The rate of Israeli doctoral and post-doctoral students working and studying abroad - who are several thousands in number at any given time - who do not return home is increasing, according to the Israel Academy of Sciences and Humanities, which conducted a survey through its Web site to find out why. Family, culture, education of their children and finding a suitable professional environment for their work are the main "pull factors" that could bring them home, but political and security considerations, salary and living conditions are among those that prevent them from returning, showed the poll, which was placed on the Web site last February. Prof. Menachem Ya'ari, president of the academy, said he was pleased that 911 doctoral and post-doctoral students abroad responded to the survey and his personal message. Ya'ari said Sunday that the "brain drain" of Israeli academics who did not plan to come back after their studies was growing. Ya'ari said it was impressive that nearly 1,000 of them decided to answer the survey in detail, as it indicated that many of them are nevertheless interesting in returning to Israel if they could find suitable jobs and conditions for research. The academy has initiated a center to remain in contact with doctoral and post-doc students abroad to encourage them to come back, Ya'ari said. The ages of those who responded ranged from 21 to 47, with only 4.9 percent over the age of 45. Two-thirds of them were men, and almost all have Israeli citizenship (a few have Israeli spouses). Almost three-quarters are married and 72% have children, while 86% of them live with Israeli partners. Three-quarters live in the US, 10% in Britain and the rest in other countries around the world. Six in 10 have doctorates, while the rest are studying for their PhDs. Almost three-quarters of those who already have PhDs obtained them in Israel. Fully half of those with doctorates specialize in physics, chemistry and biology. Ninety-five percent have no concrete plans to start an academic career in Israel, but half are actively looking into that possibility. A fifth of those who are thinking of returning home said there was only a small chance to find a suitable job in Israel.