Starting this fall, most students at Johns Hopkins' medical school will attend tuition-free thanks to a $1 billion donation from billionaire Mike Bloomberg. From a report: The generous gift is intended to address "twin challenges of declining levels of health and education," Bloomberg said in a letter Monday. The donation will cover the full cost of tuition for medical students from families earning less than $300,000, Bloomberg Industries announced Monday. It will also cover living expenses and other fees for students from families earning up to $175,000.

Currently, nearly two-thirds of medical students at the school qualify for financial aid. Johns Hopkins' medical students graduate with an average student loan debt of about $104,000. The donation will also increase financial aid at some of the university's other graduate schools, including the schools of nursing and public health.

A controversial organ retrieval technique is gaining traction across the U.S., promising to alleviate chronic organ shortages but also sparking intense ethical debates, NPR reports. Normothermic regional perfusion, now used by half of the nation's organ procurement organizations, restores blood flow to organs after cardiac death. Proponents argue it increases viable organ supply and improves transplant outcomes. Critics, however, question whether the procedure blurs the definition of death.

An anonymous reader quotes a report from The Guardian: Air pollution exposure can significantly decrease the chance of a live birth after IVF treatment, according to research that deepens concern about the health impacts of toxic air on fertility. Pollutant exposure has previously been linked to increased miscarriage rates and preterm births, and microscopic soot particles have been shown to travel through the bloodstream into the ovaries and the placenta. The latest work suggests that the impact of pollution begins before conception by disrupting the development of eggs. "We observed that the odds of having a baby after a frozen embryo transfer were more than a third lower for women who were exposed to the highest levels of particulate matter air pollution prior to egg collection, compared with those exposed to the lowest levels," said Dr Sebastian Leathersich, a fertility specialist and gynaecologist from Perth who is due to present the findings on Monday at the European Society of Human Reproduction and Embryology annual meeting in Amsterdam. [...]

The study analyzed fertility treatments in Perth over an eight-year period, including 3,659 frozen embryo transfers from 1,836 patients, and tracked whether outcomes were linked to the levels of fine particulate matter, known as PM10. The overall live birthrate was about 28% per transfer. However, the success rates varied in line with exposure to pollutants in the two weeks leading up to egg collection. The odds of a live birth decreased by 38% when comparing the highest quartile of exposure to the lowest quartile. "These findings suggest that pollution negatively affects the quality of the eggs, not just the early stages of pregnancy, which is a distinction that has not been previously reported," Leathersich said. The team now plan to study cells directly to understand why pollutants have a negative effect. Previous work has shown that the microscopic particles can damage DNA and cause inflammation in tissues. The report notes that the link between air pollution and live birth "was apparent despite excellent overall air quality during the study period, with PM10 and PM2.5 levels exceeding WHO guidelines on just 0.4% and 4.5% of the study days."

It adds: "Australia is one of just seven countries that met the WHO's guidelines in 2023, and this study is the latest to show evidence of harm even at relatively low levels of pollution."

The study has been published in the journal Human Reproduction.

The world has baked for 12 consecutive months in temperatures 1.5C (2.7F) greater than their average before the fossil fuel era, new data shows. Temperatures between July 2023 and June 2024 were the highest on record, scientists found, creating a year-long stretch in which the Earth was 1.64C hotter than in preindustrial times. From a report: The findings do not mean world leaders have already failed to honour their promises to stop the planet heating 1.5C by the end of the century -- a target that is measured in decadal averages rather than single years -- but that scorching heat will have exposed more people to violent weather. A sustained rise in temperatures above this level also increases the risk of uncertain but catastrophic tipping points.

