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)
Thursday, June 02, 2022
Widespread futile care could contribute to veterinary burnout
ITHACA, N.Y. – More than 99% of veterinarians surveyed said they’d encountered useless or non-beneficial veterinary care in their careers, according to a new Cornell-led study that documents the prevalence of futile care for the first time. The authors use a working definition of futile care as continuing treatment when relevant goals can no longer be reached.
“Before Cornell, I was in private practice in Los Angeles for 11 years. When faced with a dilemma like this, I had an obligation to advocate for what I thought was in the best interest of the pet,” said Dr. Nathan Peterson, associate clinical professor with the section of emergency and critical care and lead author of the study.
“But I also had an obligation to the owner,” Peterson said. “I couldn’t just do what I thought was right. It’s really quite distressing for the veterinarian and for the technicians and nurses who have to carry out the care.”
The study, co-authored by researchers at Harvard Medical School’s Center for Bioethics, also found that 89% of veterinarians said they had administered futile care, and 42% said it occurs frequently, more than six times per year.
The owner-centered approach, the authors write, can exacerbate moral distress for veterinarians and care teams. Previous research by co-authors showed that futile veterinary care was responsible for frequent and severe moral distress in the veterinary community, which they said occurs when a clinician believes they know the right thing to do but are prevented from doing it.
“We’re in the midst of a mental health crisis in our profession, and we’re very interested in whether futile care contributes to that, which I suspect it does,” Peterson said. “We felt that a first step is documenting that it happens. My hope for the research is that it opens conversations around futile care, and hopefully professional organizations can take a leadership role and try to provide some guidance for how to resolve these conflicts.”
The authors suggest establishing a definition for futile care in the profession – respondents were not in total consensus about what futile care means – as well as guidance around how decisions for care are made.
“I think as a profession we have focused for so long on alleviating suffering by continuing treatment and making animals healthier,” Peterson said. “And we’re not as prepared to strongly advocate for euthanasia, to have those conversations, even when we think that’s the best way to alleviate suffering.”
In future research, Peterson hopes to investigate the impact of futile care on support staff. “That feeling of powerlessness for the veterinarian is certainly magnified for the technicians who are often not involved in the decisions and who are directly responsible for providing care,” he said.
New research led by scientists at the Milner Centre for Evolution at the University of Bath suggests that determining evolutionary trees of organisms by comparing anatomy rather than gene sequences is misleading. The study, published in Communications Biology, shows that we often need to overturn centuries of scholarly work that classified living things according to how they look.
Since Darwin and his contemporaries in the 19th Century, biologists have been trying to reconstruct the “family trees” of animals by carefully examining differences in their anatomy and structure (morphology).
However, with the development of rapid genetic sequencing techniques, biologists are now able to use genetic (molecular) data to help piece together evolutionary relationships for species very quickly and cheaply, often proving that organisms we once thought were closely related actually belong in completely different branches of the tree.
For the first time, scientists at Bath compared evolutionary trees based on morphology with those based on molecular data, and mapped them according to geographical location.
They found that the animals grouped together by molecular trees lived more closely together geographically than the animals grouped using the morphological trees.
Matthew Wills, Professor of Evolutionary Paleobiology at the Milner Centre for Evolution at the University of Bath, said: “It turns out that we’ve got lots of our evolutionary trees wrong.
“For over a hundred years, we’ve been classifying organisms according to how they look and are put together anatomically, but molecular data often tells us a rather different story.
“Our study proves statistically that if you build an evolutionary tree of animals based on their molecular data, it often fits much better with their geographical distribution.
“Where things live – their biogeography – is an important source of evolutionary evidence that was familiar to Darwin and his contemporaries.
“For example, tiny elephant shrews, aardvarks, elephants, golden moles and swimming manatees have all come from the same big branch of mammal evolution - despite the fact that they look completely different from one another (and live in very different ways).
“Molecular trees have put them all together in a group called Afrotheria, so-called because they all come from the African continent, so the group matches the biogeography.”
The study found that convergent evolution – when a characteristic evolves separately in two genetically unrelated groups of organisms – is much more common than biologists previously thought.
