It’s possible that I shall make an ass of myself. But in that case one can always get out of it with a little dialectic. I have, of course, so worded my proposition as to be right either way (K.Marx, Letter to F.Engels on the Indian Mutiny)
Wednesday, October 29, 2025
Ancient tombs reveal the story of Chinese history
Burial site distributions illustrate how people lived and died over thousands of years
Credit: Ma et al., 2025, PLOS One, CC-BY 4.0 (https://creativecommons.org/licenses/by/4.0/)
Tombs scattered across China, built between the 4,000-year old Xia Dynasty and the modern era, reflect the political and social patterns of Chinese history, according to a study published October 29, 2025 in the open-access journal PLOS One by Quanbao Ma from the Beijing University of Civil Engineering and Architecture, China, and colleagues.
The research team mapped the location of ancient tombs in China to search for patterns in their distribution across the country and throughout history. They found that both socioeconomic factors and geography may have influenced where these burial sites are located.
For example, many of the surviving tombs are from periods of Chinese history with relative political and economic stability, such as the Qin-Han and Yuan-Ming-Qing dynasties. Times of war and instability, like the Five Dynasties era, are not as well represented in the archaeological record of tombs. The researchers note that when people’s living standards were high, they could likely spend more time focusing on the afterlife.
Population trends might also have influenced where tombs were built. The researchers note, for example, that war was common in northern China from the late Eastern Han dynasty through the Northern and Southern dynasties. This led people to move southward, and tombs from this era are clustered in these southern locations.
Both the Chengdu-Chongqing and Central Plains regions have a higher number of surviving tombs. The researchers note that Chengdu-Chongqing has relatively flat land and fertile soil, and the Central Plains have flat land and plenty of water, which would have helped ancient settlements develop in these areas. Both areas are also relatively humid, which likely helped preserve artifacts inside the tombs.
Burial sites represent an indispensable source of cultural heritage knowledge, the research team notes — and they hope that this study will help provide some of the scientific foundations needed to preserve these tombs in the future.
The authors add: “This study conducted a systematic digital survey and analysis of the spatiotemporal distribution characteristics and influencing factors of ancient tombs in China, revealing their evolution patterns and influencing factors, thus laying an important theoretical foundation for building a scientific and precise protection system.”
In your coverage, please use this URL to provide access to the freely available article in PLOS One: http://plos.io/4okWzT5
Citation: Ma Q, Li Y, Yang Z, Zhao X, Li C, Shi Z, et al. (2025) The spatiotemporal distribution characteristics and influencing factors of ancient tombs in China: A study on the conservation of ancient tombs in China. PLoS One 20(10): e0333485. https://doi.org/10.1371/journal.pone.0333485
Author countries: China
Funding: This study was supported by the National Social Science Fund of China in the form of a grant awarded to Quanbao Ma (22FYSB019) and the National Social Science Fund of China in the form of a salary for Quanbao Ma. The specific roles of this author are articulated in the ‘author contributions’ section. The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript.
The spatiotemporal distribution characteristics and influencing factors of ancient tombs in China: A study on the conservation of ancient tombs in China
Article Publication Date
29-Oct-2025
1 in 3 university students surveyed from a Parisian suburb report being unable to access desired food, with this food insecurity associated with academic dropout
Credit: Hans, Pixabay, CC0 (https://creativecommons.org/publicdomain/zero/1.0/)
1 in 3 university students surveyed from a Parisian suburb report being unable to access desired food, with this food insecurity associated with academic dropout
Article title: Correlates of food insecurity among university students in a socioeconomically disadvantaged area of the Paris suburbs: A cross-sectional study
If current extinction trends continue, global shark populations will lose much of their variety, thereby threatening ecosystems where specialized species serve vital roles, researchers have found.
In prowling Earth’s oceans for more than 400 million years, sharks have evolved into a delightfully diverse group. As popularly conveyed through children’s books, the famous fish range in size from palm-sized dwarf lanternsharks to school-bus-length whale sharks. Great whites, hammerheads, and many others serve key ecological roles as apex predators at the top of the food chain.
According to previous research, one-third of Earth’s 500 shark species are on the brink of extinction, largely due to human activity. A new Stanford-led analysis reveals the most threatened species tend to have uncommon physiologies and specialized ecological roles – broadly, those living at the ocean’s surface or its deepest depths. Losing these species to extinction would diminish trait diversity until the array of shark body types and habitats dwindles to only medium-sized sharks in a narrow band of mid-ocean depths.
“Our study illustrates that if these major shark extinctions do happen, sharks will become more alike and simplified, and you end up with a more boring world with less diversity of forms,” said lead study author Mohamad Bazzi, a postdoctoral scholar in Earth and planetary sciences at the Stanford Doerr School of Sustainability. “Even small differences between species matter. They each bring something distinct and important.”
As has been documented in other habitats, the loss of trait diversity in key species groups can have far-reaching impacts. For example, a global decline in vulture species is damaging ecosystems, and surging sea urchin populations are putting coral reefs at risk and impacting fisheries.
