Ce billet a été posté en anglais par Massimo Pigliucci sur le site « Ask a philosopher » le 9 juin 2014. Selon le principe de ce site, un internaute a posé la question « de quelles manières nous pourrions essayer de départager la science et la pseudoscience ». Massimo Pigliucci apporte ici une première réponse. La distinction entre … Lire la suite de [Trad] Démarquer la science de la pseudoscience
Cet billet a été publié en deux parties par le philosophe des sciences Massimo Pigliucci sur son blog Footnotes to Plato le 28 décembre 2018. Partie I Quelle est la place de l’aspect social dans la fabrication de la science ? Si on regarde des manuels scientifiques, on se rend compte que la dimension sociale … Lire la suite de [Trad] Déconstruire la science pour mieux la légitimer
A physicist who shot to fame with claims of the discovery of a room-temperature superconductor engaged in research misconduct, a committee tapped to examine his work has concluded after a monthslong investigation. From a report: Ranga Dias, a physicist at the University of Rochester in New York, has had at least four papers he co-wrote, including three involving superconductivity, retracted in the past 18 months by the journals that published them. A committee of outside experts tapped by the university "identified data-reliability concerns in those papers," a Rochester spokesperson told The Wall Street Journal. "The committee concluded, in accordance with university policy and federal regulations, that Dias engaged in research misconduct," the spokesperson said in an emailed statement.
The work in the papers was funded by the National Science Foundation, the Energy Department, and the Gordon and Betty Moore Foundation, a private organization that funds scientific research. The Moore foundation discontinued its grant late last year, the organization said. Of the $1.6 million award, about $285,000 was spent. The university refunded the rest. The investigation follows three preliminary reviews by the university of one of the studies, published in Nature in 2020 and retracted in 2022 after criticism from other scientists. Those inquiries didn't find enough evidence to prompt a full investigation. Complaints sent to the university in spring 2023 about additional studies prompted a more thorough review. That investigation was completed by March this year, resulting in the misconduct finding. The journal Nature reported earlier this month that this investigation was complete.
For the first time, surgeons have transplanted a kidney from a genetically modified pig into a living person, doctors in Boston said Thursday. From a report: Richard Slayman, 62, of Weymouth, Mass., who is suffering from end-stage kidney disease, received the organ Saturday in a four-hour procedure, Massachusetts General Hospital announced. He is recovering well and is expected to be discharged soon, the hospital said. "I saw it not only as a way to help me, but a way to provide hope for the thousands of people who need a transplant to survive," Slayman said in a statement released by the hospital.
The procedure is the latest development in a fast-moving race to create genetically modified pigs to provide kidneys, livers, hearts and other organs to help alleviate the shortage of organs for people who need transplants. "Our hope is that this transplant approach will offer a lifeline to millions of patients worldwide who are suffering from kidney failure," said Dr. Tatsuo Kawai, the hospital's director for clinical transplant tolerance, in the hospital statement.
Several biotech companies are racing to develop a supply of cloned pigs whose DNA has been genetically modified so they won't be rejected by the human body, spread pig viruses to people or cause other complications. NPR recently got exclusive access to a research farm breeding these animals for a company in this competition, Revivicor Inc. of Blacksburg, Va. The kidney transplanted in Boston came from a pig created by eGenesis of Cambridge, Mass. The eGenesis pigs are bred with 69 genetic modifications to prepare organs for human transplantation. The changes protect against a virus known to infect pigs as well as delete pig genes and add human genes to make the organs compatible with people.
Slashdot reader sciencehabit shared this report from Science magazine:
Nurturing a growing fetus requires a series of profound physical, hormonal, and chemical changes that may rewire every major organ in the body and can cause serious health complications such as hypertension and preeclampsia. But does being pregnant actually take years off your life...?
Today in Cell Metabolism, scientists report that the stress of pregnancy can cause a person's biological age to increase by up to 2 years — a trend that may reverse itself in the months that follow. In some cases, the authors write, those who breastfeed their children after giving birth may end up biologically "younger" than during early pregnancy. The finding represents yet another piece of "compelling" evidence that events during and after pregnancy can have far-reaching health consequences, says Elizabeth Bertone-Johnson, an epidemiologist at the University of Massachusetts Amherst who wasn't involved in the new study...
The discovery that biological aging isn't necessarily a linear process "came as a real surprise," says Kieran O'Donnell, a perinatal researcher at the Yale School of Medicine... But blood samples from 68 participants, collected 3 months after giving birth, revealed a dramatic about-face. Although being pregnant had initially aged their cells between 1 and 2 years, says O'Donnell, their biological age now appeared to be 3 to 8 years younger than it had been during early pregnancy — with different epigenetic clocks algorithms providing slightly bigger or smaller estimates.
