Two members of the World Health Organization (WHO) new coronavirus traceability international expert group who originally planned to come to China are stranded in Singapore due to the positive test of the new coronavirus antibody. The remaining 13 expert group members have arrived in Wuhan on January 14.
On January 14, the World Health Organization announced on its official social media account that 15 members of the World Health Organization’s International Expert Group on the Traceability of New Coronavirus had received multiple new coronavirus nucleic acid tests and serum antibody tests in their respective countries before departure. After arriving in Singapore, they received a nucleic acid test and serum antibody test again. The nucleic acid test results of 15 people were all negative, but the serum IgM antibody test of 2 of them was positive. The two people are currently undergoing serum IgM and IgG antibody testing again in Singapore.
The World Health Organization said on the 14th that 13 experts from the World Health Organization’s International Expert Group on the Traceability of the New Coronavirus arrived in Wuhan, China on the same day. They will begin work after a two-week quarantine.
In the previous press conference of the Joint Prevention and Control Mechanism of the State Council, Zhang Xiaoguang, deputy director and researcher of the Academician Zeng Yi Laboratory of the Institute of Viral Disease Control and Prevention of the Chinese Center for Disease Control and Prevention, explained that after a person is infected with the new coronavirus for a period of time, it is generally 7-10 days later. , The human body will produce specific antibodies against the virus. The first appeared IgM antibodies, followed by IgG antibodies, so the use of immunological detection methods can detect these specific antibodies to determine whether the human body has been infected with the virus.
“A positive nucleic acid indicates the presence of viral nucleic acid in the specimen, which means that the infected person may be infectious. A positive IgM antibody indicates that the patient is at an early stage of infection, and a positive IgG antibody indicates that he has been infected with the new coronavirus, but it is uncertain whether it is infectious.” Zhang Xiaoguang introduced.
On January 13, the spokesperson of the National Health Commission Mi Feng stated at a press conference of the Joint Prevention and Control Mechanism of the State Council that the international expert group of the World Health Organization arrived in Wuhan in accordance with my country’s prevention and control measures. Corresponding isolation is required. During this period, Chinese scientists and medical experts will conduct in-depth communication with the international expert group through video.
“The traceability of the new coronavirus is a scientific issue. The WHO will also conduct similar investigations in other countries and regions as necessary. China is also willing to continue to cooperate closely with the WHO and international experts on this issue to help trace the source of the global new coronavirus contribute.” Mi Feng said.
Tianwen-1 completed the fourth midway correction of its orbit and returned the first image of Mars
At 20 o’clock on February 5, 2021, the engine of the first Mars exploration mission Tianwen-1 probe was ignited, and the fourth midway correction of the ground fire transfer section was successfully completed to ensure that Mars capture was carried out as planned.
Up to now, Tianwen-1 has been in orbit for about 197 days, about 184 million kilometers away from Earth, about 1.1 million kilometers away from Mars, and a flight mileage of about 465 million kilometers. The probe systems are in good condition.
Prior to this, Tianwen-1 acquired the first Martian image at a distance of about 2.2 million kilometers from Mars.
The potential mass range of dark matter is narrowed, helping to focus the search area
According to a report by the physicist organization network on the 27th, British scientists used the fact that gravity acts on dark matter to fundamentally calculate the mass range of dark matter for the first time. This range is much narrower than previously thought. The latest research has narrowed the range of potential masses of dark matter particles and also limited the search range for future dark matter “catchers”. It will also help scientists discover potential new forces in the future.
Dark matter does not emit light, emit electromagnetic waves, does not participate in electromagnetic interactions, and cannot be directly “seen” with any optical or electromagnetic wave observation equipment. Scientists have confirmed its existence through the effect of dark matter on galaxies. The result of the cosmic microwave background radiation observation experiment gives the proportion of dark matter in the total amount of cosmic matter. In the universe, ordinary matter accounts for only 4.9%, dark matter accounts for 26.8%, and dark energy accounts for 68.3%. Dark energy and dark matter are also considered to be two dark clouds in the physics sky at the beginning of the 21st century.
In the latest study, the research team led by Professor Xavier Kalmot of the School of Mathematics and Physical Sciences at the University of Sussex assumed that gravity is the only force acting on dark matter, and calculated that the mass of dark matter particles is between Between 10-3eV (electron volt) and 107eV, it is much narrower than the theoretically expected 10-24eV to 1028eV.
“This is the first time anyone has used quantum gravity to calculate the mass range of dark matter,” Carmott said. This study shows that unless there is a hitherto unknown force affecting it, dark matter cannot be like some theories. It is said to be “ultralight” or “overweight”.
The researchers believe that this research will benefit physicists in two ways: one is to focus on the search area of dark matter; the other is to help reveal whether there are mysterious unknown forces in the universe-if the mass of dark matter is found to exceed in the future The range predicted by the Sussex team indicates that dark matter is affected by other forces in addition to gravity.
The collapse of some marine species: sea surface temperatures continue to rise under multiple pressures
A zoology study published on the 28th in the British “Nature” magazine pointed out that some marine species are facing a crisis of “population collapse”-since 1970, the number of marine slatyfish in the world has decreased by 71%. Among these marine species, More than three-quarters of them are on the verge of extinction; and another study published at the same time pointed out the “climate crisis” of the ocean: global sea surface temperature has been rising for the past 12,000 years.
The ocean is facing multiple pressures. Issues such as climate change, rising sea temperature, pollution, overfishing, and ocean acidification have been affecting the health of the ocean. Scientists currently believe that the risk of marine species extinction should mainly come from overfishing. However, the reduction of individual species has always been difficult to measure. Although the reduction of marine and coastal plategill fish populations in different regions of the world has been recorded before, there has been no global development. analysis.
This time, the Simon Fraser University team in Canada estimated the relative abundance of 18 marine slaty fish species from 1970 to 2018 and assessed the extinction risk of all 31 marine slaty fish species. They found that from 1970 to 2018, the global abundance of marine slaty fish fell by 71.1%. Among these 31 species, 24 are on the verge of extinction; 3 shark species have declined especially, and are now classified as critically endangered—this is also the most threatened species in the World Conservation Union (IUCN) list The grade.
The researchers blamed the reduction of these species on fishing pressure, which increased 18 times during this period. The research team pointed out that immediate action should be taken to prevent “population collapse”, and specifically called on governments to implement fishing restrictions to help promote species recovery.
In the climate report published on the same day by the journal Nature, the Rutgers University of New Jersey team pointed out the “climate crisis” of the ocean. According to the report, the global average annual sea surface temperature has been rising for the past 12,000 years.
The researchers reinterpreted the two latest climate models this time and devised a method to assess the seasonal deviation of a single record, and then calculate the annual average sea surface temperature. They found that climate warming from 12,000 to 6,500 years ago was caused by the retreat of the ice sheet, while recent warming was caused by the increase in greenhouse gas emissions. The current temperature is the highest in the past 12,000 years. The temperature was similar during the last interglacial period about 125,000 years ago.
In addition to suggesting that emissions have caused the sea surface temperature to continue to rise, this study also fills a long-standing gap in the gap between climate models and data used to reconstruct historical climate changes in the Holocene.