1. During the period April 26 to July 25, 1995, I was at the Abdus Salam Interna-
tional Centre for Theoretical Physics, Trieste, Italy on a Visiting Fellowship
at the Mathematics Section.
2. During the period June 19-21, 1995, I visited Prof. Dr. Mimmo Iannelli at
Dipartimento di Matematica, Universita di Trento, Italy. I gave a talk about age-
structured epidemic models.
3. During the period October 25-29, 1999, I visited Prof. Dr. K. Dietz at the
Institute of Medical Biometry, University of Tubingen, Germany, and I discussed
with him possibilities for a project in age-structured epidemic models.
4. In the period January 19 to February 3, 2000, I was at the Center for Ad-
vanced Mathematical Sciences, (CAMS), American University of Beirut,
Lebanon, as an associate.

5. During the period October 20, 2000 to January 18, 2001, I was at the Abdus Salam
International Centre for Theoretical Physics, Trieste, Italy, on a Visiting
Fellowship at the Mathematics Section.
6. During the period November 26-30, 2000, I visited Prof. Dr. Mimmo Iannelli
at Dipartimento di Matematica, Universita di Trento, Italy. I gave a talk about
age-structured epidemic models.
7. During the period June 11 to August 11, 2001, I visited the Mathematical and Theoretical Biology Institute, MTBI, Cornell University. My duties included conducting research with MTBI faculty and observing their summer institute.
8. In the period May 5 to July 17, 2004, I visited the Institute of mathematics
of the University of Potsdam, Potsdam, Germany, and I worked in research
problems of age-structured epidemic models. Also, I started a joint work with
Prof. Dr. N. Tarkhanv of the Institute of Mathematics at Potsdam University,
Germany.
9. In February 21, 2005, I have been appointed as visiting associate at the Institute
of Pure & Applied Mathematics (IMPA), Rio de Janeiro, Brazil.

10. For a year (2005-2006), I visited the Center for Advanced Mathematical Sciences (CAMS), American University of Beirut, Beirut, Lebanon, as an Arab Regional Fellow, I was supported by a grant from the Arab Fund for Economic and Social Development.