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)
Saturday, February 10, 2024
Researchers show classical computers can keep up with, and surpass, their quantum counterparts
Researchers adopt innovative method to boost speed and accuracy of traditional computing
Quantum computing has been hailed as a technology that can outperform classical computing in both speed and memory usage, potentially opening the way to making predictions of physical phenomena not previously possible.
Many see quantum computing’s advent as marking a paradigm shift from classical, or conventional, computing. Conventional computers process information in the form of digital bits (0s and 1s), while quantum computers deploy quantum bits (qubits) to store quantum information in values between 0 and 1. Under certain conditions this ability to process and store information in qubits can be used to design quantum algorithms that drastically outperform their classical counterparts. Notably, quantum’s ability to store information in values between 0 and 1 makes it difficult for classical computers to perfectly emulate quantum ones.
However, quantum computers are finicky and have a tendency to lose information. Moreover, even if information loss can be avoided, it is difficult to translate it into classical information—which is necessary to yield a useful computation.
Classical computers suffer from neither of those two problems. Moreover, cleverly devised classical algorithms can further exploit the twin challenges of information loss and translation to mimic a quantum computer with far fewer resources than previously thought—as recently reported in a research paper in the journal PRX Quantum.
The scientists’ results show that classical computing can be reconfigured to perform faster and more accurate calculations than state-of-the-art quantum computers.
This breakthrough was achieved with an algorithm that keeps only part of the information stored in the quantum state—and just enough to be able to accurately compute the final outcome.
“This work shows that there are many potential routes to improving computations, encompassing both classical and quantum approaches,” explains Dries Sels, an assistant professor in New York University’s Department of Physics and one of the paper’s authors. “Moreover, our work highlights how difficult it is to achieve quantum advantage with an error-prone quantum computer.”
In seeking ways to optimize classical computing, Sels and his colleagues at the Simons Foundation focused on a type of tensor network that faithfully represents the interactions between the qubits. Those types of networks have been notoriously hard to deal with, but recent advances in the field now allow these networks to be optimized with tools borrowed from statistical inference.
The authors compare the work of the algorithm to the compression of an image into a JPEG file, which allows large images to be stored using less space by eliminating information with barely perceivable loss in the quality of the image.
“Choosing different structures for the tensor network corresponds to choosing different forms of compression, like different formats for your image,” says the Flatiron Institute’s Joseph Tindall, who led the project. “We are successfully developing tools for working with a wide range of different tensor networks. This work reflects that, and we are confident that we will soon be raising the bar for quantum computing even further.”
The work was supported by the Flatiron Institute and a grant from the Air Force Office of Scientific Research (FA9550-21-1-0236).
Hot water tanks, washing machines, kettles: limescale forms in every domestic appliance that comes into contact with (hot) water – especially in areas where the water is hard, meaning high in calcium. Often the only thing that helps is to use vinegar or a special descaler to dissolve the rock-hard deposits and restore the appliance’s functionality.
This is a nuisance in households – and an expensive problem in thermal power stations, for example those that generate electricity, where the formation of limescale is known as fouling. Heat exchangers are particularly prone to limescale, which greatly reduces the efficiency of the systems: a layer of limescale just one millimetre thick in the heat exchanger’s pipes reduces the efficiency of electricity production by approximately 1.5 percent. To compensate for these losses an additional 8.7 million tonnes of hard coal would have to be burned. That’s bad for the carbon footprint and the climate, and it’s expensive for the electricity producers.
Innovative limescale-repellent surface
A research team from ETH Zurich and the University of California, Berkeley has now found a possible solution to this problem: a special limescale-repellent coating with microscopically small ridges that prevent the adhesion of limescale crystals. The team’s study was recently published in the journal Science Advances.
Fundamental research into the development of limescale-repellent surfaces has been sparse. So the researchers, led by former ETH Professor Thomas Schutzius, took a close look at the interactions among individual growing limescale crystals, the surrounding water flow and the surface at the microscopic level.
Based on this, Schutzius’ doctoral student Julian Schmid and other team members developed several coatings from various soft materials and tested them in the lab at ETH Zurich.
Hydrogel with microstructure is most effective
The most effective coating turned out to be a polymer hydrogel, the surface of which is covered in tiny ridges thanks to microtextured moulds, which the researchers fabricated using photolithography.
