Probing Wolf-Rayet Winds: Chandra/HETG X-Ray Spectra of WR 6

With a deep Chandra/HETGS exposure of WR 6, we have resolved emission lines whose profiles show that the X-rays originate from a uniformly expanding spherical wind of high X-ray-continuum optical depth. The presence of strong helium-like forbidden lines places the source of X-ray emission at tens to hundreds of stellar radii from the photosphere. Variability was present in X-rays and simultaneous optical photometry, but neither were correlated with the known period of the system or with each other. An enhanced abundance of sodium revealed nuclear processed material, a quantity related to the evolutionary state of the star. The characterization of the extent and nature of the hot plasma in WR 6 will help to pave the way to a more fundamental theoretical understanding of the winds and evolution of massive stars.Comment: Accepted by the Astrophysical Journa

The SMC SNR 1E0102.2-7219 as a Calibration Standard for X-ray Astronomy in the 0.3-2.5 keV Bandpass

The flight calibration of the spectral response of CCD instruments below 1.5 keV is difficult in general because of the lack of strong lines in the on-board calibration sources typically available. We have been using 1E 0102.2-7219, the brightest supernova remnant in the Small Magellanic Cloud, to evaluate the response models of the ACIS CCDs on the Chandra X-ray Observatory (CXO), the EPIC CCDs on the XMM-Newton Observatory, the XIS CCDs on the Suzaku Observatory, and the XRT CCD on the Swift Observatory. E0102 has strong lines of O, Ne, and Mg below 1.5 keV and little or no Fe emission to complicate the spectrum. The spectrum of E0102 has been well characterized using high-resolution grating instruments, namely the XMM-Newton RGS and the CXO HETG, through which a consistent spectral model has been developed that can then be used to fit the lower-resolution CCD spectra. We have also used the measured intensities of the lines to investigate the consistency of the effective area models for the various instruments around the bright O (~570 eV and 654 eV) and Ne (~910 eV and 1022 eV) lines. We find that the measured fluxes of the O VII triplet, the O VIII Ly-alpha line, the Ne IX triplet, and the Ne X Ly-alpha line generally agree to within +/-10 % for all instruments, with 28 of our 32 fitted normalizations within +/-10% of the RGS-determined value. The maximum discrepancies, computed as the percentage difference between the lowest and highest normalization for any instrument pair, are 23% for the O VII triplet, 24% for the O VIII Ly-alpha line, 13% for the Ne IX triplet, and 19% for the Ne X Ly-alpha line. If only the CXO and XMM are compared, the maximum discrepancies are 22% for the O VII triplet, 16% for the O VIII Ly-alpha line, 4% for the Ne IX triplet, and 12% for the Ne X Ly-alpha line.Comment: 16 pages, 11 figures, to be published in Proceedings of the SPIE 7011: Space Telescopes and Instrumentation II: Ultraviolet to Gamma Ray 200

A model of tuberculosis clustering in low incidence countries reveals more transmission in the United Kingdom than the Netherlands between 2010 and 2015

Tuberculosis (TB) remains a public health threat in low TB incidence countries, through a combination of reactivated disease and onward transmission. Using surveillance data from the United Kingdom (UK) and the Netherlands (NL), we demonstrate a simple and predictable relationship between the probability of observing a cluster and its size (the number of cases with a single genotype). We demonstrate that the full range of observed cluster sizes can be described using a modified branching process model with the individual reproduction number following a Poisson lognormal distribution. We estimate that, on average, between 2010 and 2015, a TB case generated 0.41 (95% CrI 0.30,0.60) secondary cases in the UK, and 0.24 (0.14,0.48) secondary cases in the NL. A majority of cases did not generate any secondary cases. Recent transmission accounted for 39% (26%,60%) of UK cases and 23%(13%,37%) of NL cases. We predict that reducing UK transmission rates to those observed in the NL would result in 538(266,818) fewer cases annually in the UK. In conclusion, while TB in low incidence countries is strongly associated with reactivated infections, we demonstrate that recent transmission remains sufficient to warrant policies aimed at limiting local TB spread

SNR 1E 0102.2-7219 as an X-ray calibration standard in the 0.5−1.0 keV bandpass and its application to the CCD instruments aboard Chandra , Suzaku , Swift and XMM-Newton

