731 research outputs found
Trends in Emission Standards and the Implications for Bus Fleet Management: Technology Assessment for Brisbane Transport
Cities around the world have set ambitious emissions reduction targets. They are promoting public transport in order to reduce urban pollution from the transportation sector. Cleaner and less polluting city transit buses are paramount if cities are to attain their ambitious emissions reduction targets, as transit buses are high usage vehicles that operate in heavily congested areas where air quality improvements and reductions in public exposure to harmful air contaminants are critical. Decision to invest in a new bus is based on the cost, technology and emission standards. Frequent changes in the emission standards and evolution of bus technology adds to the uncertainty in decision making. A bus has a life expectancy of about 20 years-during its lifespan if the emission standards change and the bus can no longer satisfy the requirements then it has to be phased out or upgraded to comply with the emission requirements-which costs money and time thus leading to financial and service losses. The objective of a decision maker while investing is to optimize the returns of investments-low costs and lower emissions. This paper will look at the Brisbane Transport as a case study-the aim of this paper is to perform comparative technology assessment and based on that provide recommendations to the Brisbane Transport fleet manager during the selection of new buses, in order to attain the 2026 patronage and emissions targets set by Brisbane
Sample size calculations for cluster randomised controlled trials with a fixed number of clusters
Background\ud
Cluster randomised controlled trials (CRCTs) are frequently used in health service evaluation. Assuming an average cluster size, required sample sizes are readily computed for both binary and continuous outcomes, by estimating a design effect or inflation factor. However, where the number of clusters are fixed in advance, but where it is possible to increase the number of individuals within each cluster, as is frequently the case in health service evaluation, sample size formulae have been less well studied. \ud
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Methods\ud
We systematically outline sample size formulae (including required number of randomisation units, detectable difference and power) for CRCTs with a fixed number of clusters, to provide a concise summary for both binary and continuous outcomes. Extensions to the case of unequal cluster sizes are provided. \ud
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Results\ud
For trials with a fixed number of equal sized clusters (k), the trial will be feasible provided the number of clusters is greater than the product of the number of individuals required under individual randomisation () and the estimated intra-cluster correlation (). So, a simple rule is that the number of clusters () will be sufficient provided: \ud
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> x \ud
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Where this is not the case, investigators can determine the maximum available power to detect the pre-specified difference, or the minimum detectable difference under the pre-specified value for power. \ud
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Conclusions\ud
Designing a CRCT with a fixed number of clusters might mean that the study will not be feasible, leading to the notion of a minimum detectable difference (or a maximum achievable power), irrespective of how many individuals are included within each cluster. \ud
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Niche divergence in a brown lemur (' Eulemur ' spp.) hybrid zone : using ecological niche models to test models of stability
A systematic map of research exploring the effect of greenspace on mental health
The past 35 years has seen an accumulation of empirical evidence suggesting a positive association between greenspace and mental health. Existing reviews of evidence are narrow in scope, and do not adequately represent the broad range of disciplines working in this field. This study is the first systematic map of studies investigating greenspace effects on mental health. A total of 6059 papers were screened for their relevance, 276 of which met inclusion criteria for the systematic map.The map revealed several methodological limitations hindering the practical applications of research findings to public health. Critically, the majority of studies used cross-sectional mental health data which makes causal inference about greenspace effects challenging. There are also few studies on the micro-features that make up greenspaces (i.e., their “quality”), with most focussing only on “quantity” effects on mental health. Moreover, few studies adopted a multi-scale approach, meaning there is little evidence about at which spatial scale(s) the relationship exists. A geographic gap in study location was also identified, with the majority of studies clustered in European countries and the USA.Future research should account for both human and ecological perspectives of “quality” using objective and repeatable measures, and consider the potential of scale-dependent greenspace effects to ensure that management of greenspace is compatible with wider scale biodiversity targets. To establish the greenspace and metal health relationship across a life course, studies should make better use of longitudinal data, as this enables stronger inferences to be made than more commonly used cross-sectional data
A review of consumer awareness, understanding and use of food-based dietary guidelines
Copyright @ 2011 Cambridge University PressFood-based dietary guidelines (FBDG) have primarily been designed for the consumer to encourage healthy, habitual food choices, decrease chronic disease risk and improve public health. However, minimal research has been conducted to evaluate whether FBDG are utilised by the public. The present review used a framework of three concepts, awareness, understanding and use, to summarise consumer evidence related to national FBDG and food guides. Searches of nine electronic databases, reference lists and Internet grey literature elicited 939 articles. Predetermined exclusion criteria selected twenty-eight studies for review. These consisted of qualitative, quantitative and mixed study designs, non-clinical participants, related to official FBDG for the general public, and involved measures of consumer awareness, understanding or use of FBDG. The three concepts of awareness, understanding and use were often discussed interchangeably. Nevertheless, a greater amount of evidence for consumer awareness and understanding was reported than consumer use of FBDG. The twenty-eight studies varied in terms of aim, design and method. Study quality also varied with raw qualitative data, and quantitative method details were often omitted. Thus, the reliability and validity of these review findings may be limited. Further research is required to evaluate the efficacy of FBDG as a public health promotion tool. If the purpose of FBDG is to evoke consumer behaviour change, then the framework of consumer awareness, understanding and use of FBDG may be useful to categorise consumer behaviour studies and complement the dietary survey and health outcome data in the process of FBDG evaluation and revision.This study is funded by the European Commission Sixth Framework Programme (contract no. 036196)
