World and Nation

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Director of counterterrorism center is resigning

WASHINGTON — Michael E. Leiter, head of the nation’s main counterterrorism center, is resigning after nearly four years in a job that has increasingly focused on detecting and thwarting smaller and more diverse terrorist plots.

Leiter, 42, one of the few senior national security officials from the Bush administration that President Barack Obama kept on, will leave July 8, roughly when the White House is expected to release an updated counterterrorism strategy that Leiter contributed to, administration officials said.

Friends and colleagues said Leiter’s departure was expected, as his tenure coincided with one of the most demanding periods after the Sept. 11 attacks. Even as al-Qaida’s leadership in Pakistan came under increasing pressure, culminating in the death of Osama bin Laden on May 2, al-Qaida affiliates blossomed in Yemen and North Africa, and U.S. officials warned of a threat from homegrown terrorists here.

In a telephone interview Thursday, Leiter, who is newly remarried, said he was stepping down both for personal reasons and to allow his successor to “bring fresh eyes to the problems we face.” He has not yet decided on his next job, he said.

—Eric Schmitt, The New York Times

IBM researchers create high-speed graphene circuits

IBM researchers said Thursday that they had designed high-speed circuits from graphene, an ultra-thin material that has promising applications, from high-bandwidth communication to a new generation of low-cost smartphone and television displays.

The IBM advance, which the researchers reported in the journal Science, is a circuit known as a broadband frequency mixer that was built on a wafer of silicon. Widely used in all kinds of communications products, the circuits shift signals from one frequency to another.

In the Science paper, the IBM researchers describe a demonstration in which they deposited several layers of graphene on a silicon wafer, then created circuits based on graphene transistors and components known as inductors. They demonstrated frequency mixing up to speeds of 10 gigahertz. In the past IBM has created stand-alone graphene transistors, but not complete electronic circuits.

—John Markoff, The New York Times

Stretches of the country face record-setting heat

It was so hot in St. Paul, Minn., that a once-giant snow pile, the remnant of a long, harsh and suddenly vanquished winter, succumbed this week in 103-degree heat. And it was so miserable in Philadelphia that a meteorologist summed up the forecast in three words: “Considerably more disgusting” than the day before.

A heat wave that has taken hold across much of the Central and Eastern United States intensified Thursday, with cities from St. Louis to Richmond, Va., seeing record or near-record high temperatures, cloying humidity and dangerously elevated ozone levels. “We are seeing conditions that we normally don’t have until August,” said Jim Keeney, a meteorologist with the National Weather Service. “The heat has been pushed north all the way into Wisconsin, and in the North especially, we are seeing temperatures 15 to 20 degrees above normal.”

A sampling of high temperatures from the past several days in places where early June temperatures are often in the low 80s: Washington, 99 on Thursday; Indianapolis, 92 on Wednesday; St. Louis, 97 on Monday; Richmond, 99 on Thursday; Minneapolis, 102 on Tuesday; Cincinnati, 96 on Thursday; Detroit, 95 on Wednesday; Kansas City, Mo., 96 on Monday; Philadelphia, 99 on Thursday but felt like 103; Baltimore, 103 on Thursday; Milwaukee, 97 on Tuesday; and New York, 96, on Thursday.

—Timothy Williams, The New York Times