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The mucus and hairs in your nose can trap larger particles, and the mucus and cilia in your upper airway can catch some as well, said Luke Montrose, an environmental toxicologist at Colorado State University. But some PM2.5 or smaller particles can bypass these defenses and penetrate the deepest parts of your lungs. Dr. Montrose […] More
When Shawn Connolly was diagnosed with Parkinson’s disease nine years ago, he was a 39-year-old daredevil on a skateboard, flipping and leaping from walls, benches and dumpsters through the streets of San Francisco. He appeared in videos and magazines, and had sponsorships from skateboard makers and shops.But gradually, he began to notice that “things weren’t really working right” with his body. He found that his right hand was cupping, and he began cradling his arm to hold it in place. His balance and alignment started to seem off.Over time, he developed a common Parkinson’s pattern, fluctuating between periods of rapid involuntary movements like “I’ve got ants in my pants” and periods of calcified slowness when, he said, “I could barely move.”A couple of years ago, Mr. Connolly volunteered for an experiment that summoned his daring and determination in a different way. He became a participant in a study exploring an innovative approach to deep brain stimulation.In the study, which was published Monday in the journal Nature Medicine, researchers transformed deep brain stimulation — an established treatment for Parkinson’s — into a personalized therapy that tailored the amount of electrical stimulation to each patient’s individual symptoms.The researchers found that for Mr. Connolly and the three other participants, the individualized approach, called adaptive deep brain stimulation, cut in half the time they experienced their most bothersome symptom.We are having trouble retrieving the article content.Please enable JavaScript in your browser settings.Thank you for your patience while we verify access. If you are in Reader mode please exit and log into your Times account, or subscribe for all of The Times.Thank you for your patience while we verify access.Already a subscriber? Log in.Want all of The Times? Subscribe. More
A biomedical researcher, he found that normal cells can divide only a certain number of times before they age — which, he said, explained aging on a cellular level.Leonard Hayflick, a biomedical researcher who discovered that normal cells can divide only a certain number of times — setting a limit on the human life span and frustrating would-be-immortalists everywhere — died on Aug. 1 at his home in Sea Ranch, Calif. He was 96.His son, Joel Hayflick, said the cause was pancreatic cancer.Like many great scientific findings, Dr. Hayflick’s came somewhat by accident. As a young scientist in the early 1960s at the Wistar Institute, a research organization at the University of Pennsylvania, he was trying to develop healthy embryonic cell lines in order to study whether viruses can cause certain types of cancer.He and a colleague, Paul Moorhead, soon noticed that somatic — that is, nonreproductive — cells went through a phase of division, splitting between 40 and 60 times, before lapsing into what he called senescence.As senescent cells accumulate, he posited, the body itself begins to age and decline. The only cells that do not go into senescence, he added, are cancer cells.As a result of this cellular clock, he said, no amount of diet or exercise or genetic tweaking will push the human species past a life span of about 125 years.This finding, which the Nobel-winning virologist Macfarlane Burnet later called the Hayflick limit, ran counter to everything scientists believed about cells and aging — especially the thesis that cells themselves are immortal, and that aging is a result of external causes, like disease, diet and solar radiation.We are having trouble retrieving the article content.Please enable JavaScript in your browser settings.Thank you for your patience while we verify access. If you are in Reader mode please exit and log into your Times account, or subscribe for all of The Times.Thank you for your patience while we verify access.Already a subscriber? Log in.Want all of The Times? Subscribe. More
Specimens of what appear to be the largest eurypterid species found in Australia could shed light on the sudden extinction of the massive arthropods.Most modern scorpions would fit in the palm of your hand. But in the oceans of the Paleozoic era more than 400 million years ago, animals known popularly as sea scorpions were apex predators that could grow larger than people in size.“They were effectively functioning as sharks,” said Russell Bicknell, a paleobiologist at the American Museum of Natural History.New research by Dr. Bicknell and colleagues, published Saturday in the journal Gondwana Research and relying on Australian fossils, reveals that the biggest sea scorpions were capable of crossing oceans, a finding that is “absolutely pushing the limits of what we know arthropods could do,” he said.What are commonly known as sea scorpions were a diverse group of arthropods called eurypterids. They came in many shapes and sizes but are perhaps best known for their largest representatives, which could grow to more than nine feet long. With huge claws, a beefy exoskeleton and a strong set of legs for swimming, the larger sea scorpions most likely ruled the seas.However fearsome these arthropods must have been to Paleozoic prey, they went extinct without much of a bang. The fossil record of eurypterids peaked in the Silurian period, which started about 444 million years ago, and they then abruptly died out after the early Devonian period ended about 393 million years ago.That sudden turn of fate has left scientists bewildered.“They appear, they start doing really well, they get very big, and then they go extinct,” said James Lamsdell, a paleobiologist at West Virginia University who was not involved in the study. “For a while they were so dominant, and then they just burned out.”We are having trouble retrieving the article content.Please enable JavaScript in your browser settings.Thank you for your patience while we verify access. If you are in Reader mode please exit and log into your Times account, or subscribe for all of The Times.Thank you for your patience while we verify access.Already a subscriber? Log in.Want all of The Times? Subscribe. More
These forests below the Arctic Circle are designed to burn. A camera slowly rises above a large forest of light green trees extending to the horizon. But not this often. A camera slowly rises above a similar landscape, but the forest from this vantage point is burned. The dead black spruce looked like a collection […] More
