Believe in science

Genetics

Since the 20th century, it has been believed that gene mutation occurs randomly, and the difference of gene frequency appears in the population under the action of natural selection. However, a recent study of Arabidopsis thaliana (Arabidopsis thaliana), published in Nature, challenges this view.

Scientists sequenced hundreds of Arabidopsis lines over a period of three years and found more than 1 million mutations. They found that there were low mutation rates in some key regions of the genome, which contained many genes that affect key biological processes such as cell growth and gene expression. The rate of intra-gene mutations in these regions was halved, while the mutation rates of some key genes were reduced by 2/3. Further analysis showed that the distribution pattern of gene mutation rate was related to epigenetic changes in the genome. The researchers believe that genes that play a key role in life activities are sensitive to potentially harmful mutations, while Arabidopsis thaliana seems to have evolved a protective mechanism that can effectively repair DNA damage in these regions, thereby reducing the mutation rate of these genes, which may be an important driving force of evolution. This study may change people's perception of genetic mutation and evolution.

Astronomy

Found a candidate exosatellite with a radius of 2.6 times that of Earth.

Extrasolar moons refer to celestial bodies orbiting exoplanets, which are very important for understanding the formation and evolution of exoplanet systems. Scientists have found some celestial bodies that may be exosatellites, but they have not yet confirmed the existence of any exosatellites. Recently, a study published in the journal Nature Astronomy found a new candidate for exosatellite.

Using data from the Kepler space telescope, the researchers analyzed 70 extrasolar gaseous giant planets to look for traces of extrasolar moons. The temperature of these planets is lower (less than 27 ℃), the radius of their orbits is greater than the distance between the earth and the sun, and the orbit period is longer than one year. After rigorous screening, the researchers found only one suspected satellite signal around one of the planets, Kepler-1708b. They call the possible satellite Kepler-1708b-i, and its radius is estimated to be about 2.6 times that of Earth. However, there is a 1% chance that this signal is a false positive signal, and further evidence is needed to confirm that the signal does come from an extraneous satellite. The researchers point out that if such large satellites do exist, they will challenge the current theory of satellite formation.

Material science

New carbon-based superconductor materials

Conductors rely on the movement of electrons to conduct electricity, but the movement of electrons will inevitably be hindered by resistance, resulting in the loss of energy in the form of heat. One exception, however, is zero-resistance superconductors. A pair of particles form quantum state condensates at extremely low temperatures, resulting in superconductivity, such as superconductor aluminum and superfluid helium. However, at present, the known superconducting materials must be maintained at very low temperature, which is very difficult to achieve, and the paired particles in the superconductor are negatively charged and repel each other. Recently, in a study published in Science, researchers formed quantum particle pairs of negatively charged electrons and positively charged holes in a strong magnetic field, resulting in superconducting graphene-based materials.

At an ambient temperature of about minus 267 degrees Celsius, the researchers obtained thin layers of graphene rich in electrons and holes in a magnetic field of 10 Tesla. In order to increase the distance between electrons and holes, they also added multi-layer insulated boron nitride between the two graphene thin layers. By changing the thickness of the insulating layer, they can directly control the interaction between particles. In this study, a new particle pairing mode is adopted, which breaks through the obstacle of electron mutual exclusion to condensed matter. They plan to further raise the temperature limit for superconductors in the future.

Astronomy

The largest three-dimensional sky map of the universe has been released.

Physics

The multiverse can explain the small mass of the Higgs particle.

The standard model of particle physics is so successful that it accurately predicts most of the basic interactions and elementary particles in the universe. But there are also some loopholes in this model. For example, it does not contain dark matter particles, does not explain the accelerated expansion of the universe, and does not explain why the theoretical prediction of the mass of the Higgs boson is three times that of experimental measurements. Citing the theory of multiple universes, the two scientists proposed a new model that could explain why the strong interactions between matter and antimatter are so similar in addition to the Higgs boson mass. Their model was recently published in the physical Review KuaiBao.

Scientists assume that multiple universes were born from the beginning, and that each universe contains a different mass, some of which contain the heavier Higgs boson, others contain the lighter one. They found that the region of the universe where the Higgs boson is heavier is so unstable that it only takes about 10-5 seconds to collapse, or a big squeeze. In our universe, the Higgs boson is lighter and is the only one that has survived. At the same time, they found that the symmetry of strong interactions between matter and antimatter is the key to preventing the current cosmic squeeze, which is a loophole in the standard model. The team said their model could be tested in future dark matter and baryon matter experiments.

Zoology

Scientists have discovered the largest known fish nest in the world.

In a study published yesterday in current Biology, researchers said they had found the world's largest known fish nest in the Weddell Sea in Antarctica. In February 2021, the research team began to find many fish nests in the area. They placed a camera system on the ship to capture the undersea world 420 to 535 meters under the ship in real time, especially in extreme environments. They use fiber optics and cables to "swim" the camera through the sea at a speed of 1852 meters per hour, making it about 1.5 meters above the sea floor.

According to this method, they eventually found that there was an average of one fish nest every 3 square meters in this area, and sometimes even one or two fish nests per square meter. Finally, statistics show that there are a total of 240 square kilometers of fish nests in this area, which is almost the size of an European island of Malta. Moreover, it is estimated that nearly 60 million ice fish live in such a large nest. Researchers believe that such a large fish nest in the Weddell Sea in Antarctica is a very important ecosystem here.