Related papers: cond-mat/9806011

This paper has been withdrawn by the author.

This paper has been withdrawn.

The paper has been withdrawn by the author.

This paper has been withdrawn.

This paper has been withdrawn by the authors due to its publication

This paper is withdrawn by the authors

This paper is withdrawn by the authors.

This paper has been withdrawn.

This paper has been withdrawn.

This paper has been withdrawn by the authors.

This paper has been withdrawn by the authors due to numerical problems to get viable results.

This paper has been withdrawn.

This paper has been withdrawn by the authors.

This paper has been withdrawn by the author

This paper has been withdrawn by the author [arXiv admin].

This paper has been withdrawn

This paper has been withdrawn by the author.

This paper has been withdrawn

This paper has been withdrawn, pending revision of the main conclusion, in the light of the criticism of cond-mat/0302043.

This paper has been withdrawn by the author.