Investment lags: A numerical approach

In this paper we use a mixture of numerical methods including finite difference and body fitted co-ordinates to form a robust stable numerical scheme to solve the investment lag model presented in the paper by Bar-Ilan and Strange (1996). This allows us to apply our methodology to models with different stochastic processes that does not have analytic solutions. Copyright © 2014 SCITEPRESS

Optimal staffing policy: A service system with stochastic travel times

Private sector operators of response services such as ambulance, fire or police etc. are often regulated by targets on the distribution of response times. This may result in inefficient overstaffing to ensure those targets are met. In this paper, we use a network chain of M/M/K queues to model the arrival and completion of jobs on the system so that quantities such as the expected total time waiting for all jobs can be calculated. The Markov nature enables us to evoke the Hamilton Jacobi Bellman equation (HJB) principle to optimize the required number of staff whilst still meeting targets

A systematic review of baseline psychosocial characterisation in dietary randomised controlled trials for weight loss

Background/objective: To investigate the extent of baseline psychosocial characterisation of subjects in published dietary randomised controlled trials (RCTs) for weight loss. Subjects/methods: Systematic review of adequately sized (n⩾10) RCTs comprising ⩾1 diet-alone arm for weight loss were included for this systematic review. More specifically, trials included overweight (body mass index >25 kg/m2) adults, were of duration ⩾8 weeks and had body weight as the primary outcome. Exclusion criteria included specific psychological intervention (for example, Cognitive Behaviour Therapy (CBT)), use of web-based tools, use of supplements, liquid diets, replacement meals and very-low calorie diets. Physical activity intervention was restricted to general exercise only (not supervised or prescribed, for example, VO2 maximum level). Results: Of 176 weight-loss RCTs published during 2008–2010, 15 met selection criteria and were assessed for reported psychological characterisation of subjects. All studies reported standard characterisation of clinical and biochemical characteristics of subjects. Eleven studies reported no psychological attributes of subjects (three of these did exclude those taking psychoactive medication). Three studies collected data on particular aspects of psychology related to specific research objectives (figure scale rating, satiety and quality-of-life). Only one study provided a comprehensive background on psychological attributes of subjects. Conclusion: Better characterisation in behaviour-change interventions will reduce potential confounding and enhance generalisability of such studies