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- Rossi, A., et al.
(författare)
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A blast from the infant Universe : The very high-z GRB210905A
- 2022
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Ingår i: Astronomy and Astrophysics. - : EDP Sciences. - 0004-6361 .- 1432-0746. ; 665
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Tidskriftsartikel (refereegranskat)abstract
- We present a detailed follow-up of the very energetic GRB 210905A at a high redshift of z = 6.312 and its luminous X-ray and optical afterglow. Following the detection by Swift and Konus-Wind, we obtained a photometric and spectroscopic follow-up in the optical and near-infrared (NIR), covering both the prompt and afterglow emission from a few minutes up to 20 Ms after burst. With an isotropic gamma-ray energy release of Eiso = 1.27−0.19+0.20 × 1054 erg, GRB 210905A lies in the top ∼7% of gamma-ray bursts (GRBs) in the Konus-Wind catalogue in terms of energy released. Its afterglow is among the most luminous ever observed, and, in particular, it is one of the most luminous in the optical at t ≳ 0.5 d in the rest frame. The afterglow starts with a shallow evolution that can be explained by energy injection, and it is followed by a steeper decay, while the spectral energy distribution is in agreement with slow cooling in a constant-density environment within the standard fireball theory. A jet break at ∼46.2 ± 16.3 d (6.3 ± 2.2 d rest-frame) has been observed in the X-ray light curve; however, it is hidden in the H band due to a constant contribution from the host galaxy and potentially from a foreground intervening galaxy. In particular, the host galaxy is only the fourth GRB host at z > 6 known to date. By assuming a number density n = 1 cm−3 and an efficiency η = 0.2, we derived a half-opening angle of 8.4 ° ±1.0°, which is the highest ever measured for a z ≳ 6 burst, but within the range covered by closer events. The resulting collimation-corrected gamma-ray energy release of ≃1 × 1052 erg is also among the highest ever measured. The moderately large half-opening angle argues against recent claims of an inverse dependence of the half-opening angle on the redshift. The total jet energy is likely too large to be sustained by a standard magnetar, and it suggests that the central engine of this burst was a newly formed black hole. Despite the outstanding energetics and luminosity of both GRB 210905A and its afterglow, we demonstrate that they are consistent within 2σ with those of less distant bursts, indicating that the powering mechanisms and progenitors do not evolve significantly with redshift.
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- Ferri, F., et al.
(författare)
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The Propensity of the Human Liver to Form Large Lipid Droplets Is Associated with PNPLA3 Polymorphism, Reduced INSIG1 and NPC1L1 Expression and Increased Fibrogenetic Capacity
- 2021
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Ingår i: International Journal of Molecular Sciences. - : MDPI AG. - 1661-6596 .- 1422-0067. ; 22:11
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Tidskriftsartikel (refereegranskat)abstract
- In nonalcoholic steatohepatitis animal models, an increased lipid droplet size in hepatocytes is associated with fibrogenesis. Hepatocytes with large droplet (Ld-MaS) or small droplet (Sd-MaS) macrovesicular steatosis may coexist in the human liver, but the factors associated with the predominance of one type over the other, including hepatic fibrogenic capacity, are unknown. In pre-ischemic liver biopsies from 225 consecutive liver transplant donors, we retrospectively counted hepatocytes with Ld-MaS and Sd-MaS and defined the predominant type of steatosis as involving >= 50% of steatotic hepatocytes. We analyzed a donor Patatin-like phospholipase domain-containing protein 3 (PNPLA3) rs738409 polymorphism, hepatic expression of proteins involved in lipid metabolism by RT-PCR, hepatic stellate cell (HSC) activation by alpha-SMA immunohistochemistry and, one year after transplantation, histological progression of fibrosis due to Hepatitis C Virus (HCV) recurrence. Seventy-four livers had no steatosis, and there were 98 and 53 with predominant Ld-MaS and Sd-MaS, respectively. In linear regression models, adjusted for many donor variables, the percentage of steatotic hepatocytes affected by Ld-MaS was inversely associated with hepatic expression of Insulin Induced Gene 1 (INSIG-1) and Niemann-Pick C1-Like 1 gene (NPC1L1) and directly with donor PNPLA3 variant M, HSC activation and progression of post-transplant fibrosis. In humans, Ld-MaS formation by hepatocytes is associated with abnormal PNPLA3-mediated lipolysis, downregulation of both the intracellular cholesterol sensor and cholesterol reabsorption from bile and increased hepatic fibrogenesis.
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- Schady, P., et al.
(författare)
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Comparing emission- and absorption-based gas-phase metallicities in GRB host galaxies at z =2-4 using JWST
- 2024
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Ingår i: Monthly notices of the Royal Astronomical Society. - 0035-8711 .- 1365-2966. ; 529:3, s. 2807-2831
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Tidskriftsartikel (refereegranskat)abstract
- Much of what is known of the chemical composition of the universe is based on emission line spectra from star-forming galaxies. Emission-based inferences are, nevertheless, model-dependent and they are dominated by light from luminous star-forming regions. An alternative and sensitive probe of the metallicity of galaxies is through absorption lines imprinted on the luminous afterglow spectra of long gamma ray bursts (GRBs) from neutral material within their host galaxy. We present results from a JWST/NIRSpec programme to investigate for the first time the relation between the metallicity of neutral gas probed in absorption by GRB afterglows and the metallicity of the star-forming regions for the same host galaxy sample. Using an initial sample of eight GRB host galaxies at z = 2.1–4.7, we find a tight relation between absorption and emission line metallicities when using the recently proposed ?^ metallicity diagnostic (±0.2 dex). This agreement implies a relatively chemically homogeneous multiphase interstellar medium and indicates that absorption and emission line probes can be directly compared. However, the relation is less clear when using other diagnostics, such as R23 and R3. We also find possible evidence of an elevated N/O ratio in the host galaxy of GRB 090323 at z = 4.7, consistent with what has been seen in other z > 4 galaxies. Ultimate confirmation of an enhanced N/O ratio and of the relation between absorption and emission line metallicities will require a more direct determination of the emission line metallicity via the detection of temperature-sensitive auroral lines in our GRB host galaxy sample.