Carlo Buontempo, director of the Copernicus Climate Change Service, which analysed the data, said the results were not a statistical oddity but a "large and continuing shift" in the climate. "Even if this specific streak of extremes ends at some point, we are bound to see new records being broken as the climate continues to warm," he said. "This is inevitable unless we stop adding greenhouse gases into the atmosphere and the oceans." Copernicus, a scientific organisation that belongs to the EU's space programme, uses billions of measurements from satellites, ships, aircraft and weather stations to track key climate metrics. It found June 2024 was hotter than any other June on record and was the 12th month in a row with temperatures 1.5C greater than their average between 1850 and 1900. Because temperatures in some months had "relatively small margins" above 1.5C, the scientists said, datasets from other climate agencies may not confirm the 12-month temperature streak.

A Wall Street Journal analysis has revealed that private insurers in the government's Medicare Advantage program, including UnitedHealth Group, have made numerous questionable diagnoses leading to increased taxpayer-funded payments between 2018 and 2021.

The investigation found instances where patients were diagnosed with conditions they did not have, such as diabetic cataracts and HIV, often without their knowledge. These diagnoses resulted in higher payments from Medicare to the insurers. The Centers for Medicare and Medicaid Services said they are implementing changes to ensure "taxpayer dollars are appropriately spent." The story adds: In all, Medicare paid insurers about $50 billion for diagnoses added just by insurers in the three years ending in 2021, the Journal's analysis showed.

"Russia has finally admitted that American astronauts did, in fact, land on the moon," reports Newsweek: Head of Russian Space Corporation Roscosmos, Yuri Borisov, accepted the truth of the U.S. putting a man on the moon in an address to the State Duma, Intellinews has reported.

"As for whether the Americans were on the Moon or not, I have one fact to share," he was reported to have said. "I was personally interested in this matter. At one time, they provided us with a portion of the lunar soil that the astronauts brought back during their expedition." Previous polling revealed that just under half of Russians believe America's 1969 moon landing was a government hoax. However, Borisov said that tests performed on the samples by the Russian Academy of Scientists confirmed their authenticity.

They lived 378 days in a "mock Mars habitat" in Houston, reports Engadget. But today the four volunteers for NASA's yearlong simulation will finally emerge from their 1,700-square-foot habitat at the Johnson Space Center that was 3D-printed from materials that could be created with Martian soil.

And you can watch the "welcome home" ceremony's livestream starting at 5 p.m. EST on NASA TV (also embedded in Engadget's story). More det ails from NASA: For more than a year, the crew simulated Mars mission operations, including "Marswalks," grew and harvested several vegetables to supplement their shelf-stable food, maintained their equipment and habitat, and operated under additional stressors a Mars crew will experience, including communication delays with Earth, resource limitations, and isolation.
One of the mission's crew members told the Houston Chronicle they were "very excited to go back to 'Earth,' but of course there is a bittersweet aspect to it just like any time you reach the completion of something that has dominated one's life for several years."

Various crew members left behind their children or long-term partner for this once-in-a-lifetime experience, according to an earlier article, which also notes that NASA is paying the participants $10 per hour "for all waking hours, up to 16 hours per day. That's as much as $60,480 for the 378-day mission."

Engadget points out there are already plans for two more one-year "missions" — with the second one expected to begin next spring...

I'm curious. Would any Slashdot readers be willing to spend a year in a mock Mars habitat?

New York City announced a "major citywide initiative" to increase "math achievement" among students, according to the mayor's office.

93 middle schools and 420 high schools will implement an "Illustrative Math" curriculum (from an education nonprofit founded in 2011) combined with intensive teacher coaching, starting this fall. "The goal is to ensure that all New York City students develop math skills," according to the NYC Solves web site (with the mayor's office noting "years of stagnant math scores.") Long-time Slashdot reader theodp writes: The NYC Public Schools further explained, "As part of the NYC Solves initiative, all high schools will use Illustrative Mathematics and districts will choose a comprehensive, evidence-based curricula for middle school math instruction from an approved list. Each curriculum has been reviewed and recommended by EdReports, a nationally recognized nonprofit organization."

