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NATURE: Water seems to flow freely on Mars

NATURE: Water seems to flow freely on Mars | Amazing Science | Scoop.it
Any areas of water could be off-limits to all but the cleanest spacecraft.


Dark streaks that hint at seasonally flowing water have been spotted near the equator of Mars1. The potentially habitable oases are enticing targets for research. But spacecraft will probably have to steer clear of them unless the craft are carefully sterilized — a costly safeguard against interplanetary contamination that may rule out the sites for exploration.


River-like valleys attest to the flow of water on ancient Mars, but today the planet is dry and has an atmosphere that is too thin to support liquid water on the surface for long. However, intriguing clues suggest that water may still run across the surface from time to time.


In 2011, for example, researchers who analysed images from NASA's Mars Reconnaissance Orbiter (MRO) spacecraft observed dark streaks a few metres wide that appeared and lengthened at the warmest time of the year, then faded in cooler seasons, reappearing in subsequent years2. "This behaviour is easy to understand if these are seeps of water," says planetary scientist Alfred McEwen of the University of Arizona in Tucson, who led that study. "Water will darken most soils."


The streaks, known as recurring slope lineae, initially were found at seven sites in Mars's southern mid-latitudes. The water may have come from ice trapped about a metre below the surface; indeed, the MRO has spotted such ice in fresh impact craters at those latitudes.


McEwen and his colleagues have now found the reappearing streaks near the equator, including in the gargantuan Valles Marineris canyon that lies just south of it. The MRO has turned up 12 new sites — each of which has hundreds or thousands of streaks — within 25 degrees of the equator. The temperatures there are relatively warm throughout the year, says McEwen, and without a mechanism for replenishment, any subsurface ice would probably already have sublimated.


The possibility of running water could put the sites off-limits for future spacecraft unless they are carefully sterilized. The international guidelines of the Committee on Space Research (COSPAR) of the Paris-based International Council for Science say that sites that may host life, called 'special regions', should only be visited by probes that have been thoroughly treated to prevent microbes from hitching a ride from Earth. "You wouldn't want to send a dirty spacecraft to these places because you'd have the potential to not discover what you're looking for, but what you took with you," says John Rummel, chair of COSPAR's panel on planetary protection.


Martian crater records aftermath of Amazon-like flood (Feb 21, 2008) 
Underground radar hunt for life on Mars (May 1, 2005) 
Mars still alive, experts agree (Mar 18, 2005) 
Mars pictures reveal frozen sea (Feb 21, 2005) 
Mars water clues go wider and deeper (Feb 18, 2005) 
Mars hill find hints at wet past (Aug 20, 2004) 
Spirit finds multi-layer hints of past water at Gusev site (Apr 2, 2004) 
Mars: water, water, everywhere ... (Feb 17, 2003) 
Evidence of ancient Martian flood (Jun 21, 2002) 
Vast amounts of subsurface water-ice found on Mars (May 26, 2002) 
Odyssey find sends Mars life hopes soaring (Mar 3, 2002) 
Waterworld Mars: past and future (Dec 8 2001) 
Water clues in Mars rock (Jun 14, 2001) 
A lake like Vostok on Mars? (Feb 18, 2001) 
Meteorite evidence for recent water on Mars (Jan 24, 2001) 
Further signs of liquid water on Mars (Nov 21, 2000) 

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Unlimited, at-home coronavirus testing for your organization

Unlimited, at-home coronavirus testing for your organization | Amazing Science | Scoop.it

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This Wearable Ultrasound Sticker Can Continuously Image Organs for 48 Hours

This Wearable Ultrasound Sticker Can Continuously Image Organs for 48 Hours | Amazing Science | Scoop.it

Ultrasound is a convenient, noninvasive tool for doctors to look inside the human body and check out a person’s liver, heart and other internal structures, as well as the developing fetus of a pregnant patient. But today’s ultrasound imaging technology is large and technical, so it’s only available in healthcare facilities and must be operated by highly trained technicians. Plus, patients, who take time out of their schedules to go to an appointment, have to be covered in a sticky gel.

 

Now, researchers say they’ve developed an innovative solution to some of these challenges. Engineers at the Massachusetts Institute of Technology have unveiled a new adhesive ultrasound patch that’s about the size of a postage stamp and can provide continuous imaging of the body’s inner workings for up to 48 hours. The scientists shared their new technology in a paper published last week in the journal Science.

 

“We believe we’ve opened a new era of wearable imaging,” says Xuanhe Zhao, a mechanical engineer at MIT and one of the study’s authors, in a statement. “With a few patches on your body, you could see your internal organs.” In the past, engineers developing wearable ultrasound technologies have run into issues with image quality and flexibility, but the new MIT stickers seem to have struck the right balance. To create the small devices, which are about three millimeters thick and two square centimeters in size, engineers combined rigid transducers with a stretchy, sticky layer that encapsulates a layer of water-based hydrogel.

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Drosophila embryonic development at single-cell resolution

Drosophila embryonic development at single-cell resolution | Amazing Science | Scoop.it

Scientists have constructed the most complete and detailed single-cell map of embryo development in any animal to date, using the fruit fly as a model organism.

 

Published in the journal Science, this study, co-led by Eileen Furlong at EMBL and Jay Shendure at the University of Washington, harnesses data from more than one million embryonic cells spanning all stages of embryo development and represents a significant advance at multiple levels. This fundamental research also aids scientists' ability to pursue questions like how mutations lead to different developmental defects. In addition, it provides a path to understand the vast non-coding part of our genome that contains most disease-associated mutations.

 

"Just capturing the entirety of embryogenesis—all stages and all cell types—to obtain a more complete view of the cell states and molecular changes that accompany development is a feat in its own right," said Eileen Furlong, Head of EMBL's Genome Biology unit. "But what I'm really excited about is the use of deep learning to obtain a continuous view of the molecular changes driving embryonic development—down to the minute."

 

Embryonic development begins with the fertilization of an egg, followed by a series of cell divisions and decisions that give rise to a very complex multi-cellular embryo that can move, eat, sense, and interact with its environment. Researchers have been studying this process of embryonic development for over a hundred years, but only in the last decade have new technologies enabled scientists to identify molecular changes that accompany cell transitions at a single-cell level. These single-cell studies have raised tremendous excitement as they demonstrated the complexity of cell types in tissues, even identifying new cell types, and revealed their developmental trajectories in addition to underlying molecular changes. However, attempts to profile the entirety of embryo development at single-cell resolution have been out of reach due to many technical challenges in sampling, costs, and technologies.

 

In this regard, the fruit fly (Drosophila melanogaster), a pre-eminent model organism in developmental biologygene regulation, and chromatin biology, has some key advantages when it comes to developing new approaches to address this. Fruit fly embryonic development occurs extremely rapidly; within just 20 hours after fertilization, all tissues have formed, including the brain, gut, and heart, so the organism can crawl and eat. This, in combination with the many discoveries made in fruit flies that have propelled understanding of how genes and their products work, encouraged the Furlong lab and their collaborators to take on this challenge. "Our goal was to obtain a continuous view of all stages of embryogenesis, to capture all of the dynamics and changes as an embryo develops, not just at the level of RNA but also the control elements that regulate this process," said co-author Stefano Secchia, a Ph.D. student in the Furlong group.

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First Monkeypox Deaths Reported – 22,000 Cases Globally

First Monkeypox Deaths Reported – 22,000 Cases Globally | Amazing Science | Scoop.it

Spain reported last Saturday a second death from monkeypox. These are believed to be the first confirmed fatalities from the disease in Europe since its recent spread beyond Africa. The ministry based in Madrid said both fatalities were young men. It reported its first death on Friday, the same day that Brazil also reported its first death from monkeypox.

 

The global monkeypox outbreak has seen more than 22,000 cases in nearly 80 countries since May. There have been 75 suspected deaths in Africa, mostly in Nigeria and Congo, where a more lethal form of monkeypox is spreading than in the West.  In the U.S. and Europe, the vast majority of monkeypox infections have happened in men who have sex with men, though health officials have stressed that anyone can catch the virus. The deaths outside Africa come one week after the World Health Organization declared the monkeypox outbreak a global health emergency.

 

“The notification of deaths due to monkeypox does not change our assessment of the outbreak in Europe. We know that although the disease is self-limiting in most cases, monkeypox can cause severe complications,” said Catherine Smallwood, Senior Emergency Officer at WHO Europe. “With the continued spread of monkeypox in Europe, we will expect to see more deaths. Our goal needs to be on interrupting transmission quickly in Europe and stopping this outbreak,” she said.

 

On Friday, Spain’s health ministry reported 4,298 people were infected with the virus, making it the leading European country for monkeypox cases. Of that total, some 3,500 cases were of men who had had sex with other men. Only 64 were women. The ministry said 120 have needed hospital attention. Smallwood said around 8% of the monkeypox cases in Europe have required hospitalization.

 

Monkeypox has been endemic to parts of Africa for decades. Its leap to Europe and North America was linked by experts to two raves in Belgium and Spain. Spanish health authorities are administering 5,300 vaccines that Spain received from the joint EU vaccine purchase scheme. Health workers say that’s far fewer than the number needed to cover the at-risk groups. But the rush to buy limited vaccines by richer Western countries is putting Africa in danger of being left out. Monkeypox spreads mainly through skin-to-skin contact, but it can also be transmitted through bed sheets used by someone with monkeypox. Symptoms include fever, body aches, chills, fatigue and hives. The illness has been relatively mild in many men. But people can be contagious for weeks, and the lesions can be extremely painful.

