Formation of Warped Disks by Galactic Fly-by Encounters. I. Stellar Disks

Warped disks are almost ubiquitous among spiral galaxies. Here we revisit and test the `fly-by scenario' of warp formation, in which impulsive encounters between galaxies are responsible for warped disks. Based on N-body simulations, we investigate the morphological and kinematical evolution of the stellar component of disks when galaxies undergo fly-by interactions with adjacent dark matter halos. We find that the so-called `S'-shaped warps can be excited by fly-bys and sustained for even up to a few billion years, and that this scenario provides a cohesive explanation for several key observations. We show that disk warp properties are governed primarily by the following three parameters; (1) the impact parameter, i.e., the minimum distance between two halos, (2) the mass ratio between two halos, and (3) the incident angle of the fly-by perturber. The warp angle is tied up with all three parameters, yet the warp lifetime is particularly sensitive to the incident angle of the perturber. Interestingly, the modeled S-shaped warps are often non-symmetric depending on the incident angle. We speculate that the puzzling U- and L-shaped warps are geometrically superimposed S-types produced by successive fly-bys with different incident angles, including multiple interactions with a satellite on a highly elongated orbit.Comment: 16 pages, 13 figures, 3 tables. Accepted for publication in Ap

Hemorrhagic pericarditis with cardiac tamponade after percutaneous coronary intervention associated with the use of abciximab

Glycoprotein (GP) IIb/IIIa inhibitors, such as abciximab, are used as adjunctive therapy for percutaneous coronary intervention (PCI) in high-risk non-ST-elevation myocardial infarction (NSTEMI) and in ST-elevation myocardial infarction (STEMI), although their effects when used for STEMI are less clear. As the use of GP IIb/IIIa inhibitors becomes more widespread, determining the risks associated with them becomes more important. The major risks associated with the use of GP IIb/IIIa inhibitors are the potential for major bleeding and thrombocytopenia. This is the first reported case in Korea of hemorrhagic pericarditis resulting in cardiac tamponade associated with the use of abciximab, a commonly used GP Ilb/IIa inhibitor, following PCI

A new technique for Nd:YAG laser posterior capsulotomy

AIM: To investigate the effects of a new opening pattern in neodymium:yttrium-aluminum-garnet (Nd:YAG) laser posterior capsulotomy on visual function.METHODS: This technique was conducted along a circular pattern. The energy ranged between 0.8 and 1.2 mJ/pulse was consumed and mean total energy levels were 74±21 mJ (mean±standard deviation:SD, from 40 to 167) and laser shots aimed at 150 µm away behind a datum point and went along an imaginary line which extends 0.5 mm inside from optic margin and into the circular en bloc pattern. Vitreous stands were attached with fragment and then they were cut off by the laser after circular application. The circular fragment was completely separated from vitreous, and then this fragment was quickly sunk in intravitreal space.RESULTS: The follow-up period ranges from at least a week to 40mo, making 15.8mo on average. The procedural outcome showed 96% (74 eyes out of the 77 eyes) enhancement in patients’ visual acuity. Cystoid macular edema or retinal detachment was not observed in any of the patients during follow-up periods.CONCLUSION: This new technique is expected to improve the weaknesses that the conventional procedures have by adding the process to cut off vitreous stands attached with the fragment by the laser to the circular application