The probability of asteroid "2024 YR4" hitting the Earth has dropped to 0.28% | Science and Technology Weekly

Compiled by Zhou Shuyi and Pingsheng

Microsoft claims quantum computing breakthrough, but physicists question it

On February 19, Microsoft announced the launch of the world's first quantum processor based on topological qubits, "Majorana 1", claiming that it "marks a revolutionary step towards practical quantum computing". However, some researchers are skeptical of the company's claims, and the industry expects Microsoft to release more technical details.

Majorana 1 | Microsoft

Majorana zero-energy mode (MZM) is a type of topological non-trivial quasiparticle excitation in condensed matter physics. Because it obeys non-Abelian statistics, the many-body state of the system strongly depends on the exchange operation process, and it is expected to be used as a basic unit for constructing topological quantum bits. Microsoft said that Majorana 1 is built based on topologically protected high-fault tolerance quantum bits, using an Al/InAs nanowire composite structure. When cooled to near absolute zero and controlled by a magnetic field, the collective behavior of electrons exhibits Majorana zero-energy mode characteristics. Majorana 1 integrates 8 topological quantum bits on a chip, and the future goal is to expand to one million quantum bits. It is reported that Majorana 1 is very stable, and on average only one quantum state change caused by external energy destruction such as electromagnetic radiation occurs every millisecond.

Microsoft also published a paper related to Majorana 1 in Nature that day, but this paper was only an intermediate result and did not include some subsequent experiments. The authors of the paper said that the measurement results of the article can only illustrate the non-local correlation characteristics of Majorana zero-energy modes, and did not prove that topological quantum bits do exist. Some researchers criticized Microsoft for not releasing more technical details. "If you don't see additional data from quantum bit operations, there's nothing to comment on," said Georgios Katsaros, a physicist at the Austrian Institute of Science and Technology. Vincent Mourik, a physicist at the Helmholtz Research Center in Germany, was skeptical of the entire study: "Fundamentally, the approach that Microsoft is pursuing to build a quantum computer based on topological Majorana quantum bits will not work."

In 2018, Microsoft's research team in Delft, the Netherlands claimed to have discovered Majorana zero-energy modes, but the relevant paper was retracted in 2021.

The largest AI model in biology released, which can write DNA on demand

On February 19, the AI ​​biology model Evo 2, jointly developed by researchers from the Arc Institute, Stanford University and other institutions and chip manufacturer Nvidia, was officially released. Evo 2 is trained with 9.3 trillion nucleotides from more than 128,000 genome data and is currently the largest AI model in the field of biology. Researchers said that Evo 2 can "read, write and think in the language of nucleotides" and identify patterns in the genetic sequences of organisms that are difficult for humans to find.

Evo 2 was trained on 9.3 trillion nucleotides of data from over 128,000 genomes, a similar scale to the most powerful generative AI large language models. | Arc Institute

DNA and RNA encode biological genetic information, and the patterns in them can be detected and read by AI. "These patterns have evolved over millions of years and contain clues about how molecules work and interact with each other," said Brian Hie, an assistant professor of chemical engineering at Stanford University and an author of the paper. Unlike ordinary AI models that predict protein structure, Evo 2's training data contains both coding and non-coding regions of genes.

Evo 2's predecessor, Evo 1, was released in 2024 and trained on the genomes of about 80,000 bacteria, archaea, and bacteriophages. It can achieve zero-sample function prediction in DNA, RNA, and protein modes, and can generate DNA sequences with a length of more than one million base pairs and a reasonable genome structure. Based on 128,000 genome data, Evo 2 further expands the training scope to plants, eukaryotic organisms such as animals including humans, with training parameters as high as 40 billion (there is also a version with 7 billion parameters).

It is reported that Evo 2 can be used for a variety of tasks. It can identify genetic changes that affect protein function and the adaptability of organisms. For example, in tests on BRCA1 gene variants associated with breast cancer, Evo 2 achieved an accuracy rate of more than 90% in predicting which mutations are benign mutations and which are potential pathogenic mutations. Accelerating the development of new drugs by finding the genetic causes of human diseases can save a lot of time and research funds used for cell or animal experiments. In addition, Evo 2 can also be used to design new biological tools or treatments.

The research team also verified the generation capability of Evo 2, which can generate mitochondrial genome sequences, prokaryotic (bacterial) genome sequences, and eukaryotic (yeast) entire chromosome sequences from scratch, with the naturalness and coherence of the generated sequences being better than previous methods. In addition, Evo 2 can also controllably generate epigenomic structures through inference-time search (dynamically adjusting the search strategy during the AI ​​model inference phase to optimize the output results).

