Hong Kong police arrested prominent opposition figures and warned other protesters could share their fate this weekend, raising tensions as authorities seek to quell pro-democracy demonstrations that have raged for almost three months. —Josh Petri

Here are today’s top stories

Public health officials warned Americans who aren’t already smokers to avoid e-cigarettes and other vaping devices after a mysterious outbreak of a severe lung disease.

Sausages, ketchup, mustard and plastic plates are all essential ingredients for Americans tending to their grills this Labor Day weekend. Soon they’ll be 15% more expensive to import from China.

Apple just revealed the date for its latest iPhone event. Google's elite hacking team just revealed a bug in the current iPhone's software. 

Recycling battery packs is key to the future of EVs, and China is emerging as a leader in the field. 

President Donald Trump had a busy day on Twitter, criticizing GM for shrinking its U.S. manufacturing presence and denying that the U.S. played a role in the explosion of an Iranian missile.

Hurricane Dorian may be the first of multiple powerful hurricanes this year. The last two decades have seen some of the most powerful and destructive hurricane seasons on record, a function of coastal development, warmer water, wetter air, higher seas and storms just being storms.

What’s Luke Kawa thinking? The Pure Alpha fund of Bridgewater’s legendary Ray Dalio has seen better days—it's down about 6% year-to-date. The proximate cause of his woes, according to Bloomberg’s reporting: bearish bets on global interest rates gone awry.

What you’ll need to know tomorrow

• Elizabeth Warren once wrote a book on how to get rich.
• Twitter CEO Jack Dorsey's account was hacked.
• Sushi prices show where the cost of living in the U.S. is on the rise.
• Miami is worried about a new hurricane hazard: Dockless scooters.
• Dubai halts work on its mega airport as Gulf economies stumble.
• Popeye's keeps running out of chicken.
• Rhum agricole is the spirit you're about to see everywhere.

What you’ll want to read tonight in Businessweek

The Race to Build the World's Most Precise Clock

So far, the potential applications for a clock with 15 decimal places of precision are theoretical and aspirational. But that’s not stopping labs around the world from competing, using different elements, to reach the same goal.

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