| 1. |
- Botvinik-Nezer, Rotem, et al.
(författare)
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Variability in the analysis of a single neuroimaging dataset by many teams
- 2020
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Ingår i: Nature. - : Springer Science and Business Media LLC. - 0028-0836 .- 1476-4687. ; 582, s. 84-88
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Tidskriftsartikel (refereegranskat)abstract
- Data analysis workflows in many scientific domains have become increasingly complex and flexible. Here we assess the effect of this flexibility on the results of functional magnetic resonance imaging by asking 70 independent teams to analyse the same dataset, testing the same 9 ex-ante hypotheses(1). The flexibility of analytical approaches is exemplified by the fact that no two teams chose identical workflows to analyse the data. This flexibility resulted in sizeable variation in the results of hypothesis tests, even for teams whose statistical maps were highly correlated at intermediate stages of the analysis pipeline. Variation in reported results was related to several aspects of analysis methodology. Notably, a meta-analytical approach that aggregated information across teams yielded a significant consensus in activated regions. Furthermore, prediction markets of researchers in the field revealed an overestimation of the likelihood of significant findings, even by researchers with direct knowledge of the dataset(2-5). Our findings show that analytical flexibility can have substantial effects on scientific conclusions, and identify factors that may be related to variability in the analysis of functional magnetic resonance imaging. The results emphasize the importance of validating and sharing complex analysis workflows, and demonstrate the need for performing and reporting multiple analyses of the same data. Potential approaches that could be used to mitigate issues related to analytical variability are discussed. The results obtained by seventy different teams analysing the same functional magnetic resonance imaging dataset show substantial variation, highlighting the influence of analytical choices and the importance of sharing workflows publicly and performing multiple analyses.
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| 2. |
- Devaux, Yvan, et al.
(författare)
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Association of circulating MicroRNA-124-3p levels with outcomes after out-of-hospital cardiac arrest : A substudy of a randomized clinical trial
- 2016
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Ingår i: JAMA Cardiology. - : American Medical Association (AMA). - 2380-6583. ; 1:3, s. 305-313
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Tidskriftsartikel (refereegranskat)abstract
- IMPORTANCE: The value of microRNAs (miRNAs) as biomarkers has been investigated in various clinical contexts. Initial small-scale studies suggested that miRNAs might be useful indicators of outcome after cardiac arrest. OBJECTIVE: To address the prognostic value of circulating miRNAs in a large cohort of comatose patients with out-of-hospital cardiac arrest. DESIGN, SETTING, AND PARTICIPANTS: This substudy of the Target Temperature Management After Cardiac Arrest (TTM) trial, a multicenter randomized, parallel-group, assessor-blinded clinical trial, compared the 6-month neurologic outcomes and survival of patients with cardiac arrest after targeted temperature management at 33°C or 36°C. Five hundred seventy-nine patients who survived the first 24 hours after the return of spontaneous circulation and who had blood samples available for miRNA assessment were enrolled from 29 intensive care units in 9 countries from November 11, 2010, to January 10, 2013. Final follow-up was completed on July 3, 2013, and data were assessed from February 1, 2014, to February 1, 2016. INTERVENTIONS: Blood sampling at 48 hours after the return of spontaneous circulation. MAINOUTCOMES AND MEASURES: The primary end point was poor neurologic outcomeat6 months (cerebral performance category score, 3 [severe neurologic sequelae], 4 [coma], or 5 [death]). The secondary end point was survival until the end of the trial. Circulating levels of miRNAs were measured by sequencing and polymerase chain reaction. RESULTS: Of the 579 patients (265 men [80.3%]; mean [SD] age, 63 [12] years), 304 patients (52.5%) hada poor neurologic outcomeat 6months. Inthe discovery phase with short RNA sequencing in 50 patients, the brain-enriched miR-124-3p level was identified as a candidate prognostic variable for neurologic outcomes. In the validation cohort of 529 patients, mean (SD) levels of miR-124-3p were higher in patients with a poor outcome (8408 [12 465] copies/μL) compared with patients with a good outcome (1842 [3025] copies/μL; P < .001). The miR-124-3p level was significantly associated with neurologic outcomes in the univariable analysis (odds ratio, 6.72; 95% CI, 4.53-9.97). In multivariable analyses using logistic regression, miR-124-3p levels were independently associated with neurologic outcomes (odds ratio, 1.62; 95% CI, 1.13-2.32). In Cox proportional hazards models, higher levels of miR-124-3p were significantly associated with lower survival (hazard ratio, 1.63; 95% CI, 1.37-1.93). CONCLUSIONS AND RELEVANCE: Levels of miR-124-3p can be used as prognostication tools for neurologic outcome and survival after out-of-hospital cardiac arrest. Thus, miRNA levels may aid in tailoring health care for patients with cardiac arrest.
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| 3. |
- Gunnarsson, Svante, et al.
(författare)
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Iterative Feedback Tuning Applied to Robot Joint Controllers
- 1999
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Ingår i: Proceedings of the 14th IFAC World Congress. - 9780080432137 ; , s. 451-456
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Konferensbidrag (refereegranskat)abstract
- Tuning of robot joint controllers using iterative feedback tuning (IFT) is considered. Using a simulation model of a two-link robot arm the applicability of IFT is investigated for a nonlinear and multivariable system. Due to the strong crosscoupling between the two links a decoupling controller is needed in order to obtain satisfactory results. An approach for obtaining a decoupling controller is investigated. It is also shown how IFT can be used to tune the controller parameters for a particular trajectory of the arm.
