Small signal dynamic model of a self-synchronising current regulated rectifier for a permanent magnet wind energy conversion system (WECS)

Permanent magnet synchronous generators (PMSGs) are attractive for wind energy applications since they can both self-excite and operate at high power densities. Recent work has shown how the rectifiers for these systems can self-synchronise to the stator output voltage using a phase-locked-loop (PLL), and thus control the stator current without requiring rotor position sensors/observers and/or field orientation/direct torque control concepts. This paper now presents a small signal model of this strategy that accounts for the dynamic elements of the current regulator, the PLL, converter modulation delays, and the generator electrical dynamics. The model establishes design principles for this control strategy that confirm its stability when the PLL bandwidth is set to one decade below the current regulator bandwidth. The theoretical findings have been validated using a full-switched model of a PMSG based Wind Energy Conversion System (WECS).Australian Research CouncilMinisterio de Economía, Industria y Competitividad | Ref. DPI2016-75832-

Advances in multidisciplinary tracheostomy care and their impact on the safety and quality of care in the critically ill

Tracheostomy is one of the first recorded surgical procedures and refers to an incision into the windpipe at the front of the neck, classically performed by surgeons to relieve airway obstruction. A tracheostomy tube can be inserted to maintain airway patency. The majority of tracheostomies are now performed the critically ill, typically whilst dependent on invasive respiratory support. Analysis of tracheostomy-related critical incidents helped to understand the frequency, nature and severity of problems that can occur at initial placement or during subsequent use. If problems occur, significant harm may rapidly develop, especially in the critically ill. Recurrent themes that contributed to avoidable mortality include poor emergency management and limitations in infrastructure, equipment provision, staff training and education. Many of the problems identified are amenable to prospective, multidisciplinary quality improvement strategies. This thesis describes my published work in this area. An underlying challenge to improving care lies in the fact that care requires input from many clinical disciplines. Complex patients need care in specialised settings that are not always adequately trained and supported in delivering safe tracheostomy care. My research has evaluated the impact of a co-ordinated multidisciplinary approach using bespoke resources, staff education, infrastructure changes and patient champions to direct healthcare improvements. I have critically appraised my bespoke resources and evaluated and justified the use of a variety of quality and safety metrics to define better care, both at patient-level and using institutional process measures, reflecting better coordination of care, contributing to significant cost savings. Further opportunities to build understanding of the nature of tracheostomy problems in ICU and the success of quality improvement initiatives will be discussed. Future aims are to not only improve care but also to perform a detailed economic analysis and capture knowledge on how to best implement necessary changes rapidly in today’s complex NHS

Small-signal analysis of naturally-sampled single-edge PWM control loops

This paper presents a simple method to analyse the behaviour of feedback loops that contain a naturally-sampled single-edge pulse-width modulator. A small-signal model is derived by means of simple geometric arguments. It is shown how this small-signal model can be used to analyse the stability of the continuous-time pulse-width modulated feedback loop by using standard z-domain techniques. The strategy relies on familiar concepts like transfer functions and small-signal gains and does not require any in-depth knowledge of non-linear systems. A simple design process, where the continuous-time compensator is designed directly in the z-domain, is developed and detailed design equations are derived for a PI current regulator. It is shown how the proposed strategy can accurately predict instability that cannot be explained by means of the well-known average model of the pulse-width modulator. The theoretical analysis is confirmed by means of detailed timedomain simulations. The mechanisms that lead to instability are discussed and an equation for the critical loop gain is derived

Tracheostomy for COVID-19: evolving best practice

From Springer Nature via Jisc Publications RouterHistory: registration 2021-07-06, online 2021-08-31, pub-electronic 2021-08-31, collection 2021-12Publication status: PublishedAbstract: This article is one of ten reviews selected from the Annual Update in Intensive Care and Emergency Medicine 2021. Other selected articles can be found online at https://www.biomedcentral.com/collections/annualupdate2021. Further information about the Annual Update in Intensive Care and Emergency Medicine is available from https://link.springer.com/bookseries/8901

Evolutionary clade affects resistance of Clostridium difficile spores to Cold Atmospheric Plasma

Clostridium difficile is a spore forming bacterium and the leading cause of colitis and antibiotic associated diarrhoea in the developed world. Spores produced by C. difficile are robust and can remain viable for months, leading to prolonged healthcare-associated outbreaks with high mortality. Exposure of C. difficile spores to a novel, non-thermal atmospheric pressure gas plasma was assessed. Factors affecting sporicidal efficacy, including percentage of oxygen in the helium carrier gas admixture, and the effect on spores from different strains representing the five evolutionary C. difficile clades was investigated. Strains from different clades displayed varying resistance to cold plasma. Strain R20291, representing the globally epidemic ribotype 027 type, was the most resistant. However all tested strains displayed a ~3 log reduction in viable spore counts after plasma treatment for 5 minutes. Inactivation of a ribotype 078 strain, the most prevalent clinical type seen in Northern Ireland, was further assessed with respect to surface decontamination, pH, and hydrogen peroxide concentration. Environmental factors affected plasma activity, with dry spores without the presence of organic matter being most susceptible. This study demonstrates that cold atmospheric plasma can effectively inactivate C. difficile spores, and highlights factors that can affect sporicidal activity

Virtual Reality in Simulation-Based Emergency Skills Training: A Systematic Review With a Narrative Synthesis

