Unsupervised learning for anomaly detection in Australian medical payment data

Fraudulent or wasteful medical insurance claims made by health care providers are costly for insurers. Typically, OECD healthcare organisations lose 3-8% of total expenditure due to fraud. As Australia’s universal public health insurer, Medicare Australia, spends approximately $A 34 billion per annum on the Medicare Benefits Schedule (MBS) and Pharmaceutical Benefits Scheme, wasted spending of$A1–2.7 billion could be expected.However, fewer than 1% of claims to Medicare Australia are detected as fraudulent, below international benchmarks. Variation is common in medicine, and health conditions, along with their presentation and treatment, are heterogenous by nature. Increasing volumes of data and rapidly changing patterns bring challenges which require novel solutions. Machine learning and data mining are becoming commonplace in this field, but no gold standard is yet available. In this project, requirements are developed for real-world application to compliance analytics at the Australian Government Department of Health and Aged Care (DoH), covering: unsupervised learning; problem generalisation; human interpretability; context discovery; and cost prediction. Three novel methods are presented which rank providers by potentially recoverable costs. These methods used association analysis, topic modelling, and sequential pattern mining to provide interpretable, expert-editable models of typical provider claims. Anomalous providers are identified through comparison to the typical models, using metrics based on costs of excess or upgraded services. Domain knowledge is incorporated in a machine-friendly way in two of the methods through the use of the MBS as an ontology. Validation by subject-matter experts and comparison to existing techniques shows that the methods perform well. The methods are implemented in a software framework which enables rapid prototyping and quality assurance. The code is implemented at the DoH, and further applications as decision-support systems are in progress. The developed requirements will apply to future work in this fiel

Exercise-induced bronchoconstriction: The effects of montelukast, a leukotriene receptor antagonist

Exercise-induced bronchoconstriction (EIB) is very common in both patients with asthma and those who are otherwise thought to be normal. The intensity of exercise as well as the type of exercise is important in producing symptoms. This may make some types of exercise such as swimming more suitable and extended running more difficult for patients with this condition. A better understanding of EIB will allow the physician to direct the patient towards a type of exercise and medications that can result in a more active lifestyle without the same concern for resulting symptoms. This is especially important for schoolchildren who are usually enrolled in physical education classes and elite athletes who may desire to participate in competitive sports. Fortunately several medications (short- and long-acting β2-agonists, cromolyn, nedocromil, inhaled corticosteroids, and more recently leukotriene modifiers) have been shown to be effective in preventing or attenuating the effects of exercise in many patients. In addition, inhaled β2-agonists have been shown to quickly reverse the airway obstruction that develops in patients and continue to be the reliever medications of choice. Inhaled corticosteroids are increasingly being recommended as regular therapy now that the role of inflammation and airway injury has been identified in EIB. With the discovery that there is a release of mediators such as histamine and leukotrienes from cells in the airway following exercise with resulting airway obstruction in susceptible individuals, interest has turned to attenuating their effects with mediator antagonists especially those that block the effects of leukotrienes. Studies with an oral leukotriene antagonist, montelukast, have shown beneficial effects in adults and children aged as young as 6 years with EIB. These effects can be demonstrated as soon as two hours and as long as 24 hours after administration without a demonstrated loss of a protective effect after months of treatment. The studies leading up to and resulting in an approval of montelukast for EIB for patients aged 15 years and older are reviewed in this paper