The About page for Illustrative Mathematics (IM) lists The Bill & Melinda Gates Foundation as a Philanthropic Supporter [as well as the Chan Zuckerberg Initiative and The William and Flora Hewlett Foundation], and lists two Gates Foundation Directors as Board members... A search of Gates Foundation records for "Illustrative Mathematics" turns up $25 million in committed grants since 2012, including a $13.9 million grant to Illustrated Mathematics in Nov. 2022 ("To support the implementation of high-quality instructional materials and practices for improving students' math experience and outcomes") and a $425,000 grant just last month to Educators for Excellence ("To engage teacher feedback on the implementation of Illustrative Mathematics curriculum and help middle school teachers learn about the potential for math high-quality instructional materials and professional learning in New York City").

EdReports, which vouched for the Illustrative Mathematics curriculum (according to New York's Education Department), has received $10+ million in committed Gates Foundation grants. The Gates Foundation is also a very generous backer of NYC's Fund for Public Schools, with grants that included $4,276,973 in October 2023 "to support the implementation of high-quality instructional materials and practices for improving students' math experience and outcomes."

Chalkbeat reported in 2018 on a new focus on high school curriculum by the Gates Foundation ("an area where we feel like we've underinvested," said Bill Gates). The Foundation made math education its top K-12 priority in Oct. 2022 with a $1.1 billion investment. Also note this May 2023 blog post from $14+ million Gates Foundation grantee Educators for Excellence, a New York City nonprofit. The blog post touts the key role the nonprofit had played in a year-long advocacy effort that ultimately "secured a major win" ending the city's curricula "free-for-all" and announced "a standardized algebra curriculum from Illustrative Mathematics will also be piloted at 150 high schools."

As the NY Times reported back in 2011, behind "grass-roots" school advocacy, there's Bill Gates!

Longtime Slashdot reader Baron_Yam shares a report from Phys.Org, with the caption: "It's not sequestration, but it is a closed carbon loop and can store energy from renewable sources to be released when they are not collecting energy." From the report: Carbon in the atmosphere is a major driver of climate change. Now researchers from McGill University have designed a new catalyst for converting carbon dioxide (CO2) into methane -- a cleaner source of energy -- using tiny bits of copper called nanoclusters. While the traditional method of producing methane from fossil fuels introduces more CO2 into the atmosphere, the new process, electrocatalysis, does not. "On sunny days you can use solar power, or when it's a windy day you can use that wind to produce renewable electricity, but as soon as you produce that electricity you need to use it," says Mahdi Salehi, Ph.D. candidate at the Electrocatalysis Lab at McGill University. "But in our case, we can use that renewable but intermittent electricity to store the energy in chemicals like methane."

By using copper nanoclusters, says Salehi, carbon dioxide from the atmosphere can be transformed into methane and once the methane is used, any carbon dioxide released can be captured and "recycled" back into methane. This would create a closed "carbon loop" that does not emit new carbon dioxide into the atmosphere. The research, published recently in the journal Applied Catalysis B: Environment and Energy, was enabled by the Canadian Light Source (CLS) at the University of Saskatchewan (USask). The team plans to continue refining their catalyst to make it more efficient and investigate its large-scale, industrial applications. Their hope is that their findings will open new avenues for producing clean, sustainable energy.

An anonymous reader quotes a report from CNN: Deep inside Earth is a solid metal ball that rotates independently of our spinning planet, like a top whirling around inside a bigger top, shrouded in mystery. This inner core has intrigued researchers since its discovery by Danish seismologist Inge Lehmann in 1936, and how it moves -- its rotation speed and direction -- has been at the center of a decades-long debate. A growing body of evidence suggests the core's spin has changed dramatically in recent years, but scientists have remained divided over what exactly is happening -- and what it means. Part of the trouble is that Earth's deep interior is impossible to observe or sample directly. Seismologists have gleaned information about the inner core's motion by examining how waves from large earthquakes that ping this area behave. Variations between waves of similar strengths that passed through the core at different times enabled scientists to measure changes in the inner core's position and calculate its spin.