The hydrogel’s microstructure is reminiscent of natural models such as shark scales, which also have a ribbed structure to suppress fouling on the sharks’ skin.
In kettles or boilers, the riblets ensure that the limescale crystals have less contact with the surface, meaning they can’t adhere and are thus easier to remove; water flowing over the hydrogel and through the ribbed structure carries them away. While the coating can’t fully prevent limescale crystals from forming, the constant passive removal of the microscopic crystals stops them growing together to form a tenacious layer.
In producing the different coatings, the researchers primarily varied the polymer content. The lower the polymer content and the higher the water content, the less well the calcium carbonate crystals adhere to the surface.
Tests with model particles made of polystyrene show that the coating’s surface structures must be smaller than the particles that are deposited on it. This reduces the contact surface and thus the adhesive force. “We varied the material’s surface structure to achieve the greatest efficiency, then carried out the crystal experiments with this optimum structure size,” Schmid says.
The team’s experiments show that the hydrogel coating is very effective: when water flowed across the hydrogel-coated surface, on which limescale crystals with a size of around 10 micrometres had previously been grown, up to 98 percent of the crystals were removed.
Eco-friendly solution
The researchers emphasise that their solution is more eco-friendly and more efficient than existing approaches to descaling, some of which involve toxic and aggressive chemicals. In contrast, the hydrogel is biocompatible and environmentally friendly. The technology behind this solution should also be scalable: the coating could be applied in various ways that are already in use in industry today.
Rather than applying for a patent for their development, the researchers have deliberately decided in favour of publication in a scientific journal. This means that all interested parties are free to further develop and utilise the new coating.
Schutzius received an ERC Starting Grant for this research in 2019. He no longer works at ETH Zurich, and is now an assistant professor of mechanical engineering at UC Berkeley.
Test set-up with which the researchers tested how lime crystals adhere to different surfaces.
Only a few micrometer-sized lime crystals on the grooved surface under the electron microscope.
Plastic household items and clothing made of synthetic fibers release microplastics: particles less than five millimetres in size that can enter the environment unnoticed. A small proportion of these particles are so small that they are measured in nanometers. Such nanoplastics are the subject of intensive research, as nanoplastic particles can be absorbed into the human body due to their small size – but, as of today, little is known about their potential toxicity.
Empa researchers from Bernd Nowack's group in the Technology and Society laboratory have now joined forces with colleagues from China to take a closer look at nanoparticles released from textiles. Tong Yang, first author of the study, carried out the investigations during his doctorate at Empa. In earlier studies, Empa researchers were already able to demonstrate that both micro- and nanoplastics are released when polyester is washed. A detailed examination of the released nanoparticles released has now shown that not everything that appears to be nanoplastic at first glance actually is nanoplastic.
To a considerable extent, the released particles were in fact not nanoplastics, but clumps of so-called oligomers, i.e. small to medium-sized molecules that represent an intermediate stage between the long-chained polymers and their individual building blocks, the monomers. These molecules are even smaller than nanoplastic particles, and hardly anything is known about their toxicity either. The researchers published their findings in the journal Nature Water.
For the study, the researchers examined twelve different polyester fabrics, including microfiber, satin and jersey. The fabric samples were washed up to four times and the nanoparticles released in the process were analyzed and characterized. Not an easy task, says Bernd Nowack. "Plastic, especially nanoplastics, is everywhere, including on our devices and utensils," says the scientist. "When measuring nanoplastics, we have to take this 'background noise' into account."
Large proportion of soluble particles
The researchers used an ethanol bath to distinguish nanoplastics from clumps of oligomers. Plastic pieces, no matter how small, do not dissolve in ethanol, but aggregations of oligomers do. The result: Around a third to almost 90 percent of the nanoparticles released during washing could be dissolved in ethanol. "This allowed us to show that not everything that looks like nanoplastics at first glance is in fact nanoplastics," says Nowack.
It is not yet clear whether the release of so-called nanoparticulate oligomers during the washing of textiles has negative effects on humans and the environment. "With other plastics, studies have already shown that nanoparticulate oligomers are more toxic than nanoplastics," says Nowack. "This is an indication that this should be investigated more closely." However, the researchers were able to establish that the nature of the textile and the cutting method – scissors or laser – have no major influence on the quantity of particles released.
