1.   Authorities tightened security at federal buildings throughout the city, including the Capitol and the White House.

2.   After its shutdown of television transmission facilities Monday, Serbian authorities further tightened control of the media Thursday by expelling reporters.

3.   But since Abdel Rahman was sentenced, the American authorities have tightened security at most airports in the United States as a protective measure against possible revenge attacks.

4.   Chilean stocks fell to their lowest level in a month after authorities tightened restrictions on foreign investment in financial instruments, including shares.

5.   Chilean stocks fell to their lowest level in a month after authorities tightened restrictions on foreign investment, some of which may have been filtering down to shares.

6.   Concerned that ETA, the Basque separatist group, may try an attack, Spanish authorities have tightened border restrictions and are searching cars entering the city.

7.   Facing the possibility of violent protests when the World Economic Forum begins in New York City on Thursday, authorities have tightened security from the Canadian border to Manhattan.

8.   Fearing terrorists might try to smuggle liquid bombs aboard U.S. airliners, the federal transportation authorities are tightening security measures for trans-Pacific flights.

9.   The authorities have gradually tightened the screws on the group, and it is not clear if its work can continue.

10.   The Egyptian authorities also tightened regulations on nongovernmental organizations last year with a law that was recently declared unconstitutional on technical grounds.