| 1. |
- Milisavljevic, Dan, et al.
(författare)
-
MULTI-WAVELENGTH OBSERVATIONS OF SUPERNOVA 2011ei : TIME-DEPENDENT CLASSIFICATION OF TYPE IIb AND Ib SUPERNOVAE AND IMPLICATIONS FOR THEIR PROGENITORS
- 2013
-
Ingår i: Astrophysical Journal. - 0004-637X .- 1538-4357. ; 767:1, s. 71-
-
Tidskriftsartikel (refereegranskat)abstract
- We present X-ray, UV/optical, and radio observations of the stripped-envelope, core-collapse supernova (SN) 2011ei, one of the least luminous SNe IIb or Ib observed to date. Our observations begin with a discovery within similar to 1 day of explosion and span several months afterward. Early optical spectra exhibit broad, Type II-like hydrogen Balmer profiles that subside rapidly and are replaced by Type Ib-like He-rich features on a timescale of one week. High-cadence monitoring of this transition suggests absorption attributable to a high-velocity (greater than or similar to 12,000 km s(-1)) H-rich shell, which is likely present in many Type Ib events. Radio observations imply a shock velocity of v approximate to 0.13 c and a progenitor star average mass-loss rate of (M) over dot approximate to 1.4 x 10(-5) M-circle dot yr(-1) (assuming wind velocity v(w) = 10(3) km s(-1)). This is consistent with independent constraints from deep X-ray observations with Swift-XRT and Chandra. Overall, the multi-wavelength properties of SN 2011ei are consistent with the explosion of a lower-mass (3-4 M-circle dot), compact (R-* less than or similar to 1 x 10(11) cm), He-core star. The star retained a thin hydrogen envelope at the time of explosion, and was embedded in an inhomogeneous circumstellar wind suggestive of modest episodic mass loss. We conclude that SN 2011ei's rapid spectral metamorphosis is indicative of time-dependent classifications that bias estimates of the relative explosion rates for Type IIb and Ib objects, and that important information about a progenitor star's evolutionary state and mass loss immediately prior to SN explosion can be inferred from timely multi-wavelength observations.
|
|
| 2. |
- Petraco, Ricardo, et al.
(författare)
-
Real-time use of instantaneous wave-free ratio: Results of the ADVISE in-practice: An international, multicenter evaluation of instantaneous wave-free ratio in clinical practice
- 2014
-
Ingår i: American Heart Journal. - : Elsevier BV. - 1097-6744 .- 0002-8703. ; 168:5, s. 739-748
-
Tidskriftsartikel (refereegranskat)abstract
- Objectives To evaluate the first experience of real-time instantaneous wave-free ratio (iFR) measurement by clinicians. Background The iFR is a new vasodilator-free index of coronary stenosis severity, calculated as a trans-lesion pressure ratio during a specific period of baseline diastole, when distal resistance is lowest and stable. Because all previous studies have calculated iFR offline, the feasibility of real-time iFR measurement has never been assessed. Methods Three hundred ninety-two stenoses with angiographically intermediate stenoses were included in this multicenter international analysis. Instantaneous wave free ratio and fractional flow reserve (FFR) were performed in real time on commercially available consoles. The classification agreement of coronary stenoses between iFR and FFR was calculated. Results Instantaneous wave-free ratio and FFR maintain a close level of diagnostic agreement when both are measured by clinicians in real time (for a clinical 0.80 FFR cutoff: area under the receiver operating characteristic curve [ROCAUC] 0.87, classification match 80%, and optimal iFR cutoff 0.90; for a ischemic 0.75 FFR cutoff: iFR ROCAUC 0.90, classification match 88%, and optimal iFR cutoff 0.85; if the FFR 0.75-0.80 gray zone is accounted for: ROCAUC 0.93, classification match 92%). When iFR and FFR are evaluated together in a hybrid decision-making strategy, 61% of the population is spared from vasodilator while maintaining a 94% overall agreement with FFR lesion classification. Conclusion When measured in real time, iFR maintains the close relationship to FFR reported in offline studies. These findings confirm the feasibility and reliability of real-time iFR calculation by clinicians.
|
|
