【推荐2】To persist, life must reproduce (繁衍). Scientists at the University of Vermont, Tufts University, and the Wyss Institute for Biologically Inspired Engineering at Harvard University have discovered an entirely new form of biological reproduction and applied their discovery to create the first-ever, self-replicating (自我复制的) living robots.

Named Xenobots after the African clawed frog from which scientists take their stem cells, the machines are less than 0.04 inches wide —small enough to travel inside human bodies. They can walk and swim, survive for weeks without food, and work together in groups. They even have regenerative capabilities; when the scientists sliced into one robot, it healed by itself and kept moving.

The Xenobots could potentially be used toward a host of tasks. Xenobots could be used to clean up radioactive waste and collect microplastics in the oceans. Some Xepobots had holes in their center, which could potentially be used to transport drugs or medicines. “Traditional robots degrade (降解) over time and can produce harmful ecological and health side effects,” researchers said in the study, which was published in the Proceedings of the National Academy of Sciences. As biological machines, Xenobots are more environmentally friendly and safer for human health. Aside from these immediate practical tasks, Xenobots could also help researchers to learn more about cell biology—opening the doors to future advancement in human health and longevity.

While the prospect of self-replicating biotechnology could spark concern, the researchers said that the living machines were entirely contained in a lab and easily destroyed, as they are biodegradable and regulated by experts. “There are many things that are possible if we take advantage of this kind of plasticity (可塑性) and ability of cells to solve problems,” said Joshua Bongard, one of the lead researchers at the University of Vermont.

【推荐3】If you live in a town or city on the edge of a desert or coastline where sand dunes form, you might understand the threat they can have. It’s, sometimes, a piece of cake for them to cover roads, buildings, farms and other man-made developments with their unpredictable movements. Thus, figuring out how they move is important for preventing some natural disasters.

Now scientists have discovered that dunes have been secretly moving in ways we never knew before. There are different explanations on dune interaction, however, Karol Bacik, first author on the new dune study, and his colleagues have found a new one for dune movement. The researchers employed high-speed cameras to observe how dunes separated by distance can act as if they’re connected.

It turns out, currents flowing over sand dunes can carry “information” to other dunes downstream in the form of swirls(旋涡). For instance, as wind or water flows over the top of a dune, it slightly moves. This can generate “swirls” on the back of a downstream dune and push it in a direction opposite the movement of the front dune.

It’s the first time that researchers were able to provide causal explanations for some of these strange, previously unpredictable movements. The team also hopes to get out of the laboratory and into the real world, to see if their models can be applied to dune movements in complex natural systems. They plan to use satellite images over large deserts to track groups of dunes over long periods.

Perhaps they can start to alter the dune marching orders in the near future. Imagine being able to tell a dune field exactly how you want it to move. That’s the idea that this research might one day make possible.

【推荐2】A bargain is something offered at a low and advantageous price. A more recent definition is: a bargain is a dirty trick to force money out of the pockets of silly and innocent people.

The cost of producing a new—for example—toothpaste would make 80 p the proper price for it, so we will market it at £ 1.20. It is not a bad toothpaste, and as people like to try new things it will sell well to start with; but the attraction of novelty soon fades, so sales will fall. When that happens we will reduce the price to £ l. 15. And we will turn it into a bargain by printing 5 p OFF all over it.

Sometimes it is not 5 p OFF but l p OFF. What breathtaking rudeness to advertise l p OFF your soap or washing powder or whatever! Even the poorest old-age pensioner ought to regard this as an insult(侮辱), but he doesn’t. A bargain must not be missed. People say one has to have washing powder(or whatever)and one might as well buy it a penny cheaper.

The real danger starts when unnecessary things become “bargains”. Many people just cannot resist bargains. Provided they think they are getting a bargain they will buy clothes they will never wear or furniture they have no space for. Once I heard of a man who bought an electric saw as a bargain and cut off two of his fingers the next day. But he had no regrets: the saw had been truly cheap.

Quite a few people actually believe that they make money on such bargains. A lady once told me: “I’ve had a lucky day today. I bought a dress for £120, reduced from £400; and I bought a beautiful Persian carpet for £600, reduced from £900.” It will never occur to her that she has actually wasted £720. She feels as though she had made £ 580. She also feels, I am sure, that if she had more time for shopping, she could make a living out of it.

Some people buy in large quantities because it is cheaper. Once a couple bought enough sugar for their lifetime and the lifetime of their children and grandchildren. They thought it a bargain not to be missed. When the sugar arrived they didn’t know where to store it —until they realized that their toilet was a very spacious one. So that was where they piled up their sugar. Not only did their guests feel rather strange whenever they were offered sugar to put into their coffee, but the toilet became extremely sticky.

To offer bargains is a commercial trick to make the poor poorer. When greedy fools fall for this trick, it serves them right.

【推荐3】Despite earning more than $100,000 in household income, many people feel that they are living month to month and that a loss of employment or sudden medical emergency could easily move them from the upper middle class to low income earners. This feeling of being on the “edge” of poverty, despite these levels of income, seems a bit ridiculous but it really comes down to easy credit, misunderstanding of their incomes and peer (同辈) group pressures.

Even in today’s tough economy, for those with six-figure incomes credit is easy to come by. Credit companies may have cut back offerings to those in lower income brackets(等级) due to the recent credit reforms, but there seems to be little or no effect on high income earners. Their being able to get credit without difficulty gives them a false sense of security that makes them spend way more than their incomes can afford. That’s why they accumulate credit card debt faster than average.

Many higher income earners feel like they are making lots of money now, and believe that they will continue to make big money. This may reduce their feeling that they need to watch their money carefully now. Hand in hand with that, many of them probably believe that they are making more money than they really are—or said another way, the money they make will go farther than it really does.

Meanwhile, many young professionals who are earning good incomes don’t come from particularly privileged backgrounds, and their reference point may be that they are making twice (or more) than their parents were—so they spend like that us well. They don’t take account of the effect of inflation(通货膨胀), which means that the cost of living is much higher than that in their parents’ generation. Further, the more you earn, the more you pay in tax. Rather than focusing on after-tax incomes, many high income earners only look at the top figures. A $100,000 income before tax is only about $70,000 after tax.