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      How Does Pregnancy Change the Brain? Clues Are Emerging.

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      As hormones surge, some brain areas shrink in what scientists say may be a fine-tuning that helps mothers bond with and care for their babies.Research is revealing intriguing clues about how pregnancy changes the brain. Studies scanning women’s brains before and after pregnancy have found that certain brain networks, especially those involved in social and emotional processing, shrink during pregnancy, possibly undergoing a fine-tuning process in preparation for parenting. Such changes correspond with surges in pregnancy hormones, especially estrogen, and some last at least two years after childbirth, researchers have found.A new study, published Monday in the journal Nature Neuroscience, adds to the picture by documenting with M.R.I.s brain changes throughout one woman’s pregnancy. It confirms previous results and adds detail, including that white matter fibers showed greater ability to efficiently transmit signals between brain cells, a change that evaporated once the baby was born.“What’s very interesting about this current study is that it provides such a detailed mapping,” said Elseline Hoekzema, a neuroscientist who heads the Pregnancy and the Brain Lab at Amsterdam University Medical Center and has helped lead studies analyzing brain scans of more than 100 women before and after pregnancy.Dr. Hoekzema, who was not involved in the new study, said it showed that along with previously documented “longer-lasting changes in brain structure and function, more subtle, transient changes also occur.”Dr. Ronald Dahl, director of the Institute of Human Development at the University of California, Berkeley, who was not involved in the new study, said the emerging research reflected the key role of hormones in transitions like puberty and pregnancy, guiding neurological shifts in priorities and motivations.“There is that sense that it’s affecting so many of these systems,” he said. The study participant, Elizabeth Chrastil, is a neuroscientist at the University of California, Irvine. She became pregnant in 2019, at 38, after in vitro fertilization. That allowed precise tracking of her pregnancy from the start.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

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      Pollution May Affect the Color of City Birds, Research Shows

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      Recent studies show that certain feather pigments can help neutralize toxic pollution. It means darker, duller birds could have a survival advantage.Some popular city dwellers appear to be losing their colorful allure, and not just the dirty birds.According to a study published this summer in the journal Landscape and Planning that looked at 547 bird species in China, birds that live in cities are duller and darker on average than their rural counterparts. A similar conclusion emerged from an analysis of 59 studies published in March in Biological Reviews: Urban feathers are not as bright, with yellow, orange and red feathers affected most.Often, city birds are covered in grime. But even if you could give them all a good bird bath, chances are their brightness still wouldn’t match that of their country cousins. That’s because of the way pollution, and heavy metals in particular, can interact with melanin, a pigment that makes feathers black, brown and gray.Studies show that melanin can bind to heavy metals like lead. That means toxic chemicals may be more likely to be stored in plumage in darker and duller birds. And that, in turn, can confer a survival advantage.“The more melanin you accumulate, the better able you are to sequester these harmful compounds in feathers,” said Kevin McGraw, a biologist at Michigan State University who studies the colors of animals to understand the costs, benefits and evolution of visual signals.Urban pollution affects avian colors in other ways, too. Research shows that compared with rural plants, city trees store fewer natural pigments called carotenoids, and pollution is the likely reason. Carotenoids are produced by plants, algae and fungi. They’re what makes red peppers red and carrots orange.When leaves are low on these pigments, the effects go up the food chain: Leaf-munching caterpillars become deficient in carotenoids, and so do caterpillar-munching birds.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

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      Time to Say Goodbye to the B.M.I.?

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      The body mass index has long been criticized as a flawed indicator of health. A replacement has been gaining support: the body roundness index.Move over, body mass index. Make room for roundness — to be precise, the body roundness index.The body mass index, or B.M.I., is a ratio of height to weight that has long been used as a medical screening tool. It is one of the most widely used health metrics but also one of the most reviled, because it is used to label people overweight, obese or extremely obese.The classifications have been questioned by athletes like the American Olympic rugby player Ilona Maher, whose B.M.I. of 30 technically puts her on the cusp of obesity. “But alas,” she said on Instagram, addressing online trolls who tried to shame her about her weight, “I’m going to the Olympics and you’re not.”Advocates for overweight individuals and people of color note that the formula was developed nearly 200 years ago and based exclusively on data from men, most of them white, and that it was never intended for medical screening. Even physicians have weighed in on the shortcomings of B.M.I. The American Medical Association warned last year that B.M.I. is an imperfect metric that doesn’t account for racial, ethnic, age, sex and gender diversity. It can’t differentiate between individuals who carry a lot of muscle and those with fat in all the wrong places.“Based on B.M.I., Arnold Schwarzenegger when he was a bodybuilder would have been categorized as obese and needing to lose weight,” said Dr. Wajahat Mehal, director of the Metabolic Health and Weight Loss Program at Yale University.“But as soon as you measured his waist, you’d see, ‘Oh, it’s 32 inches.’”So welcome a new metric: the body roundness index. B.R.I. is just what it sounds like — a measure of how round or circlelike you are, using a formula that takes into account height and waist, but not weight.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

