Towards Understanding and Harnessing the Potential of Clause Learning

Efficient implementations of DPLL with the addition of clause learning are the fastest complete Boolean satisfiability solvers and can handle many significant real-world problems, such as verification, planning and design. Despite its importance, little is known of the ultimate strengths and limitations of the technique. This paper presents the first precise characterization of clause learning as a proof system (CL), and begins the task of understanding its power by relating it to the well-studied resolution proof system. In particular, we show that with a new learning scheme, CL can provide exponentially shorter proofs than many proper refinements of general resolution (RES) satisfying a natural property. These include regular and Davis-Putnam resolution, which are already known to be much stronger than ordinary DPLL. We also show that a slight variant of CL with unlimited restarts is as powerful as RES itself. Translating these analytical results to practice, however, presents a challenge because of the nondeterministic nature of clause learning algorithms. We propose a novel way of exploiting the underlying problem structure, in the form of a high level problem description such as a graph or PDDL specification, to guide clause learning algorithms toward faster solutions. We show that this leads to exponential speed-ups on grid and randomized pebbling problems, as well as substantial improvements on certain ordering formulas

Surgical interventions for anterior shoulder instability in rugby players: A systematic review

AIM: To systematically evaluate the evidence-based literature on surgical treatment interventions for elite rugby players with anterior shoulder instability. METHODS: We conducted a systematic review according to the PRISMA guidelines. A literature search was performed in PubMed, EMBASE and Google Scholar using the following search terms: rugby and shoulder in combination with instability or dislocation . All articles published from inception of the included data sources to January 1(st) 2014 that evaluated surgical treatment of elite rugby players with anterior shoulder instability were examined. RESULTS: Only five studies were found that met the eligibility criteria. A total of 379 shoulders in 376 elite rugby union and league players were included. All the studies were retrospective cohort or case series studies. The mean Coleman Methodological Score for the 5 studies was 47.4 (poor). Owing to heterogeneity amongst the studies, quantitative synthesis was not possible, however a detailed qualitative synthesis is reported. The overall recurrence rate of instability after surgery was 8.7%, and the mean return to competitive play, where reported, was 13 mo. CONCLUSION: Arthroscopic stabilization has been performed successfully in acute anterior instability and there is a preference for open Latarjet-type procedures when instability is associated with osseous defects

Outbreak of acute hepatitis C following the use of anti-hepatitis C virus--screened intravenous immunoglobulin therapy

BACKGROUND and AIMS: Hepatitis C virus (HCV) infection has been associated with intravenous (IV) immunoglobulin (Ig), and plasma donations used to prepare IV Ig are now screened to prevent transmission. Thirty-six patients from the United Kingdom received infusions from a batch of anti-HCV antibody-screened intravenous Ig (Gammagard; Baxter Healthcare Ltd., Thetford, Norfolk, England) that was associated with reports of acute hepatitis C outbreak in Europe. The aim of this study was to document the epidemiology of this outbreak. METHODS: Forty-six patients from the United Kingdom treated with Gammagard (34 exposed and 12 unexposed to the batch) returned epidemiological questionnaires. RESULTS: Eighty-two percent of the exposed patients (28 of 34) became positive for HCV RNA. Eighteen percent of the patients (6 of 34) who had infusions with this batch tested negative for HCV RNA, but 2 of the patients had abnormal liver function and subsequently seroconverted to anti-HCV antibody positive. Twenty-seven percent of the patients (9 of 34) developed jaundice, and 79% (27 of 34) had abnormal liver transferase levels. Virus isolates (n=21), including an isolate from the implicated batch, were genotype 1a and virtually identical by sequence analysis of the NS5 region, consistent with transmission from a single source. CONCLUSIONS: Hepatitis C infection can be transmitted by anti-HCV-screened IV Ig. Careful documentation of IV Ig batch numbers and regular biochemical monitoring is recommended for all IV Ig recipients

Revision shoulder hemiarthroplasty and total shoulder arthroplasty a systematic review and meta-analysis.

The number of shoulder replacements performed each year continues to increase, and the need for revision replacements has grown accordingly. The outcome of a revision replacement may influence which primary implant is selected and the timing of primary surgery, particularly in younger patients. The aim of this study was to establish the expected improvement in shoulder function and implant survival following revision of a hemiarthroplasty and revision of an anatomical total shoulder arthroplasty (TSA). A systematic review and meta-analysis were performed of all studies reporting shoulder scores or implant survival following revision hemiarthroplasty or revision TSA. MEDLINE, EMBASE, CENTRAL, The Cochrane Database of Systematic Reviews and National Joint Registry reports were searched. 15 studies were included, reporting on 593 revision anatomical shoulder replacements. There was large variation in the magnitude of improvement in shoulder scores following revision surgery. Over 80% of revision replacements last 5 years and over 70% last 10 years. There was no significant difference in shoulder scores or implant survival according to the type of primary implant. The belief that revision of a shoulder hemiarthroplasty may lead to improved outcomes compared to revision of a TSA is not supported by the current literature

