【推荐1】It’s not just in your head: a desire to curl up on the sofa after a day spent toiling at the computer could be a physical response to mentally demanding work, according to a study that links mental exhaustion to changes in brain physiology that cause feelings of tiredness.

The study was conducted by neuroscientist Antonius Wiehler at the Paris Brain Institute and his colleagues. To learn the cause of mental exhaustion, the research team enrolled 40 participants and assigned 24 of them to perform a challenging task. These included looking at a computer screen and matching different letters that appeared. The other 16 participants did a similar, but easier task. Both teams worked for six hours, and had two ten-minute breaks.

While the study participants focused on their work, Wiehler and his team scanned the glutamate (谷氨酸) in the brains of the participants. Glutamate is an important signalling molecule in the brain that works in memory and learning. Too much glutamate may upset the brain’s functions, which means the brain is tired and it must rest.

The researchers found that participants who laboured on the more difficult task had higher levels of glutamate in the brain than those who worked on the easier task. The result suggested people who spend more than six hours working on a task that requires a lot of thought are more likely to feel tired.

And now that a system has been established to measure metabolic (新陈代谢的) changes in response to mental fatigue, the team hope to learn more about how to recover from mental exhaustion. While the researchers haven’t worked out a new solution, Wiehler offers that, “I would employ good old recipes: rest and sleep! There is good evidence that glutamate is eliminated from a period of rest. A good nap can be as short as 20 minutes, but can make us feel totally refreshed.”

【推荐3】Why build a house when you can print one instead?Startups（初创企业）around the world are now using 3 D printing technology for home construction.They say it's faster, cheaper and more sustainable than traditional methods.Printing houses can also save huge amounts of wood（垃圾堆）.

Currently, 3 D printing systems can equal the work output of 10 to 20 workers in five or six different trades, said Jason Ballard, a 3 D printing construction startup, according to AP News.The machines can work 24 hours a day as well

So how do these 3 D printers "print" a house anyway?Machines deposit（使沉积）thin layers of material — such as concrete（混凝土）, metal and plastic — until the three﹣dimensional house is built from the ground up.And a house can be completed within 120 hours, according to CNN.

Ballard said that 3 D printing was like the most powerful automation of all the automations we could discover.This powerful automation has the potential to prevent rising prices in the housing market, homelessness and overcrowding.But the technology behind 3 D printing houses is still in its early stages of development.For example, ICON alone has only printed 24 houses in the US and Mexico.But（梦想家）from dreaming of larger applications of this technology.

"With the 3 D printed home, we're now setting the tone for the future：the rapid realization of affordable homes with control over the shape of your own house, " said Yasin Torunoglu（市议员）for housing in the community of the Netherlands' first 3 D printed house.

【推荐1】When we think of technology, we tend to think of computers, smartphones, and the Internet among other high-tech inventions. But technological development also applies to clocks. The creation of mechanical gears in clocks was a great leap forward for timekeeping devices. Here are just a few of the milestones in their history.

The Pendulum (钟摆) Clock

While clocks using springs and gears had already been invented by the 1500s, it was the pendulum clock developed by Christiaan Huygens in 1657 that gave timepieces a higher level of accuracy. The improvements Huygens made to the pendulum design made it 100 times more accurate than previous clocks. Rather than losing or gaining 15 minutes per day, Huygens' pendulum clocks were accurate within a minute per week.

The Power of Electricity

Clocks that used a battery began to be developed around 1815, but it wasn't until 25 years later that a Scottish clockmaker named Alexander Bain patented a clock powered by an electric current. Bain's clock still used a pendulum, but the pendulum was powered by electromagnetism. More than a hundred years later, in 1957, the first electric watches became available to the public.

Portable Watches

As clock technology advanced and mechanisms became more accurate and thinner, new types of timepieces that could be carried on a person were developed. The earliest of these were pocket watches, which were created in Switzerland in 1574. Centuries later, in 1812, Abraham-Louis Breguet produced the first wristwatch, which he gave to the Queen of Naples, Napoleon's younger sister. Originally, wristwatches were worn by women only and men continued to use pocket watches.

【推荐3】Have you ever forgotten to lock the door of your house? It happens to us all the time.     1     . These smart homes will keep us secure, save us energy, and provide a more comfortable environment to live in.

Intelligent Controls

Today, we have to use switches for our lights and remote controls for our TVs. In the future, we will be using advanced technology every day for automatic control of just about everything in our home. You will no longer have to think about turning switches on and off yourself.     2     All controls will respond to voice commands, so if you want to change your routine, you just say aloud what you want and the home system will obey.

