3,507 research outputs found

    Ab initio Molecular Orbital Studies of the Vibrational Spectra of some van der Waals Complexes. Part 4. Complexes of Sulphur Dioxide with Carbon Dioxide, Carbonyl Sulphide, Carbon Disulphide and Nitrous Oxide

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    The binary complexes formed between sulphur dioxide, as electron donor, and the series carbon dioxide, carbonyl sulphide and carbon disulphide, as electron acceptors, have been studied by means of ab initio molecular orbital theory. The optimized structures, the interaction energies and the vibrational spectra have been determined, and the effect of successive substitution of sulphur for oxygen atoms in the electron acceptor molecules has been established. Nitrous oxide, which is isoelectronic with carbon dioxide, has also been included among the electron acceptors, but the properties of the complex formed between sulphur dioxide and nitrous oxide are substantially different from those of the other three complexes.Keywords: Ab initio calculations, molecular complexes, sulphur dioxide, carbon dioxide, carbonyl sulphide, carbon disulphide, nitrous oxide, molecular structures, interaction energies, vibrational spectraPDF and Supplementry file attache

    Effects of Turbulence, Eccentricity Damping, and Migration Rate on the Capture of Planets into Mean Motion Resonance

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    Pairs of migrating extrasolar planets often lock into mean motion resonance as they drift inward. This paper studies the convergent migration of giant planets (driven by a circumstellar disk) and determines the probability that they are captured into mean motion resonance. The probability that such planets enter resonance depends on the type of resonance, the migration rate, the eccentricity damping rate, and the amplitude of the turbulent fluctuations. This problem is studied both through direct integrations of the full 3-body problem, and via semi-analytic model equations. In general, the probability of resonance decreases with increasing migration rate, and with increasing levels of turbulence, but increases with eccentricity damping. Previous work has shown that the distributions of orbital elements (eccentricity and semimajor axis) for observed extrasolar planets can be reproduced by migration models with multiple planets. However, these results depend on resonance locking, and this study shows that entry into -- and maintenance of -- mean motion resonance depends sensitively on migration rate, eccentricity damping, and turbulence.Comment: 43 pages including 14 figures; accepted for publication in The Astrophysical Journa

    The effect of gefapixant, a P2X3 antagonist, on cough reflex sensitivity: A randomised placebo-controlled study

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    We evaluated the effect of gefapixant on cough reflex sensitivity to evoked tussive challenge.In this phase 2, double-blind, two-period study, patients with chronic cough (CC) and healthy volunteers (HV) were randomised to single-dose gefapixant 100 mg or placebo in a crossover fashion. Sequential inhalational challenges with ATP, citric acid, capsaicin and distilled water were performed 1, 3 and 5 h after dosing. Mean concentrations evoking ≄2 coughs (C2) and ≄5 coughs (C5) post dose versus baseline were co-primary endpoints. Objective cough frequency (coughs·h−1) over 24 h and a cough severity visual analogue scale (VAS) were assessed in CC patients. Adverse events were monitored.24 CC patients and 12 HV were randomised (mean age 61 and 38 years, respectively). The cough challenge threshold increased for ATP by 4.7-fold (C2, p≀0.001) and 3.7-fold (C5, p=0.007) for gefapixant versus placebo in CC patients; in HV, C2 and C5 increased 2.4-fold (C2, p=0.113; C5, p=0.003). The distilled water C2 and C5 thresholds increased significantly (

    Multicentre, prospective, randomised, open-label, blinded end point trial of the efficacy of allopurinol therapy in improving cardiovascular outcomes in patients with ischaemic heart disease: protocol of the ALL-HEART study

