Numerical Simulations of Optically Thick Accretion onto a Black Hole - I. Spherical Case

Modeling the radiation generated by accreting matter is an important step towards realistic simulations of black hole accretion disks, especially at high accretion rates. To this end, we have recently added radiation transport to the existing general relativistic magnetohydrodynamic code, Cosmos++. However, before attempting to model radiative accretion disks, we have tested the new code using a series of shock tube and Bondi (spherical inflow) problems. The four radiative shock tube tests, first presented by Farris et al. (2008), have known analytic solutions, allowing us to calculate errors and convergence rates for our code. The Bondi problem only has an analytic solution when radiative processes are ignored, but is pertinent because it is closer to the physics we ultimately want to study. In our simulations, we include Thomson scattering and thermal bremsstrahlung in the opacity, focusing exclusively on the super-Eddington regime. Unlike accretion onto bodies with solid surfaces, super-Eddington accretion onto black holes does not produce super-Eddington luminosity. In our examples, despite accreting at up to 300 times the Eddington rate, our measured luminosity is always several orders of magnitude below Eddington.Comment: 15 pages, 6 figures, ApJS accepted versio

The use of randomisation-based efficacy estimators in non-inferiority trials

Background In a non-inferiority (NI) trial, analysis based on the intention-to-treat (ITT) principle is anti-conservative, so current guidelines recommend analysing on a per-protocol (PP) population in addition. However, PP analysis relies on the often implausible assumption of no confounders. Randomisation-based efficacy estimators (RBEEs) allow for treatment non-adherence while maintaining a comparison of randomised groups. Fischer et al. have developed an approach for estimating RBEEs in randomised trials with two active treatments, a common feature of NI trials. The aim of this paper was to demonstrate the use of RBEEs in NI trials using this approach, and to appraise the feasibility of these estimators as the primary analysis in NI trials. Methods Two NI trials were used. One comparing two different dosing regimens for the maintenance of remission in people with ulcerative colitis (CODA), and the other comparing an orally administered treatment to an intravenously administered treatment in preventing skeletal-related events in patients with bone metastases from breast cancer (ZICE). Variables that predicted adherence in each of the trial arms, and were also independent of outcome, were sought in each of the studies. Structural mean models (SMMs) were fitted that conditioned on these variables, and the point estimates and confidence intervals compared to that found in the corresponding ITT and PP analyses. Results In the CODA study, no variables were found that differentially predicted treatment adherence while remaining independent of outcome. The SMM, using standard methodology, moved the point estimate closer to 0 (no difference between arms) compared to the ITT and PP analyses, but the confidence interval was still within the NI margin, indicating that the conclusions drawn would remain the same. In the ZICE study, cognitive functioning as measured by the corresponding domain of the QLQ-C30, and use of chemotherapy at baseline were both differentially associated with adherence while remaining independent of outcome. However, while the SMM again moved the point estimate closer to 0, the confidence interval was wide, overlapping with any NI margin that could be justified. Conclusion Deriving RBEEs in NI trials with two active treatments can provide a randomisation-respecting estimate of treatment efficacy that accounts for treatment adherence, is straightforward to implement, but requires thorough planning during the design stage of the study to ensure that strong baseline predictors of treatment are captured. Extension of the approach to handle nonlinear outcome variables is also required. Trial registration The CODA study: ClinicalTrials.gov, identifier: NCT00708656. Registered on 8 April 2008. The ZICE study trial: ClinicalTrials.gov, identifier: NCT00326820. Registered on 16 May 2006

The quality of English-language websites offering falls-prevention advice to older members of the public and their families

Falls among older people are a major public health issue. Increasing numbers of older people are accessing the internet for health-related information, including information on falls risk and prevention. However, we are aware of no study that has assessed the quality of such websites. Using techniques for conducting systematic literature reviews, we evaluated English-language websites offering falls-related advice to members of the public. Forty-two websites were identified using popular search engines; these were assessed using evidence-based guidelines and codes of conduct on coverage of falls-related information, credibility and senior friendliness. Overall, scores were poor for coverage of falls information and credibility, although they were higher for senior friendliness. Few of the websites had been recently updated and none provided individually-tailored advice. We conclude that websites have fallen short of their potential to provide accessible, evidence-based information on the risks of falls and their prevention. © The Author(s) 2012

Structural and Functional Lung Impairment in Adult Survivors of Bronchopulmonary Dysplasia

