Realistic Ionizing Fluxes for Young Stellar Populations from 0.05 to twice solar metallicity

We present a new grid of ionizing fluxes for O and Wolf-Rayet stars for use with evolutionary synthesis codes and single star H II region analyses. A total of 230 expanding, non-LTE, line-blanketed model atmospheres have been calculated for five metallicities (0.05, 0.2, 0.4, 1 and 2 solar) using the WM-basic code of Pauldrach et al. (2001) and the CMFGEN code of Hillier & Miller (1998). The stellar wind parameters are scaled with metallicity for both O and W-R stars. We incorporate the new models into Starburst99 (Leitherer et al. 1999) and compare the ionizing outputs with Schaerer & Vacca (1998) and Leitherer et al. (1999). The changes in the output ionizing fluxes are dramatic, particularly below 228 A. We also find lower fluxes in the He I continuum for Z > 0.4 solar and ages < 7 Myr because of the increased line blanketing. We test the accuracy of the new models by constructing photoionization models. We show that for the dwarf O star grid, He I 5876/H beta decreases between Z = 1 and twice solar in a similar manner to observations (e.g. Bresolin et al. 1999) due to the increased effect of line blanketing. We therefore suggest that a lowering of the upper mass limit at high abundances is not required to explain the observations. For the case of an instantaneous burst, we plot the softness parameter "eta prime" against the abundance indicator R_23. The new models are coincident with the data of Bresolin et al. (1999), particularly during the W-R phase, unlike previous models which over-predict the hardness of the ionizing radiation.Comment: 21 pages, 15 postscript colour figures, includes mn2e.cls. To be published in MNRAS. Revised version containing modifications to Tables 1-

Probing the Rotational Velocity of Galactic WO Stars with Spectropolarimetry

Oxygen sequence Wolf-Rayet stars (WO) are thought to be the final evolution phase of some high-mass stars, as such they may be the progenitors of Type Ic SNe as well as potential progenitors of broad-lined Ic and long gamma-ray bursts. We present the first spectropolarimetric observations of the Galactic WO stars WR93b and WR102 obtained with FORS1 on the Very Large Telescope. We find no sign of a line effect, which could be expected if these stars were rapid rotators. We also place constraints on the amplitude of a potentially undetected line effect. This allows us to derive upper limits on the possible intrinsic continuum polarization and find Pcont \u3c 0.077 per cent and Pcont \u3c 0.057 per cent for WR93b and WR102, respectively. Furthermore, we derive upper limits on the rotation of our WO stars by considering our results in the context of the wind compression effect. We estimate that for an edge-on case the rotational velocity of WR93b is vrot \u3c 324 km s−1 while for WR102 vrot \u3c 234 km s−1. These correspond to values of vrot/vcrit \u3c 19 per cent and j) \u3c 18.0 cm2 s−1 for WR93b and 2 s−1 for WR102. The upper limits found on vrot/vcrit and log(j) for our WO stars are therefore similar to the estimates calculated for Galactic Wolf-Rayet (WR) stars that do show a line effect. Therefore, although the presence of a line effect in a single WR star is indicative of fast rotation, the absence of a line effect does not rule out significant rotation, even when considering the edge-on scenario

A Neutron Star with a Massive Progenitor in Westerlund 1

We report the discovery of an X-ray pulsar in the young, massive Galactic star cluster Westerlund 1. We detected a coherent signal from the brightest X-ray source in the cluster, CXO J164710.2-455216, during two Chandra observations on 2005 May 22 and June 18. The period of the pulsar is 10.6107(1) s. We place an upper limit to the period derivative of Pdot<2e-10 s/s, which implies that the spin-down luminosity is Edot<3e33 erg/s. The X-ray luminosity of the pulsar is L_X = 3(+10,-2)e33 (D/5 kpc)^2 erg/s, and the spectrum can be described by a kT = 0.61+/-0.02 keV blackbody with a radius of R_bb = 0.27+/-0.03 (D/5 kpc}) km. Deep infrared observations reveal no counterpart with K1 Msun. Taken together, the properties of the pulsar indicate that it is a magnetar. The rarity of slow X-ray pulsars and the position of CXO J164710.2-455216 only 1.6' from the core of Westerlund 1 indicates that it is a member of the cluster with >99.97% confidence. Westerlund 1 contains 07V stars with initial masses M_i=35 Msun and >50 post-main-sequence stars that indicate the cluster is 4+/-1 Myr old. Therefore, the progenitor to this pulsar had an initial mass M_i>40 Msun. This is the most secure result among a handful of observational limits to the masses of the progenitors to neutron stars.Comment: 4 pages, 5 figures. Final version to match ApJL (added one figure since v2