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- Albshesh, Ahmad, et al.
(författare)
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Effectiveness of Third-Class Biologic Treatment in Crohn's Disease : A Multi-Center Retrospective Cohort Study
- 2021
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Ingår i: Journal of Clinical Medicine. - : MDPI. - 2077-0383. ; 10:13
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Tidskriftsartikel (refereegranskat)abstract
- Background: Multiple studies have described the effectiveness of ustekinumab (UST) and vedolizumab (VDZ) in patients with Crohn's disease (CD) failing anti- Tumor necrosis factors (TNFs); however, the effectiveness of VDZ or UST as a third-class biologic has not yet been described.Aims and Methods: In this retrospective multicenter cohort study, we aimed to investigate the effectiveness of VDZ and UST as a third-class biologic in patients with CD.Results: Two-hundred and four patients were included; 156/204 (76%) patients received VDZ as a second- and UST as a third-class therapy (group A); the remaining 48/204 (24%) patients received UST as a second- and VDZ as a third-class therapy (group B). At week 16-22, 87/156 (55.5%) patients and 27/48 (56.2%) in groups A and B, respectively, responded to treatment (p = 0.9); 41/156 (26.2%) and 15/48 (31.2%) were in clinical remission (p = 0.5). At week 52; 89/103 (86%) patients and 25/29 (86.2%) of the patients with available data had responded to third-class treatment in groups A and B, respectively (p = 0.9); 31/103 (30%) and 47/29 (24.1%) were in clinical remission (p = 0.5).Conclusion: Third-class biological therapy was effective in more than half of the patients with CD. No differences in effectiveness were detected between the use of VDZ and UST as a third-class agent.
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| 7. |
- Balliu, Enkeleda, PhD student, et al.
(författare)
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Single-frequency, pulsed Yb3+-doped multicomponent phosphate power fiber amplifier
- 2020
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Ingår i: Journal of Optics. - : Institute of Physics Publishing (IOPP). - 2040-8978 .- 2040-8986. ; 22:11
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Tidskriftsartikel (refereegranskat)abstract
- High-power, single-frequency, pulsed fiber amplifiers are required in light detection and ranging, coherent laser detection, and remote sensing applications to reach long range within a short acquisition time. However, the power-scaling of these amplifiers is limited by nonlinearities generated in the optical fibers, in particular by stimulated Brillouin scattering (SBS). In this regard, the use of multicomponent phosphate glasses maximizes the energy extraction and minimizes nonlinearities. Here, we present the development of a single-stage, hybrid, pulsed fiber amplifier using a custom-made multicomponent Yb-doped phosphate fiber. The performance of the phosphate fiber was compared to a commercial Yb-doped silica fiber. While the latter showed SBS limitation at nearly 6.5 kW for 40 cm length, the maximum achieved output peak power for the multicomponent Yb-doped phosphate fiber was 11.7 kW for 9 ns pulses using only 20 cm with no sign of SBS.
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| 8. |
- Rossi, Andrea, et al.
(författare)
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Left atrial structural and mechanical remodelling in heart failure with reduced ejection fraction
- 2021
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Ingår i: ESC Heart Failure. - : John Wiley & Sons. - 2055-5822. ; 8:6, s. 4751-4759
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Tidskriftsartikel (refereegranskat)abstract
- Aims: In patients with heart failure with reduced ejection fraction (HFrEF), an association between left atrial (LA) dilatation and dysfunction is expected, but the degree of coexistence of the two abnormalities and their relative prognostic role is not known.Methods and results: A total of 626 HFrEF patients formed the study population. All of them underwent a comprehensive echocardiographic evaluation. LA maximal volume was indexed to body surface area (LAVi); LA function was assessed using strain analysis during the reservoir phase: peak atrial longitudinal strain (PALS) analysis. Study primary endpoint was overall mortality or hospitalization for worsening heart failure. Four groups of patients were included in this study according to LAVi (≤34 or >34 mL/m2 ) and PALS (≤23% or >23%); 61 (10%) patients had normal LA volume and function (Group 1), 58 (9%) had LA dilatation but normal function (Group 2), 100 (16%) had normal volume but abnormal function (Group 3), and 407 (65%) had enlarged left atrium and abnormal function (Group 4). PALS was associated with primary endpoint in patients with both normal-size [Groups 1 and 3: hazard ratio (HR) 0.92, 95% confidence interval (CI) 0.88-0.96; P = 0.0006] and dilated left atria (Groups 2 and 4: HR 0.93, 95% CI 0.91-0.96; P < 0.0001). In contrast, LAVi was associated with the primary endpoint in patients with abnormal LA function (Groups 3 and 4: HR 1.018, 95% CI 1.011-1.024; P < 0.00001) but not in those with normal PALS (Groups 1 and 2: HR 1.023, 95% CI 0.99-1.057; P = 0.1).Conclusions: Left atrial dilatation and dysfunction frequently but not invariably coexist. PALS emerged as a significant prognostic parameter in HFrEF even in the absence of LA dilation.
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