A universal optimization strategy for ant colony optimization algorithms based on the Physarum-inspired mathematical model

Ant colony optimization (ACO) algorithms often fall into the local optimal solution and have lower search efficiency for solving the travelling salesman problem (TSP). According to these shortcomings, this paper proposes a universal optimization strategy for updating the pheromone matrix in the ACO algorithms. The new optimization strategy takes advantages of the unique feature of critical paths reserved in the process of evolving adaptive networks of the Physarum-inspired mathematical model (PMM). The optimized algorithms, denoted as PMACO algorithms, can enhance the amount of pheromone in the critical paths and promote the exploitation of the optimal solution. Experimental results in synthetic and real networks show that the PMACO algorithms are more efficient and robust than the traditional ACO algorithms, which are adaptable to solve the TSP with single or multiple objectives. Meanwhile, we further analyse the influence of parameters on the performance of the PMACO algorithms. Based on these analyses, the best values of these parameters are worked out for the TSP.

Factors influencing compliance to universal precautions in healthcare workers: a systematic literature review

Background: Occupational exposure to blood borne viruses involving hollow bore needles is one of the most commonly reported adverse events affecting staff in the National Health Service in the UK. Universal Precautions Guidelines were originally developed in 1987 in order to minimise the risk of contact with body fluid. Universal precautions not only protect staff against blood borne pathogens but are also considered as an efficient mean to reduce the spread of pathogens from patients to patients via healthcare workers.Aim of the study: The aim of this study was to identify and evaluate the objective evidence on factors influencing healthcare workers compliance to universal precautions through a systematic literature review.Methodology: This systematic review was conducted in 2009 and studies were retrieved through electronic databases, manual journal searches and communications with experts in the field. Studies of cross sectional survey design and observational design were included in the review as they constituted the most commonly used research design evaluating compliance to universal precautions.A quality checklist was developed based on existing assessment criteria.Findings: Studies conducted to ascertain compliance to universal precautions are plentiful but remain of low quality. Sixty studies were retrieved and evaluated for potential inclusion in this study. Four studies met the inclusion criteria. Three were of cross-sectional survey design and one of direct observational design.Conclusions: Uptake of universal precautions remains low despite known benefits. Lack of time, resources and lack of knowledge have been shown as being factors negatively influencing healthcare workers compliance with universal precautions.This paper also highlights the issues surrounding the inclusion of low grade evidence in systematic literature reviews and the implications of reviews including low grade evidence on practice.Type of article: Research paperKeywords: systematic review, universal precautions, standard precautions, compliance, healthcare worker.