Ground state superconducting phase fluctuations as a precursor for strong critical fluctuations in high-T_c superconductors

We analyse the reversible magnetisation and heat capacity of YBa_2Cu_3O_7-δ in the "vortex liquid" state and find that both properties are reasonably well described by the 3D XY critical-fluctuation model. The free-energy density in the "vortex liquid" state has a particularly simple form over a wide range of fields (H) and temperatures (T). This leads us to a picture in which the presence of critical fluctuations in high-T_c superconductors is directly linked to the remarkably small number of overlapping Cooper pairs at T=0 and H=0 rather than low dimensionality or high temperatures

Formative Evaluation of a Hepatitis C Virus Computer Assisted Instruction Tool or Communities of African Descent

Hepatitis C Virus (HCV) has become increasingly prevalent within traditionally undeserved communities. The paper describes the formative evaluation of a HCV Computer Assisted Instruction (CAI) tool. Specific aims are to describe the feasibility of a CAI tool with a high-risk population, and the use of Nigrescence Theory to develop targeted messages. Three participants, recruited at an all-male substance abuse halfway house, reviewed the CAI in a mini-focus group. A Health History/HCV Knowledge Questionnaire, The Cross Racial Identity Scale and a focus group question route were used to collect qualitative and quantitative data. The analysis plan utilized descriptive statistics, content analysis and profile analysis. Results suggested that the CAI was acceptable to this segment of the population, and Nigrescence Theory provided a context for targeting messages to differing segments of the target group. Recommendations are offered to health promotion programs targeting people of African descent

The effect of medications which cause inflammation of the gastro-oesophageal tract on cancer risk : a nested case–control study of routine Scottish data

Peer reviewedPostprin

Ground state superconducting phase fluctuations as a precursor for strong critical fluctuations in high-T_c superconductors

We analyse the reversible magnetisation and heat capacity of YBa_2Cu_3O_7-δ in the "vortex liquid" state and find that both properties are reasonably well described by the 3D XY critical-fluctuation model. The free-energy density in the "vortex liquid" state has a particularly simple form over a wide range of fields (H) and temperatures (T). This leads us to a picture in which the presence of critical fluctuations in high-T_c superconductors is directly linked to the remarkably small number of overlapping Cooper pairs at T=0 and H=0 rather than low dimensionality or high temperatures

Technologies for the diagnosis of angle closure glaucoma (ACE): protocol of a prospective, multicentre, cross-sectional diagnostic study

INTRODUCTION: Angle-closure is responsible for half of all glaucoma blindness globally. Patients with suspected glaucoma require assessment of the drainage angle by an experienced clinician. The goal of this study is to evaluate the diagnostic performance and cost-effectiveness of two non-contact tests, anterior segment OCT (Optical Coherence Tomography) (AS-OCT) and limbal anterior chamber depth for patients referred to hospital with suspected angle closure compared with gonioscopy by ophthalmologist. METHODS AND ANALYSIS: Study design: prospective, multicentre, cross-sectional diagnostic accuracy study. INCLUSION CRITERIA: adults referred from community optometry to hospital with suspected angle closure. PRIMARY OUTCOME: Sensitivity and specificity. SECONDARY OUTCOMES: Positive/negative likelihood ratios, concordance, cost-effectiveness, proportion of patients requiring subsequent clinical assessment by ophthalmologist. SAMPLE SIZE: 600 individuals who have been referred with suspected angle closure from primary care (community optometry). We will have a 95% probability of detecting the true sensitivity of either test to within ±3.5% based on a sensitivity of 90%. The study would also have a 95% probability of detecting the true specificity of either test to within ±5%, assuming a specificity of 75%. ETHICS AND DISSEMINATION: Ethical Review Board approval was obtained. REC reference: 22/LO/0885. Our findings will be disseminated to those involved in eye care services. We will have a knowledge exchange event at the end of the study, published via the Health Technology Assessment web page and in specialist journals. The results will be presented at professional conferences and directly to patients via patient group meetings and the Glaucoma UK charity. TRIAL REGISTRATION NUMBER: ISRCTN15115867

The role of 5α‐reductase inhibitors in gastro‐oesophageal cancer risk : A nested case‐control study

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Development of an Ion Thruster and Power Processor for New Millennium's Deep Space 1 Mission

The NASA Solar Electric Propulsion Technology Applications Readiness Program (NSTAR) will provide a single-string primary propulsion system to NASA's New Millennium Deep Space 1 Mission which will perform comet and asteroid flybys in the years 1999 and 2000. The propulsion system includes a 30-cm diameter ion thruster, a xenon feed system, a power processing unit, and a digital control and interface unit. A total of four engineering model ion thrusters, three breadboard power processors, and a controller have been built, integrated, and tested. An extensive set of development tests has been completed along with thruster design verification tests of 2000 h and 1000 h. An 8000 h Life Demonstration Test is ongoing and has successfully demonstrated more than 6000 h of operation. In situ measurements of accelerator grid wear are consistent with grid lifetimes well in excess of the 12,000 h qualification test requirement. Flight hardware is now being assembled in preparation for integration, functional, and acceptance tests

Medications that relax the lower oesophageal sphincter and risk of oesophageal cancer : An analysis of two independent population-based databases

Acknowledgements We acknowledge collaboration with the Research Applications and Data Management Team lead by Ms Katie Wilde, University of Aberdeen in conducting our study. This research has been conducted using the UK Bio-bank Resource under application number 34374.Peer reviewedPostprin

Characterisation of the mechanical failure and fracture mechanisms of single grain Y–Ba–Cu–O bulk superconductors

Abstract: The widespread use of melt processed, single grain (RE)–Ba–Cu–O bulk superconductors [(RE)BCO], where RE = Y, Gd or Sm, is limited predominantly by the poor mechanical properties of these inherently brittle, ceramic-like materials. The high density of flaws, such as cracks and voids, within the single grain microstructure leads directly to a low fracture toughness. As a result, the Lorentz forces, generated when these materials carry current in the presence of a large magnetic field, create stresses sufficiently large to cause brittle failure. The addition of Ba–Cu–O (liquid phase) and Ag to the precursor composition prior to melt-growth has been demonstrated to be effective in improving the mechanical properties of these technologically important materials. In this work, we characterise the mechanical failure of single grain YBCO bulk superconductors in terms of a Weibull statistical distribution. In addition, differences in fracture mechanisms have been studied to provide a better understanding of how the provision of additional liquid phase and silver produces YBCO single grains with better resulting mechanical properties and how these can be improved further