small-scale testing apparatus for rapid, high-rate, high-resolution, multi-parameter measurements of blast loading in complex environments. Here, we present results from preliminary trials aimed at establishing the reliability and repeatability of small-scale explosive testing, in increasingly complex layouts. The results are directly compared to commensurate larger-scale test data to confirm scalability of gramme-scale detonations

Making sense of being at 'high risk' of coronary heart disease within primary prevention

types: Journal ArticleCurrent National Health Service policy advocates screening to identify individuals at 'high risk' of cardio-vascular disease (CHD) in primary care. This article utilizes the work of Radley to explore how 'high risk' of CHD patients make sense of their new risk status. Results are presented here from a nested qualitative study within a quantitative randomized trial of a CHD risk intervention in primary care. 'Discovery' interviews were conducted with 'high risk' participants (n = 38, mean age = 55) two weeks after intervention and thematically analysed. In response to perceived threat, many participants sought to both 'minimize' and 'normalize' their risk status. They also reported intentions to act, particularly concerning dietary change and exercise, although less so for smoking amongst the lower socio-economic status participants. Such perceptions and intentions were contextualized within the life-course of later middle-age, so that both being at risk, and being treated for risk, were normalized as part of growing older. Social position, such as gender and SES, was also implicated. CHD risk interventions should be context-sensitive to the life-course and social position of those who find themselves at 'high risk' of CHD in later middle-age

Cannabigerol is a novel, well-tolerated appetite stimulant in pre-satiated rats

Rationale The appetite-stimulating properties of cannabis are well documented and have been predominantly attributed to the hyperphagic activity of the psychoactive phytocannabinoid, ∆9-tetrahydrocannabinol (∆9-THC). However, we have previously shown that a cannabis extract devoid of ∆9-THC still stimulates appetite, indicating that other phytocannabinoids also elicit hyperphagia. One possible candidate is the non-psychoactive phytocannabinoid cannabigerol (CBG), which has affinity for several molecular targets with known involvement in the regulation of feeding behaviour. Objectives The objective of the study was to assess the effects of CBG on food intake and feeding pattern microstructure. Methods Male Lister hooded rats were administered CBG (30–120 mg/kg, per ora (p.o.)) or placebo and assessed in open field, static beam and grip strength tests to determine a neuromotor tolerability profile for this cannabinoid. Subsequently, CBG (at 30–240 mg/kg, p.o.) or placebo was administered to a further group of pre-satiated rats, and hourly intake and meal pattern data were recorded over 2 h. Results CBG produced no adverse effects on any parameter in the neuromotor tolerability test battery. In the feeding assay, 120–240 mg/kg CBG more than doubled total food intake and increased the number of meals consumed, and at 240 mg/kg reduced latency to feed. However, the sizes or durations of individual meals were not significantly increased. Conclusions Here, we demonstrate for the first time that CBG elicits hyperphagia, by reducing latency to feed and increasing meal frequency, without producing negative neuromotor side effects. Investigation of the therapeutic potential of CBG for conditions such as cachexia and other disorders of eating and body weight regulation is thus warranted

Recent development and research at the University of Sheffield blast lab in Buxton, UK

The Blast and Impact Dynamics Lab in Buxton, UK has recently undergone a significant refurbishment due to investment by the University of Sheffield and funding from the Engineering & Physical Sciences Research Council (EPSRC) through a Strategic Equipment Grant. This has complimented development in measurement techniques funded through standard EPSRC grants and commercial blast testing undertaken by Blastech Ltd. a spin out company of the University of Sheffield

Far-field positive phase blast parameter characterisation of RDX and PETN based explosives

A significant amount of scientific effort has been dedicated to measuring and understanding the effects of explosions, leading to the development of semi-empirical methods for rapid prediction of blast load parameters. The most well-known of these, termed the Kingery and Bulmash method, makes use of polylogarithmic curves derived from a compilation of medium to large scale experimental tests performed over many decades. However, there is still no general consensus on the accuracy and validity of this approach, despite some researchers reporting consistently high levels of agreement. Further, it is still not known whether blast loading can be considered deterministic, or whether it is intrinsically variable, the extent of this variability, and the range and scales over which these variations are observed. This article critically reviews historic and contemporary blast experiments, including newly generated arena tests with RDX and PETN-based explosives, with a view to demonstrating the accuracy with which blast load parameters can be predicted using semi-empirical approaches

Neuromotor tolerability and behavioural characterisation of cannabidiolic acid, a phytocannabinoid with therapeutic potential for anticipatory nausea

Rationale: Anticipatory nausea (AN) is a poorly controlled side-effect experienced by chemotherapy patients. Currently, pharmacotherapy is restricted to benzodiazepine anxiolytics, which have limited efficacy, significant sedative effects, and induce dependency. The non-psychoactive phytocannabinoid, cannabidiolic acid (CBDA), has shown considerable efficacy in pre-clinical AN models, however determination of its neuromotor tolerability profile is crucial to justify clinical investigation. Provisional evidence for appetite-stimulating properties also requires detailed investigation. Objectives: To assess the tolerability of CBDA in locomotor activity, motor coordination and muscular strength tests, and additionally for ability to modulate feeding behaviours. Methods: Male Lister hooded rats administered CBDA (0.05-5 mg/kg; p.o.) were assessed in habituated open field (for locomotor activity), static beam and grip strength tests. A further study investigated whether these CBDA doses modulated normal feeding behaviour. Finally, evidence of anxiolytic-like effects in the habituated open field prompted testing of 5 mg/kg CBDA for anxiolytic-like activity in unhabituated open field, light/dark box and novelty-supressed feeding (NSF) tests. Results: CBDA had no adverse effects upon performance in any neuromotor tolerability test, however anxiolytic-like behaviour was observed in the habituated open field. Normal feeding behaviours were unaffected by any dose. CBDA (5 mg/kg) abolished the increased feeding latency in the NSF test induced by the 5-HT1AR antagonist, WAY-100,635, indicative of anxiolytic-like effects, but had no effect on anxiety-like behaviour in the novel open field or light/dark box. Conclusions: CBDA is very well tolerated and devoid of the sedative side-effect profile of benzodiazepines, justifying its clinical investigation as a novel AN treatment

A Q-methodological study of 'smoking identities'

publication-status: Publishedtypes: ArticleIn contrast to the psychological literature on adolescent smoking, little research has investigated the social identities of adult smokers. This study aimed to identify shared ‘smoking identities’ amongst a sample of 64 British smokers from different socio-economic groups using Q-methodology. Participants were asked to sort 70 items concerning smoking and smokers according to their agreement/disagreement with them. The 64 Q-sorts were then subjected to a by-person factor analysis yielding six factors, with the first four interpretable factors being presented here. Each factor is understood to represent a distinct ‘identity position’. The first two, the ‘addicted’ smoker, and the ‘in control’ smoker, oriented around a biomedical model of smoking as an addictive health risk. The final two, the ‘no big deal’ smoker and the ‘proud’ smoker reflected alternative understandings and values. The identity positions also differed in the extent to which smoking was considered a core part of self-identity. Unpacking the ‘smoking identities’ of current smokers offers the opportunity to devise targeted health promotion.Economic and Social Research Counci