Distribution of Energy-Momentum in a Schwarzschild-Quintessence Space-time Geometry

An analysis of the energy-momentum localization for a four-dimensional\break Schwarzschild black hole surrounded by quintessence is presented in order to provide expressions for the distributions of energy and momentum. The calculations are performed by using the Landau-Lifshitz and Weinberg energy-momentum complexes. It is shown that all the momenta vanish, while the expression for the energy depends on the mass $M$ of the black hole, the state parameter $w_{q}$ and the normalization factor $c$. The special case of $w_{q}=-2/3$ is also studied, and two limiting cases are examined.Comment: 9 page

Energy Distribution for Non-commutative Radiating Schwarzschild Black Holes

The aim of this article is the calculation of the energy-momentum for a non-commutative radiating Schwarzschild black hole in order to obtain the expressions for energy. We make the calculations with the Einstein and M\oller prescriptions. We show that the expressions for energy in both the prescriptions depend on the mass $M$, $\theta$ parameter and radial coordinate. We make some comparisons between the results. Our results show that the Einstein prescription is a more powerful concept than the M\oller prescription.Comment: 5 pages and 6 figures. Revised version submitted in Int.J.Theor.Phys. after minor revisio

Reducing the environmental impact of surgery on a global scale: systematic review and co-prioritization with healthcare workers in 132 countries

Background Healthcare cannot achieve net-zero carbon without addressing operating theatres. The aim of this study was to prioritize feasible interventions to reduce the environmental impact of operating theatres. Methods This study adopted a four-phase Delphi consensus co-prioritization methodology. In phase 1, a systematic review of published interventions and global consultation of perioperative healthcare professionals were used to longlist interventions. In phase 2, iterative thematic analysis consolidated comparable interventions into a shortlist. In phase 3, the shortlist was co-prioritized based on patient and clinician views on acceptability, feasibility, and safety. In phase 4, ranked lists of interventions were presented by their relevance to high-income countries and low–middle-income countries. Results In phase 1, 43 interventions were identified, which had low uptake in practice according to 3042 professionals globally. In phase 2, a shortlist of 15 intervention domains was generated. In phase 3, interventions were deemed acceptable for more than 90 per cent of patients except for reducing general anaesthesia (84 per cent) and re-sterilization of ‘single-use’ consumables (86 per cent). In phase 4, the top three shortlisted interventions for high-income countries were: introducing recycling; reducing use of anaesthetic gases; and appropriate clinical waste processing. In phase 4, the top three shortlisted interventions for low–middle-income countries were: introducing reusable surgical devices; reducing use of consumables; and reducing the use of general anaesthesia. Conclusion This is a step toward environmentally sustainable operating environments with actionable interventions applicable to both high– and low–middle–income countries

Stochastic tracking and deposition of particles inside a complex geometry

The development of new medicines for inhalation requires a series of procedures including in-vitro tests using special testing devices, which simulate the human airways to assess the local deposition of drugs. Such tests require samples of the new drugs and the series of tests are costly and time-consuming. A numerical model for the two-phase flow inside the first chamber of one of these special devices, the Twin Impinger (TI), has been developed. Due to the effects of drag, gravity and virtual mass forces, computer-generated particles travel through the virtual TI, which was discretised using a structured mesh. An Eulerian model has been used to simulate the continuous phase and a Lagrangian stochastic eddy-interaction model (EIM) has been chosen to simulate the behaviour of the discrete phase. Aiming to reduce the uncertainty associated to turbulence modelling of the continuous phase in a complex flow, detailed experimental data has been taken for the mean and turbulent air velocity fields. These data have been obtained by the use of a 2D Laser Doppler Anemometer, employing the continuity concept to generate the third velocity component. The interaction between particles was not considered because it was supposed that the particles were already dispersed enough inside the TI. Finding the Eulerian control volume where the particle was after each Lagrangian time-step was attained in a circular search around the previous particle position, in preferential directions, for the closest mesh node. The Eulerian cell values for the mean and turbulent velocity fields were assumed everywhere except near the wall, where the gradients are larger, and corrections in both the flow model and the EIM were required. The interaction between the particles and the walls of the TI considered a coefficient of restitution depending on the angle of impact of the particles, which were considered adhered if their kinetic energy after impact was not sufficient to compensate the van der Waals forces between the wall and the particle. A simple procedure to compute the distance between the particle and the near-wall velocity led to preferential deposition in lines orientated along the mesh, and the formation of unphysical particle clusters. Major improvements to the global model performance were obtained by the use of near-wall corrections in the EIM and employing a more elaborate algorithm for the wall distance. However, these changes increased the computational cost of the numerical simulations