A rainy day can be a chance to recharge. While you relaxed on the sofa with a movie, the raindrops falling on your windows might one day provide the power for your TV. This is the idea behind an invention that harvests energy from water.

The technology is based on the triboelectric (摩擦电的)effect. An engineer at the University of Hawaii, David Ma knew that it’s possible to generate electricity by rubbing two things together. So, he thought, “Why don’t we use water?”

A drop of water sliding across a surface coated with two different materials would generate enough friction to create an electrical charge. By placing metal wires that the drop of water touched as it moved, it should be possible to harvest electricity, he reasoned.

It worked. In fact, the researchers lit up 15 LED bulbs with a single moving water drop.

This is not the first time that scientists have got electricity from water-generated friction( 摩 擦 ). Earlier experiments, though, harvested the charge produced in a surface by a sliding drop of water. There, the surface had acted as an electrode(电极). This is different. The energy of friction is being harvested from the water itself.

“It turns out,” Ma says, “the charge in the water drop is way more than the charge produced in the other electrode.” In fact, his team’s model generated almost 100 times more power than previous experiments from a single drop of water.

“The technology could someday power phones, sensors or other small electronics,” says Christopher Oshman, an engineer at the Colorado School of Mines. “This work is a step toward harvesting the energy of moving objects all around us, including ourselves, to power the electronic appliances we use every day,” he says.

Ma has shown that the technology can work in a lab, Oshman says. Next, the Colorado researcher would like to see it tried on a larger scale, such as on an umbrella.

Fact or Fiction?

Non-fiction can be broken down into many categories. One category is literary non-fiction, which is still based in fact but employs some of the storytelling elements that fiction uses. Literary non-fiction includes a type of autobiography(自传) called memoir. Memoir most often focuses on a certain period of the author’s life. It is, by definition, rooted in truth. Still, people sometimes question whether memoir should be categorized as non-fiction at all.

As non-fiction, memoir is intended to be factual. Is this really the case, though, considering memoir relies on human memory? One classic study, led by psychologist   Elizabeth   Loftus, showed how easily an interviewer’s choice of wording can influence an eyewitness’s account of a traffic accident. It is therefore reasonable to wonder whether memoir should continue to be branded as non-fiction.

Certainly,   human   memory can   be   unreliable.   However,   a   memoir   author   is undoubtedly writing about significant and impactful life events. Memories of such events are actually more reliable than others. Studies show that the more influential an event is, the more accurately people recall the details. As an emotionally charged event unfolds, the brain activity changes in a way that amplifies small details. This activity helps build a more precise and accurate memory.

Of course the brain is not a camera that can “save” any memory with perfect accuracy. But if memoir is questionable due to the imperfections of the human mind, then critics will have to tackle non-fiction more broadly. All writers are using their memories when they create, and moreover, they are relying on the memories of others. Journalists conduct interviews to tell a news story and history writers depend on the accuracy of accounts from long ago. Yet they all rightfully fall under the umbrella of non-fiction.

Some people may doubt memoir not because they mistrust human memory, but because they mistrust the author’s morality. Critics may suspect an author of making up events. However, there is no reason to be suspicious of memoir author’s intentions. Writing a factual memoir that appeals to readers has the potential to be profitable for the author, and there is no motivation for a memoir writer to knowingly change or beautify the truth.

Looking beyond the author’s own life events, memoir can inform readers about the world in the same way that other non-fiction can. Memoir has a way of relaying facts about anything from an occupation to brief fashion trends, all of it meaningful to the author.

Every language and culture has curse words (脏话). What gives a curse word its power is partly its meaning and partly its sound. “In English, for example, curse words tend to contain a high percentage of plosive sounds—including P, T and K,” said Ryan McKay, a psychologist at University of London.

Dr. McKay teamed up with his colleague Shiri Lev-Ari to learn whether this familiar pattern went beyond English. They wondered whether it might even represent what’s called sound symbolism. Sound symbolism is when a word sounds like what it means.

The researchers first asked fluent speakers of Hebrew, Hindi, Hungarian, Korean and Russian to list the most vulgar (粗俗的) words they could think of. Once they’d made a list of each language’s most frequently used curse words, the researchers compared these with neutral words from the same language. In these languages, they didn’t find the plosive sounds that seem common in English curse words. “Instead, we found that the vulgar words were defined by what they lacked: the approximant sounds that include letters I, L, R, W and Y, ”Dr. Lev-Ari said.

Next, the scientists invited 215 native speakers of six languages: Arabic, Chinese, Finnish, French, German and Spanish. The participants listened to pairs of words in a language they didn’t speak, and guessed which word in each pair was offensive. In reality, all the words were invented. For example, the researchers started with the Albanian word “zog, ” for “bird, ”and created the pair of fake words “yog" and “tsog. ”Participants were more likely to guess that words without approximants, such as “tsog, ” were curses.

Finally, the researchers combed through the dictionary for English curse words and their cleaned-up versions. Once again, the clean versions included more of the sounds I, L, R, W and Y.

A 20th-century linguistic (语言学的)principle claimed that the sounds of words were arbitrary: Any word could have any meaning. With curse words, though, as in other cases of sound symbolism, “the sounds themselves seem to carry meaning, ”said Lev-Ari. “That’s a new thing, ”said linguist Benjamin Bergen. “Curse words across languages, unrelated to each other, may pattern similarly. ”He also pointed out, to make sure the pattern of approximants missing from curses isn’t an accident, it would be nice to find it in an even larger sample of languages.