The mechanism of release has not been clarified yet either – neither for nanoplastics nor for the oligomer particles. The good news is that the amount of particles released decreases significantly with repeated washes. It is conceivable that the oligomer particles are created during the manufacturing of the textile or split off from the fibers through chemical processes during storage. Further studies are also required in this area.
Nowack and his team are focusing on larger particles for the time being: In their next project, they want to investigate which fibers are released during washing of textiles made from renewable raw materials and whether these could be harmful to the environment and health. "Semi-synthetic textiles such as viscose or lyocell are being touted as a replacement for polyester," says Nowack. "But we don't yet know whether they are really better when it comes to releasing fibers.
The nanoparticles on the surface of the fleece fiber are visible under a scanning electron microscope (a). The particles detach during washing (b), so that after four washes there are hardly any left.
PEOPLE WHO VISIT THE ANDES MOUNTAIN RANGE IN SOUTH AMERICA CAN FEEL THE PHYSICAL EFFECTS OF LOWER OXYGEN LEVELS AT HIGHER ALTITUDES. HOWEVER, SOME PEOPLE WHO LIVE THERE HAVE EVOLVED OVER HUNDREDS OF GENERATIONS TO TOLERATE THESE LOW-OXYGEN CONDITIONS.
Humans are still evolving, and Tatum Simonson, PhD, founder and co-director of the Center for Physiological Genomics of Low Oxygen at University of California School of Medicine, plans to use evolution to improve healthcare for all.
Her latest research, which was published February 9, 2024 in Science Advances, reveals that a gene variant in some Andean people is associated with reduced red blood cell count at high altitude, enabling them to safely live high in the mountains in low-oxygen conditions. Simonson’s UC San Diego lab is applying those findings toward understanding whether there may be a genetic component to why some people with sleep apnea or pulmonary diseases such as chronic obstructive pulmonary disease (COPD) fare better than others.
Explained Simonson, “There are people with COPD who breathe a lot and maintain a higher oxygen saturation. Others with the same disease don't breathe as much, and their oxygen saturation is low. Researchers suspect there may be genetic differences underlying this variation, similar to the variation we find in pathways important for oxygen sensing and responses underlying natural selection at high altitude.”
Our cells need oxygen to survive. When there isn’t enough in the environment, our bodies produce extra red blood cells, which transport oxygen throughout the body. Too many red blood cells, however, create a dangerous condition called excessive erythrocytosis (EE), which makes the blood viscous, which could lead to stroke or heart failure.
Her previous research showed that many mountain-dwelling Tibetans exposed to low-oxygen situations are born with innate mechanisms that protect them from poor outcomes at high altitude, including the overproduction of red blood cells. Part of this is due to changes in the regulation of the EPAS1 gene, which lowers hemoglobin concentrations by regulating the pathway that responds to changing oxygen levels. Advances in genetics have shown that modern Tibetans received this genetic advantage from their ancestors who mixed with archaic humans living in Asia tens of thousands of years ago—a unique evolutionary history confined to this population.
For her latest research, Dr. Simonson, who is also the John B. West Endowed Chair in Respiratory Physiology and associate professor in the Division of Pulmonary, Critical Care, Sleep Medicine & Physiology at UC San Diego School of Medicine, zoomed in on the EPAS1 region of the genome. She and her team focused on a mutation in the gene that is present in some people living in the Andes but is absent in all other human populations. When they scanned whole Andean genomes, they found a pattern surrounding this variant suggesting that the genetic change, which alters only a single amino acid in the protein product, happened by chance, relatively recently (from 9,000 to 13,000 years ago), and spread very quickly through hundreds of generations within the Andean population.
Similar to Tibetans, the EPAS1 gene is associated with lower red blood cell count in Andeans who possess it. However, the researchers were surprised to find that the variant works in a completely different way from the Tibetan version of the gene; rather than regulating its levels, the Andean variant changes the genetic makeup of the protein, altering the DNA in every single cell.
“Tibetans have, in general, an average lower hemoglobin concentration, and their physiology deals with low oxygen in a way that doesn’t increase their red blood cells to excessively high levels. Now we have the first signs of evidence that Andeans are also going down that path, involving the same gene, but with a protein-coding change. Evolution has worked in these two populations, on the same gene, but in different ways,” said Simonson.
