A closed-door summit on controversial bird flu research starts today, and the newly released guest list reveals that the event will be dominated by virologists.

Rick Santorum released four years' worth of tax returns Wednesday evening which showed that he is wealthy by any measure.

But his returns may also allow his critics, both those aligned with Mitt Romney, his chief rival for the Republican presidential nomination and those who aren't, to attack the former U.S. senator from Pennsylvania for not giving as much to charity as many others at his income level.

The world of international relations seems to have focused on Pakistan today: The president of Iran and the president of Afghanistan both made their way to the country just as tensions between Iran and Israel made the news and just as reports emerged that the U.S. and the Taliban were beginning secret talks.

The official agenda of the meetings is to discuss counter-terrorism and transnational organized crimes at a regional conference tomorrow in Islamabad.

The meteoric rise of New York Knicks point guard Jeremy Lin has echoes of Tim Tebow, the Denver Broncos quarterback who caused such a stir last fall.

Republican Presidential candidate Rick Santorum saw his income rise after he lost a Senate reelection bid in 2007.

According to records released to Politico late yesterday by the Santorum campaign, the former Pennsylvania senator earned $659,000 in 2007; $952,000 in 2008; $1.1 million in 2009 and $923,000 in 2010.

Good morning!

Our early headlines:

-- Thai Police Say Iranian Bomb Suspects Targeted Israeli Diplomats

-- The Economy: Housing Starts Up; Unemployment Claims Decline

After days of accusations from Israel, Thai police confirmed that three Iranians suspected of setting off explosives in Bangkok were targeting Israeli diplomats.

Gen. Prewpan Dhamapong, Thailand's top policeman, said they "know for certain" the explosives were meant for Israeli diplomats.

The AP reports:

"'This issue was about individuals and the targets were specific,' he said. 'This was something personal.'"

Mitt Romney has worn his opposition to the Obama administration's bailout of GM and Chrysler into Michigan as a badge of honor in the lead up to the state's Republican presidential primary at the end of the month.

But that message may be a harder sell for him against the backdrop of GM reporting Thursday that it posted record profits in 2011 of $7.6 billion, 62 percent higher than the previous year's.

To win the 2012 Republican presidential nomination, a candidate must secure 1,144 delegates, a simple majority of those available. But how delegates are chosen differs state by state.

On Thursday's Fresh Air, political scientist Josh Putnam, author of the blog Frontloading HQ, explains how delegates are chosen, why the process varies by state, and how reforms instituted since the 1968 Democratic National Convention have changed the process of delegate selection.

We have a slew of economic data out today and the big picture is that the economy is on the rebound. So, let's get to the numbers:

-- The Labor Department said the number of people seeking jobless benefits dropped by 13,000 to a seasonally adjusted 348,000. The AP reports "it was the fourth drop in five weeks and the fewest number of claims since March 2008."

-- Led by a surge in apartments, housing starts were up 1.5 percent.

-- In January producer prices rose 0.1 percent.