Ergonomists as designers: computational modelling and simulation of complex socio-technical systems.

Contemporary ergonomics problems are increasing in scale, ambition, and complexity. Understanding and creating solutions for these multi-faceted, dynamic, and systemic problems challenges traditional methods. Computational modelling approaches can help address this methodological shortfall. We illustrate this potential by describing applications of computational modelling to: (1) teamworking within a multi-team engineering environment; (2) crowd behaviour in different transport terminals; and (3) performance of engineering supply chains. Our examples highlight the benefits and challenges for multi-disciplinary approaches to computational modelling, demonstrating the need for socio-technical design principles. Our experience highlights opportunities for ergonomists as designers and users of computational models, and the instrumental role that ergonomics can play in developing and enhancing complex socio-technical systems. Recognising the challenges inherent in designing computational models, we reflect on practical issues and lessons learned so that computational modelling and simulation can become a standard and valuable technique in the ergonomists' toolkit. Practitioner summary: This paper argues that computational modelling and simulation is currently underutilised in ergonomics research and practice. Through example applications illustrating the benefits, limitations, and opportunities of such approaches, this paper is a point of reference for researchers and practitioners using computational modelling to explore complex socio-technical systems.

Systems scenarios: a tool for facilitating the socio-technical design of work systems.

The socio-technical systems approach to design is well documented. Recognising the benefits of this approach, organisations are increasingly trying to work with systems, rather than their component parts. However, few tools attempt to analyse the complexity inherent in such systems, in ways that generate useful, practical outputs. In this paper, we outline the 'System Scenarios Tool' (SST), which is a novel, applied methodology that can be used by designers, end-users, consultants or researchers to help design or re-design work systems. The paper introduces the SST using examples of its application, and describes the potential benefits of its use, before reflecting on its limitations. Finally, we discuss potential opportunities for the tool, and describe sets of circumstances in which it might be used. Practitioner Summary: The paper presents a novel, applied methodological tool, named the 'Systems Scenarios Tool'. We believe this tool can be used as a point of reference by designers, end-users, consultants or researchers, to help design or re-design work systems. Included in the paper are two worked examples, demonstrating the tool's application.

Photoinduced ligand isomerisation in a pyrazine-containing ruthenium polypyridyl complex.

Photochemically-induced ligand rearrangements for the N2 and N4 coordination isomers of the complex [Ru(bpy)(2)(Hpztr)](2+) and its deprotonated analogue [Ru(bpy)(2)(pztr)](+), where bpy is 2,2'-bipyridyl and Hpztr is pyrazine-1,2,4-triazole ligand, are reported. (1)H NMR spectroscopic and HPLC studies indicate that in acetone and acetonitrile the complexes are photostable when the triazole ring is deprotonated. Irradiation of the protonated N2 isomer in acetone results in formation of the N4 isomer, with the N4 isomer being photostable. In acetonitrile both isomers show photolability of the triazole-based ligand and full dissociation to form [Ru(bpy)(2)(CH(3)CN)(2)](2+) is observed. The activation parameters for the population of the (3)MC state from the lowest (3)MLCT manifold, as obtained from temperature-dependent emission lifetime studies, are reported and their relevance to the observed photochemical behaviour is considered. The results obtained are discussed in relation the analogous pyridine-triazole complexes.

Electronic properties of Ru(II) complexes bound to a bisphenolate bridge with low lying pi* orbitals.

The synthesis and a detailed investigation into the electronic properties of mononuclear and dinuclear Ru(II) complexes of the ligand bis(2-hydroxyphenyl)-2,5-dihydropyrazine (H(2)BHD) is described. In these complexes the Ru(II) moieties are bound through O,N coordination to an anionic phenolate and the pyrazine bridge. Relatively few reports are available on the dinuclear complexes bridged across a phenolate and this study provides an opportunity to examine the impact of reduced oxygen donor ligands on metal-metal communication. The results presented here reveal some very unusual behavior whereby the apparent location of the LUMO changes between the mononuclear and dinuclear complexes. The lowest energy optical transition appears to involve the peripheral bipyridine ligand as acceptor in the mononuclear complex, whereas this ligand is not involved in the lowest energy optical transition in the dinuclear complex. The origin of this difference is not clear, however, significant changes in the electronic properties of the mononuclear complex are observed on coordination of the second metal, reflected in significant alterations in the electrochemistry of the bridge and metals as well as changes in the optical spectroscopy. The BHD(2-) bridge is shown to support weakly coupled class II behavior according to the Robin and Day classification, reflected in a K(c) of 335.