Professor Wills said: “We already have lots of famous examples of convergent evolution, such as flight evolving separately in birds, bats and insects, or complex camera eyes evolving separately in squid and humans.
“But now with molecular data, we can see that convergent evolution happens all the time – things we thought were closely related often turn out to be far apart on the tree of life.
“People who make a living as lookalikes aren’t usually related to the celebrity they’re impersonating, and individuals within a family don’t always look similar - it’s the same with evolutionary trees too.
“It proves that evolution just keeps on re-inventing things, coming up with a similar solution each time the problem is encountered in a different branch of the evolutionary tree.
“It means that convergent evolution has been fooling us - even the cleverest evolutionary biologists and anatomists - for over 100 years!”
Dr Jack Oyston, Research Associate and first author of the paper, said: “The idea that biogeography can reflect evolutionary history was a large part of what prompted Darwin to develop his theory of evolution through natural selection, so it's pretty surprising that it hadn't really been considered directly as a way of testing the accuracy of evolutionary trees in this way before now.
“What's most exciting is that we find strong statistical proof of molecular trees fitting better not just in groups like Afrotheria, but across the tree of life in birds, reptiles, insects and plants too.
“It being such a widespread pattern makes it much more potentially useful as a general test of different evolutionary trees, but it also shows just how pervasive convergent evolution has been when it comes to misleading us.”
IMAGE: TIME SEQUENCE SHOWING DETAILS OF A CORK EXPELLED FROM A CHAMPAGNE BOTTLENECK STORED AT 20 DEGREES CELSIUS CAPTURED THROUGH HIGH-SPEED IMAGING.view more
CREDIT: GÉRARD LIGER-BELAIR
WASHINGTON, June 1, 2022 – Opening a bottle of champagne traditionally marks the beginning of a festive celebration. Following the fun pop of the cork, a fizz of bubbles releases into the air, and finally, there is the pleasant tingle on the tongue.
But there is much more that comes out of the pop than meets the senses, according to researchers in France and India. In Physics of Fluids, by AIP Publishing, computational fluid dynamics simulations revealed the formation, evolution, and dissipation of shock wave patterns as the carbon dioxide mixture shoots through the bottleneck in the first millisecond after cork popping.
The findings could provide insight into the complex and transient behavior of supersonic flow in applications ranging from rocket launchers, ballistic missiles, and wind turbines to electronics manufacturing and underwater vehicles. The simulations build on experimental research in 2019 that showed, for the first time, the formation of shock waves during cork popping.
"We wanted to better characterize the unexpected phenomenon of a supersonic flow that takes place during champagne bottle uncorking," said co-author Robert Georges, from the Université de Rennes 1. "We hope our simulations will offer some interesting leads to researchers, and they might consider the typical bottle of champagne as a mini-laboratory."
In the initial uncorking phase, the gas mixture is partially blocked by the cork, preventing the ejecting champagne from reaching the speed of sound. But as the cork further releases, the gas mixture escapes radially at supersonic speed, balancing its pressure through a succession of normal and oblique shock waves.
The waves combine to form shock diamonds, patterns of rings typically seen in rocket exhaust plumes. The bottle symmetry leads to a crown-shaped supersonic expansion. Eventually, the pressure becomes too low to maintain an appropriate nozzle pressure ratio for supersonic speed at the bottleneck and cork's edge.
"Our paper unravels the unexpected and beautiful flow patterns that are hidden right under our nose each time a bottle of bubbly is uncorked," said co-author Gérard Liger-Belair, from Université de Reims Champagne-Ardenne. "Who could have imagined the complex and aesthetic phenomena hidden behind such a common situation experienced by any one of us?"
The researchers plan to explore other parameters, such as temperature, volume, and bottleneck diameter, along with the physicochemical processes that accompany champagne bottle uncorking. For instance, they are interested in how supersonic flow is affected by ice particle formation caused by the drastic temperature drop as the fizz ejects from the bottle.