 

AP Medical Writer Maria Cheng contributed to this report from London.


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DeepMind's Perceiver AR is a step toward higher AI efficiency

DeepMind's Perceiver AR is a step toward higher AI efficiency | Amazing Science | Scoop.it
 

DeepMind and Google Brain's Perceiver AR architecture reduces the task of computing the combinatorial nature of inputs and outputs into a latent space, but with a twist that the latent space has "causal masking" to add the auto-regressive order of a typical Transformer.

 

One of the alarming aspects of the incredibly popular deep learning segment of artificial intelligence is the ever-larger size of the programs. Experts in the field say computing tasks are destined to get bigger and biggest because scale matters. 

Such bigger and bigger programs are resource hogs, and that is an important issue in the ethics of deep learning for society, a dilemma that has caught the attention of mainstream science journals such as Nature.

 

That's why it's interesting any time that the term efficiency is brought up, as in, Can we make this AI program more efficient?

Scientists at DeepMind, and at Google's Brain division, recently adapted a neural network they introduced last year, Perceiver, to make it more efficient in terms of its computer power requirement. 

 

The new program, Perceiver AR, is named for the "autoregressive" aspect of an increasing number of deep learning programs. Autoregression is a technique for having a machine use its outputs as new inputs to the program, a recursive operation that forms an attention map of how multiple elements relate to one another. 

 

The Transformer, the wildly popular neural network Google introduced in 2017, has this autoregressive aspect. And many models since do, including GPT-3 and the first version of the Perceiver.

 

Perceiver AR follows a second version of Perceiver, called Perceiver IO, introduced in March 2022, and the original Perceiver in 2021. The innovation of the original perceiver was to take the Transformer and tweak it to let it consume all kinds of input, including text sound and images, in a flexible form, rather than being limited to a specific kind of input, for which separate kinds of neural networks are usually developed.

 

Perceiver is one of an increasing number of programs that use auto-regressive attention mechanisms to mix different modalities of input and different task domains. Other examples include Google's Pathways, DeepMind's Gato, and Meta's data2vec. Then, in March, the same team of Andrew Jaegle and colleagues that built Perceiver, introduced the "IO" version, which enhanced the output of Perceiver to accommodate more than just classification, achieving a host of outputs with all kind of structure, ranging from text language output to optical flow fields to audiovisual sequences to symbolic unordered sets. It can even produced movement in the game StarCraft II.

 

Now, detailed in the paper, General-purpose, long-context autoregressive modeling with Perceiver AR, Jaegle and team confront the question of how the models should scale as they become more and more ambitious in those multimodal input and output tasks.  The problem is, the auto-regressive quality of the Transformer, and any other program that builds an attention map from input to output, is that it requires tremendous scale in terms of the a distribution over hundreds of thousands of elements. 

That is the Achilles Heel of attention, the need, precisely, to attend to anything and everything in order assemble the probability distribution that makes for the attention map.

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Synchron completes its endovascular brain implant technology rivaling Elon Musk's Neuralink

Synchron completes its endovascular brain implant technology rivaling Elon Musk's Neuralink | Amazing Science | Scoop.it

Synchron announced today that it completed the first-in-human brain-computer interface (BCI) implant in the U.S. The procedure, performed at Mount Sinai West in New York, represents the first such implant to occur in the U.S. using an endovascular BCI approach, which does not require invasive open-brain surgery.

 

Dr. Shahram Majidi, assistant professor of neurosurgery, neurology and radiology at the Icahn School of Medicine at Mount Sinai, led the procedure, which was performed in the angiography suite with a minimally invasive, endovascular approach. Earlier this year, Synchron’s neuroscience chief explained how this type of catheter delivery could enable better brain implants.

 

It was the first patient implant in Synchron’s Command trial, operating under FDA investigational device exemption to assess a permanently implanted BCI. Command will assess the safety and efficacy of the company’s motor BCI technology, including the Stentrode, in patients with severe paralysis, aiming to enable the patient to control digital devices hands-free. Study outcomes include the use of brain data to control digital devices and achieve improvements in functional independence, according to a news release.

 

“This is an incredibly exciting milestone for the field, because of its implications and huge potential,” Majidi said in the release. “The implantation procedure went extremely well, and the patient was able to go home 48 hours after the surgery.” Notably, the first-in-human implant pulls Synchron ahead of Elon Musk’s Neuralink, which is working to develop an implant placed in the brain through a robot-assisted procedure.

 

Neuralink requires implantation through the skull, and, while Musk and company officials said they planned to file for FDA approval for human trials in 2020, it has yet to receive such approval. Earlier this year, Neuralink and the University of California, Davis, were accused of “egregious violations of the Animal Welfare Act” by the Physicians Committee for Responsible Medicine (PCRM), citing documents obtained through a public records lawsuit. The allegations claimed that Neuralink caused extreme suffering in monkeys.

 

Synchron’s Stentrode is implanted within the major cortex through the jugular vein in a minimally invasive endovascular procedure. Once implanted, it detects and wirelessly transmits motor intent using a proprietary digital language to allow severely paralyzed patients to control personal devices with hands-free point-and-click.

 

The company intends to continue enrollment in the Command trial, while recently reported long-term safety results demonstrated the safe use of the device in four patients out to 12 months in an Australia-based trial. “The first-in-human implant of an endovascular BCI in the U.S. is a major clinical milestone that opens up new possibilities for patients with paralysis,” Synchron CEO and founder Dr. Tom Oxley said. “Our technology is for the millions of people who have lost the ability to use their hands to control digital devices. We’re excited to advance a scalable BCI solution to market, one that has the potential to transform so many lives.”

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Prehistoric Roots of ‘Cold Sore’ Herpes Virus Traced Through Evaluation of Ancient DNA

Prehistoric Roots of ‘Cold Sore’ Herpes Virus Traced Through Evaluation of Ancient DNA | Amazing Science | Scoop.it

Ancient genomes from the herpes virus that commonly causes lip sores – and currently infects some 3.7 billion people globally – have been uncovered and sequenced for the first time by an international team of scientists led by the University of Cambridge.   Latest research suggests that the HSV-1 virus strain behind facial herpes as we know it today arose around five thousand years ago, in the wake of vast Bronze Age migrations into Europe from the Steppe grasslands of Eurasia, and associated population booms that drove rates of transmission. Herpes has a history stretching back millions of years, and forms of the virus infect species from bats to coral.

 

Despite its contemporary prevalence among humans, however, scientists say that ancient examples of HSV-1 were surprisingly hard to find. The authors of the study, published in the journal Science Advances, say the Neolithic flourishing of facial herpes detected in the ancient DNA may have coincided with the advent of a new cultural practice imported from the east: romantic and sexual kissing. “The world has watched COVID-19 mutate at a rapid rate over weeks and months. A virus like herpes evolves on a far grander timescale,” said co-senior author Dr Charlotte Houldcroft, from Cambridge’s Department of Genetics. “Facial herpes hides in its host for life and only transmits through oral contact, so mutations occur slowly over centuries and millennia. We need to do deep time investigations to understand how DNA viruses like this evolve,” she said. “Previously, genetic data for herpes only went back to 1925.” The team managed to hunt down herpes in the remains of four individuals stretching over a thousand-year period, and extract viral DNA from the roots of teeth. Herpes often flares up with mouth infections: at least two of the ancient cadavers had gum disease and a third smoked tobacco.

 

The oldest sample came from an adult male excavated in Russia’s Ural Mountain region, dating from the late Iron Age around 1,500 years ago. Two further samples were local to Cambridge, UK. One a female from an early Anglo-Saxon cemetery a few miles south of the city, dating from 6-7th centuries AD. The other a young adult male from the late 14th century, buried in the grounds of medieval Cambridge’s charitable hospital (later to become St. John’s College), who had suffered appalling dental abscesses. The final sample came from a young adult male excavated in Holland: a fervent clay pipe smoker, most likely massacred by a French attack on his village by the banks of the Rhine in 1672. “We screened ancient DNA samples from around 3,000 archaeological finds and got just four herpes hits,” said co-lead author Dr Meriam Guellil, from Tartu University’s Institute of Genomics. “By comparing ancient DNA with herpes samples from the 20th century, we were able to analyse the differences and estimate a mutation rate, and consequently a timeline for virus evolution,” said co-lead author Dr Lucy van Dorp, from the UCL Genetics Institute. Co-senior author Dr Christiana Scheib, Research Fellow at St. John’s College, University of Cambridge, and Head of the Ancient DNA lab at Tartu University, said: “Every primate species has a form of herpes, so we assume it has been with us since our own species left Africa.”

 

“However, something happened around five thousand years ago that allowed one strain of herpes to overtake all others, possibly an increase in transmissions, which could have been linked to kissing.” The researchers point out that the earliest known record of kissing is a Bronze Age manuscript from South Asia, and suggest the custom – far from universal in human cultures – may have travelled westward with migrations into Europe from Eurasia. In fact, centuries later, the Roman Emperor Tiberius tried to ban kissing at official functions to prevent disease spread, a decree that may have been herpes-related. However, for most of human prehistory, HSV-1 transmission would have been “vertical”: the same strain passing from infected mother to newborn child. Two-thirds of the global population under the age of 50 now carry HSV-1, according to the World Health Organization.

