State security organs appear to be keeping close tabs on the inflows of guests. Activist Wang Youcai, a leader in the 1989 student protests, was reportedly arrested by the police. He disappeared last Monday after travelling here to join as an invited alumnus. ``It has been confirmed by the Government that Wang Youcai was arrested by the Beijing Public Security Bureau when he disappeared onApril 27,'' the Information Centre of Human Rights and Democratic Movement in China reported. Dissident sources suspect authorities detained him to prevent him from attempting to influence the tone of the occasion.

Eighteen other university alumni, now dissidents in the United States, took advantage of the centenary to issue an open letter urging all those attending celebrations to press for the release of former students who are now political prisoners. Signatories included Wang Dan, astrophysicist Fang Lizhi and Wang Juntao all leading figures in the 1989 Tiananmen Square movement. But Government leaders and the state media are highlighting different facets of the university's history, such as its role as the hotbed of Marxist discussion that gave rise to the Communist Party. A Beijing-based alumnus said the party ``will dictate what image the world will see for the anniversary. But the Tiananmen movement will not be far from the minds of anyone there, even the most patriotic alumni,'' he said.Peopleassociated with the University are the country's intellectual elite, he said. ``They know the school's history, and it would be unrealistic to expect their views about what the anniversary means to fit the Government's,'' he added.