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The article "Computational Fluid Dynamic simulation of the supersonic CO2 flow during champagne cork popping" is authored by Abdessamad Benidar, Robert Georges, Vinayak Kulkarni, Daniel Cordier, and Gérard Liger-Belair. The article appears in Physics of Fluids (DOI: 10.1063/5.0089774 and can be accessed at https://aip.scitation.org/doi/full/10.1063/5.0089774.
ABOUT THE JOURNAL
Physics of Fluids is devoted to the publication of original theoretical, computational, and experimental contributions to the dynamics of gases, liquids, and complex fluids. See https://aip.scitation.org/journal/phf.
NIH/NATIONAL INSTITUTE OF ALLERGY AND INFECTIOUS DISEASES
IMAGE: TRANSMISSION ELECTRON MICROSCOPE IMAGE OF SARS-COV-2 VIRUS PARTICLES EMERGING FROM THE SURFACE OF A CELL CULTURED IN THE LAB. IMAGE CAPTURED AND COLORIZED AT ROCKY MOUNTAIN LABORATORIES IN HAMILTON, MONTANA.view more
CREDIT: NIAID
A National Institutes of Health-funded study has found that people with food allergies are less likely to become infected with SARS-CoV-2, the virus that causes COVID-19, than people without them. In addition, while previous research identified obesity as a risk factor for severe COVID-19, the new study has identified obesity and high body mass index (BMI) as associated with increased risk for SARS-CoV-2 infection. In contrast, the study determined that asthma does not increase risk for SARS-CoV-2 infection.
The Human Epidemiology and Response to SARS-CoV-2 (HEROS) study also found that children ages 12 years or younger are just as likely to become infected with the virus as teenagers and adults, but 75% of infections in children are asymptomatic. In addition, the study confirmed that SARS-CoV-2 transmission within households with children is high. These findings were published today in the Journal of Allergy and Clinical Immunology.
“The HEROS study findings underscore the importance of vaccinating children and implementing other public health measures to prevent them from becoming infected with SARS-CoV-2, thus protecting both children and vulnerable members of their household from the virus,” said Anthony S. Fauci, M.D., director of the National Institute of Allergy, and Infectious Diseases (NIAID), part of NIH. “Furthermore, the observed association between food allergy and the risk of infection with SARS-CoV-2, as well as between body-mass index and this risk, merit further investigation.” NIAID sponsored and funded the HEROS study.
Tina V. Hartert, M.D., M.P.H, co-led the research with Max A. Seibold, Ph.D. Dr. Hartert is director of the Center for Asthma and Environmental Sciences Research, vice president for translational science, the Lulu H. Owen Chair in Medicine, and a professor of medicine and pediatrics at the Vanderbilt University School of Medicine in Nashville. Dr. Seibold is director of computational biology, the Wohlberg and Lambert Endowed Chair of Pharmacogenomics, and a professor of pediatrics in the Center for Genes, Environment, and Health at National Jewish Health in Denver.
The HEROS study team monitored for SARS-CoV-2 infection in more than 4,000 people in nearly 1,400 households that included at least one person age 21 years or younger. This surveillance took place in 12 U.S. cities between May 2020 and February 2021, before the widespread rollout of COVID-19 vaccines among non-healthcare workers in the United States and before the widespread emergence of variants of concern. Participants were recruited from existing, NIH-funded studies focused on allergic diseases. Roughly half of the participating children, teenagers and adults had self-reported food allergy, asthma, eczema, or allergic rhinitis.
A caregiver in each household took nasal swabs of participants every two weeks to test for SARS-CoV-2 and filled out weekly surveys. If a member of the household developed symptoms consistent with COVID-19, additional nasal swabs were taken. Blood samples also were collected periodically and after a family’s first reported illness, if there was one.
When the HEROS study began, preliminary evidence from other research suggested that having an allergic disease might reduce a person’s susceptibility to SARS-CoV-2 infection. The HEROS investigators found that having self-reported, physician-diagnosed food allergy cut the risk of infection in half, but asthma and the other allergic conditions monitored—eczema and allergic rhinitis—were not associated with reduced infection risk. However, the participants who reported having food allergy were allergic to three times as many allergens as the participants who did not report having food allergy.