 

For most of us, the occasional lip sores that result are embarrassing and uncomfortable, but in combination with other ailments – sepsis or even COVID-19, for example – the virus can be fatal. In 2018, two women died of HSV-1 infection in the UK following Caesarean births. “Only genetic samples that are hundreds or even thousands of years old will allow us to understand how DNA viruses such as herpes and monkeypox, as well as our own immune systems, are adapting in response to each other,” said Houldcroft. The team would like to trace this hardy primordial disease even deeper through time, to investigate its infection of early hominins. “Neanderthal herpes is my next mountain to climb,” added Scheib.

 

Publisjhed in Science Advances (July 27, 2022):

https://doi.org/10.1126/sciadv.abo4435 


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How Long is COVID Infectious? What Scientists Know So Far

How Long is COVID Infectious? What Scientists Know So Far | Amazing Science | Scoop.it

Those with SARS-CoV-2 are often advised to isolate for only a few days. But evidence is mounting that some people can continue to pass on the virus for much longer.  When the US Centers for Disease Control and Prevention (CDC) halved its recommended isolation time for people with COVID-19 to five days back in December, it said that the change was motivated by science. Specifically, the CDC said that most SARS-CoV-2 transmission occurs early in the course of the illness, in the one to two days before the onset of symptoms and for two to three days after. Many scientists disputed that decision then and they continue to do so. Such dissent is bolstered by a series of studies confirming that many people with COVID-19 remain infectious well into the second week after they first experience symptoms. Reductions in the length of the recommended isolation period — now common around the world — are driven by politics, they say, rather than any reassuring new data. “The facts of how long people are infectious for have not really changed,” says Amy Barczak, an infectious-disease specialist at Massachusetts General Hospital in Boston. “There is not data to support five days or anything shorter than ten days [of isolation].” Barczak’s own research, published on the medRxiv preprint server, suggests that one-quarter of people who have caught the Omicron variant of SARS-CoV-2 could still be infectious after eight days.

A numbers game

Although the question is simple — for how long is someone with COVID-19 contagious? — experts caution that the answer is complicated. “We always think of it as a black and white thing … if somebody’s infectious or not infectious — but in reality, it’s a numbers game and a probability,” says Benjamin Meyer, a virologist at the University of Geneva in Switzerland.  And that numbers game has shifting rules and baselines. Emerging variants, vaccination and varying levels of natural immunity provoked by previous infection can all influence how quickly someone can clear the virus from their system, Meyer says, and this ultimately dictates when they stop being infectious. Behavioural factors matter as well. People who feel unwell tend to mix less with others, he adds, so the severity of someone’s symptoms can influence how likely they are to infect others. Something most scientists are confident about is that PCR tests can return a positive result even after someone is no longer infectious. This probably occurs when the tests, which detect viral RNA, pick up non-infectious remnants left behind after most of the live virus has been eliminated.By contrast, lateral flow (or ‘rapid  antigen’) tests offer a better guide to infectiousness, because they detect proteins produced by actively replicating virus. “There’s still all of these things that we’re not exactly sure about, but if I had to sum it up in one very concise message, it would be that if you’re antigen positive, you shouldn't go out and interact closely with people who you don’t want to be infected,” says Emily Bruce, a microbiologist and molecular geneticist at the University of Vermont in Burlington. What about somebody who has tested negative on a lateral flow test for a few days but still has a fever and a hacking cough? Bruce says it’s important to remember that although lingering symptoms might look and sound serious, they do not indicate continued infectiousness. “You can definitely have symptoms for longer than you test positive on lateral flow,” she says. “And I think that’s because many of the symptoms are caused by the immune system and not directly by the virus itself.”

Transmission tests

In countries such as the United Kingdom, the relaxation of the isolation guidelines coincided with the withdrawal of free lateral flow tests. So, assuming that many of the people who follow the new recommendations are going to stop isolating after five days without testing, scientists have been investigating in particular how many people with COVID-19 are likely to remain infectious after this point. It’s not practical to track direct onward transmission of the virus from large numbers of people and to measure how it reduces over time, so researchers instead rely on proxy measurements to determine the point at which they would expect people to stop being contagious.  Researchers with access to a high-security biosafety level 3 laboratory — as Barczak has — can do this by running experiments to test whether live SARS-CoV-2 can be cultured from samples taken from patients over several consecutive days. “If you’re still shedding virus that we can culture out of your nose, there’s at least a good chance you’re still infectious to other people,” she says. As different variants have emerged and various research groups have done these experiments, Barczak says, a consensus has emerged that it’s very unusual for people to shed culturable virus after ten days. “So, it’s very unusual for people to stay infectious after ten days,” she says. Other studies take a step further away from the real world, and use levels of viral RNA measured by PCR tests to infer whether someone is infectious. This makes it easier to work with large sample sizes. For example, a project run by the Crick Institute and University College Hospital, both in London, can draw on PCR tests carried out on more than 700 participants, obtained from when symptoms developed. A study based on this group suggests that significant numbers of people retain viral loads high enough to trigger onward infection at days seven to ten, irrespective of the variant type or how many vaccine doses people had received. The study was published on the medRxiv preprint server on 10 July. “We’re not measuring live virus, but there is now a huge amount of work in the literature that provides a pretty good mapping of what constitutes a viral load likely to yield infectious virus,” says David LV Bauer, a virologist at the Crick Institute who is co-investigator on that study. “So while it’s not a perfect picture, it’s a reasonable one.”

‘Rebound phenomenon’

Yonatan Grad, an infectious-disease specialist at the Harvard T.H. Chan School of Public Health in Boston, Massachusetts, who has worked on similar PCR-based studies of infectiousness, agrees that ten days is a useful rule of thumb for when people should no longer be contagious. But he cautions that a small number of people could still be infectious beyond that point.  Some such cases in the United States have been linked to the common antiviral drug Paxlovid (nirmatrelvir–ritonavir), he says. “There’s a rebound phenomenon where people will see that their symptoms seem to resolve and they may even test negative on a rapid test, but then a few days later symptoms and the virus come back.” Barczak says this is one of the key questions that researchers are now studying. “Antivirals change the dynamics of symptoms, change the dynamics of the immune response and change the dynamics of how you shed,” she says. “I think this is really important, because people are out in the world thinking they're not infectious after ten days. But if they have Paxlovid rebound they might be.”

 

Published in Nature  (July 26, 2022):

https://doi.org/10.1038/d41586-022-02026-x 


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As 1.5˚C warming nears, interest in sun-dimming tech heats up

As 1.5˚C warming nears, interest in sun-dimming tech heats up | Amazing Science | Scoop.it

As fossil fuel use continues to climb and a hotter planet edges closer to passing any safety limits, some scientists are exploring a controversial technological stopgap: spraying chemicals into the atmosphere to reflect away some of the sun's sunlight. Deploying the technology, using special planes, would be relatively cheap and simple, costing a few billion dollars a year, its backers sayAnd it could - if maintained - hold down global average temperatures, potentially staving off increasingly deadly climate-change impacts such as heatwaves, they argue.

 

"I do see it as a likely option" if plans to cut emissions fall short and dangers grow, said Emmi Yonekura, a researcher on the risks of climate "geoengineering" at RAND Corporation, a military-focused policy think-tank, during an online event.  But the technology, which mimics the sky-darkening effect of volcanic eruptions, also carries serious and unpredictable risks, critics say - with some scientists so worried that they believe research should stop and outdoor tests be banned. Threats range from potential shifts in rainfall patterns that could spur worsening hunger to rapid, uncontrollable temperature rise if the technology's use is suddenly stopped. The availability of such a planet-cooling option could also give climate polluters an unwarranted green-light to carry on - even though "stratospheric aerosol injection" (SAI) would only mask the problem, not solve it.

 

Early efforts to create rules to govern its use show signs of stalling, critics warn, making it more likely that one powerful state or even individual could go it alone, potentially to the detriment of others, sparking conflict. "The more we see extreme events like hurricanes, wildfires, also just heatwaves that have acute impacts - those may motivate key actors to try to protect themselves," said Jonathan Wiener, co-director of the Duke Center on Risk. Unilateral use of the technology "might be very difficult to deal with geopolitically", said Wiener, a law and environmental policy professor at Duke University in the United States. Where scientists and policy experts agree is that, as the world speeds towards the lower 1.5 degree-Celsius warming limit set in the Paris Agreement, serious thinking about what happens if the Earth's climate breaks down must happen - fast.

 

"We are now entering a situation where the likelihood of overshooting 1.5˚C degrees is higher than not overshooting it," said Janos Pasztor, executive director of the Carnegie Climate Governance Initiative (C2G), a think-tank focused on how to manage "climate-altering technologies".  With the world still "very far" from taking the aggressive steps needed to limit climate change, the impacts of a warming planet will worsen - and in some cases be "catastrophic", he warned. That means more extreme ways to cool the climate are now on the table. Pasztor told an online event it was important to weigh up the risks of taking such measures against not taking them. "Simply not doing either anything or enough ... in itself has huge risks," he said.

