1 . It’s common knowledge that the woman in Leonardo da Vinci’s most famous painting seems to look back at viewers, following them with her eyes no matter where they are in the room. But this common knowledge turns out wrong.

A new study finds that the woman in the painting is actually looking out at an angle of 15.4° off to the viewer’s right — well outside the range that people normally believe when they think someone is looking right at them. In other words, said the study author, Horstmann, “She’s not looking at you.”

This is ironic (讽刺), because the entire phenomenon of a person’s gaze (凝视) in a photograph or painting seeming to follow the viewer is called the “Mona Lisa effect”, which is absolutely real. If a person is illustrated or photographed looking straight ahead, even people viewing the portrait from an angle will feel they are being looked at. As long as the angle of the person’s gaze is no more than about 5 degrees off to either side, the Mona Lisa effect occurs.

Horstmann and his co-author were studying this effect for its application in the creation of artificial-intelligence avatars (虚拟头像) when Horstmann took a long look at the “Mona Lisa” and realized she wasn’t looking at him.

To make sure it wasn’t just him, the researchers gathered 24 people to view images of the “Mona Lisa” on a computer screen. They set a ruler between the viewer and the screen and asked the participants to note which number on the ruler intersected (相交) Mona Lisa’s gaze. To calculate the angle of Mona Lisa’s gaze as she looked at the viewer, they moved the ruler farther from or closer to the screen during the study. Consistently, the researchers found, participants judged that the woman in the “Mona Lisa” portrait was not looking straight at them, but slightly off to their right.

So why do people repeat the belief that her eyes seem to follow the viewer? Horstmann isn’t sure. It’s possible, he said, that people have the desire to be looked at, so they think the woman is looking straight at them. Or maybe the people who first coined the term “Mona Lisa effect” just thought it was a cool name.

4 . Plants: we eat them, juice them-and now it seems we can mine them too!

After a successful experiment on the island of Borneo, the botany professor Alan Baker and a group of researchers want to introduce phytomining (harvesting minerals from plants) as a better, partial substitute for traditional mining.

Phytomining, also known as agromining, means collecting metals from live plants. However, this can only be done with a group of plants known as "hyperaccumulators". There are around 700 identified types worldwide, and what makes these hyperaccumulators special is that they naturally attract and absorb minerals through their roots-metals poisonous to other plants-and then store huge, pure concentrations of these minerals in their bodies. The metals can then be extracted from the plants' sap(汁;液), oil, or sometimes even live tissue.

Baker and his colleagues see a lot of potential in phytomining. Not only can it help meet the growing global demand for metals, but is a way of undoing some of that damage to the environment by traditional mining.

One of the biggest problems with traditional mining is that it pollutes the surrounding area. Phytomining can extract metal waste, plus planting the hyperaccumulators would regrow the deforested areas caused by mining operations. Aside from this, if phytomining is able to replace part of traditional mining, then there would be fewer instances of bad mining practices like abandoned mines, which pollute the nearby waters. Also, since phytomining provides metals that are already naturally pure, there is no need to use huge amounts of energy to purify the ore(矿石).

Phytomining has its drawbacks. Harvesting plants on a large scale is expensive today, compared to traditional mining. Besides, plants can be wiped out by diseases or unexpected weather conditions.

However, there are many reasons to consider phytomining. After all, we need to make sure that our planet can keep up and sustainable practices like phytomining give us the hope that our advancement doesn't mean sacrificing Mother Earth.

5 . Tricia Hurt, her husband Brian, and their son Brady were out enjoying a fishing adventure on Marsh-Miller Lake in Wisconsin when they found a baby bear in huge suffering. According to the locals in the area, the little bear had been running on land with a plastic tub on his head for three to four days, but he somehow got into the water, worsening his condition.

The bear could be seen swimming in fear and shifting away from the family as they edged the boat closer. He was terrified, but the tub was quickly filled with water and he was in danger of drowning.

"Go a little faster, Brady. Get in front of him," Tricia instructed her son to drive the boat closer to the animal. Brian got close to the bear and tried to pull the tub out, but it had become too slippery. Brian lost his control, but he wasn't discouraged because the bear's ears had managed to come loose. That meant the plastic tub wasn't stuck and he just had to get closer.

The rescue lasted about five minutes and they made several attempts before the tub finally came off. Brady made the boat circle around the bear and his father gave one last try that set the animal free. Once the tub came off, the bear was able to swim easily to the shore and catch a much-needed break.

The family was extremely relieved as Tricia called out to the swimming animal, "Swim happily.''

"We were so excited! We did our good deed for the day. It felt good to help the poor bear. You don't like to see animals struggle." Tricia later said in an interview.

When the Hurts returned to their resort, everyone offered their gratitude. Tracy, a native, said, "No one else had been able to help the bear for several days as it struggled with the deadly tub on its head. We need more people like the Hurts!"

6 . It’s almost spring, the time of year when the change in seasons could lead to some pretty fascinating cloud activity in the sky. NASA and the GLOBE Program are inviting you to take part in a citizen science cloud observation challenge.

The GLOBE Program is an international science and education program providing the public with the opportunity to participate in the scientific process. From March 15 through April 15, citizen scientists can make up to 10 cloud observations per day using the GLOBE Observer app or one of the other data entry options (for trained GLOBE members). Challenge participants with the most observations will be congratulated by a NASA scientist in a video posted on the GLOBE Program’s website and social media.