Since all these conditions were self-reported, the HEROS study team analyzed the levels of immunoglobulin E (IgE)-specific antibodies, which play a key role in allergic disease, in blood collected from a subset of participants. A correspondence between self-reported food allergy and food allergen-specific IgE measurements supports the accuracy of self-reported food allergy among HEROS participants, according to the investigators.
Dr. Hartert and colleagues speculate that type 2 inflammation, a characteristic of allergic conditions, may reduce levels of a protein called the ACE2 receptor on the surface of airway cells. SARS-CoV-2 uses this receptor to enter cells, so its scarcity could limit the virus’s ability to infect them. Differences in risk behaviors among people with food allergy, such as eating out at restaurants less often, also could explain the lower infection risk for this group. However, through biweekly assessments, the study team found that households with food-allergic participants had only slightly lower levels of community exposure than other households.
Previous studies have shown that obesity is a risk factor for severe COVID-19. In the HEROS study, investigators found a strong, linear relationship between BMI―a measure of body fat based on height and weight―and the risk of SARS-CoV-2 infection. Every 10-point increase in BMI percentile raised the risk of infection by 9%. Participants who were overweight or obese had a 41% greater risk of infection than those who were not. More research is needed to explain these findings. In this regard, planned analyses of gene expression in cells collected from nasal swabs of participants before and after SARS-CoV-2 infection may provide clues about the inflammatory environment associated with infection, which may change as BMI increases, according to the investigators.
The HEROS researchers found that children, teenagers and adults in the study all had around a 14% chance of SARS-CoV-2 infection during the six-month surveillance period. Infections were asymptomatic in 75% of children, 59% of teenagers and 38% of adults. In 58% of participating households where one person became infected, SARS-CoV-2 was transmitted to multiple household members.
The amount of SARS-CoV-2 found in nasal swabs, that is, the viral load, varied widely among study participants in all age groups. The viral load range among infected children was comparable to that of teenagers and adults. Given the rate of asymptomatic infection in children, a larger proportion of infected children with high viral loads may be asymptomatic compared to infected adults with high viral loads.
The HEROS investigators concluded that young children may be very efficient SARS-CoV-2 transmitters within the household due to their high rate of asymptomatic infection, their potentially high viral loads, and their close physical interactions with family members.
Reference: MA Seibold et al. Risk factors for SARS-CoV-2 infection and transmission in households with asthmatic and allergic children. A prospective surveillance study. Journal of Allergy and Clinical Immunology DOI: 10.1016/j.jaci.2022.05.014 (2022).
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About the National Institutes of Health (NIH): NIH, the nation's medical research agency, includes 27 Institutes and Centers and is a component of the U.S. Department of Health and Human Services. NIH is the primary federal agency conducting and supporting basic, clinical, and translational medical research, and is investigating the causes, treatments, and cures for both common and rare diseases. For more information about NIH and its programs, visit https://www.nih.gov/.
One suggested way to save humankind in the event of a deadly pandemic or other extreme global catastrophe is establishing a safe refuge – on an island or in such far-out places as the moon or under water -- where a portion of the human population can stay alive.
A new paper published in the journal Risk Analysis suggests that the COVID-19 pandemic demonstrates that a refuge is a viable concept and may not need to be geographically isolated or in an exotic location. In their analysis, the authors explore how and why both China and Western Australia served as successful refuges during the first two years of the pandemic.
Seth Baum, a geographer and executive director of the Global Catastrophic Risk Institute in Washington, D.C., and Vanessa Adams, a geographer at the University of Tasmania, conducted a case study of China and Western Australia, both political jurisdictions that share their borders with others yet managed to keep COVID-19 infections low. From March 2020 to January 2022, China’s estimated cases per 100,000 people were 1,358 compared to 98,556 in the United States and 142,365 in India. Western Australia’s official cases were 48.8.
Previous research has shown that island nations like Iceland, Australia, and New Zealand are good candidates for a refuge -- based on their success in keeping COVID-19 infections low in the first nine months of the pandemic. (A pandemic refuge is a place with low medical risk where a pathogen has not spread significantly.) The new study, covering nearly two years of the pandemic, suggests that geographic isolation (or being on an island) is not a prerequisite for a pandemic refuge. “China is a very clear case in point,” says Baum. “It has succeeded despite having the world’s longest land border.”
