上海大龙凤论坛

Twenty-one people have died and another six are missing as of Sunday evening after heavy rainfall hit Xi’an, Northwest China’s Shaanxi Province, and caused mountain floods and mudslides on Friday evening.  Due to the impact of short-duration heavy rain, mountain floods and mudslides struck a village in Chang’an district in Xi’an around 6 pm on ... Read more

A team of scientists has built a heat engine out of a single atom. Heat engines, like steam engines or internal combustion engines, convert heat into motion. To create the minuscule engine, physicist Johannes Roßnagel of University of Mainz and colleagues heated and cooled a calcium ion with an electric field and a laser, causing ... Read more

Many preschoolers take a surprisingly long and bumpy mental path to the realization that people can have mistaken beliefs — say, thinking that a ball is in a basket when it has secretly been moved to a toy box. Traditional learning curves, in which kids gradually move from knowing nothing to complete understanding, don’t apply ... Read more

One of the most pressing and perplexing questions parents have to answer is what to do about screen time for little ones. Even scientists and doctors are stumped. That’s because no one knows how digital media such as smartphones, iPads and other screens affect children. The American Academy of Pediatrics recently put out guidelines, but ... Read more

Pluto has no rings — New Horizons triple-checked. An exhaustive search for rings and dust particles around the dwarf planet before, during and after the spacecraft flew past Pluto in 2015 has come up empty. “It’s a very long paper to say we didn’t find anything,” says team member Tod Lauer of the analysis, posted ... Read more