Social and Environmental Factors Associated with Preschoolers' Non-sedentary Physical Activity
The two-fold purpose of the investigation was (1) to describe with direct observation data the physical
activity behaviors and the accompanying social and environmental events of those behaviors for children in preschools; and (2) to determine which contextual conditions were predictors of moderate-to-vigorous physical activity (MVPA) and non-sedentary physical activity (i.e., light activity + MVPA) for 3-, 4-, and 5-year-old children during their outdoor play. The results indicate that preschoolers' physical activity is characterized as sedentary in nature throughout their preschool day (i.e., 89% sedentary, 8% light activity, 3% MVPA). During outdoor play periods, when children are most likely to be physically active, some contextual and social circumstances better predict their physical activity. Implications for policymakers, practitioners, and researchers are discussed. Originally published Child Development, Vol. 80, No. 1, Jan/Feb 200
Cross-docking: A systematic literature review
This paper identifies the major research concepts, techniques, and models covered in the cross-docking literature. A systematic literature review is conducted using the BibExcel bibliometric analysis and Gephi network analysis tools. A research focus parallelship network (RFPN) analysis and keyword co-occurrence network (KCON) analysis are used to identify the primary research themes. The RFPN results suggest that vehicle routing, inventory control, scheduling, warehousing, and distribution are most studied. Of the optimization and simulation techniques applied in cross-docking, linear and integer programming has received much attention. The paper informs researchers interested in investigating cross-docking through an integrated perspective of the research gaps in this domain. This paper systematically reviews the literature on cross-docking, identifies the major research areas, and provides a survey of the techniques and models adopted by researchers in the areas related to cross-docking
Leaf traits interact with management and water table to modulate ecosystem properties in fen peatlands
Aims Trade-offs between slow and fast nutrient turnover rates among plants may affect soil properties and biomass production. We examined how plant traits interact with abiotic variables to modulate ecosystem properties (soil C, soil C/N ratio, aboveground biomass) in peatlands. Methods We determined the interacting effects of abiotic variables (vegetation management, water table height) and leaf traits (specific leaf area, leaf dry-matter content, leaf C/N ratio) on ecosystem properties in two lowland fens in East Anglia, UK using structural equation modelling. Results Our models explained between 21% and 95% of the variability in ecosystem properties. Leaf traits directly influenced soil nutrient content and plant biomass and mediated the effects of abiotic variables on ecosystem properties. Abiotic variables exerted larger effects on ecosystem properties among herbaceous communities, but leaf traits were equally important when modelling all communities in combination. Conclusions The expected trade-offs between exploitative and conservative life strategies among species scaled-up to changes in soil properties and biomass production, even in fen habitats where abiotic variables play an important role through marked seasonal variations. Our findings suggest an important role of leaf economics in the functioning of fens, but their effects on ecosystems may be highly dependent on local conditions
The process of setting micronutrient recommendations: a cross-European comparison of nutrition-related scientific advisory bodies
Copyright @ The Authors 2010Objective: To examine the workings of the nutrition-related scientific advisory bodies in Europe, paying particular attention to the internal and external contexts within which they operate. Design: Desk research based on two data collection strategies: a questionnaire completed by key informants in the field of micronutrient recommendations and a case study that focused on mandatory folic acid (FA) fortification. Setting: Questionnaire-based data were collected across thirty-five European countries. The FA fortification case study was conducted in the UK, Norway, Denmark, Germany, Spain, Czech Republic and Hungary. Results: Varied bodies are responsible for setting micronutrient recommendations, each with different statutory and legal models of operation. Transparency is highest where there are standing scientific advisory committees (SAC). Where the standing SAC is created, the range of expertise and the terms of reference for the SAC are determined by the government. Where there is no dedicated SAC, the impetus for the development of micronutrient recommendations and the associated policies comes from interested specialists in the area. This is typically linked with an ad hoc selection of a problem area to consider, lack of openness and transparency in the decisions and over-reliance on international recommendations. Conclusions: Even when there is consensus about the science behind micronutrient recommendations, there is a range of other influences that will affect decisions about the policy approaches to nutrition-related public health. This indicates the need to document the evidence that is drawn upon in the decisions about nutrition policy related to micronutrient intake.This work has been carried out within the EURRECA Network of Excellence (www.eurreca.org) which is financially supported by the Commission of the European Communities, specific Research, Technology and Development (RTD) Programme Quality of Life and Management of Living Resources, within the Sixth Framework Programme, contract no. 036196
Changing micronutrient intake through (voluntary) behaviour change. The case of folate.
The objective of this study was to relate behaviour change mechanisms to nutritionally relevant behaviour and demonstrate how the different mechanisms can affect attempts to change these behaviours. Folate was used as an example to illuminate the possibilities and challenges in inducing behaviour change. The behaviours affecting folate intake were recognised and categorised. Behaviour change mechanisms from "rational model of man", behavioural economics, health psychology and social psychology were identified and aligned against folate-related behaviours. The folate example demonstrated the complexity of mechanisms influencing possible behavioural changes, even though this only targets the intake of a single micronutrient. When considering possible options to promote folate intake, the feasibility of producing the desired outcome should be related to the mechanisms of required changes in behaviour and the possible alternatives that require no or only minor changes in behaviour. Dissecting the theories provides new approaches to food-related behaviour that will aid the development of batteries of policy options when targeting nutritional problems
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