Ontological considerations of time, meta-predicates and temporal propositions

A natural approach to representing and reasoning about temporal propositions (i.e., statements with time-dependent truth-values) is to associate them with time elements. In the literature, there are three choices regarding the primitive for the ontology of time: (1) instantaneous points, (2) durative intervals and (3) both points and intervals. Problems may arise when one conflates different views of temporal structure and questions whether some certain types of temporal propositions can be validly and meaningfully associated with different time elements. In this paper, we shall summarize an ontological glossary with respect to time elements, and diversify a wider range of meta-predicates for ascribing temporal propositions to time elements. Based on these, we shall also devise a versatile categorization of temporal propositions, which can subsume those representative categories proposed in the literature, including that of Vendler, of McDermott, of Allen, of Shoham, of Galton and of Terenziani and Torasso. It is demonstrated that the new categorization of propositions, together with the proposed range of meta-predicates, provides the expressive power for modeling some typical temporal terms/phenomena, such as starting-instant, stopping-instant, dividing-instant, instigation, termination and intermingling etc.

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.