The CR400BF-GZ train, the smartest and most frost-resistant Fuxing bullet train model, was deployed in Northeast China's Heilongjiang Province on Monday. It's the coldest and highest region the model has been used in so far. The Fuxing bullet train has a maximum speed of 350 kilometers per hour.

The trains will be operating for the first time during the ongoing 40-day chunyun or the Spring Festival travel rush on routes in China's northernmost alpine region, China Media Group reported.

Compared with other Fuxing models, the CR400BF-GZ has the highest speed level. It is more resistant to low temperature and snow and can operate under an extreme cold environment of -40 C.

The advanced technology represents a major breakthrough for China's high-speed railway technology. The nation's independently developed model can meet the operational demand under various temperature conditions.

The designated system and parts used for constructing the model have all been specifically equipped with low temperature-resistant design, while ensuring smooth ventilation and effectively preventing snow and ice from entering the equipment compartment through the filter.

The train is also more intelligent with advanced technology implemented in targeted fields such as safety monitoring, aiming to further elevate the service quality.

Two sets of the trains will undergo a series of test run, and start operating on lines in Heilongjiang.

The world's first hydrogen-energy urban train with independent intellectual property rights officially rolled off the assembly line in Chengdu, Southwest China's Sichuan Province, on Wednesday. The train adopted the key core technology of the Fuxing bullet train, with a maximum speed of 160 kilometers per hour.

In half a month, two economic powerhouse provinces in East China relaxed their household registration limits, leaving many wondering what the lifting of rule which once restricted migration between rural areas and cities signals for the country? 

Household registration, known as hukou in Chinese, was formed in 1958. It serves to categorize citizens as either rural residents or non-rural residents.

For a long period, almost all large cities have set strict household registration thresholds, the more economically developed, the higher the bar for registering a local hukou. Obtaining a Beijing and Shanghai hukou could be very difficult as the top cities tend to restrict population growth from becoming overcrowded.

Jiangsu Province recently drafted regulations aiming to relax limits for registering a hukou, allowing residents from rural areas to register themselves in cities, except Nanjing and Suzhou.

Earlier, except provincial capital of Hangzhou, Zhejiang Province also announced to ease restrictions.

A VOA report interpreted the policy shift aimed at propping up China's housing market.

Ma Li, former director of China Population and Development Research Center, told the Global Times that the driving force behind allowing new arrivals to become permanent residents in urban areas is aimed at expanding the available urban talent pool to boost local economic development. 

Propping up the housing market is not an explicit goal set by officials, but could be one of those benefits of scrapping household registration limits, Ma noted.

Niu Fengrui, a researcher from Institute of Urban Environment, Chinese Academy of Sciences, told the Global Times that linking the current economic situation to hukou policy reform is too short-sighted, because the essence of lifting household registration curbs is aimed at closing the gap between rural and urban regions and accelerating the urbanization of rural populations, allowing citizens to enjoy equal basic public services, which serves the overall goal of achieving the country's modernization for the wellbeing of all Chinese people. 

Optimizing population distribution

The reform of allowing rural hukou holders to register in urban cities is not a new concept. In 2014, the third meeting of the Central Leading Group for Comprehensively Deepening Reform proposed to facilitate 100 million rural migrants and other residents to resettle into urban areas by 2020.

Previously, Guizhou, Sichuan, Inner Mongolia, Hainan, Guangxi and other jurisdictions have also proposed full opening-up of household registration. At least 18 provinces in China have relaxed restrictions on household registration to date, according to media reports.

However, the policy shift may be less attractive to current residents in rural areas as obtaining a urban hukou leads to a possibility of losing their rural land contracting rights and their rights to use residential land. In well-developed provinces including Zhejiang, the shortened gap between rural and urban regions' living standards means any move to further relax restrictions only delivers marginal benefits, Ma noted. 

But, rural hukou holders who now work and live in urban areas will certainly embrace the change which allows them to move their permanent place of residence to larger cities. It will grant them the equal access with urban citizens to employment, social security, family planning and other social services, Ma said. 

Zhejiang Province said it will increase quotas for public schools and improve capacity for children of residence permit holders to receive education. 

Cai Fang, former vice president of the Chinese Academy of Social Sciences, calculated that the number of migrant workers who live in urban areas but do not hold an urban hukou is likely between 130 million and 170 million. 

But Ma also noted if rural hukou holders convert their registration to an urban area but still are allowed to hold their rural land contracting rights, an urban hukou would become very attractive because of access to better education and employment in cities. "Cities are on the process of optimizing the relevant measures." 

For provincial capital cities including Hangzhou, first-tier cities including Beijing, Shanghai, Shenzhen and Guangzhou where public resources are already stretched, however, the opening up of the household registration policy is unlikely in the short term, experts said. 

According to a recent announcement by China's Ministry of Public Security (MPS) on further relaxing household registration, a points-based household registration system for mega cities with a permanent urban population of over 5 million will also be optimized, encouraging local governments to lift restrictions on annual quotas for local household registration.

"The removal of the household registration system has been discussed for many years in China, I personally believe that the economic and social conditions to scrap the policy are already in place, but the traditional mindset of hukou has slowed down the process of household registration reform." 

The lifting of hukou restrictions will lead to the concentration of populations in urban areas and the decline of rural populations, several demographers noted. 

Following major reform and opening-up, China's urbanization level has increased rapidly, rising from 17.92 percent in 1978 to 64.72 percent in 2021, with the country's urban population reaching 914.25 million, the Guangzhou Daily reported citing Xiao Jincheng, former director of Institute of Land Development and Regional Economy affiliated with the NDRC.

