High-resolution spectroscopy of the R Coronae Borealis and Other Hydrogen Deficient Stars

High-resolution spectroscopy is a very important tool for studying stellar physics, perhaps, particularly so for such enigmatic objects like the R Coronae Borealis and related Hydrogen deficient stars that produce carbon dust in addition to their peculiar abundances. Examples of how high-resolution spectroscopy is used in the study of these stars to address the two major puzzles are presented: (i) How are such rare H-deficient stars created? and (ii) How and where are the obscuring soot clouds produced around the R Coronae Borealis stars?Comment: 16 pages, 9 figures, Astrophysics and Space Science Proceedings, Springer-Verlag, Berlin, 201

Baseline Severity as Predictor of Change in St George's Respiratory Questionnaire Scores in Trials of Long-acting Bronchodilators with COPD Patients.

Background: In trials oflong-acting bronchodilators, health status is an important trial outcome, however the influence of baseline severity on response measured by St George's Respiratory Questionnaire (SGRQ) is not known. We have compared SGRQ changes between patients with chronic obstructive pulmonary disease (COPD) of mild-moderate severity or dyspnea (Global initiative for chronic Obstructive Lung disease [GOLD] grades 1 and 2; modified Medical Research Council [mMRC] grades 1 and 2) to those with severe-very severe severity or dyspnea (GOLD grades 3 and 4; mMRC grades 3 and 4). Methods: Combined individual patient data from the COPD Biomarkers Qualification Consortium database (trials of long-acting bronchodilators) were used comprising of patients from short-term (≤1-year duration; n=10802) and medium-term (2-4 years' duration; n=8963) studies. A repeated measures analysis of variance (ANOVA) was used to determine the effects of baseline severity (GOLD/mMRC) on SGRQ response to treatment. All treatment arms were combined. Results: In short-term studies, milder patients showed a greater response than those with more severe disease in terms of GOLD grade (partial Eta(2) = 0.03, p < 0.0001) and mMRC grade (partial Eta(2) = 0.05, p < 0.0001). Similar results were seen in the medium-term studies (partial Eta(2) = 0.02, p < 0.0001; mMRC: partial Eta(2) = 0.05, p < 0.0001,). Conclusions: Patients with less severe airflow limitation and less severe dyspnea showed larger improvements in SGRQ score than more severely obstructed or dyspneic patients. Although these severity influences are small (2%-5% of the variance in SGRQ score), they do suggest that pre-specified separate analyses are warranted to test for differences in response, based on baseline severity

Responder Analyses for Treatment Effects in COPD Using the St George's Respiratory Questionnaire.

Background: Patient-reported outcomes data in clinical trials are usually reported as mean values, interpreted in comparison to a minimum clinically important difference (MCID) and ignoring the possibility of a sizable proportion of patients experiencing a worthwhile benefit when the majority did not. This analysis tested the reliability of calculated responder rates (from chronic obstructive pulmonary disease [COPD] patients) with the St George's Respiratory Questionnaire (SGRQ) using a range of responder cut-points above and below the MCID (4 units). Methods: Individual patient data (i.e., data from long-acting bronchodilator [LAB] and inhaled corticosteroids [ICS]/long-acting beta2-agonist [LABA] randomized clinical studies) in the COPD Biomarker Qualification Consortium database were used: short-term (≤1-year duration; 14,814 patients,) and medium-term (2-4 years; 12,043 patients). Responder rates versus placebo across SGRQ score change thresholds ranging from -1.5 to -8.0 were tested; differences were expressed as the odds ratio (OR) of a patient exceeding the threshold versus no change or deterioration. Results: The ORs measuring benefit of active treatment were similar across thresholds in short-term studies (LAB, ORs 1.40-1.42; LABA/ICS, 1.50-1.56) and medium-term LAB studies (ORs 1.34-1.43), whereas ORs in medium-term studies with LABA/ICS intervention showed a trend for higher response rates at higher values of threshold cut-points (1.64-1.79). In short-term studies, different thresholds had little effect on the OR between active drugs versus a trend for lower ORs with lower thresholds in medium-term studies. Conclusions: The OR for a treatment effect compared with placebo appears consistent across a range of responder cut-points. In medium-term trials, the treatment difference between active drugs suggests that use of a lower threshold would not increase the odds of observing a measured treatment difference

St George's Respiratory Questionnaire Score Predicts Outcomes in Patients with COPD: Analysis of Individual Patient Data in the COPD Biomarkers Qualification Consortium Database.