This study exemplifies a current approach in research that connects genetic targets of natural selection with complex disease genes—understanding, for example, how natural genetic variation contributes to adaptive and maladaptive responses to low oxygen, as this study reveals.
In Simonson’s lab, that means figuring out what downstream target genes are being turned on in response to low oxygen, among other things. Said Simonson, “This paper shows one gene associated with one particular phenotype, but we think there are many different genes and components of oxygen transport involved. It’s just one piece of that puzzle, and could provide researchers with information relevant to other populations.”
Simonson and her team are working with Latino populations in San Diego and El Centro, California, as well as Tijuana and Ensenada, Mexico, taking them to high altitudes and recording their breathing while awake and asleep. They’re cross-referencing their findings with publicly available databases to determine whether the findings they’ve made in Andeans are also found in local Latinos who may share some genetic variants with the Andeans.
“In precision medicine, it’s important to recognize variation in genetic backgrounds, specifically in historically understudied populations,” Simonson said. “If we can find some shared genetic factors in populations in an extreme environment, that may help us understand aspects of health and disease in that group and groups more locally. In that way, this study aims to push research forward, and towards comprehensive personalized medicine approaches in clinics here in San Diego.”
Co-authors of the study include: Elijah S. Lawrence, Wanjun Gu, James J. Yu, Erica C. Heinrich, Katie A. O’Brien, Carlos A. Vasquez, Quinn T. Cowan , Patrick T. Bruck , Kysha Mercader, Mona Alotaibi, Tao Long, James E. Hall, Esteban A. Moya, Marco A. Bauk, Jennifer J. Reeves, Mitchell C. Kong, Rany M. Salem, Keolu P. Fox, Atul Malhotra, Frank L. Powel, Mohit Jain and Alexis C. Komor at UC San Diego, Ryan J. Bohlender, Hao Hu and Chad D. Huff at University of Texas MD Anderson Cancer Center, Cecilia Anza-Ramirez, Gustavo Vizcardo-Galindo , Jose-Luis Macarlupu , Rómulo Figueroa-Mujíca, Daniela Bermudez, Noemi Corante and Francisco C. Villafuerte at Universidad Peruana Cayetano Heredia, Eduardo Gaio at Universidad de Brasília, Veikko Salomaa and Aki S. Havulinna at Finnish Institute for Health and Welfare and Andrew J. Murray at Cambridge University and Gianpiero L. Cavalleri at Royal College of Surgeons in Ireland.
This study was funded, in part, by the National Institutes of Health (Grants R01HL145470 [TSS] and T32HL134632 [JEH]), Geographic Society Explorer Award, and John B West Endowment in Respiratory Physiology (TSS), Wellcome Trust Award 107544/Z/15/Z (FCV), Marie Skłodowska-Curie grant agreement No 890768 (KAO), National Academies of Sciences, Engineering, and Medicine Ford Foundation Fellowship (CAV), National Science Foundation Grant No DGE-2038238 (PTB), Research Corporation for Science Advancement through Cottrell Scholar Award 27502 (ACK), Science Foundation Ireland 12/IP/1727 (GLC), Finnish Foundation for Cardiovascular Research and Juho Vainio Foundation (VS), and Academy of Finland (ASH).
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UC San Diego Researchers found that a gene variant in some Andean people is associated with reduced red blood cell count at high altitude, enabling them to safely live high in the mountains in low-oxygen conditions. The results could help scientists improve precision medicine for sleep apnea and pulmonary diseases, such as chronic obstructive pulmonary disease (COPD).
Alexis Komor is a member of the SAB of Pairwise Plants, is an equity holder for Pairwise Plants and Beam Therapeutics, and receives royalties from Pairwise Plants, Beam Therapeutics, and Editas Medicine via patents licensed from Harvard University. Mohit Jain and Tao Long are affiliated with Sapient Bioanalytics, LLC.
