The robots are alive, and now they can reproduce.

Thafs not a continuation to "The Terminator". It's the latest result of research among scientists at Harvard and the University of Vermont. These xenobots, named for the African frog Xenopus laevis, could move around and display collective behavior.

The researchers took stem cells (干细胞)from the skin of frog and put them in salt water, where they came together into balls with a covering of cilia, which are similar to small hairs and enable the organisms (生物体) to move. The scientists noticed that these organisms, xenobots, would collect any particles (粒子) placed in the dish to make piles. They started to wonder whether the tiny robots would do the same thing with individual stem cells, so they conducted a test.

Knowing that xenobots shapes affect their behavior, the researchers tried to figure out which form would help the organism to reproduce repeatedly. They discovered that a "C" shape seemed to be the best. The C-shaped xenobots gathered individual stem cells into groups, which became xenobots of their own. This type of reproduction is based on the organisms movement, rather than growing and then forming a new being as other animals and plants do.

Xenobots are on an unusual line between living organisms and robots. They are organisms because they are made of stem cells and can reproduce. But they are also robots because they can move on their own and perform physical labor. Although most robots are made of metal, robots are given the definition not by their material, but by what they can do.

Before now, Kriegman, a postdoctoral fellow at Harvard University, said, "no one has been using living materials as self-moving, self-powered robots." The researchers hope that the xenobots can help them better understand the process of reproduction 一 a fundamental quality of life — and how to control it. Faced with a world full of self-reproducing problems, such as

Covid-19, Kriegman said studying xenobots could lead scientists closer to solutions.

In recent years, labels have increasingly been used by the food industry. Whether "non-GMO（转基因）"or"zero trans fat","no added hormones" or"sugar-free", consumers are demanding more information about what's in their food.

A report by Nielsen found that 39 percent of consumers would switch from the brands they currently buy to others that provide clearer, more accurate product information. Food manufacturers are using the new labels to meet consumers' demand, with an eye towards giving their products a leg up over the competition, and their bottom lines a boost as well.

On its face, the new marketing strategy makes sense. But these so-called "absence claims" labels are harmful both to the consumers who purchase the products and the industry that supplies them. For example, Hunt's put a "non-GMO" label on its tomatoes a few years ago — despite the fact that, at the time, there was no such thing as a GMO tomato on the market. Over the long term, this strategy will have the opposite effect: by creating fear, we run the risk of damaging consumers' trust.

Eventually, it becomes a question in consumers' minds: Should I have ever been eating these foods in the first place? By purchasing and consuming these types of products, have I already done some kind of harm to me?

For food manufacturers, it will damage consumers' trust, which in turn would lower sales for the whole food industry. And this isn't just supposition. A recent study by a group of academics at the University of Delaware found that "absence claims" labels can stigmatize(污名化)food produced with conventional processes even when there is no scientific evidence that they cause harm.

In addition to the likely negative long-term impact on sales, it sends a message that innovations in farming and food processing are unwelcome, eventually leading to less efficiency, fewer choices for consumers, and, ultimately, more costly food products. Therefore, it's clear that food manufacturers must be careful when using "absence claims" as a marketing strategy. If we allow this kind of label fear-mongering to continue, the losers will be all of us.

Amblyopia is the most common cause of vision loss in children. In all cases of amblyopia, there's a stronger eye and a weaker eye, and it's winner-take-all in the cortex (大脑皮层). The cortex learns to ignore the signal from the weaker eye. By ignoring the weaker eye, the brain doesn't fuse (融合) images from both eyes. As a result, people with amblyopia can have trouble seeing in 3D.

In an attempt to solve this problem, doctors start treating patients with amblyopia at a young age, while their brain pathways are still developing. The children, usually under 7 years old, are often told to wear an eye patch over their strong eye to force the brain to rely on the weaker. But whenever the eye pa tch is removed, the competition can start over. For lasting improvement, new treatments need to teach the brain to stop suppressing(抑制) key visual cues coming from the weaker eye, says neuroscientist Dennis Levi of the University of California.

Now, several research teams are taking a new way that aims to get the brain to make better use of the information coming from both eyes. Several companies are working on treatment s based on this new angle. One is called Luminopia.

Luminopia's therapy involves having children watch videos through a virtual reality headset. As the children watch, the headset blocks out certain parts of the display for each eye, so the patients actually have to combine input from the two images to get the full video.

The company conducted a trial showing that children with amblyopia begin to see better on eye chart assessments after three months of one-hour sessions done six days a week. But they have yet to measure improvements in long-term effectiveness. It is believed that if people with amblyopia don't learn to fuse signals from both eyes from a young age, they never will. So some scientists think attempting to treat adults, whose brains have suppressed signals from their weak eye for decades, is a lost cause.