【推荐1】Snow leopards (豹) are so hard to photograph that scientists aren’t even sure how many of these endangered animals still live in the wild.

The Snow Leopard Conservancy(SLC) set up 20 cameras in Russia in 2010 to learn more about the big cats. After a full six months, they had exactly zero picture! That’s when the organization understood they needed help. And the only people who could help them in finding the leopards were the very people from whom they wanted to protect the animals—local hunters (猎人).

Hunting snow leopards is against the law in Russia, but in the terrible climate of Siberia, the few people living there had to turn to poaching (盗猎) to feed their families.

In 2013, Russian naturalist Sergei Spitsyn approached Mergen Markov, a local hunter, and told him his project. Markov agreed to set up the camera where he knew he would find leopards, and it worked.

Markov, once a poacher, works full time for the conservationists now and has 10 cameras monitoring leopards. “I visit each camera once a month. I have known this whole region since I was a child,” he said proudly.

The World Wildlife Fund (WWF) began working with other local villagers in 2015. The village would be paid 40,000 rubles at the end of the year if the image of a snow leopard is caught. WWF also rents horses from the villagers so that they do not need to make money by poaching anymore. “Today there are far fewer leopard poachers but leopards still get caught in traps set for other animals, so I have to stay watchful,” said Markov.

Changing guns for cameras has made a big difference in the lives of these former poachers, the village, and the Russian snow leopards. The number of snow leopards has been rising and their population is expected to recover to normal levels within 10 years.

【推荐2】To grow sugary dates（海枣） in the sand, Siwa’s farmers must first make the desert suitable for farming. An oasis（绿洲）in Egypt, Siwa has been home to humans for thousands of years. Since ancient times, the oasis has hosted farms producing some of the most valuable dates in Egypt, and the sugary dates have appeared on Egyptians' tables.

The desert environment in Siwa is not quite fit for plants to grow. For example, the water there contains much salt. However, it is with local people's effort that date trees, crops and other plants grow in harmony despite the complex agricultural fields, which impressed me a lot during my visit to the oasis. To make a new piece of field, farmers first remove the top soil and replace it with a mixture of sand and waste matter from animals. The first plants are medicinal plants. Then, farmers plant date trees and olive trees. These farming skills are passed down from generation to generation.

To grow date trees is demanding. And it takes 10 years for a new date tree to mature, but once it does, the tree produces generous fruit: around 110 pounds of dates per year. Each farmer picks dates with the skilled hands. They climb the trees using nothing more than a belt. In total, Siwa grows more than 25,000 tons of dates from 280,000 trees per year.

The dates can be eaten fresh, or made dry. Every part of the date tree is significant in Siwa, from leaves made into beds and boxes to wood used to build houses. And then, of course, there's the fruit itself. The dates can be cooked with goat meat or mixed with eggs for breakfast. They can also be mixed with flour, water, and olive oil, and boiled slowly to make a local dessert.

【推荐3】It is like a scene from a horror film：a spider web is several meters wide，which is home to thousands of spiders.And that was what Jason G．Goldman，an animal behavior researcher，found along a muddy path in the Peruvian Amazon jungle—the web arched from tree to tree，a structure containing too many spiders to count.They appeared to function as a society，just like ants or bees.

Anelosimus eximius，the species Goldman met in the rainforest，is not the only kind of social spiders in the world，but it does construct the biggest webs.Some can reach more than 7.6m long and 1.5m wide.A web of that size could contain as many as 50,000 individual spiders.

Anelosimus eximius was first discovered more than a century ago by a French scientist named Eugene Simon.More social spiders have been discovered since.One was found as recently as 2006.

An Anelosimus eximius colony(群体) contains adult males and females as well as youngsters，but the majority of spiders on the web are females. Males account for only between 5% and 22% of any colony’s population.Social spiders work together to build，maintain and clean their webs.They work together to catch prey(猎物)，and dine together when they trap a large feast.The females work together to care for the young in the colony.They feed their youngsters by vomiting(吐出) up food for them，just like mother birds.

Why did these spiders become social？Researchers have discovered three ecological(生态的) elements that often lead to cooperative(合作的) living among spiders.

Social spiders tend to feed on bigger prey，for one thing.Spiders living in places where it is difficult to hunt large or more profitable prey alone may eventually figure out that it is in their interest to work together.

