29 research outputs found
Purely Magnetic Spacetimes
Purely magnetic spacetimes, in which the Riemann tensor satisfies
for some unit timelike vector , are studied. The
algebraic consequences for the Weyl and Ricci tensors are examined in detail
and consideration given to the uniqueness of . Some remarks concerning the
nature of the congruence associated with are made.Comment: 12 pages, standard latex. Submitted to Classical and Quantum Gravity
Hallucinations in Large Multilingual Translation Models
Large-scale multilingual machine translation systems have demonstrated
remarkable ability to translate directly between numerous languages, making
them increasingly appealing for real-world applications. However, when deployed
in the wild, these models may generate hallucinated translations which have the
potential to severely undermine user trust and raise safety concerns. Existing
research on hallucinations has primarily focused on small bilingual models
trained on high-resource languages, leaving a gap in our understanding of
hallucinations in massively multilingual models across diverse translation
scenarios. In this work, we fill this gap by conducting a comprehensive
analysis on both the M2M family of conventional neural machine translation
models and ChatGPT, a general-purpose large language model~(LLM) that can be
prompted for translation. Our investigation covers a broad spectrum of
conditions, spanning over 100 translation directions across various resource
levels and going beyond English-centric language pairs. We provide key insights
regarding the prevalence, properties, and mitigation of hallucinations, paving
the way towards more responsible and reliable machine translation systems
Geometric Interpretation of the Mixed Invariants of the Riemann Spinor
Mixed invariants are used to classify the Riemann spinor in the case of
Einstein-Maxwell fields and perfect fluids. In the Einstein-Maxwell case these
mixed invariants provide information as to the relative orientation of the
gravitational and electromagnetic principal null directions. Consideration of
the perfect fluid case leads to some results about the behaviour of the
Bel-Robinson tensor regarded as a quartic form on unit timelike vectors.Comment: 31 pages, AMS-LaTe
Overview of BioCreative II gene mention recognition.
Nineteen teams presented results for the Gene Mention Task at the BioCreative II Workshop. In this task participants designed systems to identify substrings in sentences corresponding to gene name mentions. A variety of different methods were used and the results varied with a highest achieved F1 score of 0.8721. Here we present brief descriptions of all the methods used and a statistical analysis of the results. We also demonstrate that, by combining the results from all submissions, an F score of 0.9066 is feasible, and furthermore that the best result makes use of the lowest scoring submissions
The acceptability of conducting data linkage research without obtaining consent: lay peopleâs views and justifications
Outcomes of obstructed abdominal wall hernia: results from the UK national small bowel obstruction audit
Background:
Abdominal wall hernia is a common surgical condition. Patients may present in an emergency with bowel obstruction, incarceration or strangulation. Small bowel obstruction (SBO) is a serious surgical condition associated with significant morbidity. The aim of this study was to describe current management and outcomes of patients with obstructed hernia in the UK as identified in the National Audit of Small Bowel Obstruction (NASBO).
Methods:
NASBO collated data on adults treated for SBO at 131 UK hospitals between January and March 2017. Those with obstruction due to abdominal wall hernia were included in this study. Demographics, co-morbidity, imaging, operative treatment, and in-hospital outcomes were recorded. Modelling for factors associated with mortality and complications was undertaken using Cox proportional hazards and multivariable regression modelling.
Results:
NASBO included 2341 patients, of whom 415 (17·7 per cent) had SBO due to hernia. Surgery was performed in 312 (75·2 per cent) of the 415 patients; small bowel resection was required in 198 (63·5 per cent) of these operations. Non-operative management was reported in 35 (54 per cent) of 65 patients with a parastomal hernia and in 34 (32·1 per cent) of 106 patients with an incisional hernia. The in-hospital mortality rate was 9·4 per cent (39 of 415), and was highest in patients with a groin hernia (11·1 per cent, 17 of 153). Complications were common, including lower respiratory tract infection in 16·3 per cent of patients with a groin hernia. Increased age was associated with an increased risk of death (hazard ratio 1·05, 95 per cent c.i. 1·01 to 1·10; P = 0·009) and complications (odds ratio 1·05, 95 per cent c.i. 1·02 to 1·09; P = 0·001).
Conclusion:
NASBO has highlighted poor outcomes for patients with SBO due to hernia, highlighting the need for quality improvement initiatives in this group
National prospective cohort study of the burden of acute small bowel obstruction
Background
Small bowel obstruction is a common surgical emergency, and is associated with high levels of morbidity and mortality across the world. The literature provides little information on the conservatively managed group. The aim of this study was to describe the burden of small bowel obstruction in the UK.
Methods
This prospective cohort study was conducted in 131 acute hospitals in the UK between January and April 2017, delivered by trainee research collaboratives. Adult patients with a diagnosis of mechanical small bowel obstruction were included. The primary outcome was inâhospital mortality. Secondary outcomes included complications, unplanned intensive care admission and readmission within 30 days of discharge. Practice measures, including use of radiological investigations, water soluble contrast, operative and nutritional interventions, were collected.