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    Introduction Ischaemic heart disease (IHD) is one of the most common causes of death in the UK and treatment of patients with IHD costs the National Health System (NHS) billions of pounds each year. Allopurinol is a xanthine oxidase inhibitor used to prevent gout that also has several positive effects on the cardiovascular system. The ALL-HEART study aims to determine whether allopurinol improves cardiovascular outcomes in patients with IHD. Methods and Analysis The ALL-HEART study is a multicentre, controlled, prospective, randomised, open-label blinded end point (PROBE) trial of allopurinol (up to 600 mg daily) versus no treatment in a 1:1 ratio, added to usual care, in 5215 patients aged 60 years and over with IHD. Patients are followed up by electronic record linkage and annual questionnaires for an average of 4 years. The primary outcome is the composite of non-fatal myocardial infarction, non-fatal stroke or cardiovascular death. Secondary outcomes include all-cause mortality, quality of life and cost-effectiveness of allopurinol. The study will end when 631 adjudicated primary outcomes have occurred. The study is powered at 80% to detect a 20% reduction in the primary end point for the intervention. Patient recruitment to the ALL-HEART study started in February 2014. Ethics and Dissemination The study received ethical approval from the East of Scotland Research Ethics Service (EoSRES) REC 2 (13/ES/0104). The study is event-driven and results are expected after 2019. Results will be reported in peer-reviewed journals and at scientific meetings. Results will also be disseminated to guideline committees, NHS organisations and patient groups

    Men who have sex with men in Great Britain: comparing methods and estimates from probability and convenience sample surveys.

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    OBJECTIVE: To examine sociodemographic and behavioural differences between men who have sex with men (MSM) participating in recent UK convenience surveys and a national probability sample survey. METHODS: We compared 148 MSM aged 18-64 years interviewed for Britain's third National Survey of Sexual Attitudes and Lifestyles (Natsal-3) undertaken in 2010-2012, with men in the same age range participating in contemporaneous convenience surveys of MSM: 15 500 British resident men in the European MSM Internet Survey (EMIS); 797 in the London Gay Men's Sexual Health Survey; and 1234 in Scotland's Gay Men's Sexual Health Survey. Analyses compared men reporting at least one male sexual partner (past year) on similarly worded questions and multivariable analyses accounted for sociodemographic differences between the surveys. RESULTS: MSM in convenience surveys were younger and better educated than MSM in Natsal-3, and a larger proportion identified as gay (85%-95% vs 62%). Partner numbers were higher and same-sex anal sex more common in convenience surveys. Unprotected anal intercourse was more commonly reported in EMIS. Compared with Natsal-3, MSM in convenience surveys were more likely to report gonorrhoea diagnoses and HIV testing (both past year). Differences between the samples were reduced when restricting analysis to gay-identifying MSM. CONCLUSIONS: National probability surveys better reflect the population of MSM but are limited by their smaller samples of MSM. Convenience surveys recruit larger samples of MSM but tend to over-represent MSM identifying as gay and reporting more sexual risk behaviours. Because both sampling strategies have strengths and weaknesses, methods are needed to triangulate data from probability and convenience surveys

    Effect of Antiplatelet Therapy (Aspirin + Dipyridamole Versus Clopidogrel) on Mortality Outcome in Ischemic Stroke

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    The optimal regimen of antiplatelet therapy for secondary prevention in noncardioembolic ischemic stroke remains controversial. We aimed to determine which regimen was associated with the greatest reduction in adverse outcomes. We analysed prospectively collected data from the Norfolk and Norwich University Hospital Stroke Register (NNUHSR). The sample population consisted of 3,572 participants (mean age 74.96 ± 12.67) with ischemic stroke, who were consecutively admitted between 2003-2015. Patients were placed on one of three antiplatelet regimens at hospital discharge; aspirin monotherapy, aspirin plus dipyridamole and clopidogrel. Clopidogrel and aspirin plus dipyridamole was compared to aspirin. A direct comparison between clopidogrel and aspirin plus dipyridamole was also performed. Outcomes included all-cause mortality and a combined endpoint of all-cause mortality and incidence of major adverse cardiac events (stroke or myocardial infarction). Cox-regression models adjusted for potential confounders at the following time periods after discharge; 0-90 days, 91-365 days and 1-3 years. Aspirin plus dipyridamole was associated with a lower risk of mortality at 0-90 days; HR 0.62 (0.43-0.91). Clopidogrel was associated with a lower risk of mortality at 1-3 years; HR of 0.39 (0.26-0.60). Similar HRs were observed for the the corresponding time points in the composite outcome. In conclusion Patients with non-cardioembolic stroke may gain maximum benefit from aspirin plus dipyridamole initially (≀1 year) with a subsequent switch to clopidogrel, with regard to mortality and MACE outcomes

