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- Bugge, M. D., et al.
(författare)
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Reactive hyperemia and baseline pulse amplitude among smelter workers exposed to fine and ultrafine particles
- 2020
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Ingår i: International Archives of Occupational and Environmental Health. - : Springer Science and Business Media LLC. - 0340-0131 .- 1432-1246. ; 93, s. 399-407
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Tidskriftsartikel (refereegranskat)abstract
- Objective: Ambient exposure to fine particles is associated with increased cardiovascular morbidity and mortality. Associations between occupational particulate matter (PM) exposure and cardiovascular disease have been studied less. The objective of this study was to examine associations between PM exposure and endothelial function among workers in Norwegian smelters. Methods: We examined endothelial function with Endo-PAT equipment after a working day (WD) and on a day off (DO) in 59 furnace workers recruited from three metal smelters in Norway. The difference in baseline pulse amplitude (BPA) and reactive hyperemia index (RHI) between the 2days was analysed in relation to individual exposure to PM < 250nm (PM250) or the respirable aerosol fraction of particles, and adjusted for relevant covariates. Results: The exposure to PM250 ranged from 0.004 to 5.7mg/m3. The mean BPA was significantly higher on WD relative to DO (772 vs. 535, p = 0.001). This difference was associated with PM concentrations among participants ≥ 34years, but not among the younger workers. Reactive hyperemia was significantly lower on workdays relative to days off (1.70 vs. 1.84, p = 0.05). This difference was observed only among participants above the age 34. No associations with PM exposure were observed. Conclusions: PM exposure was associated with higher BPA among participants older than 34years. BPA reflects microvessel pulsatility. Our results may indicate an age-dependent cardiovascular susceptibility to PM exposure. Endothelial function measured by RHI was reduced on WD among participants 34years and older, but we found no associations between PM exposure and RHI. © 2019, The Author(s).
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- Dyrhovden, Ruben, et al.
(författare)
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Managing Contamination and Diverse Bacterial Loads in 16S rRNA Deep Sequencing of Clinical Samples : Implications of the Law of Small Numbers
- 2021
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Ingår i: mBio. - : American Society for Microbiology. - 2161-2129 .- 2150-7511. ; 12:3
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Tidskriftsartikel (refereegranskat)abstract
- In this article, we investigate patterns of microbial DNA contamination in targeted 16S rRNA amplicon sequencing (16S deep sequencing) and demonstrate how this can be used to filter background bacterial DNA in diagnostic microbiology. We also investigate the importance of sequencing depth. We first determined the patterns of contamination by performing repeat 16S deep sequencing of negative and positive extraction controls. This process identified a few bacterial species dominating across all replicates but also a high intersample variability among low abundance contaminant species in replicates split before PCR amplification. Replicates split after PCR amplification yielded almost identical sequencing results. On the basis of these observations, we suggest using the abundance of the most dominant contaminant species to define a threshold in each clinical sample from where identifications with lower abundances possibly represent contamination. We evaluated this approach by sequencing of a diluted, staggered mock community and of bile samples from 41 patients with acute cholangitis and noninfectious bile duct stenosis. All clinical samples were sequenced twice using different sequencing depths. We were able to demonstrate the following: (i) The high intersample variability between sequencing replicates is caused by events occurring before or during the PCR amplification step. (ii) Knowledge about the most dominant contaminant species can be used to establish sample-specific cutoffs for reliable identifications. (iii) Below the level of the most abundant contaminant, it rapidly becomes very demanding to reliably discriminate between background and true findings. (iv) Adequate sequencing depth can be claimed only when the analysis also picks up background contamination. IMPORTANCE There has been a gradual increase in 16S deep sequencing studies on infectious disease materials. Management of bacterial DNA contamination is a major challenge in such diagnostics, particularly in low biomass samples. Reporting a contaminant species as a relevant pathogen may cause unnecessary antibiotic treatment or even falsely classify a noninfectious condition as a bacterial infection. Yet, there are few studies on how to filter contamination in clinical microbiology. Here, we demonstrate that sequencing of extraction controls will not reveal the full spectrum of contaminants that could occur in the associated clinical samples. Only the most abundant contaminant species were consistently detected, and we present how this can be used to set sample specific thresholds for reliable identifications. We believe this work can facilitate the implementation of 16S deep sequencing in diagnostic laboratories. The new data we provide on the patterns of microbial DNA contamination is also important for microbiome research.
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- Stellas, D., et al.
(författare)
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Position-sensorless control of a submersible PMSM fed over a long cable and two transformers
- 2014
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Ingår i: 2014 16th European Conference on Power Electronics and Applications (EPE'14-ECCE Europe), Lappeenranta, Finland, 26-28 August 2014. - 2325-0313. - 9781479930159
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Konferensbidrag (refereegranskat)abstract
- This paper proposes the combination of two sensorless control algorithms for the secure start-up and the efficient operation of a remotely-controlled PMSM. V / f control is applied during the start-up of the motor and vector control is used for operation at higher speeds. The investigated system consists of a long step-out configuration with a cable and two transformers between the PMSM and its VSD. The system is tested with simulations and with experiments on a lab model. The results demonstrate that V / f control can safely start the PMSM. The effect of the inertia of the rotating assembly, the load torque and the initial rotor position on the start-up performance of the system is investigated and the successful transition from V / f control to vector control is demonstrated.
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