Muon spin rotation studies of niobium for superconducting RF applications

In this work we investigate superconducting properties of niobium samples via application of the muon spin rotation/relaxation (muSR) technique. We employ for the first time the muSR technique to study samples that are cutout from large and small grain 1.5 GHz radio frequency (RF) single cell niobium cavities. The RF test of these cavities was accompanied by full temperature mapping to characterize the RF losses in each of the samples. Results of the muSR measurements show that standard cavity surface treatments like mild baking and buffered chemical polishing (BCP) performed on the studied samples affect their surface pinning strength. We find an interesting correlation between high field RF losses and field dependence of the sample magnetic volume fraction measured via muSR. The muSR line width observed in ZF-muSR measurements matches the behavior of Nb samples doped with minute amounts of Ta or N impurities. An upper bound for the upper critical field Hc2 of these cutouts is found.Comment: 20 pages, 14 figure

The Birmingham Boron Neutron Capture Therapy (BNCT) project : developments towards selective internal particle therapy

This paper will review progress on two aspects of the Birmingham BNCT project. Firstly on evaluation of the effects of high and low LET radiations when delivered simultaneously, and secondly on attempts to optimise delivery of the boron carrier compound BPA through pharmacokinetic studies. Simultaneous or non-simultaneous irradiations of V79 cells with alpha-particle and X-ray irradiations were performed. Alpha doses of 2 and 2.5 Gy were chosen and the impact on survival when delivered separately or simultaneously with variable doses of X-rays was evaluated. The pharmacokinetics of the delivery of a new formulation of BPA (BPA-mannitol) are being investigated in brain tumour patients through a study with 2 × 2 design featuring intravenous and intracarotid artery infusion of BPA, with or without a mannitol bolus. On the combined effect of low and high LET radiations, a synergistic effect was observed when alpha and X-ray doses are delivered simultaneously. The effect is only present at the 2.5 Gy alpha dose and is a very substantial effect on both the shape of the survival curve and the level of cell killing. This indicates that the alpha component may have the effect of inhibiting the repair of damage from the low LET radiation dose delivered simultaneously. On the pharmacokinetics of BPA, data on the first three cohorts indicate that bioavailability of BPA in brain ECF is increased substantially through the addition of a mannitol bolus, as well as by the use of intracarotid artery route of infusion. In both cases, for some patients the levels after infusion approach those seen in blood, whereas the ECF levels for intravenous infusion without mannitol are typically less than 10% of the blood values

An evaluation of the capability of data conversion of impression creep test

High temperature power plant components are now working far beyond their operative designed life. Establishing their in-service material properties has become a matter of significant concern for power generation companies. Advantages for the assessment of creep material properties may come from miniature specimen creep testing techniques, like impression creep testing method, which can be treated as a quasistatic non-destructive technique and requires a small volume of material that can be scooped from in-service critical components, and can produce reliable secondary creep data. This paper presents an overview of impression creep testing method to highlight the capability in determining the minimum creep strain rate data by use of conversion relationships that relates uniaxial creep test data and impression creep test data. Stepped-load and stepped-temperature impression creep tests are also briefly described. Furthermore, the paper presents some new impression creep test data and their correlation with uniaxial data, obtained from P91, P92 and ½CrMoV steels at different stresses and temperatures. The presented data, in terms of creep strain rate against the reference uniaxial stress, are useful for calibration of impression creep testing technique and provide further comparative results for the evaluation of the reliability of the method in determining secondary creep properties

A 64-pixel Positron-Sensitive Surgical Probe

We report on the continued development of a 64-pixel positron-sensitive surgical probe with a dual-layer detector and multi-anode PMT. An 8 x 8 array of this plastic scintillators in teh first layer detects positrons and a matched GSO crystal array in the second layer detects annihilation 511 keV gammas, which are required to be in coincidence with the detected positrons. Also, the 64 PMT anode signals are differentiated and an overshoot threshold is applied to separate the fast decay plastic anode signals from the slower GSO signals. Finally, an energy threshold is applied to the summed anode signal to distinguish 511 keV gammas from the 140 keV gammas commonly used in sentinel lymph node (SLN) surgery. Previously we reported on how these signal selection criteria were individually tested and optimized based on 9 channels of prototype electronics [1-2]. Currently the electronics shave been upgraded to Xilinx® programmable components, allowing on-the-fly alteration of signal selection criteria, and all 64 channels are operational. Initial measurements of the complete 64-pixel probe were conducted using 18F-FDG positron sources and 18F-FDG and 99mTcphantoms (background 511 keV and 140 keV gammas), simulating lesions in the SLN surgery environment. The average positron sensitivity is measured to be 3.0-7.0 kcps/µCi at different signal selection criteria. The lower bound on sensitivity corresponds to settings optimized for high image resolution and high background rejection ability. The upper bound on sensitivity corresponds to settings optimized for high sensitivity at the cost of lower image resolution and lower background rejection ability. The measured true-to-background contrast in the presence of clinically observed levels of 511 keV and 140 keV background gammas is ~3:1 for a tumor-to-background uptake ratio of 5:1. Performance measurements of the complete 64-pixel probe including sensitivity, true-to-background ratio, and the pixel separation ability are presented

