| 1. |
- Demetris, A J, et al.
(författare)
-
2016 Comprehensive Update of the Banff Working Group on Liver Allograft Pathology: Introduction of Antibody-Mediated Rejection.
- 2016
-
Ingår i: American journal of transplantation : official journal of the American Society of Transplantation and the American Society of Transplant Surgeons. - : Elsevier BV. - 1600-6143. ; 16:10, s. 2816-2835
-
Tidskriftsartikel (refereegranskat)abstract
- The Banff Working Group on Liver Allograft Pathology reviewed and discussed literature evidence regarding antibody-mediated liver allograft rejection at the 11th (Paris, France, June 5-10, 2011), 12th (Comandatuba, Brazil, August 19-23, 2013), and 13th (Vancouver, British Columbia, Canada, October 5-10, 2015) meetings of the Banff Conference on Allograft Pathology. Discussion continued online. The primary goal was to introduce guidelines and consensus criteria for the diagnosis of liver allograft antibody-mediated rejection and provide a comprehensive update of all Banff Schema recommendations. Included are new recommendations for complement component 4d tissue staining and interpretation, staging liver allograft fibrosis, and findings related to immunosuppression minimization. In an effort to create a single reference document, previous unchanged criteria are also included.
|
|
| 2. |
- Ryu, Y. -H., et al.
(författare)
-
OGLE-2016-BLG-1190Lb : The First Spitzer Bulge Planet Lies Near the Planet/Brown-dwarf Boundary
- 2018
-
Ingår i: Astronomical Journal. - : American Astronomical Society. - 0004-6256 .- 1538-3881. ; 155:1
-
Tidskriftsartikel (refereegranskat)abstract
- We report the discovery of OGLE-2016-BLG-1190Lb, which is likely to be the first Spitzer microlensing planet in the Galactic bulge/ bar, an assignation that can be confirmed by two epochs of high-resolution imaging of the combined source-lens baseline object. The planet's mass, M-p = 13.4 +/- 0.9 M-J, places it right at the deuteriumburning limit, i. e., the conventional boundary between planets and brown dwarfs. Its existence raises the question of whether such objects are really planets (formed within the disks of their hosts) or failed stars (lowmass objects formed by gas fragmentation). This question may ultimately be addressed by comparing disk and bulge/bar planets, which is a goal of the Spitzer microlens program. The host is a G dwarf, M-host = 0.89. +/- 0.07 M-circle dot, and the planet has a semimajor axis a similar to 2.0 au. We use Kepler K2 Campaign 9 microlensing data to break the lens-mass degeneracy that generically impacts parallax solutions from Earth-Spitzer observations alone, which is the first successful application of this approach. The microlensing data, derived primarily from near-continuous, ultradense survey observations from OGLE, MOA, and three KMTNet telescopes, contain more orbital information than for any previous microlensing planet, but not quite enough to accurately specify the full orbit. However, these data do permit the first rigorous test of microlensing orbital-motion measurements, which are typically derived from data taken over < 1% of an orbital period.
|
|
| 3. |
- Bensby, T., et al.