RATIONALE: As more preterm infants recover from severe bronchopulmonary dysplasia (BPD), it is critical to understand the clinical consequences of this condition on the lung health of adult survivors.OBJECTIVES: To assess structural and functional lung parameters in young adult BPD survivors and preterm and term controls Methods: Young adult survivors of BPD (mean age 24) underwent spirometry, lung volumes, transfer factor, lung clearance index and fractional exhaled nitric oxide measurements together with high-resolution chest tomographic (CT) imaging and cardiopulmonary exercise testing.MEASUREMENTS AND MAIN RESULTS: 25 adult BPD survivors, (mean ± SD gestational age 26.8 ± 2.3 weeks; birth weight 866 ± 255 g), 24 adult prematurely born non-BPD controls (gestational age 30.6 ± 1.9 weeks; birth weight 1234 ± 207 g) and 25 adult term birth control subjects (gestational age 38.5 ± 0.9 weeks; and birth weight 3569 ± 2979 g) were studied. BPD subjects were more likely to be wakened by cough (OR 9.7, 95% CI: 1.8 to 52.6), p&lt;0.01), wheeze and breathlessness (OR 12.2, 95%CI: 1.3 to 112), p&lt;0.05) than term controls after adjusting for sex and current smoking. Preterm subjects had greater airways obstruction than term subjects. BPD subjects had significantly lower values for FEV1 and FEF25-75 (% predicted and z scores) than term controls (both p&lt;0.001). Although non-BPD subjects also had lower spirometric values than term controls, none of the differences reached statistical significance. More BPD subjects (25%) had fixed airflow obstruction than non-BPD (12.5%) and term (0%) subjects (p=0.004). Both BPD and non-BPD subjects had significantly greater impairment in gas transfer (KCO % predicted) than term subjects (both p&lt;0.05). Eighteen (37%) preterm participants were classified as small for gestational age (birth weight &lt; 10th percentile for gestational age). These subjects had significantly greater impairment in FEV1 (% predicted and z scores) than those born appropriate for gestational age. BPD survivors had significantly more severe radiographic structural lung impairment than non-BPD subjects. Both preterm groups had impaired exercise capacity compared to term controls. There was a trend for greater limitation and leg discomfort in BPD survivors.CONCLUSIONS: Adult preterm birth survivors, especially those who developed BPD, continue to experience respiratory symptoms and exhibit clinically important levels of pulmonary impairment.</p

Modelling the Dynamics of an Aedes albopictus Population

We present a methodology for modelling population dynamics with formal means of computer science. This allows unambiguous description of systems and application of analysis tools such as simulators and model checkers. In particular, the dynamics of a population of Aedes albopictus (a species of mosquito) and its modelling with the Stochastic Calculus of Looping Sequences (Stochastic CLS) are considered. The use of Stochastic CLS to model population dynamics requires an extension which allows environmental events (such as changes in the temperature and rainfalls) to be taken into account. A simulator for the constructed model is developed via translation into the specification language Maude, and used to compare the dynamics obtained from the model with real data.Comment: In Proceedings AMCA-POP 2010, arXiv:1008.314

permanence, discreteness and comprehensiveness

Most images do not appear."December 2013.""A Thesis Presented to the Faculty of the Graduate School at the University of Missouri--Columbia In Partial Fulfillment of the Requirements for the Degree Master of Fine Arts."Thesis supervisor: Professor J Brett Grill.Seeing-machines have long been used to discover new things about ourselves. We fantasize about devices that will enhance our senses and provide us with 'facts' about our hidden aspects, such as our inner bodies, or our psychology. But these viewing machines tend to obscure just as much as they reveal. By focusing vision they also constrain it and lose the context of that which is viewed. The search for the factual is so pervasive in society that it tends to be taken for granted by the sheer commonality of it. This diffusion of seeing-machines (some mechanical, some text-based) seeking out facts has necessitated my thesis calling upon a range of examples of how we use artificial systems to observe: x-rays, digital libraries, psychological tests etc. This broad approach was taken to emphasize the enormous popularity of mechanistic ways of seeing the world. My art project is a visual critique of the 'visual facts' provided by seeing machines, with a particular emphasis on technology's view of the body. The longevity, objectivity and comprehensiveness of artificial views of the physical body and psychology are scrutinized in my work. My images are created with a body scanner that creates degraded 'digital casts' of a posed model. This 'digital cast' is then lit virtually in a computer program before being printed on translucent paper and finally backlit in a display case. The result is a collection of images that depict ambiguous bodies that vacillate between recalcitrant materials and digital fragmentation. These images are housed in light boxes that resemble computer monitors and x-ray displays as a means of eliciting the technological gaze's view of the body.Includes bibliographical references (pages 71-76)

Natural variations in the biofilm-associated protein BslA from the genus <i>Bacillus</i>

AbstractBslA is a protein secreted by Bacillus subtilis which forms a hydrophobic film that coats the biofilm surface and renders it water-repellent. We have characterised three orthologues of BslA from Bacillus amyloliquefaciens, Bacillus licheniformis and Bacillus pumilus as well as a paralogue from B. subtilis called YweA. We find that the three orthologous proteins can substitute for BslA in B. subtilis and confer a degree of protection, whereas YweA cannot. The degree to which the proteins functionally substitute for native BslA correlates with their in vitro biophysical properties. Our results demonstrate the use of naturally-evolved variants to provide a framework for teasing out the molecular basis of interfacial self-assembly.</jats:p

Estimation of the spontaneous mutation rate in Heliconius melpomene

This is the final published version. It first appeared at mbe.oxfordjournals.org/content/early/2014/11/03/molbev.msu302.abstract.We estimated the spontaneous mutation rate in Heliconius melpomene by genome sequencing of\ud a pair of parents and 30 of their offspring, based on the ratio of number of de novo heterozygotes\ud to the number of callable site-individuals. We detected nine new mutations, each one affecting a\ud single site in a single offspring. This yields an estimated mutation rate of 2.9 x 10-9 (95%\ud confidence interval, 1.3 x 10-9 - 5.5 x 10-9), which is similar to recent estimates in Drosophila\ud melanogaster, the only other insect species in which the mutation rate has been directly estimated.\ud We infer that recent effective population size of H. melpomene is about 2 million, a substantially\ud lower value than its census size, suggesting a role for natural selection reducing diversity. We\ud estimate that H. melpomene diverged from its M?llerian co-mimic H. erato about 6 MYA, a\ud somewhat later date than estimates based on a local molecular clock.CJ was funded by BBSRC [H01439X/1], JWD was funded by the Herchel Smith Fund and PDK and\ud RWN were funded by the BBSRC