Efficient Design and Inference for Multi-stage Randomized Trials of Individualized Treatment Policies

Increased clinical interest in individualized ‘adaptive’ treatment policies has shifted the methodological focus for their development from the analysis of naturalistically observed strategies to experimental evaluation of a pre-selected set of strategies via multi-stage designs. Because multi-stage studies often avoid the ‘curse of dimensionality’ inherent in uncontrolled studies, and hence the need to parametrically smooth trial data, it is not surprising in this context to find direct connections among different methodological approaches. We show by asymptotic and algebraic proof that the maximum likelihood (ML) and optimal semi-parametric estimators of the mean of a treatment policy and its standard error are equal under certain experimental conditions. The two methodologies offer conceptually different formulations, which we exploit to develop a unified and efficient approach to design and inference for multi-stage trials of policies that adapt treatment according to discrete responses. We derive a sample size formula expressed in terms of a parametric (regression-based) version of the optimal semi-parametric population variance. Non-parametric (sample-based) ML estimation performed well in simulation studies, in terms of achieved power, even though sample sizes relied on parametric re-expression. For a variety of simulated scenarios, ML outperformed the semi-parametric approach, which used a priori rather than estimated randomization probabilities, because the test statistic was sensitive to even small differences arising in finite samples

Exploring heritage through time and space : Supporting community reflection on the highland clearances

On the two hundredth anniversary of the Kildonan clearances, when people were forcibly removed from their homes, the Timespan Heritage centre has created a program of community centred work aimed at challenging pre conceptions and encouraging reflection on this important historical process. This paper explores the innovative ways in which virtual world technology has facilitated community engagement, enhanced visualisation and encouraged reflection as part of this program. An installation where users navigate through a reconstruction of pre clearance Caen township is controlled through natural gestures and presented on a 300 inch six megapixel screen. This environment allows users to experience the past in new ways. The platform has value as an effective way for an educator, artist or hobbyist to create large scale virtual environments using off the shelf hardware and open source software. The result is an exhibit that also serves as a platform for experimentation into innovative ways of community co-creation and co-curation.Postprin

Effects of low-level dietary microalgae supplementation on the distal intestinal microbiome of farmed rainbow trout Oncorhynchus mykiss (Walbaum)

In this study, high throughput 16S rRNA sequencing was used to investigate the effect of a novel whole-cell dietary microalgae meal (Schizochytrium limacinum), on the distal intestinal microbiome of farmed rainbow trout, Oncorhynchus mykiss. Heterotrophic microalgae are rich in omega 3 polyunsaturated fatty acids, can be produced sustainably and have been shown to have beneficial effects on host health. After a 15-week trial period, microbial community profiles were compared between the distal intestinal contents of fish fed either a control diet or a treatment diet that partially replaced fish oil with microalgae meal, at a substitution level of 5%. The results of this research showed that the microbial communities of both fish populations were composed of similar microbial taxa, however, the treatment group fed the microalgae supplement possessed a greater level of microbial diversity than those in the control group. A limited number of bacterial taxa were discriminatory between diets and were significantly elevated in the treatment group, notably operational taxonomic units (OTUs) assigned to the genera Streptococcus, Leuconostoc, Lactobacillus, Lactococcus and Weissella. However, the overall structure of the intestinal microbiome between control and treatment groups was not found to be significantly different. The treatment group displayed a heavier mean weight and condition factor at the end of the trial period. The results of this study suggest that the tested microalgae meal can be used as a replacement for a proportion of fish oil in aquafeeds, with minor changes to the intestinal microbiome of farmed rainbow trout, and positive effects on growth

Evidence for quantum confinement in the photoluminescence of porous Si and SiGe

We have used anodization techniques to process porous surface regions in p-type Czochralski Si and in p-type Si0.85Ge0.15 epitaxial layers grown by molecular beam epitaxy. The SiGe layers were unrelaxed before processing. We have observed strong near-infrared and visible light emission from both systems. Analysis of the radiative and nonradiative recombination processes indicate that the emission is consistent with the decay of excitons localized in structures of one or zero dimensions

How are They Spending my Taxes? Tax Compliance and Citizens’ Interest in Politics

In neoclassical economics, individuals are assumed to perceive tax payments as commensurate with any other payment. This paper challenges this assumption. Individuals are more likely to identify with the community when they pay a higher share of their income in tax and when compliance is also an expression of civic duty. An analysis of questionnaire responses from over 20 countries suggests that citizens take a greater interest in politics when they are more tax compliant

Self administered cognitive screening test (TYM) for detection of Alzheimer’s disease: cross sectional study

Objective To evaluate a cognitive test, the TYM (“test your memory”), in the detection of Alzheimer’s disease

Assessing the performance of ZigBee in a reverberant environment using a mode stirred chamber

The application of ZigBee networks to highly reverberant environments has been investigated using a reverberation chamber. Different Q-factors were set up, by loading the reverberation chamber, and the performance of a COTS ZigBee system was recorded. It has been found that the ZigBee system tested is capable of working in highly reverberant environments and is only seriously limited for a value of Q-factor above 5000, which is greater than that which would typically be encountered outside of a laboratory. The packet error rate (PER) was generally found to be very low for Q-factors between 1000 and 5000, with the possibility a high PER for same combinations of stirrer and antenna positions. With a Q of below 1000 the transceivers were found to work with a PER below 1% regardless of antenna and stirrer positions and the corresponding fading is nearly flat over a data symbol's bandwidth. Radio performance is presented in terms of the packet error rate and this is related to the measured and simulated channel impulse response