(författare)
-
Chemical evolution of the Galactic bulge as traced by microlensed dwarf and subgiant stars : VI. Age and abundance structure of the stellar populations in the central sub-kpc of the Milky Way
- 2017
-
Ingår i: Astronomy and Astrophysics. - : EDP Sciences. - 0004-6361 .- 1432-0746. ; 605
-
Tidskriftsartikel (refereegranskat)abstract
- We present a detailed elemental abundance study of 90 F and G dwarf, turn-off, and subgiant stars in the Galactic bulge. Based on high-resolution spectra acquired during gravitational microlensing events, stellar ages and abundances for 11 elements (Na, Mg, Al, Si, Ca, Ti, Cr, Fe, Zn, Y and Ba) have been determined. Four main findings are presented: (1) a wide metallicity distribution with distinct peaks at [Fe/H] = -1.09, -0.63, -0.20, + 0.12, + 0.41; (2) a highfraction of intermediate-age to young stars where at [Fe/H] > 0 more than 35% are younger than 8 Gyr, and for [Fe/H] ≲-0.5 most stars are 10 Gyr or older; (3) several episodes of significant star formation in the bulge has been identified: 3, 6, 8, and 11 Gyr ago; (4) tentatively the "knee" in the α-element abundance trends of the sub-solar metallicity bulge is located at a slightly higher [Fe/H] than in the local thick disk. These findings show that the Galactic bulge has complex age and abundance properties that appear to be tightly connected to the main Galactic stellar populations. In particular, the peaks in the metallicity distribution, the star formation episodes, and the abundance trends, show similarities with the properties of the Galactic thin and thick disks. At the same time, the star formation rate appears to have been slightly faster in the bulge than in the local thick disk, which most likely is an indication of the denser stellar environment closer to the Galactic centre. There are also additional components not seen outside the bulge region, and that most likely can be associated with the Galactic bar. Our results strengthen the observational evidence that support the idea of a secular origin for the Galactic bulge, formed out of the other main Galactic stellar populations present in the central regions of our Galaxy. Additionally, our analysis of this enlarged sample suggests that the (V-I)0 colour of the bulge red clump should be revised to 1.09.
|
|
| 4. |
- Han, C., et al.
(författare)
-
OGLE-2017-BLG-0329L : A Microlensing Binary Characterized with Dramatically Enhanced Precision Using Data from Space-based Observations
- 2018
-
Ingår i: Astrophysical Journal. - : American Astronomical Society. - 0004-637X .- 1538-4357. ; 859:2
-
Tidskriftsartikel (refereegranskat)abstract
- Mass measurements of gravitational microlenses require one to determine the microlens parallax pE, but precise pE measurement, in many cases, is hampered due to the subtlety of the microlens-parallax signal combined with the difficulty of distinguishing the signal from those induced by other higher-order effects. In this work, we present the analysis of the binary-lens event OGLE-2017-BLG-0329, for which pi(E) is measured with a dramatically improved precision using additional data from space-based Spitzer observations. We find that while the parallax model based on the ground-based data cannot be distinguished from a zero-pi(E) model at the 2 sigma level, the addition of the Spitzer data enables us to identify two classes of solutions, each composed of a pair of solutions according to the well-known ecliptic degeneracy. It is found that the space-based data reduce the measurement uncertainties of the north and east components of the microlens-parallax vector pE by factors similar to 18 and similar to 4, respectively. With the measured microlens parallax combined with the angular Einstein radius measured from the resolved caustic crossings, we find that the lens is composed of a binary with component masses of either (M-1, M-2) similar to (1.1, 0.8) M-circle dot or similar to(0.4, 0.3) M-circle dot according to the two solution classes. The first solution is significantly favored but the second cannot be securely ruled out based on the microlensing data alone. However, the degeneracy can be resolved from adaptive optics observations taken similar to 10 years after the event.
|
|
| 5. |
- Sumi, T., et al.
(författare)
-
The first Neptune analog or super-earth with a Neptune-like orbit : MOA-2013-BLG-605LB
- 2016
-
Ingår i: Astrophysical Journal. - 0004-637X. ; 825:2
-
Tidskriftsartikel (refereegranskat)abstract
- We present the discovery of the first Neptune analog exoplanet or super-Earth with a Neptune-like orbit, MOA-2013-BLG-605Lb. This planet has a mass similar to that of Neptune or a super-Earth and it orbits at 9 ∼ 14 times the expected position of the snow line, a snow, which is similar to Neptune's separation of 11 a snow from the Sun. The planet/host-star mass ratio is q = (3.6 ± 0.7) × 10-4 and the projected separation normalized by the Einstein radius is s = 2.39 ± 0.05. There are three degenerate physical solutions and two of these are due to a new type of degeneracy in the microlensing parallax parameters, which we designate "the wide degeneracy." The three models have (i) a Neptune-mass planet with a mass of Mp = 21-7 +6M⊕ orbiting a low-mass M-dwarf with a mass of Mh = 0.19-0.06 +0.05M⊙, (ii) a mini-Neptune with Mp = 7.9-1.2 +1.8M⊕ orbiting a brown dwarf host with Mh = 0.068-0.011 +0.019M⊙, and (iii) a super-Earth with Mp = 3.2-0.3 +0.5MM⊕ orbiting a low-mass brown dwarf host with Mh = 0.025-0.0004 +0.005M⊙, which is slightly favored. The 3D planet-host separations are 4.6-1.2 +4.7au, 2.1-0.2 +1.0au, and 0.94-0.02 +0.67au, which are 8.9-1.4 +10.5, 12-1 +7, or 14-1 +11 times larger than a snow for these models, respectively. Keck adaptive optics observations confirm that the lens is faint. This discovery suggests that low-mass planets with Neptune-like orbits are common. Therefore processes similar to the one that formed Neptune in our own solar system or cold super-Earths may be common in other solar systems.
