Bloomberg Drivers in San Francisco, Manhattan and Tel Aviv may soon have another safety tool at their disposal: a mobile app that alerts them to dangers ahead in the road. Nexar Ltd., an Israeli startup whose app records video from a smartphone’s camera to capture hard brakes and collisions, will turn its users into a vehicle-to-vehicle network to prevent …

  Washington / AFP Twitter has begun rolling out a new weapon in the fight against harassment by “trolls” whose often anonymous vitriol can make the messaging service an unwelcoming place. The move comes as online social networks struggle to balance free speech with intimidation and aggression that make many fearful of speaking freely. “The amount of abuse, bullying, and …

  Wetzlar / DPA David Bowie had one, so does Scarlett Johannson, while Lenny Kravitz produced a book with one: a Leica camera. There’s no arguing that the Leica is the German camera everyone covets. Back in the days when German cameras led the world, a Leica was the ultimate. But then the firm in Wetzlar, eastern Germany began slipping, …