The first "ice-free" summer in the Arctic may come early, 10 years earlier than expected丨Tech Weekly

Compiled by Zhou Shuyi

GPT-4's strongest rival: the new generation of AI model Claude 3 released

On March 4, Anthropic, an American artificial intelligence startup, released the AI ​​model Claude 3. Claude 3 is divided into three versions from low to high performance: Haiku, Sonnet, and Opus. In multiple mainstream benchmark evaluations such as MMLU, GPQA, and GSM8K, Opus beat OpenAI's GPT-4 and Google's Gemini.

Source: Anthropic

Claude 3 supports instant chatting with users, automatic text completion, data processing and analysis, and also has visual functions, which can accept visual input such as charts and photos. It is reported that Haiku is the fastest and cheapest model among similar models, and can read a complex paper with charts in 3 seconds (about 10,000 tokens, see the conversion relationship between tokens and characters for details).
https://help.openai.com/en/articles/4936856-what-are-tokens-and-how-to-count-them), the input cost is as low as $0.25 per million tokens, and the output cost is $1.25. The previous Claude model often refused to answer harmless questions due to insufficient context understanding. Claude 3 reduces the probability of false rejection. Claude 3 can also provide more credible answers. Opus is twice as accurate as Claude 2.1 in answering complex open-ended questions. Anthropic said that Claude 3 will soon launch a citation function, indicating the source of the citation in the answer so that users can verify the authenticity of the answer.

Cost and performance of different versions of Claude 3. Note that the horizontal axis is logarithmic. | Source: Anthropic

In addition, the entire Claude 3 series supports context windows of 200,000 tokens (context window, the maximum context space that the model can "consider" at the same time), which is approximately equivalent to 50,000 English words. Anthropic said that Claude 3 can accurately retrieve details in large-scale data, achieving a "near-perfect" recall rate and an accuracy rate of 99%. Claude 3 now provides APIs for 159 countries and regions. Sonnet can experience it for free on the official website claude.ai, while Opus requires a paid subscription at a price of $20 per month. Haiku will launch it later.

Anthropic was founded in 2021 by former OpenAI members Daniela Amodei and Dario Amodei, who was formerly the vice president of research at OpenAI. After OpenAI reached a cooperation with Microsoft in 2019, it gradually moved towards commercialization, and the two left OpenAI due to differences in development concepts.

Microplastics detected in carotid artery plaques increase risk of death by 3.5 times

A study published in NEJM on March 7 found that among more than 200 patients who underwent carotid endarterectomy (surgical removal of atherosclerotic plaques to treat severe stenosis of the extracranial carotid artery), microplastics and nanoplastics were detected in plaque samples of 60% of the patients. These patients subsequently had a significantly increased risk of myocardial infarction, stroke, or all-cause death.

The new study included 304 patients, of whom 257 completed a follow-up of 33.7±6.9 months. The study found that polyethylene was detected in carotid plaque samples from 150 patients (58.4%), with an average level of 21.7±24.5 μg/mg; polyvinyl chloride was detected in samples from 31 patients, with an average level of 5.2±2.4 μg/mg. Compared with patients in whom no microplastics or nanoplastics were detected in their samples, these patients had a 3.53-fold increased risk of myocardial infarction, stroke, or all-cause death during the 34-month follow-up. In addition, patients with higher levels of microplastics in their plaque samples tended to have higher levels of inflammatory markers.

Highly irregularly shaped microplastic particles (arrows) were found inside (left) and outside (right) macrophages in the sample. | Source: NEJM

The researchers said it was unclear why only polyethylene and polyvinyl chloride were detected among the 11 plastic components tested; more work is needed to assess whether these two microplastics accumulate in plaque tissue and whether they are more dangerous than other types of plastics in this regard. They emphasized that the above results cannot prove the causal relationship between microplastics and health risks, and the study did not rule out the influence of confounding factors such as patient health status, behavioral habits, PM2.5 and PM10 exposure levels.

Concerned about microplastics? Try drinking more hot water.

Paper link:
https://doi.org/10.1056%2FNEJMoa2309822

Amphibians can also "feed milk"

Feeding offspring with nutritious milk has always been considered a characteristic of mammals. A study published in Science on March 7 showed that the ringed caecilians (Siphonops annulatus, a caecilian native to Brazil) secrete "milk" rich in lipids and carbohydrates through glands in the walls of the oviduct and "feed" their young several times a day. This is the first time such behavior has been observed in amphibians.

