Variable selection and updating in model-based discriminant analysis for high dimensional data with food authenticity applications

Food authenticity studies are concerned with determining if food samples have been correctly labelled or not. Discriminant analysis methods are an integral part of the methodology for food authentication. Motivated by food authenticity applications, a model-based discriminant analysis method that includes variable selection is presented. The discriminant analysis model is fitted in a semi-supervised manner using both labeled and unlabeled data. The method is shown to give excellent classification performance on several high-dimensional multiclass food authenticity datasets with more variables than observations. The variables selected by the proposed method provide information about which variables are meaningful for classification purposes. A headlong search strategy for variable selection is shown to be efficient in terms of computation and achieves excellent classification performance. In applications to several food authenticity datasets, our proposed method outperformed default implementations of Random Forests, AdaBoost, transductive SVMs and Bayesian Multinomial Regression by substantial margins

On Setting Near-term Climate Policy while the Dust Begins to Settle: The Legacy of the Stern Review

We review the explosion of commentary that has followed the release of the Stern Review: The Economics of Climate Change, and agree with most of what has been written. The Review is right when it argues on economic grounds for immediate intervention to reduce emissions of greenhouse gases, but we feel that it is right for the wrong reasons. A persuasive case can be made that climate risks are real and increasingly threatening. If follows that some sort of policy will be required, and the least cost approach necessarily involves starting now. Since policy implemented in 2007 will not “solve” the climate problem, near term interventions can be designed to begin the process by working to avoid locking in high carbon investments and providing adequate incentives for carbon sequestration. We argue that both objectives can be achieved without undue economic harm in the near term by pricing carbon at something on the order of $15 per ton as long as it is understood that the price will increase persistently and predictably at something like the rate of interest; and we express support for a tax alternative to the usual cap-and-trade approach.Stern Review, climate change, climate policy, social discount rate; risk and equity aversion

Single shot, temporally and spatially resolved measurements of fast electron dynamics using a chirped optical probe

A new approach to rear surface optical probing is presented that permits multiple, time-resolved 2D measurements to be made during a single, ultra-intense ( > 1018 W cm−2) laser-plasma interaction. The diagnostic is capable of resolving rapid changes in target reflectivity which can be used to infer valuable information on fast electron transport and plasma formation at the target rear surface. Initial results from the Astra-Gemini laser are presented, with rapid radial sheath expansion together with detailed filamentary features being observed to evolve during single shots

Apparatus for investigating resonance with application to magnetic resonance imaging

Citation: Murphy, S., Jones, D. L., Gross, J., & Zollman, D. (2015). Apparatus for investigating resonance with application to magnetic resonance imaging. American Journal of Physics, 83(11), 942-947. doi:10.1119/1.4928177Resonance is typically studied in the context of either a pendulum or a mass on a spring. We have developed an apparatus that enables beginning students to investigate resonant behavior of changing magnetic fields, in addition to the properties of the magnetic field due to a wire and the superposition of magnetic fields. In this resonant system, a compass oscillates at a frequency determined by the compass's physical properties and an external magnetic field. While the analysis is mathematically similar to that of the pendulum, this apparatus has an advantage that the magnetic field is easily controlled, while it is difficult to control the strength of gravity. This apparatus has been incorporated into a teaching module on magnetic resonance imaging. (C) 2015 American Association of Physics Teachers

Some Dimensions of Leadership Behavior of School Superintendents in Selected Texas School Districts

The problem of this study was an investigation of some dimensions of leadership behavior of Texas school superintendents as perceived by themselves and as perceived by their staffs

‘It’s like I have this weird superpower’: experiences of detectable and undetectable viral load among a cohort of recently diagnosed people living with HIV.

