4,712 research outputs found

    An ab initio HCN and HNC rotational vibrationallinelist for astronomy

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    We present a new ab initio HCN/HNC linelist. The linelist forms themost accurate and extensive HCN/HNC data set presently in existence.The data contain rotation vibration line frequencies and line strengths,for all transitions that are not rigorously dipole forbidden, between stateswith energy less than 18 000 cm-1 and with J ? 60

    The role of non-gray model atmospheres in the evolution of low mass metal poor stars

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    Gray model atmospheres are generally considered a reasonable approximation to make upon stars of mass greater than about 0.6 M-circle dot. Here we show that non-gray atmospheres can significantly affect evolutionary models, with masses up to 0.9 M-circle dot. The effect of including a non-gray atmosphere is strongest in the pre-main and post-main Sequence. This may have implications for the ages of the oldest globular clusters

    Temperature dependent partition functions and equilibrium constant for HCN and HNC

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    Ab initio vibration-rotation energy levels are summed to estimate a partition function for the total HCN system. By assigning individual levels to HCN and HNC, separate partition functions are obtained for the isomers. These are used to give a temperature dependent equilibrium constant which suggests that at temperatures typical of cool carbon stars, about 20% of the HCN system is actually HNC. Errors in the partition functions and equilibrium constant are estimated. (C) 2002 American Institute of Physics

    The Effect of the Electron Donor H⁺₃ on the Pre-Main-Sequence and Main-Sequence Evolution of Low-Mass, Zero-Metallicity Stars

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    H₃⁺ has been shown (1991 work of Lenzuni and coworkers) to be the dominant positive ion in a zero-metallicity gas at low temperature and intermediate to high density. It therefore affects both the number of free electrons and the opacity of the gas. The most recent H₃⁺ partition function (1995 work of Neale & Tennyson) is an order of magnitude larger at 4000 K than all previous partition functions, implying that H₃⁺ is a more important electron donor than previously thought. Here we present new Rosseland mean opacities for a hydrogen-helium gas of 1000 K ≤ T ≤ 9000 K and -14 ≤ log₁₀ [ρ (g cm⁻³)] ≤ -2. In the calculation of these opacities, we have made use of the latest collision-induced absorption data as well as the most recent H₃⁺ partition function and line opacity data. It is shown that these updated and new sources of opacity give rise to a Rosseland mean opacity for a hydrogen-helium gas that is, in general, greater than that calculated in earlier works. The new opacity data are then used to model the evolution of low-mass (0.15-0.8 M_{☉}), zero-metallicity stars, from pre-main-sequence collapse to main-sequence turnoff. To investigate the effect of H₃⁺ on the evolution of low-mass, zero-metallicity stars, we repeat our calculations neglecting H₃⁺ as a source of electrons and line opacity. We find that H₃⁺ can have an effect on the structure and evolution of stars of mass ~0.5 M_{☉} or less. A gray atmosphere is used for the calculation, which is sufficient to demonstrate that H₃⁺ affects the evolution of very low mass stars to a greater degree than previously believed

    Hazards of tube thoracostomy in patients on a ventilator

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    A patient with post-pneumonia empyema complicated by type-2 respiratory failure required mechanical ventilation as part of his therapy. A pneumothorax was noted on his chest radiograph. This was treated with an intercostal chest drain (ICD). Unfortunately, he was still hypoxic, his subcutaneous emphysema was worsening and the ICD was bubbling. A computed tomography (CT) scan of chest demonstrated that the ICD has penetrated the right upper lobe parenchyma. A new ICD was inserted and the previous one was removed. Although both hypoxia and subcutaneous emphysema improved, the patient chronically remained on mechanical ventilation

    Ciprofloxacin during upper respiratory tract infections to reduce Pseudomonas aeruginosa infection in paediatric cystic fibrosis: a pilot study.

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    OBJECTIVES: Acute viral respiratory illnesses are associated with acquisition of Pseudomonas aeruginosa infection in cystic fibrosis (CF) patients. This study aimed to pilot a protocol for a randomized controlled trial to determine whether oral antipseudomonal antibiotics used at the onset of such episodes might delay onset of infection with this organism. METHODS: A total of 41 children with CF aged 2-14 years, without chronic Pseudomonas infection, were randomized to receive ciprofloxacin (n = 28) or placebo (n = 13) at the onset of acute viral respiratory infections on an intention to treat basis, during a study period of up to 32 months. RESULTS: There were no unexpected adverse events believed related to the use of the study medication. The rate of withdrawal from the study was low (approximately 7%) and did not differ between groups. Randomization was effective and acceptable to participants. Primary and secondary outcome measures all favoured active treatment, but there were no significant between group differences. The median rate of Pseudomonas isolates was 0/patient/year (interquartile range 0-0.38) in both the active and placebo groups. Kaplan-Meier survival curves showed no significant difference in time to first Pseudomonas isolate between groups. CONCLUSIONS: This study demonstrated the clinical feasibility of using oral ciprofloxacin in CF patients at times of viral infection. Within this sample size, no significant association was found between active treatment and decreased growth of Pseudomonas in follow-up microbiological samples. A definitive study would require at least 320 children to demonstrate significant differences in the rate of pseudomonal isolates

    Teprotumumab for Thyroid-Associated Ophthalmopathy

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    BACKGROUND: Thyroid-associated ophthalmopathy, a condition commonly associated with Graves’ disease, remains inadequately treated. Current medical therapies, which primarily consist of glucocorticoids, have limited efficacy and present safety concerns. Inhibition of the insulin-like growth factor I receptor (IGF-IR) is a new therapeutic strategy to attenuate the underlying autoimmune pathogenesis of ophthalmopathy. / METHODS: We conducted a multicenter, double-masked, randomized, placebo-controlled trial to determine the efficacy and safety of teprotumumab, a human monoclonal antibody inhibitor of IGF-IR, in patients with active, moderate-to-severe ophthalmopathy. A total of 88 patients were randomly assigned to receive placebo or active drug administered intravenously once every 3 weeks for a total of eight infusions. The primary end point was the response in the study eye. This response was defined as a reduction of 2 points or more in the Clinical Activity Score (scores range from 0 to 7, with a score of ≥3 indicating active thyroid-associated ophthalmopathy) and a reduction of 2 mm or more in proptosis at week 24. Secondary end points, measured as continuous variables, included proptosis, the Clinical Activity Score, and results on the Graves’ ophthalmopathy–specific quality-of-life questionnaire. Adverse events were assessed. / RESULTS: In the intention-to-treat population, 29 of 42 patients who received teprotumumab (69%), as compared with 9 of 45 patients who received placebo (20%), had a response at week 24 (P<0.001). Therapeutic effects were rapid; at week 6, a total of 18 of 42 patients in the teprotumumab group (43%) and 2 of 45 patients in the placebo group (4%) had a response (P<0.001). Differences between the groups increased at subsequent time points. The only drug-related adverse event was hyperglycemia in patients with diabetes; this event was controlled by adjusting medication for diabetes. / CONCLUSIONS: In patients with active ophthalmopathy, teprotumumab was more effective than placebo in reducing proptosis and the Clinical Activity Score. (Funded by River Vision Development and others; ClinicalTrials.gov number, NCT01868997.
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