In their paper, Baum and Adams examine both the differences and similarities between China and Western Australia. China is authoritarian, collectivist, and heavily populated in the most populous region of the world. Western Australia is democratic, individualist, and sparsely populated in one of the most remote regions of the world.
Yet the two jurisdictions are similar in other, important ways. Both have a high degree of centralization and a high capacity for self-isolation -- China via its authoritarian government, Western Australia via its social isolation and strong economy driven by a booming mining industry. Both also have strong in-group cohesion and have been highly motivated to avoid pathogen spread. Both China and Western Australia have also maintained extensive trade with outside places throughout the pandemic.
“This is encouraging because it suggests that pandemic refuges can provide a high degree of economic support for outside populations during pandemics, an important element for achieving the global objective of refuges – the continuity of civilization,” says Baum.
“Pandemic refuges are a risk management policy concept worthy of serious consideration,” adds Adams, “alongside other public health measures such as vaccines and physical distancing.”
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About SRA
The Society for Risk Analysis is a multidisciplinary, interdisciplinary, scholarly, international society that provides an open forum for all those interested in risk analysis. SRA was established in 1980 and has published Risk Analysis: An International Journal, the leading scholarly
India’s relic forests reveal a new species of leopard gecko
VIDEO: PAINTED LEOPARD GECKO ( EUBLEPHARIS PICTUS)view more
CREDIT: SANJAY KUMAR & AVINASH CH.
Deep in the forests of Odisha and Andhra Pradesh in India lives a colourful gecko species that only now revealed its true identity. Meet Eublepharis pictus, also known as the Painted Leopard Gecko.
In 2017, researchers Zeeshan A. Mirza of theNational Centre for Biological Sciences in Bangalore and C. Gnaneswar of theMadras Crocodile Bank Trust in Chennai found a gecko in a water tank near a temple in Vishakhapatnam, Andhra Pradesh, during a field survey. Back then, they identified it as belonging to the East Indian Leopard Gecko species (Eublepharis hardwickii).
“The species appears to be common in the hill forests, but its distinctness was only confirmed by other researchers,” Zeeshan Mirza explains.
In a phylogenetic study, where they looked for the evolutionary history and relationships within and between the leopard gecko species in the genus Eublepharis, the researchers found that what had until then been considered a southern population of East Indian Leopard Geckomight be distinct enough to represent a new species.
Once they had molecular data they could work with, the team made morphological comparisons between the species, looking at specimens across natural history museums.
“These lizards have conserved morphologies and most species are quite similar in general appearance,” Zeeshan Mirza elaborates. “With a few characters based on the number of specimens examined, we described the species and named it the Painted Leopard Gecko – in Latin, Eublepharis pictus, for its colouration.” Theypublished their discovery in the open-access scientific journalEvolutionary Systematics.
With this new addition, the gecko genus Eublepharis now contains 7 species. Two of them - E. pictus and E. satpuraensis - were described by Zeeshan Mirza.
The Painted Leopard Gecko measures 11.7 cm in length, which is somewhat large for a leopard gecko. The Brahmani River, which runs through the Eastern Ghats, separates it geographically from the East Indian Leopard Gecko, with which it shares a lot of similar traits.
The new species lives in dry evergreen forests mixed with scrub and meadows. It is strictly nocturnal, actively foraging along trails in the forest after dusk. While looking for food, it has been observed licking surfaces as it moves, which suggests it might use its tongue as a sensory organ.
Even though the Painted Leopard Gecko seems to be widespread across the state of Odisha and northern Andhra Pradesh, the researchers worry about its conservation. “The species is collected for the pet trade and even now may be smuggled illegally,” they write in their paper, which is why they refrain from giving out the exact locations where it may be found.
The authors believe the species would stand more of a chance against humans if more people knew it was actually harmless. To protect it, they suggest listing it as Near Threatened based on IUCN conservation prioritisation criteria, until more is known about the size of its populations.
