Cosmological Solutions in String Theories

We obtain a large class of cosmological solutions in the toroidally-compactified low energy limits of string theories in $D$ dimensions. We consider solutions where a $p$-dimensional subset of the spatial coordinates, parameterising a flat space, a sphere, or an hyperboloid, describes the spatial sections of the physically-observed universe. The equations of motion reduce to Liouville or $SL(N+1,R)$ Toda equations, which are exactly solvable. We study some of the cases in detail, and find that under suitable conditions they can describe four-dimensional expanding universes. We discuss also how the solutions in $D$ dimensions behave upon oxidation back to the $D=10$ string theory or $D=11$ M-theory.Comment: Latex, 21 pages, a reference adjuste

Global overview of the management of acute cholecystitis during the COVID-19 pandemic (CHOLECOVID study)

Background: This study provides a global overview of the management of patients with acute cholecystitis during the initial phase of the COVID-19 pandemic. Methods: CHOLECOVID is an international, multicentre, observational comparative study of patients admitted to hospital with acute cholecystitis during the COVID-19 pandemic. Data on management were collected for a 2-month study interval coincident with the WHO declaration of the SARS-CoV-2 pandemic and compared with an equivalent pre-pandemic time interval. Mediation analysis examined the influence of SARS-COV-2 infection on 30-day mortality. Results: This study collected data on 9783 patients with acute cholecystitis admitted to 247 hospitals across the world. The pandemic was associated with reduced availability of surgical workforce and operating facilities globally, a significant shift to worse severity of disease, and increased use of conservative management. There was a reduction (both absolute and proportionate) in the number of patients undergoing cholecystectomy from 3095 patients (56.2 per cent) pre-pandemic to 1998 patients (46.2 per cent) during the pandemic but there was no difference in 30-day all-cause mortality after cholecystectomy comparing the pre-pandemic interval with the pandemic (13 patients (0.4 per cent) pre-pandemic to 13 patients (0.6 per cent) pandemic; P = 0.355). In mediation analysis, an admission with acute cholecystitis during the pandemic was associated with a non-significant increased risk of death (OR 1.29, 95 per cent c.i. 0.93 to 1.79, P = 0.121). Conclusion: CHOLECOVID provides a unique overview of the treatment of patients with cholecystitis across the globe during the first months of the SARS-CoV-2 pandemic. The study highlights the need for system resilience in retention of elective surgical activity. Cholecystectomy was associated with a low risk of mortality and deferral of treatment results in an increase in avoidable morbidity that represents the non-COVID cost of this pandemic

The Complexities of 'Home': Young people 'on the move' and state responses

'Home’ invokes ambiguous meanings for social policy; issues of safety within and beyond the home are recurring themes in criminological research and literature as well as policy and practice-based interventions. These concepts are further complicated when consideration is given to the experiences of young people who run away or go missing from the family home or alternative care. Drawing on an extensive body of research and rigorous analysis of ‘home’ in this context, the paper considers how gendered and classed youth identities affect responses and interventions. By ‘problematizing’ the universalised concept of home and the notion of ‘family’ that it implies, this paper makes an original contribution to theoretical aspects of running away and youth journeys, engaging with issues of space, place and relations of exclusion, subordination and domination in relation to family and state powers and responsibilities. Journeys from home are, interchangeably, escape routes and dangerous endeavours, but can also denote acts of resistance and quests for emancipation

Expert systems for site location decisions

Considers the scope for applying expert system techniques to assist in decisions regarding site location. Begins with a review of the theoretical literature and assesses the progress made in developing computer models. Its central theme is that the next step forward in this area is to develop expert systems. Addresses the question of the design of an expert system which would improve the decision-making process. Concludes that such a system is well within the scope of current technology, as long as developers can avoid being overambitious and as long as the end result is highly user friendly