"Differential rotation of the inner core was proposed as a phenomenon in the 1970s and '80s, but it wasn't until the '90s that seismological evidence was published," said Dr. Lauren Waszek, a senior lecturer of physical sciences at James Cook University in Australia. But researchers argued over how to interpret these findings, "primarily due to the challenge of making detailed observations of the inner core, due to its remoteness and limited available data," Waszek said. As a result, "studies which followed over the next years and decades disagree on the rate of rotation, and also its direction with respect to the mantle," she added. Some analyses even proposed that the core didn't rotate at all.

One promising model proposed in 2023 described an inner core that in the past had spun faster than Earth itself, but was now spinning slower. For a while, the scientists reported, the core's rotation matched Earth's spin. Then it slowed even more, until the core was moving backward relative to the fluid layers around it. At the time, some experts cautioned that more data was needed to bolster this conclusion, and now another team of scientists has delivered compelling new evidence for this hypothesis about the inner core's rotation rate. Research published June 12 in the journal Nature not only confirms the core slowdown, it supports the 2023 proposal that this core deceleration is part of a decades-long pattern of slowing down and speeding up. The new findings also confirm that the changes in rotational speed follow a 70-year cycle, said study coauthor Dr. John Vidale, Dean's Professor of Earth Sciences at the University of Southern California's Dornsife College of Letters, Arts and Sciences.

No leap second will be added to universal time in 2024, the International Earth Rotation and Reference Systems Service (IERS) has announced. From a report: An additional second has previously been added to the universal time as displayed by atomic clocks (UTC) when this measurement has become out of sync with the rotation of the Earth (UT1).

But in a statement released on Thursday, the IERS, which enacts changes to UTC on behalf of the International Telecommunications Union (ITU), said the difference between UTC and UT1 is not great enough to warrant a change. Changes in the relationship between UTC and UT1 sometimes occur because the Earth does not always spin at the same speed, with natural events such as earthquakes often causing small changes.

New research aimed at identifying foods that contain higher levels of PFAS found people who eat more white rice, coffee, eggs and seafood typically showed more of the toxic chemicals in their plasma and breast milk. The Guardian adds: The study checked samples from 3,000 pregnant mothers, and is among the first research to suggest coffee and white rice may be contaminated at higher rates than other foods. It also identified an association between red meat consumption and levels of PFOS, one of the most common and dangerous PFAS compounds. The authors said the findings highlight the chemicals' ubiquity and the many ways they can end up in the food supply.

An anonymous reader quotes a report from Axios: The Food and Drug Administration will no longer allow the use of brominated vegetable oil (BVO) in food products and sodas due to concerns it poses a threat to people's health, the FDA announced Tuesday. The ban follows similar action in California against the food additive that's modified with bromine, which has been used in small quantities as a stabilizer in some citrus-flavored drinks and which is also found in fire retardants.

Jim Jones, the deputy commissioner for the FDA's Human Foods Program, said in a statement that "removal of the only authorized use of BVO from the food supply was based on a thorough review of current science and research findings that raised safety concerns." The FDA "concluded that the intended use of BVO in food is no longer considered safe after the results of studies conducted in collaboration with the National Institutes of Health (NIH) found the potential for adverse health effects in humans," per an agency statement. A 2022 FDA study found that oral exposure to the additive "is associated with increased tissue levels of bromine and that at high levels of exposure the thyroid is a target organ of potential negative health effects in rodents." The ban takes effect on August 2. Companies will have one year from then to "reformulate, relabel, and deplete the inventory of BVO-containing products before the FDA begins enforcing the final rule," according to the agency.

