Exploitation of symbolic information in interprocedural dependence analysis

The requirement for a very accurate dependence analysis to underpin software tools to aid the generation of efficient parallel implementations of scalar code is argued. The current status of dependence analysis is shown to be inadequate for the generation of efficient parallel code, causing too many conservative assumptions to be made. This paper summarises the limitations of conventional dependence analysis techniques, and then describes a series of extensions which enable the production of a much more accurate dependence graph. The extensions include analysis of symbolic variables, the development of a symbolic inequality disproof algorithm and its exploitation in a symbolic Banerjee inequality test; the use of inference engine proofs; the exploitation of exact dependence and dependence pre-domination attributes; interprocedural array analysis; conditional variable definition tracing; integer array tracing and division calculations. Analysis case studies on typical numerical code is shown to reduce the total dependencies estimated from conventional analysis by up to 50%. The techniques described in this paper have been embedded within a suite of tools, CAPTools, which combines analysis with user knowledge to produce efficient parallel implementations of numerical mesh based codes.

Nursing resources and patient outcomes in intensive care: a systematic review of the literature

Objectives: To evaluate the empirical evidence linking nursing resources to patient outcomes in intensive care settings as a framework for future research in this area. Background: Concerns about patient safely and the quality of care are driving research on the clinical and cost-effectiveness of health care interventions, including the deployment of human resources. This is particularly important in intensive care where a large proportion of the health care budget is consumed and where nursing staff is the main item of expenditure. Recommendations about staffing levels have been trade but may not be evidence based and may not always be achieved in practice. Methods: We searched systematically for studies of the impact of nursing resources (e.g. nurse-patient ratios, nurses' level of education, training and experience) on patient Outcomes, including mortality and adverse events, in adult intensive care. Abstracts of articles were reviewed and retrieved if they investigated the relationship between nursing resources and patient Outcomes. Characteristics of the studies were tabulated and the quality of the Studies assessed. Results: Of the 15 studies included in this review, two reported it statistical relationship between nursing resources and both mortality and adverse events, one reported ail association to mortality only, seven studies reported that they Could not reject the null hypothesis of no relationship to mortality and 10 studies (out of 10 that tested the hypothesis) reported a relationship to adverse events. The main explanatory mechanisms were the lack of time for nurses to perform preventative measures, or for patient surveillance. The nurses' role in pain control was noted by One author. Studies were mainly observational and retrospective and varied in scope from 1 to 52 units. Recommendations for future research include developing the mechanisms linking nursing resources to patient Outcomes, and designing large multi-centre prospective Studies that link patient's exposure to nursing care oil a shift-by-shift basis over time. (C) 2007 Elsevier Ltd. All rights reserved.