... Here we present our first results of a study of the neutral hydrogen gas (HI) in the southern spiral galaxy NGC 253 with the Australia Telescope Compact Array . ... Several peculiar features have been found. ... Similar features have been found in other starburst galaxies like M82, NGC 1808 and NGC 4945 and are interpreted in terms of bar-induced gas dynamics and star formation. Keywords. galaxies: individual (NGC 253) - galaxies: active - galaxies: ISM - galaxies: kinematics and dynamics. ...

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