The rp Process Ashes from Stable Nuclear Burning on an Accreting Neutron Star

We calculate the nucleosynthesis during stable nuclear burning on an accreting neutron star. This is appropriate for weakly magnetic neutron stars accreting at near-Eddington rates in low mass X-ray binaries, and for most accreting X-ray pulsars. We show that the nuclear burning proceeds via the rapid proton capture process (rp process), and makes nuclei far beyond the iron group. The final mixture of nuclei consists of elements with a range of masses between approximately A=60 and A=100. The average nuclear mass of the ashes is set by the extent of helium burning via (alpha,p) reactions, and depends on the local accretion rate. Our results imply that the crust of these accreting neutron stars is made from a complex mixture of heavy nuclei, with important implications for its thermal, electrical and structural properties. A crustal lattice as impure as our results suggest will have a conductivity set mostly by impurity scattering, allowing more rapid Ohmic diffusion of magnetic fields than previously estimated.Comment: To appear in the Astrophysical Journal (33 pages, LaTeX, including 11 postscript figures

Construction of Gold Micro-Bead Ultramicroelectrodes

A new way to construct small electrodes by the use of metal micro-beads is described. Gold beads of 1.5 to 3.0 mm diameter were used to construct inexpensive and disposable microelectrodes with overall structural diameters of £ 6 mm and electrode diameters of £ 5 mm. The voltammetric response of these electrodes is consistent with existing theory and the electrodes exhibited the sigmoidal waves expected at ultramicroelectrodes

VARIATION IN LANDING DURING GYMNASTICS SKILLS

The aim of this study was to examine joint motion during landing from a variety of gymnastics skills. Twelve gymnasts performed a range of gymnastics skills with a landing component. Joint angles of the ankle, knee and hip were examined during landing from five different skills. There were significant differences between skills at all joints for peak flexion and extension (ankle, knee and hip:

METHOD FOR THE DETECTION OF FATIGUE DURING GYMNASTICS TRAINING

The purpose of this study was to determine if acceleration measured at the pelvis was a suitable indicator of fatigue in gymnasts. Fourteen gymnasts performed vertical jumps and drop landings pre and post a fatiguing jumping activity. Peak acceleration during landing for jumps and drops increased significantly after fatiguing activity. Acceleration is a tool that can be collected with limited disruption to gymnastics training and an increase in peak acceleration during landing of simple jumps appears to be a useful tool for determining whether gymnasts are fatigued

METHOD FOR ANALYSING THE RISK OF OVERUSE INJURY IN GYMNASTICS

The purpose of this study was to propose and assess a method for the evaluation of all loads experienced during gymnastics training. The method is based on the measurement of acceleration on the gymnast. Twelve gymnasts performed a range of gymnastics skills with an impact component. Ground reaction forces and acceleration at the pelvis were measured. There were significant correlations between peak GRF and peak acceleration during landing from gymnastics skills for individual participants. This testing showed the potential for this method to be applied in a study of injury risk factors outside the laboratory environment. At present, this relationship means that acceleration can be used as an estimation of force, after calibrating acceleration to ground reaction force for the individual

Assessment of Resident Doctors’ Perception of Postgraduate Medical Education in Nigeria Using the SPEED Tool: A Pilot Study

Background: Obtaining feedback from trainees is important in the evaluation and evolution of Postgraduate Medical Education (PME), and policies made based on their felt needs would go a long way in making residency training a worthwhile experience. This pilot study aimed to assess resident doctors’ perception of the training content, atmosphere, and organization using the Scan of Postgraduate Educational Environment Domains (SPEED) tool. Methodology: This was a cross-sectional study conducted amongst resident doctors at Babcock University Teaching Hospital (BUTH) in Nigeria, between May and August 2019. A self-administered questionnaire was used to collect participants’ sociodemographic data, their perception of PME in their respective departments, as well as the strengths and weaknesses of the training programmes. Validity and reliability indices were assessed, and descriptive, inferential, and correlational analyses were run where appropriate. Results: The mean score for the resident doctors’ perception of training content, atmosphere, and organization was 4.0 ± 0.4, 4.2 ± 0.5 and 3.69 ± 0.60 respectively, out of a maximum of 5, indicating a positive perception of training in BUTH. The major strengths perceived by most residents were good inter-personal relations between residents and their trainers, as well as conducive learning and work environment; while the weaknesses include poor remuneration and limited staffing which hampers rotations. Conclusion: Resident doctors in BUTH mostly had a positive outlook on their training. This study serves as a reference point for local policy change (in BUTH), and a framework from which future studies on PME can emerge

