When Luke went to university he thought he would be on a new journey in life and getting his own place. In the UK, it's common to fly the nest at a fairly young age. Many choose a flat-share; others make plans to get on the property ladder.

    But the current economic situation forced Luke back to his mum's house at the age of 27. And he's not alone: a quarter of young adults in the UK now live with their parents. The Office for National Statistics said more than 3.3 million adults between the ages of 20 and 34 were living with their parents in 2013.

    Lack of jobs and the high cost of renting accommodation made Luke change his plans. He's upset. "There's something very difficult about being an adult living in an environment where you're still a child," he says. "It limits me socially; sometimes I feel it limits me professionally."

    Indeed, many young people have no choice but to stay at "the hotel of Mum and Dad".

    Krissy had to return home after a year away and now lives in rather terrible conditions, sharing the family's three-bedroom house with her sisters. She says they end up getting on each other's nerves when it's time to use the bathroom in the morning.

    Of course, living with your parents is not unusual in some countries. Economic conditions, culture, or family traditions mean many young people stay at home until they get married. Even then, it can be too expensive to rent or buy a house and the married couples continue to live at one of their parents' homes.

    But some parents seem to enjoy having their kids back at home. Janice's daughters are part of what's being called "the boomerang generation". She says, "I get to share their lives with them, and I've got to know them all as adults. We have the sort of conversations that good friends do."

    So for some it's a win-win situation — spending time with your families, and saving money.

    All too often, a choice that seems sustainable(可持续的)turns out on closer examination to be problematic. Probably the best example is the rush to produce ethanol(乙醇) for fuel from corn. Corn is a renewable resource —you can harvest it and grow more, almost limitlessly. So replacing gas with corn ethanol seems like a great idea. 

    One might get a bit more energy out of the ethanol than that used to make it, which could still make ethanol more sustainable than gas generally, but that's not the end of the problem. Using corn to make ethanol means less corn is left to feed animals and people, which drives up the cost of food. That result leads to turning the fallow land –including, in some cases, rain forest in places such as Brazil—into farmland, which in turn gives off lots of carbon dioxide (CO) into the air. Finally, over many years, the energy benefit from burning ethanol would make up for the forest loss. But by then, climate change would have progressed so far that it might not help.

    You cannot really declare any practice “sustainable” until you have done a complete life-cycle analysis of its environmental(环境的) costs. Even then, technology and public keep developing, and that development can lead to unforeseen and undesired results. The admirable goal of living sustainably requires plenty of thought on an ongoing basis.

    Alexa is a form of artificial intelligence, or AI for short. Many people start their mornings by asking Alexa for the weather forecast or the latest news. A device(设备) that houses Alexa can also play music from your favorite playlists, keep a shopping list, order takeout food, answer questions, send messages and even run “smart” home controls.

    Training AI systems to respond to problems with human-like intelligence and learn from their mistakes can take months, or even years. Consider Alexa and similar software, such as Apple's Siri. To do the tasks its human owners ask, these systems must make sense of and then respond to sentences such as, “Alexa, play my Ed Sheeran playlist” or “Siri, what is the capital of India?”

    Computers can't understand language as it is spoken by people. So AI researchers must find a way to help humans communicate with computers. The technology used to get computers to “understand” human speech or text is known as natural language processing. By natural language, computer scientists refer to the way people naturally talk or write. To teach an AI system a task like comprehending(理解) a sentence or responding to a person 's last move in a board game, scientists need to feed it lots of examples.

AlphaGo is an AI system designed by Google that has beaten a human champion, Lee Sedol, at the strategy(策略) board game Go. To train AlphaGo, Google had to show it 30 million Go moves that people had made while playing the game. Then AlphaGo used what it learned to analyze those plays as it played against different versions (版本) of itself. During this practice, the program came up with new moves—ones never seen in games between people.

A huge lake of salty water appears to be buried deep in Mars, scientists reported this week. The presence of water raises the chances of finding life on the red planet. The discovery is based on observations by a European spacecraft. It has excited experts. Water is necessary for life, and scientists have long hoped to prove that it is present on Mars.

