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- Akiyama, Kazunori, et al.
(författare)
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First M87 Event Horizon Telescope Results. II. Array and Instrumentation
- 2019
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Ingår i: Astrophysical Journal Letters. - : American Astronomical Society. - 2041-8213 .- 2041-8205. ; 875:1
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Tidskriftsartikel (refereegranskat)abstract
- The Event Horizon Telescope (EHT) is a very long baseline interferometry (VLBI) array that comprises millimeter- and submillimeter-wavelength telescopes separated by distances comparable to the diameter of the Earth. At a nominal operating wavelength of ∼1.3 mm, EHT angular resolution (λ/D) is ∼25 μas, which is sufficient to resolve nearby supermassive black hole candidates on spatial and temporal scales that correspond to their event horizons. With this capability, the EHT scientific goals are to probe general relativistic effects in the strong-field regime and to study accretion and relativistic jet formation near the black hole boundary. In this Letter we describe the system design of the EHT, detail the technology and instrumentation that enable observations, and provide measures of its performance. Meeting the EHT science objectives has required several key developments that have facilitated the robust extension of the VLBI technique to EHT observing wavelengths and the production of instrumentation that can be deployed on a heterogeneous array of existing telescopes and facilities. To meet sensitivity requirements, high-bandwidth digital systems were developed that process data at rates of 64 gigabit s -1 , exceeding those of currently operating cm-wavelength VLBI arrays by more than an order of magnitude. Associated improvements include the development of phasing systems at array facilities, new receiver installation at several sites, and the deployment of hydrogen maser frequency standards to ensure coherent data capture across the array. These efforts led to the coordination and execution of the first Global EHT observations in 2017 April, and to event-horizon-scale imaging of the supermassive black hole candidate in M87.
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| 3. |
- Akiyama, Kazunori, et al.
(författare)
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First M87 Event Horizon Telescope Results. III. Data Processing and Calibration
- 2019
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Ingår i: Astrophysical Journal Letters. - : American Astronomical Society. - 2041-8213 .- 2041-8205. ; 875:1
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Tidskriftsartikel (refereegranskat)abstract
- We present the calibration and reduction of Event Horizon Telescope (EHT) 1.3 mm radio wavelength observations of the supermassive black hole candidate at the center of the radio galaxy M87 and the quasar 3C 279, taken during the 2017 April 5-11 observing campaign. These global very long baseline interferometric observations include for the first time the highly sensitive Atacama Large Millimeter/submillimeter Array (ALMA); reaching an angular resolution of 25 μas, with characteristic sensitivity limits of ∼1 mJy on baselines to ALMA and ∼10 mJy on other baselines. The observations present challenges for existing data processing tools, arising from the rapid atmospheric phase fluctuations, wide recording bandwidth, and highly heterogeneous array. In response, we developed three independent pipelines for phase calibration and fringe detection, each tailored to the specific needs of the EHT. The final data products include calibrated total intensity amplitude and phase information. They are validated through a series of quality assurance tests that show consistency across pipelines and set limits on baseline systematic errors of 2% in amplitude and 1° in phase. The M87 data reveal the presence of two nulls in correlated flux density at ∼3.4 and ∼8.3 Gλ and temporal evolution in closure quantities, indicating intrinsic variability of compact structure on a timescale of days, or several light-crossing times for a few billion solar-mass black hole. These measurements provide the first opportunity to image horizon-scale structure in M87.
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- Gobom, Johan, et al.
(författare)
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Validation of the LUMIPULSE automated immunoassay for the measurement of core AD biomarkers in cerebrospinal fluid.
