【推荐1】Scientists say they have found detailed evidence of ancient rivers on Mars. The discovery supported existing evidence that Mars once had water. The researchers said their findings suggested rivers may have flowed on the surface of Mars for hundreds of thousands of years.

These images were captured by a camera on NASA’s Mars Reconnaissance Orbiter. The camera is able to take detailed pictures of the surface while orbiting the planet from about 400 kilometers away. A team of scientists studied the images, which showed a valley network on Mars.

The team was led by Francesco Salese, a geologist at Utrecht University in the Netherlands. Salese said the scientists studied sedimentary (沉淀物) rocks from a 200 meters high rocky cliff. Sedimentary rocks form when sedimented (使沉积) and transported by water or wind.

“These are sedimentary rocks and were formed by rivers that were likely active for over 100,000 years,” Salese said, adding even without the ability to examine the cliff area on Mars, the pictures show strong similarities to sedimentary rocks found on the earth.

William McMahon is another geologist who was part of the investigation team. He said sedimentary rocks have long been studied on the earth to learn what conditions were like on our planet millions or even billions of years ago. Another leader of the team was Joel Davis, a researcher with Britain’s Natural History Museum. He said scientists had never before been able to examine such a rock formation with such great detail. They created 3D images of the area to get a more detailed understanding of it, which suggested some ancient Martian rivers were several meters deep.

【推荐2】Plenty of kids like to play video games. But is gaming good or bad for their brains? Scientists from the University of Vermont recently found that video games could offer some benefits to the mind. Their study found that gamers did better than non-gamers on two mental tasks.

Bader Chaarania neuroscientist (神经学家), who helped lead the new research, said that scientists have looked at kids who play video games in the past. But many of their studies did not have good sample (样本) sizes. So, Chaarani and his team worked with data, or information, from 2,217 children. All of these children participated in a much larger study. Chaarani’s team just used the information from that study.

The scientists looked at two groups of kids in the study. One group was the non gamer group while the other was the gamer group. All of the kids had their brains scanned with an fMRI scanner at age 9 or 10.The kids did two tasks while in the fMRI scanner The first task was to press a right or left arrow on a computer when they were given instructions, which tested their ability to quickly act. The second task was to remember facial expressions in pictures on the screen. The scientists recorded the time they used, which tested what’s known as working memory.

The results matched the brain scans. For the kids they looked at, areas of the brain involved in working memory, attention and problem solving were more active in gamers Areas of the brain involved in hand-eye coordination (协调) were less active in gamers than non-gamers. Chaarani said that’s likely from practice. It’s like using a muscle. Gamers’ brains seem to have become stronger in this area. So they didn’t need to work as hard to respond to the images viewed on the screen.

Fran Blumberg who studies children’s attention and problem —solving skills agreed with the result of the study but he also advised Chaarani to collect more data as the kids get older. Then he can see whether their skills — and brains — change over time.

【推荐1】The prickly pear cactus (仙人掌) is such a powerful symbol in Mexico that it occupies a prime spot on Mexico’s national flag. The plant was considered sacred(神圣的) by the ancient Aztecs, and modern-day Mexicans eat it, drink it, and even use it in medicines and shampoos. Now scientists have come up with a new use for the bright green plant: producing renewable energy.

Known locally as nopal, the prickly pear is farmed on a massive scale in Mexico. Over the years, only the edible(可食用的) soft inner flesh has been used. The cactus’s thick outer layer (i.e., husk), with all those spines(刺), had always been viewed as a waste product until researchers developed a biogas generator to turn the husks into electricity.

The pilot project(试点项目) devoted to developing the cactus biogas generator began in the south of Mexico City. The area produces 200,000 tons a year of prickly pear cactus—up to 10 tons of which ends up as waste on the floor of the cactus market each day. Then, a local green energy startup company got the idea to turn that waste into energy. The generator is now in place at the cactus market, where the vendors(商贩们) are enthusiastic about this new way to make use of the tons of cactus husks that once went directly into the trash.

The prickly pear has a number of advantages over other biofuel crops, such as wheat, sugarcane(甘蔗), and soybeans(大豆). For one thing, only the husk of the cactus is used for generating biofuel, while its inner flesh is still preserved for food. Therefore, using the plant as a fuel source will not put pressure on food prices.

Moreover, the cactus requires minimum water, and thus is not grown on traditional agricultural lands. This means that no increased competition arises for the water or land presently used for food production.

The project in Mexico City has brought new hope to reducing the use of fossil fuels. If it can be expanded, the prickly pear could be the key to Mexico’s energy future.

【推荐2】Be a Better Gardener

There are always lots of things to learn as a gardener, and many of them can only be learned through getting your hands dirty. But there are some things gardeners can learn from reading or watching.     1    .

What plant families are

Actually, plants have formal scientific Latin names. These names help to categorize (分类) plants, and make it clearer to identify and study those plants. Specific plants are specific varieties of particular species. Species are members of a certain genus (属). And each genus belongs to a broader plant family.

    2    . For example, plants in the Lamiaceae family (mint family) include garden herbs such as lavender, mint and rosemary. In the family, members will generally have aromatic (芳香的) leaves, among other shared characteristics.

    3    

Learning plant families can be a great step forward for those who want to identify more plants around them. Even when we cannot identify plants down to species and variety, knowing which family they belong to can often give us a lot of the information we need. This will often help us to understand the broad characteristics of the plant we are looking at, and where it might be placed in our gardens, or which neighbors it will like.

How to learn plant families

    4    . But I find that a good way to begin is by researching the plants we already have in our garden. Find out which family the different plants belong to, and then take a good and long look at those plants to see their characteristics.     5    .

【推荐3】Few fruits carry more health-promoting antioxidants (抗氧化剂) than blackcurrants (黑加仑). Widely grown in cooler parts of Europe, they are in high demand from consumers seeking chemical-free juices made from the berries. Farmers, though, can struggle to increase productions without relying on chemicals. That could change, not just for blackcurrants but other fruit too, with the careful use of probiotics (益生菌).

Probiotics is mostly known for its use of tiny living things, including certain bacteria, to restore or improve the digestion in people and animals. But plants can benefit from bacteria too. Among other things, bacteria help plants produce things that keep disease-causing viruses off their leaves, support them in collecting nutrition from the environment and help them melt minerals found in the soil.

Knowing all this, Virgilija Gaveliene and Sigita Jurkoniene, of the Institute of Botany Nature Research Centre in Lithuania, set out 10 find a way to use probiotics to increase the production of blackcurrant bushes, which are grown in that country. The researchers also knew from other work that the production of strawberries and raspberries could be increased by exposing plants to a carefully selected mix of bacteria.

As they report in Agricultural Science and Technology, the results were impressive. While thousand blackcurrants collected randomly weighed just over 538 grams, the same number from the field exposed to bacteria treatments weighed nearly 783 grams. A similar increase was also true for the field using the probiotics.

Drs. Jurkoniene and Gaveliene are convinced that the right mix of bacteria can help blackcurrant farmers meet demand without using chemicals. And it could help other growers. What works for berries should, in theory, work for other fruit, like apples, pears and oranges. More experiments are needed to be sure.