Valuing the benefit of varicella vaccination: comparison of willingness to pay and quality-adjusted life-years

Vaccination is different from most health interventions because it is preventative, it protects against infectious disease (leading to knock-on effects), the diseases it prevents are usually acute and self-limiting, and most vaccines are given to children from whom it is very difficult to elicit preferences. Because of its unique characteristics, vaccination may possess its own specific attributes. In this paper, we estimate the average Willingness to Pay (WTP) for varicella vaccination and the Quality-Adjusted Life-Years (QALY) lost due to chickenpox using Contingent Valuation (CV), Standard Gamble and Health Utility Index Mark II (HUI2). Furthermore, we identify what attributes of vaccination are important to vaccinees and what elicitation technique can capture these components. To do this, we administered computerised interviews to a sample of parents attending primary Health Centres. Using CV we demonstrate that individuals are willing to pay more for vaccination than treatment. Furthermore, we show that prevention of work loss is an important intervention attribute for parents. On the other hand, consistent with economic theory, the elicitation techniques used to estimate QALYs (Standard Gamble and HUI2) did not capture non-health benefits. Finally, results elicited using the CV were correlated with QALYs measured through the HUI2 questionnaire

Dust obscuration studies along quasar sight lines using simulated galaxies

We use the results of a set of three-dimensional SPH-Treecode simulations which model the formation and early evolution of disk galaxies, including the generation of heavy elements by star formation, to investigate the effects of dust absorption in quasar absorption line systems. Using a simple prescription for the production of dust, we have compared the column density, zinc abundance and optical depth properties of our models to the known properties of Damped Lyman alpha systems. We find that a significant fraction of our model galaxy disks have a higher column density than any observed DLA system. We are also able to show that such parts of the disk tend to be optically thick, implying that any background quasar would be obscured through much of the disk. This would produce the selection effect against the denser absorption systems thought to be present in observations.Comment: 7 pages, 8 figures, to be published in MNRA

The economics of health

This report presents results from the Economics of Health project funded by the East Midlands Development Agency. The work was undertaken between November 2007 and February 2008. The main aim of the project was to examine the relationship between mental and physical health and employability, labour market participation and economic performance, with specific attention given to the direction of causal relationships

The Chemical Evolution of the Universe I: High Column Density Absorbers

We construct a simple, robust model of the chemical evolution of galaxies from high to low redshift, and apply it to published observations of damped Lyman-alpha quasar absorption line systems (DLAs). The elementary model assumes quiescent star formation and isolated galaxies (no interactions, mergers or gas flows). We consider the influence of dust and chemical gradients in the galaxies, and hence explore the selection effects in quasar surveys. We fit individual DLA systems to predict some observable properties of the absorbing galaxies, and also indicate the expected redshift behaviour of chemical element ratios involving nucleosynthetic time delays. Despite its simplicity, our `monolithic collapse' model gives a good account of the distribution and evolution of the metallicity and column density of DLAs, and of the evolution of the global star formation rate and gas density below redshifts z 3. However, from the comparison of DLA observations with our model, it is clear that star formation rates at higher redshifts (z>3) are enhanced. Galaxy interactions and mergers, and gas flows very probably play a major role.Comment: 36 pages, 11 figures; accepted by MNRA

Long-term Running Experience with the Silicon Micro-strip Tracker at the D{\O} detector

The SiliconMicro-strip Tracker (SMT) at the D{\O} experiment in the Fermilab Tevatron collider has been operating since 2001. In 2006, an additional layer, referred to as 'Layer 0', was installed to improve impact parameter resolution and compensate for detector degradation due to radiation damage to the original innermost SMT layer. The SMT detector provides valuable tracking and vertexing information for the experiment. This contribution will highlight aspects of the long term operation of the SMT, including the impact of the silicon readout test-stand. Due to the full integration of the test-stand into the D{\O} trigger framework, this test-stand provides an advantageous tool for training of new experts and studying subtle effects in the SMT while minimizing impact on the global data acquisition.Comment: Proceedings of TIPP 2011 (Technology and Instrumentation for Particle Physics 2011), June 9-14 2011, Chicago, US

Metallicity Evolution in the Early Universe

Observations of the damped Lya systems provide direct measurements on the chemical enrichment history of neutral gas in the early universe. In this Letter, we present new measurements for four damped Lya systems at high redshift. Combining these data with [Fe/H] values culled from the literature, we investigate the metallicity evolution of the universe from z~1.5-4.5. Contrary to our expectations and the predictions of essentially every chemical evolution model, the N(HI)-weighted mean [Fe/H] metallicity exhibits minimal evolution over this epoch. For the individual systems, we report tentative evidence for an evolution in the unweighted [Fe/H] mean and the scatter in [Fe/H] with the higher redshift systems showing lower scatter and lower typical [Fe/H] values. We also note that no damped Lya system has [Fe/H] < -2.7 dex. Finally, we discuss the potential impact of small number statistics and dust on our conclusions and consider the implications of these results on chemical evolution in the early universe.Comment: 6 pages, 2 encapsulated figures, Latex2e, uses emulateapj.sty and onecolfloat.sty. Accepted for publication in ApJ Letters: Feb 28, 200

Experimental quantum verification in the presence of temporally correlated noise

Growth in the complexity and capabilities of quantum information hardware mandates access to practical techniques for performance verification that function under realistic laboratory conditions. Here we experimentally characterise the impact of common temporally correlated noise processes on both randomised benchmarking (RB) and gate-set tomography (GST). We study these using an analytic toolkit based on a formalism mapping noise to errors for arbitrary sequences of unitary operations. This analysis highlights the role of sequence structure in enhancing or suppressing the sensitivity of quantum verification protocols to either slowly or rapidly varying noise, which we treat in the limiting cases of quasi-DC miscalibration and white noise power spectra. We perform experiments with a single trapped $^{171}$Yb$^{+}$ ion as a qubit and inject engineered noise ($\propto \sigma^z$) to probe protocol performance. Experiments on RB validate predictions that the distribution of measured fidelities over sequences is described by a gamma distribution varying between approximately Gaussian for rapidly varying noise, and a broad, highly skewed distribution for the slowly varying case. Similarly we find a strong gate set dependence of GST in the presence of correlated errors, leading to significant deviations between estimated and calculated diamond distances in the presence of correlated $\sigma^z$ errors. Numerical simulations demonstrate that expansion of the gate set to include negative rotations can suppress these discrepancies and increase reported diamond distances by orders of magnitude for the same error processes. Similar effects do not occur for correlated $\sigma^x$ or $\sigma^y$ errors or rapidly varying noise processes, highlighting the critical interplay of selected gate set and the gauge optimisation process on the meaning of the reported diamond norm in correlated noise environments.Comment: Expanded and updated analysis of GST, including detailed examination of the role of gauge optimization in GST. Full GST data sets and supplementary information available on request from the authors. Related results available from http://www.physics.usyd.edu.au/~mbiercuk/Publications.htm