OBJECTIVE: An important role is predicted for virtual reality (VR) in the future of medical education. We performed a systematic review of the literature with a narrative synthesis, to examine the current evidence for VR in simulation-based emergency skills training. We broadly define emergency skills as any clinical skill used in the emergency care of patients across all clinical settings. METHODS: This systematic review followed the Preferred Reporting Items for Systematic Reviews and Meta Analyses (PRISMA) guidelines. The data sources accessed during this study included: PubMed, CINAHL, EMBASE, AMED, EMCARE, HMIC, BNI, PsychINFO, Medline, CENTRAL, SCOPUS, Web of Science, BIOSIS Citation Index, ERIC, ACM Digital Library, IEEE Xplore, and ProQuest Dissertations and Thesis Global. Cochrane\u27s Rob 2 and ROBVIS tools were used during study quality assessment. No ethical review was required for this work. RESULTS: Thirty-four articles published between 14th March 1998 and 1st March 2022 were included in this review. Studies were predominantly conducted in the USA and Europe and focussed on a variety of healthcare disciplines including medical, nursing, and allied health. VR education was delivered using head-mounted displays, Cave Automatic Virtual Environment systems, and bespoke setups. These systems delivered education in a variety of areas (emergency medicine, equipment training, obstetrics, and basic/advanced life support). Subjective potential advantages of this technology included realism, replayability, and time-effectiveness. Reports of adverse events were low in frequency across the included studies. Whilst clear educational benefit was generally noted, this was not reflected in changes to patient-based outcomes. CONCLUSION: There may be educational benefit to using VR in the context of simulation-based emergency skills training including knowledge gain and retention, skill performance, acceptability, usability, and validity. Currently, there is insufficient evidence to demonstrate clear cost-effectiveness, or direct improvement of patient or institutional outcomes, at this stage

A prospective study of androgen levels, hormone-related genes and risk of rheumatoid arthritis

Introduction Rheumatoid arthritis (RA) is more common in females than males and sex steroid hormones may in part explain this difference. We conducted a case–control study nested within two prospective studies to determine the associations between plasma steroid hormones measured prior to RA onset and polymorphisms in the androgen receptor (AR), estrogen receptor 2 (ESR2), aromatase (CYP19) and progesterone receptor (PGR) genes and RA risk. Methods We genotyped AR, ESR2, CYP19, PGR SNPs and the AR CAG repeat in RA case–control studies nested within the Nurses\u27 Health Study (NHS), NHS II (449 RA cases, 449 controls) and the Women\u27s Health Study (72 cases, and 202 controls). All controls were matched on cohort, age, Caucasian race, menopausal status, and postmenopausal hormone use. We measured plasma dehydroepiandrosterone sulfate (DHEAS), testosterone, and sex hormone binding globulin in 132 pre-RA samples and 396 matched controls in the NHS cohorts. We used conditional logistic regression models adjusted for potential confounders to assess RA risk. Results Mean age of RA diagnosis was 55 years in both cohorts; 58% of cases were rheumatoid factor positive at diagnosis. There was no significant association between plasma DHEAS, total testosterone, or calculated free testosterone and risk of future RA. There was no association between individual variants or haplotypes in any of the genes and RA or seropositive RA, nor any association for the AR CAG repeat. Conclusions Steroid hormone levels measured at a single time point prior to RA onset were not associated with RA risk in this study. Our findings do not suggest that androgens or the AR, ESR2, PGR, and CYP19 genes are important to RA risk in women

Development and evaluation of a risk algorithm predicting alcohol dependence after early onset of regular alcohol use

The ESEMeD project is funded by the European Commission (Contracts QLG5-1999-01042; SANCO 2004123 and EAHC 20081308). The Portuguese Mental Health Study was carried out by the Department of Mental Health, Faculty of Medical Sciences, NOVA University of Lisbon, with collaboration of the Portuguese Catholic University, and was funded by Champalimaud Foundation, Gulbenkian Foundation, Foundation for Science and Technology (FCT) and Ministry of Health.Aims: Likelihood of alcohol dependence (AD) is increased among people who transition to greater levels of alcohol involvement at a younger age. Indicated interventions delivered early may be effective in reducing risk, but could be costly. One way to increase cost-effectiveness would be to develop a prediction model that targeted interventions to the subset of youth with early alcohol use who are at highest risk of subsequent AD. Design: A prediction model was developed for DSM-IV AD onset by age 25 years using an ensemble machine-learning algorithm known as ‘Super Learner’. Shapley additive explanations (SHAP) assessed variable importance. Setting and Participants: Respondents reporting early onset of regular alcohol use (i.e. by 17 years of age) who were aged 25 years or older at interview from 14 representative community surveys conducted in 13 countries as part of WHO's World Mental Health Surveys. Measurements: The primary outcome to be predicted was onset of life-time DSM-IV AD by age 25 as measured using the Composite International Diagnostic Interview, a fully structured diagnostic interview. Findings: AD prevalence by age 25 was 5.1% among the 10 687 individuals who reported drinking alcohol regularly by age 17. The prediction model achieved an external area under the curve [0.78; 95% confidence interval (CI) = 0.74–0.81] higher than any individual candidate risk model (0.73–0.77) and an area under the precision-recall curve of 0.22. Overall calibration was good [integrated calibration index (ICI) = 1.05%]; however, miscalibration was observed at the extreme ends of the distribution of predicted probabilities. Interventions provided to the 20% of people with highest risk would identify 49% of AD cases and require treating four people without AD to reach one with AD. Important predictors of increased risk included younger onset of alcohol use, males, higher cohort alcohol use and more mental disorders. Conclusions: A risk algorithm can be created using data collected at the onset of regular alcohol use to target youth at highest risk of alcohol dependence by early adulthood. Important considerations remain for advancing the development and practical implementation of such models.publishersversionepub_ahead_of_prin