1. Khoury College of Computer Sciences, Northeastern University, Boston, Massachusetts 02115, United States
2. Institute of Mathematics, University of Wrocław, Wrocław 50-384, Poland
3. Department of Pathology, University of Michigan, Ann Arbor, Michigan 48109, United States
4. Department of Chemistry and Chemical Biology, Barnett Institute of Biological and Chemical Analysis, Northeastern University, Boston, Massachusetts 02115, United States
5. Departments of Microchemistry, Proteomics & Lipidomics, Genentech, South San Francisco, California 94080, United States