A．	B．
C．	D．

【推荐2】Taking good care of your teeth may be linked to better brain health, according to a study published in the July 5, 2023, online issue of Neurology. “Our study found that gum (牙龈) disease and tooth loss were linked to brain shrinkage (萎缩) in the hippocampus, which plays a role in memory and Alzheimer’s disease,” said study author Satoshi Yamaguchi, Ph.D., DDS (牙医外科博士) , of Tohoku University in Sendai, Japan.

The study involved 172 people with an average age of 67 without memory problems. Participants had dental exams and took memory tests at the beginning of the study. They also had brain scans to measure the volume of the hippocampus at the beginning of the study and again four years later. For each participant, researchers counted the number of teeth and checked the amount of gum disease.

Researchers found that the number of teeth and amount of gum disease was linked to changes in the left hippocampus of the brain. For people with mild gum disease, having fewer teeth was associated with a faster rate of brain shrinkage, which is the same for people with severe gum disease having more teeth. After adjusting for age, researchers found that for people with mild gum disease, the increase in the rate of brain shrinkage due to one less tooth was equal to nearly one year of brain aging. Conversely, for people with severe gum disease, the increase in brain shrinkage due to one more tooth was equal to 1.3 years of brain aging.

“These results highlight the importance of preserving the health of the teeth and not just maintaining the teeth,” Yamaguchi said. “The findings suggest that controlling the progression of gum disease through regular dental visits is crucial, and that teeth with severe gum disease may need to be removed and replaced with appropriate prosthetic ones.”

Yamaguchi said future studies are needed with larger groups of people. Another limitation of the study is that it was conducted in one region of Japan, so the results may not be generalizable to other locations.

【推荐1】NASA has a new job listing, and it's no joke. The US space agency is looking for a "joker" to join their planned mission to Mars.

A mission to Mars is no laughing matter. On average, the red planet is 140 million. miles (225 million kilometers) away from Earth. A trip there would take around eight months in a small spacecraft. And Mars has a communications delay of 20 minutes. This means that astronauts will have to wait 20 minutes for a reply, when an emergency happens.

"When you're living with others in a confined space for a long period of time, such as on a mission to Mars, problems are likely to occur," Jeffrey Johnson, a scientist at the University of Florida, told The Guardian.

This is probably why NASA wants an astronaut with a sense of humor. "These are. people that have the ability to pull everyone together," Johnson said.

In stressful situations, perhaps humor is a way to know we aren't alone. By laughing together, we share our stress. Then we can focus on our jobs instead of just worrying.

There are other examples of team "clowns". One example is the journey to the South Pole led by Norwegian explorer Roald Amundsen. It was a difficult journey. full of danger. Adolf Lindstrom, a cook at Amundsen's team, was a "clown". He made people laugh through the whole journey. Amundsen later wrote that Lindstrom was the most valuable member of the team.

But if you're hoping that your favorite TV comedian will fly to Mars, that probably won't happen.

"Being funny won't be enough to land somebody the job," Johnson said. "They also need to be an excellent engineer."

Besides, they must be in top physical condition.

【推荐3】A study has shown that severe stress lasting weeks or months can damage cell communications in the brain’s memory areas. Recently, researchers from University of California, Irvine, have provided the first evidence that short-term stress lasting for a few hours has the same effect.

“Stress does exist in our lives and cannot be avoided,” said Dr. Baram, leader of the UC Irvine School. “Our findings can play an important role in the present development of medicine that might prevent these undesirable effects and offer understanding of why some people are forgetful or have difficulty keeping the memories.”

In their study, Baram and her UC Irvine colleagues identified a novel process in which stress caused these effects. They found that, severe stress activated(激活) Corticotropin Releasing Hormones(CRH), which prevented the brain from keeping memory.

Memory takes place at synapses, where there are connections through which brain cells communicate. These synapses lie on dendritic spines(神经元). In rat and mouse studies, Baram’s group saw that the release(释放) of CRH in the brain’s primary memory center led to the rapid breakup of these dendritic spines, which in turn limited the ability of synapses to collect and store memories.

In addition, the researchers reproduced the effects of stress on dendritic spines by keeping low levels of CRH, and watching how the spines ruptured over minutes. “Fortunately, once we removed the CRH, the spines seemed to grow back again, ” Baram said. “And this study can play a role in the creation of treatments to address stress-related memory loss.”

【推荐1】NASA is studying ways to build human habitations on the Red Planet. In 2016, SpaceX publicly announced a plan to begin building settlements Mars. This mission (任务)could put people on Mars by 2026. This is why astrobiology students at Villanova began their Mars Gardens project, investigating which plants and vegetables can grow in iron oxide-rich Martian soil simulant (模拟物).

