Mosquitoes have an extraordinary ability to find humans far away and fly straight to their skin. Mosquitoes can do more than cause an itchy (发痒的）wound. Some mosquitoes spread several serious diseases, including Dengue, yellow fever and malaria.

    Over one million people worldwide die from these diseases each year. New research now shows how mosquitoes choose who to bite.

    Mosquitoes need blood to survive. They are attracted to human skin and breath. They smell the carbon dioxide gas, which all mammals breathe out. This gas is the main way for mosquitoes to know that a warm-blooded creature is nearby.

    But mosquitoes also use their eyes and sense of touch. Michael Dickinson is a professor at the California Institute of Technology. His research shows how these small insects, with even smaller brains, use three senses to find a blood meal.

    Michael Dickinson's team used plumes—a material that rises into the air of carbon dioxide gas into a wind tunnel (隧道). They then used cameras to record the mosquitoes. The insects followed the plume.

    Then, the scientists placed dark objects on the lighter colored floor and walls of the tunnel. Mr. Dickinson said, at first, the mosquitoes showed no interest in the objects at all. “What was quite surprising is that the mosquitoes fly back and forth for hours. These are hungry females and they completely ignore the objects on the floor and wall of the tunnel. But the moment they get a hit of CO₂, they change their behavior quite obviously and now would become attracted to these little visual blobs (斑点).”

    This suggested to the researchers that a mosquito's sense of smell is more important in the search for food. Once mosquitoes catch a smell of a human or animal, they also follow visual signals.

    Soft winds blew throughout the Windy City today. We welcomed the winds, as it was another hot day in Chicago. The wind blew, bringing us some coolness and making the weather not that hot. But it was a beautiful summer day with a blue sky.

    Chicago is a great city for eating, and we have enjoyed tasting the different foods. Last night, we tried one of the city's most famous foods: deep-dish pizza. Chicago claims credit for the rich and cheesy thick-crust pizza, covered with a sweet tomato sauce. We topped it with olives and green peppers.

    We were touring the city, mainly looking for delicious local foods. Today, we enjoyed a Polish specialty at lunch: Pierogis, an Eastern European dumpling-like dish, filled with foods like potatoes, cheese, mushrooms, cabbage and meat. Polish immigrants started settling in Chicago in the 1850s, and the city has one of the largest Polish communities in the U.S.

    We took a break from exploring the city to talk with some of you! Ashley and Caty logged onto the Internet for an on-the-road version of TALK2US. We spoke to an English teacher in Tokyo, Japan, and a graduate student in India.

    Meanwhile, Adam searched for some locations around the city to shoot some video. He chose a spectacular spot: Navy Pier, Chicago's most-visited attraction. The winds from Lake Michigan keep visitors cool, and the view of the Chicago skyline never fails to impress. In fact, the view made all of us head over heels!

    Our time in Chicago has come to an end. Tomorrow, the true journey begins, as we pass through Illinois and into Missouri via Route 66. Springfield, the home of Abe Lincoln, and St. Louis, the "gateway to the West," wait for us.

    AlphaGo is a computer program that plays the board game Go.

    In March, 2016, the pride of humankind was crushed (粉碎) by a computer. Google's AlphaGo defeated the South Korean grandmaster (围棋大师) Lee Sedol four games to one, as the world looked on with shock and awe (敬畏). Artificial intelligence (AI, 人工智能) had suddenly reached a new and unexpected height.

    But as smart as AlphaGo is, it's no longer the best Go “player” in the world. Google's artificial intelligence group, DeepMind, has created the next generation of its Go-playing program, called AlphaGo Zero. The new AI program is unique in the way it learned to play Go. Instead of learning from thousands of human matches, as its predecessor (前任) did, AlphaGo Zero mastered Go in just two days without any human knowledge of the game and defeated AlphaGo by day three, reported The Guardian. It then went on to defeat AlphaGo 100 games to zero.

    To learn how to play Go, AlphaGo Zero played millions of matches against itself using only the basic rules of the game to rapidly create its own knowledge of it. Like the previous version, it used “reinforcement (增强) learning to become its own teacher,” according to DeepMind's website.

