© Kang-Chun Cheng for The New York Times
New schizophrenia cases linked to cannabis use disorder more than doubled in Ontario after legalisation of drug
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Senescent cells power the body’s ageing process, and scientists are developing treatments to annihilate them
At St Jude children’s research hospital in Memphis, Tennessee, an unusual clinical trial is under way that, if successful, could have wider ramifications for the vast field of age-related chronic diseases. At first glance, childhood cancer survivors may seem like an unusual population in which to study ageing, but as Greg Armstrong, principal investigator of St Jude’s Childhood Cancer Survivorship Study, explains, we now know they represent a group of individuals who are ageing unusually quickly.
For while modern chemotherapies and radiotherapies have become increasingly efficient at curing childhood cancers, this comes at a great cost, owing to the corrosive impact of such treatment on these children’s bodies, something that becomes more apparent when they reach middle age.
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© Photograph: Shutterstock AI/Shutterstock
© Photograph: Shutterstock AI/Shutterstock
Developing countries urge biggest polluters to act as Trump’s return to the White House heightens geopolitical turmoil
The vast majority of governments are likely to miss a looming deadline to file vital plans that will determine whether or not the world has a chance of avoiding the worst ravages of climate breakdown.
Despite the urgency of the crisis, the UN is relatively relaxed at the prospect of the missed date. Officials are urging countries instead to take time to work harder on their targets to cut greenhouse gas emissions and divest from fossil fuels.
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© Photograph: AP
© Photograph: AP
An accident left Noland Arbaugh paralysed, but Musk’s Neuralink brain implant allows him to control computers with his thoughts. Is it a life-changing innovation that could help millions – or the start of a dystopia where a billionaire can access our thoughts?
Noland Arbaugh’s life changed in a fraction of a second in June 2016. He was a 22-year-old student, working at a kids’ summer camp in upstate New York, when he went swimming in a lake. He can’t tell me exactly what happened, but thinks one of his friends must have accidentally struck him very hard in the side of his head as they ran into the water and plunged beneath the surface.
When he woke up face down in the water, unable to move or breathe, Noland immediately knew he was paralysed. But he didn’t panic. He felt no fear at all, he says. “You never know what you’re going to do in those high-stress situations. I found out that day that it’s hard to shake me. I am very, very calm under pressure.”
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© Photograph: Steve Craft/The Guardian
© Photograph: Steve Craft/The Guardian
Experts have theorised who owned the treasure which was buried more than a thousand years ago
© National Museums Scotland/PA
The London Underground mosquito been extensively studied as an example of humans driving evolution and emergence of new species
© Wikimedia Commons
Breakthrough brings quantum computing closer to large-scale practical use
© Creative Commons
A sample of asteroid dirt brought back to Earth by NASA’s OSIRIS-REx mission contains amino acids and the nucleobases of RNA and DNA, plus brines that could have facilitated the formation of organic molecules, scanning electron microscopy has shown.
The 120 g of material came from the near-Earth asteroid 101955 Bennu, which OSIRIS-REx visited in 2020. The findings “bolster the hypothesis that asteroids like Bennu could have delivered the raw ingredients to Earth prior to the emergence of life,” Dan Glavin of NASA’s Goddard Space Flight Center tells Physics World.
Bennu has an interesting history. It is 565 m across at its widest point and was once part of a much larger parent body, possibly 100 km in diameter, that was smashed apart in a collision in the Asteroid Belt between 730 million and 1.55 billion years ago. Bennu coalesced from the debris as a rubble pile that found itself in Earth’s vicinity.
The sample from Bennu was parachuted back to Earth in 2023 and shared among teams of researchers. Now two new papers, published in Nature and Nature Astronomy, reveal some of the findings from those teams.
In particular, researchers identified a diverse range of salt minerals, including sodium-bearing phosphates and carbonates that formed brines when liquid water on Bennu’s parent body either evaporated or froze.
The liquid water would have been present on Bennu’s parent during the dawn of the Solar System, in the first few million years after the planets began to form. Heat generated by the radioactive decay of aluminium-26 would have kept pockets of water liquid deep inside Bennu’s parent body. The brines that this liquid water bequeathed would have played a role in kickstarting organic chemistry.