Ars Technica's Eric Berger writes: On the day before Christmas last year, a Falcon 9 rocket launched from California and put two spy satellites into low-Earth orbit for the armed forces of Germany, which are collectively called the Bundeswehr. Initially, the mission appeared successful. The German satellite manufacturer, OHB, declared that the two satellites were "safely in orbit." The addition of the two SARah satellites completed a next-generation constellation of three reconnaissance satellites, the company said. However, six months later, the two satellites have yet to become operational. According to the German publication Der Spiegel, the antennas on the satellites cannot be unfolded. Engineers with OHB have tried to resolve the issue by resetting the flight software, performing maneuvers to vibrate or shake the antennas loose, and more to no avail. As a result, last week, German lawmakers were informed that the two new satellites will probably not go into operation as planned.

The three-satellite constellation known as SARah -- the SAR is a reference to the synthetic aperture radar capability of the satellites -- was ordered in 2013 at a cost of $800 million. The first of the three satellites, SARah 1, launched in June 2022 on a Falcon 9 rocket. This satellite was built by Airbus in southern Germany, and it has since gone into operation without any problems. The two smaller satellites built by OHB, flying with passive synthetic aperture radar reflectors, were intended to complement the SARah 1 satellite, which carries an active phased-array radar antenna. [...] According to the Der Spiegel report, the Bundeswehr says the two SARah satellites built by OHB remain the property of the German company and would only be turned over to the military once they were operational. As a result, the military says OHB will be responsible for building two replacement satellites. Shockingly, the German publication says that its sources indicated OBH did not fully test the functionality and deployment of the satellite antennas on the ground. This could not be confirmed.

Scientists in China have found a species of moss that is able to withstand Mars-like conditions. The species is called Syntrichia caninervis and it's found in regions including Antarctica and the Mojave desert. The Guardian reports: "The unique insights obtained in our study lay the foundation for outer space colonization using naturally selected plants adapted to extreme stress conditions," the team write. [...] Writing in the journal The Innovation, researchers in China describe how the desert moss not only survived but rapidly recovered from almost complete dehydration. It was also able to regenerate under normal growth conditions after spending up to five years at -80C and up to 30 days at -196C, and after exposure to gamma rays, with doses of around 500Gy even promoting new growth.

The team then created a set-up that had similar pressures, temperatures, gases and UV radiation to Mars. It found the moss survived in this Mars-like environment, and was able to regenerate under normal growth conditions, even after seven days of exposure. The team also noted plants that were dried before such exposure faired better. "Looking to the future, we expect that this promising moss could be brought to Mars or the moon to further test the possibility of plant colonization and growth in outer space," the researchers write.

The Rubik's Cube turns 50 this year, but it's far from retiring. At a recent San Francisco conference, math buffs and puzzle fans celebrated the enduring appeal of Erno Rubik's invention, reports The New York Times. With a mind-boggling 43 quintillion possible configurations, the Cube has inspired countless variants and found uses in education and art.

China's Ministry of Industry and Information Technology has announced plans to develop standards for brain-computer interface technology, signaling the country's intent to advance in this emerging field. The ministry said it would assemble a committee of experts from various sectors to draft guidelines for brain information encoding and decoding, data communication, and visualization.

Brain-computer interface technology, which enables direct communication between the brain and external devices, has gained prominence with ventures like Elon Musk's Neuralink in the United States. China's move suggests a shift from primarily academic research to more focused development, potentially rivaling Western competitors. Previous Chinese brain-computer interface efforts have been largely confined to university research. In March, state media reported a paralyzed patient regaining some mobility after receiving a brain implant developed by Tsinghua University.