Two nights of broken sleep are enough to make people feel years older, according to researchers, who said consistent, restful slumber was a key factor in helping to stave off feeling one's true age. From a report: Psychologists in Sweden found that, on average, volunteers felt more than four years older when they were restricted to only four hours of sleep for two consecutive nights, with some claiming the sleepiness made them feel decades older. The opposite was seen when people were allowed to stay in bed for nine hours, though the effect was more modest, with participants in the study claiming to feel on average three months younger than their real age after ample rest.
"Sleep has a major impact on how old you feel and it's not only your long-term sleep patterns," said Dr Leonie Balter, a psychoneuroimmunologist at the Karolinska Institute in Stockholm and first author on the study. "Even when you only sleep less for two nights that has a real impact on how you feel." Beyond simply feeling more decrepit, the perception of being many years older may affect people's health, Balter said, by encouraging unhealthy eating, reducing physical exercise, and making people less willing to socialise and engage in new experiences.
When a long-term memory forms, some brain cells experience a rush of electrical activity so strong that it snaps their DNA. Then, an inflammatory response kicks in, repairing this damage and helping to cement the memory, a study in mice shows. Nature: The findings, published on 27 March in Nature, are "extremely exciting," says Li-Huei Tsai, a neurobiologist at the Massachusetts Institute of Technology in Cambridge who was not involved in the work. They contribute to the picture that forming memories is a "risky business," she says. Normally, breaks in both strands of the double helix DNA molecule are associated with diseases including cancer. But in this case, the DNA damage-and-repair cycle offers one explanation for how memories might form and last.
It also suggests a tantalizing possibility: this cycle might be faulty in people with neurodegenerative diseases such as Alzheimer's, causing a build-up of errors in a neuron's DNA, says study co-author Jelena Radulovic, a neuroscientist at the Albert Einstein College of Medicine in New York City. [...] To better understand the part these DNA breaks play in memory formation, Radulovic and her colleagues trained mice to associate a small electrical shock with a new environment, so that when the animals were once again put into that environment, they would 'remember' the experience and show signs of fear, such as freezing in place. Then the researchers examined gene activity in neurons in a brain area key to memory -- the hippocampus. They found that some genes responsible for inflammation were active in a set of neurons four days after training. Three weeks after training, the same genes were much less active.
"Researchers have successfully transformed CO2 into methanol," reports SciTechDaily, "by shining sunlight on single atoms of copper deposited on a light-activated material, a discovery that paves the way for creating new green fuels."
Tara LeMercier, a PhD student who carried out the experimental work at the University of Nottingham, School of Chemistry, said: "We measured the current generated by light and used it as a criterion to judge the quality of the catalyst. Even without copper, the new form of carbon nitride is 44 times more active than traditional carbon nitride. However, to our surprise, the addition of only 1 mg of copper per 1 g of carbon nitride quadrupled this efficiency. Most importantly the selectivity changed from methane, another greenhouse gas, to methanol, a valuable green fuel."
Professor Andrei Khlobystov, School of Chemistry, University of Nottingham, said: "Carbon dioxide valorization holds the key for achieving the net-zero ambition of the UK. It is vitally important to ensure the sustainability of our catalyst materials for this important reaction. A big advantage of the new catalyst is that it consists of sustainable elements — carbon, nitrogen, and copper — all highly abundant on our planet." This invention represents a significant step towards a deep understanding of photocatalytic materials in CO2 conversion. It opens a pathway for creating highly selective and tuneable catalysts where the desired product could be dialed up by controlling the catalyst at the nanoscale.
"The research has been published in the Sustainable Energy & Fuels journal of the Royal Society of Chemistry."
Thanks to long-time Slashdot reader Baron_Yam for sharing the article.
A Chinese scientist who was imprisoned for his role in creating the world's first genetically edited babies says he has returned to his laboratory to work on the treatment of Alzheimer's and other genetic diseases. From a report: In an interview with a Japanese newspaper, He Jiankui said he had resumed research on human embryo genome editing, despite the controversy over the ethics of artificially rewriting genes, which some critics predicted would lead to demand for "designer babies."
"We will use discarded human embryos and comply with both domestic and international rules," He told the Mainichi Shimbun, adding that he had no plans to produce more genome-edited babies. Previously, He had used a tool known as Crispr-Cas9 to rewrite DNA in embryos. In 2019 a court in China sentenced He to three years in prison for violating medical regulations after he claimed the previous year that he had created genetically modified twin sisters, Lulu and Nana, before birth. His experiments sent shockwaves through the medical and scientific world. He was widely condemned for having gone ahead with the risky, ethically contentious and medically unjustified procedure with inadequate consent from the families involved.
