  This paper has been superseded to a great extent by the following:
  Paper: math.AG/0511558 Title: The Neron-Severi group of a proper seminormal
complex variety Authors: L. Barbieri-Viale, A. Rosenschon & V. Srinivas
  Paper: math.AG/0102150 Title: Deligne's Conjecture on 1-Motives Authors: Luca
Barbieri-Viale, Andreas Rosenschon, Morihiko Saito Journal-ref: Ann. of Math.
(2), Vol. 158 (2003), no. 2, 593--633
