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KNOW IT ALL: Thursday's Top 5 Stories at NBC News

From the punishing cold affecting 100 million Americans to the warnings of a superbug spreading in Los Angeles, see the stories we're following.

Good morning, and happy Lunar New Year. Here are some of the stories we’re following today:

1. Dangerous cold descends, shattering records

Another wave of blistering arctic air is pushing across a third of the country, punishing 100 million Americans in the Midwest, Northeast and all the way down to Florida. Some parts could see cold records shattered. Already in Kentucky, the cities of Paducah and Jackson were at minus-8 degrees and zero degrees, respectively — their coldest for Feb. 19 since records began in 1895. "The frigid air in the U.S. comes courtesy of the Siberian Express," said The Weather Channel's Mike Bettes. "It's traveling 5,000 miles over the North Pole." This arctic onslaught is not over yet, and could hang around through Saturday in some areas. Read more in NEWS.

2. UCLA patients may have been exposed to superbug

Hospital officials are warning patients who underwent endoscopic procedures between October 2014 and January that they may have been exposed to a bacterial "superbug." More than 160 patients of a Los Angeles hospital could be affected, and the bug may have contributed to two deaths, UCLA Health System officials said Wednesday. The "superbug," known as CRE, is "a family of germs" highly resistant to antibiotics. Read more in HEALTH.

3. UMass reverses ban on Iranians in science classes

The University of Massachusetts backpedaled Wednesday after saying it would ban Iranian nationals from its science and engineering programs — a controversial policy change that was announced last week. The school said it consulted with lawyers and the State Department to reverse the decision. "This approach reflects the university's longstanding commitment to wide access to educational opportunities," school officials said in a statement. While some Iranian students told NBC News they are pleased with the change, they still are calling for dialogue with the school. Read more in NEWS.

4. Vanilla Ice calls burglary a ‘misunderstanding’

The "Ice Ice Baby" rapper, born Robert Van Winkle, was arrested Wednesday for allegedly burglarizing a home in South Florida in December. Police in Lantana say furniture, a pool heater, bicycles and other items vanished from the foreclosure property, next to a home that Van Winkle was renovating. He stars in the DIY Network/HGTV show "The Vanilla Ice Project." Read more in NEWS.

5. Whom did Eddie Murphy refuse to play at ‘SNL40?’

The former "Saturday Night Live" cast member made a brief appearance during Sunday's 40th anniversary special on NBC. While Chris Rock gave a tribute to Murphy, who hadn't appeared on the show in 30 years, Murphy was supposed to do more. According to another former cast member, Norm Macdonald, Murphy was asked to do an impression of a certain embattled comedian but rejected the idea. Read more in POP CULTURE.

And now this ...

The rumors about Apple developing a self-driving car probably aren't true, but that doesn't mean you can't crack jokes about it on Twitter.