Background: We aimed to estimate the usefulness of a disease specific health status measure, the St George's Respiratory Questionnaire (SGRQ), to predict outcomes in patients with chronic obstructive pulmonary disease (COPD). Methods: Individual patient-data of 12043 patients from long-term randomized clinical trials (2-4 years' duration) in the COPD Biomarkers Qualification Consortium database were analyzed. The adverse COPD outcomes were: exacerbations of COPD, hospital admissions due to exacerbation and all-cause mortality. Cox proportional hazards regression was used to calculate adjusted hazard ratios (HR) and 95% confidence intervals (CIs) for quartiles of SGRQ scores at baseline and time to first event, and time from first to second event, where appropriate. Results: The risk of adverse COPD outcomes increased with each increasing quartile of SGRQ score for all time to first event analyses. When comparing the lowest versus the highest quartile, the event risk (HRs [95% CIs]) increased by 40% for exacerbations (1.40 [1.29, 1.51]); 2-fold for hospital admissions (2.01 [1.78, 2.28]) and more than 2-fold for all-cause mortality (2.30 [1.91, 2.78]). For second event analyses in a subset of eligible patients, these trends persisted albeit with reduced risk estimates for exacerbations. Conclusions: Among patients with COPD, health status measured by a SGRQ score predicted exacerbations of COPD, hospital admissions due to exacerbations and their recurrence and death after adjustment. These data support the rationale for a health status measure use as a drug development tool and suggest that a health status measure may also have a role in risk assessment for COPD patients in routine medical care

Socioeconomic Status as a Determinant of Health Status Treatment Response in COPD Trials.

Background: Randomized controlled trials (RCTs) often recruit patients from low and high socioeconomic status (SES) countries, but little is known about the effect of SES on clinical outcomes, particularly patient-centered measures of symptomatic benefit. Methods: Combined individual chronic obstructive pulmonary disease (COPD) patient data from the placebo and long-acting bronchodilator arms of 17 RCTs (from the COPD Biomarkers Qualification Consortium database) were analyzed. Health status was measured using the St George's Respiratory Questionnaire (SGRQ) (minimum clinically important difference [MCID]: 4 units). Trials were grouped into short-term (≤12 months) and medium-term (>12 months to 48 months). A participant's country of residence was categorized into Low/Medium or High SES using World Health Organization criteria. Results: Data from 19765 individuals (6109 Low/Medium SES) were available. Patients in Low/Medium SES countries had more severe disease at baseline. Improvement in SGRQ score with placebo was ≈2 units greater in Low/Medium than in High SES countries; at its greatest, the improvement from baseline exceeded the MCID in Low/Medium countries. This difference was maintained for at least 1 year. Improvement with bronchodilator was also greater in Low/Medium versus High SES countries; overall there was no evidence that the treatment effect versus placebo was different between countries of different SES status. Conclusions: Participants in Low/Medium SES countries experienced significantly larger treatment effects, irrespective of treatment group (placebo and bronchodilator). Despite this, COPD patients in Low/Medium SES countries experienced a health status gain from long-acting bronchodilator treatment that is similar to that seen in High SES countries

The COPD Biomarkers Qualification Consortium Database: Baseline Characteristics of the St George's Respiratory Questionnaire Dataset.

The COPD Biomarkers Qualification Consortium (CBQC) is a public-private partnership formed in 2010 with a goal of qualifying biomarkers and clinical assessment tools for use in clinical or nonclinical decision-making and particularly within the regulatory context. The St George's Respiratory Questionnaire (SGRQ) is a measure of health-related quality of life widely used in clinical research. The aim of the CBQC working group on SGRQ was to construct an individual patient level database of clinical trial data that included the SGRQ, to use this to confirm the reliability and validity of the SGRQ as an outcome measure of health status, and investigate its use as a predictor of future events (exacerbations and mortality). This manuscript describes the formulation of the CBQC database and presents the baseline demographic and clinical characteristics of the integrated SGRQ database overall, and by study type (short-term [≤1 year], medium-term [2-4 years] and observational studies). Distribution of baseline SGRQ scores varied little by demographic determinants except for income region in the observational data set (low-middle income countries +10 units compared with high income, p<0.0001) and this observation held across studies. SGRQ scores increased with increasing modified Medical Research Council dyspnea scores (mean differences ranged 6.9-17.9 units) and with increasing airflow limitations (Global initiative for chronic Obstructive Lung Disease grades 1 to 4; differences ranged 4.5-16.1 units), consistent across study types. As a method of cross-sectional comparison, the SGRQ appears to be relatively free of bias from demographic factors although care should be taken when making cross sectional comparisons of scores between patients in countries at different levels of socio-economic development/