Uncovering the green miracle of urbanization
To reveal the significant changes in vegetation cover in 328 cities in China between 1990 and 2022 and the impact factors
MEC, MEGACITIES; LC, LARGE CITIES; MC, MEDIUM CITIES; SMC, SMALL-MEDIUM CITIES; SM, SMALL CITIES. LETTERS (A, B, C, ETC.) REPRESENT SIGNIFICANT DIFFERENCES AT THE 0.05 LEVEL FOR CITIES OF DIFFERENT SIZES IN EACH YEAR. THE DASHED LINE DENOTES THE MEAN FVC OF CITIES OF ALL SIZES IN EACH YEAR.
Between 1990 and 2005, the national average urban FVC decreased from 0.38 to 0.35 due to the increase of floor area ratio and impervious surface in urban areas. The decline is particularly pronounced in megacities, small, medium and small cities. However, since 2005, this trend has significantly reversed, and all cities in the country have shown an increasing trend of FVC, with an average increase of 27.31% (Figure 1). Especially in megacities, the increase of FVC is particularly significant, which is closely related to the expansion of urban scale and the implementation of ecological construction policies.
Change characteristics of FVC in new and old urban areas. The FVC of new urban areas is generally higher than that of old urban areas, and this phenomenon is particularly obvious in megacities and large cities. This shows that in the process of urban expansion, the planning and construction of new urban areas pay more attention to ecological balance, while the old urban areas are facing the pressure of reducing the green area. Using case studies of Beijing, Yichun, Yulin, Lishui, and Hailaer (Figure 2), the researchers show the changing trend of FVC from the old urban areas to the new urban areas. The data of these cities show that over time, the FVC of new urban areas gradually shifts to high FVC, a trend that is common in cities of different sizes, although the degree of migration to high FVC decreases with the decrease of city size.
The study also found that the average vegetation coverage of all cities in China was positively correlated with urban GDP (R=0.86), temperature (R=0.81), wind speed (R=0.68) and urban construction land area (R=0.70), but negatively correlated with urban precipitation (R=-0.24) (Figure 3). For large and medium-sized cities, the top three factors affecting FVC are GDP, urban population and temperature. However, for cities in arid/semi-arid regions, FVC changes are more sensitive to climatic factors (such as precipitation), indicating that the influence of climatic conditions on urban greening in these regions cannot be ignored.
This study shows the spatial and temporal evolution of urban greening in China, and also reveals the compound effects of economic development, population growth, climate change, and policy orientation on urban vegetation coverage. This is of great significance for guiding future urban planning and promoting urban greening and ecological construction. With the deepening of urbanization process, how to balance urban development and ecological protection to achieve green and sustainable development will become an important issue for city managers and planners.
Publication information
Feng F, Yang X, Jia B, Li X, Li X, Xu C, Wang K. 2024. Variability of urban green space and its driving factors in 328 cities in China. Science China Earth Sciences, 67(02): 466-482, https://doi.org/10.1007/s11430-022-1219-2
Figure 2. Statistical distribution of vegetation coverage in new and old urban areas in different years
Dark green (u2018) indicates the vegetation coverage between urban growth boundaries from 2015 to 2018. By analogy, different colors represent the urban vegetation coverage between the urban boundary of different years and the urban boundary of the previous year. The urban boundary of 1990 is regarded as the most internal urban area (yellow). (a)~(e) show the spatial distribution of vegetation coverage in Beijing, Yichun, Yulin, Lishui and Hailar, respectively. (f) shows the national average FVC of cities of different sizes from the old urban area to the new urban area, where the letters on the bar chart indicate the significant difference in FVC of cities of different sizes at the level of 0.05
In a new study, scientists from the University of Cologne gained new insights into the mechanism of the rhythmic activation of nerve cells (neurons) in stick insects that control the leg muscles during walking. The researchers showed that the neurons that activate the depressor muscle in the leg are rhythmically excited, unlike those of the other leg muscles. So far, it has been assumed that all of these so-called motor neurons are activated in the same way by central neural networks. The study was published under the title ‘The synaptic drive of central pattern-generating networks to leg motor neurons of a walking insect is motor neuron pool specific’ in the journal Current Biology.
The UoC research team investigates the neural foundations of motion generation in animals, in particular those underlying locomotor activities such as walking. For this purpose, the team led by Professor Dr Ansgar Büschges analyses insects, among other arguments, as the requirements for the nervous system regarding the generation and control of walking movements are very similar across animal kingdom. In many animals, for example, there are networks in the central nervous system that form the basis for the generation of rhythmic activity patterns for many forms of movements, whether for rhythmic locomotor activity such as running, swimming, crawling and flying or for vegetative functions such as breathing.
