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We consider the life cycle of an axisymmetric laminar thermal starting from the initial condition of a Gaussian buoyant blob. We find that, as time progresses, the thermal transitions through a number of distinct stages, undergoing several morphological changes before ending up as a vortex ring. Whilst each stage is interesting in its own right, one objective of this study is to set out a consistent mathematical framework under which the entire life cycle can be studied. This allows examination of the transition between the different stages, as well as shedding light on some unsolved questions from previous works. We find that the early stages of formation are key in determining the properties of the final buoyant vortex ring and that, since they occur on a time scale where viscosity has little effect, the final properties of the ring display an independence above a critical Reynolds number. We also find that rings consistently contain the same proportion of the initial heat and have a consistent vorticity flux. By considering the effect of Prandtl number, we show that thermal diffusion can have a significant impact on development, smoothing out the temperature field and inhibiting the generation of vorticity. Finally, by considering the wake left behind as well as the vortex ring that is generated, we observe that the wake can itself roll up to form a second mushroom cap and subsequently a secondary vortex ring that follows the first.
Laser–solid interactions are highly suited as a potential source of high energy X-rays for nondestructive imaging. A bright, energetic X-ray pulse can be driven from a small source, making it ideal for high resolution X-ray radiography. By limiting the lateral dimensions of the target we are able to confine the region over which X-rays are produced, enabling imaging with enhanced resolution and contrast. Using constrained targets we demonstrate experimentally a
X-ray source, improving the image quality compared to unconstrained foil targets. Modelling demonstrates that a larger sheath field envelope around the perimeter of the constrained targets increases the proportion of electron current that recirculates through the target, driving a brighter source of X-rays.
The analysis of cements and ores has been studied using the Applied Research Laboratories, Inc. Production Control X-ray Quantometer (PXQ), Elements included in the program were magnesium, aluminum, silicon, phosphorus, calcium and iron. The PXQ, utilizing the polychromator concept, allows the simultaneous determination of the listed elements.
Focusing ADP, EDT, quartz and LiF crystals were used with flow Geigers or Multitrons. Helium paths were used as required. The choice of crystals, detectors, and slit widths was determined to give optimum results for each element.
The effects of briquetting and ratioing to scattered background on accuracy were studied. Various instrumental factors such as helium flow rate, detector gas flow rate, short and long term stability were also investigated.
The aim of this study was to describe patient level costing methods and develop a database of healthcare resource use and cost in patients with AHF receiving ventricular assist device (VAD) therapy.
Patient level micro-costing was used to identify documented activity in the years preceding and following VAD implantation, and preceding heart transplant for a cohort of seventy-seven consecutive patients listed for heart transplantation (2009–12). Clinician interviews verified activity, established time resource required for each activity, and added additional undocumented activities. Costs were sourced from the general ledger, salary, stock price, pharmacy formulary data, and from national medical benefits and prostheses lists. Linked administrative data analyses of activity external to the implanting institution, used National Weighted Activity Units (NWAU), 2014 efficient price, and admission complexity cost weights and were compared with micro-costed data for the implanting admission.
The database produced includes patient level activity and costs associated with the seventy-seven patients across thirteen resource areas including hospital activity external to the implanting center. The median cost of the implanting admission using linked administrative data was $246,839 (interquartile range [IQR] $246,839–$271,743), versus $270,716 (IQR $211,740–$378,482) for the institutional micro-costing (p = .08).
Linked administrative data provides a useful alternative for imputing costs external to the implanting center, and combined with institutional data can illuminate both the pathways to transplant referral and the hospital activity generated by patients experiencing the terminal phases of heart failure in the year before transplant, cf-VAD implant, or death.