An anonymous reader quotes a report from Phys.Org: New analyses from the Annenberg Public Policy Center find that public perceptions of scientists' credibility -- measured as their competence, trustworthiness, and the extent to which they are perceived to share an individual's values -- remain high, but their perceived competence and trustworthiness eroded somewhat between 2023 and 2024. The research also found that public perceptions of scientists working in artificial intelligence (AI) differ from those of scientists as a whole. [...] The five factors in Factors Assessing Science's Self-Presentation (FASS) are whether science and scientists are perceived to be credible and prudent, and whether they are perceived to overcome bias, correct error (self-correcting), and whether their work benefits people like the respondent and the country as a whole (beneficial). [...] In the FASS model, perceptions of scientists' credibility are assessed through perceptions of whether scientists are competent, trustworthy, and "share my values." The first two of those values slipped in the most recent survey. In 2024, 70% of those surveyed strongly or somewhat agree that scientists are competent (down from 77% in 2023) and 59% strongly or somewhat agree that scientists are trustworthy (down from 67% in 2023). The survey also found that in 2024, fewer people felt that scientists' findings benefit "the country as a whole" and "benefit people like me." In 2024, 66% strongly or somewhat agreed that findings benefit the country as a whole (down from 75% in 2023). Belief that scientists' findings "benefit people like me," also declined, to 60% from 68%. Taken together, those two questions make up the beneficial factor of FASS. The findings follow sustained attacks on climate and COVID-19-related science, and more recently, public concerns about the rapid development and deployment of artificial intelligence. Here's what the study found when comparing perceptions of scientists in general with climate and AI scientists: - Credibility: When asked about three factors underlying scientists' credibility, AI scientists have lower credibility in all three values.
- Competent: 0% strongly/somewhat agree that scientists are competent, but only 62% for climate scientists and 49% for AI scientists.
- Trustworthy: 59% agree scientists are trustworthy, 54% agree for climate scientists, 28% for AI scientists.
- Share my values: A higher number (38%) agree that climate scientists share my values than for scientists in general (36%) and AI scientists (15%). More people disagree with this for AI scientists (35%) than for the others.
- Prudence: Asked whether they agree or disagree that science by various groups of scientists "creates unintended consequences and replaces older problems with new ones," over half of those surveyed (59%) agree that AI scientists create unintended consequences and just 9% disagree.
- Overcoming bias: Just 42% of those surveyed agree that scientists "are able to overcome human and political biases," but only 21% feel that way about AI scientists. In fact, 41% disagree that AI scientists are able to overcome human political biases. In another area, just 23% agree that AI scientists provide unbiased conclusions in their area of inquiry and 38% disagree.
- Self-correction: Self-correction, or "organized skepticism expressed in expectations sustaining a culture of critique," as the FASS paper puts it, is considered by some as a "hallmark of science." AI scientists are seen as less likely than scientists or climate scientists to take action to prevent fraud; take responsibility for mistakes; or to have mistakes that are caught by peer review.
- Benefits: Asked about the benefits from scientists' findings, 60% agree that scientists' "findings benefit people like me," though just 44% agree for climate scientists and 35% for AI scientists. Asked about whether findings benefit the country as a whole, 66% agree for scientists, 50% for climate scientists and 41% for AI scientists.
- Your best interest: The survey also asked respondents how much trust they have in scientists to act in the best interest of people like you. (This specific trust measure is not a part of the FASS battery.) Respondents have less trust in AI scientists than in others: 41% have a great deal/a lot of trust in medical scientists; 39% in climate scientists; 36% in scientists; and 12% in AI scientists.

"A federal grand jury has indicted an embattled Alzheimer's researcher for allegedly falsifying data to fraudulently obtain $16 million in federal research funding from the National Institutes of Health for the development of a controversial Alzheimer's drug and diagnostic test," writes Beth Mole via Ars Technica. "Wang is charged with one count of major fraud against the United States, two counts of wire fraud, and one count of false statements. If convicted, he faces a maximum penalty of 10 years in prison for the major fraud charge, 20 years in prison for each count of wire fraud, and five years in prison for the count of false statements [...]." From the report: Hoau-Yan Wang, 67, a medical professor at the City University of New York, was a paid collaborator with the Austin, Texas-based pharmaceutical company Cassava Sciences. Wang's research and publications provided scientific underpinnings for Cassava's Alzheimer's treatment, Simufilam, which is now in Phase III trials. Simufilam is a small-molecule drug that Cassava claims can restore the structure and function of a scaffolding protein in the brain of people with Alzheimer's, leading to slowed cognitive decline. But outside researchers have long expressed doubts and concerns about the research.

