What would you most like to do if it snows? Do science popularization! ｜ Expo Daily

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What would you most like to do if it snows? Do some science!

For example, snow accumulation and snowfall are two different concepts. Snow accumulation refers to the snow covering more than half of the visible area of ​​the land.

Snowfall refers to when the temperature in the clouds is too low and small water droplets freeze into ice crystals, which remain as snowflakes when they fall to the ground. Snowfall observations mainly refer to the amount of snowfall, which is measured by a rain gauge after the snow collected within 12 or 24 hours melts into water.

Also, although both are snow, there are two types of snow: dry snow and wet snow. Dry snow is generally found in Northeast China and Xinjiang. It contains only ice and air, but no water. This type of snow is called dry snow. Wet snow is mostly found in the south, and refers to snow with a water content of more than 5%.

Then, snow can be divided into new snow and old snow. New snow is snow that has fallen within 1-2 days and is very soft. Microwave measurements can penetrate more than 3 meters through it. Old snow is generally accumulated over 1-2 months and is more compacted, so microwave measurements can only penetrate about 1 meter through it.

I have finished popularizing the questions, and I am just waiting for the snow to fall...

Image source: pixabay

Jumping and taking off consumes less energy, and can not only fly but also run~

The robot RAVEN has bird-inspired legs designed by researchers, which can jump and take off, as well as walk on the ground and overcome obstacles. The design, described in the December 5 issue of Nature, could allow people to use flying vehicles in complex terrain.

Birds have legs that can perform a variety of functions, such as walking, hopping, striding, and taking off by leaping. These capabilities are expected to be applied to flying robots, but it is difficult to build a system with multiple motion modules because the mechanical structure of such a system may be too complicated and the system itself may be too heavy, resulting in the aircraft being unable to take off smoothly.

Foreign researchers overcame these difficulties and developed RAVEN. The robot's limbs can move like a bird. The structure of these limbs simulates the hip, ankle and foot, but the overall design is not as complex as the multi-segment leg anatomy seen in birds.

RAVEN can take off by jumping like a bird, which greatly increases the initial flight takeoff speed and is more energy-efficient than taking off without jumping. This leg design can also switch between multiple movement gaits, such as walking, jumping over gaps, and jumping onto obstacles.

The researchers said that although the system still needs further optimization, inspired by the design of RAVEN's legs, it is expected that robots that can use multiple movement modes and have more functions will be designed in the future.

Image source: EPFL NEWS

Are tonsils and appendix really useless?

Have you ever thought about this question: Are tonsils really "residual organs" in the process of human evolution? Existence often means rationality. These organs that seemed redundant in the eyes of people in the past are actually not useless.

Tonsils play an important role in our immunity when we are children, and a recent study shows that the impact of tonsils may not be limited to this. Scientists conducted a 10-30 year follow-up survey on 1.2 million Danish children who had their tonsils removed or retained, and found that 5% of children who had their tonsils removed before the age of 9 were 2-3 times more likely to suffer from respiratory diseases than the general population.

At the same time, these children without tonsils are also more likely to suffer from allergies and diseases such as asthma. Perhaps tonsils play a role in our immunity when we are young, and there are lasting effects on the immune system.

The appendix is ​​similar to the tonsils and has unexpected functions. A 2007 study pointed out that when the intestinal flora is imbalanced, the appendix can supplement the intestinal flora as a safe house for probiotics.

Another study four years later supported this claim, showing that patients who had their appendix removed were more than twice as likely to be infected with Clostridium difficile as the general population because their intestines lacked beneficial bacteria to fight the rapid reproduction of harmful bacteria.

Image source: rh.gatech.edu

When I eat konjac, it always splashes onto my clothes.

Is it really because my hands are unsteady?

First of all, as a liquid, when red oil is squeezed in the packaging bag, due to the fluidity of the liquid, it will look for a pressure release path, that is, the opening of the packaging we tore open, so it is easy to splash out.

In addition, the surface tension of the liquid causes the red oil to form a thin film inside the closed package. When the package is torn open, this film will be destroyed and the red oil will splash out.

Moreover, the harder we squeeze the tripe or other hollow areas in the packaging bag, the higher and farther the red oil will fly. Because the pressure difference between the inside and outside becomes larger, the internal pressure is quickly released when the package is opened, and this "quickness" is reflected in the high and far red oil splashing.

If you open a small hole first, this approach can reduce the outlet area of ​​the red oil, reduce the possibility of red oil splashing, and give the red oil a certain amount of time to adjust its surface tension, while allowing the pressure to be gradually released (the same applies to slow-tear packaging).

Therefore, the correct way to do it is to squeeze the vegetarian tripe and red oil inside to a position away from the opening, then make a small hole in the bag at a lightning speed, and then tear a large hole in the bag diagonally, or slowly tear the large hole after emptying the bag.

Image source: Konjac Shuang official account

Kuafu-1 satellite captures solar prominence eruption

A solar prominence is a huge cloud of gas that is affected by the sun's magnetic field and binds various particles inside like magnetic lines. Once this coil is broken, a large amount of energy will explode outward in the form of high-energy particles.

The content is compiled from China Science Popularization Expo Weibo, China Science Daily, Science Academy, Institute of Physics, Chinese Academy of Sciences, and CCTV Records

This article was first published on China Science Expo (kepubolan). Please indicate the source of the public account for reprinting