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
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.”
For public release at 2 p.m. U.S. Eastern Time (11 a.m. U.S. Pacific Time) on Thursday, Feb. 8, 2024
Foul fumes pose pollinator problems
A team led by researchers at the University of Washington has discovered a major cause for a drop in nighttime pollinator activity — and people are largely to blame.
The researchers found that nitrate radicals (NO3) in the air degrade the scent chemicals released by a common wildflower, drastically reducing the scent-based cues that nighttime pollinators rely on to locate the flower. In the atmosphere, NO3 is produced by chemical reactions among other nitrogen oxides, which are themselves released by the combustion of gas and coal from cars, power plants and other sources. The findings, published Feb. 9 in the journal Science, are the first to show how nighttime pollution creates a chain of chemical reactions that degrades scent cues, leaving flowers undetectable by smell. The researchers also determined that pollution likely has worldwide impacts on pollination.
The team — co-led by Jeff Riffell, a UW professor of biology, and Joel Thornton, a UW professor of atmospheric sciences — studied the pale evening primrose (Oenothera pallida). This wildflower grows in arid environments across the western U.S. They chose this species because its white flowers emit a scent that attracts a diverse group of pollinators, including nocturnal moths, which are one of its most important pollinators.
At field sites in eastern Washington, the researchers collected scent samples from pale evening primrose flowers. Back in the laboratory, they used chemical analysis techniques to identify the dozens of individual chemicals that make up the wildflower’s scent.
“When you smell a rose, you’re smelling a diverse bouquet composed of different types of chemicals,” said Riffell. “The same is true for almost any flower. Each has its own scent made up of a specific chemical recipe.”
Once they had identified the individual chemicals that make up the wildflower’s scent, the team used a more advanced technique called mass spectrometry to observe how each chemical within the scent reacted to NO3. They found that reacting with NO3 nearly eliminated certain scent chemicals. In particular, the pollutant decimated levels of monoterpene scent compounds, which in separate experiments moths found most attractive.
Moths, which smell through their antennae, have a scent-detection ability that is roughly equivalent to dogs — and several thousand times more sensitive than the human sense of smell. Research suggests that several moth species can detect scents from miles away, according to Riffell.
Using a wind tunnel and computer-controlled odor-stimulus system, the team investigated how well two moth species — the white-lined sphinx (Hyles lineata) and the tobacco hawkmoth (Manduca sexta) — could locate and fly toward scents. When the researchers introduced the pale evening primrose’s normal scent, both species would readily fly toward the scent source. But when the researchers introduced the scent and NO3 at levels typical for a nighttime urban setting, Manduca’s accuracy dropped by 50% and Hyles — one of the chief nocturnal pollinators of this flower — could not locate the source at all.
Experiments in a natural setting backed up these findings. In field experiments, the team showed that moths visited a fake flower emitting unaltered scent as often as they visited a real one. But, if they treated the scent first with NO3, moth visitation levels dropped by as much as 70%.
“The NO3 is really reducing a flower’s ‘reach’ — how far its scent can travel and attract a pollinator before it gets broken down and is undetectable,” said Riffell.
The team also compared how daytime and nighttime pollution conditions impacted the wildflower’s scent chemicals. Nighttime pollution had a much more destructive effect on the scent’s chemical makeup than daytime pollution. The researchers believe this is largely due to sunlight degrading NO3.
The team used a computer model that simulates both global weather patterns and atmospheric chemistry to locate areas most likely to have significant problems with plant-pollinator communication. The areas identified include western North America, much of Europe, the Middle East, Central and South Asia, and southern Africa.
“Outside of human activity, some regions accumulate more NO3 because of natural sources, geography and atmospheric circulation,” said Thornton, who added that natural sources of NO3 include wildfires and lightning. “But human activity is producing more NO3 everywhere. We wanted to understand how those two sources — natural and human — combine and where levels could be so high that they could interfere with the ability of pollinators to find flowers.”
The researchers hope their study is just the first of many to help uncover the full scope of pollinator failure.