Results
Of 2341 patients identified, 693 (29·6 per cent) underwent immediate surgery (within 24 h of admission), 500 (21·4 per cent) had delayed surgery after initial conservative management, and 1148 (49·0 per cent) were managed nonâoperatively. The mortality rate was 6·6 per cent (6·4 per cent for nonâoperative management, 6·8 per cent for immediate surgery, 6·8 per cent for delayed surgery; P = 0·911). The major complication rate was 14·4 per cent overall, affecting 19·0 per cent in the immediate surgery, 23·6 per cent in the delayed surgery and 7·7 per cent in the nonâoperative management groups (P < 0·001). Cox regression found hernia or malignant aetiology and malnutrition to be associated with higher rates of death. Malignant aetiology, operative intervention, acute kidney injury and malnutrition were associated with increased risk of major complication.
Conclusion
Small bowel obstruction represents a significant healthcare burden. Patientâlevel factors such as timing of surgery, acute kidney injury and nutritional status are factors that might be modified to improve outcomes
Outcomes of obstructed abdominal wall hernia: results from the UK national small bowel obstruction audit
Background
Abdominal wall hernia is a common surgical condition. Patients may present in an emergency with bowel obstruction, incarceration or strangulation. Small bowel obstruction (SBO) is a serious surgical condition associated with significant morbidity. The aim of this study was to describe current management and outcomes of patients with obstructed hernia in the UK as identified in the National Audit of Small Bowel Obstruction (NASBO).
Methods
NASBO collated data on adults treated for SBO at 131 UK hospitals between January and March 2017. Those with obstruction due to abdominal wall hernia were included in this study. Demographics, coâmorbidity, imaging, operative treatment, and inâhospital outcomes were recorded. Modelling for factors associated with mortality and complications was undertaken using Cox proportional hazards and multivariable regression modelling.
Results
NASBO included 2341 patients, of whom 415 (17·7 per cent) had SBO due to hernia. Surgery was performed in 312 (75·2 per cent) of the 415 patients; small bowel resection was required in 198 (63·5 per cent) of these operations. Nonâoperative management was reported in 35 (54 per cent) of 65 patients with a parastomal hernia and in 34 (32·1 per cent) of 106 patients with an incisional hernia. The inâhospital mortality rate was 9·4 per cent (39 of 415), and was highest in patients with a groin hernia (11·1 per cent, 17 of 153). Complications were common, including lower respiratory tract infection in 16·3 per cent of patients with a groin hernia. Increased age was associated with an increased risk of death (hazard ratio 1·05, 95 per cent c.i. 1·01 to 1·10; P = 0·009) and complications (odds ratio 1·05, 95 per cent c.i. 1·02 to 1·09; P = 0·001).
Conclusion
NASBO has highlighted poor outcomes for patients with SBO due to hernia, highlighting the need for quality improvement initiatives in this group
Outcomes following small bowel obstruction due to malignancy in the national audit of small bowel obstruction
Introduction
Patients with cancer who develop small bowel obstruction are at high risk of malnutrition and morbidity following compromise of gastrointestinal tract continuity. This study aimed to characterise current management and outcomes following malignant small bowel obstruction.
Methods
A prospective, multicentre cohort study of patients with small bowel obstruction who presented to UK hospitals between 16th January and 13th March 2017. Patients who presented with small bowel obstruction due to primary tumours of the intestine (excluding left-sided colonic tumours) or disseminated intra-abdominal malignancy were included. Outcomes included 30-day mortality and in-hospital complications. Cox-proportional hazards models were used to generate adjusted effects estimates, which are presented as hazard ratios (HR) alongside the corresponding 95% confidence interval (95% CI). The threshold for statistical significance was set at the level of PâŻâ€âŻ0.05 a-priori.
Results
205 patients with malignant small bowel obstruction presented to emergency surgery services during the study period. Of these patients, 50 had obstruction due to right sided colon cancer, 143 due to disseminated intraabdominal malignancy, 10 had primary tumours of the small bowel and 2 patients had gastrointestinal stromal tumours. In total 100 out of 205 patients underwent a surgical intervention for obstruction. 30-day in-hospital mortality rate was 11.3% for those with primary tumours and 19.6% for those with disseminated malignancy. Severe risk of malnutrition was an independent predictor for poor mortality in this cohort (adjusted HR 16.18, 95% CI 1.86 to 140.84, pâŻ=âŻ0.012). Patients with right-sided colon cancer had high rates of morbidity.
Conclusions
Mortality rates were high in patients with disseminated malignancy and in those with right sided colon cancer. Further research should identify optimal management strategy to reduce morbidity for these patient groups