The court found that He had forged documents from an ethics review panel that were used to recruit couples for his research. He said he had used a gene-editing procedure known as Crispr-Cas9 to rewrite the DNA in the sisters' embryos -- modifications he claimed would make the children immune to HIV. He has continued to defend his work, despite widespread criticism, saying he was "proud" of having created Lulu and Nana. A third girl was born in 2019 as a result of similar experiments.
Slashdot reader sciencehabit shares this report from Science magazine:
Fifty years ago, famed physicist Stephen Hawking wrote down an equation that predicts that a black hole has entropy, an attribute typically associated with the disordered jumbling of atoms and molecules in materials.
The arguments for black hole entropy were indirect, however, and no one had derived the famous equation from the fundamental definition of entropy — at least not for realistic black holes. Now, one team of theorists claims to have done so, although some experts are skeptical.
Reported in a paper in press at Physical Review Letters, the work would solve a homework problem that some theorists have labored over for decades. "It's good to have it done," says Don Marolf, a gravitational theorist at the University of California, Santa Barbara who was not involved in the research. It "shows us how to move forward, that's great."
Slashdot reader sciencehabit shares this report from Science magazine:
Fifty years ago, famed physicist Stephen Hawking wrote down an equation that predicts that a black hole has entropy, an attribute typically associated with the disordered jumbling of atoms and molecules in materials.
The arguments for black hole entropy were indirect, however, and no one had derived the famous equation from the fundamental definition of entropy — at least not for realistic black holes. Now, one team of theorists claims to have done so, although some experts are skeptical.
Reported in a paper in press at Physical Review Letters, the work would solve a homework problem that some theorists have labored over for decades. "It's good to have it done," says Don Marolf, a gravitational theorist at the University of California, Santa Barbara who was not involved in the research. It "shows us how to move forward, that's great."
Computational scientist and mathematician Avi Wigderson of the Institute for Advanced Study (IAS) in Princeton has won the 2023 A.M. Turing Award. From a report: The prize, which is given annually by the Association for Computing Machinery (ACM) to a computer scientist for their contributions to the field, comes with $1 million thanks to Google. It is named in honor of the British mathematician Alan Turing, who helped develop a theoretical foundation for understanding machine computation. Wigderson is being honored "for foundational contributions to the theory of computation, including reshaping our understanding of the role of randomness in computation and for his decades of intellectual leadership in theoretical computer science." He also won the prestigious Abel Prize in 2021 for his work in theoretical computer science -- the first person to be so doubly honored.
In two recent papers, an international team of scientists describes the first known nitrogen-fixing organelle within a eukaryotic cell, which the researchers are calling a nitroplast. Phys.Org reports: The discovery of the organelle involved a bit of luck and decades of work. In 1998, Jonathan Zehr, a UC Santa Cruz distinguished professor of marine sciences, found a short DNA sequence of what appeared to be from an unknown nitrogen-fixing cyanobacterium in Pacific Ocean seawater. Zehr and colleagues spent years studying the mystery organism, which they called UCYN-A. At the same time, Kyoko Hagino, a paleontologist at Kochi University in Japan, was painstakingly trying to culture a marine alga. It turned out to be the host organism for UCYN-A. It took her over 300 sampling expeditions and more than a decade, but Hagino eventually successfully grew the alga in culture, allowing other researchers to begin studying UCYN-A and its marine alga host together in the lab. For years, the scientists considered UCYN-A an endosymbiont that was closely associated with an alga. But the two recent papers suggest that UCYN-A has co-evolved with its host past symbiosis and now fits criteria for an organelle.
In a paper published in Cell in March 2024, Zehr and colleagues from the Massachusetts Institute of Technology, Institut de Ciencies del Mar in Barcelona and the University of Rhode Island show that the size ratio between UCYN-A and their algal hosts is similar across different species of the marine haptophyte algae Braarudosphaera bigelowii. The researchers use a model to demonstrate that the growth of the host cell and UCYN-A are controlled by the exchange of nutrients. Their metabolisms are linked. This synchronization in growth rates led the researchers to call UCYN-A "organelle-like." "That's exactly what happens with organelles," said Zehr. "If you look at the mitochondria and the chloroplast, it's the same thing: they scale with the cell."
