Structure and superconductivity of LiFeAs

The lithium ions in Lithium iron arsenide phases with compositions close to LiFeAs have been located using powder neutron diffraction. These phases exhibit superconductivity at temperatures at least as high as 16 K demonstrating that superconductivity in compounds with [FeAs]- anti-PbO-type anionic layers occurs in compounds with at least three different structure types and occurs for a wide range of As-Fe-As bond angles.Comment: 3 pages, 3 figures, 3 table

Augmentative and alternative communication (AAC) training provision for professionals in England

Purpose The purpose of this paper is to document augmentative and alternative communication (AAC) training provision by clinical services in England. Design/methodology/approach A questionnaire was used to obtain the following information concerning AAC training provision; frequency, length, type, content and cost, trainee occupations and numbers, and future training priorities, and information concerning training providers – service type, geographical area. Findings In total, 98 clinical service training providers in England responded. Services commonly reported providing AAC training to speech and language therapists, teaching assistants and teachers. Training around “use of specific AAC products, systems and technology” and “introducing/awareness raising of AAC products” were rated as high priority for future training and were two of the three subject areas where services reported the highest percentage of training. Training was predominantly provided at a foundation (basic) level. Originality/value There is no consensus on the amount or content of AAC training which professionals in England must receive. Evidence suggests that AAC training for pre-qualification professionals is limited and this paper has identified variation in the amount and type of post-qualification AAC training. While knowledge concerning specific AAC systems is necessary, focussing training primarily on this area may not address critical gaps in knowledge. There is a need for specific recommendations regarding AAC training for professionals in this field, to ensure professionals can fully support people who use AAC

The in vivo assessment of thoracic vertebral shape from MRI data using a shape model

This is the author accepted manuscript. The final version is available from Elsevier via the DOI in this record.Study design Feasibility study on characterising thoracic vertebral shape from magnetic resonance images using a shape model. Objectives Assess the reliability of characterising thoracic vertebral shape from magnetic resonance images and estimate the normal variation in vertebral shape using a shape model. Summary of background data The characterisation of thoracic vertebrae shape is important for understanding the initiation and progression of deformity and in developing surgical methods. Methods for characterising shape need to be comprehensive, reliable and suitable for use in vivo. Methods Magnetic resonance images of the thoracic vertebrae were acquired from 20 adults. Repeat scans were acquired, after repositioning the participants, for T4, T8 and T12. Landmark points were placed around the vertebra on the images and used to create a shape model. The reliability was assessed using relative error (E%) and intra-class correlation (ICC). The effect of vertebral level, sex and age on vertebral shape was assessed using repeated measures analysis of variance. Results Five modes of variation were retained from the shape model. Reliability was excellent for the first two modes (mode 1: E% = 7, ICC = 0.98; mode 2: E% = 11, ICC = 0.96). These modes described variation in the vertebral bodies, the pedicle width and orientation, and the facet joint position and orientation with respect to the pedicle axis. Variation in vertebral shape was found along the thoracic spine and between individuals, but there was little effect of age and sex. Conclusions Magnetic resonance images and shape modelling provides a reliable method for characterising vertebral shape in vivo. The method is able to identify differences between vertebral levels and between individuals. The use of these methods may be advantageous for performing repeated measurements in longitudinal studies

The academic radiography workforce: Age profile, succession planning and academic development.

This is the author accepted manuscript. The final version is available from Elsevier via the DOI in this record.Introduction: Academia is one area of practice in which radiographers can specialise; they compile approximately 2% of the total radiography profession in the UK, but are highly influential and essential for the education and development of the workforce in addition to undertaking research. However, the academic environment is very different to clinical practice and a period of transition is required. Methods: Data were collated to explore the age and retirement profile of the academic radiography workforce in the UK; to understand the research time allocated to this workforce; the time required to develop a clinical radiographer into an academic and the mentorship and succession planning provisions nationally. An online UK wide survey was conducted and sent to all 24 Universities delivering radiography education within the UK. Results: Eighteen out of 24 Universities in the UK responded to the survey. Approximately 30% of radiography academics are due to retire over the next ten years, with over 25% of radiographers who currently hold a doctorate qualification included within this figure. Those entering academia have notably lower qualifications as a group than those who are due to retire. Developing clinical radiographers into academics was thought to take 1-3 years on average, or longer if they are required to undertake research. Conclusion: There is vulnerability in the academic radiography workforce. Higher education institutions need to invest in developing the academic workforce to maintain research and educational expertise, which is underpinned by master’s and doctorate level qualifications