|
|
| 6. |
- Terreran, G., et al.
(författare)
-
Hydrogen-rich supernovae beyond the neutrino-driven core-collapse paradigm
- 2017
-
Ingår i: Nature Astronomy. - : Springer Science and Business Media LLC. - 2397-3366. ; 1:10, s. 713-720
-
Tidskriftsartikel (refereegranskat)abstract
- Type II supernovae are the final stage of massive stars (above 8 M-circle dot) which retain part of their hydrogen-rich envelope at the moment of explosion. They typically eject up to 15 M-circle dot of material, with peak magnitudes of -17.5 mag and energies in the order of 10(51) erg, which can be explained by neutrino-driven explosions and neutron star formation. Here, we present our study of OGLE-2014-SN-073, one of the brightest type II supernovae ever discovered, with an unusually broad lightcurve combined with high ejecta velocities. From our hydrodynamical modelling, we infer a remarkable ejecta mass of 60(-16)(+42) M-circle dot and a relatively high explosion energy of 12.4(-5.9)(+13.0) x 10(51) erg. We show that this object belongs, along with a very small number of other hydrogen-rich supernovae, to an energy regime that is not explained by standard core-collapse neutrino-driven explosions. We compare the quantities inferred by the hydrodynamical modelling with the expectations of various exploding scenarios and attempt to explain the high energy and luminosity released. We find some qualitative similarities with pair-instability supernovae, although the prompt injection of energy by a magnetar seems to be a viable alternative explanation for such an extreme event.
|
|
| 7. |
- Udalski, A., et al.
(författare)
-
OGLE-2017-BLG-1434Lb : Eighth q < 1 x 10(-4) Mass-Ratio Microlens Planet Confirms Turnover in Planet Mass-Ratio Function
- 2018
-
Ingår i: Acta Astronomica. - 0001-5237. ; 68:1, s. 1-42
-
Tidskriftsartikel (refereegranskat)abstract
- We report the discovery of a cold Super-Earth planet (m(p) = 4.4 +/- 0.5 M-circle plus) orbiting a low-mass (M = 0.23 +/- 0.03 M-circle dot) M dwarf at projected separation a(perpendicular to) l = 1.18 +/- 0.10 a.u., i.e., about 1.9 times the distance the snow line. The system is quite nearby for a microlensing planet, D-L = 0.86 +/- 0.09 kpc. Indeed, it was the large lens-source relative parallax pi(rel) = 1.0 mas (combined with the low mass M) that gave rise to the large, and thus well-measured, microlens parallax pi(E) proportional to (pi(rel)/M)(1)(/2) that enabled these precise measurements. OGLE-2017-BLG-1434Lb is the eighth microlensing planet with planet-host mass ratio q < 1 x 10(-4). We apply a new planet-detection sensitivity method, which is a variant of V/V-max, to seven of these eight planets to derive the mass-ratio function in this regime. We find dN/ d lnq proportional to q(P) , with p =1.05(-0.68)(+0.78), which confirms the turnover in the mass function found by Suzuki et al. relative to the power law of opposite sign n = -0.93 +/- 0.13 at higher mass ratios q greater than or similar to 2 x 10(-4). We combine our result with that of Suzuki et al. to obtain p = 0.73(-0.34)(+0.42.)
|
|
| 8. |
- Dokhane, A., et al.