“The GLOBE Program is offering this challenge to show how important it is to NASA to have citizen scientist observations from ground up,” said Marile Colon Robles, lead for the GLOBE Clouds team at NASA’s Langley Research Center in Hampton, Virginia.

Researchers use and value this citizen science cloud data because it helps confirm data from Earth-observing instruments.

Scientists at Langley work with a set of six instruments known as the Clouds and the Earth’s Radiant Energy System (CERES). Even though CERES’ instruments use advanced technology, it is not always easy for researchers to positively identify all types of clouds in their images.

For example, it can be difficult to tell thin, wispy cirrus clouds (细小的卷云) from snow, since both are cold and bright; it is even more so when cirrus clouds are above a surface with patchy snow (片状雪) or snow cover. One solution is to look at satellite images from a particular area and compare them to data submitted by citizen scientists on the ground.

“Looking at what an observer recorded as clouds and looking at their surface observations really helps us better understand the images that were matched from the satellite,” said Colon Robles.

You don’t have to be a cloud-gazing professional to participate. For those who want to be part of the challenge but don’t have a lot of experience identifying clouds, Colon Robles offers the following advice: “Just go outside. The more clouds you observe, the more comfortable you’ll be collecting data.”

7 . Choosing the right hiking equipment will make your walk safer and more comfortable. Getting it right is easy with our pick of the best. Don’t hesitate to grab them!

SMART SOCKS

Smartwool Women’s PhD Outdoor Light Print Crew Walking Socks (£16.09)

Built for mile after mile of trail, these socks are so light and seamless that you’ll barely notice you’re wearing them.

Darn Tough Kelso Micro Crew Light Cushion (£20)

Keep you cool while going the distance in these wool socks. They’re cushioned and silky soft.

1000 Mile Fusion Walking Sock (£15.99, twin pack)

Need extra comfort? The Fusion Walking Sock has a blister-free guarantee thanks to clever double-layer technology and padded zones.

LIGHTWEIGHT JACKETS

Smartwool Merino Smart Ultra Light Hoodie (£114.99)

This windproof layer packs away into its pocket.

Berghaus Women’s Skerray Smock (£70)

Stay warm if the wind gets up in this super-light, water-repellent smock jacket with a fitting hood. It packs away into the small pocket.

Finisterre Mistral Waterproof Jacket (£185)

Light yet fully waterproof, this cool high-quality jacket has zipped pockets and an adjustable foldaway hood.

SUMMER SHORTS

Jack Wolfskin Overland Zip Away (£115)

Always chilly when you set out but boiling by the time you’re climbing that hill? With these clever pants, you get a pair of soft-shell trousers and a pair of shorts in one.

9 . What do you want to be when you grow up? My answer has always been a vet.

We didn’t have pets growing up because my mother was scared of animals. She passed on some of this fear to me. It’s not common you find someone who’s scared of animals but wants to be a vet. Still, I knew this is what I wanted.

Vet school was nothing like I had imagined. Within the first few weeks, any fears I had about being a vet vanished (消失). In the fourth year, we were introduced to surgery. I loved it. Stitching (缝) wounds was like a satisfying game of Tetris (俄罗斯方块), where all the pieces fit beautifully together to make something broken whole again. It solidified my belief that this was the right fit for me.

These were the most challenging and rewarding two years of my life, and before I knew it, they were over. I was officially a veterinary surgeon (兽医). Surprisingly, I felt empty after I finished. Why wasn’t I excited to move on? I had completely forgotten to think about what comes next. I panicked! I felt as if I had spent the last decade of my life writing exams and working crazy hours only to come out on the other side, completely clueless.

There were so many options to choose from. I could start a clinic, work at another practice or even pursue further studies. It was my father who suggested I travel to gain some perspective. I hesitantly decided to spend some time in New Zealand with my aunt who also happens to be a vet.

New Zealand was beautiful! I finally had a chance to think about what I wanted. One of the vets there allowed me to observe their practice. Working with vet nurses really stood out for me. We don’t have vet nurses in India! It is a blessing (幸事) to have such experienced and dedicated individuals as a part of your support system. After a whole year of what felt like aimless wandering (徘徊), this experience helped me decide I wanted to work overseas.

So, to all the other confused vets out there who haven’t figured things out: It’s completely okay to feel confused and lost! Most people feel the same way at some point in their careers. Don’t be afraid to try new things even if you feel difficult or impossible.

10 . Should we allow modern buildings to be built next to older buildings in a historic area of a city? In order to answer this question, we must first examine whether people really want to preserve the historic feel of an area.Not all historical buildings are attractive.However, there may be other reasons—for example, economic reasons—why they should be preserved.So, let us assume(假设) that historical buildings are both attractive and important to the majority of people.What should we do then if a new building is needed?

In my view, new architectural styles can exist perfectly well alongside an older style.Indeed, there are many examples in my own hometown of Tours where modern designs have been placed very successfully next to old buildings.As long as the building in question is pleasing and does not dominate(影响) its surroundings too much, it often improves the attractiveness of the area.

It is true that there are examples of new buildings which have spoilt(破坏) the area they are in, but the same can be said of some old buildings too.Yet people still speak against new buildings in historic areas.I think this is simply because people are naturally conservative(保守的) and do not like change.

Although we have to respect people’s feelings as fellow users of the buildings, I believe that it is the duty of the architect and planner to move things forward. If we always reproduced what was there before, we would all still be living in caves .Thus, I would argue against copying previous architectural styles and choose something fresh and different, even though that might be the more risky choice.