Considering the potential ethical and safety risks, the researchers excluded pathogens that infect humans and other complex organisms from the basic data set of Evo 2, and ensured that the model would not return valid answers to queries related to these pathogens. Currently, Evo 2 is open to researchers around the world, who can use the model through the web page or download the model's source code, training data, and model weights for free. The related preprint paper was published on BioRxiv on February 19.

CAR-T therapy allows malignant tumor patients to survive for 18 years

A neuroblastoma patient who received chimeric antigen receptor T cell (CAR-T cell) therapy has been in remission for more than 18 years without further treatment. Researchers said this may be the longest survival time reported so far in cancer patients treated with CAR-T. The related paper was published in Nature Medicine on February 18.

Neuroblastoma is an extracranial solid tumor originating from the nervous system. It is common in infants and young children, accounting for 8% to 10% of childhood malignant tumors. It is difficult to treat and has a high recurrence rate. CAR-T cell therapy refers to the use of gene modification technology to transfer genetic material with specific antigen recognition domains and T cell activation signals into T cells, so that T cells can play a targeted role in killing tumor cells. This type of therapy has been approved for the treatment of some blood cancers, such as leukemia and lymphoma, but the effect is poor in patients with solid tumors.

Between 2004 and 2009, researchers recruited 19 children with neuroblastoma for a phase 1 clinical trial to test CAR-T cells targeting the neuroblastoma GD2 protein. However, as a first-generation CAR-T therapy, it has not yet embedded the co-stimulatory signaling domain that was commonly used later. Eleven of these children were in active stages of the disease when they received the infusion, and three achieved complete remission after treatment, one of whom subsequently relapsed; one person's complete remission lasted for 8 years until he was lost to follow-up; one person had been in remission for more than 18 years without receiving other cancer treatments, and she also gave birth to two healthy babies.

The remaining eight patients had no cancer symptoms when they received the infusion, and five of them showed no signs of recurrence in the most recent follow-up 10-15 years after treatment. The trial completed its primary goal, which was to test the safety of CAR-T cells, but 12 of the 19 patients died between 2 months and 7 years after the infusion. In addition, including the patient with 18 years of remission, the researchers detected the GD2 CAR gene in the blood samples of five patients, which may mean that the CAR-T cells persisted for at least 5 years.

Karin Straathof, associate professor of tumor immunology at the University College London Cancer Institute, commented: "This is indeed strong evidence that solid tumors can achieve complete remission (through CAR-T). "She believes that further research is needed. "We are working to figure out why it works for some patients and not for others, in order to better design chimeric antigen receptors."

The probability of asteroid 2024 YR4 hitting Earth has dropped to 0.28%

The latest assessment released by NASA on February 20 shows that the probability of an asteroid numbered "2024 YR4" hitting the Earth on December 22, 2032 has dropped to 0.28%. NASA's planetary defense research team will continue to track and observe this asteroid to assess the risk of impact with the Earth.

Recently, the topic of the possible impact of the asteroid "2024 YR4" on Earth has attracted public attention. According to NASA, the asteroid was first discovered by the "Asteroid Earth-impact Last Alert System" in Chile on December 27, 2024, and is expected to be between 40 and 90 meters in diameter.

Since the end of last year, astronomers have been tracking and observing the asteroid and adjusting the analysis data. On the 18th of this month, the Center for Near-Earth Object Studies at NASA's Jet Propulsion Laboratory updated the estimated probability of the asteroid hitting the Earth to 3.1%. This is the highest probability of an object of the same size ever assessed by the agency to hit the Earth. However, in the past two days, NASA has continuously lowered the impact probability, which has now dropped to 0.28%.

NASA said that at present, the probability of asteroid 2024 YR4 hitting the Earth on December 22, 2032 is very small. As more observation data is collected and added to orbital calculations, this probability is likely to drop to zero. After April this year, due to the increasing distance between the asteroid and the Earth, Earth telescopes will not be able to observe it until 2028 when the asteroid approaches the Earth again and is bright enough for further observation and analysis. (Xinhua News Agency)

Chinese scientists discover new type of normal-pressure high-temperature superconductor

A research team jointly formed by the Southern University of Science and Technology, the Guangdong-Hong Kong-Macao Greater Bay Area Quantum Science Center and Tsinghua University published their research results online in Nature on February 18, achieving high-temperature superconductivity of nickel oxide materials under normal pressure, with the superconducting starting transition temperature exceeding 40 Kelvin (K), equivalent to minus 233 degrees Celsius, and observing the dual characteristics of "zero resistance" and "anti-magnetism". This discovery makes nickel-based materials the third type of high-temperature superconducting material system that has broken through the 40K "McMillan limit" under normal pressure after copper-based and iron-based materials, providing a new breakthrough for solving the scientific problem of the high-temperature superconductivity mechanism.

