Mr. Turner himself has periodically sought a merger or an alliance with a media company that would give him more power than he has under the current structure.

Huizenga, who has periodically sought Marino's advice on the Dolphins, seemed to be taken aback by Marino's announcement.

The tower gives a commanding view of the campus and the city of Austin, and student groups have periodically sought to have the observation deck reopened.

Among them will be the dialogue with Washington that Iran has periodically sought, a lifting of many long-standing economic sanctions, and even light water reactors for nuclear power with Russia and the West controlling access to the fuel.

A United States attorney for the Southern District in the 1980's, Mr. Giuliani said he had periodically sought to add a legal practice to supplement and round out his ventures since he started Giuliani Partners in 2002.

Throughout her career Ms. Chung, 59, has periodically sought to show that she has a sense of humor about herself and her work.

Gene Russianoff, a staff attorney with the New York Public Interest Research Group, said the board has periodically sought money from civic groups for the call center and other projects.

Although state and Federal prosecutors have periodically sought to eliminate criminal elements from the commercial garbage-hauling trade, the Giuliani effort is the first by City Hall to rein in an industry of more than 600 companies that collect trash from 250,000 businesses and private institutions.

Loveland has periodically sought to expand its borders by annexing surrounding areas, primarily to the more commercially active west.

Nominations are sought and considered periodically from a variety of sources, including from members of the Board and Advisory Council, Society Members, staff, and experts in the space community.