V751 Cyg and V Sge as transient supersoft X-ray sources

I review the observational evidence for luminous, soft X-ray emission during optical low-states in the two cataclysmic variables V751 Cyg and V Sge, and discuss the possible link to the canonical supersoft X-ray sources.Comment: 6 pages with newarcrc.sty; inv. talk given at the 60th birthday Symp. in honour of Brian Warner, Oxford, April 1999, to appear in New Astronomy Reviews (Elsevier), eds. P. Charles, A. King, D. O'Donoghue; also available from http://www.aip.de/~jcg/publis.htm

Gamma-ray bursts with ROSAT

I review the use of ROSAT over the last years for the investigation of well localized gamma-ray burst (GRB) error boxes. In particular, I cover (i) the systematic study of several dozens of IPN locations using the ROSAT All-Sky-Survey data, (ii) results of deep ROSAT pointings of selected small GRB error boxes, (iii) the attempts for and results of quick follow-up observations after GRB events including the three GRBs localized with BeppoSAX, (iv) the correlation of GRB locations with serendipitous ROSAT pointings and (v) the search for X-ray flashes in the database of pointed ROSAT observations.Comment: Invited talk at the workshop on "All-sky X-ray observations in the next decade", held at RIKEN, Tokyo, March 3-5, 1997; 6 pages incl. 3 ps-figures, plus workshop style file

Density correlators in a self-similar cascade

Multivariate density moments (correlators) of arbitrary order are obtained for the multiplicative self-similar cascade. This result is based on the calculation by Greiner, Eggers and Lipa (reference [1]) where the correlators of the logarithms of the particle densities have been obtained. The density correlators, more suitable for comparison with multiparticle data, appear to have even simpler form than those obtained in [1].Comment: 9 pages, 3 figures, uses epsfig.st