A few billion years ago, Mars had a better environment, complete with oceans, a mild climate and quite possibly —life. It has since lost most of its atmosphere and water and there's currently no water on its surface. Water (or ice) is present beneath the surface, however, as well as in the planet's icy polar areas. The tough conditions on Mars make it necessary for all plants to be grown in heated, pressurized greenhouses with significant compensations (补充)made for atmosphere, wetness and water.

In their greenhouse experiments, the Villanova students took measures to create an environment that's both plant-friendly and similar to what would be found in greenhouses on Mars. They made sure, for example that plants received roughly the same amount of sunlight as they would on Mars. The students found that their success rates improve by using multiwavelength LEDs and adding potting soil or earthworm feces.

The students were able to get certain vegetables from consideration. For example, the low light on Mars does not lend itself well to growing plants that require full sun, which include favorites like tomatoes, beans, corn or many root plants. Carrots also don't make the cut. Potatoes largely don't thrive in the simulant soil and low light conditions, but sweet potatoes do a little better.

The students found that dandelions (蒲公英)would grow well on Mars and have significant benefits: they grow quickly, every part of the plant is eatable, and they have high nutritional value. Other thriving plants include microgreens, lettuce, peas and so on.

【推荐2】Three Boys and a Dad

Brad closed the door slowly as Sue left home to visit her mother. Expecting a whole day to relax, he was thinking whether to read the newspaper or watch his favourite TV talk show on his first day off in months. “This will be like a walk in the park.” he’d told his wife. “I’ll look after the kids, and you can go visit your mom.”

Things started well, but just after eight o'clock, his three little “good kids”---Mike, Randy, and Alex --- came down the stairs in their night clothes and shouted “breakfast, daddy.” When food had not appeared on within thirty seconds, Randy began using his spoon on Alex’s head as if it were a drum. Alex started to shout loudly in time to the beat(节拍) . Mike chanted “Where’s my toast, where’s my toast” in the background. Brad realized his newspaper would have to wait for a few seconds.

Life became worse after breakfast. Mike wore Randy’s underwear on his head. Randy locked himself in the bathroom, while Alex shouted again because he was going to wet his pants. Nobody could find clean socks, although they were before their eyes. Someone named “Not me” had spilled a whole glass of orange juice into the basket of clean clothes. Brad knew the talk show had already started.

By ten o'clock, things were out of control. Alex was wondering why the fish in the fish bowl refused his bread and butter. Mike was trying to show off his talent by decorating kitchen wall with his color pencils. Randy, thankfully, appeared to be reading quietly in the sitting room, but closer examination showed that he was eating apple jam straight from the bottle with his hands. Brad realized that the talk show was over and reading would be impossible.

At exactly 11:17, Brad called the daycare center(日托所).“I suddenly have to go into work and my wife is away. Can I bring the boys over in a few minutes?” The answer was obviously “yes” because Brad was smiling.

【推荐3】Young sunflowers turn and swing every day. New findings add to evidence that the plants are animal-like.

Harmer, a professor in the University of California at Davis’ Department of Plant Biology, carried out a series of experiments on sunflowers in the field, in pots outdoors and in indoor growth chambers.

By staking plants so that they could not move, Harmer showed that he could destroy their ability to track the sun. He also noticed that sunflowers prevented from moving were not as tough and leafy as those that were free to move. When plants were moved indoor with a settled overhead light, they continued to swing back and forth for a few days.

The indoor plants did start tracking the “sun” again when the apparent source of lighting was moved across the room. The plants could reliably track the movement and return at night when the artificial day was close to a 24-hour cycle, but not when it was closer to 30 hours.

When sunflowers track the sun, the cast sides of their stems grew more rapidly than the west sides. Ai night, the west sides grew faster as the stem swung the other way. The team identified a number of genes that were expressed at higher levels on the sunward side of the plant during the day, or on the other side at night. A plant growth-regulating hormone, called auxin, appears to be a key driver.

The “dance” to the sun cycle obviously slows when the sunflower matures and its flowers open up. At that point, the plants stop moving during the day and settle down facing the sun in the east.

“Bees like warm flowers.” Harmer said, adding that the bees are cold-blooded, so landing on a warm flower saves them energy and perhaps feels really good.

“The morning warmth changes the flowers in a way to make them more appealing to insects, perhaps causing them to release more attractive scents earlier in the day.” he said. “We’re currently testing this idea.”