My research research interests are in areas of linear algebra, matrix analysis and combinatorics. The heart of my research is the nonnegative inverse eigenvalue problem (NIEP), a problem that seen as one of the most difficult and intriguing open problems in matrix theory today. Starting with the NIEP my research interests broadened to several aspects of matrix theory with special emphasis on the problems that are in different ways connected with positivity. Particular challenge in my research are problems that impose spectral and structural properties on a matrix simultaneously. While the main emphasis of my research is not on real world applications, my work is closely connected with applications in several areas that range from finance to science and engineering. My work on the questions about the sign patterns of coefficients of polynomials and power series brought my research interest outside the scope of matrix theory. My research brings methods from matrix theory to study eventual behaviour of coefficients of power series, which is a novel approach to questions of this type.