4,881 research outputs found
Structured grid generation for gas turbine combustion systems
Commercial pressures to reduce time-scales encourage innovation in the design and
analysis cycle of gas turbine combustion systems. The migration of Computational
Fluid Dynamics (CFD) from the purview of the specialist into a routine analysis tool is
crucial to achieve these reductions and forms the focus of this research. Two significant
challenges were identified: reducing the time-scale for creating and solving a CFD prediction
and reducing the level of expertise required to perform a prediction.
The commercial pressure for the rapid production of CFD predictions, coupled with the
desire to reduce the risk associated with adopting a new technology led, following a
review of available techniques, to the identification of structured grids as the current
optimum methodology.
It was decided that the task of geometry definition would be entirely performed within
commercial Computer Aided Design (CAD) systems. A critical success factor for this
research was the adoption of solid models for the geometry representation. Solids
ensure consistency, and accuracy, whilst eliminating the need for the designer to undertake
difficult, and time consuming, geometry repair operations. The versatility of parametric
CAD systems were investigated on the complex geometry of a combustion system and found to be useful in reducing the overhead in altering the geometry for a
CFD prediction. Accurate and robust transfer between CAD and CFD systems was
achieved by the use of direct translators.
Restricting the geometry definition to solid models allowed a novel two stage grid generator
to be developed. In stage one an initial algebraic grid is created. This reduces
user interaction to a minimum, by the employment of a series of logical rules based on
the solid model to fill in any missing grid boundary condition data. In stage two the
quality of the grid is improved by redistributing nodes using elliptical partial differential
equations. A unique approach of improving grid quality by simultaneously smoothing
both internal and surface grids was implemented. The smoothing operation was
responsible for quality, and therefore reduced the level of grid generation expertise
required.
The successful validation of this research was demonstrated using several test cases
including a CFD prediction of a complete combustion system
The development of a theory-based intervention to promote appropriate disclosure of a diagnosis of dementia
Background: The development and description of interventions to change professional practice are often limited by the lack of an explicit theoretical and empirical basis. We set out to develop an intervention to promote appropriate disclosure of a diagnosis of dementia based on theoretical and empirical work. Methods: We identified three key disclosure behaviours: finding out what the patient already knows or suspects about their diagnosis; using the actual words 'dementia' or 'Alzheimer's disease' when talking to the patient; and exploring what the diagnosis means to the patient. We conducted a questionnaire survey of older peoples' mental health teams (MHTs) based upon theoretical constructs from the Theory of Planned Behaviour (TPB) and Social Cognitive Theory (SCT) and used the findings to identify factors that predicted mental health professionals' intentions to perform each behaviour. We selected behaviour change techniques likely to alter these factors. Results: The change techniques selected were: persuasive communication to target subjective norm; behavioural modelling and graded tasks to target self-efficacy; persuasive communication to target attitude towards the use of explicit terminology when talking to the patient; and behavioural modelling by MHTs to target perceived behavioural control for finding out what the patient already knows or suspects and exploring what the diagnosis means to the patient. We operationalised these behaviour change techniques using an interactive 'pen and paper' intervention designed to increase intentions to perform the three target behaviours. Conclusion : It is feasible to develop an intervention to change professional behaviour based upon theoretical models, empirical data and evidence based behaviour change techniques. The next step is to evaluate the effect of such an intervention on behavioural intention. We argue that this approach to development and reporting of interventions will contribute to the science of implementation by providing replicable interventions that illuminate the principles and processes underlying change.This project is funded by UK Medical Research Council, Grant reference number G0300999. Jeremy Grimshaw holds a Canada Research Chair in Health Knowledge Transfer and Uptake. Jill Francis is funded by the Chief Scientist Office of the Scottish Government Health Directorate. The views expressed in this study are those of the authors
Ichthyological Bulletin of the J.L.B. Smith Institute of Ichthyology; No. 37
Lethrinops argentea Ahl, L. lethrinus (Gunther) and L. leptodon Regan are re-described and illustrated. An additional new species, L. longipinnis, sharing with the above the possession a steeply sloping, wedge-shaped snout, a slender lower pharyngeal bone and few (9—14) gillrakers is described. The status of L. lunaris Trewavas is discussed.Rhodes University Libraries (Digitisation
Ethical issues in implementation research: a discussion of the problems in achieving informed consent
Background: Improved quality of care is a policy objective of health care systems around the world. Implementation research is the scientific study of methods to promote the systematic uptake of clinical research findings into routine clinical practice, and hence to reduce inappropriate
care. It includes the study of influences on healthcare professionals' behaviour and methods to enable them to use research findings more effectively. Cluster randomized trials represent the optimal design for evaluating the effectiveness of implementation strategies. Various codes of
medical ethics, such as the Nuremberg Code and the Declaration of Helsinki inform medical research, but their relevance to cluster randomised trials in implementation research is unclear. This paper discusses the applicability of various ethical codes to obtaining consent in cluster trials in implementation research.