“Our approach could serve as a roadmap for others to investigate how pollutants impact plant-pollinator interactions, and to really get at the underlying mechanisms,” said Thornton. “You need this kind of holistic approach, especially if you want to understand how widespread the breakdown in plant-pollinator interactions is and what the consequences will be.”
The study highlights the dangers of human-fueled pollution and its implications for all pollinators as well as the future of agriculture.
“Pollution from human activity is altering the chemical composition of critical scent cues, and altering it to such an extent that the pollinators can no longer recognize it and respond to it,” said Riffell.
Approximately three-quarters of the more than 240,000 species of flowering plants rely on pollinators, Riffell said. And more than 70 species of pollinators are endangered or threatened.
Lead author on the paper is Jeremy Chan, a postdoctoral researcher at the University of Copenhagen who conducted this study as a UW doctoral student in biology. Co-authors are Sriram Parasurama in the UW Department of Biology; Rachel Atlas, a postdoctoral researcher at the Pierre Simon Laplace Institute in France who participated in this study as a UW doctoral student in atmospheric sciences; Ursula Jongebloed, a UW doctoral students in atmospheric sciences; Ruochong Xu, a doctoral student at Tsinghua University in China; Becky Alexander, a UW professor of atmospheric sciences; and Joseph Langenhan, a professor of chemistry at Seattle University. The research was funded by the Air Force Office of Scientific Research, the National Science Foundation, the National Institutes of Health, the Human Frontiers in Science Program, and the University of Washington.
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For more information, contact Riffell at 206-348-0789 or jriffell@uw.edu and Thornton at 206-543-4010 or joelt@uw.edu.
Reference: Chan JK, Parasurama S, Atlas R, Xu R, Jongeblood UA, Alexander B, Langenhan JM, Thornton JA, Riffell JA. “Olfaction in the Anthropocene: NO3 negatively affects floral scent and nocturnal pollination.” Science 2024. DOI: 10.1126/science.adi0858
A note from Science for journalists: “Advance copies of embargoed papers may be obtained by registered reporters from our press package, SciPak, at https://www.eurekalert.org/press/scipak/. For reporters having difficulties accessing the paper from the press package, please have them contact scipak@aaas.org.”
Grant numbers:
Air Force Office of Scientific Research: FA9550-21-1-0101 and FA9550-20-1-0422
This photo illustration depicts a tobacco hawkmoth navigating to a flower amid air fouled by vehicle exhaust emissions.
CREDIT
Floris Van Breugel/University of Washington
An innovative approach to shield against foodborne illness
The project, led by University of Missouri researchers, is supported by a $5 million grant from the National Science Foundation’s Convergence Accelerator Program.
COLUMBIA, Mo. — Like a silent saboteur, foodborne pathogens can sneak up and ruin your next meal. One of the biggest culprits is salmonella, a type of bacteria found in many foods that causes more than 1.3 million cases of foodborne illnesses annually according to the Centers for Disease Control and Prevention.
Despite nationwide efforts, salmonella’s infection rates have remained nearly unchanged for the past 30 years. Now, MU is part of an interdisciplinary effort determined to change that after recently receiving a three-year, $5 million grant from the National Science Foundation’s Convergence Accelerator program.
The 19-member team of investigators — with expertise in engineering, poultry and food science, public health and supply chain management — is developing new technology to rapidly detect and mitigate salmonella and other foodborne pathogens throughout the entire poultry supply chain.
Rapid results
One in every 25 packages of chicken found on store shelves is contaminated with salmonella, according to the U.S. Food and Drug Administration. Because chicken is a major source of illnesses from salmonella, the researchers decided to begin their efforts by focusing on helping the poultry industry.
The team’s goal is to significantly reduce the risk of foodborne illness in people, said Mahmoud Almasri, lead principal investigator (PI) and an associate professor of electrical engineering and computer science in the MU College of Engineering.
“Real-time data collected from multiple portable sensors will be added to a transformative sensor-enabled decision support system (SENS-D), allowing us to produce results in one hour or less,” Almasri said. “Our rapid results will enable both the supply chain and health partners to make data-driven decisions to enhance food safety, equity and security by providing evidence-based solutions.”
