Optimization of massive connections in 5G networks for IoT

The expected traffic demands for the coming years requires a major technology development. Indeed, from 2017 to 2022, the global annual traffic growth is estimated to reach 220%. This annual growth leads in turn to an increase in the number of users connected to IP networks, going from 2.4 to 3.6 devices connected per person. Currently, 4G networks are capable of handling this load, but the irruption of the 5G breakthroughs, expected to be at full operation by 2020, is visible. However, 5G technologies may come along with a considerable power consumption if they are not devised properly. As a consequence, a key issue in the developing of these networks is to make them energetically sustainable. In this work, a preliminary study of the optimization of various aspects of the 5G system is presented. It addresses the configuration of the different basic parameters of the system and optimizes the power transmitted by the base stations to obtain simultaneous improvements in system capacity and its power consumption for a massive connections scenario. To the best of our knowledge, this is the very first time this type of 5G scenario is optimized with these two performance criteria.Universidad de Málaga. Campus de Excelencia Internacional Andalucía Tech

Ultra-Low-loss Reconfigurable Phase-shifting Metasurface in V band:A Multi-objective Optimization Approach

Future generations of satellite and mobile communications at mm-wave frequencies require the use of low-loss and wideband phase-shifting components. Pixelated metasurfaces provide large design versatility and constitute an attractive solution for wave manipulation, such as shifting the phase of an incident wave. However, their design often implies the simultaneous tuning of a large number of geometrical parameters. This article employs an enhanced multi-objective optimization algorithm to design a dynamically reconfigurable metasurface providing ultra-low losses and linear phase response. The presented methodology can be easily employed for different objective functions or technologies, constituting a versatile design strategy for electromechanically reconfigurable devices based on pixelated metasurfaces. A prototype is fabricated based on the optimization outcome, achieving a phase shifter capable of providing a continuous phase shift up to 180∘ between 50 and 65 GHz. A piezo-electric actuator is used to dynamically adjust the phase shift with respect to the position of a metallic ground plane placed in front of the metasurface. A linear evolution of the phase w.r.t. the ground plane displacement is obtained while maintaining the losses around 1 dB for the whole frequency range

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

Abstract 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

On the Rigorous Design of Graphene-based Periodic Structures Exploiting the Fundamental Resonances

The electromagnetic response of graphene plasmonic scatterers is realized in the present work by exploiting their natural modes. Initially, a formulation to extract the latter is presented, where the planar material is modeled as an equivalent surface current. Then, a simple disk scatterer is considered and the fundamental modes are evaluated to distinguish them between edge and bulk ones, taking into account the field distribution. Moreover, the resonance frequencies for the case of incident plane-wave scattering are connected to the characteristics of the fundamental modes. Finally, a periodic array of graphene scatterers is investigated to highlight the additional plasmonic coupling resonances, corresponding to natural modes of different attributes.</p

Effects of pre-operative isolation on postoperative pulmonary complications after elective surgery: an international prospective cohort study an international prospective cohort study

We aimed to determine the impact of pre-operative isolation on postoperative pulmonary complications after elective surgery during the global SARS-CoV-2 pandemic. We performed an international prospective cohort study including patients undergoing elective surgery in October 2020. Isolation was defined as the period before surgery during which patients did not leave their house or receive visitors from outside their household. The primary outcome was postoperative pulmonary complications, adjusted in multivariable models for measured confounders. Pre-defined sub-group analyses were performed for the primary outcome. A total of 96,454 patients from 114 countries were included and overall, 26,948 (27.9%) patients isolated before surgery. Postoperative pulmonary complications were recorded in 1947 (2.0%) patients of which 227 (11.7%) were associated with SARS-CoV-2 infection. Patients who isolated pre-operatively were older, had more respiratory comorbidities and were more commonly from areas of high SARS-CoV-2 incidence and high-income countries. Although the overall rates of postoperative pulmonary complications were similar in those that isolated and those that did not (2.1% vs 2.0%, respectively), isolation was associated with higher rates of postoperative pulmonary complications after adjustment (adjusted OR 1.20, 95%CI 1.05–1.36, p = 0.005). Sensitivity analyses revealed no further differences when patients were categorised by: pre-operative testing; use of COVID-19-free pathways; or community SARS-CoV-2 prevalence. The rate of postoperative pulmonary complications increased with periods of isolation longer than 3 days, with an OR (95%CI) at 4–7 days or ≥ 8 days of 1.25 (1.04–1.48), p = 0.015 and 1.31 (1.11–1.55), p = 0.001, respectively. Isolation before elective surgery might be associated with a small but clinically important increased risk of postoperative pulmonary complications. Longer periods of isolation showed no reduction in the risk of postoperative pulmonary complications. These findings have significant implications for global provision of elective surgical care. We aimed to determine the impact of pre-operative isolation on postoperative pulmonary complications after elective surgery during the global SARS-CoV-2 pandemic. We performed an international prospective cohort study including patients undergoing elective surgery in October 2020. Isolation was defined as the period before surgery during which patients did not leave their house or receive visitors from outside their household. The primary outcome was postoperative pulmonary complications, adjusted in multivariable models for measured confounders. Pre-defined sub-group analyses were performed for the primary outcome. A total of 96,454 patients from 114 countries were included and overall, 26,948 (27.9%) patients isolated before surgery. Postoperative pulmonary complications were recorded in 1947 (2.0%) patients of which 227 (11.7%) were associated with SARS-CoV-2 infection. Patients who isolated pre-operatively were older, had more respiratory comorbidities and were more commonly from areas of high SARS-CoV-2 incidence and high-income countries. Although the overall rates of postoperative pulmonary complications were similar in those that isolated and those that did not (2.1% vs 2.0%, respectively), isolation was associated with higher rates of postoperative pulmonary complications after adjustment (adjusted OR 1.20, 95%CI 1.05–1.36, p = 0.005). Sensitivity analyses revealed no further differences when patients were categorised by: pre-operative testing; use of COVID-19-free pathways; or community SARS-CoV-2 prevalence. The rate of postoperative pulmonary complications increased with periods of isolation longer than 3 days, with an OR (95%CI) at 4–7 days or ≥ 8 days of 1.25 (1.04–1.48), p = 0.015 and 1.31 (1.11–1.55), p = 0.001, respectively. Isolation before elective surgery might be associated with a small but clinically important increased risk of postoperative pulmonary complications. Longer periods of isolation showed no reduction in the risk of postoperative pulmonary complications. These findings have significant implications for global provision of elective surgical care