TIPPING POINTS

To effectively limit warming, climate-heating emissions - largely from burning fossil fuels - need to fall 45% globally by 2030, scientists say. Instead, they are still rising, as oil and gas use continues to grow and investment in renewable energy alternatives lags. Scientists with the Intergovernmental Panel on Climate Change (IPCC) have warned that if global average temperatures exceed 1.5C above pre-industrial times, the world could see changes that will be hard to adapt to.  Those could include surging hunger as crops fail, as well as growing water shortages, migration and conflict. Deaths and financial losses from worsening heatwaves, wildfires, droughts, floods, hurricanes and sea level rise could also increase, affecting rich countries as well as poor.

 

More heat could melt Arctic and ocean permafrost that holds climate-heating methane, turbo-charging temperature rise and launching the planet into a vicious heating cycle that would be hard to reverse, scientists say. Some impacts of passing 1.5˚C - such as likely losses of many of the world's coral reefs - "will be irreversible, even if global warming is reduced", warned Thelma Krug, a climate scientist and vice chair of the IPCC.  With the World Meteorological Organization projecting that the 1.5C threshold could be passed, at least temporarily, within five years, a Climate Overshoot Commission of 16 world leaders was launched in May. 

It will look at controversial sun-dimming technologies, alongside efforts to remove carbon dioxide from the atmosphere and to adapt to new conditions.

 

SAI research has won some powerful financial backers, including Bill Gates and a range of venture capitalists and philanthropists, including at least one former oil executive.

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Studies link COVID-19 to wildlife sales at Chinese market, find alternative scenarios extremely unlikely

Studies link COVID-19 to wildlife sales at Chinese market, find alternative scenarios extremely unlikely | Amazing Science | Scoop.it
Analyses based on locations and viral sequencing of early cases indicate the COVID-19 pandemic started in Wuhan's Huanan Seafood Wholesale Market, with two separate jumps from animals to humans.

 

An international team of researchers has confirmed that live animals sold at the Huanan Seafood Wholesale Market were the likely source of the COVID-19 pandemic that has claimed 6.4 million lives since it began nearly three years ago. Led by University of Arizona virus evolution expert Michael Worobey, international teams of researchers have traced the start of the pandemic to the market in Wuhan, China, where foxes, raccoon dogs and other live mammals susceptible to the virus were sold live immediately before the pandemic began. Their findings were published Tuesday in two papers in the journal Science.

 

The publications, which have since gone through peer review and include additional analyses and conclusions, virtually eliminate alternative scenarios that have been suggested as origins of the pandemic. Moreover, the authors conclude that the first spread to humans from animals likely occurred in two separate transmission events in the Huanan market in late November 2019.

 

One study scrutinized the locations of the first known COVID-19 cases, as well as swab samples taken from surfaces at various locations at the market. The other focused on genomic sequences of SARS-CoV-2 from samples collected from COVID-19 patients during the first weeks of the pandemic in China.

 

One of the papers, led by Worobey and Kristian Andersen at Scripps Research Institute in San Diego, California, examined the geographic pattern of COVID-19 cases in the first month of the outbreak, December 2019. The team was able to determine the locations of almost all of the 174 COVID-19 cases identified by the World Health Organization that month, 155 of which were in Wuhan. Analyses showed that these cases were clustered tightly around the Huanan market, whereas later cases were dispersed widely throughout Wuhan -- a city of 11 million people. Notably, the researchers found that a striking percentage of early COVID patients with no known connection to the market -- meaning they neither worked there nor shopped there -- turned out to live near the market. This supports the idea that the market was the epicenter of the epidemic, Worobey said, with vendors getting infected first and setting off a chain of infections among community members in the surrounding area.

 

"In a city covering more than 3,000 square miles, the area with the highest probability of containing the home of someone who had one of the earliest COVID-19 cases in the world was an area of a few city blocks, with the Huanan market smack dab inside it," said Worobey, who heads UArizona Department of Ecology and Evolutionary Biology.

 

This conclusion was supported by another finding: When the authors looked at the geographical distribution of later COVID cases, from January and February 2020, they found a "polar opposite" pattern, Worobey said. While the cases from December 2019 mapped "like a bullseye" on the market, the later cases coincided with areas of the highest population density in Wuhan.

"This tells us the virus was not circulating cryptically," Worobey said. "It really originated at that market and spread out from there."

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Supermassive black holes with varying light signatures are actually in different stages of their life cycle

Supermassive black holes with varying light signatures are actually in different stages of their life cycle | Amazing Science | Scoop.it

Black holes with varying light signatures but that were thought to be the same objects being viewed from different angles are actually in different stages of the life cycle, according to a study led by Dartmouth researchers. The research on black holes known as "active galactic nuclei," or AGNs, says that it definitively shows the need to revise the widely used "unified model of AGN" that characterizes supermassive black holes as all having the same properties. The study, published in The Astrophysical Journal, provides answers to a nagging space mystery and should allow researchers to create more precise models about the evolution of the universe and how black holes develop.

 

"These objects have mystified researchers for over a half-century," said Tonima Tasnim Ananna, a postdoctoral research associate at Dartmouth and lead author of the paper. "Over time, we've made many assumptions about the physics of these objects. Now we know that the properties of obscured black holes are significantly different from the properties of AGNs that are not as heavily hidden." Supermassive black holes are believed to reside at the center of nearly all large galaxies, including the Milky Way. The objects devour galactic gas, dust and stars, and they can become heavier than small galaxies.

 

For decades, researchers have been interested in the light signatures of active galactic nuclei, a type of supermassive black hole that is "accreting," or in a rapid growth stage. Beginning in the late 1980s, astronomers realized that light signatures coming from space ranging from radio wavelengths to X-rays could be attributed to AGNs. It was assumed that the objects usually had a doughnut-shaped ring -- or "torus" -- of gas and dust around them.

 

The different brightness and colors associated with the objects were thought to be the result of the angle from which they were being observed and how much of the torus was obscuring the view. From this, the unified theory of AGNs became the prevalent understanding. The theory guides that if a black hole is being viewed through its torus, it should appear faint. If it is being viewed from below or above the ring, it should appear bright. According to the current study, however, the past research relied too heavily on data from the less obscured objects and skewed research results.

The new study focuses on how quickly black holes are feeding on space matter, or their accretion rates. The research found that the accretion rate does not depend upon the mass of a black hole, it varies significantly depending on how obscured it is by the gas and dust ring. "This provides support for the idea that the torus structures around black holes are not all the same," said Ryan Hickox, professor of physics and astronomy and a co-author of the study. "There is a relationship between the structure and how it is growing."

 

The result shows that the amount of dust and gas surrounding an AGN is directly related to how much it is feeding, confirming that there are differences beyond orientation between different populations of AGNs. When a black hole is accreting at a high rate, the energy blows away dust and gas. As a result, it is more likely to be unobscured and appear brighter. Conversely, a less active AGN is surrounded by a denser torus and appears fainter. "In the past, it was uncertain how the obscured AGN population varied from their more easily observable, unobscured counterparts," said Ananna.

 

"This new research definitively shows a fundamental difference between the two populations that goes beyond viewing angle." The study stems from a decade-long analysis of nearby AGNs detected by Swift-BAT, a high-energy NASA X-ray telescope. The telescope allows researchers to scan the local universe to detect obscured and unobscured AGNs.

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Discovery Reveals Large, Year-Round Ozone Hole Over Tropics

Discovery Reveals Large, Year-Round Ozone Hole Over Tropics | Amazing Science | Scoop.it

An ozone hole, seven times larger than the Antarctic ozone hole, is currently sitting over tropical regions and has been since the 1980s, according to a Canadian researcher. In AIP Advances, Qing-Bin Lu, a scientist from the University of Waterloo in Ontario, Canada, reveals a large, all-season ozone hole -- defined as an area of ozone loss larger than 25% compared with the undisturbed atmosphere -- in the lower stratosphere over the tropics comparable in depth to that of the well-known springtime Antarctic hole, but its area is roughly seven times greater.

 

"The tropics constitute half the planet's surface area and are home to about half the world's population," said Lu. "The existence of the tropical ozone hole may cause a great global concern. "The depletion of the ozone layer can lead to increased ground-level UV radiation, which can increase risk of skin cancer and cataracts in humans, as well as weaken human immune systems, decrease agricultural productivity, and negatively affect sensitive aquatic organisms and ecosystems."

 

Lu's observation of the ozone hole comes as a surprise to his peers in the scientific community, since it was not predicted by conventional photochemical models. His observed data agree well with the cosmic-ray-driven electron reaction (CRE) model and strongly indicate the identical physical mechanism working for both Antarctic and tropical ozone holes.

 

As with the polar ozone hole, approximately 80% of the normal ozone value is found to be depleted at the center of the tropical ozone hole. Preliminary reports show ozone depletion levels over equatorial regions are already endangering large populations and the associated UV radiation reaching these regions is far greater than expected.

 

In the mid-1970s, atmospheric research suggested the ozone layer, which absorbs most of the sun's ultraviolet radiation, might be depleted because of industrial chemicals, primarily chlorofluorocarbons (CFCs). The 1985 discovery of the Antarctic ozone hole confirmed CFC-caused ozone depletion. Although bans on such chemicals have helped slow ozone depletion, evidence suggests ozone depletion persisted.

 

Lu said the tropical and polar ozone holes play a major role in cooling and regulating stratospheric temperatures, mirroring the formation of three "temperature holes" in the global stratosphere. He said this finding may prove crucial to better understanding global climate change. Lu's discovery builds on previous studies of the CRE-initiated ozone-depleting mechanism that he and his colleagues originally proposed about two decades ago. "The present discovery calls for further careful studies of ozone depletion, UV radiation change, increased cancer risks, and other negative effects on health and ecosystems in the tropical regions," said Lu.