Sequence-based prediction for vaccine strain selection and identification of antigenic variability in foot-and-mouth disease virus

Identifying when past exposure to an infectious disease will protect against newly emerging strains is central to understanding the spread and the severity of epidemics, but the prediction of viral cross-protection remains an important unsolved problem. For foot-and-mouth disease virus (FMDV) research in particular, improved methods for predicting this cross-protection are critical for predicting the severity of outbreaks within endemic settings where multiple serotypes and subtypes commonly co-circulate, as well as for deciding whether appropriate vaccine(s) exist and how much they could mitigate the effects of any outbreak. To identify antigenic relationships and their predictors, we used linear mixed effects models to account for variation in pairwise cross-neutralization titres using only viral sequences and structural data. We identified those substitutions in surface-exposed structural proteins that are correlates of loss of cross-reactivity. These allowed prediction of both the best vaccine match for any single virus and the breadth of coverage of new vaccine candidates from their capsid sequences as effectively as or better than serology. Sub-sequences chosen by the model-building process all contained sites that are known epitopes on other serotypes. Furthermore, for the SAT1 serotype, for which epitopes have never previously been identified, we provide strong evidence - by controlling for phylogenetic structure - for the presence of three epitopes across a panel of viruses and quantify the relative significance of some individual residues in determining cross-neutralization. Identifying and quantifying the importance of sites that predict viral strain cross-reactivity not just for single viruses but across entire serotypes can help in the design of vaccines with better targeting and broader coverage. These techniques can be generalized to any infectious agents where cross-reactivity assays have been carried out. As the parameterization uses pre-existing datasets, this approach quickly and cheaply increases both our understanding of antigenic relationships and our power to control disease

Length of carotid stenosis predicts peri-procedural stroke or death and restenosis in patients randomized to endovascular treatment or endarterectomy.

BACKGROUND: The anatomy of carotid stenosis may influence the outcome of endovascular treatment or carotid endarterectomy. Whether anatomy favors one treatment over the other in terms of safety or efficacy has not been investigated in randomized trials. METHODS: In 414 patients with mostly symptomatic carotid stenosis randomized to endovascular treatment (angioplasty or stenting; n = 213) or carotid endarterectomy (n = 211) in the Carotid and Vertebral Artery Transluminal Angioplasty Study (CAVATAS), the degree and length of stenosis and plaque surface irregularity were assessed on baseline intraarterial angiography. Outcome measures were stroke or death occurring between randomization and 30 days after treatment, and ipsilateral stroke and restenosis ≥50% during follow-up. RESULTS: Carotid stenosis longer than 0.65 times the common carotid artery diameter was associated with increased risk of peri-procedural stroke or death after both endovascular treatment [odds ratio 2.79 (1.17-6.65), P = 0.02] and carotid endarterectomy [2.43 (1.03-5.73), P = 0.04], and with increased long-term risk of restenosis in endovascular treatment [hazard ratio 1.68 (1.12-2.53), P = 0.01]. The excess in restenosis after endovascular treatment compared with carotid endarterectomy was significantly greater in patients with long stenosis than with short stenosis at baseline (interaction P = 0.003). Results remained significant after multivariate adjustment. No associations were found for degree of stenosis and plaque surface. CONCLUSIONS: Increasing stenosis length is an independent risk factor for peri-procedural stroke or death in endovascular treatment and carotid endarterectomy, without favoring one treatment over the other. However, the excess restenosis rate after endovascular treatment compared with carotid endarterectomy increases with longer stenosis at baseline. Stenosis length merits further investigation in carotid revascularisation trials

