Following a companion paper on analytical methods, this paper presents simulation as a complementary method for analyzing the reliability of water distribution networks. For this simulation, the distribution system is modeled as a network whose pipes and pumps are subject to failure. Nodes are targeted to receive a given supply at a given head. If this head is not attainable, supply at the node is reduced. Pumps and pipes fail randomly, according to probability distributions with userspecified parameters. Several reliability measures are estimated with this simulation. Confidence intervals are also supplied for some of these reliability measures. Simulation results are presented for a small network (ten nodes) and a larger network (sixteen nodes). Simulation enables computation of a much broader class of reliability measures than do analytical methods, but it requires considerably more computer time and its results are less easy to generalize. It is therefore recommended that analytical and simulation methods be used together when assessing the reliability of a system arid considering improvements.

The writers express their great appreciation to the authors for comprehensive presentation of the complex issue of evaluating multiobjective programing techniques. The purpose of this comment is to discuss several human factor problems related to multiobjective interactive programing approaches that were not considered in the authors' paper. CONTINUOUS OR DISCRETEThe authors made a crucial assumption for the evaluation that 'water resource problems... are usually characterized by an infinite number of possible alternatives .... '[Cohon and Marks, 1975, p.• 215]. In fact, real world planning problems may be discrete as well as continuous. The continuous representations are often used in sizing and scheduling the operation of systems with known structure; but the discrete approach is almost 'classical' in structuring large systems, where the number of possible alternatives is almost always finite. Then, geography and orography allow only a small discrete

This review of key studies in the quality and safety literature discusses the current state-of-play of implementation science applied to these domains.

Producing energy resources requires significant quantities of fresh water. As an energy sector changes or expands, the mix of technologies deployed to produce fuels and electricity determines the associated burden on regional water resources. Many reports have identified the water consumption of various energy production technologies. This paper synthesizes and expands upon this previous work by exploring the geographic distribution of water use by national energy portfolios. By defining and calculating an indicator to compare the water consumption of energy production for over 150 countries, we estimate that approximately 52 billion cubic meters of fresh water is consumed annually for global energy production. Further, in consolidating the data, it became clear that both the quality of the data and global reporting standards should be improved to track this important variable at the global scale. By introducing a consistent indicator to empirically assess coupled water-energy systems, it is hoped that this research will provide greater visibility into the magnitude of water use for energy production at the national and global scales.

Objectives:Performance indicators are a popular mechanism for measuring the quality of healthcare to facilitate both quality improvement and systems management. Few studies make comparative assessments of different countries’ performance indicator frameworks. This study identifies and compares frameworks and performance indicators used in selected Organisation for Economic Co-operation and Development health systems to measure and report on the performance of healthcare organisations and local health systems. Countries involved are Australia, Canada, Denmark, England, the Netherlands, New Zealand, Scotland and the United States.Methods:Identification of comparable international indicators and analyses of their characteristics and of their broader national frameworks and contexts were undertaken. Two dimensions of indicators – that they are nationally consistent (used across the country rather than just regionally) and locally relevant (measured and reported publicly at a local level, for example, a health service) – were deemed important.Results:The most commonly used domains in performance frameworks were safety, effectiveness and access. The search found 401 indicators that fulfilled the ‘nationally consistent and locally relevant’ criteria. Of these, 45 indicators are reported in more than one country. Cardiovascular, surgery and mental health were the most frequently reported disease groups.Conclusion:These comparative data inform researchers and policymakers internationally when designing health performance frameworks and indicator sets.