Probabilistic analysis of cost-effectiveness models: statistical representation of parameter uncertainty

No abstract available

Perturbations of an expanding brane.

Motivated by the study of the cosmology of brane-worlds we begin by inducing vacuum decay in a 4+1 space-time assuming that the most likely configuration possesses spherical symmetry, and interpret the wall between the two vacua as a thick brane. We then set out to deduce the spectrum of perturbations about this solution with a view to making predictions about the CMB powder spectrum of such a brane. However, we find that the instability of the spherically symmetric solution causes focusing of energy at the origin, which we suggest would result in black hole formation

Bill Buxton oral history interview by Andrew Huse, September 16, 2003

Bill Buxton, a former WUSF-TV station manager who came to the university as an administrator and filmmaker in 1969, discusses the development of the TV station and how facilities have changed and improved over time. Buxton worked with many university programs to create films and many of the projects he was involved with have won Emmys. Bill Buxton still works independently with the station program

Options for putting CDS/ISIS databases on the internet

Purpose – To review the variety of software solutions available for putting CDS/ISIS databases on the internet. To help anyone considering which route to take. Approach – Briefly describes the characteristics, history, origin and availability of each package. Identifies the type of skills required to implement the package and the kind of application it is suited to. Covers CDS/ISIS Unix version, JavaISIS, IsisWWW, WWWISIS versions 3 and 5, Genisis, IAH, WWW-ISIS, and OpenIsis. Findings – There is no obvious single ‘best’ solution. Several are free but may require more investment in acquiring the skills to install and configure them. The choice will depend on the user’s experience with CDS/ISIS formatting language, HTML, programming languages, operating systems, open source software, and so on. Originality/value – There is detailed documentation available for most of these packages, but little previous guidance to help potential users to distinguish and choose between them

Population assessment of great crested newts using environmental DNA

Targeting environmental DNA (eDNA) for species monitoring and biodiversity assessment is a newly emerged technique. Surveys targeting eDNA involve the isolation of DNA shed into the environment by an organism to identify species utilizing a particular location. Despite uncertainties surrounding the technique, eDNA has begun to be used extensively for species assessments. Using the great crested newt (Triturus cristatus) as a model species, we (1) determined seasonal trends in eDNA with a view to optimising survey timing; (2) estimated the detection probabilities for eDNA and their covariates; and (3) explored how abundance estimates may be made from aquatic eDNA samples. We conclude that detection varies through the year, with most reliable detection coinciding with peak breeding. However, outside the breeding season detection is possible where larval numbers are high. Environmental and population factors may influence release of DNA from a target species or eDNA persistence in water and sediments. These include sediment type, number of both adults and larvae, changes in adult body condition, habitat variables and sampling location. As many external covariates were found to influence eDNA concentration, it would not be appropriate to use eDNA concentration as a predictor of abundance. However; we apply a modelling approach to generate estimates of abundance using genomic DNA, with a degree of accuracy deemed acceptable for ecological monitoring. The conclusions are directly relevant to refining survey design and analysis for the assessment of great crested newt populations. The results are also applicable more generally to the eDNA survey method, its development, survey design and interpretation, whether for single species analysis or community analysis

Cost-effectiveness of initial stress cardiovascular MR, stress SPECT or stress echocardiography as a gate-keeper test, compared with upfront invasive coronary angiography in the investigation and management of patients with stable chest pain: Mid-term outcomes from the CECaT randomised controlled trial

Objectives: To compare outcomes and cost-effectiveness of various initial imaging strategies in the management of stable chest pain in a long-term prospective randomised trial. Setting: Regional cardiothoracic referral centre in the east of England. Participants: 898 patients (69% man) entered the study with 869 alive at 2 years of follow-up. Patients were included if they presented for assessment of stable chest pain with a positive exercise test and no prior history of ischaemic heart disease. Exclusion criteria were recent infarction, unstable symptoms or any contraindication to stress MRI. Primary outcome measures: The primary outcomes of this follow-up study were survival up to a minimum of 2 years post-treatment, quality-adjusted survival and cost-utility of each strategy. Results: 898 patients were randomised. Compared with angiography, mortality was marginally higher in the groups randomised to cardiac MR (HR 2.6, 95% CI 1.1 to 6.2), but similar in the single photon emission CT-methoxyisobutylisonitrile (SPECT-MIBI; HR 1.0, 95% CI 0.4 to 2.9) and ECHO groups (HR 1.6, 95% CI 0.6 to 4.0). Although SPECT-MIBI was marginally superior to other non-invasive tests there were no other significant differences between the groups in mortality, quality-adjusted survival or costs. Conclusions: Non-invasive cardiac imaging can be used safely as the initial diagnostic test to diagnose coronary artery disease without adverse effects on patient outcomes or increased costs, relative to angiography. These results should be interpreted in the context of recent advances in imaging technology. Trial registration: ISRCTN 47108462, UKCRN 3696

How reliable is the habitat suitability index as a predictor of great crested newt presence or absence?

The application of a habitat suitability index (HSI) assessment to predict the use of ponds by great crested newts (Triturus cristatus) is commonly used in association with distribution and monitoring projects. Such projects are often used to inform development and planning decision making. However, this type of assessment is frequently misused, and mis interpreted. We used a large, commercially collected environmental DNA (eDNA) survey for great crested newt pond occupancy (489 ponds) to; (1) assess whether it is appropriate to use low HSI scores to rule out occupancy, (2) discuss the use of high HSI scores to identify ponds of high importance for the species and, (3) explore the eDNA detection method. We conclude that there is no evidence to support ruling out pond occupancy based on low HSI scores. However, the conventional view that ponds with HSI scores above 0.7 are of high importance to great crested newts is somewhat supported by the data. Both eDNA and direct observational survey methodologies suffer from sampling error and these need to be acknowledged in the analysis of large data sets

A variable near-infrared counterpart to the neutron-star low-mass X-ray binary 4U 1705-440

We report the discovery of a near-infrared (nIR) counterpart to the persistent neutron-star low-mass X-ray binary 4U 1705-440, at a location consistent with its recently determined Chandra X-ray position. The nIR source is highly variable, with K_s-band magnitudes varying between 15.2 and 17.3 and additional J- and H-band observations revealing color variations. A comparison with contemporaneous X-ray monitoring observations shows that the nIR brightness correlates well with X-ray flux and X-ray spectral state. We also find possible indications for a change in the slope of the nIR/X-ray flux relation between different X-ray states. We discuss and test various proposed mechanisms for the nIR emission from neutron-star low-mass X-ray binaries and conclude that the nIR emission in 4U 1705-440 is most likely dominated by X-ray heating of the outer accretion disk and the secondary star.Comment: Accepted for publication in Ap

Modeling good research practices - overview: a report of the ISPOR-SMDM modeling good research practices task force - 1.

Models—mathematical frameworks that facilitate estimation of the consequences of health care decisions—have become essential tools for health technology assessment. Evolution of the methods since the first ISPOR modeling task force reported in 2003 has led to a new task force, jointly convened with the Society for Medical Decision Making, and this series of seven papers presents the updated recommendations for best practices in conceptualizing models; implementing state–transition approaches, discrete event simulations, or dynamic transmission models; dealing with uncertainty; and validating and reporting models transparently. This overview introduces the work of the task force, provides all the recommendations, and discusses some quandaries that require further elucidation. The audience for these papers includes those who build models, stakeholders who utilize their results, and, indeed, anyone concerned with the use of models to support decision making