No Plan B: the Achilles heel of high performance sport management

Research question: The severity and immediacy of funding cuts to UK National Governing Bodies of Sport (NGBs), driven by the ‘No Compromise’ policy framework for Olympic funding, triggers a cyclical need for turnaround management. Adept strategies during times of considerable challenge is stark, yet literature investigating turnaround management within NGBs remains limited. Consequently, this paper examines two questions: how do NGBs respond to UK Sport funding cuts and how are their responses enabled or restricted by their organisational context? Research methods: A case study methodology was used to develop in-depth insights into how three NGBs responded over a twelve-month period of turnaround management. This was informed by 21 semi-structured interviews with chief executives/presidents, performance managers/head coaches and elite athletes. The actions of the NGBs were analysed through a thematic analysis that made use of Boyne’s (2004) 3 Rs of turnaround strategy. Results and findings: The results highlight that NGBs’ turnaround strategies were constrained by extreme funding dependency and a prohibitive institutional environment that led to states of flux and a focus on short-term operational survival. As a result, the measures taken undermined future success. Implications: An embedded feature of the ‘No Compromise’ framework is severe funding cuts. This should be a significant theme in NGB strategy development. The evidence of this study is that NGBs do not prepare, nor react strategically, when faced with the prospect (or fact of) severe cuts. Consequently, the cases of turnaround management in this study signal the urgent need for further research into the impact of the ‘No Compromise’ framework on the management of NGBs

Poor glycaemic control is associated with reduced exercise performance and oxygen economy during cardio-pulmonary exercise testing in people with type 1 diabetes

BackgroundTo explore the impact of glycaemic control (HbA1c) on functional capacity during cardio-pulmonary exercise testing in people with type 1 diabetes.MethodsSixty-four individuals with type 1 diabetes (age: 34 ± 8 years; 13 females, HbA1c: 7.8 ± 1% (62 ± 13 mmol/mol), duration of diabetes: 17 ± 9 years) performed a cardio-pulmonary cycle ergometer exercise test until volitional exhaustion. Stepwise linear regression was used to explore relationships between HbA1c and cardio-respiratory data with p ≤ 0.05. Furthermore, participants were divided into quartiles based on HbA1c levels and cardio-respiratory data were analysed by one-way ANOVA. Multiple regression analysis was performed to explore the relationships between changes in time to exhaustion and cardio-respiratory data. Data were adjusted for confounder.ResultsHbA1c was related to time to exhaustion and oxygen consumption at the power output elicited at the sub-maximal threshold of the heart rate turn point (r = 0.47, R2 = 0.22, p = 0.03). Significant differences were found at time to exhaustion between QI vs. QIV and at oxygen consumption at the power output elicited at the heart rate turn point between QI vs. QII and QI vs. QIV (p < 0.05). Changes in oxygen uptake, power output and in oxygen consumption at the power output elicited at the heart rate turn point and at maximum power output explained 55% of the variance in time to exhaustion (r = 0.74, R2 = 0.55, p < 0.01).ConclusionsPoor glycaemic control is related to less economical use of oxygen at sub-maximal work rates and an earlier time to exhaustion during cardio-pulmonary exercise testing. However, exercise training could have the same potential to counteract the influence of poor glycaemic control on functional capacity

Increasing walking in patients with intermittent claudication: Protocol for a randomised controlled trial

Background: People with intermittent claudication are at increased risk of death from heart attack and stroke compared to matched controls. Surgery for intermittent claudication is for symptom management and does not reduce the risk of cardiovascular morbidity and mortality. Increasing physical activity can reduce claudication symptoms and may improve cardiovascular health. This paper presents the pilot study protocol for a randomised controlled trial to test whether a brief psychological intervention leads to increased physical activity, improvement in quality of life, and a reduction in the demand for surgery, for patients with intermittent claudication. Methods/Design: We aim to recruit 60 patients newly diagnosed with intermittent claudication, who will be randomised into two groups. The control group will receive usual care, and the treatment group will receive usual care and a brief 2-session psychological intervention to modify illness and walking beliefs and develop a walking action plan. The primary outcome will be walking, measured by pedometer. Secondary outcomes will include quality of life and uptake of surgery for symptom management. Participants will be followed up after (a) 4 months, (b) 1 year and (c) 2 years. Discussion: This study will assess the acceptability and efficacy of a brief psychological intervention to increase walking in patients with intermittent claudication, both in terms of the initiation, and maintenance of behaviour change. This is a pilot study, and the results will inform the design of a larger multi-centre trial. Trial Registration: Current Controlled Trials ISRCTN2805187