PERISCOPE

But transit systems have large numbers of access points that, unlike airports, make it difficult to screen people who go in and out. Two senior U.S. counter-terrorism officials, who declined to be named because of security sensitivities, also say existing technology is not overly effective at screening crowds for hidden hazards. Officials fear that investing large amounts of taxpayer cash in unproven gadgets might be a poor use of resources. The most important safeguard against transit attacks, say officials, is increased passenger vigilance. But Homeland Security officials say they are working to address the worries of riders. "From low tech to high tech, there are steps that can and are being taken to increase security for transit passengers," said Mark Hatfield Jr., a spokesman for the Transportation Security Administration.

--Mark Hosenball

Wealth: Mideast Moolah

Call it the blessing of oil. In a recent study Merrill Lynch and Capgemini report that the number of Middle Eastern households worth more than $1 million has grown by 9.5 percent since last year. The authors also cut their forecasts for the growth rate in total wealth held by households in Asia, North America and Europe but tripled their forecast for the Middle East. They now expect Middle Eastern family-held fortunes to rise by 9.1 percent over the next four years, to a total of $1.5 trillion.

The main reason for the wealth boom is simple, the authors say: rising oil prices. But unlike the 1980s and 1990s, when oil shocks (and windfalls) were temporary, says Capgemini's Louise Brakenhielm, this one could have legs, due to rising demand, limited production capacity and highly volatile markets. (The International Energy Agency also predicts a new era of more expensive oil). All told, says Brakenhielm, the new realities of oil should pump at least an additional half-trillion dollars into the hands of Middle Eastern elites by the end of the decade.

--John Sparks