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      Are Some Ultraprocessed Foods Worse Than Others?

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      A new study may offer the biggest clues yet.Name a common condition — heart disease, Type 2 diabetes, cancer, dementia, irritable bowel syndrome — and chances are good that following a diet high in ultraprocessed foods has been linked to it.But the ultraprocessed food category is large and wide-ranging. It makes up an estimated 73 percent of the U.S. food supply, and contains stereotypically “unhealthy” products like sodas, candies and hot dogs as well as seemingly “healthy” ones like whole grain breads, breakfast cereals, flavored yogurts and plant milks.It’s a “hodgepodge of foods,” some of which are likely more harmful than others, said Josiemer Mattei, an associate professor of nutrition at the Harvard T.H. Chan School of Public Health.On Monday, Dr. Mattei and her colleagues published one of the largest and longest studies on ultraprocessed foods and heart health to date. In it, they analyzed the risks of consuming these foods, and teased out the worst offenders.An Overall Risk of Ultraprocessed FoodsThe new study, published in a Lancet journal, included more than 200,000 adults in the United States. They filled out detailed diet questionnaires beginning in the 1980s and early 1990s, and completed them again every two to four years for about 30 years. Most of the participants in the study were white and worked as health professionals. The researchers looked at how the participants’ ultraprocessed food consumption related to their chances of developing cardiovascular disease.After adjusting for risk factors like smoking, family health history, sleep and exercise, the researchers found that those who consumed the most ultraprocessed foods were 11 percent more likely to develop cardiovascular disease and 16 percent more likely to develop coronary heart disease during the study period, compared with those who consumed the least ultraprocessed foods. The highest consumers also had a slightly, but not significantly, elevated risk of stroke.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

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      Eliyahu Rips, Who Claimed to Find Secret Codes in the Torah, Dies at 75

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      His work provided the basis for the worldwide best seller “The Bible Code,” but he later rejected the book as unscientific.It sounds like a headline ripped from a supermarket tabloid: In 1994, three Israeli researchers claimed to have found a secret code embedded in Genesis, the first book of the Old Testament.But this wasn’t junk science. The paper in which they revealed their findings appeared in an esteemed, peer-reviewed journal. And the academic reputations of the three authors — Eliyahu Rips, Yoav Rosenberg and Doron Witztum — were unimpeachable, especially that of Dr. Rips.A math prodigy born to Holocaust survivors in Latvia, he had received his doctorate from, and spent his career at, Hebrew University in Jerusalem, where he became known for his work in a field called geometric group theory.He had also become convinced that statistical tools and newer, more powerful computers that were becoming available in the 1980s could be used to identify hidden meaning within the Bible, and he teamed up with his two partners to discover them. Their biggest finding was the names of 32 Jewish scholars in the text, along with their birth or death dates; several of the scholars had lived thousands of years after Genesis was written.Their results, reported in the journal Statistical Science, set off a tempest in the worlds of biblical scholarship and statistical analysis. In 1997, Michael Drosnin, a journalist, used the team’s tools to write “The Bible Code,” a global best seller that claimed to find not just rabbis’ birthdays but also predictions about world events, including the assassination of Israeli Prime Minister Yitzhak Rabin in 1995, all embedded in the Torah, or the first five books of the Old Testament. (Mr. Drosnin died in 2020.)The book put Dr. Rips in an international spotlight. Magazine and newspaper profiles proliferated; with his Gandalfian white beard and wide-brimmed hat, he seemed to embody the intersection of science and Jewish mysticism.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

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      How Wildfire Smoke Threatens Human Health

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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

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      A Personalized Brain Pacemaker for Parkinson’s

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      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

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      Leonard Hayflick, Who Discovered Why No One Lives Forever, Dies at 96

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      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