5 research outputs found
Young Massive Clusters in Non-Interacting Galaxies
Young star clusters with masses well in excess of 100.000 Msun have been
observed not only in merger galaxies and large-scale starbursts, but also in
fairly normal, undisturbed spiral and irregular galaxies. Here we present
virial mass estimates for a sample of 7 such clusters and show that the derived
mass-to-light ratios are consistent with "normal" Kroupa-type stellar mass
distributions.Comment: 4 pages, 1 figure, to appear in "Starbursts from 30 Doradus to Lyman
Break Galaxies'', eds. R. de Grijs, R. M. Gonzalez Delgad
Development of a tight-binding potential for bcc-Zr. Application to the study of vibrational properties
We present a tight-binding potential based on the moment expansion of the
density of states, which includes up to the fifth moment. The potential is
fitted to bcc and hcp Zr and it is applied to the computation of vibrational
properties of bcc-Zr. In particular, we compute the isothermal elastic
constants in the temperature range 1200K < T < 2000K by means of standard Monte
Carlo simulation techniques. The agreement with experimental results is
satisfactory, especially in the case of the stability of the lattice with
respect to the shear associated with C'. However, the temperature decrease of
the Cauchy pressure is not reproduced. The T=0K phonon frequencies of bcc-Zr
are also computed. The potential predicts several instabilities of the bcc
structure, and a crossing of the longitudinal and transverse modes in the (001)
direction. This is in agreement with recent ab initio calculations in Sc, Ti,
Hf, and La.Comment: 14 pages, 6 tables, 4 figures, revtex; the kinetic term of the
isothermal elastic constants has been corrected (Eq. (4.1), Table VI and
Figure 4
Predictors of sudden cardiac death after Mustard or Senning repair for transposition of the great arteries.
Item does not contain fulltextOBJECTIVES: The goal of this research was to identify predictors for sudden death (SD) in patients with transposition of the great arteries (TGA) who have undergone atrial inflow repair. BACKGROUND: Sudden death is the most common cause of late death after atrial inflow repair of TGA. Little is known about the predictors of SD. METHODS: This was a retrospective, multicenter, case-controlled study. We identified 47 patients after Mustard's or Senning's operation who experienced an SD event (34 SD, 13 near-miss SD). Each patient was matched with two controls with the same operation, but without an SD event. Information on numerous variables before the event was obtained and compared with controls at the same time frame. RESULTS: Presence of symptoms of arrhythmia or heart failure at most recent follow-up and history of documented arrhythmia (atrial flutter [AFL]/atrial fibrillation [AF]) were found to increase the risk of SD. Electrocardiogram (ECG), chest X-ray, and Holter ECG findings were not predictive of SD. Neither medication nor pacing was found to be protective. Most SD events (81%) occurred during exercise. Ventricular tachycardia/ventricular fibrillation were the recorded rhythm during SD in 21 of 47 patients. CONCLUSIONS: Presence of symptoms and documented AFL/AF are the best predictors of SD in TGA patients. Patients with these findings should be further evaluated for risk of SD