October 2, 2001

Dispute between federal officials racing to protect nation from possible used by terrorists of weapons of mass destruction and experts who hold more mundane instruments pose more credible threats is throwing light on threat assessment; discipline, more art than science, relies on technical knowledge of what is possible, inferences about terrorists' resources and intelligence data on terrorists' aims and goals; field is rife with uncertainties and challenge of disentangling vulnerability from real danger; diagrams; table of risks of attacks with chemical and biological arms; photos (M)

Psychologist who study how people perceive potential hazards say many precautions Americans are taking in wake of terrorist attacks, while of dubious value in saving lives, can play helpful psychological role; note government's failure to prevent attacks may have heightened public's fears; diagram of how people perceive risks; photo (M)

Florida Official Plans Race Katherine Harris, Florida's secretary of state, who supervised the presidential recount, is expected to announce that she will run for Congress next year. PAGE A16

Officials at colleges in New York City are concerned that city might not seem so appealing to students and their families following Sept 11 terrorist attack; however, colleges report no drop off in inquiries and high school guidance counselors say students are keeping to original plans; photo (M)

Memorial service is held in Central Park for more than 600 employees of bond trading firm Cantor Fitzgerald who were killed in attack on World Trade Center; Pres Bush sends letter of sympathy; Mayor Rudolph W Giuliani, in his remarks at event, notes that no business suffered more than Cantor Fitzgerald and that 1,500 children have lost parent; Howard W Lutnick, chairman of Cantor Fitzgerald, delivers emotional address; Giuliani also attends memorial service at Cathedral Church of St John the Divine for 73 kitchen workers from Windows on the World restaurant and pledges support for children of those who were lost; Sens Charles E Schumer and Hillary Rodham Clinton are also among speakers at memorial for restaurant workers; photo (M)