    Distinctive genotypes in infants with T-cell acute lymphoblastic leukaemia

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    Infant T-cell acute lymphoblastic leukaemia (iT-ALL) is a very rare and poorly defined entity with a poor prognosis. We assembled a unique series of 13 infants with T-ALL, which allowed us to identify genotypic abnormalities and to investigate prenatal origins. Matched samples (diagnosis/remission) were analysed by single nucleotide polymorphism-array to identify genomic losses and gains. In three cases, we identified a recurrent somatic deletion on chromosome 3. These losses result in the complete deletion of MLF1 and have not previously been described in T-ALL. We observed two cases with an 11p13 deletion (LMO2-related), one of which also harboured a deletion of RB1. Another case presented a large 11q14·1-11q23·2 deletion that included ATM and only five patients (38%) showed deletions of CDKN2A/B. Four cases showed NOTCH1 mutations; in one case FBXW7 was the sole mutation and three cases showed alterations in PTEN. KMT2A rearrangements (KMT2A-r) were detected in three out of 13 cases. For three patients, mutations and copy number alterations (including deletion of PTEN) could be backtracked to birth using neonatal blood spot DNA, demonstrating an in utero origin. Overall, our data indicates that iT-ALL has a diverse but distinctive profile of genotypic abnormalities when compared to T-ALL in older children and adults

    Using a novel methodology to map Post-COVID services for children and young people in England: a web-based systematic search

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    Background: Post-COVID Condition (PCC), also known as ‘Long COVID,’ refers to persistent symptoms following a coronavirus 2 (SARS-CoV-2) infection. The prevalence of PCC in children and adolescents varies, impacting multiple body systems and affecting daily functioning. Specialised paediatric hubs were established in England to address the needs of young individuals with PCC. Additional local services also emerged, yet patients report challenges accessing services. To better understand the landscape of paediatric PCC services, we used a novel methodology using a web-based systematic search. Methods: A web-based search was conducted in July 2023 using DEVONagent Pro. Search terms related to Long COVID and Pediatrics in England. Eligible sources providing information on PCC services for children and young people were included. A supplementary manual search and NHS England Post-COVID Network were also consulted. Data extraction included service location, characteristics, and referral pathways. Population estimates were derived from UK Census data. Results: Among 342 identified records, 27 services met eligibility criteria, distributed unevenly across regions. Specialised hubs covered 13 locations, while additional services were concentrated in the South of England and London. Services varied in team composition, age range treated, and support offered. A lack of standardised approaches for paediatric PCC was evident. Discussion: We used a novel methodology for systematically mapping online resources, providing valuable insights into service accessibility and aiding the identification of potential gaps. We observed geographical disparities in access to paediatric PCC services and the absence of standardised approaches in managing symptoms. Given the challenges faced by young individuals seeking support for their PCC the need for equitable and standardised care became apparent. The study contributes to closing the research-practice gap and calls for further research to identify effective treatments for paediatric PCC, acknowledging the diversity of reported symptoms and the importance of tailored approaches

    Distant echoes: evoking the soundscapes of the past in the radio documentary series Noise: a human history

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    This article asks whether radio can ever successfully evoke an accurate sense of the sound of the past. It does so through a reflective critical analysis of the 2013 BBC Radio 4 documentary series, Noise: A Human History, by its own writer and presenter. It explores how the ‘sound design’ of the series met the challenge of providing a longue durĂ©e history of sound without having recourse to authentic sound archive recordings for most of the period being covered. Through an analysis of key sequences, and by highlighting the significance of the broader context of production, it argues that it is possible for epistemologically valuable history to emerge, even via a medium that treats sound more as a device for evoking the imagination than as something possessing evidential status in itself. The article does this by invoking the series as a practical example of ‘historical acoustemology’, and by suggesting that in radio notions of subjectivity and perceptual mimesis are key to understanding the medium's success. In doing so, the article calls for a redefinition of the notion of the radiogenic – arguing for a move away from seeing ‘raw’ sound as the key ingredient of sound design, and towards greater attention to the influence of radio's other characteristics as a time-based, institutionally-produced mass medium
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