Purification and identification of placental histaminase

Saline extracts were made from desanguinated human placentae, and histaminase was purified from these extracts by salt fractionation, ion-exchange chromatography on cellulosic adsorbents, and by gel filtration on Sephadex G-200. The Specific Activity of the preparation increased approximately 800- fold from Stage 1 to Stage 6, part of this increase being due to the removal of enzyme inhibitors. Further attempts to resolve Stage 6 enzyme by ion-exchange chromatography and re-cycling gel filtration removed some of the remaining contaminants, but did not result in further increases in Specific Activity. Starch gel electrophoresis of the purest preparation revealed that the enzyme had not been separated from high-molecular weight haptoglobin-methaemoglobin species. A new spectrophotometric test for histaminase was developed from Kapeller-Adler 's (1951) indigo test, which proved unsuitable for the present work. The new test was about 50 times more sensitive than any previous method measuring a common product of oxidative deamination of all substrates. Extinction changes after 24. hr. incubation were linearly related to enzyme concentration. Zeller's criticisms of indigo tests (1956, 1965) could not be substantiated. The new indigo test gave very similar results to the method of Holmstedt and Tham (1959) in almost all applications. Although the oxidation of substrate and the production of hydrogen peroxide proceeded immediately, indigometric assays were subject to an initial delay in indigo oxidation, lasting several hours. The oxidation of indigo by synthetic hydrogen peroxide was not subject to any delayj the mechanisms of indigo oxidation by synthet c hydrogen peroxide and by hydrogen peroxide produced in the enzyme-substrate reaction were not the same. More than the stoichiometric amount of indigo was oxidised in tests using synthetic or enzymic hydrogen peroxide, due to oxidation by atmospheric oxygen, catalysed by substrates and products of the indigo test. No way was found to eliminate, or correct results for, hyper-stoichiometric indigo oxidation, and therefore rates of oxidation of indigo could not be translated into conventional expressions of enzymic activity. The specificity of the purest preparations of placental histaminase was found to resemble that of hog kidney and pea seedling DAO, With supporting evidence from mixed-substrate experiments, it was concluded that histaminase oxidised not only the aliphatic diamines, but also agmatine, benzylamine and histamine. Activity towards histamine could not have been due to any known contaminant. The Michaelis constants for the oxidation of several substrates by placental histaminase were determined. Km for putrescine, and the appearance of an optimal substrate concentration, varied with the assay method employed. The histamine concentration giving optimal activity was lower than that for hog kidney DAO. The pH optima for the activity of placental histaminase towards several substrates were determined. The inhibitor specificity of placental histaminasa resembled that of hog kidney and pea seedling DAO, but was distinct from that of benzylamine oxidase or monoamine oxidase (MAO). Activity towards the aliphatic diamines, but not towards histamine, tended to diminish as the enzyme was purified, unless EDTA wa3 added to the working buffers. The possible significance of metal ions in the activation and inhibition of histaminase was discussed, and it was suggested that discrepancies in earlier reports on the specificity of hog kidney DAO might be due to contamination of enzyme solutions by metal ions. Contamination of the purest preparation by other proteins precluded detailed study of the cofactors of placental histaminase, but the possible involvement of copper and pyridoxal phosphate was discussed. The molecular weight of histaminase x*as probably at least 200,000. The enzyme was much more thermolabile than hog kidney MO, but it was extremely stable at low temperatures in dilute borate buffer, pH 8.6. Priorities for future work were considered to be: (a) Development of a satisfactory assay method for oxidative deamination, (b) Separation of histaminase from haptoglobin-methaemoglobin. (c) Study of the metabolism of aliphatic diamines in normal and pregnant human subjects

Design Of A Collimated Line Source For Transmission Ct Imaging Of The Head With A Spect System

