Roger Federer made the most of his rare opportunities Friday against the fastest serve in tennis, cashing in with some classic returns in a 7-6 (6), 7-5, 6-3 win over Ivo Karlovic to reach the fourth round of the Australian Open.

The four-time Australian Open champion fended off Karlovic's set point in the tiebreaker with a return that brought the 6-foot-10 Croatian to the net, then lobbed just over him.

Mexico enacted tough new rules Thursday to ban advertising of "miracle cures" for weight loss, sagging body parts and more serious illnesses like prostate ailments, chronic fatigue and even cancer.

Mexico has a long history of faith healers and home remedies, but the problem has come to a head in the last few years with a constant stream of ads on television for more "scientific" sounding creams that supposedly lift or enlarge breast and buttocks, magnets that help users lose weight, or pills and powders that cure gastric problems or diabetes.

Good news: Sex is safe for most heart patients. If you're healthy enough to walk up two flights of stairs without chest pain or gasping for breath, you can have a love life.

That advice from a leading doctors' group on Thursday addresses one of the most pressing, least discussed issues facing survivors of heart attacks and other heart patients.

A new government study suggests a lot of teenage girls are clueless about their chances of getting pregnant.

In a survey of thousands of teenage mothers who had unintended pregnancies, about a third who didn't use birth control said the reason was they didn't believe they could pregnant.

Twitter has acquired Summify, a Vancouver-based social news aggregator.

"We're extremely excited to announce that Summify has been acquired by Twitter!" Summify announced on its website on Thursday.

The director of Interpol says there is no specific intelligence the Olympics will be targeted.

Ron Noble, secretary-general of the international police agency based in France, also said Thursday that Britain does a good job of screening identification documents against the Interpol database as part of its security procedures.

An international group seeking to preserve the legacy of Winston Churchill is announcing plans Thursday to create the first U.S. research center devoted to the longtime British leader.

The new National Churchill Library and Center will be established between 2013 and 2015 at George Washington University in Washington, D.C., with an $8 million (€6.23 million) pledge from the Chicago-based Churchill Centre.

It's high noon for the humble leap second.

After ten years of talks, governments are headed for a showdown vote this week on an issue that pits technological precision against nature's whims.

Russia will look into the possibility that a U.S. radar station could have inadvertently interfered with the failed Mars moon probe that plummeted to Earth, Russian media reported Tuesday, but experts argued that any such claims were far-fetched.

NASA spokesman Bob Jacobs also said the U.S. space agency was not using the military radar equipment in question at the time of the Russian equipment failure, but instead was using radar in the Mojave desert in the western United States and in Puerto Rico.

If a day without Wikipedia was a bother, think bigger. In this plugged-in world, we would barely be able to cope if the entire Internet went down in a city, state or country for a day or a week.

Sure, we'd survive. People have done it. Countries have, as Egypt did last year during the anti-government protests. And most of civilization went along until the 1990s without the Internet. But now we're so intertwined socially, financially and industrially that suddenly going back to the 1980s would hit the world as hard as a natural disaster, experts say.