The world seems gloomy (阴沉的) and gray when you're feeling blue. In fact, being down might even affect how you perceive (感知) the colour blue. A recent study about colour was published in the journal Psychological Science. It shows a direct connection between a person's ability to perceive colour and their emotions.

    Psychologists have long known that emotions can affect the way people perceive things. That's in part because chemicals from your brain might affect how you process what you see. “Color is such an important part of our experience,” says lead author Christopher Thorstenson, a psychologist at the university of Rochester, in New York. There's reason, he says, that sad people commonly describe the world as “colourless” and “gray”, and happy people use words like “bright” and “colorful”.

    In the experiment, the researchers randomly assigned people to one of two groups. People in the sadness group watched a sad scene from The Lion King. Those in the “amusement” group watched a comedy.

    Everyone was then asked to look at red, yellow, green, and blue patches (斑点) that had been changed to a grayish colour. “Some of the patches are pretty difficulty to make out,” Thorstenson admits he says it takes some time to figure out their shade. People were scored on how accurate their colour perception was. Then they completed an emotional evaluation.

    The result? Sad people had a hard time seeing the difference between shades along the blue-yellow colour axis (色轴). But they did not have problems seeing colours in the red-green spectrum (光谱). Thorstenson says this could be the result of an evolutionary need to see red as a response to anger.

    Thorstenson says these results highlight the possible important of dopamine in sight. Dopamine is a chemical that sends signals to the brain. Researchers are hoping to focus more on dopamine in the future. “We know dopamine affects how we see colours, too,” Thorstenson says “How we feel can really influence how we see the world around us” he says.

D

Preparing Cities for Robot Cars

    The possibility of self-driving robot cars has often seemed like a futurist's dream, years away from materializing in the real world. Well, the future is apparently now. The California Department of Motor Vehicles began giving permits in April for companies to test truly self-driving cars on public roads. The state also cleared the way for companies to sell or rent out self-driving cars, and for companies to operate driverless taxi services. California, it should be noted, isn't leading the way here. Companies have been testing their vehicles in cities across the country. It's hard to predict when driverless cars will be everywhere on our roads. But however long it takes, the technology has the potential to change our transportation systems and our cities, for better or for worse, depending on how the transformation is regulated.

    While much of the debate so far has been focused on the safety of driverless cars(and rightfully so), policymakers also should be talking about how self-driving vehicles can help reduce traffic jams, cut emissions(排放) and offer more convenient, affordable mobility options. The arrival of driverless vehicles is a chance to make sure that those vehicles are environmentally friendly and more shared.

    Do we want to copy — or even worsen — the traffic of today with driverless cars? Imagine a future where most adults own individual self-driving vehicles. They tolerate long, slow journeys to and from work on packed highways because they can work, entertain themselves or sleep on the ride, which encourages urban spread. They take their driverless car to an appointment and set the empty vehicle to circle the building to avoid paying for parking. Instead of walking a few blocks to pick up a child or the dry cleaning, they send the self-driving minibus. The convenience even leads fewer people to take public transport — an unwelcome side effect researchers have already found in ride-hailing(叫车) services.

    A study from the University of California at Davis suggested that replacing petrol-powered private cars worldwide with electric, self-driving and shared systems could reduce carbon emissions from transportation 80% and cut the cost of transportation infrastructure(基础设施) and operations 40% by 2050. Fewer emissions and cheaper travel sound pretty appealing. The first commercially available driverless cars will almost certainly be fielded by ride-hailing services, considering the cost of self-driving technology as well as liability and maintenance issues(责任与维护问题). But driverless car ownership could increase as the prices drop and more people become comfortable with the technology.

    Policymakers should start thinking now about how to make sure the appearance of driverless vehicles doesn't extend the worst aspects of the car-controlled transportation system we have today. The coming technological advancement presents a chance for cities and states to develop transportation systems designed to move more people, and more affordably. The car of the future is coming. We just have to plan for it.

    Machines equipped with artificial intelligence (AI) have performed better than human beings in a high-level test of reading comprehension. Two natural language processing tools received higher test scores than humans in recent exams.

    One of the tools is a product of the American software maker Microsoft. The other was created by the Chinese online seller Alibaba Group. The company said that a deep-learning model developed by its Institute of Data Science of Technologies was the first to beat a human score in the reading comprehension test.

    The test is called the Stanford Question Answering Dataset. It was developed by researchers at Stanford University in California. It has over 100,000 questions and answers. They are based on information found in over 500 stories from the Wikipedia website. The answers to all the questions come from the reading material.

    The AI-powered machines were tested on whether they could provide exact answers to the questions after processing large amounts of information.

    Alibaba said its deep neural (神经的) network model received an “Exact Match” score of 82.44 on the Stanford test. Microsoft reported that a team at Microsoft Research Asia had a score of 82.65. It said the human score on the same questions and answers was 82.304. Many research organizations also appeared on the list—all with scores below 82.

