Germs(细菌) are everywhere. You can’t see them, but they are on your desk, on your computer, and even in the air!

Like people, germs move around the world. They fly with us on planes. When food, clothes, and other things travel around the world, germs travel, too. Some germs are safe, but some are dangerous. Germs cause illnesses like colds and the flu.

Warmer Weather Brings Germs

The world’s weather is changing. Cooler countries are getting warmer, so insects from hot countries can move there. Some of these insects, like mosquitoes, carry dangerous germs. These germs cause headaches, fever, and can even kill people.

Under Your Skin

Your skin protects you from germs. It stops some germs, but not all. They can enter your body when you eat, or when you have a cut. Germs are on your hands, too. They enter your body when you touch your eyes, nose, or mouth.

Fighting Germs

Your immune system(免疫系统) protects you, too. When germs get inside your body, your immune system finds and kills them. Special cells(细胞) move around your body and fight germs. They help you stay healthy. Other cells make antibodies. Antibodies help your body find and stop germs.

What can you do to fight germs? You should wash your hands with soap and water. Soap kills many germs, and water washes them away.

Can exercise during childhood protect you against memory loss many decades later? Exercise early in life seems to have lifelong benefits for the brain, in rats at least.

“This is an animal study, but it shows that physical activity at a young age is very important — not just for physical development, but for the whole lifelong track of cognitive (认知的) development during ageing,” says Martin Wojtowicz of the University of Toronto, Canada. “In humans, it may delay the appearance of Alzheimer’s symptoms (阿兹海默氏症), possibly to the point of preventing them.”

Wojtowicz’s team divided 80 young male rats into two equal groups, and placed running wheels in the cages of one group for a period of six weeks. Around four months later — when the rats had reached middle age — the team taught all the rats to connect an electric shock with being in a specific box. When placed in the box, they froze with fear.

Two weeks later, the team tested the rats in three situations: exactly the same box in the same room, the same box with the room arranged differently, and a completely different box in a different room.

The rats without access to a running wheel when they were young now froze the same percentage of times in each of these situations, suggesting they couldn’t remember which one was dangerous. But those that had been able to run in their youth froze 40 to 50 percent less in both changed box settings.

“The results suggest the amount of physical activity when we’re young, at least for rats, has influence on brain and cognitive health — in the form of better memories — when we’re older,” says Arthur Kramer of Northeastern University in Boston, who has found that, in humans, exercise promotes the growth of new brain cells.

Marine cold spells are cold versions of heat waves: periods of exceptionally cold water which are able to hurt or help the ecosystems they hit. Today, the oceans experience just 25% of the cold spell days they did in the 1980s, and cold spells are about 15% less intense (强烈的), according to a new study. Weaker cold spells could mean they’re less likely to cause mass die-off events, but having fewer cold spells also means recovery periods from marine heat waves are disappearing.

“Recently, studies have focused more on heat waves and warm ocean temperature events than on the cold events,” said lead author Yuxin Wang, an ocean and climate scientist. “Because marine cold spells have both positive and negative impacts, understanding when, where and why these spells appear is very important for fisheries’ long-term planning.”

Wang and her colleagues analyzed sea surface temperature data from 1982 to 2020, checking for periods of either terribly hot or cold temperatures. They found that oceans are warming, and sea surface temperatures are becoming variable over time. That variability leads the intensities of marine heat waves and cold spells to change at different rates, making it more difficult for scientists to forecast (预测) each.

Establishing global trends in marine cold spells and their relationship to global warming is an important step, but further studies are needed to control regional and local effects. Those local effects include impacts on fisheries. “Marine cold spells play double roles in influencing ecosystems,” Wang said. ”Cold spells can cause terrible impacts. But they can counteract the impacts of heat waves.”

Extreme (极端的) events affect coastal communities and economies, but members of the public might not be aware of how they’re going to intensify in the future. We need to get the word out.” said Darmaraki, a physical oceanographer. “Information about the underlying physical causes of these extreme events can help improve the forecast. That information can be provided for fisheries. The earlier communities know what to expect, the better they can prepare.”