1 . Painting is an ancient medium and even with the introduction of photography, film and digital technology, it still has remained a persistent mode of expression. So many paintings have come into being over the years but only a small percentage of them could be described as “timeless classics”. The following are some of the most famous paintings of all time.

Painted between 1503 and 1519,Leonardo da Vinci’s attractive portrait has been a subject of controversy since the day it was made, due to two questions: Who’s the subject and why is she smiling? A number of theories for the former have been provided over the years: That she’s the wife of the Florentine merchant Francesco di Bartolomeo del Giocondo and that she’s Leonardo’s mother, Caterina. As for that famous smile, its quality has driven people crazy for hundreds of years.

Whistler’s Mother, or Arrangement in Grey and Black No.1,as it’s actually titled, speaks to the artist’s ambition to pursue art for art’s sake. James Abbott McNeill Whistler painted the work in his London studio in 1871. Whistler’s mother Anna is pictured as one of several elements locked into an arrangement of right angles. Her severe expression fits in with the rigidity of the composition, and it’s somewhat ironic to note that despite Whistler’s formalist intentions, the painting became a symbol of motherhood.

As one of the most significant works produced during the Northern Renaissance, this composition is believed to be one of the first paintings finished in oils. It portrays an Italian merchant and a woman who may or may not be his bride. In 1934.the celebrated art historian Erwin Panofsky proposed that the painting is actually a wedding contract. What can be reliably said is that the piece used orthogonal perspective to create a sense of space. It feels like a painting you could step into.

2 . Spending a day glued to your smartphone probably isn’t doing you any favors. Too much phone use has been linked with a range of concerns, including sleep issues, joint pain and even relationship problems. But if it’s radiation you’re worried about, experts say you don’t have to ditch your phone.

“There’s no risk of anything hazardous or dangerous with radiation from cellphones,” said Gayle Woloschak, an associate dean and professor of radiology at the Northwesterm Univerity Feinberg School of Medicine. As with all cellphones, along with Wi-Fi networks, radio stations, remote controls and GPS, smartphones do send out radiation, said Emily Caffrey, an assistant professor of health physics at the University of Alabama at Birningham. They use invisible energy waves to transmit voices, texts, photos and emails to nearby cell towers, which can carry them to almost anywhere in the world. But nearly three decades of scientific research has not linked such exposures to medical issues like cancer, health authorities including the Food and Drug Administration say. Here’s what we know.

“Radiation” describes many types of energy, some of which do carry risks, explained Dr. Howard Fine, director of the Brain Tumor Center at New York — Presbyterian Weill Cornell Medical Center in New York City, “It is often sent out from radioactive substances”, Atomic bombs, or, to a far lesser degree, X-ray machines, send out energy called ionizing radiation that in high enough or frequent enough amount can damage DNA and cause cancer, Dr. Fine said.

But smartphone energy falls into a category called non-ionizing radiation, Dr. Caffrey said, which isn’t powerful enough to cause this damage. “A lot of people think radiation is radiation, but it’s not all the same,” Dr. Woloschak said. “There’s no DNA damage seen from cellphone use.”

Most experts and health authorities like the F.D.A. and World Health Organization agree that there’s no evidence that smartphone radiation causes health problems. Still, several studies over the years have made headlines for suggesting their links to brain diseases. Many of these studies have since been proved to be false, Dr. Fine said, including those focused on fifth-generation.

4 . So, you want to learn how to get the most out of your reading experience. Reading effectively is a piece of cake whether you’re reading for school or fun. The following tricks will not only help you comprehend the information you’re learning, but make the reading experience much more enjoyable.

Get a preview of what’s to come by flipping through the pages. Once you have the basic idea of what you’re reading, scan through the table of contents and headers or flick through the pages. Glance over any images, graphs, or illustrations.     1    

Practice active reading by taking notes. Before grabbing your notebook, wait until you’ve finished reading or skimming through a complete section or idea.     2    . Be sure to include the page number and source you’re summarizing in your notes so that you can refer to the text later.

    3     Once you reach the end of a main idea, section, or chapter, take a few moments to let everything soak in before you get back to reading.     4     Identify the author’s bias, assess the evidence, and observe your immediate reactions. Ask yourself whether you agree with the position that’s being presented or the direction of the plot.

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Link what you read to your existing knowledge or past experiences. Instead of treating the text as an isolated piece of writing, link it to previous readings. If a plot point reminded you of something from your own life, make a mental note of it. If you can connect the examples in the journal article with something you learned in class, jot down those similarities.

5 . Researchers believe they have found evidence for a hidden ocean on Mimas, one of Saturn’s major moons. This makes Mimas a target for learning more about the origins of life in our solar system.