The Quiet-Sun Photosphere and Chromosphere

The overall structure and the fine structure of the solar photosphere outside active regions are largely understood, except possibly important roles of a turbulent near-surface dynamo at its bottom, internal gravity waves at its top, and small-scale vorticity. Classical 1D static radiation-escape modelling has been replaced by 3D time-dependent MHD simulations that come closer to reality. The solar chromosphere, in contrast, remains ill-understood although its pivotal role in coronal mass and energy loading makes it a principal research area. Its fine structure defines its overall structure, so that hard-to-observe and hard-to-model small-scale dynamical processes are the key to understanding. However, both chromospheric observation and chromospheric simulation presently mature towards the required sophistication. The open-field features seem of greater interest than the easier-to-see closed-field features.Comment: Accepted for special issue "Astrophysical Processes on the Sun" of Phil. Trans. Royal Soc. A, ed. C. Parnell. Note: clicking on the year in a citation opens the corresponding ADS abstract page in the browse

Validation of the Dutch translation of the quality of recovery-15 scale

BACKGROUND: The 15-item Quality of Recovery-15 (QoR-15) scale is strongly recommended as a standard patient-reported outcome measure assessing the quality of recovery after surgery and anesthesia in the postoperative period. This study aimed to validate the Dutch translation of the questionnaire (QoR-15NL). MATERIALS AND METHODS: An observational, prospective, single-centre cohort study was conducted. Patients who underwent surgery under general anesthesia completed the QoR-15NL (preoperatively (t1) and twice postoperatively (t2 and t3)) and a visual analogue scale (VAS) for general recovery at t2. A psychometric evaluation was performed to assess the QoR-15NL's validity, reliability, responsiveness, reproducibility and feasibility. RESULTS: Two hundred and eleven patients agreed to participate (recruitment rate 94%), and 165 patients were included (completion rate 78%). The QoR-15NL score correlated with the VAS for general recovery (rs = 0.59). Construct validity was further demonstrated by confirmation of expected negative associations between the QoR-15NL and duration of surgery (rs = -0.25), duration of Post Anesthesia Care Unit stay (rs = -0.31), and duration of hospital stay (rs = -0.27). The QoR-15NL score decreased significantly according to the extent of surgery. Cronbach's alpha was 0.87, split-half reliability was 0.8, and the test-retest intra-class coefficient was 0.93. No significant floor- or ceiling effect was observed. CONCLUSION: The QoR-15NL scale is a valid, easy-to-use, and reliable outcome assessment tool with high responsiveness for patient-reported quality of recovery after surgery and general anesthesia in the Dutch-speaking population. The QoR-15NL's measurement properties are comparable to the original questionnaire and other translated versions. TRIAL REGISTRATION: not applicable

The nuclear receptors of Biomphalaria glabrata and Lottia gigantea: Implications for developing new model organisms

© 2015 Kaur et al. This is an open access article distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are creditedNuclear receptors (NRs) are transcription regulators involved in an array of diverse physiological functions including key roles in endocrine and metabolic function. The aim of this study was to identify nuclear receptors in the fully sequenced genome of the gastropod snail, Biomphalaria glabrata, intermediate host for Schistosoma mansoni and compare these to known vertebrate NRs, with a view to assessing the snail's potential as a invertebrate model organism for endocrine function, both as a prospective new test organism and to elucidate the fundamental genetic and mechanistic causes of disease. For comparative purposes, the genome of a second gastropod, the owl limpet, Lottia gigantea was also investigated for nuclear receptors. Thirty-nine and thirty-three putative NRs were identified from the B. glabrata and L. gigantea genomes respectively, based on the presence of a conserved DNA-binding domain and/or ligand-binding domain. Nuclear receptor transcript expression was confirmed and sequences were subjected to a comparative phylogenetic analysis, which demonstrated that these molluscs have representatives of all the major NR subfamilies (1-6). Many of the identified NRs are conserved between vertebrates and invertebrates, however differences exist, most notably, the absence of receptors of Group 3C, which includes some of the vertebrate endocrine hormone targets. The mollusc genomes also contain NR homologues that are present in insects and nematodes but not in vertebrates, such as Group 1J (HR48/DAF12/HR96). The identification of many shared receptors between humans and molluscs indicates the potential for molluscs as model organisms; however the absence of several steroid hormone receptors indicates snail endocrine systems are fundamentally different.The National Centre for the Replacement, Refinement and Reduction of Animals in Research, Grant Ref:G0900802 to CSJ, LRN, SJ & EJR [www.nc3rs.org.uk]