358 research outputs found

    A general method for elicitation, imputation, and sensitivity analysis for incomplete repeated binary data.

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    We develop and demonstrate methods to perform sensitivity analyses to assess sensitivity to plausible departures from missing at random in incomplete repeated binary outcome data. We use multiple imputation in the not at random fully conditional specification framework, which includes one or more sensitivity parameters (SPs) for each incomplete variable. The use of an online elicitation questionnaire is demonstrated to obtain expert opinion on the SPs, and highest prior density regions are used alongside opinion pooling methods to display credible regions for SPs. We demonstrate that substantive conclusions can be far more sensitive to departures from the missing at random assumption (MAR) when control and intervention nonresponders depart from MAR differently, and show that the correlation of arm specific SPs in expert opinion is particularly important. We illustrate these methods on the iQuit in Practice smoking cessation trial, which compared the impact of a tailored text messaging system versus standard care on smoking cessation. We show that conclusions about the effect of intervention on smoking cessation outcomes at 8 week and 6 months are broadly insensitive to departures from MAR, with conclusions significantly affected only when the differences in behavior between the nonresponders in the two trial arms is larger than expert opinion judges to be realistic

    Doping driven magnetic instabilities and quantum criticality of NbFe2_{2}

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    Using density functional theory we investigate the evolution of the magnetic ground state of NbFe2_{2} due to doping by Nb-excess and Fe-excess. We find that non-rigid-band effects, due to the contribution of Fe-\textit{d} states to the density of states at the Fermi level are crucial to the evolution of the magnetic phase diagram. Furthermore, the influence of disorder is important to the development of ferromagnetism upon Nb doping. These findings give a framework in which to understand the evolution of the magnetic ground state in the temperature-doping phase diagram. We investigate the magnetic instabilities in NbFe2_{2}. We find that explicit calculation of the Lindhard function, χ0(q)\chi_{0}(\mathbf{q}), indicates that the primary instability is to finite q\mathbf{q} antiferromagnetism driven by Fermi surface nesting. Total energy calculations indicate that q=0\mathbf{q}=0 antiferromagnetism is the ground state. We discuss the influence of competing q=0\mathbf{q}=0 and finite q\mathbf{q} instabilities on the presence of the non-Fermi liquid behavior in this material.Comment: 8 pages, 7 figure

    Image-based software solutions for advanced materials processing and characterization

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    This is the author accepted manuscript. The final version is available from Elsevier via the DOI in this recordNew image-based solutions are being developed for advanced materials processing and characterization, which involve working with and creating high-quality models from scan data (such as MRI, CT, micro-CT…). Techniques involving the reconstruction and analysis of 3D materials data can accurately reconstruct internal structures, even to the nano level, and generate high-quality meshes suitable for design and simulation applications. By looking at key techniques and their applications, it is possible to better understand the wider impact and benefits of image-based modelling for industry when working with advanced materials

    Retrofitting Large Refrigeration Systems with R-134a

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    Access to palivizumab among children at high risk of respiratory syncytial virus complications in English hospitals

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    Objectives: Palivizumab is a monoclonal antibody which can prevent infection with respiratory syncytial virus (RSV). Due to its high cost, it is recommended for high-risk infants only. We aimed to determine the proportion of infants eligible for palivizumab treatment in England who receive at least one dose. / Methods: We used the Hospital Treatment Insights database containing hospital admission records linked to hospital pharmacy dispensing data for 43/153 hospitals in England. Infants born between 2010 and 2016 were considered eligible for palivizumab if their medical records indicated chronic lung disease (CLD), congenital heart disease (CHD), or severe immunodeficiency (SCID), and they met additional criteria based on gestational age at birth and age at start of the RSV season (beginning of October). We calculated the proportion of infants who received at least one dose of palivizumab in their first RSV season, and modelled the odds of treatment according to multiple child characteristics using logistic regression models. / Results: We identified 3,712 eligible children, of whom 2,479 (67%) had complete information on all risk factors. Palivizumab was prescribed to 832 of eligible children (34%). Being born at <30 weeks’ gestation, aged <6 months at the start of RSV season, and having two or more of CLD, CHD or SCID were associated with higher odds of treatment. / Conclusion: In England, palivizumab is not prescribed to the majority of children who are eligible to receive it. Doctors managing these infants may be unfamiliar with the eligibility criteria or constrained by other considerations, such as cost

    Engineering of an environmental isolate of bacillus megaterium for biochemical production under supercritical CO2

