Evaluation of fast atmospheric dispersion models in a regular street network

The need to balance computational speed and simulation accuracy is a key challenge in designing atmospheric dispersion models that can be used in scenarios where near real-time hazard predictions are needed. This challenge is aggravated in cities, where models need to have some degree of building-awareness, alongside the ability to capture effects of dominant urban flow processes. We use a combination of high-resolution large-eddy simulation (LES) and wind-tunnel data of flow and dispersion in an idealised, equal-height urban canopy to highlight important dispersion processes and evaluate how these are reproduced by representatives of the most prevalent modelling approaches: (i) a Gaussian plume model, (ii) a Lagrangian stochastic model and (iii) street-network dispersion models. Concentration data from the LES, validated against the wind-tunnel data, were averaged over the volumes of streets in order to provide a high-fidelity reference suitable for evaluating the different models on the same footing. For the particular combination of forcing wind direction and source location studied here, the strongest deviations from the LES reference were associated with mean over-predictions of concentrations by approximately a factor of 2 and with a relative scatter larger than a factor of 4 of the mean, corresponding to cases where the mean plume centreline also deviated significantly from the LES. This was linked to low accuracy of the underlying flow models/parameters that resulted in a misrepresentation of pollutant channelling along streets and of the uneven plume branching observed in intersections. The agreement of model predictions with the LES (which explicitly resolves the turbulent flow and dispersion processes) greatly improved by increasing the accuracy of building-induced modifications of the driving flow field. When provided with a limited set of representative velocity parameters, the comparatively simple street-network models performed equally well or better compared to the Lagrangian model run on full 3D wind fields. The study showed that street-network models capture the dominant building-induced dispersion processes in the canopy layer through parametrisations of horizontal advection and vertical exchange processes at scales of practical interest. At the same time, computational costs and computing times associated with the network approach are ideally suited for emergency-response applications

Modelling of the effect of ELMs on fuel retention at the bulk W divertor of JET

Effect of ELMs on fuel retention at the bulk W target of JET ITER-Like Wall was studied with multi-scale calculations. Plasma input parameters were taken from ELMy H-mode plasma experiment. The energetic intra-ELM fuel particles get implanted and create near-surface defects up to depths of few tens of nm, which act as the main fuel trapping sites during ELMs. Clustering of implantation-induced vacancies were found to take place. The incoming flux of inter-ELM plasma particles increases the different filling levels of trapped fuel in defects. The temperature increase of the W target during the pulse increases the fuel detrapping rate. The inter-ELM fuel particle flux refills the partially emptied trapping sites and fills new sites. This leads to a competing effect on the retention and release rates of the implanted particles. At high temperatures the main retention appeared in larger vacancy clusters due to increased clustering rate

The duality of ocean acidification as a resource and a stressor

Ecologically dominant species often define ecosystem states, but as human disturbances intensify, their subordinate counterparts increasingly displace them. We consider the duality of disturbance by examining how environmental drivers can simultaneously act as a stressor to dominant species and as a resource to subordinates. Using a model ecosystem, we demonstrate that CO2-driven interactions between species can account for such reversals in dominance; i.e., the displacement of dominants (kelp forests) by subordinates (turf algae). We established that CO2 enrichment had a direct positive effect on productivity of turfs, but a negligible effect on kelp. CO2 enrichment further suppressed the abundance and feeding rate of the primary grazer of turfs (sea urchins), but had an opposite effect on the minor grazer (gastropods). Thus, boosted production of subordinate producers, exacerbated by a net reduction in its consumption by primary grazers, accounts for community change (i.e., turf displacing kelp). Ecosystem collapse, therefore, is more likely when resource enrichment alters competitive dominance of producers, and consumers fail to compensate. By recognizing such duality in the responses of interacting species to disturbance, which may stabilize or exacerbate change, we can begin to understand how intensifying human disturbances determine whether or not ecosystems undergo phase shifts

Factors associated with engagement in HIV care for young people living with perinatally acquired HIV in England: An exploratory observational cohort study

