6,268 research outputs found

    Losses in grid and inverter supplied induction machine drives

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    Estimating rotational iron losses in an induction machine

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    A framework for space–time modelling of rainfall events for hydrological applications of weather radar

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    \ua9 2024 The Author(s). High-resolution rainfall fields are a crucial tool for many hydrological and hydrodynamic applications, including flood forecasting and urban drainage design. The aim of this study is to explore and exploit the space–time properties of rainfall using Fast-Fourier transforms, to provide a new method for the generation of high-resolution synthetic rainfall grids. These fields have realistic spatio-temporal properties, parametrised using historical radar rainfall events, matching the resolution of weather radar data (1km, 5 min), for events with a duration of 0.5–6 h. Utilising spectral random field theory, simulated rainfall fields are generated with a prescribed correlation structure, anisotropy, advection and marginal rainfall rate proportions and distributions. A model for rainfall generation is demonstrated, with an enriched model parameter sampling architecture using meaningful event clustering, based on space–time event properties. This model framework performs well at recreating short-duration spatio-temporal rainfall events, both visually and statistically. The extension of a clustered rainfall model allows for larger-scale sampling of synthetic event parameters, with specific rainfall event types. There are numerous potential uses for this rainfall model, such as design storms or test cases for applications of radar rainfall estimates. These include but are not limited to nowcasting, numerical weather prediction, flash flood forecasting and machine learning model training data generation

    Prevalence of Blomia tropicalis allergy in two regions of South Africa

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    Background. Asthma and allergic rhinitis affect 15% and 38% of South African (SA) children, respectively. The housedust mite (HDM) is the most significant indoor aeroallergen. Typical HDM species include Dermatophagoides pteronyssinus, D. farinae and Blomia tropicalis. Conventional skin-prick testing (SPT) panels only test for Dermatophagoides. B. tropicalis has been described in the tropical and subtropical regions, but is not routinely tested for in SA.Objective. To ascertain the significance of B. tropicalis as an aeroallergen in northern coastal KwaZulu-Natal Province (KZN), a tropical environment, and in Johannesburg in the highveld, where the climate is milder and less humid.Methods. Children aged 1 - 18 years with features of allergic rhinitis and/or asthma were recruited over a 6-month period from Alberlito Hospital in northern KZN and the Clinton Clinic in Johannesburg. SPTs included Dermatophagoides and B. tropicalis. Sensitisation was defined as a wheal 3 mm greater than the negative control.Results. Eighty-five subjects were included, 50 in northern KZN and 35 in the Johannesburg arm; 52% of subjects in northern KZN and 3% in Johannesburg were sensitised to B. tropicalis, with a significant difference between these centres (p<0.05). Of the 52% sensitised to B. tropicalis in northern KZN, half were sensitised only to B. tropicalis.Conclusion. There is a high prevalence of B. tropicalis allergy in the tropical northern KZN region and a much lower prevalence in the Johannesburg region. Routine testing for B. tropicalis allergy should be employed in northern KZN

    The microbiome in chronic inflammatory airway disease: A threatened species

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    The human body is exposed to a multitude of microbes and infectious organisms  throughout life. Many of these organisms colonise the skin, gastrointestinal tract (GIT) and airway. We now recognise that this colonisation includes the lower airway,   previously thought to be sterile. These colonising organisms play an important role in disease prevention, including an array of chronic inflammatory conditions that are unrelated to infectious diseases. However, new evidence of immune dysregulation suggests that early colonisation, especially of the GIT and airway, by pathogenic micro-organisms, has deleterious effects that may contribute to the potential to induce  chronic inflammation in young children, which may only express itself in adult life

    Weathering the crisis: Evidence of diffuse support for the EU from a six-wave Dutch panel

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    Political regimes draw legitimacy from diffuse political support. How diffuse is support for the European Union? By focusing on cross-sectional data, the extant literature fails to demonstrate that support for the European Union displays the key defining characteristic of diffuse support: individual-level stability over a time of crisis. I use a six-wave panel data set from the Netherlands to study stability in support for the European Parliament during the 2008 economic crisis. I argue that public support for the European Parliament is highly diffuse. Using three analytical techniques, I find that individual-level support for the European Parliament remained highly stable from 2007 to 2012. These results suggest that in times of crisis, the European Union can draw on mass public support as a source of resilience

