On the Search for the Synchrotron Cosmic Web

On the very largest of scales, the Universe is predicted to emit a faint radio signature as a result of ongoing structure formation: the so-called synchrotron cosmic web. This radio signature promises to shed light on vast, cluster-scale magnetic fields. In this work, we use both simulations to better understand the nature and distribution of this radio signal, and make several attempts towards practical detection using low frequency radio interferometers

The Mechanics of Order: An Inquiry into the Utopian Possibilities of the Free and Open Source Ecology

This is a study that concerns itself with two questions: how is order produced? and, is this order desirable? Contrary to many utopian methodologies that seek to elaborate 'what is not' but which 'ought to be', this is a study that seeks to contribute to a utopian mechanics by way of studying extant subterranean practices or ' minor traditions,' by studying elements of 'what is' that may also form something of what 'ought to be.' This study takes as its principal task to understand the production of order within a small free and open source project known as Compiz. It borrows from Michel Foucault, Gilles Deleuze and Felix Guattari to formulate the related concepts of the machine and the abstract machine in order to account for the ongoing production of order. These two concepts, following the lead of Bruno Latour, adhere to a 'flat social' ontology and bring forth the world of objects and space as being indispensible, alongside the members of Compiz, in accounting for the project's ordering. The study poses three primary machines of order: the Passport, the Exodus and the Module. The Passport regulates access within the virtual spaces of Compiz and produces a role known as the 'gatekeeper,' one who may exercise a power both vicarious and precarious. The machine of the Exodus makes the threat of desertion a real and ongoing possibility and in this establishes an 'imaginary counter' within the group, undermining the power of the gatekeeper and recasting him as a steward of the code, as 'maintainer.' The third machine, known as the Module, is designed to minimise the complexity of the project by way of the spatialisation and organisation of the code, but subsequently effects a concomitant spatialisation and organisation of developers and projects, coming in the end to shape the large scale order amongst free and open source projects. The study concludes by suggesting a 'present tense' and 'open ended' conception of utopia, in which both the machines of the Exodus and the Module - but not the Passport- would find themselves well placed

Improved Sensitivity for Space Domain Awareness Observations with the Murchison Widefield Array

Our previously reported survey of the Low Earth Orbit (LEO) environment using the Murchison Widefield Array (MWA) detected over 70 unique Resident Space Objects (RSOs) over multiple passes, from 20 hours of observations in passive radar mode. In this paper, we extend this work by demonstrating two methods that improve the detection sensitivity of the system. The first method, called shift-stacking, increases the statistical significance of faint RSO signals through the spatially coherent integration of the reflected signal along the RSO's trajectory across the sky. This method was tested on the observations used during our previous blind survey, and we obtained a $75\%$ increase in the total number of detections. The second method re-focuses the MWA to the near-field RSO's position (post-observation), by applying a complex phase correction to each visibility to account for the curved wave-front. The method was tested successfully on an MWA extended array observation of an ISS pass. However, the method is currently limited by signal de-coherence on the long-baselines (due to the hardware constraints of the current correlator). We discuss the sensitivity improvement for RSO detections we expect from the MWA Phase 3 correlator upgrade. We conclude the paper by briefly commenting on future dedicated Space Domain Awareness (SDA) systems that will incorporate MWA technologies.Comment: Accepted in Advances in Space Research. 16 pages, 10 figures, and 1 Tabl

Prognostic model to predict postoperative acute kidney injury in patients undergoing major gastrointestinal surgery based on a national prospective observational cohort study.

