Einstein--Maxwell--Dilaton metrics from three--dimensional Einstein--Weyl structures

A class of time dependent solutions to $(3+1)$ Einstein--Maxwell-dilaton theory with attractive electric force is found from Einstein--Weyl structures in (2+1) dimensions corresponding to dispersionless Kadomtsev--Petviashvili and $SU(\infty)$ Toda equations. These solutions are obtained from time--like Kaluza--Klein reductions of $(3+2)$ solitons.Comment: 12 pages, to be published in Class.Quantum Gra

Planck Scale Physics of the Single Particle Schr\"{o}dinger Equation with Gravitational Self-Interaction

We consider the modification of a single particle Schr\"{o}dinger equation by the inclusion of an additional gravitational self-potential term which follows from the prescription that the' mass-density'that enters this term is given by $m |\psi (\vec {r},t)|^2$, where $\psi (\vec {r}, t)$ is the wavefunction and $m$ is the mass of the particle. This leads to a nonlinear equation, the ' Newton Schrodinger' equation, which has been found to possess stationary self-bound solutions, whose energy can be determined exactly using an asymptotic method. We find that such a particle strongly violates superposition and becomes a black hole as its mass approaches the Planck mass.Comment: 16 pages, Revtex, No figure, Submitted to Physics Letters

Oscillatons revisited

In this paper, we study some interesting properties of a spherically symmetric oscillating soliton star made of a real time-dependent scalar field which is called an oscillaton. The known final configuration of an oscillaton consists of a stationary stage in which the scalar field and the metric coefficients oscillate in time if the scalar potential is quadratic. The differential equations that arise in the simplest approximation, that of coherent scalar oscillations, are presented for a quadratic scalar potential. This allows us to take a closer look at the interesting properties of these oscillating objects. The leading terms of the solutions considering a quartic and a cosh scalar potentials are worked in the so called stationary limit procedure. This procedure reveals the form in which oscillatons and boson stars may be related and useful information about oscillatons is obtained from the known results of boson stars. Oscillatons could compete with boson stars as interesting astrophysical objects, since they would be predicted by scalar field dark matter models.Comment: 10 pages REVTeX, 10 eps figures. Updated files to match version published in Classical and Quantum Gravit

Heritage designation and scale: a World Heritage case study of the Ningaloo Coast

© 2015 Tod Jones, Roy Jones and Michael Hughes As heritage research has engaged with a greater plurality of heritage practices, scale has emerged as an important concept in Heritage Studies, albeit relatively narrowly defined as hierarchical levels (household, local, national, etcetera). This paper argues for a definition of scale in heritage research that incorporates size (geographical scale), level (vertical scale) and relation (an understanding that scale is constituted through dynamic relationships in specific contexts). The paper utilises this definition of scale to analyse heritage designation first through consideration of changing World Heritage processes, and then through a case study of the world heritage designation of the Ningaloo Coast region in Western Australia. Three key findings are: both scale and heritage gain appeal because they are abstractions, and gain definition through the spatial politics of interrelationships within specific situations; the spatial politics of heritage designation comes into focus through attention to those configurations of size, level and relation that are invoked and enabled in heritage processes; and researchers choice to analyse or ignore particular scales and scalar politics are political decisions. Utilising scale as size, level and relation enables analyses that move beyond heritage to the spatial politics through which all heritage is constituted

On the solutions of the second heavenly and Pavlov equations

We have recently solved the inverse scattering problem for one parameter families of vector fields, and used this result to construct the formal solution of the Cauchy problem for a class of integrable nonlinear partial differential equations connected with the commutation of multidimensional vector fields, like the heavenly equation of Plebanski, the dispersionless Kadomtsev - Petviashvili (dKP) equation and the two-dimensional dispersionless Toda (2ddT) equation, as well as with the commutation of one dimensional vector fields, like the Pavlov equation. We also showed that the associated Riemann-Hilbert inverse problems are powerfull tools to establish if the solutions of the Cauchy problem break at finite time,to construct their longtime behaviour and characterize classes of implicit solutions. In this paper, using the above theory, we concentrate on the heavenly and Pavlov equations, i) establishing that their localized solutions evolve without breaking, unlike the cases of dKP and 2ddT; ii) constructing the longtime behaviour of the solutions of their Cauchy problems; iii) characterizing a distinguished class of implicit solutions of the heavenly equation.Comment: 16 pages. Submitted to the: Special issue on nonlinearity and geometry: connections with integrability of J. Phys. A: Math. and Theor., for the conference: Second Workshop on Nonlinearity and Geometry. Darboux day

X-Ray and Radio Monitoring of the Neutron Star Low-mass X-Ray Binary 1A 1744-361: Quasiperiodic Oscillations, Transient Ejections, and a Disk Atmosphere

We report on X-ray (NICER/NuSTAR/MAXI/Swift) and radio (MeerKAT) timing and spectroscopic analysis from a 3 month monitoring campaign in 2022 of a high-intensity outburst of the dipping neutron star low-mass X-ray binary 1A 1744−361. The 0.5–6.8 keV NICER X-ray hardness–intensity and color–color diagrams of the observations throughout the outburst suggest that 1A 1744−361 spent most of its outburst in an atoll-state, but we show that the source exhibited Z-state-like properties at the peak of the outburst, similar to a small sample of other atoll-state sources. A timing analysis with NICER data revealed several instances of an ≈8 Hz quasiperiodic oscillation (QPO; fractional rms amplitudes of ∼5%) around the peak of the outburst, the first from this source, which we connect to the normal branch QPOs seen in the Z-state. Our observations of 1A 1744−361 are fully consistent with the idea of the mass accretion rate being the main distinguishing parameter between atoll- and Z-states. Radio monitoring data by MeerKAT suggests that the source was at its radio-brightest during the outburst peak, and that the source transitioned from the “island” spectral state to the “banana” state within ∼3 days of the outburst onset, launching transient jet ejecta. The observations present the strongest evidence for radio flaring, including jet ejecta, during the island-to-banana spectral state transition at low accretion rates (atoll-state). The source also exhibited Fe xxv, Fe xxvi Kα, and Kβ X-ray absorption lines, whose origins likely lie in an accretion disk atmosphere