But the scientists did not confidently call UCYN-A an organelle until confirming other lines of evidence. In the cover article of the journal Science, published today, Zehr, Coale, Kendra Turk-Kubo and Wing Kwan Esther Mak from UC Santa Cruz, and collaborators from the University of California, San Francisco, the Lawrence Berkeley National Laboratory, National Taiwan Ocean University, and Kochi University in Japan show that UCYN-A imports proteins from its host cells. "That's one of the hallmarks of something moving from an endosymbiont to an organelle," said Zehr. "They start throwing away pieces of DNA, and their genomes get smaller and smaller, and they start depending on the mother cell for those gene products -- or the protein itself -- to be transported into the cell."
Coale worked on the proteomics for the study. He compared the proteins found within isolated UCYN-A with those found in the entire algal host cell. He found that the host cell makes proteins and labels them with a specific amino acid sequence, which tells the cell to send them to the nitroplast. The nitroplast then imports the proteins and uses them. Coale identified the function of some of the proteins, and they fill gaps in certain pathways within UCYN-A. "It's kind of like this magical jigsaw puzzle that actually fits together and works," said Zehr. In the same paper, researchers from UCSF show that UCYN-A replicates in synchrony with the alga cell and is inherited like other organelles.
Nicola Davis reports via The Guardian: If every day appears to go in a blur, try seeking out new and interesting experiences, researchers have suggested, after finding memorable images appear to dilate time. Researchers have previously found louder experiences seem to last longer, while focusing on the clock also makes time dilate, or drag. Now researchers have discovered the more memorable an image, the more likely a person is to think they have been looking at it for longer than they actually have. Such images were also easier for participants to recall the next day. Prof Martin Wiener, co-author of the study who is based at George Mason University in the U.S., said the findings could help develop improve artificial intelligence that interacts with humans, while they also offer opportunities to tweak our perceptions, given research has previously shown non-invasive brain stimulation can be used to lengthen a perceived interval.
The results from two groups, totaling about 100 people, revealed participants were more likely to think they had been looking at small, highly cluttered scenes -- such a crammed pantry -- for a shorter duration than was the case, whereas the reverse occurred when people viewed large scenes with little clutter, such as the interior of an aircraft hangar. The team also carried out experiments involving 69 participants that found images known from previous work to be more memorable were more likely to be judged as having been shown for longer than was the case. Crucially, the effect seemed to go both ways.
"We also found that the longer the perceived subjective duration of an image, the more likely you were to remember it the next day," said Wiener. When the team carried out an analysis using deep learning models of the visual system, they discovered more memorable images were processed faster. What's more, the processing speed for an image was correlated with how long participants thought they had been looking at it. "Images may be more memorable because they are processed faster and more efficiently in the visual system, and that drives the perception of time," said Wiener. The team suggest time dilation might serve a purpose, enabling us to gather information about the world around us. The findings have been published in the journal Nature Human Behavior.
Noise pollution from traffic stunts growth in baby birds, even while inside the egg, research has found. From a report: Unhatched birds and hatchlings that are exposed to noise from city traffic experience long-term negative effects on their health, growth and reproduction, the study found. "Sound has a much stronger and more direct impact on bird development than we knew before," said Dr Mylene Mariette, a bird communication expert at Deakin University in Australia and a co-author of the study, published in the journal Science. "It would be wise to work more to reduce noise pollution."
A growing body of research has suggested that noise pollution causes stress to birds and makes communication harder for them. But whether birds are already distressed at a young age because they are affected by noise, or by how noise disrupts their environment and parental care, was still unclear. Mariette's team routinely exposed zebra finch eggs for five days to either silence, soothing playbacks of zebra finch songs, or recordings of city traffic noises such as revving motors and cars driving past. They did the same with newborn chicks for about four hours a night for up to 13 nights, without exposing the birds' parents to the sounds.
"For the first time in at least a billion years, two lifeforms have merged into a single organism," reports the Independent:
The process, called primary endosymbiosis, has only happened twice in the history of the Earth, with the first time giving rise to all complex life as we know it through mitochondria. The second time that it happened saw the emergence of plants. Now, an international team of scientists have observed the evolutionary event happening between a species of algae commonly found in the ocean and a bacterium...
The process involves the algae engulfing the bacterium and providing it with nutrients, energy and protection in return for functions that it could not previously perform — in this instance, the ability to "fix" nitrogen from the air. The algae then incorporates the bacterium as an internal organ called an organelle, which becomes vital to the host's ability to function.
The researchers from the U.S. and Japan who made the discovery said it will offer new insights into the process of evolution, while also holding the potential to fundamentally change agriculture. "This system is a new perspective on nitrogen fixation, and it might provide clues into how such an organelle could be engineered into crop plants," said Dr Coale.
Two papers detailing the research were published in the scientific journals Science and Cell.
Thanks to Slashdot reader fjo3 for sharing the news.
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