4,741 research outputs found
An ab initio HCN and HNC rotational vibrationallinelist for astronomy
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
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
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
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
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
Recommended from our members
Impact response of additively manufactured metallic hybrid lattice materials
Additive manufacturing (AM) enables the design of new cellular materials for blast and impact mitigation by allowing novel material-geometry combinations to be realised and examined at a laboratory scale. However, design of these materials requires an understanding of the relationship between the AM process and material properties at different length scales: from the microstructure to geometric feature rendition to overall dynamic performance. To date, there remain significant uncertainties about both the potential benefits and pitfalls of using AM to design and optimise cellular materials for dynamic energy absorbing applications. This experimental investigation focuses on the out-of-plane compression of stainless steel cellular materials fabricated using selective laser melting (SLM), and makes two specific contributions. First, we demonstrate how the AM process itself influences the characteristics of these cellular materials across a range of length scales, and, crucially, how this influences the dynamic deformation. Secondly, we demonstrate how an AM route can be used to add geometric complexity to the cell structure, creating a versatile basis for future geometry optimisation. Starting with an AM square honeycomb (the reference case), we add porosity to the walls by replacing them with a lattice truss, while maintaining the same relative density. This geometry hybridisation is an approach uniquely suited to this manufacturing route. It is found that the hybrid lattice-walled honeycomb geometry significantly outperforms previously reported AM lattices in terms of specific strength, specific energy absorption, and energy absorption efficiency. It is also found that the hybrid geometry outperforms the benchmark metallic square honeycomb in terms of energy absorption efficiency in the intermediate impact velocity regime (i.e. between quasi-static loading and loading rates at which wave propagation effects begin to become pronounced), a regime in which the collapse is dominated by dynamic buckling effects.The authors are grateful to AWE for financial support
Ciprofloxacin during upper respiratory tract infections to reduce Pseudomonas aeruginosa infection in paediatric cystic fibrosis: a pilot study.
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
Performance of arthroscopic irrigation systems assessed with automatic blood detection
Biomechanical EngineeringMechanical, Maritime and Materials Engineerin
Teprotumumab for Thyroid-Associated Ophthalmopathy
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.
- …