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Micron Is First to Deliver 3D Flash Chips With More Than 200 Layers

Micron Is First to Deliver 3D Flash Chips With More Than 200 Layers | Amazing Science | Scoop.it

Micron Technology says it has reached volume production of a 232-layer NAND flash-memory chip. It’s the first such chip to pass the 200-layer mark, and it’s been a tight race. Competitors are currently providing 176-layer technology, and some have said they are on track to follow Micron’s skyward move or already have working chips in hand.

The new Micron tech as much as doubles the density of bits stored per unit area versus competing chips, packing in 14.6 gigabits per square millimeter. Its 1-terabit chips are bundled into 2-terabyte packages, each of which is barely more than a centimeter on a side and can store about two weeks worth of 4K video. With 81 trillion gigabytes (81 zettabytes) of data generated in 2021 and International Data Corp. (IDC) predicting 221 ZB in 2026, “storage has to innovate to keep up,” says Alvaro Toledo, Micron’s vice president of data-center storage.

The move to 223 layers is a combination and extension of many technologies Micron has already deployed. To get a handle on them, you need to know the basic structure and function of 3D NAND flash. The chip itself is made up of a bottom layer of CMOS logic and other circuitry that’s responsible for controlling reading and writing operations and getting data on and off the chip as quickly and efficiently as possible. Improvements to this layer, such as optimizing the path data travels and reducing the capacitance of the chip’s inputs and outputs, yielded a 50 percent improvement in the data transfer rate to 2.4 Gb/s.

Above the CMOS are layers upon layers of NAND flash cells. Unlike other devices, Flash-memory cells are built vertically. They start as a (relatively) deep, narrow hole etched through alternating layers of conductor and insulator. Then the holes are filled with material and processed to form the bit-storing part of the device. It’s the ability to reliably etch and fill the holes through all those layers that’s a key limit to the technology. Instead of etching through all 232 layers in one go, Micron’s process builds them in two parts and stacks one atop the other. Even so, “it’s an astounding engineering feat,” says Alvaro. “That was one of the biggest challenges we overcame.”

According to Toledo, there is a path toward even more layers in future NAND chips. “There are definitely challenges,” he says. But “we haven’t seen the end of that path.” In addition to adding more and more layers, NAND flash makers have been increasing the density of stored bits by packing multiple bits into a single device. Each of the Micron chip’s memory cells is capable of storing three bits per cell. That is, the charge stored in each cell produces a distinct enough effect to discern eight different states. Though 3-bit-per-cell products (called TLC) are the majority, four-bit products (called QLC) are also available. One QLC chip presented by Western Digital researchers at the IEEE International Solid State Circuits Conference earlier this year achieved a 15 Gb/mm2 areal density in a 162-layer chip. And Kioxia engineers reported 5-bit cells last month at the IEEE Symposium on VLSI Technology and Circuits. There has even been a 7-bit cell demonstrated, but it required dunking the chip in 77-kelvin liquid nitrogen.

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Speeding up evolution at the genome level by alternative chromosome configuration

Speeding up evolution at the genome level by alternative chromosome configuration | Amazing Science | Scoop.it

A research team led by André Marques at the Max Planck Institute for Plant Breeding Research in Cologne, Germany, has uncovered the profound effects of an atypical mode of chromosome arrangement on genome organization and evolution. Their findings are published in the journal Cell.

 

In each individual cell in our body, our DNA, the molecule carrying the instructions for development and growth, is packaged together with proteins into structures called chromosomes. Full sets of chromosomes together constitute the genome, the entire genetic information of an organism. In most organisms, including us, chromosomes appear as X-shaped structures when they are captured in their condensed, duplicated states in preparation for cell division. Indeed, these structures may be among the most iconic in all of science. The X shape is due to a constricted region called the centromere that serves to connect sister chromatids, which are the identical copies formed by the DNA replication of a chromosome.

 

Most studied organisms are 'monocentric', meaning that centromeres are restricted to a single region on each chromosome. Several animal and plant organisms, however, show a very different centromere organization: instead of one solitary constriction as in the classic X-shaped chromosomes, chromosomes in these organisms harbor multiple centromeres that are arranged in a line from one end of a sister chromatid to the other. Thus, these chromosomes lack a primary constriction and the X shape, and species with such chromosomes are known as 'holocentric', from the ancient Greek word hólos meaning 'whole'.

 

A new study led by André Marques from the Max Planck Institute for Plant Breeding Research in Cologne, Germany, now reveals the striking effects of this non-classical mode of chromosome organization on genome architecture and evolution. To determine how holocentricity affects the genome, Marques and his team used highly accurate DNA sequencing technology to decode the genomes of three closely related holocentric beak-sedges, grass-like flowering plants found worldwide that are often the first conquerors of new habitats. For reference, the team also decoded the genome of their most closely related monocentric relative. Thus, comparing the holocentric beak-sedges with their monocentric relative allowed the authors to attribute any differences they observed to the effects of holocentricity.

 

Their analysis reveals striking differences in genome organization and chromosome behavior in holocentric organisms. They found that centromere function is distributed across hundreds of small centromere domains in holocentric chromosomes. While in monocentric organisms, genes are largely concentrated distant from centromeres and the regions immediately around them, in holocentric species they are uniformly distributed over the whole length of chromosomes. Further, in monocentric species chromosomes are known to engage in a high degree of intermingling with each other during cell division, a property which appears to play a role in regulating gene expression. Notably, these long-range interactions were sharply diminished in the beak-sedges with holocentromeres. Thus, holocentricity fundamentally affects genome organization as well as how chromosomes behave during cell division.

 

In holocentric organisms, almost any given chromosomal fragment will harbor a centromere and will thus have proper centromere function, which is not true for monocentric species. In this way, holocentromeres have been thought to stabilize chromosomal fragments and fusions and thus promote rapid genome evolution, or the ability of an organism to make prompt, wholesale changes to its DNA. In one of the beak-sedges they analyzed, Marques and his team could show that chromosome fusions facilitated by holocentromeres allowed this species to maintain the same chromosome number even after quadruplication of the entire genome. In another of their analyzed beak-sedges, a species with only two chromosomes, the lowest of any plant, holocentricity was found to be responsible for the dramatic reduction in chromosome number. Thus, holocentric chromosomes may allow the formation of news species through rapid evolution at genome-level.

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Stem cell-derived mouse embryos develop within an extra-embryonic yolk sac to form anterior brain regions and a beating heart

Stem cell-derived mouse embryos develop within an extra-embryonic yolk sac to form anterior brain regions and a beating heart | Amazing Science | Scoop.it

Embryo-like structures generated from stem cells can achieve varying developmental milestones, but none have been shown to progress through gastrulation, neurulation, and organogenesis.

 

Just recently scientists were able to show that ETiX mouse embryos, established from embryonic stem cells aggregated with trophoblast stem cells and inducible extraembryonic endoderm stem cells, can develop through gastrulation and beyond to undertake neural induction and generate the progenitors needed to create the entire organism. The head-folds of ETiX embryos show anterior expression of Otx2, defining forebrain and midbrain regions that resemble those of the natural mouse embryo.

 

ETiX embryos also develop beating hearts, trunk structures comprising a neural tube and somites, tail buds containing neuromesodermal progenitors and primordial germ cells, and gut tubes derived from definitive endoderm. A fraction of ETiX embryos show neural tube abnormalities, which can be partially rescued by treatment with the metabolically active form of folic acid, reminiscent of common birth defects and therapies in humans. Notably, ETiX embryos also develop a yolk sac with blood islands. Overall, ETiX embryos uniquely recapitulate natural embryos, developing further than any other stem-cell derived model, through multiple post-implantation stages and within extra-embryonic membranes.

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3D kirigami building blocks to make dynamic metamaterials

3D kirigami building blocks to make dynamic metamaterials | Amazing Science | Scoop.it
A new approach to producing metamaterials draws on kirigami techniques to make three-dimensional, reconfigurable building blocks that can be used to create complex, dynamic structures. Because the design approach is modular, these structures are easy to both assemble and disassemble.

 

Kirigami, the ancient paper art of cutting, has recently emerged as a new approach to construct metamaterials with novel properties imparted by cuts. However, most studies are limited to thin sheets-based 2D kirigami metamaterials with specific forms and limited reconfigurability due to planar connection constraints of cut units.

 

Now, 3D modular kirigami is introduced by cutting bulk materials into spatially closed-loop connected cut cubes to construct a new class of 3D kirigami metamaterials. The module is transformable with multiple degrees of freedom that can transform into versatile distinct daughter building blocks. Their conformable assembly creates a wealth of reconfigurable and disassemblable metamaterials with diverse structures and unique properties, including reconfigurable 1D column-like materials, 2D lattice-like metamaterials with phase transition of chirality, as well as 3D frustration-free multilayered metamaterials with 3D auxetic behaviors and programmable deformation modes. This study largely expands the design space of kirigami metamaterials from 2D to 3D.

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A “Nano-Robot” Built Entirely from DNA to Explore Cell Processes

A “Nano-Robot” Built Entirely from DNA to Explore Cell Processes | Amazing Science | Scoop.it

Constructing a tiny robot from DNA and using it to study cell processes invisible to the naked eye. You would be forgiven for thinking it is science fiction, but it is in fact the subject of serious research by scientists from Inserm, CNRS and Université de Montpellier at the Structural Biology Center in Montpellier. This highly innovative "nano-robot" should enable closer study of the mechanical forces applied at microscopic levels, which are crucial for many biological and pathological processes. It is described in a new study published in Nature Communications.

