Now, let’s talk about earthquakes on our planet. Some countries have large numbers of earthquakes. Japan is one of them. Others do not have many. For example, there are few earthquakes in Britain. There is often a great noise during an earthquake. The ground vibrates(震动). Houses fall down. Trains run off the lines. Sometimes, there is a heavy loss of human lives.

Earthquakes often happen near volcanoes, but this is not always true. The centers of some earthquakes are under the sea. The bottom of the sea suddenly moves. The powerful forces inside the earth break the rocks. The coast is shaken and great waves appear. These waves, also known as seismic waves(地震波), or tsunamis(海啸) can travel long distances and rush over the land when they reach it. They are strong enough to break down houses and other buildings. Very often fires follow the most serious earthquakes. In 1906, the numbers of fires were burning in the city. The water pipes were also shaken and broken, so it was not possible to put the fire out. There was no water. The Tokyo Earthquake of 1923 happened just before noon. People were cooking meals on their fires at that time. When the ground shook, the fires shook, too. Hot materials were thrown on the different parts of the houses, some of which were made of wood. Soon 134 fires were burning in the city.

What kind of building stands up best in an earthquake? A building with concrete walls is perhaps the best. A steel frame will make it even stronger. The frame holds the different parts together and the walls so not easily fall. There is less chance of fire because concrete and steel do not burn. Over the years, scientists studied the results of the earthquake in different parts of the world, and they are convinced that this kind of building is the safest.

Are you preparing for a big test? If so, you may want to go to play some basketball in between hitting the books. Doctors are starting to find more and more information that suggests a connection between exercise and brain development. Judy Cameron, a scientist at Oregon Health and Science University, studies brain development. According to her research, it seems that exercise can make blood vessels (血管), including those in the brain, stronger and more fully developed. Dr. Cameron is sure that this allows people who exercise to think better. As she says, “While we already know that exercise is good for the heart, exercise can actually cause physical changes in the brain.”

The effects of exercise on brain development can even be seen in babies. Babies who do activities that require a lot of movement show greater brain development than babies who are less physically active. Even a little movement can show big results. Margaret Barnes, a scientist, also believes in the importance of exercise. She thinks that many learning disabilities that children have in primary school or high school can result from a lack of movement as babies. Babies need movement that encourages and excites their five senses. They need to set up a connection between motion and memory. In this way, as they get older, children will begin to connect physical activity with higher learning,” says Margaret.

Older people can develop their brains as well. Cornell University studied a group of seniors who have a short-term memory increase of up to 40 percent after exercising just three hours a week. The exercise does not have to be very difficult, but it does have to increase the heart rate. Also, just like the motion for babies, exercise for older people should not be too simple. Learning some new skills or actions, such as with yoga or taichi helps to open up memory paths in the brain that may not have been used for a long time. For most people, any type of physical activity that increases the heart rate is helpful. The main aim is to increase the brain’s flow of blood. And your brain can benefit from as little as two to three hours of exercise a week.

Co-authored by researchers at the University of Tennessee, Knoxville and Texas A&M, the paper looked at nearly50 years of data testing whether facial expressions can lead people to feel the emotions related to those expressions.

“Traditional wisdom tells us that we can feel a little happier if we simply smile, or that we can get ourselves in a more serious mood if we glare, and frowning makes us feel sadder.” said Nicholas Coles, UT Ph.D. student in social psychology and leads researcher on the paper. “But psychologists have actually disagreed about this idea for over 100 years.” These disagreements became more pronounced in 2016, which are more evident especially when 17 teams of researchers failed to replicate(复制) a well-known experiment demonstrating that the physical act of smiling can make people feel happier.

“Some studies have not found evidence that facial expressions can influence emotional feelings,” Coles said.

“But we can’t focus on the results of any one study. Psychologists have been testing this idea since the early 1970s so we wanted to look at all the evidence.”

Using a statistical technique called meta-analysis, Coles and his team combined data from 138 studies testing more than 11,000 participants from all around the world.

According to the results of the meta-analysis, facial expressions have a small impact on feelings. “We don’t think that people can smile their way to happiness,” Coles said. “But these findings are exciting because they provide a clue about how the mind and the body interact to shape our conscious experience of emotion.” “We still have a lot to learn about these facial feedback effects, but this meta-analysis put us a little closer to understanding how emotions work.” Coles added.