Background: By reducing HIV viral load to undetectable levels, HIV treatment slows disease progression and eliminates the possibility of sexual transmission. The promotion of undetectable viral load has also been accompanied by expectations of reducing HIV-related stigma, including self-stigma. Drawing on accounts of people recently diagnosed with HIV, we explored experiences of both detectable and undetectable viral load. Methods: Between January 2019 and November 2021, semi-structured interviews were conducted with 35 people living with HIV (PLHIV) who had received an HIV diagnosis in Australia from 2016 onward. Of these participants, 24 completed follow-up interviews approximately 12 months later. Interviews were transcribed verbatim, entered into NVivo (software v12), and thematically analysed. Results: Reflecting on the period in which their viral load was detectable, some participants described feeling ‘dirty,’ ‘viral,’ and ‘a risk’ to sexual partners. During this period, some participants minimised or ceased having sex, sometimes despite being in ongoing romantic relationships. Reaching undetectable viral load was commonly characterised as an important goal in HIV care and signalled a marker of good health and enabled a return to sexual relationships. However, the psychosocial benefits of undetectable viral load were not universally experienced, with some participants highlighting ongoing challenges of living with HIV long term. Conclusions: Increasing awareness of the benefits of undetectable viral load is an important and powerful tool for improving the health and wellbeing of PLHIV; however, the period in which one’s HIV viral load is detectable can be challenging, particularly as feelings of being ‘unclean’ and ‘a risk’ may be internalised. Ensuring PLHIV are appropriately supported during periods of viral detectability is necessary

Novel application of synchrotron x-ray computed tomography for ex-vivo imaging of subcutaneously-injected polymeric microsphere suspension formulations

Purpose: Subcutaneously or intramuscularly administered biodegradable microsphere formulations have been successfully exploited in the management of chronic conditions for over two decades, yet mechanistic understanding of the impact of formulation attributes on in vivo absorption rate from such systems is still in its infancy. Methods: Suspension formulation physicochemical attributes may impact particulate deposition in subcutaneous (s.c.) tissue. Hence, the utility of synchrotron X-ray microcomputed tomography (μCT) for assessment of spatial distribution of suspension formulation components (PLG microspheres and vehicle) was evaluated in a porcine s.c. tissue model. Optical imaging of dyed vehicle and subsequent microscopic assessment of microsphere deposition was performed in parallel to compare the two approaches. Results: Our findings demonstrate that synchrotron μCT can be applied to the assessment of microsphere and vehicle distribution in s.c. tissue, and that microspheres can also be visualised in the absence of contrast agent using this approach. The technique was deemed superior to optical imaging of macrotomy for the characterisation of microsphere deposition owing to its non-invasive nature and relatively rapid data acquisition time. Conclusions: The μCT method outlined in this study provides a novel insight into the relative distribution of vehicle and suspended PLG microspheres following s.c. injection. A potential application for our findings is understanding the impact of injection, device and formulation variables on initial and temporal depot geometry in pre-clinical or ex-vivo models that can inform product design

Women’s experiences of over-the-counter and prescription medication during pregnancy in the UK: findings from survey free-text responses and narrative interviews

OBJECTIVES: To explore women's experiences of over-the-counter and prescription medication advice and use during pregnancy. DESIGN: A study design consisting of an online survey and nested in-depth interviews with a subsample of participants. We analysed data from survey free-text responses and in-depth interviews using thematic analysis. Quantitative survey data is published elsewhere.The UK. PARTICIPANTS: Women were eligible if living in the UK, aged 16-45 years, were pregnant or had been pregnant in the last 5 years regardless of pregnancy outcome. A total of 7090 women completed the survey, and 34 women who collectively had experienced 68 pregnancies were subsequently interviewed. RESULTS: Medication prescribing and use during pregnancy was common. The prescribing, dispensing and taking of some advised medications were restricted through women's or prescribers' fear of fetal harm. Lack of adherence to national prescribing guidance, conflicting professional opinion and poor communication resulted in maternal anxiety, avoidable morbidity and women negotiating complex and distressing pathways to obtain recommended medications. In contrast, some women felt overmedicated and that pharmacological treatments were used without exploring other options first. CONCLUSION: Increased translation of national guidance into practice and greater personalisation of antenatal care are needed to improve the safety, efficacy and personalisation of prescribing in pregnancy