 

All cells are subject to mechanical forces exerted on a microscopic scale, triggering biological signals essential to many cell processes involved in the normal functioning of our body or in the development of diseases. For example, the feeling of touch is partly conditional on the application of mechanical forces on specific cell receptors (the discovery of which was this year rewarded by the Nobel Prize in Physiology or Medicine). In addition to touch, these receptors that are sensitive to mechanical forces (known as mechanoreceptors) enable the regulation of other key biological processes such as blood vessel constriction, pain perception, breathing or even the detection of sound waves in the ear, etc.

 

The dysfunction of this cellular mechanosensitivity is involved in many diseases -- for example, cancer: cancer cells migrate within the body by sounding and constantly adapting to the mechanical properties of their microenvironment. Such adaptation is only possible because specific forces are detected by mechanoreceptors that transmit the information to the cell cytoskeleton.

 

At present, our knowledge of these molecular mechanisms involved in cell mechanosensitivity is still very limited. Several technologies are already available to apply controlled forces and study these mechanisms, but they have a number of limitations. In particular, they are very costly and do not allow us to study several cell receptors at a time, which makes their use very time-consuming if we want to collect a lot of data.

 

DNA origami structures

In order to propose an alternative, the research team led by Inserm researcher Gaëtan Bellot at the Structural Biology Center (Inserm/CNRS/Université de Montpellier) decided to use the DNA origami method. This enables the self-assembly of 3D nanostructures in a pre-defined form using the DNA molecule as construction material. Over the last ten years, the technique has allowed major advances in the field of nanotechnology. This enabled the researchers to design a "nano-robot" composed of three DNA origami structures. Of nanometric size, it is therefore compatible with the size of a human cell. It makes it possible for the first time to apply and control a force with a resolution of 1 piconewton, namely one trillionth of a Newton -- with 1 Newton corresponding to the force of a finger clicking on a pen. This is the first time that a human-made, self-assembled DNA-based object can apply force with this accuracy.

 

The team began by coupling the robot with a molecule that recognizes a mechanoreceptor. This made it possible to direct the robot to some of our cells and specifically apply forces to targeted mechanoreceptors localized on the surface of the cells in order to activate them. Such a tool is very valuable for basic research, as it could be used to better understand the molecular mechanisms involved in cell mechano-sensitivity and discover new cell receptors sensitive to mechanical forces. Thanks to the robot, the scientists will also be able to study more precisely at what moment, when applying force, key signaling pathways for many biological and pathological processes are activated at cell level.

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US-European Satellite Will Make World’s First Global Freshwater Survey

US-European Satellite Will Make World’s First Global Freshwater Survey | Amazing Science | Scoop.it

The Surface Water and Ocean Topography mission will make measurements of over 95% of Earth’s lakes, rivers, and reservoirs.

Water is life, but for all its importance, humanity has a surprisingly limited view of Earth’s freshwater bodies. Researchers have reliable water level measurements for only a few thousand lakes around the world, and little to no data on some of the planet’s important river systems. The upcoming Surface Water and Ocean Topography (SWOT) satellite will fill that enormous gap. By helping to provide a better understanding of Earth’s water cycle, it will both aid in better management of water resources and expand knowledge of how climate change affects lakes, rivers, and reservoirs.

 

A collaboration between NASA and the French space agency Centre National d’Études Spatial (CNES), with contributions from the Canadian Space Agency and the United Kingdom Space Agency, SWOT is scheduled to launch in November from Vandenberg Space Force Base in California. Engineers and technicians are finishing up work on the satellite in a facility run by Thales Alenia Space in Cannes, France.

 

SWOT has several key tasks, including measuring the height of water bodies on Earth’s surface. Over the ocean, the satellite will be able to “see” features like eddies less than 60 miles (100 kilometers) across – smaller than those that previous sea level satellites could observe. SWOT will also measure more than 95% of Earth’s lakes larger than 15 acres (6 hectares) and rivers wider than 330 feet (100 meters) across.

 

“Current databases maybe have information on a couple thousand lakes around the world,” said Tamlin Pavelsky, the NASA freshwater science lead for SWOT, based at the University of North Carolina, Chapel Hill. “SWOT will push that number to between 2 million and 6 million.”

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Pluto and Charon are a binary planet system

Pluto and Charon are a binary planet system | Amazing Science | Scoop.it
Charon is not considered a moon or satellite of Pluto, but is considered to be a companion. Why is is that so? And what is Charon like?

 

Of all the planets and moons in the solar system, Pluto and Charon are the two which resemble each other the most closely. They are almost the same size, and they are very close together. They are so close together that they orbit the center of mass between them, and the center of mass goes around the sun. Pluto and Charon are so close that they may even share an atmosphere. Molecules may be drawn off Pluto and turn to solids on the surface of Charon.

 

The only other planet and moon in the solar system which could be a double planet are the Earth and the Moon. As in the case of the Earth and the Moon, the origin of such a system is hard to explain. The explanation which seems best is that some large object struck Pluto (and the Earth) and tore out a blob which became Charon (and the Moon) from the crust of the planet. In the case of the Moon, the Moon seems to be made of material very much like the Earth's crust and not like the Earth's more metallic interior. Likewise Charon may be made of more icy material which resembles Pluto's surface, rather than the more rocky interior of Pluto.

 

Charon's Discovery

The moon, Charon, was discovered by James Christy in 1978. He proposed naming the moon ‘Charon’ because it was similar to his wife’s nickname ‘Char’, short for Charlene. He wanted the soft ‘ch’, but the mythological connection of ‘Karon’, the ferryman of the dead, to Pluto, the god of the underworld, made hard ‘k’ the more obvious choice. So one will hear both pronunciations used. NASA and the New Horizons team members generally use Christy’s choice of ‘Charon’.

 

With a diameter of about 1200 kilometers, Charon is big enough for gravity to have made it spherical. Charon has a similar bulk composition to Pluto—ice and rock—but its lower density of 1700 kilograms per cubic meter tells us that it’s more ice-rich than Pluto. Data from the New Horizons mission determined that Charon’s surface is mostly water ice. This is a big difference with Pluto, whose surface is mainly nitrogen and methane ices.

 

Why Is Charon a Companion, Not a Moon?

We usually think of moons as orbiting an object at the center, similar to how we think of planets as orbiting the Sun at the center. But this isn’t exactly right. What really happens is that two gravitationally bound objects will both orbit their center of mass.

The center of mass is the location that represents the average position of the mass in the system. If one of the objects is much bigger than the other, then the center of mass is very close to the center of the large object and it looks like the small object is orbiting about the center of the large object. This is what happens in the case of all of the moon systems orbiting their planets. But Charon is not much smaller than Pluto. The center of mass of the Pluto/Charon system is actually outside of Pluto. And Pluto and Charon both orbit around this point, both with orbital periods of about 6.5 Earth days. Pluto and Charon are also in a mutual gravitational tidal lock, hence they both keep the same side facing the other.

 

The Mordor and the Tallest Cliff in the Solar System

Two features on Charon’s surface immediately jump out at you. First, its north pole is dark red due to a dusting of complex organics, similar to Pluto. Once methane is on Charon, sunlight breaks down the methane to create the same complex organics at Charon’s north pole, just like on Pluto itself. This area on Charon has been informally named Mordor, from the Dark Lord Sauron’s home in J. R. R. Tolkien’s Lord of the Rings. We find a series of canyons or chasmata in Charon’s equatorial region. These are all named for vessels in fiction. For example, Serenity Chasma is named for the spaceship in the Firefly series, and Nostromo is named for the spaceship in the Alien films. Argo Chasma, named after the mythological ship of Jason and the Argonauts, can be as deep as 9 kilometers. The cliffs surrounding it put Argo in the running for the tallest cliff in the solar system. The only other contender is Miranda’s Verona Rupes in the Uranus system, where estimates range between 5 and 20 kilometers. New Horizons had an excellent position for looking directly into sheer cliffs that seem to be several miles deep. The full length of Argo Chasma is longer than the Grand Canyon, and it’s 5 times deeper.

 

The Other Moons of Pluto

The binary system of Pluto and Charon is itself orbited by a system of four other moons, all very small. These small moons are all non-spherical, with longest dimensions of only tens of kilometers across. Nix and Hydra are about twice the radius of Mars’s larger moon, Phobos. Styx and Kerberos are closer in size to Mars’s smaller moon, Deimos. Styx is about twice as far from Pluto as Charon and takes around 20 days to complete one orbit. Styx is only about 7 kilometers in its longest dimension. Next out is Nix, whose longest dimension is about 50 kilometers. We have a bit better of an image of Nix from the New Horizons mission than we have of the other 3 moons, and it reveals several impact craters on the surface. Kerberos is about 3 times farther from Pluto than Charon and has the longest dimension of about 12 kilometers. Finally, there is Hydra, the outermost moon, at about 4 times Charon’s distance from Pluto. It’s also the biggest of these small moons with a long dimension of about 51 kilometers.

