World and Nation

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George W. Bush undergoes heart procedure

Former President George W. Bush underwent a surgical procedure Tuesday morning in which doctors inserted a stent to open a blocked artery, aides said.

Bush, 67, went for an annual physical checkup at the Cooper Clinic in Dallas on Monday, and doctors discovered the blockage. He agreed to have the stent inserted at Texas Health Presbyterian Hospital.

Aides said the procedure was completed without complication and added that Bush was awake and in high spirits. They said he was set to be released from the hospital Wednesday and would resume a normal schedule Thursday.

While his vice president, Dick Cheney, has had repeated heart troubles, culminating in a transplant last year, Bush has been known for his strong health and commitment to physical fitness. He was an avid runner for decades until encountering knee trouble during office. He then switched to bicycling.

Since leaving office, he has led annual 100-kilometer bike rides through the Texas heat with military veterans injured in Afghanistan and Iraq. He participated in his most recent such event in May at his ranch outside Crawford, Texas.

—Peter Baker, The New York Times

Tools pinpoint natural gas leaks, maximizing green qualities

WASHINGTON - Natural gas is hailed as green and safe, but its environmental benefits and ability to temper climate change are reduced by its tendency to leak into the air undetected. Now, laser technology, some of it borrowed from the telecommunications industry, is giving engineers and scientists crucial new tools to measure leaks and track them to their source.

Natural gas escapes into the atmosphere from two basic sources: natural ones, like swamps and marshes, and human activity, like leaking gas wells and pipelines. The boom in natural gas production has raised concerns about a subsequent boom in leaks, although how much gas escapes remains a mystery. The Environmental Protection Agency has been working on the question for years.

But whether from man-made or natural causes, methane is a major contributor to global warming when released in the atmosphere. According to the EPA, over a 100-year period, a pound of methane is 25 times more powerful than carbon dioxide in warming the climate. It can also be dangerous: In 2010, one of Pacific Gas & Electric’s pipelines leaked in San Bruno, Calif., south of San Francisco, and the ensuing explosion killed eight people.

“Leaking methane is becoming increasingly relevant from a greenhouse gas standpoint,” said Joseph T. Hodges, a scientist at the National Institute of Standards and Technology, who helped develop the laser technology used in the new portable detector.

Other companies use different techniques for gas detection. Physical Sciences of Andover, Mass., has an instrument like a lantern that projects a laser beam and measures what bounces back. About 2,000 are in use worldwide, according to Michael B. Frish, a manager there.

“Natural gas is the new green energy, supposedly,” he said, but finding and fixing the leaks would make it greener.

—Matthew L. Wald, The New York Times

Meeting may decide fate of Obama-Pu

WASHINGTON - Secretary of State John Kerry and Defense Secretary Chuck Hagel plan to meet here in Washington with their Russian counterparts Friday for a day of talks that could determine the fate of a September summit meeting between President Barack Obama and the Russian president, Vladimir Putin.

State Department officials on Tuesday afternoon confirmed the meeting with Sergey V. Lavrov, the Russian foreign minister, and Sergei K. Shoigu, the defense minister. Jen Psaki, the State Department spokeswoman, said the four officials would discuss “a number of pressing bilateral and global issues.”

At the top of that list of difficult questions is certain to be the status of next month’s planned meeting between Obama and Putin, which has been in doubt for weeks because of Russia’s refusal to return Edward J. Snowden to the United States to face charges of leaking national security secrets and other issues between the two countries.

Russian officials said they expected the presidential summit to go on as planned. And they waved aside the assertion by the United States that the decision on Snowden should affect whether Obama and Putin come together.

—Michael D. Shear and Steven Lee Myers, The New York Times

Iran’s new president says nuclear talks could succeed

Iran’s new president said Tuesday that he was ready for serious negotiations with the big powers over the disputed Iranian nuclear program, adding that his country does not wish to threaten anyone and dismissing the U.S. and European sanctions levied on Iran as counterproductive.

Iran has insisted that its nuclear program is peaceful but the United States, members of the European Union, Israel and many other countries suspect that Iran wants to achieve the ability to make nuclear weapons.

Rouhani made the assertions in a series of Twitter messages sent via his official English-language account during a news conference in Tehran, his first since taking the oath of office Saturday.

The Obama administration has expressed hope that Rouhani’s election could lay the basis for progress over the nuclear dispute. At the same time, Congress has intensified the sanctions pressure on Iran. Last week, the House of Representatives overwhelmingly approved legislation that could, if enacted and fully enforced, effectively stop Iran’s oil exports. On Monday, 76 senators said President Barack Obama should toughen the sanctions against Iran even as it pursues negotiations.

Referring to the sanctions, Rouhani said in one Twitter post: “We don’t want to see continuation of language of pressure, or carrot and stick, we never liked that idea and still don’t.”

—Rick Gladstone, The New York Times