城市人造光源的规模有多大
2025-06-19 16:32 by 夏日永别
卫星照片下的城市夜晚以灯火通明著称，然而卫星照片难以区分城市人造灯的类别，是路灯、还是信号和装饰灯？德国研究人员开发了名叫 Nachtlichter 的应用，在公民科学家的帮助下对 22 平方公里区域内 234,044 个光源进行了统计和分类。结果显示，用于广告和审美用途的人造光源总数超过了照明用的路灯。研究人员估计，整个德国的午夜时分仍然会有 7800 万左右的光源仍然亮着，显示减少人造光污染有着巨大的潜力。
www.nature.com/articles/s44284-025-00239-5
#科学
BY Solidot
From the Files app, scroll down to Internal storage, and tap on WhatsApp. Once you’re there, go to Media and then WhatsApp Stickers. Don’t be surprised if you find a large number of files in that folder—it holds your personal collection of stickers and every one you’ve ever received. Even the bad ones.Tap the three dots in the top right corner of your screen to Select all. If you want to trim the fat and grab only the best of the best, this is the perfect time to do so: choose the ones you want to export by long-pressing one file to activate selection mode, and then tapping on the rest. Once you’re done, hit the Share button (that “less than”-like symbol at the top of your screen). If you have a big collection—more than 500 stickers, for example—it’s possible that nothing will happen when you tap the Share button. Be patient—your phone’s just struggling with a heavy load.On the menu that pops from the bottom of the screen, choose Telegram, and then select the chat named Saved messages. This is a chat only you can see, and it will serve as your sticker bank. Unlike WhatsApp, Telegram doesn’t store your favorite stickers in a quick-access reservoir right beside the typing field, but you’ll be able to snatch them out of your Saved messages chat and forward them to any of your Telegram contacts. This also means you won’t have a quick way to save incoming stickers like you did on WhatsApp, so you’ll have to forward them from one chat to the other.
Like a stock, you can buy and hold Bitcoin as an investment. You can even now do so in special retirement accounts called Bitcoin IRAs. No matter where you choose to hold your Bitcoin, people’s philosophies on how to invest it vary: Some buy and hold long term, some buy and aim to sell after a price rally, and others bet on its price decreasing. Bitcoin’s price over time has experienced big price swings, going as low as $5,165 and as high as $28,990 in 2020 alone. “I think in some places, people might be using Bitcoin to pay for things, but the truth is that it’s an asset that looks like it’s going to be increasing in value relatively quickly for some time,” Marquez says. “So why would you sell something that’s going to be worth so much more next year than it is today? The majority of people that hold it are long-term investors.”
Solidot from us