Cassie Stuurman is a geophysicist at the University of Texas. In 2016, she found evidence of a huge ice deposit(沉积)on Mars. “If these researchers are right, this is the first time we've found evidence of a large water body on Mars. ”Stuurman said. Researchers are not yet sure how deep the area of water is. So, they cannot say whether it is an underground pool, or just an area of soft and wet soil.

In order to find the water, Italian researchers examined radar signals. The signals were collected over three years by the European Space Agency's Mars Express spacecraft. The results suggest that a 20-kilometer-wide water body lies below ice that is 1.5 kilometers thick. They believe the area is close to the planet's southern pole.

    Mars is very cold, but salt in the water may have kept it from freezing. It is the same as when you put salt on a road to prevent ice from forming. The water would be extremely cold, right at the point where it's about to freeze. And it would be salty. Such conditions are not ideal for life to form. But, she said there are bacteria on the earth that have been able to survive in similar conditions.

Mars has been a popular planet for exploration, with some groups placing instruments on its surface and others examining it from space. In May, NASA launched another spacecraft, the InSight Mars lander which will dig deep into the data under the surface after it reaches a flat area of the planet in November.

Students, teachers, and local community members are strongly encouraged to register online to receive real-time information of emergency events from Columbia University.

Text message warnings will only be used in rare cases where ongoing events cause an immediate threat or have a significant influence. Possible situations include severe weather conditions, emergency campus closures, crimes in progress that may endanger the community, and major transportation interruptions.

Read instructions on how to sign up for emergency notifications (通知).

Columbia students

Columbia students can easily register for text message notifications. Simply enter Student Services Online, click on "Text Message Enrollment" and add your cellphone number. Students can register parents or family members by following the instructions for the public below.

Columbia teachers

Columbia teachers can register for text message notifications by following the step by step instructions below:

● Register with your UNI and password at my. columbia. edu.

● Select "Faculty & Staff" at the top of the page.

● Select "Contact Details".

● Click the "+" under "Phone".

● Select "Campus Alert 1".

● Enter your mobile number.

To receive emergency information on additional mobile phones, you may follow the above instructions for "Campus Alert 2" and "Campus Alert 3" for a total of three.

Community/General Public

Community/General Public interested in receiving emergency information from Columbia can sign up by clicking on the "Register" button on the registration page and entering their email and mobile number. Users will receive confirmation code (密码) on their phone and will need to confirm their account via email.

Users can choose not to use the Emergency Text Alert System at any time by texting STOP to 226787, calling 226789 or sending an email to lr27682@. cumc. columbia. edu.

As online learning becomes more common and a mass of resources are changed to digital form, some people have suggested that public libraries should be shut down and everyone should be given an iPad with an e-reader subscription (订阅). They believe that it will save local cities and towns money, provide more materials and encourage more people to read.

 However, it would be a serious mistake to replace libraries with tablets (平板电脑). First, digital books and resources are related to less learning and more problems than print resources. A study found that people read 20-30% slower on tablets, keep 20% less information, and understand 10% less of what they read. Additionally, staring too long at a screen has been shown to cause more health problems than reading print does. 

Second, it is incredibly narrow-minded to believe that the only service libraries offer is book lending. Libraries have lots of benefits, and many are only available if the library has a physical location. Some of these benefits include acting as a quiet study space, giving people a way to communicate with their neighbors, holding classes on a variety of topics, providing jobs, answering visitor questions, and keeping the community connected. One neighborhood found that, over a third of residents reported feeling more connected to their community after a series of local library instituted community events. Similarly, a survey conducted in 2015 found that nearly two-thirds of American adults feel that closing their local library would have a major effect on their community.

While replacing libraries with tablets may seem like a simple solution, it would encourage people to spend even more time looking at digital screens and end access to many of the benefits of libraries. In many areas, libraries are such an important part of the community network that they could never be replaced by a simple object.