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Sökning: WFRF:(Bremer Alexander)

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1.
  • Akiyama, Kazunori, et al. (författare)
  • The persistent shadow of the supermassive black hole of M 87: I. Observations, calibration, imaging, and analysis*
  • 2024
  • Ingår i: Astronomy and Astrophysics. - 0004-6361 .- 1432-0746. ; 681
  • Tidskriftsartikel (refereegranskat)abstract
    • In April 2019, the Event Horizon Telescope (EHT) Collaboration reported the first-ever event-horizon-scale images of a black hole, resolving the central compact radio source in the giant elliptical galaxy M 87. These images reveal a ring with a southerly brightness distribution and a diameter of ∼42 μas, consistent with the predicted size and shape of a shadow produced by the gravitationally lensed emission around a supermassive black hole. These results were obtained as part of the April 2017 EHT observation campaign, using a global very long baseline interferometric radio array operating at a wavelength of 1.3 mm. Here, we present results based on the second EHT observing campaign, taking place in April 2018 with an improved array, wider frequency coverage, and increased bandwidth. In particular, the additional baselines provided by the Greenland telescope improved the coverage of the array. Multiyear EHT observations provide independent snapshots of the horizon-scale emission, allowing us to confirm the persistence, size, and shape of the black hole shadow, and constrain the intrinsic structural variability of the accretion flow. We have confirmed the presence of an asymmetric ring structure, brighter in the southwest, with a median diameter of 43.3-3.1+1.5 μas. The diameter of the 2018 ring is remarkably consistent with the diameter obtained from the previous 2017 observations. On the other hand, the position angle of the brightness asymmetry in 2018 is shifted by about 30 relative to 2017. The perennial persistence of the ring and its diameter robustly support the interpretation that the ring is formed by lensed emission surrounding a Kerr black hole with a mass ∼6.5× 109M. The significant change in the ring brightness asymmetry implies a spin axis that is more consistent with the position angle of the large-scale jet.
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2.
  • Demichev, Vadim, et al. (författare)
  • A time-resolved proteomic and prognostic map of COVID-19
  • 2021
  • Ingår i: Cell Systems. - : Elsevier BV. - 2405-4712 .- 2405-4720. ; 12:8, s. 780-794.e7
  • Tidskriftsartikel (refereegranskat)abstract
    • COVID-19 is highly variable in its clinical presentation, ranging from asymptomatic infection to severe organ damage and death. We characterized the time-dependent progression of the disease in 139 COVID-19 inpatients by measuring 86 accredited diagnostic parameters, such as blood cell counts and enzyme activities, as well as untargeted plasma proteomes at 687 sampling points. We report an initial spike in a systemic inflammatory response, which is gradually alleviated and followed by a protein signature indicative of tissue repair, metabolic reconstitution, and immunomodulation. We identify prognostic marker signatures for devising risk-adapted treatment strategies and use machine learning to classify therapeutic needs. We show that the machine learning models based on the proteome are transferable to an independent cohort. Our study presents a map linking routinely used clinical diagnostic parameters to plasma proteomes and their dynamics in an infectious disease.
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4.
  • Kim, Jae-Young, et al. (författare)
  • Event Horizon Telescope imaging of the archetypal blazar 3C 279 at an extreme 20 microarcsecond resolution
  • 2020
  • Ingår i: Astronomy and Astrophysics. - : EDP Sciences. - 0004-6361 .- 1432-0746. ; 640
  • Tidskriftsartikel (refereegranskat)abstract
    • 3C 279 is an archetypal blazar with a prominent radio jet that show broadband flux density variability across the entire electromagnetic spectrum. We use an ultra-high angular resolution technique - global Very Long Baseline Interferometry (VLBI) at 1.3mm (230 GHz) - to resolve the innermost jet of 3C 279 in order to study its fine-scale morphology close to the jet base where highly variable-ray emission is thought to originate, according to various models. The source was observed during four days in April 2017 with the Event Horizon Telescope at 230 GHz, including the phased Atacama Large Millimeter/submillimeter Array, at an angular resolution of ∼20 μas (at a redshift of z = 0:536 this corresponds to ∼0:13 pc ∼ 1700 Schwarzschild radii with a black hole mass MBH = 8 × 108 M⊙). Imaging and model-fitting techniques were applied to the data to parameterize the fine-scale source structure and its variation.We find a multicomponent inner jet morphology with the northernmost component elongated perpendicular to the direction of the jet, as imaged at longer wavelengths. The elongated nuclear structure is consistent on all four observing days and across diffierent imaging methods and model-fitting techniques, and therefore appears robust. Owing to its compactness and brightness, we associate the northern nuclear structure as the VLBI "core". This morphology can be interpreted as either a broad resolved jet base or a spatially bent jet.We also find significant day-to-day variations in the closure phases, which appear most pronounced on the triangles with the longest baselines. Our analysis shows that this variation is related to a systematic change of the source structure. Two inner jet components move non-radially at apparent speeds of ∼15 c and ∼20 c (∼1:3 and ∼1:7 μas day-1, respectively), which more strongly supports the scenario of traveling shocks or instabilities in a bent, possibly rotating jet. The observed apparent speeds are also coincident with the 3C 279 large-scale jet kinematics observed at longer (cm) wavelengths, suggesting no significant jet acceleration between the 1.3mm core and the outer jet. The intrinsic brightness temperature of the jet components are ≤1010 K, a magnitude or more lower than typical values seen at ≥7mm wavelengths. The low brightness temperature and morphological complexity suggest that the core region of 3C 279 becomes optically thin at short (mm) wavelengths.