While the current gold standard of testing for foodborne pathogens takes at least 24 hours to produce results, the researchers’ forward-thinking approach could one day revolutionize the poultry industry and influence policy, said Kate Trout, co-PI and an assistant professor of health sciences in the MU College of Health Sciences.
“These pathogens grow very quicky, so a lot can happen to a food product in just 24 hours,” Trout said. “We think our sensors, combined with our decision support system, could change the way that the entire poultry industry and health stakeholders make decisions to ensure a safer food supply for everyone.”
For instance, this research is vital for helping ensure food safety between the packing plant and a store shelf.
“Our project could help increase the understanding of the impact of time and temperature during distribution and transit,” said Tim Safranski, co-PI and a professor of animal sciences in the MU College of Agriculture, Food and Natural Resources and a state swine extension specialist with MU Extension.
The team will also use advanced statistical and machine learning techniques to improve risk mitigation.
“One strength of our project is using advanced analytics and artificial intelligence (AI) to develop innovative descriptive, predictive and prescriptive capabilities for a safe, efficient, equitable and resilient food supply chain,” said Haitao Li, co-PI and a professor and chair of supply chain and analytics department at the University of Missouri-St. Louis.
While the sensors are currently in protype development, the team is already exploring how the new technology might work for detecting other foodborne pathogens besides salmonella.
"We hope our technology can go beyond poultry and be adapted to detect and reduce the risk of other foodborne pathogens to benefit society as a whole,” said Amit Morey, co-PI and an associate professor of poultry science at Auburn University.
When the technology is ready for real-world use, the team will work with MU Extension to help industry partners in Missouri and beyond understand how to use the new tools through various workforce education and training initiatives.
“We know that just developing a new technology and putting it out in the world doesn’t make a large impact unless we teach people in the industry how to use these new AI and detection technologies,” Trout said. “We’re fortunate to have such a strong state extension program to be able to implement that component of the program.”
The team also includes researchers at University of Notre Dame and Lincoln University.
Since the outbreak of COVID-19, surfaces in public spaces are cleaned more often. While disinfectant solutions eliminate germs, they don’t leave behind a truly bare surface. They deposit a thin film that doesn’t get wiped up, even after giving the surface a good polish. Researchers reporting in ACS ES&T Air show that residues left by commercial cleaning products contain a wider range of compounds that could impact indoor air quality than previously thought.
Residues on indoor surfaces — like those deposited during cooking or cleaning — may contain compounds that are potentially harmful if absorbed through the skin or if they become airborne and are inhaled. To investigate the impact on indoor air quality, scientists study the gunk that builds up with laboratory models of surfaces. In the models, researchers start with the assumption that a thin film exists on any “clean” surface, but the source and actual makeup of these films is unknown. Because the chemical compositions of commercial cleaning products are different from the products used to prep surfaces in the lab, Rachel O’Brien and colleagues hypothesized that commercial sanitizers could be a missing source for the films. So, they decided to characterize films left behind on recently cleaned surfaces.
Using a surface-indoor solvent extractor, the researchers directly collected films from cleaned surfaces in a controlled lab setting and on regularly washed surfaces in university buildings. This method allowed them to pick up and measure a wide array of compounds, including substances that barely evaporate. In contrast, only semivolatile organic compounds (SVOCs) are picked up by wiping a surface film with a solvent-damp cloth, the typical method used to analyze films. The team’s analyses of the residue samples by mass spectrometry found that:
Films from commercial cleaning products were different on the model lab surfaces and university building surfaces and more complex than previously thought.
While the composition of the films was different, they all contained SVOCs that can become airborne and impact indoor air quality.
This method confirmed the presence of lower volatility surfactants, the primary components of soaps, in residues thought to be from the cleaning solutions. However, surfactants’ effects on surface films have not yet been defined.
As a result of these findings, the researchers say that more compounds could be deposited on cleaned surfaces than had previously been identified. They add that future indoor film studies should use surfaces prepared with commercial cleaning products to more accurately identify how the residues impact indoor air quality. And given the extent and regularity of cleaning done in public spaces and people’s homes, more research is needed to determine the effects of lower volatility compounds on film growth and behavior.
The authors acknowledge funding from the Alfred P. Sloan Foundation.
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