Lithium Intercalation into the Excitonic Insulator Candidate Ta2NiSe5

A new reduced phase derived from the excitonic insulator candidate Ta2NiSe5 has been synthesized via the intercalation of lithium. LiTa2NiSe5 crystallizes in the orthorhombic space group Pmnb (no. 62) with lattice parameters a = 3.50247(3) Å, b = 13.4053(4) Å, c = 15.7396(2) Å, and Z = 4, with an increase of the unit cell volume by 5.44(1)% compared with Ta2NiSe5. Significant rearrangement of the Ta-Ni-Se layers is observed, in particular a very significant relative displacement of the layers compared to the parent phase, similar to that which occurs under hydrostatic pressure. Neutron powder diffraction experiments and computational analysis confirm that Li occupies a distorted triangular prismatic site formed by Se atoms of adjacent Ta2NiSe5 layers with an average Li-Se bond length of 2.724(2) Å. Li-NMR experiments show a single Li environment at ambient temperature. Intercalation suppresses the distortion to monoclinic symmetry that occurs in Ta2NiSe5 at 328 K and that is believed to be driven by the formation of an excitonic insulating state. Magnetometry data show that the reduced phase has a smaller net diamagnetic susceptibility than Ta2NiSe5 due to the enhancement of the temperature-independent Pauli paramagnetism caused by the increased density of states at the Fermi level evident also from the calculations, consistent with the injection of electrons during intercalation and formation of a metallic phase

The crystalline structure of the phenazine overlayer physisorbed on a graphite surface

The monolayer crystal structure of phenazine adsorbed on graphite is determined by a combination of synchrotron X-ray diffraction and DFT calculations. The molecules adopt a rectangular unit cell with lattice parameters a = 13.55 Å and b = 10.55 Å, which contains 2 molecules. The plane group of the unit cell is p2gg, and each molecule is essentially flat to the plane of the surface, with only a small amount of out-of-plane tilt. Density Functional Theory (DFT) calculations find a minimum energy structure with a unit cell which agrees within 7.5% with that deduced by diffraction. DFT including dispersion force corrections (DFT+D) calculations help to identify the nature of the intermolecular bonding. The overlayer interactions are principally van der Waals, with a smaller contribution from weak C-H•••N hydrogen bonds. This behaviour is compared with that of 4,4’-bipyridyl.We acknowledge financial support for AB from an EPSRC DTA award from the Department of Chemistry, University of Cambridge; and BP for financial support for CT. We thank Diamond Light Source for access to beamline I11 (EE7761) that contributed to the results presented here. The DFT calculations were performed using the Darwin Supercomputer of the University of Cambridge High Performance Computing Service.This is the accepted manuscript. The final version is available from Taylor & Francis at http://www.tandfonline.com/doi/abs/10.1080/00268976.2013.793844#.VGHd34XziEo

Survival of the fittest: Retrospective cohort study of the longevity of Olympic medallists in the modern era

Objective: To determine whether Olympic medallists live longer than the general population. Design: Retrospective cohort study, with passive follow-up and conditional survival analysis to account for unidentified loss to follow-up. Setting and participants: 15 174 Olympic athletes from nine country groups (United States, Germany, Nordic countries, Russia, United Kingdom, France, Italy, Canada, and Australia and New Zealand) who won medals in the Olympic Games held in 1896-2010. Medallists were compared with matched cohorts in the general population (by country, age, sex, and year of birth). Main outcome measures Relative conditional survival. Results: More medallists than matched controls in the general population were alive 30 years after winning (relative conditional survival 1.08, 95% confidence interval 1.07 to 1.10). Medallists lived an average of 2.8 years longer than controls. Medallists in eight of the nine country groups had a significant survival advantage compared with controls. Gold, silver, and bronze medallists each enjoyed similar sized survival advantages. Medallists in endurance sports and mixed sports had a larger survival advantage over controls at 30 years (1.13, 1.09 to 1.17; 1.11, 1.09 to 1.13) than that of medallists in power sports (1.05, 1.01 to 1.08). Conclusions: Olympic medallists live longer than the general population, irrespective of country, medal, or sport. This study was not designed to explain this effect, but possible explanations include genetic factors, physical activity, healthy lifestyle, and the wealth and status that come with international sporting glory. © BMJ Publishing Group Ltd 2012