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- Aleksic, J., et al.
(författare)
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Measurement of the Crab Nebula spectrum over three decades in energy with the MAGIC telescopes
- 2015
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Ingår i: Journal of High Energy Astrophysics. - : Elsevier BV. - 2214-4048 .- 2214-4056. ; 5-6, s. 30-38
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Tidskriftsartikel (refereegranskat)abstract
- The MAGIC stereoscopic system collected 69 hours of Crab Nebula data between October 2009 and April 2011. Analysis of this data sample using the latest improvements in the MAGIC stereoscopic software provided an unprecedented precision of spectral and night-by-night light curve determination at gamma rays. We derived a differential spectrum with a single instrument from 50 GeV up to almost 30 TeV with 5 bins per energy decade. At low energies, MAGIC results, combined with Fermi-LAT data, show a flat and broad Inverse Compton peak. The overall fit to the data between 1 GeV and 30 TeV is not well described by a log-parabola function. We find that a modified log-parabola function with an exponent of 2.5 instead of 2 provides a good description of the data (chi(2)(red) = 35/26). Using systematic uncertainties of the MAGIC and Fermi-LAT measurements we determine the position of the Inverse Compton peak to be at (53 +/- 3(stat)+ 31(syst)-13(syst)) GeV, which is the most precise estimation up to date and is dominated by the systematic effects. There is no hint of the integral flux variability on daily scales at energies above 300 GeV when systematic uncertainties are included in the flux measurement. We consider three state-of-the-art theoretical models to describe the overall spectral energy distribution of the Crab Nebula. The constant B-field model cannot satisfactorily reproduce the VHE spectral measurements presented in this work, having particular difficulty reproducing the broadness of the observed IC peak. Most probably this implies that the assumption of the homogeneity of the magnetic field inside the nebula is incorrect. On the other hand, the time-dependent 1D spectral model provides a good fit of the new VHE results when considering a 80 mu G magnetic field. However, it fails to match the data when including the morphology of the nebula at lower wavelengths.
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| 2. |
- Grady, C., et al.
(författare)
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The outer disks of Herbig stars from the UV to NIR
- 2015
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Ingår i: Astrophysics and Space Science. - : Springer Science and Business Media LLC. - 0004-640X .- 1572-946X. ; 355:2, s. 253-266
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Forskningsöversikt (refereegranskat)abstract
- Spatially-resolved imaging of Herbig stars and related objects began with HST, but intensified with commissioning of high-contrast imagers on 8-m class telescopes. The bulk of the data taken from the ground have been polarized intensity imagery at H-band, with the majority of the sources observed as part of the Strategic Exploration of Exoplanets and Disks with Subaru (SEEDS) survey. Sufficiently many systems have been imaged that we discuss disk properties in scattered, polarized light in terms of groups defined by the IR spectral energy distribution. We find novel phenomena in many of the disks, including spiral density waves, and discuss the disks in terms of clearing mechanisms. Some of the disks have sufficient data to map the dust and gas components, including water ice dissociation products.
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| 3. |
- Cung, T. -T., et al.
(författare)
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Cyclosporine before PCI in Patients with Acute Myocardial Infarction
- 2015
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Ingår i: New England Journal of Medicine. - 0028-4793. ; 373:11, s. 1021-1031
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Tidskriftsartikel (refereegranskat)abstract
- BACKGROUND Experimental and clinical evidence suggests that cyclosporine may attenuate reperfusion injury and reduce myocardial infarct size. We aimed to test whether cyclosporine would improve clinical outcomes and prevent adverse left ventricular remodeling. METHODS In a multicenter, double-blind, randomized trial, we assigned 970 patients with an acute anterior ST-segment elevation myocardial infarction (STEMI) who were undergoing percutaneous coronary intervention (PCI) within 12 hours after symptom onset and who had complete occlusion of the culprit coronary artery to receive a bolus injection of cyclosporine (administered intravenously at a dose of 2.5 mg per kilogram of body weight) or matching placebo before coronary recanalization. The primary outcome was a composite of death from any cause, worsening of heart failure during the initial hospitalization, rehospitalization for heart failure, or adverse left ventricular remodeling at 1 year. Adverse left ventricular remodeling was defined as an increase of 15% or more in the left ventricular end-diastolic volume. RESULTS A total of 395 patients in the cyclosporine group and 396 in the placebo group received the assigned study drug and had data that could be evaluated for the primary outcome at 1 year. The rate of the primary outcome was 59.0% in the cyclosporine group and 58.1% in the control group (odds ratio, 1.04; 95% confidence interval, 0.78 to 1.39; P = 0.77). Cyclosporine did not reduce the incidence of the separate clinical components of the primary outcome or other events, including recurrent infarction, unstable angina, and stroke. No significant difference in the safety profile was observed between the two treatment groups. CONCLUSIONS In patients with anterior STEMI who had been referred for primary PCI, intravenous cyclosporine did not result in better clinical outcomes than those with placebo and did not prevent adverse left ventricular remodeling at 1 year. (Funded by the French Ministry of Health and NeuroVive Pharmaceutical; CIRCUS ClinicalTrials.gov number, NCT01502774; EudraCT number, 2009-013713-99.)
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