 

Interestingly, despite all the chaos in the direction of the spin poles, all of Pluto’s moons do orbit in its equatorial plane in the prograde direction on circular orbits. This suggests that the moons formed around Pluto, rather than being captured. One possible explanation is that all five of Pluto’s moons, including Charon, are the result of a giant collision, similar to the impact that created the Earth-Moon system.

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Race for monkeypox vaccines, experts fear a repeat of COVID situation

Race for monkeypox vaccines, experts fear a repeat of COVID situation | Amazing Science | Scoop.it

Moves by rich countries to buy large quantities of monkeypox vaccine, while declining to share doses with Africa, could leave millions of people unprotected against a more dangerous version of the disease and risk continued spillovers of the virus into humans, public health officials are warning. Critics fear a repeat of the catastrophic inequity problems seen during the coronavirus pandemic.

 

“The mistakes we saw during the COVID-19 pandemic are already being repeated,” said Dr. Boghuma Kabisen Titanji, an assistant professor of medicine at Emory University. While rich countries have ordered millions of vaccines to stop monkeypox within their borders, none have announced plans to share doses with Africa, where a more lethal form of monkeypox is spreading than in the West.

 

To date, there have been more than 22,000 monkeypox cases reported in nearly 80 countries since May, with about 75 suspected deaths in Africa, mostly in Nigeria and Congo. On Friday, Brazil and Spain reported deaths linked to monkeypox, the first reported outside Africa. Spain reported a second monkeypox death Saturday. “The African countries dealing with monkeypox outbreaks for decades have been relegated to a footnote in conversations about the global response,” Titanji said.

 

Scientists say that, unlike campaigns to stop COVID-19, mass vaccinations against monkeypox won’t be necessary. They think targeted use of the available doses, along with other measures, could shut down the expanding epidemics that were recently designated by the World Health Organization as a global health emergency. Yet while monkeypox is much harder to spread than COVID-19, experts warn if the disease spills over into general populations — currently in Europe and North America it is circulating almost exclusively among gay and bisexual men — the need for vaccines could intensify, especially if the virus becomes entrenched in new regions.

 

Recently, the Africa Centers for Disease Control and Prevention called for the continent to be prioritized for vaccines, saying it was again being left behind. “If we’re not safe, the rest of the world is not safe,” said Africa CDC’s acting director, Ahmed Ogwell. Although monkeypox has been endemic in parts of Africa for decades, it mostly jumps into people from infected wild animals and has not typically spread very far beyond the continent. Experts suspect the monkeypox outbreaks in North America and Europe may have originated in Africa long before the disease started spreading via sex at two raves in Spain and Belgium. Currently, more than 70% of the world’s monkeypox cases are in Europe, and 98% are in men who have sex with men.

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AlphaFold expands AI protein structure prediction database by 200 fold in collaboration with EMBL covering now nearly 200 million structures

AlphaFold expands AI protein structure prediction database by 200 fold in collaboration with EMBL covering now nearly 200 million structures | Amazing Science | Scoop.it
Today, in partnership with EMBL’s European Bioinformatics Institute (EMBL-EBI), we’re now releasing predicted structures for nearly all catalogued proteins known to science, which will expand the AlphaFold DB by over 200x - from nearly 1 million structures to over 200 million structures - with the potential to dramatically increase our understanding of biology.

 

It’s been one year since Deepmind released and open sourced AlphaFold, a sophisticated AI system to predict the 3D structure of a protein just from its 1D amino acid sequence, and created the AlphaFold Protein Structure Database (AlphaFold DB) to freely share this scientific knowledge with the world. Proteins are the building blocks of every life form on earth, they underpin all biological processes in every living thing. And, because a protein’s shape is closely linked with its function, knowing a protein’s structure unlocks a greater understanding of what it does and how it works. Deepmind hoped this groundbreaking resource would help accelerate scientific research and discovery globally, and that other teams could learn from and build on these advances with AlphaFold's AI to create further breakthroughs. That hope has become a reality far quicker than anyone had dared to dream. Just twelve months later, AlphaFold now has been accessed by more than half a million researchers and used to accelerate progress on important real-world problems ranging from plastic pollution to antibiotic resistance.

 

Recently, Deepmind has entered the next stage of this journey. In partnership with EMBL’s European Bioinformatics Institute (EMBL-EBI), they are now releasing predicted structures for nearly all cataloged proteins known to science, which will expand the AlphaFold DB  by over 200 fold - from nearly 1 million structures to over 200 million structures - with the potential to dramatically increase our understanding of biology.

 

This update includes predicted structures for plants, bacteria, animals, and other organisms, opening up many new opportunities for researchers to use AlphaFold to advance their work on important issues, including sustainability, food insecurity, and neglected diseases.The recent update means that most pages on the main protein database UniProt will come with a predicted structure. All 200+ million structures will also be available for bulk download via Google Cloud Public Datasets, making AlphaFold even more accessible to scientists around the world.

 

"AlphaFold is the singular and momentous advance in life science that demonstrates the power of AI. Determining the 3D structure of a protein used to take many months or years, it now takes seconds. AlphaFold has already accelerated and enabled massive discoveries, including cracking the structure of the nuclear pore complex. And with this new addition of structures illuminating nearly the entire protein universe, we can expect more biological mysteries to be solved each day" states Eric Topol, Founder and Director of the Scripps Research Translational Institute in La Jolla, California.

 

AlphaFold’s impact so far

Twelve months on from AlphaFold’s initial release, it’s been amazing to reflect on the incredible impact AlphaFold has already had, and our long journey to reach today’s milestone. For Deepmind's team, AlphaFold’s success was especially rewarding, both because it was the most complex AI system they had ever built, requiring multiple critical innovations, and because it has had the most meaningful downstream impact. By demonstrating that AI could accurately predict the shape of proteins down to atomic accuracy, at scale and in minutes for most proteins, AlphaFold not only provided a solution to a 50-year grand challenge, it also became the first big proof point of our founding thesis: that artificial intelligence can dramatically accelerate scientific discovery, and in turn advance humanity.

 

Deepmind open sourced AlphaFold’s code and published two in-depth papers in the Nature magazine, which have already been cited more than 4,000 times. The Deepmind team collaborated closely with the world-leading EMBL-EBI to design a tool that would best help biologists access and use AlphaFold, and together released the AlphaFold DB, a searchable database that is open and free to all. Before releasing AlphaFold, in line with their careful approach to pioneering responsibly, Deepmind sought input from more than 30 experts across biology research, security, ethics and safety to help to understand how to share the benefits of AlphaFold with the world, in a way that would maximize potential benefit and minimize potential risks.

 

To date, more than 500,000 researchers from 190 countries have accessed the AlphaFold DB to view over 2 million structures. Alphafold's freely available structures have also been integrated into other public datasets, such as Ensembl, UniProt, and OpenTargets, where millions of users access them as part of their everyday workflows.

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Physicists discover a “family” of robust, superconducting graphene structures

Physicists discover a “family” of robust, superconducting graphene structures | Amazing Science | Scoop.it
MIT physicsts identified new multilayered configurations of graphene that can be twisted and stacked to elicit robust superconductivity at low temperatures. The study establishes these configurations as the first known “family” of multilayer magic-angle superconductors.

 

When it comes to graphene, it appears that superconductivity runs in the family. Graphene is a single-atom-thin material that can be exfoliated from the same graphite that is found in pencil lead. The ultrathin material is made entirely from carbon atoms that are arranged in a simple hexagonal pattern, similar to that of chicken wire.

 

Since its isolation in 2004, graphene has been found to embody numerous remarkable properties in its single-layer form. In 2018, MIT researchers found that if two graphene layers are stacked at a very specific “magic” angle, the twisted bilayer structure could exhibit robust superconductivity, a widely sought material state in which an electrical current can flow through with zero energy loss. Recently, the same group found a similar superconductive state exists in twisted trilayer graphene — a structure made from three graphene layers stacked at a precise, new magic angle.

 

Now the team reports that — you guessed it — four and five graphene layers can be twisted and stacked at new magic angles to elicit robust superconductivity at low temperatures. This latest discovery, published this week in Nature Materials,  establishes the various twisted and stacked configurations of graphene as the first known “family” of multilayer magic-angle superconductors. The team also identified similarities and differences between graphene family members.

 

The findings could serve as a blueprint for designing practical, room-temperature superconductors. If the properties among family members could be replicated in other, naturally conductive materials, they could be harnessed, for instance, to deliver electricity without dissipation or build magnetically levitating trains that run without friction.

 

“The magic-angle graphene system is now a legitimate ‘family,’ beyond a couple of systems,” says lead author Jeong Min (Jane) Park, a graduate student in MIT’s Department of Physics. “Having this family is particularly meaningful because it provides a way to design robust superconductors.”

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Heaviest neutron star to date is a ‘black widow’ eating its companion star

Heaviest neutron star to date is a ‘black widow’ eating its companion star | Amazing Science | Scoop.it

Millisecond pulsars spin far more rapidly than expected for a collapsed star. The best chance to study these neutron stars is to find a black widow system where the pulsar has evaporated and eaten much of its companion star. The Keck I telescope was just able to capture spectra of one such companion, allowing astronomers to weigh its pulsar. It's the heaviest found to date, and perhaps near the upper limit for a neutron star.

 

A dense, collapsed star spinning 707 times per second -- making it one of the fastest spinning neutron stars in the Milky Way galaxy -- has shredded and consumed nearly the entire mass of its stellar companion and, in the process, grown into the heaviest neutron star observed to date. Weighing this record-setting neutron star, which tops the charts at 2.35 times the mass of the sun, helps astronomers understand the weird quantum state of matter inside these dense objects, which -- if they get much heavier than that -- collapse entirely and disappear as a black hole.

