BEIJING — In China, the names of things are often either ornately poetic or jarringly direct. A new, wildly popular app among young Chinese people is definitively the latter. It's called, simply, “Are You Dead?" In a vast country whose young people are increasingly on the move, the new, one-button app — which has taken the country by digital storm this month — is essentially exactly what it says it is. People who live alone in far-off cities and may be at risk — or just perceived as such by friends or relatives — can push an outsized green circle on their phone screens and send proof of life over the network to a friend or loved one. The cost: 8 yuan (about $1.10). It's simple and straightforward — essentially a 21st-century Chinese digital version of those American pendants with an alert button on them for senior citizens that gave birth to the famed TV commercial: “I've fallen, and I can't get up!” Developed by three young people in their 20s, “Are You Dead?” became the most downloaded paid app on the Apple App Store in China last week, according to local media re