These highly specialized networks are referred to as central pattern generators (CPGs). They generate the rhythmic motor activity of the muscles for movement in interaction with information from sensory organs, neurons called proprioceptors; proprioceptors report movements and inform the central nervous system. In the case of walking, they are located on and in the insect’s legs. The networks do this by activating the so-called motor neurons that innervate the muscles. So far, it was assumed that such CPGs have the same influence on all motor neurons they target. In their new study, Angelina Ruthe, Dr Charalampos Mantziaris and Professor Büschges disproved this assumption about the locomotor activity of insects.
In their experiments, the scientists pharmacologically activated the CPGs in the central nervous system of the stick insect Carausius morosus and investigated their influence on the motor neurons that innervate its leg muscles. They found that all motor neuron groups of the leg muscles, except one, receive identical drive from the networks: rhythmic inhibitory signals from the CPGs. Only the motor neurons, which innervate the depressor muscle of the leg, are controlled by phasic excitatory drive. Interestingly, the leg depressor muscle is precisely the muscle of the insect which is responsible for generating leg stance during any walking situation – regardless of whether the animal runs up or down horizontally, on the ceiling or on a branch. “The rhythmic excitation and thus the specific activation of this motor neuron pool by the CPGs could serve to ensure the exact timing of the contraction of the depressor muscle and thus the start of the stance phase and its stabilization," explained Professor Büschges.
The study was funded by the German Research Foundation (DFG).
GENDER-BASED HEAT MAP IMAGES SHOW WHERE MEN TEND TO LOOK AND WHERE WOMEN TEND TO LOOK ON A PATH AT NIGHT. WOMEN FOCUSED SIGNIFICANTLY MORE ON POTENTIAL SAFETY HAZARDS — THE PERIPHERY OF THE IMAGES — WHILE MEN LOOKED DIRECTLY AT FOCAL POINTS OR THEIR INTENDED DESTINATION
CREDIT: IMAGES COURTESY OF THE JOURNAL OF VIOLENCE AND GENDER.
An eye-catching new study shows just how different the experience of walking home at night is for women versus men.
The study, led by Brigham Young University public health professor Robbie Chaney, provides clear visual evidence of the constant environmental scanning women conduct as they walk in the dark, a safety consideration the study shows is unique to their experience.
Chaney and co-authors Alyssa Baer and Ida Tovar showed pictures of campus areas at four Utah universities — Utah Valley University, Westminster, Brigham Young University and University of Utah — to participants and asked them to click on areas in the photos that caught their attention. Women focused significantly more on potential safety hazards — the periphery of the images — while men looked directly at focal points or their intended destination.
“The resulting heat maps represent perhaps what people are thinking or feeling or doing as they are moving through these spaces,” Chaney said. “Before we started the study, we expected to see some differences, but we didn’t expect to see them so contrasting. It’s really visually striking.”
Nearly 600 individuals took part in the study, published recently in the journal Violence and Gender, with 56% of participants being female and 44% being male. Each participant looked at 16 images and were told to imagine themselves walking through those areas. They used a Qualtrics heat map tool to click on the areas of the image that stood out the most to them.
While men tended to focus on the path or a fixed object (like a light, the walking path or a garbage can), the women's visual pattern represented a scanning of the perimeter (bushes, dark areas next to a path).
Chaney, along with Baer and Tovar — both BYU undergrads at the time of the study’s inception — say the findings provide some insight into what it is like to walk home as a woman, which could be multiplied through years or a lifetime of experiences.
“This project has been a fantastic conversation starter to bring awareness to lived experiences, particularly of women in this case,” said Baer, who recently finished graduate school at George Washington University and now works in Washington, D.C. “My hope is that in having concrete data we are able to start conversations that lead to meaningful action.”
Authors said the data suggests that because environment is perceived and experienced differently by women and men, decision makers in building campus and community environments should consider the varied experiences, perceptions and safety of both.
“Why can’t we live in a world where women don’t have to think about these things? It’s heartbreaking to hear of things women close to me have dealt with,” Chaney said. “It would be nice to work towards a world where there is no difference between the heat maps in these sets of images. That is the hope of the public health discipline.”
