1 . A new study suggests that long periods in space can cause the human heart to shrink (缩小). The study—by a team of American researchers—comes as the U.S. makes plans to build a long-term base on the moon and prepares to send astronauts to Mars.

Part of the study was based on the experiences of the retired astronaut Scott Kelly. The U.S. space agency NASA says that during his career, Kelly spent more time in space than any other American astronaut. One of Kelly’s stays aboard the International Space Station (ISS) lasted 340 days. Researchers from the University of Texas Southwestern Medical Center (UT Southwestern) in Dallas collected and analyzed the physical data during Kelly’s long stay aboard the ISS. The goal was to learn the effects of weightlessness on heart health and performance. The team found that during Kelly’s stay in space, the left ventricle (心室) of his heart shrank about 0.74 grams per week.

Dr. Benjamin Levine is a professor at UT Southwestern. He was the leader of the research. In a statement, he explained that because of the conditions in space, the heart does not have to work as hard to pump (输送) blood uphill from the feet. Over time, this can cause shrinkage. In an effort to keep their hearts and bodies healthy in space, astronauts are required to perform different kinds of exercises throughout their stay.

Reductions in heart size are also seen in patients who spend long periods in bed because they are lying flat and the heart does not have to work as hard to pump. A second part of the study examined data from a long-distance swimmer who spent nearly a year trying to cross the Pacific Ocean. The swimmer, Benoit Lecomte, was chosen because he swam more than 2,800 kilometers over 159 days. Levine says long-distance swimming has similar effects on weightlessness. The study showed that during Lecomte’s swim, his left heart ventricle shrank about 0.72 grams per week.

5 . “Tooth loss and gum disease, which is inflammation (发炎) of the tissue around the teeth that can cause shrinkage (萎缩) of the gums and loosening of the teeth, are very common, so evaluating a potential link with brain diseases is incredibly important. Our study found that these conditions may play a role in the health of the brain area that controls thinking and memory, giving people another reason to take better care of their teeth,” said study author Satoshi Yamaguchi, Ph.D. of Tohoku University in Sendai, Japan.

The study involved 172 people with an average age of 67 who did not have memory problems at the beginning of the study. Researchers found that the number of teeth and amount of gum disease was linked to changes in the left hippocampus of the brain. For people with mild gum disease, having fewer teeth was associated with a faster rate of brain shrinkage, which was the same for people with severe gum disease having more teeth. After adjusting for age, researchers found that for people with mild gum disease, the increase in the rate of brain shrinkage due to one less tooth was equal to nearly one year of brain aging. By contrast, for people with severe gum disease, the increase in brain shrinkage due to one more tooth was equal to 1.3 years of brain aging.

“These results highlight the importance of preserving the health of the teeth and not just maintaining the teeth,” Yamaguchi said. Though the study does not prove that gum disease or tooth loss causes diseases like Alzheimer’s, it only shows an association. Yamaguchi added, “Future studies are needed with larger groups of people.” The current experiment involved only a small group of people in one region of Japan, and that too from one particular region of the world.

LEGO has been around forever and is still a favorite toy for children of all     1     (age). Now, however, one teenager has found another use for LEGO, which could help improve the lives of people     2     are missing limbs (手臂).

David Aguilar, a 19-year-old from Spain,     3     (bear) without a right forearm. He was only 9-year-old when he managed     4    ( make) a prosthetic arm (义肢) for himself out of LEGO. Though this LEGO arm was helpful for David, it was not very strong. It wasn’t until nine years later that David was     5    (eventual) able to make another prosthetic arm. It was so strong     6    he could do pushups with it!

Now,     7    (be) a student at Universitat Internacional de Catalunya, David studies bioengineering. In the coming years, David is hoping to make other much     8    (cheap) prosthetics to give more people access to them around the world. He loves using his LEGO arm, and he wants other people who are missing limbs to experience     9     same thing!

It’s so refreshing to see such a clever young man who tries to help others in similar situations     10     his own! We can’t wait to see what David creates in the years to come!

10 . In English it’s common to say, “I know this town like the back of my hand!” While we may know our towns really well, how well do we actually know our hands?     1    

Matthew Longo and his team from University College London studied the left hands of 100 people. With their hands placed palms down under a board, Longo’s team gave the instruction to point to their knuckles (指关节) and fingertips with a marker pen. How did they do? Not that well.

In the experiment, according to Longo, “people think their hands are wider than they actually are.”     2     They were most accurate when finding their thumbs, but became less accurate with each finger, up to their pinkies (小指).

“It is connected to our sense of position,” explained Longo. Humans know where different parts of our bodies are, even if we can’t see them. It tells us whether a joint (关节) is straight or not.     3    So the experiment the team conducted was to find those maps.

    4     On the basis of the study, in our brain’s map, brains “see” areas based on our sense of touch. The stronger the sense of touch in a specific body part is, the bigger that body part seems. An example is our lips. As they have more nerves than our noses, our brain’s map shows our lips are bigger.     5     If you’ve ever had something stuck in your teeth, it probably feels huge! That’s because our tongues also have lots of nerves.