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    Continuous processing is a mainstay for chemical production but is far less common for biochemical processes. The increase in productivity and corresponding decrease in costs make continuous processing an intriguing option for bulk chemicals where price is a major consideration. Among the various challenges of continuous bioprocessing are the risks of contamination and the toxicity of the target products. Supercritical carbon dioxide (scCO2) may provide a means to address both of these issues. scCO2 is an attractive substitute for conventional organic solvents due to its unique transport and thermodynamic properties, its renewability and labile nature, and its high solubility for compounds such as alcohols, ketones and aldehydes. scCO2 is also known for its broad microbial lethality. The isolation and engineering of a microbe that is capable of growth and production in the presence of scCO2 thus represents an opportunity to create a production environment that is both resist to contamination and capable of sequestering toxic products through phase separation. Using a targeted bioprospecting approach by sampling fluid from a natural, deep-subsurface scCO2 well, a strain of Bacillus megaterium was isolated that is able to germinate and grow in the presence of scCO2. Transformation is possible using a protoplast-based method, which permitted the identification of promoters capable of inducible heterologous protein expression in both aerobic and anaerobic conditions. A xylose-inducible promoter was evaluated under scCO2 and found to have similar expression under both conditions. We engineered the B. megaterium strain to produce isobutanol from 2-ketoisovalerate by introducing a two-enzyme pathway (2- ketoisovalerate decarboxylase (KivD) and alcohol dehydrogenase (Adh)). Due to the strong partition of the aldehyde to the scCO2 phase, we tested five homologous Adh enzymes and found that YqhD from E. coli resulted in greater than 85% conversion when grown aerobically. Isobutanol production was also observed when our recombinant strain was cultured under scCO2. Finally, we have developed a process model for an integrated bioprocess and have found conditions that are comparable if not better than existing in situ extraction techniques such as gas stripping. Boock, J.T., A.J.E. Freedman, G.A. Tompsett, S.K. Muse, A.J. Allen, L.A. Jackson, B. Castro-Dominguez, M.T. Timko, K.L.J. Prather (co-corresponding author), J.R. Thompson. 2019. “Engineered microbial biofuel production and recovery under supercritical carbon dioxide.” Nat. Commun. 10:587. DOI: 10.1038/s41467- 019-08486-6

    Evidence-Based Guideline on Laparoscopy in Pregnancy: Commissioned by the British Society for Gynaecological Endoscopy (BSGE) Endorsed by the Royal College of Obstetricians & Gynaecologists (RCOG).

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    Laparoscopy is widely utilised to diagnose and treat acute and chronic, gynaecological and general surgical conditions. It has only been in recent years that laparoscopy has become an acceptable surgical alternative to open surgery in pregnancy. To date there is little clinical guidance pertaining to laparoscopic surgery in pregnancy. This is why the BSGE commissioned this guideline. MEDLINE, EMBASE, CINAHL and the Cochrane library were searched up to February 2017 and evidence was collated and graded following the NICE-approved process. The conditions included in this guideline are laparoscopic management of acute appendicitis, acute gall bladder disease and symptomatic benign adnexal tumours in pregnancy. The intended audience for this guideline is obstetricians and gynaecologists in secondary and tertiary care, general surgeons and anaesthetists. However, only laparoscopists who have adequate laparoscopic skills and who perform complex laparoscopic surgery regularly should undertake laparoscopy in pregnant women, since much of the evidence stems from specialised centres

    Modern microwave methods in solid state inorganic materials chemistry: from fundamentals to manufacturing

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    Synthesis and properties of La-doped CaFe2As2 single crystals with Tc = 42.7 K

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    Large single crystals of La-doped CaFe2As2 were successfully synthesized by the FeAs self-flux method. The x-ray diffraction patterns suggest high crystalline quality and c-axis orientation. By substitution of trivalent La3+ ions for divalent Ca2+, the resistivity anomaly in the parent compound CaFe2As2 is completely suppressed and a superconducting transition reaches the value of 42.7 K, which is higher than that of about 30 K reported in Saha S. R. et al., arXiv:1105.4798v1. The upper critical field has been determined with the magnetic field along ab-plane and c-axis, yielding an anisotropy of about 3.3.Comment: 13 pages, 5 figure

    Structural properties and superconductivity of SrFe2As2-xPx and CaFe2As2-yPy

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    The SrFe2As2-xPx and CaFe2As2-yPy materials were prepared by a solid state reaction method. X-ray diffraction measurements indicate the single-phase samples can be successfully obtained for SrFe2As2-xPx and CaFe2As2-yPy samples. Clear contraction of the lattice parameters are clearly determined due to the relatively smaller P ions substation for As. The SDW instability associated with tetragonal to orthorhombic phase transition is suppressed visibly in both systems following with the increase of P contents. The highest superconducting transitions are respectively observed at about 27 K in SrFe2As1.3P0.7 and at about 13 K in CaFe2As1.7P0.3.Comment: 11 pages, 5 figures, 2 table
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