A new study shows that behavioral and social changes can reduce heat mortality. But challenges remain as temperatures continue to rise.More than 47,000 Europeans died from heat-related causes during 2023, the world’s hottest year on record, a new report in Nature Medicine has found.But the number could have been much higher.Without adaptations to rising temperatures over the past two decades — including advances in health care, more widespread air-conditioning and improved public information that kept people indoors and hydrated during extreme temperatures — the death toll for Europeans experiencing the same temperatures at the start of the 21st century could have been 80 percent higher, according to the new study. For people over 80 years old, the death toll could have doubled.“We need to consider climate change as a health issue,” said Elisa Gallo, a postdoctoral researcher at the Barcelona Institute for Global Health, a nonprofit research center, and the lead author of the study. “We still have thousands of deaths caused by heat every year, so we still have to work a lot and we have to work faster.”Counting deaths from extreme heat is difficult, in part because death certificates don’t always reflect the role heat played in a person’s death. The study used publicly available death records in 35 countries, representing about 543 million Europeans and provided by Eurostat, the statistics office of the European Union.The researchers used an epidemiological model to analyze the deaths alongside 2023 weekly temperature records to estimate what fraction of deaths could be attributable to heat.We are having trouble retrieving the article content.Please enable JavaScript in your browser settings.Thank you for your patience while we verify access. If you are in Reader mode please exit and log into your Times account, or subscribe for all of The Times.Thank you for your patience while we verify access.Already a subscriber? Log in.Want all of The Times? Subscribe. More
Scholars have struggled to identify fragments of the epic of Gilgamesh — one of the world’s oldest literary texts. Now A.I. has brought an “extreme acceleration” to the field.In 1872, in a quiet second-floor room at the British Museum, George Smith, a museum employee, was studying a grime-encrusted clay tablet when he came across words that would change his life. In the ancient cuneiform script, he recognized references to a stranded ship and a bird sent in search of land. After he had the tablet cleaned, Smith was certain he’d found a prototype of the biblical flood story.“I am the first man to read that after more than 2,000 years of oblivion,” Smith reportedly said in a frenzy of excitement.Smith realized that the tablet, which had been excavated in what is modern-day Iraq, was a small part of a much longer work — one that some then thought could help shed light on the Book of Genesis. The discovery made Smith, who came from a working-class family and had largely taught himself cuneiform, famous. He dedicated the rest of his life to searching for missing pieces of the poem, making multiple trips to the Middle East before dying of an illness on his final trip in 1876, at age 36.For 152 years since Smith’s discovery, successive generations of Assyriologists — experts in the study of cuneiform and the cultures that used it — have taken up his quest to piece together a complete version of the poem known now as the Epic of Gilgamesh. Fragments of the epic, which was written more than 3,000 years ago and was based upon still earlier works, have re-emerged as tablets have been unearthed in archaeological digs, found in museum store rooms or surfaced on the black market.The researchers face a daunting task. There are as many as half a million clay tablets housed in the Mesopotamian collections of various world museums and universities, along with many more tablet fragments. But since there are so few experts in cuneiform, many of these writings are unread and many more are unpublished.So despite a generation-spanning effort, about 30 percent of Gilgamesh remains missing and there are gaps in modern understanding both of the poem and Mesopotamian writing in general.We are having trouble retrieving the article content.Please enable JavaScript in your browser settings.Thank you for your patience while we verify access. If you are in Reader mode please exit and log into your Times account, or subscribe for all of The Times.Thank you for your patience while we verify access.Already a subscriber? Log in.Want all of The Times? Subscribe. More
The journal Psychopharmacology has retracted three papers about MDMA-assisted therapy based on what the publication said was unethical conduct at one of the study sites where the research took place.Several of the papers’ authors are affiliated with Lykos Therapeutics, the drug company whose application for MDMA-assisted therapy to treat post-traumatic stress disorder was rejected last week by the Food and Drug Administration. The company said the research in the retracted papers was not part of its application to the F.D.A. In declining to approve Lykos’s application, the agency cited concerns about missing data and problems with the way the company’s study was designed, according to a statement released by Lykos on Friday.The F.D.A. has asked Lykos to conduct an additional clinical trial of its MDMA-assisted therapy, which would have been the first psychedelic medicine to win approval by federal regulators. Lykos has said it would appeal the decision.The journal retraction was first reported by Stat, the health and medical news website.On Sunday, Lykos said that it disagreed with Psychopharmacology’s decision and that it would file an official complaint with the Committee on Publication Ethics, a nonprofit that sets guidelines for academic publications.“The articles remain scientifically sound and present important contributions to the study of potential treatments for PTSD,” the company said in the statement.The incident cited by Psychopharmacology has been well documented. In 2015, an unlicensed Canadian therapist who took part in the trial engaged in a sexual relationship with a participant after the conclusion of the trial’s dosing sessionsIn civil court documents, the patient, Meaghan Buisson, said she was sexually assaulted by the therapist, Richard Yensen, who at the time was working alongside his wife, a licensed therapist. Mr. Yensen has said the relationship was consensual and initiated by Ms. Buisson. Six months after the final session, she moved from Vancouver to Cortes Island, in British Columbia, where the couple lived, according to court documents. The relationship between patient and practitioner continued for more than a year, the documents said. Professional associations in both Canada and the United States prohibit sexual relationships between psychologists and patients for at least two years after their final session. The incident helped highlight some of the challenges associated with psychedelic medicine, which can render patients especially vulnerable during dosing sessions. For that reason, most clinical trials involving psychedelic compounds require the presence of two mental health professionals. (Lykos’s trials with MDMA require only one of the practitioners to be licensed.)The Multidisciplinary Association for Psychedelic Studies, or MAPS, is the nonprofit that carried out the research and later created Lykos to market its proprietary MDMA-assisted therapy. The association publicly acknowledged the incident in 2019, adding that it had been reported to the F.D.A. and to Canadian health authorities.The company acknowledged on Sunday that it had failed to notify Psychopharmacology about the violations, but it said that the oversight should have been addressed through a correction, not a retraction. More