Does early surgery improve outcomes for periprosthetic fractures of the hip and knee? : A systematic review and meta-analysis

Open access via Springer Compact AgreementPeer reviewedPublisher PD

Periodic Thermonuclear X-ray Bursts from GS 1826-24 and the Fuel Composition as a Function of Accretion Rate

We analyze 24 type I X-ray bursts from GS 1826-24 observed by the Rossi X-ray Timing Explorer between 1997 November and 2002 July. The bursts observed between 1997-98 were consistent with a stable recurrence time of 5.74 +/- 0.13 hr. The persistent intensity of GS 1826-24 increased by 36% between 1997-2000, by which time the burst interval had decreased to 4.10 +/- 0.08 hr. In 2002 July the recurrence time was shorter again, at 3.56 +/- 0.03 hr. The bursts within each epoch had remarkably identical lightcurves over the full approx. 150 s burst duration; both the initial decay timescale from the peak, and the burst fluence, increased slightly with the rise in persistent flux. The decrease in the burst recurrence time was proportional to Mdot^(-1.05+/-0.02) (where Mdot is assumed to be linearly proportional to the X-ray flux), so that the ratio alpha between the integrated persistent and burst fluxes was inversely correlated with Mdot. The average value of alpha was 41.7 +/- 1.6. Both the alpha value, and the long burst durations indicate that the hydrogen is burning during the burst via the rapid-proton (rp) process. The variation in alpha with Mdot implies that hydrogen is burning stably between bursts, requiring solar metallicity (Z ~ 0.02) in the accreted layer. We show that solar metallicity ignition models naturally reproduce the observed burst energies, but do not match the observed variations in recurrence time and burst fluence. Low metallicity models (Z ~ 0.001) reproduce the observed trends in recurrence time and fluence, but are ruled out by the variation in alpha. We discuss possible explanations, including extra heating between bursts, or that the fraction of the neutron star covered by the accreted fuel increases with Mdot.Comment: 9 pages, 6 figures, accepted by ApJ. Minor revisions following the referee's repor

Cosmic cookery : making a stereoscopic 3D animated movie.

This paper describes our experience making a short stereoscopic movie visualizing the development of structure in the universe during the 13.7 billion years from the Big Bang to the present day. Aimed at a general audience for the Royal Society's 2005 Summer Science Exhibition, the movie illustrates how the latest cosmological theories based on dark matter and dark energy are capable of producing structures as complex as spiral galaxies and allows the viewer to directly compare observations from the real universe with theoretical results. 3D is an inherent feature of the cosmology data sets and stereoscopic visualization provides a natural way to present the images to the viewer, in addition to allowing researchers to visualize these vast, complex data sets. The presentation of the movie used passive, linearly polarized projection onto a 2m wide screen but it was also required to playback on a Sharp RD3D display and in anaglyph projection at venues without dedicated stereoscopic display equipment. Additionally lenticular prints were made from key images in the movie. We discuss the following technical challenges during the stereoscopic production process; 1) Controlling the depth presentation, 2) Editing the stereoscopic sequences, 3) Generating compressed movies in display speci¯c formats. We conclude that the generation of high quality stereoscopic movie content using desktop tools and equipment is feasible. This does require careful quality control and manual intervention but we believe these overheads are worthwhile when presenting inherently 3D data as the result is signi¯cantly increased impact and better understanding of complex 3D scenes