    Deep Brain Stimulation for Parkinson's Disease with Early Motor Complications: A UK Cost-Effectiveness Analysis

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    This is the final version of the article. Available from Public Library of Science via the DOI in this record.BACKGROUND: Parkinson's disease (PD) is a debilitating illness associated with considerable impairment of quality of life and substantial costs to health care systems. Deep brain stimulation (DBS) is an established surgical treatment option for some patients with advanced PD. The EARLYSTIM trial has recently demonstrated its clinical benefit also in patients with early motor complications. We sought to evaluate the cost-effectiveness of DBS, compared to best medical therapy (BMT), among PD patients with early onset of motor complications, from a United Kingdom (UK) payer perspective. METHODS: We developed a Markov model to represent the progression of PD as rated using the Unified Parkinson's Disease Rating Scale (UPDRS) over time in patients with early PD. Evidence sources were a systematic review of clinical evidence; data from the EARLYSTIM study; and a UK Clinical Practice Research Datalink (CPRD) dataset including DBS patients. A mapping algorithm was developed to generate utility values based on UPDRS data for each intervention. The cost-effectiveness was expressed as the incremental cost per quality-adjusted life-year (QALY). One-way and probabilistic sensitivity analyses were undertaken to explore the effect of parameter uncertainty. RESULTS: Over a 15-year time horizon, DBS was predicted to lead to additional mean cost per patient of £26,799 compared with BMT (£73,077/patient versus £46,278/patient) and an additional mean 1.35 QALYs (6.69 QALYs versus 5.35 QALYs), resulting in an incremental cost-effectiveness ratio of £19,887 per QALY gained with a 99% probability of DBS being cost-effective at a threshold of £30,000/QALY. One-way sensitivity analyses suggested that the results were not significantly impacted by plausible changes in the input parameter values. CONCLUSION: These results indicate that DBS is a cost-effective intervention in PD patients with early motor complications when compared with existing interventions, offering additional health benefits at acceptable incremental cost. This supports the extended use of DBS among patients with early onset of motor complications.Funding: Medtronic funded the development of the model, including consulting fees to physicians and health economic specialists, sponsored a medical writer and reviewed the manuscript. The funders provided input on the study design, decision to publish, and preparation of the manuscript. HTA Consulting provided support in the form of salaries for authors [TF], and staff resources to support evidence review and synthesis. They did not have any additional role in the study design and analysis, decision to publish, or preparation of the manuscript. The specific roles of these authors are articulated in the ‘author contributions’ section

    Cricket pace bowling: The trade-off between optimising knee angle for performance advantages v. injury prevention

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    Background. The cricket pace bowler utilises various strategies, including a more extended front knee angle, to achieve optimal performance benefits. At times this is done to the detriment of injury  prevention.Objective. To investigate the relationship between three-dimensional (3D) knee kinematics during pace bowling action, injury incidence and bowling performance at the start and end of a cricket season.Methods. Knee angle and ball release (BR) speed of injury-free premier league (club level) cricket pace bowlers over the age of 18 years were measured at the start and end of the cricket season. Kinematic, injury- and bowling performance-related (BR speed and accuracy) data were analysed using paired and independent Student's t-tests, Pearson's correlation coefficient,χ2 test and a two-way analysis of covariance with repeated measures.Results. Thirty-one bowlers participated in this study, and kinematic data of a subset of 17 were  analysed. Nine bowlers (53%) sustained injuries during the cricket season. No statistically significant relationship was found between knee angle and injury. Bowlers who did not sustain an injury bowled with more knee flexion at the start of the season (mean (standard deviation) 157.07° (12.02°)) than at the end of it (163.95° (6.97°)) (p=0.01). There was no interaction between accuracy and knee angle. There  was a good to excellent inverse correlation between BR speed and knee angle among bowlers who  remained injury free (r=.0.79; p=0.18).Conclusion. Bowlers who remain injury free during the course of the season may use strategies other than the front knee angle to facilitate high BR speeds. Technique-related variables which are more  'protective' against injuries while allowing for higher BR speeds should be further investigated among bowlers
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