Saturn has 146 moons orbiting it. The biggest is larger than the planet Mercury; the smallest is roughly the size of a sports field on the Earth. Mimas, which was first discovered in 1789, is one of the major moons and is about 250 miles wide.

Experts used to think Mimas was mostly made out of solid ice and rock. In 2014, astronomers noticed its orbit around Saturn was moving unsteadily. A shaky orbit can be caused either by a core shaped like a rugby ball or a huge liquid ocean beneath the surface. At first, lots of astronomers argued against the suggestion that Mimas had an ocean because there is no sign of it on the surface.

To investigate more thoroughly, researchers looked at images taken by Cassini, a NASA spacecraft sent to study Satun. The images showed that the moon’s orbit around Saturn drifted by about six miles over 13 years. The team’s calculations found that the only way Mimas could move in this way is if it had a hidden ocean under the surface. They think the ocean formed when the moon’s core warmed up and melted some of the ice.

Mimas is just one of many moons that scientists think could have oceans below the surface Ganymede, which orbits Jupiter and is the largest moon in the solar system, has more water in its ocean than all of the oceans on the Earth. Titan, another of Saturn’s moons, is believed to have a salty ocean beneath the surface.

Space agencies want to study these oceans because they might be home to living organisms. However, the ocean on Mimas might not be old enough for life to have emerged there yet. It took hundreds of millions of years for life to develop on the Earth and the ocean on Mimas is relatively young; it is less than 25 million years old.

7 . A shadowy figure sits alone in a room, his face dimly lit by a computer screen. With a grin, he types in a series of computer commands, and in the blink of an eye, someone’s bank account is drained to zero.

In today’s digital age, cyberattacks like this happen thousands of times per day. Hackers can steal money, information, or completely take control of a machine from anywhere in the world. However, not all hackers are villains.

Some hackers, called white hat or ethical hackers, are individuals who make the most of their hacking skills to identify security vulnerabilities (漏洞) in hardware, software and networks. Their job is crucial in preventing cyberattacks and safeguarding sensitive information. The term “white hat” originated from old cowboy movies, where heroes wore white hats and villains wore black ones. Like the heroes in cowboy movies, white hats seek to stop the bad guys and save the day.

White hat hackers only seek vulnerabilities legally, often working on open-source software or with authorized access to systems. Once these weak spots are identified, companies or individuals can take steps to prevent serious breaches and losses. White hat hackers use a variety of different techniques to keep the internet safe. Penetration testing, for example, allows them to mimic cyberattacks and uncover system weaknesses. Security scanning tools allow white hats to identify holes in a network’s security systems. Simulating denial-of-service attacks (DoS attacks) helps companies prepare for attacks against their websites.

Many of the world’s top white hat hackers began their journeys on the wrong side of the law. A prime example is Kevin Mitnick. This notorious hacker once held the title of “most wanted hacker” in the U. S. due to his cybercriminal activities in 1995. However, after being arrested and spending five years in jail, his life took a remarkable turn. Mitnick decided to use his hacking skills for ethical purposes, eventually establishing his own cybersecurity consulting company.

If you aspire to be a white hat hacker, start by building a strong foundation in computer and network fundamentals. Good luck, computer cowboy!

10 . European wildcats could be reintroduced to England more than 200 years after they became extinct in the country. The project has been announced by UK wildlife charity Wildwood Trust.

European wildcats are one of the UK’s rarest mammals. The only wild population, numbering fewer than 300 individuals, lives in the Scottish Highlands but they are on the verge of extinction, partly because they have bred with local feral cats (wild-living domestic cats).

Supporters hope to save the species in the UK by reintroducing them to England and Wales, where they died out around 200 years ago because of hunting and loss of habitat. To bring back the species, Wildwood Trust is planning to build 10 new breeding facilities on two sites in Kent and Devon. Kittens bred in captivity but away from humans will then be released into the wild. The University of Exeter is researching places where the animals could be reintroduced.

European wildcats are around the same size as a large domestic cat, but at up to eight kilograms they are slightly adult heavier. They have a tabby-like pattern with thick black stripes on their bodies and a bushy tail and like to live in forests but near open grassland. They’re also famously shy and keep their distance from humans. Laura Gardner, director of conservation at Wildwood Trust, told The Times newspaper that people should not be worried by the thought of wildcats returning to the wild. “We’re not talking about wolves,” she said.

Wildwood Trust says that its project can benefit both the wildcats and the habitats where they live. They are one of the few native predators left in the UK, so a healthy population of wildcats could help to control the numbers of animals they prey on, such as rabbits and rodents. By competing for the same food as foxes, they will also help to reduce fox numbers and restore a balance to nature.