Configuration of vascular services: a multiple methods research programme

Background Vascular services is changing rapidly, having emerged as a new specialty with its own training and specialised techniques. This has resulted in the need for reconfiguration of services to provide adequate specialist provision and accessible and equitable services. Objectives To identify the effects of service configuration on practice, resource use and outcomes. To model potential changes in configuration. To identify and/or develop electronic data collection tools for collecting patient-reported outcome measures and other clinical information. To evaluate patient preferences for aspects of services other than health-related quality of life. Design This was a multiple methods study comprising multiple systematic literature reviews; the development of a new outcome measure for users of vascular services (the electronic Personal Assessment Questionnaire – Vascular) based on the reviews, qualitative studies and psychometric evaluation; a trade-off exercise to measure process utilities; Hospital Episode Statistics analysis; and the development of individual disease models and a metamodel of service configuration. Setting Specialist vascular inpatient services in England. Data sources Modelling and Hospital Episode Statistics analysis for all vascular inpatients in England from 2006 to 2018. Qualitative studies and electronic Personal Assessment Questionnaire – Vascular evaluation with vascular patients from the Sheffield area. The trade-off studies were based on a societal sample from across England. Interventions The data analysis, preference studies and modelling explored the effect of different potential arrangements for service provision on the resource use, workload and outcomes for all interventions in the three main areas of inpatient vascular treatment: peripheral arterial disease, abdominal aortic aneurysm and carotid artery disease. The electronic Personal Assessment Questionnaire – Vascular was evaluated as a potential tool for clinical data collection and outcome monitoring. Main outcome measures Systematic reviews assessed quality and psychometric properties of published outcome measures for vascular disease and the relationship between volume and outcome in vascular services. The electronic Personal Assessment Questionnaire – Vascular development considered face and construct validity, test–retest reliability and responsiveness. Models were validated using case studies from previous reconfigurations and comparisons with Hospital Episode Statistics data. Preference studies resulted in estimates of process utilities for aneurysm treatment and for travelling distances to access services. Results Systematic reviews provided evidence of an association between increasing volume of activity and improved outcomes for peripheral arterial disease, abdominal aortic aneurysm and carotid artery disease. Reviews of existing patient-reported outcome measures did not identify suitable condition-specific tools for incorporation in the electronic Personal Assessment Questionnaire – Vascular. Reviews of qualitative evidence, primary qualitative studies and a Delphi exercise identified the issues to be incorporated into the electronic Personal Assessment Questionnaire – Vascular, resulting in a questionnaire with one generic and three disease-specific domains. After initial item reduction, the final version has 55 items in eight scales and has acceptable psychometric properties. The preference studies showed strong preference for endovascular abdominal aortic aneurysm treatment (willingness to trade up to 0.135 quality-adjusted life-years) and for local services (up to 0.631 quality-adjusted life-years). A simulation model with a web-based interface was developed, incorporating disease-specific models for abdominal aortic aneurysm, peripheral arterial disease and carotid artery disease. This predicts the effects of specified reconfigurations on workload, resource use, outcomes and cost-effectiveness. Initial exploration suggested that further reconfiguration of services in England to accomplish high-volume centres would result in improved outcomes, within the bounds of cost-effectiveness usually considered acceptable in the NHS. Limitations The major source of evidence to populate the models was Hospital Episode Statistics data, which have limitations owing to the complexity of the data, deficiencies in the coding systems and variations in coding practice. The studies were not able to address all of the potential barriers to change where vascular services are not compliant with current NHS recommendations. Conclusions There is evidence of potential for improvement in the clinical effectiveness and cost-effectiveness of vascular services through further centralisation of sites where major vascular procedures are undertaken. Preferences for local services are strong, and this may be addressed through more integrated services, with a range of services being provided more locally. The use of a web-based tool for the collection of clinical data and patient-reported outcome measures is feasible and can provide outcome data for clinical use and service evaluation. Future work Further evaluation of the economic models in real-world situations where local vascular service reconfiguration is under consideration and of the barriers to change where vascular services do not meet NHS recommendations for service configuration is needed. Further work on the electronic Personal Assessment Questionnaire – Vascular is required to assess its acceptability and usefulness in clinical practice and to develop appropriate report formats for clinical use and service evaluation. Further studies to assess the implications of including non-health-related preferences for care processes, and location of services, in calculations of cost-effectiveness are required. Study registration This study is registered as PROSPERO CRD42016042570, CRD42016042573, CRD42016042574, CRD42016042576, CRD42016042575, CRD42014014850, CRD42015023877 and CRD42015024820. Funding This project was funded by the National Institute for Health Research (NIHR) Programme Grants for Applied Research programme and will be published in full in Programme Grants for Applied Research; Vol. 9, No. 5. See the NIHR Journals Library website for further project information

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