Identifying which young people living with perinatally acquired HIV (PHIV) are less likely to engage in care is crucial to allow targeted interventions to support them to attend clinic. We adapted an existing Engagement in Care (EIC) algorithm for adults with HIV in England, for use in young people. We applied it to data from young people with PHIV in the Adolescents and Adults Living with Perinatal HIV (AALPHI) cohort. The algorithm predicts the timing of the next scheduled clinic visit, within 1–6 months of current visit, based on routine clinical data. Follow-up was 12-months from AALPHI baseline interview. Each person-month was classified as engaged in care or not. Logistic regression models (allowing for clustered data) were used to explore baseline characteristics associated with being engaged in care, adjusting for a priori variables (time from interview, sex, age, ethnicity, country of birth). Potential characteristics were across 7 domains: sociodemographic; risk behaviour practices; mental health; cognition; clinic setting; HIV management and experience; and HIV clinical markers. Of 316 young people, 187(59%) were female, 271(86%) of black ethnicity and 184(58%) born abroad. At baseline, median [IQR] age was 17[15–18] years, and 202(69%) had viral load ≤50 copies/ml(c/mL). 87% of 3,585 person-months were classified as engaged in care. Characteristics independently associated with poorer odds of being engaged in care were: Asian/mixed/other ethnicity, vs. black ethnicity (OR 0.44, 95% CI 0.25, 0.78, p = 0.02); ever self-harmed, vs. not (OR 0.55, 95% CI 0.32, 0.95, p = 0.03); on antiretroviral therapy (ART) and self-assessed bad/not so good adherence (OR 0.46, 95% CI 0.25, 0.84) or not on ART (OR 0.64, 95% CI 0.64, 1.21) vs. on ART and good/excellent adherence (p = 0.04)); baseline VL>50c/mL, vs VL≤50c/mL (OR 0.47, 95% CI 0.30, 0.75, p = 0.002). These characteristics can help identify individuals requiring enhanced support to maintain service engagement

Assessment of alcohol problems using AUDIT in a prison setting: more than an 'aye or no' question

<br>Background: Alcohol problems are a major UK and international public health issue. The prevalence of alcohol problems is markedly higher among prisoners than the general population. However, studies suggest alcohol problems among prisoners are under-detected, under-recorded and under-treated. Identifying offenders with alcohol problems is fundamental to providing high quality healthcare. This paper reports use of the AUDIT screening tool to assess alcohol problems among prisoners.</br> <br>Methods: Universal screening was undertaken over ten weeks with all entrants to one male Scottish prison using the AUDIT standardised screening tool and supplementary contextual questions. The questionnaire was administered by trained prison officers during routine admission procedures. Overall 259 anonymised completed questionnaires were analysed.</br> <br>Results: AUDIT scores showed a high prevalence of alcohol problems with 73% of prisoner scores indicating an alcohol use disorder (8+), including 36% having scores indicating ‘possible dependence’ (20-40). AUDIT scores indicating ‘possible dependence’ were most apparent among 18-24 and 40-64 year-olds (40% and 56% respectively). However, individual questions showed important differences, with younger drinkers less likely to demonstrate habitual and addictive behaviours than the older age group. Disparity between high levels of harmful/hazardous/dependent drinking and low levels of ‘treatment’ emerged (only 27% of prisoners with scores indicating ‘possible dependence’ reported being ‘in treatment’). Self-reported associations between drinking alcohol and the index crime were identified among two-fifths of respondents, rising to half of those reporting violent crimes.</br> <br>Conclusions: To our knowledge, this is the first study to identify differing behaviours and needs among prisoners with high AUDIT score ranges, through additional analysis of individual questions. The study has identified high prevalence of alcohol use, varied problem behaviours, and links across drinking, crime and recidivism, supporting the argument for more extensive provision of alcohol-focused interventions in prisons. These should be carefully targeted based on initial screening and assessment, responsive, and include care pathways linking prisoners to community services. Finally, findings confirm the value and feasibility of routine use of the AUDIT screening tool in prison settings, to considerably enhance practice in the detection and understanding of alcohol problems, improving on current more limited questioning (e.g. ‘yes or no’ questions).</br&gt

Women, resettlement and desistance

With the numbers of women imprisoned increasing across Western jurisdictions over the last 15 or so years, so too have the numbers of women returning to the community following a period in custody. Despite increasing policy attention in the UK and elsewhere to prisoner resettlement, women’s experiences on release from prison have received limited empirical and policy attention. Drawing upon interviews with women leaving prison in Victoria, Australia, this article discusses the resettlement challenges faced by the women and highlights their similarity to the experiences of women leaving prison in other jurisdictions. Women had mixed (and predominantly negative) experiences and views of accessing services and supports following release, though experiences of parole supervision by community corrections officers were often positive, especially if women felt valued and supported by workers who demonstrated genuine concern. Analysis of factors associated with further offending and with desistance, points to the critical role of flexible, tailored and women-centred post-release support building, and, where possible, upon relationships established with women while they are still in prison

Brief report:effects of sensory sensitivity and intolerance of uncertainty on anxiety in mothers of children with autism spectrum disorder

This study examined the relations between anxiety and individual characteristics of sensory sensitivity (SS) and intolerance of uncertainty (IU) in mothers of children with ASD. The mothers of 50 children completed the Hospital Anxiety and Depression Scale, the Highly Sensitive Person Scale and the IU Scale. Anxiety was associated with both SS and IU and IU was also associated with SS. Mediation analyses showed direct effects between anxiety and both IU and SS but a significant indirect effect was found only in the model in which IU mediated between SS. This is the first study to characterize the nature of the IU and SS interrelation in predicting levels of anxiety