Context. The flight calibration of the spectral response of charge-coupled device (CCD) instruments below 1.5 keV is difficult in general because of the lack of strong lines in the on-board calibration sources typically available. This calibration is also a function of time due to the effects of radiation damage on the CCDs and/or the accumulation of a contamination layer on the filters or CCDs. Aims. We desire a simple comparison of the absolute effective areas of the current generation of CCD instruments onboard the following observatories: Chandra ACIS-S3, XMM-Newton (EPIC-MOS and EPIC-pn), Suzaku XIS, and Swift XRT and a straightforward comparison of the time-dependent response of these instruments across their respective mission lifetimes. Methods. We have been using 1E 0102.2-7219, the brightest supernova remnant in the Small Magellanic Cloud, to evaluate and modify the response models of these instruments. 1E 0102.2-7219 has strong lines of O, Ne, and Mg below 1.5 keV and little or no Fe emission to complicate the spectrum. The spectrum of 1E 0102.2-7219 has been well-characterized using the RGS gratings instrument on XMM-Newton and the HETG gratings instrument on Chandra. As part of the activities of the International Astronomical Consortium for High Energy Calibration (IACHEC), we have developed a standard spectral model for 1E 0102.2-7219 and fit this model to the spectra extracted from the CCD instruments. The model is empirical in that it includes Gaussians for the identified lines, an absorption component in the Galaxy, another absorption component in the SMC, and two thermal continuum components with different temperatures. In our fits, the model is highly constrained in that only the normalizations of the four brightest lines/line complexes (the O vii Heα triplet, O viii Lyα line, the Ne ix Heα triplet, and the Ne x Lyα line) and an overall normalization are allowed to vary, while all other components are fixed. We adopted this approach to provide a straightforward comparison of the measured line fluxes at these four energies. We have examined these measured line fluxes as a function of time for each instrument after applying the most recent calibrations that account for the time-dependent response of each instrument. Results. We performed our effective area comparison with representative, early mission data when the radiation damage and contamination layers were at a minimum, except for the XMM-Newton EPIC-pn instrument which is stable in time. We found that the measured fluxes of the O vii Heαr line, the O viii Lyα line, the Ne ix Heαr line, and the Ne x Lyα line generally agree to within ±10% for all instruments, with 38 of our 48 fitted normalizations within ± 10% of the IACHEC model value. We then fit all available observations of 1E 0102.2-7219 for the CCD instruments close to the on-axis position to characterize the time dependence in the 0.5−1.0 keV band. We present the measured line normalizations as a function of time for each CCD instrument so that the users may estimate the uncertainty in their measured line fluxes for the epoch of their observations

Utilisation of an operative difficulty grading scale for laparoscopic cholecystectomy

Background A reliable system for grading operative difficulty of laparoscopic cholecystectomy would standardise description of findings and reporting of outcomes. The aim of this study was to validate a difficulty grading system (Nassar scale), testing its applicability and consistency in two large prospective datasets. Methods Patient and disease-related variables and 30-day outcomes were identified in two prospective cholecystectomy databases: the multi-centre prospective cohort of 8820 patients from the recent CholeS Study and the single-surgeon series containing 4089 patients. Operative data and patient outcomes were correlated with Nassar operative difficultly scale, using Kendall’s tau for dichotomous variables, or Jonckheere–Terpstra tests for continuous variables. A ROC curve analysis was performed, to quantify the predictive accuracy of the scale for each outcome, with continuous outcomes dichotomised, prior to analysis. Results A higher operative difficulty grade was consistently associated with worse outcomes for the patients in both the reference and CholeS cohorts. The median length of stay increased from 0 to 4 days, and the 30-day complication rate from 7.6 to 24.4% as the difficulty grade increased from 1 to 4/5 (both p < 0.001). In the CholeS cohort, a higher difficulty grade was found to be most strongly associated with conversion to open and 30-day mortality (AUROC = 0.903, 0.822, respectively). On multivariable analysis, the Nassar operative difficultly scale was found to be a significant independent predictor of operative duration, conversion to open surgery, 30-day complications and 30-day reintervention (all p < 0.001). Conclusion We have shown that an operative difficulty scale can standardise the description of operative findings by multiple grades of surgeons to facilitate audit, training assessment and research. It provides a tool for reporting operative findings, disease severity and technical difficulty and can be utilised in future research to reliably compare outcomes according to case mix and intra-operative difficulty

Erratum to:Effects of a physical activity and nutrition program in retirement villages: a cluster randomised controlled trial