(författare)
-
Analysis of Oskarshamn-2 stability event using TRACE/SIMULATE-3K and comparison to TRACE/PARCS and SIMULATE-3K stand-alone
- 2017
-
Ingår i: Annals of Nuclear Energy. - : Elsevier. - 0306-4549 .- 1873-2100. ; 102, s. 190-199
-
Tidskriftsartikel (refereegranskat)abstract
- With the goal to enhance the capability to perform best-estimate simulations of Light Water Reactors (LWRs) transients, with strong coupling between core neutronics and plant thermal-hydraulic, a coupling between TRACE and SIMULATE-3K (TS3K) was developed in collaboration between PSI and Studsvik for analyses involving interactions between system and core. In order to verify the coupling scheme and the coupled code capabilities to simulate complex transients, the OECD/NEA Oskarshmn-2 (O-2) Stability benchmark was modeled with the coupled code TS3K. The main goal of this paper is to present TS3K analyses of the Oskarshamn-2 stability event, noting that this constitutes the first reported assessment of this code system for a BWR stability problem. A systematic analysis is carried out using different time-space discretization schemes in order to identify an optimized methodology to simulate correctly the O-2 stability event. In this context, the TS3K results are compared to the available benchmark data both for steady-state and transient conditions. The results show that using a refined model in space and time, the TS3K model can successfully capture the entire behavior of the transient qualitatively, i.e. onset of the instability with growing oscillation amplitudes, as well as quantitatively, i.e. Decay Ratio and resonance frequency. In addition, the results are compared also to those obtained using TRACE/PARCS and S3K stand-alone, which allows a systematic comparison between different codes.
|
|
| 9. |
- Gromadzki, M., et al.
(författare)
-
Discovery and follow-up of the unusual nuclear transient OGLE17aaj
- 2019
-
Ingår i: Astronomy and Astrophysics. - : EDP Sciences. - 0004-6361 .- 1432-0746. ; 622
-
Tidskriftsartikel (refereegranskat)abstract
- Aims. We report on the discovery and follow-up of a peculiar transient, OGLE17aaj, which occurred in the nucleus of a weakly active galaxy. We investigate whether it can be interpreted as a new candidate for a tidal disruption event (TDE).Methods. We present the OGLE-IV light curve that covers the slow 60-day-long rise to maximum along with photometric, spectro-scopic, and X-ray follow-up during the first year.Results. OGLE17aaj is a nuclear transient exhibiting some properties similar to previously found TDEs, including a long rise time, lack of colour-temperature evolution, and high black-body temperature. On the other hand, its narrow emission lines and slow post-peak evolution are different from previously observed TDEs. Its spectrum and light-curve evolution is similar to F01004-2237 and AT 2017bgt. Signatures of historical low-level nuclear variability suggest that OGLE17aaj may instead be related to a new type of accretion event in active super-massive black holes.
|
|
| 10. |
- Pazsit, Imre, 1948, et al.
(författare)
-
The stability of boiling water reactors as a catastrophe phenomenon
- 2015
-
Ingår i: Mathematics and Computations, Supercomputing in Nuclear Applications and Monte Carlo International Conference, M and C+SNA+MC 2015, Nashville, United States, 19-23 April 2015. - 9781510808041 ; 1, s. 763-774
-
Konferensbidrag (refereegranskat)abstract
- The stability of boiling water reactors (BWRs) is revisited in terms of catastrophe theory. The hypothesis is proposed that the stability parameter (decay ratio) of a complex, many-variable non-linear system might obey a cusp catastrophe. The incentive for this surmise comes from indications in real measurements that in certain cases the decay ratio appears to behave discontinuously and might show a hysteresis as a function of the control parameters reactor power and coolant flow. Such observations can be explained by a phenomenological catastrophe model suggested in this article. Since a cusp-type behaviour implies that the decay ratio is many-valued in a certain region of the power-flow map, a mechanism is suggested how a Hopf bifurcation with multiplicative noise can lead to such a behaviour.
|
|