Further research may also encourage better protection of biodiversity in the area. “The Eastern Ghats are severely under-surveyed, and dedicated efforts will help recognize it as a biodiversity hotspot,” the authors conclude.
Original source:
Mirza ZA, Gnaneswar C (2022) Description of a new species of leopard geckos, Eublepharis Gray, 1827 from Eastern Ghats, India with notes on Eublepharis hardwickii Gray, 1827. Evolutionary Systematics 6(1): 77-88.https://doi.org/10.3897/evolsyst.6.83290
image: The rate of deadly drug overdoses among Black people in Kentucky more than doubled from 2016 to 2020, according to a new analysis by University of Kentucky researchers.view more
Credit: Darwin Brandis, iStock / Getty Images Plus
LEXINGTON, Ky. (June 1, 2022) — The rate of deadly drug overdoses among Black people in Kentucky more than doubled from 2016 to 2020, according to a new analysis by University of Kentucky researchers.
The Black overdose mortality rate increased by nearly 117% — from 21.2 deaths for every 100,000 people in 2016 to 46.0 per 100,000 in 2020, according to the research published in the journal Public Health Reports.
Using Kentucky death certificates and postmortem toxicology reports from 2016-2020, the team of researchers who are part of UK’s HEALing Communities Study (HCS) evaluated changes in drug overdose mortality for various racial and ethnic groups. The study shows that about 80% of drug overdose deaths among all racial and ethnic groups in Kentucky involved opioids.
“Historically, opioid overdose death rates have been disproportionately higher among white individuals, but the new study shows that the rates for both white and Black individuals in Kentucky are now nearly the same,” said study co-author Svetla Slavova, Ph.D., associate professor in the UK College of Public Health who is a part of the HCS research team and a faculty member in the Kentucky Injury Prevention and Research Center. “This reflects national data, which show that disparities in opioid overdose deaths continue to worsen for Black people.”
The shifting demographics are helping to inform drug overdose prevention efforts in Kentucky, including UK’s HCS aimed at reducing opioid-involved overdose deaths in 16 intervention communities across the Commonwealth.
“Black Kentuckians who are at risk for drug overdose may face additional barriers to accessing treatment,” said Sharon Walsh, Ph.D., the principal investigator for UK's HCS and director of UK’s Center on Drug and Alcohol Research. “This study underscores the importance of our efforts to expand treatment and harm reduction services in Kentucky’s communities of color.”
HCS has been expanding efforts to reach and engage people in communities of color through culturally tailored interventions and partnerships with community organizations. The goal is to connect people to evidence-based practices proven to reduce opioid overdose, including increasing access to and treatment with FDA-approved medications for opioid use disorder (including buprenorphine and methadone), overdose education and distribution of naloxone, a life-saving medication that rapidly reverses an opioid overdose.
The study reflects other national trends, including a rise in overdose deaths driven by illegally manufactured fentanyl. Fentanyl was identified as a contributing substance in more than 70% of drug overdose deaths among all ethnicities in Kentucky in 2020.
While fentanyl is linked to most overdose deaths, the study reports a rise in the involvement of stimulants, such as methamphetamines and cocaine. From 2016 to 2020, the number of psychostimulant-involved drug overdose deaths increased 513% among Black individuals and 191% among whites.
The study authors note that more research is needed to fully understand the social, cultural and illicit market circumstances driving these rapid trend changes as well as drivers of health inequity that may be contributing to drug overdose deaths among various racial and ethnic groups.
Research reported in this publication was supported by funding from the Centers for Disease Control and Prevention under Award Number 5 NU17CE924971-03, by the U.S. Food and Drug Administration under Award Number HHSF223201810183C under Broad Agency Announcement Number 17-00123, and by the National Institutes of Health through the Helping to End Addiction Long-term Initiative under Award Number UM1DA049406. The content is solely the responsibility of the authors and does not necessarily represent the official views of the Centers for Disease Control and Prevention, U.S. Food and Drug Administration or the National Institutes of Health.