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5.
  • Löhle, Matthias, et al. (författare)
  • Application of single wrist-wearable accelerometry for objective motor diary assessment in fluctuating Parkinson's disease
  • 2023
  • Ingår i: npj Digital Medicine. - 2398-6352. ; 6:1
  • Tidskriftsartikel (refereegranskat)abstract
    • Advanced Parkinson's disease (PD) is characterized by motor fluctuations including unpredictable oscillations remarkably impairing quality of life. Effective management and development of novel therapies for these response fluctuations largely depend on clinical rating instruments such as the widely-used PD home diary, which are associated with biases and errors. Recent advancements in digital health technologies provide user-friendly wearables that can be tailored for continuous monitoring of motor fluctuations. Their criterion validity under real-world conditions using clinical examination as the gold standard remains to be determined. We prospectively examined this validity of a wearable accelerometer-based digital Parkinson's Motor Diary (adPMD) using the Parkinson's Kinetigraph (PKG ®) in an alternative application by converting its continuous data into one of the three motor categories of the PD home diary (Off, On and Dyskinetic state). Sixty-three out of 91 eligible participants with fluctuating PD (46% men, average age 66) had predefined sufficient adPMD datasets (>70% of half-hour periods) from 2 consecutive days. 92% of per-protocol assessments were completed. adPMD monitoring of daily times in motor states showed moderate validity for Off and Dyskinetic state (ICC = 0.43-0.51), while inter-rating methods agreements on half-hour-level can be characterized as poor (median Cohen's κ = 0.13-0.21). Individualization of adPMD thresholds for transferring accelerometer data into diary categories improved temporal agreements up to moderate level for Dyskinetic state detection (median Cohen's κ = 0.25-0.41). Here we report that adPMD real-world-monitoring captures daily times in Off and Dyskinetic state in advanced PD with moderate validities, while temporal agreement of adPMD and clinical observer diary data is limited.
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6.
  • Löhle, Matthias, et al. (författare)
  • Validation of the PD home diary for assessment of motor fluctuations in advanced Parkinson's disease
  • 2022
  • Ingår i: npj Parkinson's Disease. - : Springer Science and Business Media LLC. - 2373-8057. ; 8:1
  • Tidskriftsartikel (refereegranskat)abstract
    • The Parkinson's disease (PD) home diary is frequently used in clinical trials to measure efficacy of medical treatments for motor fluctuations in advanced PD. This prospective study in fluctuating PD patients examines the validity of the diary for quantification of motor states in comparison to direct clinical observation. 51 patients (median age: 65 years, disease duration: 11 years) completed the diary half-hourly for two consecutive days and were simultaneously rated by an experienced observer, who independently evaluated motor states half-hourly throughout daytime. Overall agreement (Cohen's kappa) between patient and observer diary entries was 59.8% (0.387). Patients documented more On without dyskinesia (52.3% vs. 38.9%, P < 0.001) and less On with dyskinesia (21.5% vs. 34.2%, P < 0.001), whereas proportions for Off intervals were not different between patient and observer diaries (26.2% vs. 27.0%, P = 0.97). Temporal agreement between diary ratings was unsatisfactory, particularly for On with dyskinesia. Taken together, our study suggests that the PD home diary only inadequately reflects actual motor states compared to direct clinical observation.
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7.
  • Timpka, Jonathan, et al. (författare)
  • Objective Observer vs. Patient Motor State Assessments Using the PD Home Diary in Advanced Parkinsons Disease
  • 2022
  • Ingår i: Frontiers in Neurology. - : Frontiers Media SA. - 1664-2295. ; 13
  • Tidskriftsartikel (refereegranskat)abstract
    • Background: The Parkinson Disease (PD) Home Diary (HD) is a commonly used clinical outcome measure, but it has not been extensively compared to direct assessments by experienced observers. Objective: Validation of patient-reported HD by investigating the agreement between motor state assessments by patients and observers. Methods: This observational study included patients with PD and motor fluctuations. Observers were physicians or research nurses. Patients completed a screening visit, one day of diary ratings at home, and then two days of ratings on-site during which patients and observers simultaneously judged the participants motor state. Results: Observers and 40 patients completed 1,288 pairs of half-hourly blinded motor state assessments. There were significant differences between observer and patient ratings (P < 0.001) and the temporal agreement was poor (Cohens kappa = 0.358). The agreement between patient and observer ratings was 71.1% for observed "On without dyskinesia", 57.3% for observed "Off", and 49.4% for observed "On with dyskinesia". Daily times spent in the three motor states as aggregated diary data showed fair to excellent reliability with intraclass coefficient values ranging from 0.45 to 0.52 for "On" and 0.77 for "Off". Conclusion: There were significant differences between observer and patient ratings. Patients and observers generally agreed on when the patients was in the "On" state (with or without dyskinesia). Patient ratings on the hour level seem to be influenced by other aspects of the patients experience than the observed motor state, but assessment of daily time spent in the different motor state provides reasonable reliability.
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8.
  • Aad, G., et al. (författare)
  • 2013
  • Tidskriftsartikel (refereegranskat)
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9.
  • Aad, G., et al. (författare)
  • 2012
  • Ingår i: Journal of High Energy Physics. - 1029-8479 .- 1126-6708. ; :6
  • Tidskriftsartikel (refereegranskat)
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