| 1. |
- Acciari, V. A., et al.
(författare)
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Radio Imaging of the Very-High-Energy gamma-Ray Emission Region in the Central Engine of a Radio Galaxy
- 2009
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Ingår i: Science. - : American Association for the Advancement of Science (AAAS). - 0036-8075 .- 1095-9203. ; 325:5939, s. 444-448
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Tidskriftsartikel (refereegranskat)abstract
- The accretion of matter onto a massive black hole is believed to feed the relativistic plasma jets found in many active galactic nuclei (AGN). Although some AGN accelerate particles to energies exceeding 10(12) electron volts and are bright sources of very-high-energy (VHE) gamma-ray emission, it is not yet known where the VHE emission originates. Here we report on radio and VHE observations of the radio galaxy Messier 87, revealing a period of extremely strong VHE gamma-ray flares accompanied by a strong increase of the radio flux from its nucleus. These results imply that charged particles are accelerated to very high energies in the immediate vicinity of the black hole.
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| 2. |
- Aleksic, J., et al.
(författare)
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DETECTION OF VERY HIGH ENERGY gamma-RAY EMISSION FROM THE PERSEUS CLUSTER HEAD-TAIL GALAXY IC 310 BY THE MAGIC TELESCOPES
- 2010
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Ingår i: The Astrophysical Journal Letters. - 2041-8205. ; 723:2, s. l207-L212
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Tidskriftsartikel (refereegranskat)abstract
- We report on the detection with the MAGIC telescopes of very high energy (VHE) gamma-rays from IC 310, a head-tail radio galaxy in the Perseus galaxy cluster, observed during the interval 2008 November to 2010 February. The Fermi satellite has also detected this galaxy. The source is detected by MAGIC at a high statistical significance of 7.6 sigma in 20.6 hr of stereo data. The observed spectral energy distribution is flat with a differential spectral index of -2.00 +/- 0.14. The mean flux above 300 GeV, between 2009 October and 2010 February, (3.1 +/- 0.5) x 10(-12) cm(-2) s(-1), corresponds to (2.5 +/- 0.4)% of Crab Nebula units. Only an upper limit, of 1.9% of Crab Nebula units above 300 GeV, was obtained with the 2008 data. This, together with strong hints (>3 sigma) of flares in the middle of 2009 October and November, implies that the emission is variable. The MAGIC results favor a scenario with the VHE emission originating from the inner jet close to the central engine. More complicated models than a simple one-zone synchrotron self-Compton (SSC) scenario, e. g., multi-zone SSC, external Compton, or hadronic, may be required to explain the very flat spectrum and its extension over more than three orders of magnitude in energy.
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| 3. |
- Beumer, B. R., et al.
(författare)
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Impact of muscle mass on survival of patients with hepatocellular carcinoma after liver transplantation beyond the Milan criteria
- 2022
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Ingår i: Journal of Cachexia, Sarcopenia and Muscle. - : Wiley. - 2190-5991 .- 2190-6009. ; 13:5, s. 2373-2382
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Tidskriftsartikel (refereegranskat)abstract
- Background: Access to the liver transplant waitlist for patients with hepatocellular carcinoma (HCC) depends on tumour presentation, biology, and response to treatments. The Milan Criteria (MC) represent the benchmark for expanded criteria that incorporate additional prognostic factors. The purpose of this study was to determine the added value of skeletal muscle index (SMI) in HCC patients beyond the MC. Method: Patients with HCC that were transplanted beyond the MC were included in this retrospective multicentre study. SMI was quantified using the Computed Tomography (CT) within 3months prior to transplantation. Cox regression models were used to identify predictors of overall survival (OS). The discriminative performance of SMI extended Metroticket 2.0 and AFP models was also assessed. Results: Out of 889 patients transplanted outside the MC, 528 had a CT scan within 3months prior to liver transplantation (LT), of whom 176 (33%) were classified as sarcopenic. The median time between assessment of the SMI and LT was 1.8months (IQR: 0.77–2.67). The median follow-up period was 5.1 95% CI [4.7–5.5] years, with a total of 177 recorded deaths from any cause. In a linear regression model with SMI as the dependent variable, only male gender (8.55 95% CI [6.51–10.59], P<0.001) and body mass index (0.74 95% CI [0.59–0.89], P<0.001) were significant. Univariable survival analysis of patients with sarcopenia versus patients without sarcopenia showed a significant difference in OS (HR 1.44 95% CI [1.07−1.94], P=0.018). Also the SMI was significant (HR 0.98 95% CI [0.96–0.99], P=0.014). The survival difference between the lowest SMI quartile versus the highest SMI quartile was significant (log-rank: P=0.005) with 5year OS of 57% and 71%, respectively. Data from 423 patients, describing 139 deaths, was used for multivariate analysis. Both sarcopenia (HR 1.45 95% CI [1.02−2.05], P=0.036) and SMI were (HR 0.98 95% CI [0.95–0.99], P=0.035) significant. On the survival scale this translates to a 5year OS difference of 11% between sarcopenia and no sarcopenia. Whereas for SMI, this translates to a survival difference of 8% between first and third quartiles for both genders. Conclusions: Overall, we can conclude that higher muscle mass contributes to a better long-term survival. However, for individual patients, low muscle mass should not be considered an absolute contra-indication for LT as its discriminatory performance was limited.
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