Background: Acute illness, existing co-morbidities and surgical stress response can all contribute to postoperative acute kidney injury (AKI) in patients undergoing major gastrointestinal surgery. The aim of this study was prospectively to develop a pragmatic prognostic model to stratify patients according to risk of developing AKI after major gastrointestinal surgery. Methods: This prospective multicentre cohort study included consecutive adults undergoing elective or emergency gastrointestinal resection, liver resection or stoma reversal in 2-week blocks over a continuous 3-month period. The primary outcome was the rate of AKI within 7 days of surgery. Bootstrap stability was used to select clinically plausible risk factors into the model. Internal model validation was carried out by bootstrap validation. Results: A total of 4544 patients were included across 173 centres in the UK and Ireland. The overall rate of AKI was 14·2 per cent (646 of 4544) and the 30-day mortality rate was 1·8 per cent (84 of 4544). Stage 1 AKI was significantly associated with 30-day mortality (unadjusted odds ratio 7·61, 95 per cent c.i. 4·49 to 12·90; P < 0·001), with increasing odds of death with each AKI stage. Six variables were selected for inclusion in the prognostic model: age, sex, ASA grade, preoperative estimated glomerular filtration rate, planned open surgery and preoperative use of either an angiotensin-converting enzyme inhibitor or an angiotensin receptor blocker. Internal validation demonstrated good model discrimination (c-statistic 0·65). Discussion: Following major gastrointestinal surgery, AKI occurred in one in seven patients. This preoperative prognostic model identified patients at high risk of postoperative AKI. Validation in an independent data set is required to ensure generalizability

Global patient outcomes after elective surgery: prospective cohort study in 27 low-, middle- and high-income countries.

BACKGROUND: As global initiatives increase patient access to surgical treatments, there remains a need to understand the adverse effects of surgery and define appropriate levels of perioperative care. METHODS: We designed a prospective international 7-day cohort study of outcomes following elective adult inpatient surgery in 27 countries. The primary outcome was in-hospital complications. Secondary outcomes were death following a complication (failure to rescue) and death in hospital. Process measures were admission to critical care immediately after surgery or to treat a complication and duration of hospital stay. A single definition of critical care was used for all countries. RESULTS: A total of 474 hospitals in 19 high-, 7 middle- and 1 low-income country were included in the primary analysis. Data included 44 814 patients with a median hospital stay of 4 (range 2-7) days. A total of 7508 patients (16.8%) developed one or more postoperative complication and 207 died (0.5%). The overall mortality among patients who developed complications was 2.8%. Mortality following complications ranged from 2.4% for pulmonary embolism to 43.9% for cardiac arrest. A total of 4360 (9.7%) patients were admitted to a critical care unit as routine immediately after surgery, of whom 2198 (50.4%) developed a complication, with 105 (2.4%) deaths. A total of 1233 patients (16.4%) were admitted to a critical care unit to treat complications, with 119 (9.7%) deaths. Despite lower baseline risk, outcomes were similar in low- and middle-income compared with high-income countries. CONCLUSIONS: Poor patient outcomes are common after inpatient surgery. Global initiatives to increase access to surgical treatments should also address the need for safe perioperative care. STUDY REGISTRATION: ISRCTN5181700

A922 Sequential measurement of 1 hour creatinine clearance (1-CRCL) in critically ill patients at risk of acute kidney injury (AKI)

Meeting abstrac

Evaluation of appendicitis risk prediction models in adults with suspected appendicitis

Background Appendicitis is the most common general surgical emergency worldwide, but its diagnosis remains challenging. The aim of this study was to determine whether existing risk prediction models can reliably identify patients presenting to hospital in the UK with acute right iliac fossa (RIF) pain who are at low risk of appendicitis. Methods A systematic search was completed to identify all existing appendicitis risk prediction models. Models were validated using UK data from an international prospective cohort study that captured consecutive patients aged 16–45 years presenting to hospital with acute RIF in March to June 2017. The main outcome was best achievable model specificity (proportion of patients who did not have appendicitis correctly classified as low risk) whilst maintaining a failure rate below 5 per cent (proportion of patients identified as low risk who actually had appendicitis). Results Some 5345 patients across 154 UK hospitals were identified, of which two‐thirds (3613 of 5345, 67·6 per cent) were women. Women were more than twice as likely to undergo surgery with removal of a histologically normal appendix (272 of 964, 28·2 per cent) than men (120 of 993, 12·1 per cent) (relative risk 2·33, 95 per cent c.i. 1·92 to 2·84; P < 0·001). Of 15 validated risk prediction models, the Adult Appendicitis Score performed best (cut‐off score 8 or less, specificity 63·1 per cent, failure rate 3·7 per cent). The Appendicitis Inflammatory Response Score performed best for men (cut‐off score 2 or less, specificity 24·7 per cent, failure rate 2·4 per cent). Conclusion Women in the UK had a disproportionate risk of admission without surgical intervention and had high rates of normal appendicectomy. Risk prediction models to support shared decision‐making by identifying adults in the UK at low risk of appendicitis were identified