 

"We know roughly how matter behaves at nuclear densities, like in the nucleus of a uranium atom," said Alex Filippenko, Distinguished Professor of Astronomy at the University of California, Berkeley. "A neutron star is like one giant nucleus, but when you have one-and-a-half solar masses of this stuff, which is about 500,000 Earth masses of nuclei all clinging together, it's not at all clear how they will behave."

 

Roger W. Romani, professor of astrophysics at Stanford University, noted that neutron stars are so dense -- 1 cubic inch weighs over 10 billion tons -- that their cores are the densest matter in the universe short of black holes, which because they are hidden behind their event horizon are impossible to study. The neutron star, a pulsar designated PSR J0952-0607, is thus the densest object within sight of Earth.

 

The measurement of the neutron star's mass was possible thanks to the extreme sensitivity of the 10-meter Keck I telescope on Maunakea in Hawai'i, which was just able to record a spectrum of visible light from the hotly glowing companion star, now reduced to the size of a large gaseous planet. The stars are about 3,000 light years from Earth in the direction of the constellation Sextans.

Discovered in 2017, PSR J0952-0607 is referred to as a "black widow" pulsar -- an analogy to the tendency of female black widow spiders to consume the much smaller male after mating.

 

Filippenko and Romani have been studying black widow systems for more than a decade, hoping to establish the upper limit on how large neutron stars/pulsars can grow. "By combining this measurement with those of several other black widows, we show that neutron stars must reach at least this mass, 2.35 plus or minus 0.17 solar masses," said Romani, who is a professor of physics in Stanford's School of Humanities and Sciences and member of the Kavli Institute for Particle Astrophysics and Cosmology. "In turn, this provides some of the strongest constraints on the property of matter at several times the density seen in atomic nuclei. Indeed, many otherwise popular models of dense-matter physics are excluded by this result."

 

If 2.35 solar masses is close to the upper limit of neutron stars, the researchers say, then the interior is likely to be a soup of neutrons as well as up and down quarks -- the constituents of normal protons and neutrons -- but not exotic matter, such as "strange" quarks or kaons, which are particles that contain a strange quark.

"A high maximum mass for neutron stars suggests that it is a mixture of nuclei and their dissolved up and down quarks all the way to the core," Romani said. "This excludes many proposed states of matter, especially those with exotic interior composition."

Romani, Filippenko and Stanford graduate student Dinesh Kandel are co-authors of a paper describing the team's results that has been accepted for publication by The Astrophysical Journal Letters.

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Marmosets monkeys practice calling their mother in the womb

Marmosets monkeys practice calling their mother in the womb | Amazing Science | Scoop.it

Baby marmosets begin practicing the face and mouth movements necessary to call their family for help before they are born, shows a study published today in eLife. This finding may also apply to humans, as ultrasounds in the third trimester of pregnancy have shown developing humans in the womb making crying-like movements.

 

The first cries and coos of humans and other primates are essential to their survival. In addition to allowing them to call their family members for help, these vocalizations and interactions with their parents and other caregivers lay the groundwork for more complex communication later in life. "We wanted to know how those very first neonatal vocalizations develop," says lead author Darshana Narayanan, who conducted the study as a graduate student at the Department of Psychology and the Princeton Neuroscience Institute, Princeton University, New Jersey, US.

 

Narayanan and colleagues conducted ultrasounds two to three times per week in four pregnant marmosets for a total of 14-17 ultrasound sessions per marmoset, starting when the face first became visible on ultrasound and ending the day before birth. The team used the ultrasound scans to longitudinally track the head, face and mouth movements of the developing marmosets and compared them with the newborn marmosets' movements when they called out. Using frame-by-frame analysis, the team found that the developing marmosets' head and mouth movements coordinated initially, but the mouth movement became distinct over time. Eventually, they became almost indistinguishable from movements made by crying newborn marmosets briefly separated from their mothers within the first 24 hours after birth.

 

To verify that these movements were not generic head and mouth movements, the team also compared pre and postnatal licking movements and movements associated with another marmoset vocalization called a "twitter." Their results showed that the pattern of crying movements before and following birth was distinct from the licking or twitter movements. "Our experiments show that marmosets begin practicing the movements needed for important social calls even before they can generate a sound," Narayanan says. She adds that studying these movements further in marmosets may help scientists learn more about the development of social vocalizations in other primates, including humans.

"Marmoset monkeys offer a special opportunity to study primate vocal development," concludes senior author Asif Ghazanfar, Professor at the Princeton Neuroscience Institute, Princeton University. "Like humans, marmosets are very social and learn to vocalize through interactions with their parents."

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Chemists Believe They Have Cracked The Complete Quantum Nature of Water Using AI

Chemists Believe They Have Cracked The Complete Quantum Nature of Water Using AI | Amazing Science | Scoop.it

Chemists have produced the first full quantum mechanical model of water — one of the key ingredients of life. The Journal of Physical Chemistry Letters published the breakthrough, which used machine learning to develop a model that gives a detailed, accurate description for how large groups of water molecules interact with one another. “We believe we have found the missing piece to a complete, microscopic understanding of water,” says Joel Bowman, professor of theoretical chemistry at Emory University and senior author of the study. “It appears that we now have all that we need to know to describe water molecules under any conditions, including ice, liquid or vapor over a range of temperature and pressure.”

 

The researchers developed free, open-source software for the model, which they dubbed “q-AQUA.”  The q-AQUA software provides a universal tool for studying water. “We anticipate researchers using it for everything from predicting whether an exoplanet may have water to deepening our understanding of the role of water in cellular function,” Bowman says.

 

Bowman is one of the founders of the specialty of theoretical reaction dynamics and a leader in exploring mysteries underlying questions such as why we need water to live. First author of the study is Qi Yu, a former Emory PhD candidate in the Bowman Lab who has since graduated and is now a postdoctoral fellow at Yale. Co-authors include Emory graduate student Apurba Nandi, a PhD candidate in the Bowman Lab; Riccardo Cone, a former Emory postdoctoral fellow in the Bowman Lab, who is now at the University of Milan; and Paul Houston, former dean of science at Georgia Institute of Technology and now an emeritus professor at Cornell University.

The discovery made the cover of the Journal of Physical Chemistry Letters.

 

Water covers most of the Earth’s surface and is vital to all living organisms. It consists of simple molecules, each made up of two hydrogen atoms and one oxygen atom, bound by hydrogen.

Despite water’s simplicity and ubiquity, describing the interactions of clusters of H2O molecules under any conditions presents major challenges. Newton’s law governs the behavior of heavy objects in the so-called classical world, including the motion of planets. Extremely light objects, however, at the level of atoms and electrons, are part of the quantum world which is governed by the Schrodinger equation of quantum-mechanical systems.

 

Each water molecule consists of a single oxygen atom and two hydrogen atoms. “We’re about 70% water by weight,” Bowman says, “and yet, from a chemical standpoint, we don’t really understand how water molecules interact with biological systems."

 

Although large, complex problems in the classical world can be divided into pieces to be solved, objects in the quantum world are too “fuzzy” to be broken down into discrete pieces. Researchers have tried to produce a quantum model of water by breaking it into the interactions of clusters of water molecules. Bowman compares it to people at a party clustered into conversational groups of two, three or four people.

 

“Imagine you’re trying to come up with a model to describe the conversations in each of these clusters of people that can be extended to the entire party,” he says. “First you gather the data for two people talking and determine what they are saying, who is saying what and what the conversation means. It gets harder when you try to model the conversations among three people. And when you get up to four people, it gets nearly impossible because so much data is coming at you.”

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Moths use ultrasound to defend against bats and other predators

Moths use ultrasound to defend against bats and other predators | Amazing Science | Scoop.it

In a new study published in the journal PNAS, researchers found that there are more species of moths that produce sounds to fend off predators, such as bats, at night. They also discovered three new sound-producing organs in moths than previously thought.

 
 

“It’s not just tiger moths and hawk moths that are doing this. There are tons of moths that create ultrasonic sounds, and we hardly know anything about them,” said Senior Author Akito Kawahara, a curator at the Florida Museum of Natural History’s McGuire Center for Lepidoptera & Biodiversity.

 

The researchers also compared how these sounds converge between different moth species. They noted that moth species that lack natural defense sounds can mimic the pitch and timber of their relatives. This ability makes the number of moths with sound mimicry capacity larger than thought before.

 

The research has been ongoing for over a decade, with data collected from Ecuador, Mozambique, French Guiana and Malaysia Borneo. The data was then analyzed with the help of theoretical physicists and machine learning. The researchers scrutinized each sound not to find similarities and differences.

 

“Moths and butterflies are collectively one of the most diverse groups on the planet, containing one of every 10 named animals. If these results pan out, it will likely be the largest set of mimicry complexes on Earth,” said Professor of Biology Jesse Barber at the Boise State University. Moreover, the mimicry observed goes beyond the moth species. Most of the insects under study were found to produce some kind of sound that could be mimicked.  “These mimicry complexes are likely not just limited to moths,” Kawahara said. “The whole tapestry of nocturnal insect life is probably involved, but the chance to understand the natural world is going away. So many lineages are going extinct that we’re likely in the last golden age of biology.”

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