Discussion: The appropriate application of biomedical codes to implementation research is not obvious. Discussion of the nature and practice of informed consent in implementation research cluster trials must consider the levels at which consent can be sought, and for what purpose it can be sought. The level at which an intervention is delivered can render the idea of patient level
consent meaningless. Careful consideration of the ownership of information, and rights of access to and exploitation of data is required. For health care professionals and organizations, there is a balance between clinical freedom and responsibility to participate in research.
Summary: While ethical justification for clinical trials relies heavily on individual consent, for
implementation research aspects of distributive justice, economics, and political philosophy underlie the debate. Societies may need to trade off decisions on the choice between individualized consent and valid implementation research. We suggest that social sciences codes could usefully inform the consideration of implementation research by members of Research Ethics Committees
Species identity dominates over environment in shaping the microbiota of small mammals
The mammalian gut microbiota is considered pivotal to host fitness, yet the determinants of community composition remain poorly understood. Laboratory studies show that environmental factors, particularly diet, are important, while comparative work emphasises host genetics. Here, we compare the influence of host genetics and the environment on the microbiota of sympatric small mammal species (mice, voles, shrews) across multiple habitats. While sharing a habitat caused some microbiota convergence, the influence of species identity dominated. In all three host genera examined, an individual's microbiota was more similar to conspecifics living elsewhere than to heterospecifics at the same site. Our results suggest this species‐specificity arises in part through host‐microbe codiversification. Stomach contents analysis suggested that diet also shapes the microbiota, but where diet is itself influenced by species identity. In this way, we can reconcile the importance of both diet and genetics, while showing that species identity is the strongest predictor of microbiota composition
‘It's a double whammy’ A qualitative study of illness uncertainty in individuals with Parkinson's disease in the context of COVID-19
Objectives: The purpose of this study was to explore the experiences of individuals with Parkinson's through the theoretical lens of illness uncertainty during the first UK full lockdown period (March–June 2020) put in place due outbreak of the COVID-19 pandemic. Methods: Individual semi-structured interviews were carried out via telephone in May 2020 with 10 individuals with Parkinson's (six men and four women) recruited from Parkinson's UK. Interviews were recorded and transcribed verbatim, and thematic analysis was adopted to analyse the resulting data. Results: Four overarching themes emerged from the interview data: (1) COVID-19 amplifying existing fears and difficulties around the uncertainty of Parkinson's; (2) practical and psychological efforts to manage uncertainty; (3) benefit-finding as a way of acknowledging the positives of lockdown; (4) risk and future management in the context of uncertainty. Discussion: Participants reported a range of implicit and explicit strategies to cope with the ‘double whammy’ of uncertainty caused by having Parkinson's during a global pandemic. While these were generally successful in maintaining well-being, it is important that such successful accounts are used to help inform novel strategies and interventions targeting individuals who might need additional support
Impact of CONSORT extension for cluster randomised trials on quality of reporting and study methodology : review of random sample of 300 trials, 2000-8
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