Coagulation equations with mass loss

Models for coagulation with mass loss arising, for example, from industrial processes in which growing inclusions are lost from the melt by colliding with the wall of the vessel are derived and solved. A variety of loss laws and a variety of coagulation kernels are considered, exact results derived where possible, and more generally the equations are reduced and solved by similarity solutions valid in the large-time limit. One notable result is the effect that mass removal has on gelation: for small loss rates, gelation is delayed, whilst above a critical threshold, gelation is completely prevented. Finally, by forming an exact explicit solution for a more general initial cluster-size distribution function, it is shown how numerical results from earlier work can be interpreted in the light of the theory presented herein.     

Edge detection in medical images using a genetic algorithm

An algorithm is developed that detects well-localized, unfragmented, thin edges in medical images based on optimization of edge configurations using a genetic algorithm (GA). Several enhancements were added to improve the performance of the algorithm over a traditional GA. The edge map is split into connected subregions to reduce the solution space and simplify the problem. The edge-map is then optimized in parallel using incorporated genetic operators that perform transforms on edge structures. Adaptation is used to control operator probabilities based on their participation. The GA was compared to the simulated annealing (SA) approach using ideal and actual medical images from different modalities including magnetic resonance imaging (MRI), computed tomography (CT), and ultrasound. Quantitative comparisons were provided based on the Pratt figure of merit and on the cost-function minimization. The detected edges were thin, continuous, and well localized. Most of the basic edge features were detected. Results for different medical image modalities are promising and encourage further investigation to improve the accuracy and experiment with different cost functions and genetic operators.     

Nicotine nasal spray with nicotine patch for smoking cessation: randomised trial with six year follow up

OBJECTIVE: To evaluate the efficacy of using a nicotine patch for 5 months with a nicotine nasal spray for 1 year. DESIGN: Placebo controlled, double blind trial. SETTING: Reykjavik health centre. SUBJECTS: 237 smokers aged 22-66 years living in or around Reykjavik. INTERVENTIONS: Nicotine patch for 5 months with nicotine nasal spray for 1 year (n=118) or nicotine patch with placebo spray (n=119). Treatment with patches included 15 mg of nicotine for 3 months, 10 mg for the fourth month, and 5 mg for the fifth month, whereas nicotine in the nasal spray was available for up to 1 year. Both groups received supportive treatment. MAIN OUTCOME MEASURE: Sustained abstinence from smoking. RESULTS: Sustained abstinence rates for the patch and nasal spray group and patch only group were 51% v 35% after 6 weeks (odds ratio 1.97, 95% confidence interval 1.17% to 3.32; P=0.011(chi2), 37% v 25% after 3 months (1.76, 1.01 to 3.08; P=0.045), 31% v 16% after 6 months (2.40, 1.27 to 4.50; P=0.005), 27% v 11% after 12 months (3.03, 1.50 to 6.14; P=0.001), and 16% v 9% after 6 years (2.09, 0.93 to 4.72; P=0.08) [corrected]. CONCLUSIONS: Short and long term abstinence rates show that the combination of using a nicotine patch for 5 months with a nicotine nasal spray for 1 year is a more effective method of stopping smoking than using a patch only. The low percentage of participants using the nasal spray at 1 year, and the few relapses during the second year, suggest that it is not cost effective to use a nasal spray for longer than 7 months after stopping a patch.     

The Recording of Echocardiograms with an Intensity-Modulated Ink-Jet Oscillograph

Echocardiography is today well established and has gained widespread acceptance as a clinical routine method, especially for the diagnosis of mitral valve stenosis. Since heart structure movements are relatively fast, only information of limited medical value can be obtained from direct inspection of the A-scope display. Ideally, an apparatus for recording the movements of heart structures in the form of curves should record multiple reflected echoes and should also be able to record simultaneously other heart parameters such as ECG, phonocardiogram, or blood pressure.     

Utilisation of geothermal energy in Iceland

The present and future uses of geothermal energy in Iceland are reviewed. The classification of geothermal areas is mentioned and their potential estimated. High temperature areas may be able to sustain the production of 20 MW/km² of electricity for at least 50 years. The potential of the 17 high temperature areas is almost 6000 MW, which is substantially greater than that of the 250 low temperature areas. However, practically all the hot water used for district heating and greenhouse farming is supplied by low temperature areas. About half the population of Iceland enjoys geothermal district heating at the cost of 35% that of comparable fuel oil heating. Utilisation of high temperature areas is relatively recent. Saturated steam from these areas is used for industrial purpose and a 60 MW geothermal power plant is being constructed.     

The high power impulse magnetron sputtering discharge as an ionized physical vapor deposition tool

Various magnetron sputtering tools have been developed that provide a high degree of ionization of the sputtered vapor referred to as ionized physical vapor deposition (IPVD). The ions can be controlled with respect to energy and direction as they arrive to the growth surface which allows for increased control of film properties during growth. Here, the design parameters for IPVD systems are briefly reviewed. The first sputter based IPVD systems utilized a secondary plasma source between the target and the substrate in order to generate a highly ionized sputtered vapor. High power impulse magnetron sputtering (HiPIMS) is a recent sputtering technique that utilizes IPVD where a high density plasma is created by applying high power pulses at low frequency and low duty cycle to a magnetron sputtering device. A summary of the key experimental findings for the HiPIMS discharge is given. Measurements of the temporal and spatial behavior of the plasma parameters indicate electron density peak, that expands from the target with a fixed velocity. The discharge develops from an inert sputtering gas dominated to a sputtered vapor dominated during the pulse. The high electron density results in a high degree of ionization of the deposition material.     

Sub-imaging technique to improve phase only filter search capability

A novel application of a phase only filter model, which is implementable in the optical domain, is proposed. In this application, automated target tracking is accomplished with a novel sub-imaging technique with correlation tracking inside a radius of interest. In this technique the image is subdivided and the correlation is tracked by comparing only the autocorrelation of the filter with itself. A radius of interest is used to reduce the number of computations required to track a moving target. Real-world video images are used to demonstrate the performance of the model.     

Production testing in miravalles geothermal field, Costa Rica

Wellbore deposition of calcium carbonate has occurred in the first wells drilled in the Miravalles geothermal field, Costa Rica. Well PGM-1 was flowtested for periods of 1, 5 and 6 months in 1980, 1981 and 1982, respectively. The well is 1300 m deep and produces from a liquid-dominated reservoir at about 240°C. The flowtests illustrate the time behavior of wells suffering from wellbore deposition. At early time the decrease in output flow rate and wellhead pressure is slow but at late time it becomes rapid; the curves are concave down. The ratio (flow rate/wellhead pressure) remains nearly constant with time for wells suffering calcium carbonate wellbore deposition, at least in the Miravalles geothermal field.