Staffing a Call Center with Uncertain Arrival Rate and Absenteeism

This paper proposes simple methods for staffing a single-class call center with uncertain arrival rate and uncertain staffing due to employee absenteeism. The arrival rate and the proportion of servers present are treated as random variables. The basic model is a multi-server queue with customer abandonment, allowing non-exponential service-time and time-to-abandon distributions. The goal is to maximize the expected net return, given throughput benefit and server, customer-abandonment and customer-waiting costs, but attention is also given to the standard deviation of the return. The approach is to approximate the performance and the net return, conditional on the random model-parameter vector, and then uncondition to get the desired results. Two recently-developed approximations are used for the conditional performance measures: first, a deterministic fluid approximation and, second, a numerical algorithm based on a purely Markovian birth-and-death model, having state-dependent death rates

Using Football Cultures as a Vehicle to Improve Mental Health in Men: The Case of the Redcar and Cleveland Boot Room

This paper sets out to appraise (from the perspective of members) the impact of a localized, football-based mental health intervention. Commissioned in late 2015, the ‘Redcar and Cleveland Boot Room (BR)’ was implemented in response to mass redundancy in the local area, coupled with regional suicide rates in men that exceed the national average. Interactive discussions with BR members revealed that: (a) the language of football and shared identity were important for initiating and sustaining engagement in the BR; (b) peer-support and mentoring combined with member-led activities were active ingredients of the BR and (c) that the BR was an effective vehicle for building mental health resilience. This evaluation adds to the evidence base on the value of football as a context to engage adult males in community-based interventions targeting mental health resilience

Ethical issues, research and vulnerability : gaining the views of children and young people in residential care

Children and young people in residential care are some of the most vulnerable in our society. They may have experienced violence and physical, sexual or emotional abuse. They may be involved in offending or the misuse of drugs and alcohol. They are separated from their families and have to cope with living in a group situation with other young people and staff members. Children and young people in residential care also possess strengths, competencies and resilience. We have much to learn from their experiences and perspectives, both generally and surrounding their time in care. This paper will address the ethical issues which arise from gaining the views of children and young people in residential care, drawing on the experience of carrying out three studies in particular (Kendrick et al. 2004, The development of a residential unit working with sexually aggressive young men. In: H.G. Eriksson and T. Tjelflaat, eds. Residential care: horizons for the new century. Aldershot: Ashgate, 38-55; Docherty et al. 2006, Designing with care: interior design and residential child care. Farm7 and SIRCC. http://www.sircc.strath.ac.uk/publications/Designing_with_Care.pdf; Steckley, L. and Kendrick, A., 2005. Physical restraint in residential child care: the experiences of young people and residential workers. Childhoods 2005: Children and Youth in Emerging and Transforming Societies, University of Oslo, Norway, 29 June-3 July 2005, Steckley and Kendrick 2007, Young people's experiences of physical restraint in residential care: subtlety and complexity in policy and practice. In: M. Nunno, L. Bullard and D. Day, eds. For our own safety: examining the safety of high-risk interventions for children and young people. Washington, DC: Child Welfare League of America, forthcoming). The paper will discuss: information, consent and choice about involvement in the research; confidentiality, privacy and safety. It will also explore some of the more complex issues of ethical good practice which arise from researching children in their own living space. The negotiation of children's time and space must be approached carefully, with consideration of their rights and wishes. Sensitivity to children and young people's priorities and preoccupations must be paramount

Working with challenging behaviour

This section offers some ways of thinking about behaviour, our immediate objective in managing that behaviour, and our primary task in working with young people; these ways of thinking can bring greater clarity and effectiveness. This section also addresses self and relationship as inextricable components of working with challenging behaviour. Physical restraint is briefly discussed as the extreme end of working with challenging behaviour, and finally, some practical advice and further reading are offered

Phospholipid Composition Modulates Carbon Nanodiamond-Induced Alterations in Phospholipid Domain Formation

This document is the Accepted Manuscript version of a Published Work that appeared in final form in Langmuir, copyright © American Chemical Society after peer review and technical editing by the publisher. To access the final edited and published work see http://doi.org/10.1021/la504923j.The focus of this work is to elucidate how phospholipid composition can modulate lipid nanoparticle interactions in phospholipid monolayer systems. We report on alterations in lipid domain formation induced by anionically engineered carbon nanodiamonds (ECNs) as a function of lipid headgroup charge and alkyl chain saturation. Using surface pressure vs area isotherms, monolayer compressibility, and fluorescence microscopy, we found that anionic ECNs induced domain shape alterations in zwitterionic phosphatidylcholine lipids, irrespective of the lipid alkyl chain saturation, even when the surface pressure vs area isotherms did not show any significant changes. Bean-shaped structures characteristic of dipalmitoylphosphatidylcholine (DPPC) were converted to multilobed, fractal, or spiral domains as a result of exposure to ECNs, indicating that ECNs lower the line tension between domains in the case of zwitterionic lipids. For membrane systems containing anionic phospholipids, ECN-induced changes in domain packing were related to the electrostatic interactions between the anionic ECNs and the anionic lipid headgroups, even when zwitterionic lipids are present in excess. By comparing the measured size distributions with our recently developed theory derived by minimizing the free energy associated with the domain energy and mixing entropy, we found that the change in line tension induced by anionic ECNs is dominated by the charge in the condensed lipid domains. Atomic force microscopy images of the transferred anionic films confirm that the location of the anionic ECNs in the lipid monolayers is also modulated by the charge on the condensed lipid domains. Because biological membranes such as lung surfactants contain both saturated and unsaturated phospholipids with different lipid headgroup charges, our results suggest that when studying potential adverse effects of nanoparticles on biological systems the role of lipid compositions cannot be neglected

More than just a bracelet: the use of material symbolism to communicate love

There is growing recognition of the place of love in residential care for children (Smith, 2009). This paper is a critical analysis of a range of existing research on residential child care as well as studies of material culture and of care relationships more broadly. It argues that, despite increasing regulation and surveillance, adults and children find ways to show and feel love in the context of residential care. Whilst love may be regarded as something to be avoided or indeed prohibited in an adult/child care setting these deep bonds find expression in the everyday life of the children's home. By looking at love in this embodied way, the 'realness' of material things to assert connection and recognition of love (Layne, 2000) is examined. As Gorenstein (1996, p.8) suggests 'objects...[are] the perfect vehicles for conveying themes that are not commonly accepted in a community'. The paper emphasises the recognition of these symbolic and metaphorical forms of communication in practice

Service system planning in the presence of a random arrival rate

Service system planning in the presence of a random arrival rat

Estimating the density of a conditional expectation

Given uncertainty in the input model and parameters of a stochastic simulation study, the goal of the study often becomes the estimation of a conditional expectation. The conditional expectation is expected performance conditioned on the selected model and parameters. The density of this conditional expectation describes precisely, and concisely, the impact of input uncertainty on performance prediction. In this paper we estimate the density of a conditional expectation using ideas from the field of kernel density estimation. We show that our estimator converges under reasonable conditions and present results on optimal rates of convergence. We present two modifications of this estimator, a local estimator and a bias-corrected estimator. Convergence results are given for these estimators. We study the performance of our estimators on a number of test cases and a call center example in which the arrival process of customers is unknown.