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| 4. |
- Gunnarsson, Svante, et al.
(författare)
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Iterative Feedback Tuning Applied to Robot Joint Controllers
- 1998
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Rapport (övrigt vetenskapligt/konstnärligt)abstract
- Tuning of robot joint controllers using iterative feedback tuning (IFT) is considered. Using a simulation model of a two-link robot arm the applicability of IFT is investigated for a nonlinear and multivariable system. Due to the strong crosscoupling between the two links a decoupling controller is needed in order to obtain satisfactory results. An approach for obtaining a decoupling controller is investigated. It is also shown how IFT can be used to tune the controller parameters for a particular trajectory of the arm.
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| 5. |
- Gunnarsson, Svante, et al.
(författare)
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Tuning of a Decoupling Controller for a 2×2 System using Iterative Feedback Tuning
- 2003
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Ingår i: Control Engineering Practice. - : Elsevier. - 0967-0661 .- 1873-6939. ; 11:9, s. 1035-1041
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Tidskriftsartikel (refereegranskat)abstract
- Iterative feedback tuning is used to tune a decoupling controller for a 2 × 2 multivariable system. The tuning is carried out in two steps. In the first step the coefficients of two proportional decoupling controllers are tuned, and in the second step two PD-controllers are tuned. The approach is evaluated on a nonlinear simulation model of a two-link manipulator. The evaluation is carried out using two different reference trajectories and also in the presence of friction. The resulting closed loop systems show satisfactory behavior in all three cases.
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| 6. |
- Munk, P., et al.
(författare)
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Genomic analysis of sewage from 101 countries reveals global landscape of antimicrobial resistance
- 2022
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Ingår i: Nature Communications. - : Springer Science and Business Media LLC. - 2041-1723. ; 13:1
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Tidskriftsartikel (refereegranskat)abstract
- Antimicrobial resistance (AMR) is a major threat to global health. Understanding the emergence, evolution, and transmission of individual antibiotic resistance genes (ARGs) is essential to develop sustainable strategies combatting this threat. Here, we use metagenomic sequencing to analyse ARGs in 757 sewage samples from 243 cities in 101 countries, collected from 2016 to 2019. We find regional patterns in resistomes, and these differ between subsets corresponding to drug classes and are partly driven by taxonomic variation. The genetic environments of 49 common ARGs are highly diverse, with most common ARGs carried by multiple distinct genomic contexts globally and sometimes on plasmids. Analysis of flanking sequence revealed ARG-specific patterns of dispersal limitation and global transmission. Our data furthermore suggest certain geographies are more prone to transmission events and should receive additional attention.
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| 7. |
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| 8. |
- Stammet, Pascal, et al.
(författare)
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Protein S100 as outcome predictor after out-of-hospital cardiac arrest and targeted temperature management at 33 °C and 36 °C
- 2017
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Ingår i: Critical Care. - : Springer Science and Business Media LLC. - 1364-8535. ; 21:1
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Tidskriftsartikel (refereegranskat)abstract
- Background: We aimed to investigate the diagnostic performance of S100 as an outcome predictor after out-of-hospital cardiac arrest (OHCA) and the potential influence of two target temperatures (33 °C and 36 °C) on serum levels of S100. Methods: This is a substudy of the Target Temperature Management after Out-of-Hospital Cardiac Arrest (TTM) trial. Serum levels of S100 were measured a posteriori in a core laboratory in samples collected at 24, 48, and 72 h after OHCA. Outcome at 6 months was assessed using the Cerebral Performance Categories Scale (CPC 1-2 = good outcome, CPC 3-5 = poor outcome). Results: We included 687 patients from 29 sites in Europe. Median S100 values were higher in patients with a poor outcome at 24, 48, and 72 h: 0.19 (IQR 0.10-0.49) versus 0.08 (IQR 0.06-0.11) μg/ml, 0.16 (IQR 0.10-0.44) versus 0.07 (IQR 0.06-0.11) μg/L, and 0.13 (IQR 0.08-0.26) versus 0.06 (IQR 0.05-0.09) μg/L (p < 0.001), respectively. The ability to predict outcome was best at 24 h with an AUC of 0.80 (95% CI 0.77-0.83). S100 values were higher at 24 and 72 h in the 33 °C group than in the 36 °C group (0.12 [0.07-0.22] versus 0.10 [0.07-0.21] μg/L and 0.09 [0.06-0.17] versus 0.08 [0.05-0.10], respectively) (p < 0.02). In multivariable analyses including baseline variables and the allocated target temperature, the addition of S100 improved the AUC from 0.80 to 0.84 (95% CI 0.81-0.87) (p < 0.001), but S100 was not an independent outcome predictor. Adding S100 to the same model including neuron-specific enolase (NSE) did not further improve the AUC. Conclusions: The allocated target temperature did not affect S100 to a clinically relevant degree. High S100 values are predictive of poor outcome but do not add value to present prognostication models with or without NSE. S100 measured at 24 h and afterward is of limited value in clinical outcome prediction after OHCA. Trial registration: ClinicalTrials.gov identifier: NCT01020916. Registered on 25 November 2009.
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