Detecting a rotation in the epsilon Eridani debris disc

The evidence for a rotation of the epsilon Eridani debris disc is examined. Data at 850 micron wavelength were previously obtained using the Submillimetre Common User Bolometer Array (SCUBA) over periods in 1997-1998 and 2000-2002. By chi-square fitting after shift and rotation operations, images from these two epochs were compared to recover proper motion and orbital motion of the disc. The same procedures were then performed on simulated images to estimate the accuracy of the results. Minima in the chi-square plots indicate a motion of the disc of approximately 0.6'' per year in the direction of the star's proper motion. This underestimates the true value of 1'' per year, implying that some of the structure in the disc region is not associated with epsilon Eridani, originating instead from background galaxies. From the chi-square fitting for orbital motion, a counterclockwise rotation rate of ~2.75 degrees per year is deduced. Comparisons with simulated data in which the disc is not rotating show that noise and background galaxies result in approximately Gaussian fluctuations with a standard deviation +/-1.5 degrees per year. Thus counterclockwise rotation of disc features is supported at approximately a 2-sigma level, after a 4-year time difference. This rate is faster than the Keplerian rate of 0.65 degrees per year for features at ~65 AU from the star, suggesting their motion is tracking a planet inside the dust ring. Future observations with SCUBA-2 can rule out no rotation of the epsilon Eridani dust clumps with ~4-sigma confidence. Assuming a rate of about 2.75 degrees per year, the rotation of the features after a 10-year period could be shown to be >1 degree per year at the 3-sigma level.Comment: 8 pages, 6 figure

Effect of pressure on the quantum spin ladder material IPA-CuCl3

Inelastic neutron scattering and bulk magnetic susceptibility studies of the quantum S=1/2 spin ladder system IPA-CuCl3 are performed under hydrostatic pressure. The pressure dependence of the spin gap $\Delta$ is determined. At $P=1.5$ GPa it is reduced to $\Delta=0.79$ meV from $\Delta=1.17$ meV at ambient pressure. The results allow us to predict a soft-mode quantum phase transition in this system at P$_\mathrm{c}\sim 4$ GPa. The measurements are complicated by a proximity of a structural phase transition that leads to a deterioration of the sample.Comment: 5 pages, 4 figure

Obituary

Volume: XVI

Virtual patients designed for training against medical error: Exploring the impact of decision-making on learner motivation.

OBJECTIVES: Medical error is a significant cause of patient harms in clinical practice, but education and training are recognised as having a key role in minimising their incidence. The use of virtual patient (VP) activities targeting training in medical error allows learners to practice patient management in a safe environment. The inclusion of branched decision-making elements in the activities has the potential to drive additional generative cognitive processing and improved learning outcomes, but the increased cognitive load on learning risks negatively affecting learner motivation. The aim of this study is to better understand the impact that the inclusion of decision-making and inducing errors within the VP activities has on learner motivation. METHODS: Using a repeated study design, over a period of six weeks we provided undergraduate medical students at six institutions in three countries with a series of six VPs written around errors in paediatric practice. Participants were divided into two groups and received either linearly structured VPs or ones that incorporated branched decision-making elements. Having completed all the VPs, each participant was asked to complete a survey designed to assess their motivation and learning strategies. RESULTS: Our analysis showed that in general, there was no significant difference in learner motivation between those receiving the linear VPs and those who received branched decision-making VPs. The same results were generally reflected across all six institutions. CONCLUSIONS: The findings demonstrated that the inclusion of decision-making elements did not make a significant difference to undergraduate medical students' motivation, perceived self-efficacy or adopted learning strategies. The length of the intervention was sufficient for learners to overcome any increased cognitive load associated with branched decision-making elements being included in VPs. Further work is required to establish any immediate impact within periods shorter than the length of our study or upon achieved learning outcomes