- 2022
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Ingår i: Clinical chemistry and laboratory medicine. - : Walter de Gruyter GmbH. - 1437-4331 .- 1434-6621. ; 60:2, s. 207-219
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Tidskriftsartikel (refereegranskat)abstract
- The core cerebrospinal fluid (CSF) biomarkers; total tau (tTau), phospho-tau (pTau), amyloid β1-42(Aβ 1-42), and the Aβ 1-42/Aβ 1-40 ratio have transformed Alzheimer's disease (AD) research and are today increasingly used in clinical routine laboratories as diagnostic tools. Fully automated immunoassay instruments with ready-to-use assay kits and calibrators has simplified their analysis and improved reproducibility of measurements. We evaluated the analytical performance of the fully automated immunoassay instrument LUMIPULSE G (Fujirebio) for measurement of the four core AD CSF biomarkers and determined cutpoints for AD diagnosis.Comparison of the LUMIPULSE G assays was performed with the established INNOTEST ELISAs (Fujirebio) for hTau Ag, pTau 181, β-amyloid 1-42, and with V-PLEX Plus Aβ Peptide Panel 1 (6E10) (Meso Scale Discovery) for Aβ 1-42/Aβ 1-40, as well as with a LC-MS reference method for Aβ 1-42. Intra- and inter-laboratory reproducibility was evaluated for all assays. Clinical cutpoints for Aβ 1-42, tTau, and pTau was determined by analysis of three cohorts of clinically diagnosed patients, comprising 651 CSF samples. For the Aβ 1-42/Aβ 1-40 ratio, the cutpoint was determined by mixture model analysis of 2,782 CSF samples.The LUMIPULSE G assays showed strong correlation to all other immunoassays (r>0.93 for all assays). The repeatability (intra-laboratory) CVs ranged between 2.0 and 5.6%, with the highest variation observed for β-amyloid 1-40. The reproducibility (inter-laboratory) CVs ranged between 2.1 and 6.5%, with the highest variation observed for β-amyloid 1-42. The clinical cutpoints for AD were determined to be 409ng/L for total tau, 50.2ng/L for pTau 181, 526ng/L for β-amyloid 1-42, and 0.072 for the Aβ 1-42/Aβ 1-40 ratio.Our results suggest that the LUMIPULSE G assays for the CSF AD biomarkers are fit for purpose in clinical laboratory practice. Further, they corroborate earlier presented reference limits for the biomarkers.
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- Naoumova, Julia, et al.
(författare)
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Extraction of the deciduous canine as an interceptive treatment in children with palatal displaced canines - part I: shall we extract the deciduous canine or not?
- 2015
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Ingår i: European Journal of Orthodontics. - : Oxford University Press (OUP). - 0141-5387 .- 1460-2210. ; 37:2, s. 209-218
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Tidskriftsartikel (refereegranskat)abstract
- Objectives: To analyse whether extraction of the deciduous canines facilitates eruption of the palatal displaced canines (PDCs), and to analyse root resorption in adjacent teeth caused by the PDCs. Materials and methods: Eligibility criteria for participants were as follows: children at age 10-13 years with either maxillary unilateral or bilateral PDC, persisting deciduous canine and no previous experience of orthodontic treatment. Sixty-seven patients (40 girls and 27 boys; age: mean +/- standard deviation: 11.4 +/- 1.0) with unilateral (45) or bilateral (22) PDCs were consecutively recruited and randomly allocated using permuted block randomization method to extraction or non-extraction. No patients dropped out after the randomization or during the study. Patients underwent a clinical examination and cone beam computed tomography at baseline (T0), after 6 (T1) and 12 months (T2). The total observation time was 24 months. Outcome measures were eruption, positional changes, length of time until eruption, and root resorption of adjacent teeth. The baseline images were measured blinded while the 6- and 12-month control images were not, since it was not possible to blind the extracted canine. Results: Significantly more spontaneous eruptions of the PDCs were seen in the extraction group (EG) than in the control group (CG), with rates of 69 and 39 per cent, respectively, with a mean eruption time of 15.6 +/- 5.6 months in the EG and 18.8 +/- 5.8 months in the CG. Significant differences in changes between the groups, in favour of the EG, were found for all variables except for the sagittal angle. In the EG, the changes in the distances of the canine cusp-tip were larger during the first 6 months, while the change of apex was larger between 6 and 12 months. There were no significant differences in resorption of adjacent teeth between the groups. Limitations: Imputation values were used for the PDCs who had erupted at T2, since no x-rays were taken for ethical reasons, which might have given uncertainty in the positional changes between T1 and T2. Conclusions: Extraction of the deciduous canine is an effective treatment in patients with PDCs. Significantly more positional changes and shorter mean eruption time were seen in the EG. Resorptions of lateral incisors were seen in both groups, but none exceeded grade 2 (resorption up to half of the dentine thickness to the pulp). Registration: This trial was registered in "FoU i Sverige" (http://www.fou.nu/is/sverige), registration number: 40921.
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