The University of Kentucky is increasingly the first choice for students, faculty and staff to pursue their passions and their professional goals. In the last two years, Forbes has named UK among the best employers for diversity, and INSIGHT into Diversity recognized us as a Diversity Champion four years running. UK is ranked among the top 30 campuses in the nation for LGBTQ* inclusion and safety. UK has been judged a “Great College to Work for" three years in a row, and UK is among only 22 universities in the country on Forbes' list of "America's Best Employers." We are ranked among the top 10 percent of public institutions for research expenditures — a tangible symbol of our breadth and depth as a university focused on discovery that changes lives and communities. And our patients know and appreciate the fact that UK HealthCare has been named the state’s top hospital for five straight years. Accolades and honors are great. But they are more important for what they represent: the idea that creating a community of belonging and commitment to excellence is how we honor our mission to be not simply the University of Kentucky, but the University for Kentucky.
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Knowing what causes dandelions to spread could help us understand how the plants respond to climate change, and could even help us design new ‘soft’ robots.
Known for their fluffiness and uncanny ability to help children tell the time, dandelions provide essential early-Spring food for pollinators like bees, birds, butterflies, and moths.
Their seeds are some of the best flyers in nature, catching the wind and spreading as far as 100 kilometres. Part of how they do this is by tuning their flight depending on the weather.
Each dandelion seed is tethered by a thin tube to around 100 bristles, which form the parachute-like structure. When seeds break free from the flower head, these bundles of hairs catch the wind and carry their seeds. This hairy parachute closes when the air is humid, which often means the wind is weak. In drier, more windy conditions, dandelions widen their parachutes to better catch the wind so the seeds can fly freely.
However until now, nobody knew how they sense and respond to their environment so effectively.
Now an international team including Imperial researchers has uncovered the biomechanical ‘decisions’ behind dandelion seed dispersal.
Their work, published in Nature Communications, found the seed-carrying parachutes open and close using something like actuators – devices that convert signals into movement – without using energy.
The centre of the parachutes senses the humidity of their immediate environment by absorbing water molecules from the air. Responding to these humidity signals, they ‘decide’ to either open their parachutes and fly away, or to close their parachutes and stay put.
They also found that the actuator has a unique radial, tube-like design to which the parachute hairs are attached to ensure simultaneous movement. The actuator changes its shape to either open or close their parachutes.
Imperial author Dr Naomi Nakayama of the Department of Bioengineering who led the work said: “Our findings reveal how the dandelion ensures the survival of its species by making perhaps the most important decision in a plant’s life – to stay or go seek a better habitat.”
Researchers at Imperial, the Universities of Edinburgh, Oxford, Lyon and Ecole Polytechnique de Paris, investigated this using their combination of expertise in plant biology and mechanical engineering.
They placed dandelions into a bespoke, humidity-controlled chamber to study the effects of humidity on the parachute base. They measured humidity’s effects on the actuator using multiple imaging techniques, including an environmental scanning electron microscope.
They found that parachute opening is modulated by the level of humidity in the atmosphere: higher humidity triggered swelling in the actuator and mechanical movement of hairs upwards, which closed the parachutes. Some regions of the actuator swelled noticeably, whereas others, such as the vasculature, barely changed. They observed that the actuator shape change was caused by uptake and release of water droplets, creating a crease in the area the parachute hairs are attached.
They then built a structural computer model of the actuator accounting for these differences and for forces associated with changes in hydration level. Their model agreed quantitatively with most observations, which indicated that differences in capacity to absorb water is key to actuation and therefore parachute opening and closing.
Plant structures can serve as important inspiration for soft robotics as, like plants, these robots don’t use joints or rigid parts to move appendages. Finding out how dandelion parachutes respond to their environment by moving many appendages simultaneously could help engineers create robots that move multiple fingers and arms with very simple yet functional designs. The way the dandelion actuator changes shape in some regions but not others can also teach us about mechanisms of shaping and movement in soft robots and biological tissues.
Dandelion dispersal greatly influences urban and rural ecosystems, and knowing how their flight respond to the environment helps us predict the effects of changing climate.
Dr Nakayama added: “Our work is a great example of what the natural world can teach us about interacting with our environments. It’s also a fantastic piece of multidisciplinary collaboration: bringing varying disciplines together to spark new ways of investigating biological and engineering problems.”