Single photon emission computed tomography (SPECT) has the potential to provide absolute quantitative information about the function of an organ. However, two factors which limit accurate quantification are the attenuation of the gamma rays emitted from the radiopharmaceutical concentration and the inability to define the anatomic region being quantified. Presented in this thesis is an attenuation correction that compensates SPECT brain images for attenuation and a transmission imaging system that (a) provides the distribution of attenuation coefficients required for the attenuation compensation and (b) simplifies regional identification by registering the functional SPECT images onto the anatomic transmission images. The attenuation correction algorithm is an exact compensation for a radiopharmaceutical concentration that is evenly distributed throughout the brain tissue and completely surrounded by an attenuating, nonradioactive bone medium. It explicitly corrects projections of the brain for bone and tissue attenuation and it improves the uniformity and increases the count density of the resulting SPECT images. The transmission CT imaging system consists of a collimated line source and a conventional SPECT camera equipped with a fan beam collimator (FBC). In the transverse image plane the resolution of the transmission system is equal to the intrinsic camera resolution ({dollar}\approx{dollar}4mm), but resolution in the longitudinal plane (coincident to the axis of rotation of the SPECT camera), without the line source collimator, is characterized by the camera and FBC resolutions ({dollar}\approx{dollar}8mm at 150mm above the collimator). The line source collimator (LSC) is a one-dimensional collimator that improves the longitudinal resolution of the system. Computer simulations were used to design a LSC that provided the system with isotropic resolution ({dollar}\approx{dollar}4mm in image plane) while maximizing the geometric efficiency. The attenuation compensation algorithm requires that the skull attenuation coefficient and thickness be known, and images of the human head demonstrated that this information can be measured using the transmission imaging system. However, due to limitations of the present SPECT system, a brain SPECT image that has been attenuation corrected with the techniques described herein is not presented. Finally, a mathematical formalism to compute the geometric modulation transfer function of a transmission imaging system with parallel hole collimation was derived. The formalism is a valuable tool in the design of such transmission systems and it replaces the need to use computer intensive simulations to predict the system resolution.;In this thesis I have demonstrated the feasibility of acquiring transmission CT images with a SPECT system. The transmission images will be used to determine the attenuation coefficients for the attenuation correction and registration of the SPECT brain images to anatomical images, thereby improving the quantification of regional cerebral blood flow

Processing of Preceramic Polymers for Direct-Ink Writing

Preceramic polymers are organosilicon polymers that, when pyrolyzed to above 1000°C, convert from a polymer to an amorphous ceramic. These polymers have been used for fiber spinning, polymer infiltration, and casting of materials but have recently gained interest for use as the feedstock material for additive manufacturing techniques. This work explores preceramic polymers being used for direct-ink writing (an additive manufacturing method) and many of the issues that occur with the polymers during curing and pyrolysis. The first chapter of this dissertation provides a review of preceramic polymers, while the second and third chapters focus on the development of inks made of preceramic polymers. The second chapter uses a polysilazane polymer mixed with up to 43.3 volume percent hexagonal boron nitride as the rheological modifier to enable printing. The pyrolyzed parts are tested with 3-point flexure and microhardness indentation to observe failure behavior. The third chapter uses a polycarbosilane polymer with zirconium diboride and silicon carbide fibers as constituents for printable inks. These polycarbosilane-based inks exhibit much more porosity and crack development during curing and pyrolysis than the inks in the second chapter. Defects are characterized with micro-computed tomography and scanning electron microscopy. From the measured defects, new suggestions for decreasing porosity and crack development are discussed. Building from the observations in the third chapter, the fourth chapter focuses on how the size of printed material influences the development of defects and overall strength. Two new inks, similar to those in chapter three, are used with the addition that one of the formulations utilizes fumed alumina as an added viscosity modifier. The final study investigates printed rods of varying diameters (0.45 to 1.7 millimeter) to observe the effects of off-gassing during curing on the development of porosity. Failure strength is measured with 3-point flexure and Weibull statistics are used to understand how specimen size and ink formulation affect final specimen strength. Overall, this dissertation shows that preceramic polymers are a viable option as a feedstock material for direct ink-writing and begins to quantify the degree to which part size and filler selection affect overall porosity development after curing and pyrolysis

Compositions Combining Acoustic, Electro-Acoustic And Synthetic Instruments For Modern Jazz Performance

Compositions Combining Acoustic, Electro-acoustic and Synthetic Instruments for Modern Jazz Performance presents a series of seven compositions by vibraphonist and composer David Kemp. The seven works primarily explore combining acoustic (trumpet and drums), electro-acoustic (electric guitar, bass guitar and pickup equipped vibraphone) and synthetic (electronically created synthesizer patches on a Roland XV5050 Sound Module) instruments, mixing musical styles, using rhythm and duration as a governing force in composition, using an extensive harmonic palette and incorporating technology. In this document, the scores are presented in full in a Portfolio Volume, accompanied by recorded performances in audio and visual formats and written analyses of the compositions. Included is a discussion of archetypal composers, similar stylistic traits of their music to mine, and conclusions drawn from the project. The document is completed by a bibliography and discography