The highest superconducting transition temperature of traditional superconductors is 40K, which is the "McMillan limit". Previously, the superconducting transition temperatures of copper-based and iron-based materials exceeded the "McMillan limit" and were called high-temperature superconductors. In recent years, nickel-based superconducting materials have emerged. How to get rid of the high-pressure limitation and achieve normal-pressure high-temperature superconductivity has become an important research direction in the international scientific community.

In response to this challenge, the research team led by Academician Xue Qikun and Associate Professor Chen Zhuoyu independently developed the "Strong Oxidation Atomic Layer-by-Layer Epitaxy" technology. This technology can achieve layer-by-layer growth of atomic layers under conditions where the oxidation ability is tens of thousands times stronger than traditional methods, and precisely control the chemical ratio, just like "building atomic building blocks" at the nanoscale, to construct oxide films with complex structures, thermodynamic metastable, but perfect crystal quality.

Using this technology, the research team precisely arranged atoms such as nickel and oxygen on an atomically smooth substrate to construct an ultra-thin film with a thickness of only a few nanometers. In addition, through interface engineering, the atomic structure that originally required an extremely high pressure environment to exist stably was fixed in an extremely strong oxidizing environment. Finally, the high-temperature superconductivity of nickel oxide materials was successfully achieved under normal pressure.

Nickel-based superconductor research is a hot topic in the current international scientific community, and global competition is extremely fierce. The research team at Stanford University and its collaborators reported normal-pressure superconductivity in a similar material system almost at the same time. The Chinese and American teams have independent research paths and their experiments confirm each other. The electronic structures of the three types of high-temperature superconductors, nickel-based, copper-based and iron-based, are different. Through comparative studies of the three, we can deeply understand the core mechanism of high-temperature superconducting electron pairing, providing a key to solving the century-old scientific problem of the high-temperature superconductivity mechanism.

Want dessert after a full meal? How did the term "dessert stomach" come about?

After finishing the meal, your stomach is full, but when the dessert is served, do you feel that you still have a stomach that can hold cake, ice cream or fermented rice dumplings? An international team recently discovered that this appetite for dessert is responsible for a group of specific neurons in the brain. Inhibiting the related neural pathways can reduce sugar intake in a full state and help fight obesity and metabolic diseases.

Through experiments on mice, researchers found that there is a group of neurons in the brain called POMC, located in the arcuate nucleus of the brain, which plays a key role in the "dessert stomach" phenomenon. When mice are full and then eat extra sugar, these neurons not only release signal molecules that stimulate satiety, but also release beta-endorphin. This substance can activate the "reward system" in the brain and bring a sense of pleasure, so that mice will continue to consume sugar even if they are full.

The study further found that this "sugar addiction" mechanism is only activated when sugar is consumed, and does not respond to ordinary food or high-fat food. When scientists blocked this neural pathway through experiments, the mice no longer showed interest in additional sugar. Interestingly, this mechanism was activated even before the animals actually ate the sugar. In other words, the mere perception of the presence of sugar is enough to trigger the brain's desire for sweets, and the "dessert stomach" will release beta-endorphin, and the intake of additional sugar will further enhance this release.

To test whether the findings apply to humans, scientists conducted brain scans on volunteers, and the results showed that when the volunteers ingested a sugar solution through a straw, the same area of ​​the brain was activated as in mice. This area is not only associated with satiety, but is also rich in beta-endorphins.

The researchers said that sugar can be quickly absorbed by the body and converted into glycogen and fat for storage. Sugar is scarce in nature, and having an appetite for extra sugar helps animals improve their survival rate and form an evolutionary advantage. But in industrial society, food is abundant and sugar is everywhere. This neural pathway makes it easy for people to consume too much sugar and cause health problems. Based on these new findings, researchers may be able to find more efficient combination therapies to help people deal with health problems such as obesity. (Science and Technology Daily)