18 research outputs found
Design and Development of a Power Modulator for Insulation Testing
No full textI hereby declare that I am the sole author of this thesis. This is a true copy of the thesis, including any required final revisions, as accepted by my examiners. I understand that my thesis may be made electronically available to the public. ii Variable speed drives allow for more precise speed control of induction motors, are of high power factor, and offer fast response characteristics, compared to older technologies, such as motor-generator sets and eddy current clutches. However, due to the high switching frequencies as well as the high dV/dt in the output increased dielectric stresses are produced in the insulation system of the motor they supply. Due to the use of these solid state drives there have been concerns of premature failure in large, medium and high voltage, motors. To fully understand and deal with these concerns requires studying the degradation mechanisms, in the insulation system, caused by these drives; which, on an actual motor is both extremely costly as well as impractical. Therefore, coil samples which accurately represent the construction of the actual insulation system, must be aged and studied instead. In addition, to ideally replicate the aging process, the same waveform that the motor i
Understanding digital bubbles amidst the COVID-19 pandemic: Evidence from DeFi and NFTs()()
No full textThis paper investigates digital financial bubbles amidst the COVID-19 pandemic. Using a sample of 9 DeFi tokens, 3 NFTs, Bitcoin, and Ethereum, we detect several bubbles overlapping the examined cryptoassets. We also uncover DeFi and NFT-specific bubbles in Summer 2020 suggesting distinct driving factors for this class of assets. We document that DeFi and NFTs bubbles are less recurrent but have higher magnitudes than cryptocurrencies’ bubbles. We also find that COVID-19 and trading volume exacerbate bubble occurrences, while Total Value Locked (TVL) is negatively associated with cryptoassets’ bubbles. Our results suggest that TVL can be used as a tool for market monitoring
COVID-19, cryptocurrencies bubbles and digital market efficiency: sensitivity and similarity analysis
No full textThis paper compares the degree of cryptocurrency market efficiency during the pre- and post COVID-19 pandemic with the bubble and non-bubble periods of cryptocurrency markets. Furthermore, it examines and clusters eighteen cryptocurrencies by exploring their market efficiency similarity. Comparing the cryptocurrency bubble periods with the COVID-19 pandemic, the results indicate that this pandemic has the highest impact on cryptocurrency market efficiency. Interestingly, using the dynamic time warping clustering approach, we found evidence on the presence of three clusters that essentially represent mining coins, non-mining coins and token categorizations. 2021The second author would like to thank the financial support of QNRF under the grant number NPRP11C-1229-170007 from the Qatar National Research Fund (a member of Qatar foundation). The statements made herein are solely the responsibility of the author(s).Scopu
Estimation of the Probability of Informed Trading Models Via an Expectation-Conditional Maximization Algorithm
No full textThe estimation of the probability of informed trading (PIN) model and its extensions poses significant challenges owing to various computational problems. To address these issues, we propose a novel estimation method called the expectation-conditional-maximization (ECM) algorithm, which can serve as an alternative to the existing methods for estimating PIN models. Our method provides optimal estimates for the original PIN model as well as two of its extensions: the multilayer PIN model and the adjusted PIN model, along with its restricted versions. Our results indicate that estimations using the ECM algorithm are generally faster, more accurate, and more memory-efficient than the standard methods used in the literature, making it a robust alternative. More importantly, the ECM algorithm is not limited to the models discussed and can be easily adapted to estimate future extensions of the PIN model. © The Author(s) 2025.Hakan Bugra Erentug; Türkiye Bilimsel ve Teknolojik Araştırma Kurumu, TÜBİTAK, (122K637)Social Science Citation Inde
Powered vs manual tooth brushing in patients with fixed orthodontic appliances:A systematic review and meta-analysis
No full textObjective: The objective of this systematic review and meta-analysis was to compare powered and manual toothbrushes for oral hygiene maintenance in orthodontic patients.Methods: Electronic databases, including MEDLINE, Scopus, Google scholar, PubMed, Web of Science, the Cochrane Oral Health Group's Trials Register, and CENTRAL, were searched without language restrictions. Randomized clinical trials directly comparing manual and powered toothbrushing including patients with fixed orthodontic appliances reporting predefined outcomes with a follow-up period of at least 4 weeks were included. Using predefined data extraction forms, 2 authors independently undertook data extraction with conflict resolution by the third author. Quality assessment was based on the Cochrane Risk of Bias tool, and overall evidence base was assessed using the Grading of Recommendations Assessment, Development and Evaluation system. A