“This broader erosion of unique shark morphologies would mean that many distinctive features of each species, and the functions that they have in a given ecosystem, would go away,” said senior study author Jonathan Payne, the Dorrell William Kirby Professor and professor of Earth and planetary sciences at the Stanford Doerr School of Sustainability. “Those popular shark books for kids would become a lot less fun and interesting.”
Diminished diversity
For the study, the Stanford researchers consulted the Red List of Threatened Species compiled by the International Union for Conservation of Nature (IUCN), the world’s largest conservation network, to identify a shark genus under notable duress, Carcharhinus. Of the 35 IUCN-recognized Carcharhinus species, 25 are considered either “Vulnerable,” “Endangered,” or “Critically Endangered.” The bull shark and oceanic whitetip shark are two of the biggest, best-known, and at-risk members of this genus.
To search for any non-random patterns of extinction bias, the researchers performed a statistical analysis on the form and structure of more than 1,200 teeth from 30 Carcharhinus present-day species documented in scientific literature. Shark teeth serve as a reliable proxy for a species’ overall size and diet. For instance, tooth sizes generally correlate with body size, while shape and edge features such as serrations can reveal the sharks’ choice of prey.
The researchers found that the more physically and ecologically divergent species tended to also be those at higher risk of extinction. Species in the genus with closer to average sizes, about 3 to 15 feet long, and generalist diets tend to be less threatened than species with more specialized diets and ecological niche-tailored bodies. For example, larger sharks benefit from being hefty by having less risk of predation, but they also must obtain enough food to maintain their bulk.
For Carcharhinus, the findings indicate that if extinctions of some of its member species do occur, the survivors will be more similar than the current group. Bazzi and Payne expect that their findings extend to other shark groups, suggesting that extinction pressure promotes “phenotypic homogenization” – animals’ observable characteristics, such as appearance and behavior, becoming more similar.
Such an outcome would deprive the planet of special and unique creatures, along with potentially useful bio-inspired products.
“With this huge loss of shark traits, humans would be undoing all of this evolutionary work that’s gone on for millions and millions of years,” said Payne. “When we undo all of this work, we’re not only losing things that give us joy, but we’re also losing potential practical evolutionary solutions to problems, such as disease treatments or insights into new materials.”
“We lose in basically every way when we drive species extinct,” Payne added.
Path to positive change
Overall, the findings align with a widely observed pattern that extinctions often reduce trait diversity in a way that favors the survival of “average” generalist organisms over specialists.
The researchers emphasize that the hollowing out of shark diversity predicted by their study, as well as that of other threatened animal groups, can still likely be reversed. Although a confluence of factors endangers shark populations worldwide, including pollution and habitat loss, the single biggest driver – overfishing – can be addressed through more stringent laws, enforcement, and human restraint.
Recent history offers numerous encouraging instances where direct harvesting of an animal group mostly halted, and populations spectacularly rebounded. A prime example: the northern elephant seal, once slaughtered regularly for lamp oil blubber. By the late 1800s, only a single population numbering as few as 20 individuals off Baja California survived. Nowadays, a century after the U.S. and Mexico banned hunting of elephant seals, upward of 150,000 of the seals inhabit West Coast waters, serving their critical role as top predators that regulate overpopulation of prey and help distribute nutrients to promote greater biodiversity and a more resilient ecosystem.
“People don’t need to think about conservation of species as something theoretical, where if we make this change, only our great-great-grandkids might see a different world,” said Payne. “Over the course of just a few decades for some of these threatened sharks, you could already see positive change.”
Extinction Threatens to Cause Morphological and Ecological Homogenization in Sharks
Article Publication Date
29-Oct-2025
A new dimension for spin qubits in diamond
Working in Ania Jayich's lab, newly minted PhD Lillian Hughes is advancing quantum science with two-dimensional arrays of entangled spin qubits in diamond — a breakthrough bringing quantum precision closer to reality.
The path toward realizing practical quantum technologies begins with understanding the fundamental physics that govern quantum behavior — and how those phenomena can be harnessed in real materials. In the lab of Ania Jayich, Bruker Endowed Chair in Science and Engineering, Elings Chair in Quantum Science, and co-director of UC Santa Barbara’s National Science Foundation Quantum Foundry, that material of choice is laboratory-grown diamond.
Working at the intersection of materials science and quantum physics, Jayich and her team explore how engineered defects in diamond — known as spin qubits — can be used for quantum sensing. Among the lab’s standout researchers, Lillian Hughes, who recently earned her Ph.D. and will soon begin postdoctoral work at the California Institute of Technology, has achieved a major advance in this effort.
In a series of three papers co-authored with Jayich — one published in PRX in March and the second and third in Nature in October — Hughes demonstrates, for the first time, how not just individual qubits but two-dimensional ensembles of many defects can be arranged and entangled within diamond. This breakthrough enables the realization of a metrological quantum advantage in the solid state, marking an important step toward the next generation of quantum technologies.