Tim McCoy, of the Smithsonian’s National Museum of Natural History and the lead author of the Nature paper, says that “brines play two important roles”.
One of those roles is producing the minerals that serve as templates for organic molecules. “As an example, brines precipitate phosphates that can serve as a template on which sugars needed for life are formed,” McCoy tells Physics World. The phosphate is like a pegboard with holes, and atoms can use those spaces to arrange themselves into sugar molecules.
The second role that brines can play is to then release the organic molecules that have formed on the minerals back into the brine, where they can combine with other organic molecules to form more complex compounds.
Meanwhile, the study reported in Nature Astronomy, led by Dan Glavin and Jason Dworkin of NASA’s Goddard Space Flight Center, focused on the detection of 14 of the 20 amino acids used by life to build proteins, deepening the mystery of why life only uses “left-handed” amino acids.
Amino acid molecules lack rotational symmetry – think of how, no matter how much you twist or turn your left hand, you will never be able to superimpose it on your right hand. As such, amino acids can randomly be either left- or right-handed, a property known as chirality.
However, for some reason that no one has been able to figure out yet, all life on Earth uses left-handed amino acids.
One hypothesis was that due to some quirk, amino acids formed in space and brought to Earth in impacts had a bias for being left-handed. This possibility now looks unlikely after Glavin and Dworkin’s team discovered that the amino acids in the Bennu sample are a mix of left- and right-handed, with no evidence that one is preferred over the other.
“So far we have not seen any evidence for a preferred chirality,” Glavin says. This goes for both the Bennu sample and a previous sample from the asteroid 162173 Ryugu, collected by Japan’s Hayabusa2 mission, which contained 23 different forms of amino acid. “For now, why life turned left on Earth remains a mystery.”
Another mystery is why the organic chemistry on Bennu’s parent body reached a certain point and then stopped. Why didn’t it form more complex organic molecules, or even life?
Amino acids are the construction blocks of proteins. In turn, proteins are one of the primary molecules for life, facilitating biological processes within cells. Nucleobases have also been identified in the Bennu sample, but although chains of nucleobases are the molecular skeleton of RNA and DNA, neither nucleic acid has been found in an extraterrestrial sample yet.
“Although the wet and salty conditions inside Bennu’s parent body provided an ideal environment for the formation of amino acids and nucleobases, it is not clear yet why more complex organic polymers did not evolve,” says Glavin.
Researchers are still looking for that complex chemistry. McCoy cites the 5-carbon sugar ribose, which is a component of RNA, as an essential organic molecule for life that scientists hope to one day find in an asteroid sample.
“But as you might imagine, as organic molecules increase in complexity, they decrease in number,” says McCoy, explaining that we will need to search ever larger amounts of asteroidal material before we might get lucky and find them.
The answers will ultimately help astrobiologists figure out where life began. Could proteins, RNA or even biological cells have formed in the early Solar System within objects such as Bennu’s parent planetesimal? Or did complex biochemistry begin only on Earth once the base materials had been delivered from space?
“What is becoming very clear is that the basic chemical building blocks of life could have been delivered to Earth, where further chemical evolution could have occurred in a habitable environment, including the origin of life itself,” says Glavin.
What’s really needed are more samples. China’s Tianwen-2 mission is blasting off later this year on a mission to capture a 100 g sample from the small near-earth asteroid 469219 Kamo‘oalewa. The findings are likely to be similar to those of OSIRIS-REx and Hayabusa2, but there’s always the chance that something more complex might be in that sample too. If and when those organic molecules are found, they will have huge repercussions for the origin of life on Earth.
The post Asteroid Bennu contains the stuff of life, sample analysis reveals appeared first on Physics World.
Boston Dynamics vient d’annoncer un partenariat avec le Robotics & AI Institute (RAI Institute) pour améliorer l’apprentissage par renforcement de son robot humanoïde Atlas électrique. Cet institut, fondé en 2022 par Marc Raibert, ancien CEO de Boston Dynamics, est entièrement financé par Hyundai (qui pour rappel a fait …
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