random effects meta-analysis combined the treatment effects across studies.Results: Five trials were considered appropriate for inclusion in the meta-analysis with 8 trials excluded. There are slight differences in plaque index reduction of 0.05 (−0.04, 0.13) and 0.11 (−0.10, 0.33) at 4 week and 8 week follow up, respectively, favoring manual toothbrushing, but this was not statistically significant. There are slight differences in gingival index reduction of −0.02 (−0.06, 0.02) and −0.01 (−0.05, 0.02) at 4 week and 8 week follow up, respectively, favoring powered brushing, but again, this was not statistically significant. The overall quality of evidence was very low to moderate for the primary outcomes.Conclusions: Using manual or powered tooth brushing with fixed orthodontic appliances does not reduce plaque or gingival indexes at 4 weeks and 8 weeks. This conclusion is, however, based on low quality of evidence from few studies. Greater standardization of the methodology used is desirable in future trials to increase our confidence in these findings.</p
Identification of heart rate-associated loci and their effects on cardiac conduction and rhythm disorders
No full textElevated resting heart rate is associated with greater risk of cardiovascular disease and mortality. In a 2-stage meta-analysis of genome-wide association studies in up to 181,171 individuals, we identified 14 new loci associated with heart rate and confirmed associations with all 7 previously established loci. Experimental downregulation of gene expression in Drosophila melanogaster and Danio rerio identified 20 genes at 11 loci that are relevant for heart rate regulation and highlight a role for genes involved in signal transmission, embryonic cardiac development and the pathophysiology of dilated cardiomyopathy, congenital heart failure and/or sudden cardiac death. In addition, genetic susceptibility to increased heart rate is associated with altered cardiac conduction and reduced risk of sick sinus syndrome, and both heart rate-increasing and heart rate-decreasing variants associate with risk of atrial fibrillation. Our findings provide fresh insights into the mechanisms regulating heart rate and identify new therapeutic targets
[[alternative]]Author Correction: Inherited causes of clonal haematopoiesis in 97,691 whole genomes (Nature, (2020), 586, 7831, (763-768), 10.1038/s41586-020-2819-2)
No full text[[abstract]]In this Article, Abhishek Niroula should have been listed as an author, with the affiliations: Broad Institute of MIT and Harvard, Cambridge, MA, USA; and Department of Medical Oncology, Dana-Farber Cancer Institute, Boston, MA, USA. They performed additional bioinformatic analyses (see ‘Author contributions’). The original Article has been corrected online. *A list of authors and their affiliations appears online
Serial lung ultrasound in predicting the need for surfactant and respiratory course in preterm infants—multicentre observational study (SLURP)
No full text\ua9 The Author(s) 2025.Lung ultrasound (LUS) scores may predict surfactant need early and the progression of the respiratory course in preterm infants. The objective of this study is to report the diagnostic value of LUS scores performed by operators of varying levels of experience to predict the need for surfactant in preterm infants. A prospective observational study was conducted across 3 UK-based neonatal intensive care units. Preterm infants ≤ 34 weeks on non-invasive respiratory support within 3 h of birth were included. Ten lung zones were scored serially, first within the first 3 h of life, then at 12–24-h intervals (a total of four scans). All scans were performed by the local team members with formal training on LUS and varying levels of expertise. All the LUS videos were scored by an expert investigator who was blinded to clinical details. Written retrospective parental consents were obtained. We recruited 83 preterm infants ≤ 34 weeks (May 2023 to June 2024). A total of 325 LUS scans were performed by 27 clinical staff. The median birth gestational age and birth weight were 31 weeks and 1515 g, respectively. Twenty-eight (34%) babies received surfactants. The first LUS using a 6-zone method within 3 h of life predicted surfactant need and bronchopulmonary dysplasia with an AUC of 0.80 for both outcomes, offering sensitivity (79% and 73%) and specificity (75% and 76%), respectively. Conclusions: LUS performed by operators of varying levels of experience within the first 3 h of life is a reliable tool for predicting surfactant need in preterm infants ≤ 34 weeks. Trial registration: ClinicalTrials.gov (https://clinicaltrials.gov/): NCT05782569. (Table presented.
Correction: The Influence of Age and Sex on Genetic Associations with Adult Body Size and Shape: A Large-Scale Genome-Wide Interaction Study
No full textThe arcOGEN Consortium should be listed as an author of this article. They contributed to the genome-wide association study results presented in this work. They should be listed in the author byline at position 292 and affiliated with The Arthritis Research UK Osteoarthritis Genetics Consortium. They should also be included in the footnote designating consortia which is underneath the author affiliation list in the PDF version of the article, and in the S2 Text. Please view the correct S2 Text below, containing correct consortia members
