Interactions and star formation activity in Wolf-Rayet galaxies ґ Angel R. Lґ ez-Sґ hez1 and Cґ op anc esar Esteban 1 2 2 CSIRO ATNF, Australia Angel.Lopez-Sanchez@csiro.au Instituto de Astrofґ isica de Canarias, Spain, cel@iac.es We present some global results of the PhD Thesis carried out by Lґ ezop Sґ hez (2006), in which a detailed morphological, photometrical and spectrosanc copical analysis of a sample of 20 Wolf-Rayet (WR) galaxies was realized. ...

metrologia The leap second: its history and possible future R. A. Nelson, D. D. McCarthy , S. Malys, J. Levine, B. Guinot, H. F. Fliegel , R. L. Beard and T. R. Bartholome w Abstract. This paper reviews the theoretica l motivatio n for the leap second in the context of the historica l evolutio n of time measurement . Th e periodic insertio n of a leap second step into th e scale of Coordinate d Universal Time (UTC) necessitates frequent changes in comple x timekeepin g systems an d is currentl y th e