    Alibaba said it has already used its reading comprehension model in different parts of its business. For example, the company is using machines to answer many incoming telephone calls from customers. The company says in the future, the technology could enable machines to guide visitors through museums or provide advice to medical patients.

    Microsoft noted that, overall, people are still much better than machines at understanding the complexity and nuances (细微差别) of language.

    Nearly 20 U.S. states have started carrying out former president Barack Obama's Clean Power Plan, which places limits on carbon dioxide emissions from power plants in an effort to reduce the impacts of climate change. The plan has been in legal limbo (边缘) for the past year. Yet scientists have now calculated another outcome of the policy: harm to crop yields (产量) if the plan is cancelled. Along with carbon pollution, coal-fired power plants spew (喷出) pollutants that form what we know as smog. The contribution of smog to increased rates of asthma (哮喘) and premature deaths was already known. The new research estimates the extent to which smog, under air-pollution policies-4n place before the Clean Power Plan, would limit production in 2020 of four major crops: corn, cotton, potatoes and soybeans.

    Led by environmental engineer Shannon L. Capps, now at Drexel University, the team also sketched the extent to which those crop production losses would reduce under three nationwide scenarios (方案). One improved the efficiency of individual power plants. Another modeled a policy similar to the Obama plan, setting state CO₂ emissions goals for the electricity department. A third established a tax on carbon emissions, under which emissions fell the most. But the greatest drop in smog-forming pollutants—and greatest gains in crop yields—came from policies such as the Clean Power Plan.

    Researchers calculated how well each scenario would reduce the potential productivity loss (PPL) of each crop. PPL is a projected value for 2020 and indicates how much crop growth would suffer because of smog. Scenario 2 most closely agrees with results expected from the Clean Power Plan.

    In its early history, Chicago had floods frequently, especially in the spring, making the streets so muddy that people, horses, and carts got stuck. An old joke that was popular at the time went something like this: A man is stuck up to his waist in a muddy Chicago street. Asked if he needs help, he replies, "No, thanks. I've got a good horse under me."

    The city planner decided to build an underground drainage （排水） system, but there simply wasn't enough difference between the height of the ground level and the water level. The only two options were to lower the Chicago River or raise the city.

    An engineer named Ellis Chesbrough convinced the city that it had no choice but to build the pipes above ground and then cover them with dirt. This raised the level of the city's streets by as much as 12feet.

    This of course created a new problem: dirt practically buried the first floors of every building in Chicago. Building owners were faced with a choice: either change the first floors of their buildings into basements, and the second stories into main floors, or hoist the entire buildings to meet the new street level. Small wood-frame buildings could be lifted fairly easily. But what about large, heavy structures like Tremont Hotel, which was a six-story brick building?

    That's where George Pullman came in. He had developed some house-moving skills successfully. To lift a big structure like the Tremont Hotel, Pullman would place thousands of jackscrews (螺旋千斤顶) beneath the building's foundation. One man was assigned to operate each section of roughly 10jackscrews.At Pullman's signal each man tured his jackscrew the same amount at the same time, thereby raising the building slowly and evenly. Astonishingly, the Tremont Hotel stay open during the entire operation, and many of its guests didn't even notice anything was happening.

    Some people like to say that every problem has a solution. But in Chicago's early history, every engineering solution seemed to create a new problem. Now that Chicago's waste water was draining efficiently into the Chicago River, the city's next step was to clean the polluted river.

The ancient Herculaneum scrolls (卷轴)are thought to contain works of important thinkers in ancient Greece. But the scrolls can't be unrolled (打开). Even a light wind threatens to reduce them to dust. The reason is that they were turned into carbon by a natural disaster in A.D. 79.

But now researchers from the University of Kentucky have found a way to look inside the scrolls without having to touch them. They first create a light that is 10 billion times brighter than the sun by taking advantage of a machine. Then they will use the light to go through the Herculaneum scrolls to study and finally read the words recorded on the scrolls. Researchers think it might take them six months to read the scrolls.

This isn't the first time researchers have tried to read the Herculaneum scrolls. Several years ago, scientists from the European Synchrotron Radiation Facility (ESRF) worked on uncovering the mystery using an X-ray beam 100 billion times brighter than anything used in a hospital, This didn't allow scientists to actually read the scrolls, but it allowed them to make one surprising discovery. The scrolls were written in metallic (金属的) ink, a writing technology that scientists didn't know existed at the time the scrolls were penned.

"For a long time, we thought our studies have let us know everything about the ancient ink used to write on scrolls. Now we find it's not the case. This shows that we should tell ourselves it may not be true when thinking we fully know something once some research is done," said Daniel Delattre, one of the study's authors.

The finding wasn't just a historical curiosity. To learn just how special these scrolls are, consider that the thinker Chrysippus in ancient Greece is said to have written over 700 works; but all are lost, with the exception of a few works found in the Herculaneum scrolls. In other words, it's possible that these scrolls represent the only existing complete works left by this great thinker. And who knows what other great works could exist in the scrolls?