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Models where pairs, triples, or larger (typically connected) sets of sites on a 2D lattice ‘‘fill’’ irreversibly (described here as dimer, trimer, ... filling or adsorption), either randomly or cooperatively, are required to describe many surface adsorption and reaction processes. Since filling is assumed to be irreversible and immobile (species are ‘‘frozen’’ once adsorbed), even the stationary, saturation state, which is nontrivial since the lattice cannot fill completely, is not in equilibrium. The kinetics and statistics of these processes are naturally described by recasting the master equations in hierarchic form for probabilities of subconfigurations of empty sites. These hierarchies are infinite for the infinite lattices considered here, but approximate solutions can be obtained by implementing truncation procedures. Those used here exploit a shielding property of suitable walls of empty sites peculiar to irreversible filling processes. Accurate results, including saturation coverage estimates, are presented for random filling of dimers, and trimers of different shapes, on various infinite 2D lattices, and for square tetramers on an infinite square lattice. [ABSTRACT FROM AUTHOR]

Aim. This paper is a report of a study to describe the experiences of nurses who had committed serious medication errors, the meaning these experiences carry, and what kind of help and support they received after committing their error. Background. Medication administration is an important nursing task. Work overload, combined with increased numbers and dosages of medication prescribed, puts nurses at risk of making serious errors. A drug error has the potential for disastrous consequences for patients. What is sometimes disregarded is the effect on the nurse involved. The majority of research on nurses and medication errors is framed within biomedicine, law and management. Methods. An explorative, descriptive design was adopted and 10 in-depth interviews were conducted in 2003 with nurses who had committed a medication error. The text was analysed using a phenomenological method. Findings. Serious medication errors can have a great impact on nurses, both personally and professionally. Reactions from significant others were central to the final outcome for nurses who made drug errors. They wanted to share their experiences, but this required confidence and trust. Nurses were generally willing to accept responsibility for their errors. Conclusion. Strategies should be developed so that errors can be managed in a constructive manner, which includes exploring underlying causes and the counselling and support needs of the nurses involved. [ABSTRACT FROM AUTHOR]

Software architecture design approaches typically treat architecture as an abstraction of the implemented system. However, doing so means that the concepts, languages, notations, and tools for architecture are much more closely related to those of detailed design and implementation than to those of software requirements. Thus the gap between requirements and architecture represents a paradigm shift, while that between architecture and detailed design does not. Global Analysis, which is part of the Siemens Four Views architecture design approach, is a set of activities that serves to reduce the magnitude of this gap by guiding the architecture design process, capturing design rationale, and supporting traceability between requirements and architecture. In this paper Global Analysis is re-examined in light of five years of teaching it, reflecting on it, comparing it to other approaches, and examining how it was applied in four new systems. This experience confirms the value of the Global Analysis activities and the importance of capturing its results. In some cases the benefit went beyond that envisioned, and in other cases Global Analysis was not applied as expected. Because the templates that are provided for Global Analysis results have such a strong influence on how the activities were performed, this will be the focus of future changes. [ABSTRACT FROM AUTHOR]