Well-designed defects
“We can create a configuration of nitrogen-vacancy (NV) center spins in the diamonds with control over their density and dimensionality, such that they are densely packed and depth-confined into a 2D layer,” Hughes said. “And because we can design how the defects are oriented, we can engineer them to exhibit non-zero dipolar interactions.” This accomplishment was the subject of the PRX paper, titled “A strongly interacting, two-dimensional, dipolar spin ensemble in (111)-oriented diamond.”
The NV center in diamond consists of a nitrogen atom, which substitutes for a carbon atom, and an adjacent, missing carbon atom (the vacancy).“The NV center defect has a few properties, one of which is a degree of freedom called a spin — a fundamentally quantum mechanical concept. In the case of the NV center, the spin is very long lived,” Jayich said. “These long-lived spin states make NV centers useful for quantum sensing. The spin couples to the magnetic field that we’re trying to sense.”
The ability to use the spin degree of freedom as a sensor has been around since the 1970s’ invention of magnetic resonance imaging (MRI), explained Jayich, noting that the MRI works by manipulating the alignment and energy states of protons and then detecting the signals they emit as they return to equilibrium, creating an image of some part of the internal body.
“Previous quantum-sensing experiments conducted in a solid-state system have all made use of single spins or non-interacting spin ensembles,” Jayich said. “What’s new here is that, because Lillian was able to grow and engineer these very strongly interacting dense spin ensembles, we can actually leverage the collective behavior, which provides an extra quantum advantage, allowing us to use the phenomena of quantum entanglement to get improved signal-to-noise ratios, providing greater sensitivity and making a better measurement possible.”
The type of entanglement-assisted sensing that Hughes’s work enableshas been demonstrated previously in gas-phase atomic systems. “Ideally, for many target applications, your sensor should be easy to integrate and to bring close to the system under study,” Jayich said. “It is much easier to do that with a solid-state material, like diamond, than gas-phase atomic sensors on which, for instance, GPS is based. Furthermore, atomic sensors require significant auxiliary hardware to confine and control, such as vacuum chambers and numerous lasers, making it hard to bring an atomic sensor within nanometer-scale proximity to a protein, for instance, prohibiting high-spatial-resolution imaging.”
In the Jayich lab, the focus is on using diamond sensors to look at material-based electronic effects and phenomena. But, analogous to placing a solid-state sensor into a cell, Jayich said, “You can place material targets into nanometer-scale proximity of a diamond surface, thus bringing them really close to sub-surface NV centers. So it’s very easy to integrate this type of diamond quantum sensor with a variety of interesting target systems. That’s a big reason why this platform is so exciting.”
“A solid-state magnetic sensor of this kind could be very useful for probing, for instance, biological systems,” Jayich said. “Nuclear magnetic resonance [NMR] is based on detecting very small magnetic fields coming from the constituent atoms in, for example, biological systems. Such an approach is also useful if you want to understand new materials, whether electronic materials, superconducting materials, or magnetic materials that could be useful for a variety of applications.”
Squeezing
Any measurement contains associated noise that limits the measurement to some degree of precision. One fundamental source of noise, called quantum projection noise,limits measurement precision to a value called the standard quantum limit, a value that is classically reduced by the square root of N, the number of quantum sensors used in the measurement. If, however, one can engineer a particular form of interactions between the sensors, it becomes possible to break the standard quantum limit for N unentangled sensors. One clever way to do that is to “squeeze” the amplitude of the noise by inducing correlations among the particles and producing a spin-squeezed state.
“It’s as if you were trying to measure something with a meter stick having gradations a centimeter apart; those centimeter-spaced gradations are effectively the amplitude of the noise in your measurement. You would not use such a meter stick to measure the size of an amoeba, which is much smaller than a centimeter,” Jayich said. “By squeezing — silencing the noise — you effectively use quantum mechanical interactions to ‘squish’ that meter stick, effectively creating finer gradations and allowing you to measure smaller things more precisely.”
The second paper describes another type of metrological gain that can be achieved by using the same system, in this case, amplifying the signal strength without increasing the noise level to make a better measurement. In terms of the amoeba example given above, amplifying the signal has the effect of making the amoeba bigger so that the measuring stick with its one-centimeter gradation can now be used to measure it.
In terms of eventual real-world applications, Jayich said, “I don't think the foreseen technical challenges will prevent demonstrating a quantum advantage in a useful sensing experiment in the near future. It’s mostly about making the signal amplification stronger or increasing the amount of squeezing. One way to do that is to control the position of the spins in the 2Dxy plane, forming a regular array.
“There’s a materials challenge here, in that, because we can't dictate exactly where the spins will incorporate, they incorporate in somewhat random fashion within a plane,” Jayich added. “That’s something we’re working on now, so that eventually we can have a grid of these spins, each placed a specific distance from each other. That would address an outstanding challenge to realizing practical quantum advantage in sensing.”
Lillian Hughes, left, and Ania Jayich, right, at the laser confocal microscope which is used interrogate the NV centers after they are formed.
