Findings will be published in a report and presented to Congress and the Department of Homeland Security.

"We are in an era when it is easier to attack than defend," said David McIntyre, director of the Integrative Center for Homeland Security at Texas A&M University.

"In the past, it was very hard for a single individual to launch an attack against a city," McIntyre said. "Technology is allowing disaffected people to have an inordinate impact on our lives - terrorists for sure, but also homegrown knuckleheads like Timothy McVeigh or screwballs like the Unabomber."

McIntyre is one of nearly three-dozen people, including representatives of the Department of Homeland Security, NASA, Valero Energy Corp., the Houston Astros and others who are to address the gathering at Rice's Baker Institute.

Frank Michel, a spokesman for Houston Mayor Bill White, who is to give the keynote address, said the gathering should not be construed as a sign the city is especially vulnerable.

"It is better to be talking and planning and refining our preparations for any eventualities," he said. "It doesn't mean people should panic or that we have access to information people should worry about."

The city has a responsibility to be prepared, he said.

Angel Zayas, a former FBI agent who is now director of security and safety for the Astros, said he'll share tips on what has worked best at Minute Maid Park, which has about 43,000 seats.

"They want to get our perspective on what we do," Zayas said. "One of the reasons they chose us is because we run a very safe, secure venue."

Discussion will include how the stadium uses security personnel, cameras and other measures, he said.

"We do a lot to get ready, we do a lot to run a safe stadium," he said. "Just because you don't see us, doesn't mean we aren't doing it. Trust me, they are safe," he said of fans.

William Wilkins, corporate security projects manager for Valero, said most refineries have made great strides in recent years to better detect and deter threats.

"The benefits of attacking a target are always measured against the cost, resources, and likelihood of success in that strike," he said.

Terrorists seeking relevance look for symbolic targets that will result in mass deaths and media attention, Wilkins said.

Wilkins said he works in all regions of the country, and that he's been most impressed with Houston and the surrounding area.

"Houston, in my opinion, is best prepared, and exemplified that in response to the last hurricane we had," he said.