Regular Health Checks

    3    Your bed, for example will record how well you sleep every night. It will also be checking your body weight. Smart toilets will be keeping constant track of your heath as well. They can warm you early on if there is something abnormal or if you have a critical illness such as cancer, and potentially save your life.

No More Disasters

Smart homes will be able to prevent serious damage from accidents. For example, if a water pipe starts leaking, or if there is a shot in the electrical wiring, your smart home will detect it and provide you with the relevant information.     4    

This smart technology is not a fantasy. Many of these new innovations are already available and being used in some homes.     5     Nevertheless, it will take some years before most new homes begin to use this new technology.

【推荐1】At 65, Bryony Harris took out her pension (退休金) and signed up for a psychotherapy (心理治疗) course. “I’m happy that I used my pension to train for a new career,” she says. Now, at 74, she has a successful psychotherapy practice in Fredrikstad, Norway. “I just knew it was the right time, and I felt equipped to do it. It was the very best thing I ever did for myself.”

The four-year course was on the coast of Denmark. To get there, Harris drove for five hours through southern Norway. “It always felt like coming home,” she says. Her experience was transformative (具有转折性的). Practising psychotherapy, she says, “helps me to understand the word ‘calling’.”

And yet Harris has had many careers over the decades. At university in Kingston upon Thames, London, she trained as an architect, and then, worked as one “for short and long periods” while raising four children. Next came a period as a photographer on a community arts project, then teaching photography. “The world offered more possibilities than I had ever realised,” Harris says. She regards these moves as gradual shifts (转换) rather than reinvention. “I have never made a decision such as ‘I’m going to stop doing that and do something else.’ It’s always been a gentle progression.”

Years ago, she and her husband had a dream to open a shop specialising in books about folklore, mythology and tradition. The shop, in Hatherleigh, Devon, is “where the idea of therapy came into my mind. Because in a small independent bookshop, people open up and talk.” Harris also says that her “therapy side was hiding in the background” when she taught photography. In her 40s, she had a short period of counselling (咨询). She no longer recalls exactly why, but it must have had an impact because when she turned 60, she wrote letters “to people who had been hugely influential in my life.” She searched for her former counsellor, but unfortunately couldn’t find him.

Harris has a can-do spirit. The best psychotherapy course was in Denmark, so first she had to learn Danish. “I really love a good challenge. Sometimes you can feel very stuck, but that is how I have lived my life,” she says.

When she was a child, Harris’s parents liked moving. She had nine homes before she went to university. “Now, I have no desire to uproot myself.” Her flat looks out over a river, and she has lived there longer than she has lived anywhere else. Each week brings fresh calls to her practice.

【推荐3】This year's hottest destination is Mars. On 23 July, China launched the Tianwen-1 mission to the Red Planet — one of three spacecrafts' planning to head there in 2020. This is China's second interplanetary mission, but the first that the nation has launched on its own. The other, Phobos-Grunt, was a cooperation with Russia that didn't make it out of Earth's orbit after blasting off in 2011.

The new mission, called Tianwen, translated as "questions to heaven" — consists of an orbiter, a lander and a rover, the last of which will be named via a public competition. "It's very ambitious because it's a four-part mission: there's the launch, getting into orbit, the landing and the rover, and every single step has to go right, says space consultant Laura Forczyk. All those steps must work on the first try, an achievement no other space program me has accomplished on a Mars mission because of the difficulty of landing there.

If all goes well, Tianwen-1 will arrive at Mars in February 2021 and the lander and rover will touch down two or three months later. They will take pictures from the surface, measure the soil composition, make radar observations of the planet's underground structure and observe Mars's magnetic field. Due to the harsh environment on Mars, the rover is expected to last about 90 Martian days. It weighs around 240 kilograms, about the same as China's Yutu-2 rover, which is currently roaming the moon. "The Chinese mission to the far side of the moon has been hugely successful, so they are building on that success now," says Forczyk.

The orbiter, which will relay data from the lander and rover back to scientists on Earth, also carries a suite of scientific instruments. It has two cameras and a spectrometer (光谱仪), which it will use to create a map of the mineral composition of Mars's surface, as well as radar and detectors to examine particles in the Martian atmosphere. It will also look for deposits of water ice that could be helpful for future explorers.

Tianwen-1 won't be alone in Mars orbit. The United Arab Emirates has just launched its first mission to Mars, and NASA's Perseverance rover is set to launch on 30 July. These missions are all leaving now because Mars is at its closest point to Earth, which happens once every two years.