1 \chapter*
{Acknowledgments
}
6 First of all, I would like to thank to my supervisor, Prof. Nicolai
7 Petkov, for his careful guidance during my study years. He gave me the
8 opportunity to enroll as a Ph.D. student in the ``Ubbo Emmius''
9 programme at University of Groningen. From him I learned that
10 scientific endeavor means much more than conceiving nice algorithms
11 and implementing them as computer programs on the newest parallel
12 machine of the Computing Center (Rekencentrum). He always aroused my
13 interest in other disciplines of science, such as neurophysiology, and
14 taught me to have a much broader view at problems from different
17 {\flushright Cosmin Grigorescu\\ Eindhoven\\
\today\\
}