One of the most dangerous insects you need to watch out for during summer is mosquitoes. But no matter how you try to avoid them, some naturally attract mosquitoes more than others.

One of the most important facts to remember is that mosquitoes track people down by smell and body odour (气味), according to Bart Knols, PhD, a biologist devoted to the study of mosquitoes. The carbon dioxide people breathe out, along with chemicals from the skin, creates an “odour plume” that mosquitoes can detect from up to almost 100 feet away. “Each person gives off more than 300 chemicals from the skin, more than 100 in breathing out,” Knols says.

The specific mixtures on the skin that mosquitoes respond to vary by species. The yellow fever mosquito and Asian tiger mosquito, for example, respond well to lactic acid from skin. African malaria mosquitoes respond to a mix of fatty acids, according to Knols. Your individual mixtures and smells determine how much of a mosquito attraction you are, depending on the mosquito species. The mix of chemicals you produce is only partly in your control. These chemicals depend on your genetic make-up, health condition, diet, skin pH, and so on. “Bacteria on the skin break down the mixtures that we give off through our pores (毛孔), and these are the attractive smells,” Knols says. “So it is not actually we that draw mosquitoes, but the bacteria on our skin.”

Although this is a complex and partly understood phenomenon, Knols says that we do all have a unique smell. There are many folk stories about why some people are more or less attractive to mosquitoes. Some people falsely think the blood type is the cause? and others believe taking vitamin B or eating garlic makes people less attractive to mosquitoes—but Knols notes there’s no scientific data backing up these claims.

Experts believe the best time to teach kids language skills is when they are babies. Actually the task is easily done with parents reading or talking to their babies. However, that is impossible when kids are born deaf.

In that case, parents either have to quickly become adept at sign language or risk the child facing learning delays in the future. Now, a lovely blue-eyed robot, a human avatar(用户头像), and some high-tech neuroscience(神经科学)may help parents with this important developmental task.

The Robot Avatar Thermal-Enhanced system, or RAVE, is the creation of a team led by Petitto, a scientist at Gallaudet University. The learning begins when the robot’s thermal(热力的)camera, which is focused on the baby’s face, senses small changes in his body temperature, which is associated with awareness. This, combined with the baby’s facial expression, causes the robot to turn its head and guide the baby’s attention to a computer screen.

Here, a human avatar starts to communicate with the baby much like a parent would. For example, if the baby points towards the screen, the avatar might respond, “Are you pointing to me?” and follow that up with a fairy tale, or some necessary social communication, all in sign language. The “conversation” continues until the kid loses interest.

The team, who have been testing the system for three years, found that babies began to move their hands in a way similar to sign language after interacting with RAVE for just a few minutes. Petitto says natural language, whether communicated through speech or sign, starts the same parts of the brain and believes the movement proves the babies are learning the key parts of communication.

Antarctica is the coldest continent, so what is the coldest city in the world? That honor belongs to the Russian city of Yakutsk. Located in Siberia, one of the world’s coldest and most poorly populated regions, Yakutsk is home to around 336,200 people, many of whom work for Alrosa, a company that runs a diamond mine in the city. Temperatures in Yakutsk have reached minus 76 degrees Fahrenheit (minus 60 degrees Celsius). Some residents insist they have experienced much colder days, but they have been unable to prove it because the thermometer (温度计) only reads down as far as -63℃ (minus 81.4℉), according to an interview by the BBC.

However, while Yakutsk is the coldest city, there are other, less-populous permanently inhabited places that are even more freezing. Oymyakon, a Russian settlement of around 500 people, reached a frosty minus 96.2℉ (minus 71.2℃) in 1924. Somewhat surprisingly, Yakutsk and Oymyakon aren’t that close to each other. They are separated by 577 miles (928 kilometers), and a drive from one to the other would take around 21 hours.

So why are these two places so bone-chilling?

“Siberia is so cold due to a combination of high latitude and it being such a large land mass,” said Alex DeCaria, a meteorology professor at Millersville University in Pennsylvania. Global temperature extremes—both high and low—tend to occur over continents because land heats up and cools down faster than the oceans do. In the case of Siberia, snow and ice cover also play a role, as they help keep the region cool by reflecting the incoming solar radiation back into space. This combination of factors has led to the creation of a large, semi-permanent high-pressure zone forming over Siberia in the winter, known as the “Siberian High”, which results in very cold surface temperatures.

With specific reference to the conditions in Yakutsk and Oymyakon, topography (地形学) also plays a part. “These places are in local valleys. Oymyakon, in particular, is surrounded by relatively high mountain ranges,” explained Jouni Raisanen, a senior lecturer at the University of Helsinki in Finland. “The so-called ‘cold air lakes’ easily form under calm winter conditions. These pockets of cold, relatively ‘heavy’ air can become trapped close to the valley bottom, which helps to shelter the cold air lakes from mixing with warmer air,” Raisanen noted.