    “It's more powerful than previous approaches,” David Silver, AlphaGo's lead researcher, told The Guardian, “because by not using human data, or human expertise in any fashion, we've removed the constraints (约束) of human knowledge and it is able to create knowledge itself.”

    AlphaGo Zero's approach to self-learning is a significant advancement in AI that could be applied to help solve some of the world's biggest problems, according to a recent research report published in the journal Nature. For example, DeepMind co-founder Demis Hassabis argues that AlphaGo Zero could probably find cures for a number of serious diseases within weeks, according to The Telegraph. Indeed, the AI is now being used to study protein folding, which is connected to diseases such as Parkinson's and Alzheimer's.

    So now that AI has exceeded (超过) the bounds of human knowledge, perhaps the question is not about what AI can learn from humans, but what humans can learn from AI. We can only wait and see.

    The Great Fire of London started in the very early hours of 2 September 1666. In four days it destroyed more than three-quarters of the old city, where most of the houses were wooden and close together. One hundred thousand people became homeless, but only a few lost their lives.

    The fire started on Sunday morning in the house of the King's baker(面包师)in Pudding Lane. The baker, with his wife and family, was able to get out through a window in the roof. A strong wind blew the fire from the bakery(面包房)into a small hotel next door. Then it spread quickly into Thames Street. That was the beginning.

    By eight o'clock three hundred houses were on fire. On Monday nearly a kilometer of the city was burning along the River Thames. Tuesday was the worst day. The fire destroyed many well-known buildings, old St Paul's and the Guildhall among them.

    Samuel Pepys, the famous writer, wrote about the fire. People threw their things into the river. Many poor people stayed in their houses until the last moment. Birds fell out of the air because of the heat.

    The fire stopped only when the King finally ordered people to destroy hundreds of buildings in the path of the fire. With nothing left to burn, the fire became weak and finally died out.

    After the fire, Christopher Wren, the architect(建筑师), wanted a city with wider streets and fine new houses of stone. In fact, the streets are still narrow; but he did build more than fifty churches, among them new St Paul's.

    The fire caused great pain and loss, but after it London was a better place: a city for the future and not just of the past.

    Why does time seem to fly by faster as we get old? You've got your aging brain to blame. This is likely due largely to the physical changes of our nerves and neurons (神经元). New research suggests 'rapid fire' abilities of the young brain allow us to process more information during youth, causing the days to seem longer earlier in life. However, as we get old, researchers say the older brain takes more time to process information.

    The new finding put forward by a Duke University researcher was published in a paper in the journal European Review this week According to Adrian Bejan, the J. A Jones Professor of Mechanical Engineering at Duke, the physical changes of our nerves and neurons play, a major role in our perception (知觉) of time as we get old. Over the years these structures become more complex and eventually begin to degrade.

    "Little babies, for example, move their eyes much more often than adults because they're processing images at a faster rate," Beian says, For older people, this means fewer images are being processed in the same amount of time, causing experiences to seem as though they're happening more quickly.

    "An apple a day keeps the doctor away" is one of the most common sayings in the English languages. This is because apples were one of the first foods that medical professionals recognized as healthy­their benefits became obvious when  quite simply, doctors found that people who ate apples were sick less often than those who did not. Today we have a more specific understanding of why apples are so beneficial to overall health.

    Apples can help keep your levels of bad cholesterol (胆固醇) down. The pectin (果胶) in apples helps you to maintain cardiovascular health and reduce LDL cholesterol(which is the "bad" kind). Apples themselves do not add cholesterol to your diet and are full of water and fiber to help prevent the cholesterol in other foods you might digest. According to Health Diaries, people who eat two apples per day may lower their cholesterol by as much as 16 percent.

    Apples are naturally low in calories and high in water content. Eating an apple can satisfy your hunger and keep you from reaching for high-sugar, high-calories snacks. By eating apples, you will be more able to maintain a healthy weight because they fill you up, potentially stopping you from eating food that encourages a waistline increase.

    Apples contain respectable levels of boron (硼) which helps build healthy bones, and can also prevent diseases like arthritis. Apples are rich in vitamin C, which is known to help build immunity.

    Studies have shown that apples can decrease the risk of breast cancer, colon cancer, and liver cancer. One theory is that the apple skins are responsible for this, so be sure not to peel your apple before you eat them, as you could remove some of the health benefits.