Investigation of Non-Stable Processes in Close Binary Ry Scuti

We present results of reanalysis of old electrophotometric data of early type close binary system RY Scuti obtained at the Abastumani Astrophysical Observatory, Georgia, during 1972-1990 years and at the Maidanak Observatory, Uzbekistan, during 1979-1991 years. It is revealed non-stable processes in RY Sct from period to period, from month to month and from year to year. This variation consists from the hundredths up to the tenths of a magnitude. Furthermore, periodical changes in the system's light are displayed near the first maximum on timescales of a few years. That is of great interest with regard to some similar variations seen in luminous blue variable (LBV) stars. This also could be closely related to the question of why RY Sct ejected its nebula.Comment: 11 pages, 6 figures, 2 table

The temperature and chronology of heavy-element synthesis in low-mass stars

Roughly half of the heavy elements (atomic mass greater than that of iron) are believed to be synthesized in the late evolutionary stages of stars with masses between 0.8 and 8 solar masses. Deep inside the star, nuclei (mainly iron) capture neutrons and progressively build up (through the slow-neutron-capture process, or s-process) heavier elements that are subsequently brought to the stellar surface by convection. Two neutron sources, activated at distinct temperatures, have been proposed: 13C and 22Ne, each releasing one neutron per alpha-particle (4He) captured. To explain the measured stellar abundances, stellar evolution models invoking the 13C neutron source (which operates at temperatures of about one hundred million kelvin) are favoured. Isotopic ratios in primitive meteorites, however, reflecting nucleosynthesis in the previous generations of stars that contributed material to the Solar System, point to higher temperatures (more than three hundred million kelvin), requiring at least a late activation of 22Ne. Here we report a determination of the s-process temperature directly in evolved low-mass giant stars, using zirconium and niobium abundances, independently of stellar evolution models. The derived temperature supports 13C as the s-process neutron source. The radioactive pair 93Zr-93Nb used to estimate the s-process temperature also provides, together with the pair 99Tc-99Ru, chronometric information on the time elapsed since the start of the s-process, which we determine to be one million to three million years.Comment: 30 pages, 10 figure

Adding a Little Reality to Building Ontologies for Biology

BACKGROUND: Many areas of biology are open to mathematical and computational modelling. The application of discrete, logical formalisms defines the field of biomedical ontologies. Ontologies have been put to many uses in bioinformatics. The most widespread is for description of entities about which data have been collected, allowing integration and analysis across multiple resources. There are now over 60 ontologies in active use, increasingly developed as large, international collaborations. There are, however, many opinions on how ontologies should be authored; that is, what is appropriate for representation. Recently, a common opinion has been the "realist" approach that places restrictions upon the style of modelling considered to be appropriate. METHODOLOGY/PRINCIPAL FINDINGS: Here, we use a number of case studies for describing the results of biological experiments. We investigate the ways in which these could be represented using both realist and non-realist approaches; we consider the limitations and advantages of each of these models. CONCLUSIONS/SIGNIFICANCE: From our analysis, we conclude that while realist principles may enable straight-forward modelling for some topics, there are crucial aspects of science and the phenomena it studies that do not fit into this approach; realism appears to be over-simplistic which, perversely, results in overly complex ontological models. We suggest that it is impossible to avoid compromise in modelling ontology; a clearer understanding of these compromises will better enable appropriate modelling, fulfilling the many needs for discrete mathematical models within computational biology

Stochastic Theory of Early Viral Infection: Continuous versus Burst Production of Virions

Viral production from infected cells can occur continuously or in a burst that generally kills the cell. For HIV infection, both modes of production have been suggested. Standard viral dynamic models formulated as sets of ordinary differential equations can not distinguish between these two modes of viral production, as the predicted dynamics is identical as long as infected cells produce the same total number of virions over their lifespan. Here we show that in stochastic models of viral infection the two modes of viral production yield different early term dynamics. Further, we analytically determine the probability that infections initiated with any number of virions and infected cells reach extinction, the state when both the population of virions and infected cells vanish, and show this too has different solutions for continuous and burst production. We also compute the distributions of times to establish infection as well as the distribution of times to extinction starting from both a single virion as well as from a single infected cell for both modes of virion production