Siphonops annulatus | Source: Carlos Jared

Existing amphibians are divided into three major categories: Anura (such as frogs and toads), Caudata (such as giant salamanders and newts), and the rarest order of Apoda (caecilians). Caecilians, also known as "blind naked snakes", have highly degenerate eyes and are surrounded by constrictions on their bodies, forming many rows of ring folds, resembling worms or snakes. The larvae of the ring-patterned caecilians have highly specialized teeth that can eat the outer layer of their mother's skin to obtain nutrition. However, researchers believe that eating only 1 to 2 times a week is not enough to support the rapid growth of the larvae. Further observations found that in the first few months after the larvae were born, they frequently gathered at the opening of the cloaca at the tail of the mother to ingest the sticky substance secreted by the mother, which is similar to the milk of mammals. In addition, the larvae will promote the mother's lactation through physical contact and high-pitched sounds. Researchers believe that "milk feeding" is a convergent evolutionary phenomenon, and similar behaviors may also exist in other oviparous animals.

Paper link:
https://www.science.org/doi/10.1126/science.ado2094

The first "ice-free" summer in the Arctic may arrive 10 years earlier than predicted

The first "ice-free" day in the Arctic could come more than a decade earlier than previously predicted, and this trend remains unchanged under all greenhouse gas emissions scenarios, a new study shows.

In scientific research, "ice-free" does not mean that there is no ice in the water, but when the sea ice area is less than 1 million square kilometers, the Arctic is considered "ice-free". In recent years, the minimum area of ​​Arctic sea ice occurred in September, about 3.3 million square kilometers.

The study predicts that under all emission scenarios, the Arctic Ocean may become ice-free for the first time in late August or early September between the 2020s and 2030s; by the middle of this century, the Arctic is likely to be ice-free for a whole month in September; by the end of this century, ice-free conditions may last for several months each year, and under high emissions or maintaining current emission rates, the Arctic may even be ice-free in some winter months.

Source: Wikipedia

Researchers believe that greenhouse gas emissions are the main reason for the disappearance of sea ice. The reduction in ice and snow coverage will increase the amount of sunlight absorbed by the ocean, exacerbating ice and snow melting and Arctic warming. The reduction in sea ice will seriously affect Arctic animals such as polar bears that rely on sea ice for survival. In addition, as the ocean warms, non-native fish may enter the Arctic Ocean, and the impact of these invasive species on the local ecosystem is still unclear.

Researchers say that while an ice-free Arctic is inevitable, future emissions levels will still determine how often this happens. Under moderate emissions (current levels), the Arctic may only be ice-free from August to October in late summer and early autumn; but under the highest emissions scenario, by the end of this century, the Arctic may be ice-free for up to nine months a year.

Paper link:
http://dx.doi.org/10.1038/s43017-023-00515-9

The complex relationship between climate change and social unrest in ancient China

"The river is covered with rain and the grass grows tall. The Six Dynasties seem like a dream and birds are singing in the sky." Chinese agricultural civilization emerged in the "Central Plains" about 4,000 years ago. Along the way, it was accompanied by repeated large-scale social unrest, peasant uprisings and nomadic invasions, which formed a unique social structure and national character. Previous studies have proposed the impact of climate change on social unrest, but due to the lack of reliable high-resolution records of dry-wet changes, our understanding of the role of climate change in ancient social unrest is limited.

Based on the carbonate oxygen isotopes of Beilianchi, a small lake on the Loess Plateau in my country, the researchers analyzed the isotopic composition of lake water, inferred the difference between precipitation and evaporation, and reconstructed a high-resolution record of wet-dry changes over the past 5,000 years. The results showed that there were three wet periods and four dry periods in the past 5,000 years; the wet periods were mainly controlled by high precipitation factors, while the dry periods were affected by the synergy of temperature, precipitation and wind speed. This shows that dry periods may occur under different precipitation amplitudes, challenging the traditional perception that arid climates only occur in low precipitation periods.

Using records of dry-wet changes and existing temperature and precipitation records, researchers tried to establish a link between climate change and large-scale social unrest. There were three stages of large-scale social unrest in ancient China - the Spring and Autumn Period and the Warring States Period, the Wei, Jin, Southern and Northern Dynasties, and the Five Dynasties and Ten Kingdoms. The frequency of wars in the northern region mainly occurred during cold and dry periods, indicating that climate deterioration reduced land productivity and accelerated ecological deterioration, which could lead to repeated food shortages and civil wars. In contrast, the relationship between climate and large-scale external aggression is more complicated, and the latter can occur under cold and dry and warm and humid climate conditions. Therefore, the climate background of domestic social unrest and external invasion may not always be consistent.

It is important to note that not all cold and dry periods will lead to large-scale domestic social unrest. Only when social tensions intensify can cold and dry climates play a substantial role in promoting unrest. The researchers said that the new study provides a new perspective and key evidence for exploring the changes in ancient Chinese society, which will help better explore the history and social structure of ancient China and provide value for global climate change research.

