**5. Acknowledgements**

This work was supported by the Office of Naval Research (ONR) and the Naval Surface Warfare Center (NSWC) at Indian Head, MD. The authors express their thanks to Mary Sherlock, Robert Raines, Tina Woodland and Philip Thomas for helpful discussions and for providing the samples.

#### **6. References**


Greene, W. H. (2003). *Econometric Analysis*, 5th edition, Prentice Hall,

