219 research outputs found
Adenovirus-based vectors: maximizing opportunities and optimizing a rich diversity of vectors for gene-based therapy
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An investigation into the feasibility, problems and benefits of re-engineering a legacy procedural CFD code into an event driven, object oriented system that allows dynamic user interaction
This research started with questions about how the overall efficiency, reliability and ease-of-use of Computational Fluid Dynamics (CFD) codes could be improved using any available software engineering and Human Computer Interaction (HCI) techniques. Much of this research has been driven by the difficulties experienced by novice CFD users in the area of Fire Field Modelling where the introduction of performance based building regulations have led to a situation where non CFD experts are increasingly making use of CFD techniques, with varying degrees of effectiveness, for safety critical research. Formerly, such modelling has not been helped by the mode of use, high degree of expertise required from the user and the complexity of specifying a simulation case. Many of the early stages of this research were channelled by perceived limitations of the original legacy CFD software that was chosen as a framework for these investigations. These limitations included poor code clarity, bad overall efficiency due to the use of batch mode processing, poor assurance that the final results presented from the CFD code were correct and the requirement for considerable expertise on the part of users.
The innovative incremental re-engineering techniques developed to reverse-engineer, re-engineer and improve the internal structure and usability of the software were arrived at as a by-product of the research into overcoming the problems discovered in the legacy software. The incremental reengineering methodology was considered to be of enough importance to warrant inclusion in this thesis. Various HCI techniques were employed to attempt to overcome the efficiency and solution correctness problems. These investigations have demonstrated that the quality, reliability and overall run-time efficiency of CFD software can be significantly improved by the introduction of run-time monitoring and interactive solution control. It should be noted that the re-engineered CFD code is observed to run more slowly than the original FORTRAN legacy code due, mostly, to the changes in calling architecture of the software and differences in compiler optimisation: but, it is argued that the overall effectiveness, reliability and ease-of-use of the prototype software are all greatly improved. Investigations into dynamic solution control (made possible by the open software architecture and the interactive control interface) have demonstrated considerable savings when using solution control optimisation. Such investigations have also demonstrated the potential for improved assurance of correct simulation when compared with the batch mode of processing found in most legacy CFD software. Investigations have also been conducted into the efficiency implications of using unstructured group solvers.
These group solvers are a derivation of the simple point-by-point Jaccobi Over Relaxation (JOR) and Successive Over Relaxation (SOR) solvers [CROFT98] and using group solvers allows the computational processing to be more effectively targeted on regions or logical collections of cells that require more intensive computation. Considerable savings have been demonstrated for the use of both static- and dynamic- group membership when using these group solvers for a complex 3-imensional fire modelling scenario. Furthermore the improvements in the system architecture (brought about as a result of software re-engineering) have helped to create an open framework that is both easy to comprehend and extend. This is in spite of the underlying unstructured nature of the simulation mesh with all of the associated complexity that this brings to the data structures. The prototype CFD software framework has recently been used as the core processing module in a commercial Fire Field Modelling product (called "SMARTFIRE" [EWER99-1]). This CFD framework is also being used by researchers to investigate many diverse aspects of CFD technology including Knowledge Based Solution Control, Gaseous and Solid Phase Combustion, Adaptive Meshing and CAD file interpretation for ease of case specification
Screening for critical congenital heart defects with pulse oximetry: medical aspects
The detection of newborn babies with potentially life-threatening, critical congenital heart defects (CCHDs) before they collapse or expire remains an important clinical challenge. The absence of physical signs and the difficulty assessing mild cyanosis means that the newborn baby check misses up to a third of babies. Fetal anomaly ultrasound scanning identifies an increasing proportion, but this screen is operator-dependent and therefore highly variable; although some units report very high detection rates, overall most babies with CCHD are still missed. Pulse oximetry screening (POS) is an additional test that meets the criteria for universal screening. POS increases overall detection of CCHD to over 90% and also identifies babies with noncardiac, hypoxemic conditions (such as congenital pneumonia, early-onset sepsis, and pulmonary hypertension), which are usually included in the false positives. There is a wealth of published data on the POS, both in a research setting and more recently in routine clinical practice, and consideration of POS is becoming increasingly widespread particularly among high-income countries. But a degree of controversy still remains, and debate continues regarding the most appropriate time to screen, the most effective screening pathway, and screening outside the well-baby nursery. So, should all newborn babies be screened with POS, if so, when and where should screening take place, what saturations are acceptable, and which conditions are we trying to identify? This review will look at the available evidence and try to suggest the way forward for those considering its introduction into their clinical practice.</jats:p
Pulse oximetry screening for critical congenital heart defects:a life-saving test for all newborn babies
Congenital heart defects (CHD) are the commonest congenital malformations and remain a major cause of neonatal mortality and morbidity in the developed world [...
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