In 2023, Science magazine obtained a 50-page report from an internal investigation at CUNY that looked into 31 misconduct allegations made against Wang in 2021. According to the report, the investigating committee "found evidence highly suggestive of deliberate scientific misconduct by Wang for 14 of the 31 allegations," the report states. The allegations largely centered around doctored and fabricated images from Western blotting, an analytical technique used to separate and detect proteins. However, the committee couldn't conclusively prove the images were falsified "due to the failure of Dr. Wang to provide underlying, original data or research records and the low quality of the published images that had to be examined in their place." In all, the investigation "revealed long-standing and egregious misconduct in data management and record keeping by Dr. Wang," and concluded that "the integrity of Dr. Wang's work remains highly questionable." The committee also concluded that Cassava's lead scientist on its Alzheimer's disease program, Lindsay Burns, who was a frequent co-author with Wang, also likely bears some responsibility for the misconduct.

In March 2022, five of Wang's articles published in the journal PLOS One were retracted over integrity concerns with images in the papers. Other papers by Wang have also been retracted or had statements of concern attached to them. Further, in September 2022, the Food and Drug Administration conducted an inspection of the analytical work and techniques used by Wang to analyze blood and cerebrospinal fluid from patients in a simufilam trial. The investigation found a slew of egregious problems, which were laid out in a "damning" report (PDF) obtained by Science. In the indictment last week (PDF), federal authorities were explicit about the allegations, claiming that Wang falsified the results of his scientific research to NIH "by, among other things, manipulating data and images of Western blots to artificially add bands [which represent proteins], subtract bands, and change their relative thickness and/or darkness, and then drawing conclusions" based on those false results.

An anonymous reader shares a report: When someone loses part of a leg, a prosthetic can make it easier to get around. But most prosthetics are static, cumbersome, and hard to move. A new neural interface connects a bionic limb to nerve endings in the thigh, allowing the limb to be controlled by the brain. The new device, which is described today in Nature Medicine, could help people with lower-leg amputations feel as if their prosthesis is part of them. "When you ask a patient 'What is your body?' They don't include the prosthesis," says MIT biophysicist Hugh Herr, one of the lead authors on the study. The work is personal for him: he lost both his lower legs in a climbing accident when he was 17. He says linking the brain to the prosthesis can make it feel more like part of someone's anatomy, which can have a positive emotional impact.

Getting the neural interface hooked up to a prosthetic takes two steps. First, patients undergo surgery. Following a lower leg amputation, portions of shin and calf muscle still remain. The operation connects shin muscle, which contracts to make the ankle flex upward, to calf muscle, which counteracts this movement. The prosthetic can also be fitted at this point. Reattaching the remnants of these muscles can enable the prosthetic to move more dynamically. It can also reduce phantom limb pain, and patients are less likely to trip and fall. "The surgery stands on its own," says Amy Pietrafitta, a para-athlete who received it in 2018. "I feel like I have my leg back." But natural movements are still limited when the prosthetic isn't connected to the nervous system.

In step two, surface electrodes measure nerve activity from the brain to the calf and shin muscles, indicating an intention to move the lower leg. A small computer in the bionic leg decodes those nerve signals and moves the leg accordingly, allowing the patient to move the limb more naturally. "If you have intact biological limbs, you can walk up and down steps, for example, and not even think about it. It's involuntary," says Herr. "That's the case with our patients, but their limb is made of titanium and silicone." The authors compared the mobility of seven patients using a neural interface with that of patients who had not received the surgery. Patients using the neural interface could walk 41% faster and climb sloped surfaces and steps. They could also dodge obstacles more nimbly and had better balance. And they described feeling that the prosthetic was truly a part of their body rather than just a tool that they used to get around.