In other words, every year, more than 10 million people move from rural areas to urban areas, find jobs and live in cities. It is believed that China's urbanization level will exceed 70 percent by 2030 and 80 percent by 2050. In the next decade, more than 100 million people will migrate from rural areas to cities and towns, Xiao said.

In the future, as more rural hukou holders move to cities, the country's rural areas are expected to be revitalized as technology-empowered agriculture will nurture professional farmers and ensure talent remains in the farming economy, Ma told the Global Times. "Like those towns in Europe, each town has its own characteristics and own way of development."

Achieving the country's modernization is the process of re-optimizing the layout of China's population, Niu concluded.

Normal is the new strange for the world’s largest cave salamanders.

Biologists are thinking deep thoughts about why some of Europe’s olm salamanders living in darkness have (gasp!) skin coloring and eyes with lenses.

Most salamanders, of course, have skin pigments and grow adult eyes like other vertebrates. But after eons of cave life, olms (Proteus anguinus) have become mostly pinkish-white beasts, about 30 centimeters head to tail, that spend long lifetimes (maybe 70 years) slinking in cold, subterranean water.
Living at 11 to 12° Celsius, olms don’t mature sexually until about age 11 for males and 14 for females. Even then, they never really grow up, staying in water like giant larvae and keeping such youthful features as neck fluff gills into old age. “They look a little creepy, especially if you look at the skull,” says Stanley Sessions of Hartwick College in Oneonta, N.Y. Their blunt heads have no real upper jaw, and their adult eyes start to form but then regress to nubbins buried under skin.
These salamanders live frugally. They can go more than a year without eating. (Lilijana Bizjak Mali of the University of Ljubljana in Slovenia says a lab-dwelling olm survived even after more than 10 years without food.) Females take six-to-12-year breaks between laying eggs, which “develop extraordinarily slowly,” Sessions says. Recently laid olm eggs in Slovenia’s Postojna Cave took about seven weeks to start forming a nervous system; a common spotted salamander takes about one.

Among extreme cave-lifers, the oddballs are the more normal-looking salamanders (for now, called subspecies parkelj), with dark skin and better-developed eyes. For decades, biologists treated these curios as remnants of the most ancient olms that haven’t shed all their daylight ways. But rather than putting the dark salamanders at the base of the genealogical tree of olms, a genetic analysis places them higher among more recent, pale lineages.

“This forces you to consider that the black one probably evolved from white ancestors by reversing cave adaptations,” Sessions says. In evolution, “weirder things have happened.”

Childhood fears are common, normal — Some behavior, such as nail biting, bed-wetting and fearfulness, may actually represent a temporary phase in normal development…. A most important finding [in a recent study] was that the fearful or anxious children, defined … as those with seven or more worries, did not seem to be in any particular psychological trouble.…Anxieties may be part of normal child development. — Science News, June 25, 1966

UPDATE
Actually, there is reason to worry about anxious children. Kids with anxiety disorders, depression or behavioral problems are especially likely to develop a range of difficulties as young adults, say researchers who conducted a long-term study published in 2015. The same goes for kids whose anxiety, mood or behavior issues cause daily problems but don’t qualify as psychiatric ailments. Problems that later dogged the study’s troubled youngsters, who grew up in rural North Carolina, included drug addiction, teenage parenthood, dropping out of high school and criminal arrests.

A mosquito’s spit can be worse than its bite alone. In some cases, the insect’s saliva makes the viral disease dengue fever more severe, a new study finds.

In mice, scientists found that mosquito spit weakened blood vessels, making them more permeable, or “leaky.” Easier exchange between the blood and tissues may help the virus spread faster — and increase the severity of disease — immunologist Michael Schmid and colleagues report online June 16 in PLOS Pathogens.

Dengue virus enters the bloodstreams of nearly 400 million people a year, through the sharp proboscises of tropical Aedes mosquitoes, which also deliver a spit-load of other molecules as they slurp a meal. There are four strains of dengue, which can cause bone and muscle aches, high fever and, in severe cases, death. Overcoming one type of dengue doesn’t protect the host from the other three strains. In fact, subsequent infections are often worse (SN: 6/15/16, p. 22).

Immune cells fight off the first dengue infection, and the body develops antibodies to that strain. But during a subsequent episode with a different variety of dengue, the antibodies from the first infection don’t kill the second — they amplify it. They pull new virus into healthy cells.

Scientists have studied this strange immune trap for three decades, “but what we didn’t know was that saliva could exacerbate it,” says Schmid, now at the University of Leuven in Belgium.
Investigating spit is important, says virologist Eva Harris of the University of California, Berkeley, a coauthor of the study. Molecules in mosquito saliva “can modify and modulate the infection process,” she says. Saliva’s role is well-studied in other viral diseases, like West Nile, but not for dengue.

Schmid’s team inoculated mice either with virus, saliva, or both virus and saliva, during primary and secondary dengue infections. In primary infections, the severity of the disease did not differ substantially between treatments. Symptoms were mild, at most. But in secondary infections, the combination of virus and saliva was lethal to more than half of the mouse population. Without the saliva, mortality was much lower.

To understand why, the researchers ran experiments to track viral spread through the circulatory system. In mouse ears, a molecule about the size of the dengue virus moved farther, and faster, when packaged with mosquito spit. And in the lab, human endothelial cells lining the inner walls of blood vessels sealed less tightly in the presence of Aedes saliva. The researchers also found that mice inoculated with virus alone could be rescued if the skin around the injection site was removed four hours later. The same procedure did not rescue mice dosed with virus and saliva.

These results should be interpreted with caution, says Duane Gubler, an infectious disease researcher at Duke University who was not involved in the study. Various environmental and genetic factors also play a role in the severity of the disease. “It’s not clear-cut,” he says.