Consent for orthopaedic trauma surgery during the COVID-19 pandemic

INTRODUCTION: The COVID-19 pandemic has brought a series of new challenges to the management of surgical patients. The consent process relies on a foundation of open and non-coerced discussion between clinician and patient, which includes all the potential risks of surgery. This must be updated to incorporate the additional risks of surgery during the pandemic including infection with the SARS-CoV-2 and increased risks of complications with the potential requirement for intensive care support. AIM: The aim of this multi-cycle quality improvement project was to ensure all patients were fully informed of the risks of developing COVID-19 and the possible need for intensive care unit (ICU) support. METHODS: We investigated the quality of the consent process for patients undergoing surgery for trauma at our major trauma centre. Our baseline data collection included a review of all orthopaedic trauma consent forms over a 4-week period in March 2020. We subsequently undertook three further Plan-Do-Study-Act (PDSA) cycles over separate 4-week periods. First, in June 2020, after education measures and presentation of baseline data, second in July 2020 after further education and regular digital reminders were sent to staff, and third in September 2021 after the implementation of an electronic consent form. RESULTS: At baseline, only 2.6% of consent forms mentioned the risk of COVID-19 and none mentioned the risk of requiring ITU support. Through three PDSA cycles this increased to 97% of cases where consent forms displayed the additional risks of COVID-19 and the potential need for ITU admission. CONCLUSION: Our quality improvement project improved the informed consent procedure at our trust. By incorporating these additional risks into the template of an electronic consent form, we hope to achieve sustained improvement in practice

Mapping the rotational diffusion of fluorophores in cells with time-resolved wide-field fluorescence anisotropy imaging

CLEO/EUROPE ; EQEC European Quantum Electronics Conference, Munich ICM, Germany, 22-27 June, 2003N

Anatomical shoulder replacements in young patients: A systematic review and meta-analysis

Introduction Increasing numbers of young patients receive shoulder replacements. Greater information on outcomes is needed to inform implant choice. The aim of this study was to investigate the survivorship and clinical effectiveness of hemiarthroplasty and anatomical total shoulder arthroplasty (TSA) in patients younger than 65 years. Method A systematic review was performed of MEDLINE, EMBASE, CENTRAL, The Cochrane Database of Systematic Reviews and National Joint Registry reports. The primary outcomes were implant survival and change in perioperative shoulder scores. Results Meta-analysis of implant survivorship was performed of six studies reporting on 416 patients. Implant survival was 86.1% (72.1,100) at 10 years for hemiarthroplasty and 82.3% (64.6,100) for TSA. 20 year survival was 80.0% for hemiarthroplasty (72.5,87.4) and 75.0% (56.9,93.1) for TSA. Ten studies were included in the meta-analysis of shoulder scores, multiple instruments were used. The standardised mean difference between pre-operative and post-operative shoulder scores was 2.15 (1.95, 2.35) for TSA at 4.2–4.9 years, and 2.72 (1.98,3.47) for hemiarthroplasty at 3.8–6 years. Conclusion Over 80% of shoulder replacements last more than 10 years, and 75% last more than 20 years. Significant improvements in shoulder scores are shown at all time points

Numerical loop quantum cosmology: an overview

A brief review of various numerical techniques used in loop quantum cosmology and results is presented. These include the way extensive numerical simulations shed insights on the resolution of classical singularities, resulting in the key prediction of the bounce at the Planck scale in different models, and the numerical methods used to analyze the properties of the quantum difference operator and the von Neumann stability issues. Using the quantization of a massless scalar field in an isotropic spacetime as a template, an attempt is made to highlight the complementarity of different methods to gain understanding of the new physics emerging from the quantum theory. Open directions which need to be explored with more refined numerical methods are discussed.Comment: 33 Pages, 4 figures. Invited contribution to appear in Classical and Quantum Gravity special issue on Non-Astrophysical Numerical Relativit

Cold saline irrigation of the renal pelvis during Radiofrequency Ablation of a central renal neoplasm: a case report

<p>Abstract</p> <p>Introduction</p> <p>Thermal destruction mediated by radiofrequency ablation (RFA) is gaining attention as an alternative treatment for patients with renal cell carcinoma (RCC), particularly in those who are not candidates for open surgery. Treatment of central tumours is occasionally associated with complications such as ureteric stricture, injury to the psoas muscle, haematuria and vascular laceration.</p> <p>Case presentation</p> <p>We have used infusion of cold saline during RFA, through a retrograde ureteric catheter with its tip in the renal pelvis, in a patient with a central renal tumour.</p> <p>Conclusion</p> <p>We believe this process to have successfully avoided the risk of thermal injury.</p