Paper link:
https://doi.org/10.1016/j.scib.2023.12.010

The Lancet: The number of obese people in the world has exceeded 1 billion

A survey conducted jointly by the Non-Communicable Disease Risk Factors Collaboration (NCD-RisC) and the World Health Organization (WHO) shows that the total number of obese children, adolescents and adults in the world has exceeded 1 billion, and obesity has become the most common form of nutritional imbalance in most countries.

The researchers analyzed weight and height data of more than 220 million people (63 million of whom were aged 5 to 19 years old and 158 million were aged 20 years and above) from more than 190 countries, and used the body mass index (BMI) to understand the changes in the rates of obesity and underweight in the world's population from 1990 to 2022. For adults, BMI ≥ 30kg/m2 is obese, and BMI < 18.5kg/m2 is underweight; the BMI standard for whether children and adolescents are obese or underweight depends on age and gender.

Data show that from 1990 to 2022, the obesity rate of girls increased from 1.7% to 6.9%, and the obesity rate of boys increased from 2.1% to 9.3%. In 2022, the total number of children and adolescents affected by obesity is close to 160 million (65 million girls and 94 million boys), compared with only 31 million in 1990. In contrast, there were 77 million underweight girls and 108 million boys in 2022, a decrease from 81 million girls and 138 million boys in 1990. The obesity rate of Chinese girls increased from 0.6% to 7.7%, and the obesity rate of boys increased from 1.3% to 15.2%. In 2022, the obesity rate of Chinese girls ranked 102nd in the world, and the obesity rate of boys ranked 70th in the world.

Among adults, the obesity rate for women increased from 8.8% to 18.5%, and for men from 4.8% to 14.0%. In 2022, the total number of adults with obesity is nearly 880 million (504 million women, 374 million men), 4.5 times the number recorded in 1990 (total 195 million, 128 million women, 67 million men). Together with the 159 million obese children in 2022, the total number of people affected by obesity in 2022 exceeds 1 billion. The obesity rate for Chinese women increased from 2.0% to 7.8%, and the obesity rate for men increased from 0.8% to 8.9%. In 2022, the obesity rate for Chinese women ranked 11th from the bottom (190th from the top) and the obesity rate for Chinese men ranked 52nd from the bottom (149th from the top) in the world.

The authors also point out limitations to the study: BMI is not a perfect measure of body fat content and distribution; data from some countries are scarce, leading to higher uncertainty in estimates for those countries. Available data also vary by age group, with less data for those aged 5 to 9 years and those aged 65 years and older, increasing uncertainty in estimates for those age groups.

“This new research underscores the importance of preventing and controlling obesity from early childhood through to adulthood, through appropriate diet, exercise and proper care,” said WHO Director-General Tedros Adhanom Ghebreyesus. “Getting back on track to achieve global obesity targets will require governments and societies working with evidence-based policies from WHO and national public health agencies. Importantly, the private sector needs to work together and must be held accountable for the health impacts of their products.”

Paper link:
https://doi.org/10.1016/S0140-6736(23)02750-2

Large-volume magnetic entropy change at ultralow temperatures

Adiabatic demagnetization refrigeration technology based on the magnetocaloric effect is one of the effective ways to achieve ultra-low temperatures. Since the volume of magnetocaloric materials directly determines the magnetic system and shielding design of the equipment, it is crucial to develop magnetocaloric materials with large volume cooling capabilities. Although increasing the magnetic ion density can enhance the volume refrigeration capacity, it will also lead to stronger magnetic interactions, causing long-range magnetic correlations to appear at higher temperatures. Therefore, there are currently very few materials that can exhibit large volume magnetic entropy changes at ultra-low temperatures (< 1 K).

The researchers proposed a method to achieve large-volume magnetic entropy change at low temperatures by using strongly correlated spin disorder, and verified it in the gadolinium silicate Gd9.33[SiO4]6O2 system. This material has a very high magnetic ion density (1.78 × 1022 cm-3), and even at an extremely low temperature of 50 mK, long-range magnetic order does not appear. These properties enable it to exhibit a huge unit volume magnetocaloric response, which is much higher than the commercial paramagnetic salt refrigeration medium gadolinium gallium garnet (Gd3Ga5O12), and surpasses most reported material systems. The new research provides new ideas for finding and developing ultra-low temperature magnetocaloric materials with higher volume density performance.

Paper link:
https://doi.org/10.1002/advs.202306842

This article is supported by the Science Popularization China Starry Sky Project

Produced by: China Association for Science and Technology Department of Science Popularization

Producer: China Science and Technology Press Co., Ltd., Beijing Zhongke Xinghe Culture Media Co., Ltd.

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