The Mechanics of Order: An Inquiry into the Utopian Possibilities of the Free and Open Source Ecology

This is a study that concerns itself with two questions: how is order produced? and, is this order desirable? Contrary to many utopian methodologies that seek to elaborate 'what is not' but which 'ought to be', this is a study that seeks to contribute to a utopian mechanics by way of studying extant subterranean practices or ' minor traditions,' by studying elements of 'what is' that may also form something of what 'ought to be.' This study takes as its principal task to understand the production of order within a small free and open source project known as Compiz. It borrows from Michel Foucault, Gilles Deleuze and Felix Guattari to formulate the related concepts of the machine and the abstract machine in order to account for the ongoing production of order. These two concepts, following the lead of Bruno Latour, adhere to a 'flat social' ontology and bring forth the world of objects and space as being indispensible, alongside the members of Compiz, in accounting for the project's ordering. The study poses three primary machines of order: the Passport, the Exodus and the Module. The Passport regulates access within the virtual spaces of Compiz and produces a role known as the 'gatekeeper,' one who may exercise a power both vicarious and precarious. The machine of the Exodus makes the threat of desertion a real and ongoing possibility and in this establishes an 'imaginary counter' within the group, undermining the power of the gatekeeper and recasting him as a steward of the code, as 'maintainer.' The third machine, known as the Module, is designed to minimise the complexity of the project by way of the spatialisation and organisation of the code, but subsequently effects a concomitant spatialisation and organisation of developers and projects, coming in the end to shape the large scale order amongst free and open source projects. The study concludes by suggesting a 'present tense' and 'open ended' conception of utopia, in which both the machines of the Exodus and the Module - but not the Passport- would find themselves well placed

The Mechanics of Order: An Inquiry into the Utopian Possibilities of the Free and Open Source Ecology

This is a study that concerns itself with two questions: how is order produced? and, is this order desirable? Contrary to many utopian methodologies that seek to elaborate 'what is not' but which 'ought to be', this is a study that seeks to contribute to a utopian mechanics by way of studying extant subterranean practices or ' minor traditions,' by studying elements of 'what is' that may also form something of what 'ought to be.'  This study takes as its principal task to understand the production of order within a small free and open source project known as Compiz. It borrows from Michel Foucault, Gilles Deleuze and Felix Guattari to formulate the related concepts of the machine and the abstract machine in order to account for the ongoing production of order. These two concepts, following the lead of Bruno Latour, adhere to a 'flat social' ontology and bring forth the world of objects and space as being indispensible, alongside the members of Compiz, in accounting for the project's ordering. The study poses three primary machines of order: the Passport, the Exodus and the Module. The Passport regulates access within the virtual spaces of Compiz and produces a role known as the 'gatekeeper,' one who may exercise a power both vicarious and precarious. The machine of the Exodus makes the threat of desertion a real and ongoing possibility and in this establishes an 'imaginary counter' within the group, undermining the power of the gatekeeper and recasting him as a steward of the code, as 'maintainer.' The third machine, known as the Module, is designed to minimise the complexity of the project by way of the spatialisation and organisation of the code, but subsequently effects a concomitant spatialisation and organisation of developers and projects, coming in the end to shape the large scale order amongst free and open source projects. The study concludes by suggesting a 'present tense' and 'open ended' conception of utopia, in which both the machines of the Exodus and the Module - but not the Passport- would find themselves well placed.</p