Abstract Background This cluster randomised controlled trial aimed to determine if a 6- month home-based intervention could improve the physical activity and dietary behaviours of adults aged 60 to 80 years living in retirement villages located in Perth, Western Australia. Methods Participants (n = 363) from 38 retirement villages were recruited into the trial and allocated to the intervention (n = 197: 17 sites) or control (n = 166: 21 sites) group and were blinded. Previously validated instruments-Fat and Fibre Barometer and International Physical Activity Questionnaire, along with anthropometric measures (weight, height, waist and hip circumferences) and blood pressure were collected at baseline and 6 -month time period. Comparisons between intervention and control groups were undertaken pre- and post- intervention using univariate chi-square and t-tests. Multi-level mixed regression analyses were then conducted to ascertain the effects of the intervention on changes in the outcome variables over time and between groups. Results A total of 139 (70.5%) intervention and 141 (84.9%) control group participants completed the program and post-test assessments. The intervention group demonstrated significant increases in time (80 min more per week on average) devoted to moderate-intensity physical activity, engagement in strength exercises (from 23.7% to 48.2%), frequency of fruit consumed as well as fat avoidance and fibre intake scores, in addition to a 0.5 kg mean reduction in weight post program, whereas no apparent changes were observed in the control group. Mixed regression results further confirmed statistically significant improvements in weight loss (p < 0.05), engagement in strength exercises (p < 0.001) and fruit intake (p = 0.012) by the intervention participants at post-test relative to their controls. Conclusions Retirement offers a time to reassess lifestyle, and adopt positive health enhancing physical activity and dietary behaviours. This intervention was successful in improving weight, engagement in strength exercises, increasing levels of moderate-intensity physical activity and consumption of fruit among retirement village residents. Further investigation is needed on how to better engage retirement village managers in such programs. Trial registration Australia and New Zealand Clinical Trial Registry (ACTRN12612001168842) registered November 2, 2012

Oral abstracts 1: SpondyloarthropathiesO1. Detecting axial spondyloarthritis amongst primary care back pain referrals

Background: Inflammatory back pain (IBP) is an early feature of ankylosing spondylitis (AS) and its detection offers the prospect of early diagnosis of AS. However, since back pain is very common but only a very small minority of back pain sufferers have ASpA or AS, screening of back pain sufferers for AS is problematic. In early disease radiographs are often normal so that fulfilment of diagnostic criteria for AS is impossible though a diagnosis of axial SpA can be made if MRI evidence of sacroiliitis is present. This pilot study was designed to indicate whether a cost-effective pick up rate for ASpA/early AS could be achieved by identifying adults with IBP stratified on the basis of age. Methods: Patients aged between 18 and 45 years who were referred to a hospital physiotherapy service with back pain of more than 3 months duration were assessed for IBP. All were asked to complete a questionnaire based on the Berlin IBP criteria. Those who fulfilled IBP criteria were also asked to complete a second short questionnaire enquiring about SpA comorbidities, to have a blood test for HLA-B27 and CRP level and to undergo an MRI scan of the sacroiliac joints. This was a limited scan, using STIR, diffusion-weighted, T1 and T2 sequences of the sacroiliac joints to minimize time in the scanner and cost. The study was funded by a research grant from Abbott Laboratories Ltd. Results: 50 sequential patients agreed to participate in the study and completed the IBP questionnaire. Of these 27 (54%) fulfilled criteria for IBP. Of these, 2 patients reported a history of an SpA comorbidity - 1 psoriasis; 1 ulcerative colitis - and 3 reported a family history of an SpA comorbidity - 2 psoriasis; 1 Crohn's disease. 4 were HLA-B27 positive, though results were not available for 7. Two patients had marginally raised CRP levels (6, 10 -NR ≤ 5). 19 agreed to undergo MRI scanning of the sacroiliac joints and lumbar spine; 4 scans were abnormal, showing evidence of bilateral sacroiliitis on STIR sequences. In all cases the changes met ASAS criteria but were limited. Of these 4 patients 3 were HLA-B27 positive but none gave a personal or family history of an SpA-associated comorbidity and all had normal CRP levels. Conclusions: This was a pilot study yielding only limited conclusions. However, it is clear that: Screening of patients referred for physiotherapy for IBP is straightforward, inexpensive and quick. It appears that IBP is more prevalent in young adults than overall population data suggest so that targeting this population may be efficient. IBP questionnaires could be administered routinely during a physiotherapy assessment. HLA-B27 testing in this group of patients with IBP is a suitable screening tool. The sacroiliac joint changes identified were mild and their prognostic significance is not yet clear so that the value of early screening needs further evaluation. Disclosure statement: C.H. received research funding for this study from Abbott. A.K. received research funding for this study, and speaker and consultancy fees, from Abbott. All other authors have declared no conflicts of interes