It’s possible that I shall make an ass of myself. But in that case one can always get out of it with a little dialectic. I have, of course, so worded my proposition as to be right either way (K.Marx, Letter to F.Engels on the Indian Mutiny)
Thursday, January 04, 2024
Researchers identify path to prevent cognitive decline after radiation
Researchers at the Del Monte Institute for Neuroscience at the University of Rochester find that microglia—the brain’s immune cells—can trigger cognitive deficits after radiation exposure and may be a key target for preventing these symptoms. These findings, out today in the International Journal of Radiation Oncology Biology Biophysics, build on previous research showing that after radiation exposure microglia damage synapses, the connections between neurons that are important for cognitive behavior and memory.
“Cognitive deficits after radiation treatment are a major problem for cancer survivors,” M. Kerry O’Banion, MD, PhD, professor of Neuroscience, member of the Wilmot Cancer Institute, and senior author of the study said. “This research gives us a possible target to develop therapies to prevent or mitigate against such deficits in people who need brain radiotherapy.”
Using several behavioral tests, researchers investigated the cognitive function of mice before and after radiation exposure. Female mice performed the same throughout, indicating a resistance to radiation injury. However, researchers found male mice could not remember or perform certain tasks after radiation exposure. This cognitive decline correlates with the loss of synapses and evidence of potentially damaging microglial over-reactivity following the treatment.
Researchers then targeted the pathway in microglia important to synapse removal. Mice with these mutant microglia had no cognitive decline following radiation. And others that were given the drug, Leukadherin-1, which is known to block this same pathway, during radiation treatment, also had no cognitive decline.
"This could be the first step in substantially improving a patient's quality of life and need for greater care,” said O’Banion. “Moving forward, we are particularly interested in understanding the signals that target synapses for removal and the fundamental signaling mechanisms that drive microglia to remove these synapses. We believe that both avenues of research offer additional targets for developing therapies to help individuals receiving brain radiotherapy.”
O’Banion also believes this work may have broader implications because some of these mechanisms are connected to Alzheimer's and other neurodegenerative diseases.
Additional authors include first author Joshua Hinkle, PhD, postdoctoral fellow at the National Institute on Drug Abuse and former graduate student in the O’Banion-Olschowka Labs, John Olschowka, PhD, and Jacqueline Williams, PhD, of the University of Rochester Medical Center. This research was supported by the National Institutes of Health, and NASA.
JOURNAL
International Journal of Radiation Oncology*Biology*Physics
CREDIT: LILY ARMSTRONG-DAVIES, MEDICAL ILLUSTRATOR
Mount Sinai researchers have shown for the first time that a person’s beliefs related to drugs can influence their own brain activity and behavioral responses in a way comparable to the dose-dependent effects of pharmacology.
The implications of the study, which directly focused on beliefs about nicotine, are profound. They range from elucidating how the neural mechanisms underlying beliefs may play a key role in addiction, to optimizing pharmacological and nonpharmacological treatments by leveraging the power of human beliefs. The study was published in the journal Nature Mental Health.
“Beliefs can have a powerful influence on our behavior, yet their effects are considered imprecise and rarely examined by quantitative neuroscience methods,” says Xiaosi Gu, PhD, Associate Professor of Psychiatry, and Neuroscience, at the Icahn School of Medicine at Mount Sinai, and senior author of the study. “We set out to investigate if human beliefs can modulate brain activities in a dose-dependent manner similar to what drugs do, and found a high level of precision in how beliefs can influence the human brain. This finding could be crucial for advancing our knowledge about the role of beliefs in addiction as well as a broad range of disorders and their treatments.”
To explore this dynamic, the Mount Sinai team, led by Ofer Perl, PhD, a postdoctoral fellow in Dr. Gu’s lab when the study was conducted, instructed nicotine-dependent study participants to believe that an electronic cigarette they were about to vape contained either low, medium, or high strengths of nicotine, when in fact the level remained constant. Participants then underwent functional neuroimaging (fMRI) while performing a decision-making task known to engage neural circuits activated by nicotine.
The scientists found that the thalamus, an important binding site for nicotine in the brain, showed a dose-dependent response to the subject’s beliefs about nicotine strength, providing compelling evidence to support the relationship between subjective beliefs and biological substrates in the human brain. This effect was previously thought to apply only to pharmacologic agents. A similar dose-dependent effect of beliefs was also found in the functional connectivity between the thalamus and the ventromedial prefrontal cortex, a brain region that is considered important for decision-making and belief states.
“Our findings provide a mechanistic explanation for the well-known variations in individual responses to drugs,” notes Dr. Gu, “and suggest that subjective beliefs could be a direct target for the treatment of substance use disorders. They could also advance our understanding of how cognitive interventions, such as psychotherapy, work at the neurobiological level in general for a wide range of psychiatric conditions beyond addiction.”
Dr. Gu, who is one of the world’s foremost researchers in the emerging field of computational psychiatry, cites another way in which her team’s research could inform clinical care. “The finding that human beliefs about drugs play such a pivotal role suggests that we could potentially enhance patients’ responses to pharmacological treatments by leveraging these beliefs,” she explains.
Significantly, the work of the Mount Sinai team can also be viewed in a much broader context: harnessing beliefs in a systematic manner to better serve mental health treatment and research in general.
“We’re interested in testing the effects of beliefs on drugs beyond nicotine to include addictive substances like cannabis and alcohol, and therapeutic agents like antidepressants and psychedelics,” says Dr. Gu. “It would be fascinating to examine, for example, how the potency of a drug might impact the effect of drug-related beliefs on the brain and behavior, and how long-lasting the impact of those beliefs might be. Our findings could potentially revolutionize how we view drugs and therapy in a much broader context of health.”
About the Mount Sinai Health System Mount Sinai Health System is one of the largest academic medical systems in the New York metro area, with more than 43,000 employees working across eight hospitals, more than 400 outpatient practices, more than 300 labs, a school of nursing, and a leading school of medicine and graduate education. Mount Sinai advances health for all people, everywhere, by taking on the most complex health care challenges of our time—discovering and applying new scientific learning and knowledge; developing safer, more effective treatments; educating the next generation of medical leaders and innovators; and supporting local communities by delivering high-quality care to all who need it. Through the integration of its hospitals, labs, and schools, Mount Sinai offers comprehensive health care solutions from birth through geriatrics, leveraging innovative approaches such as artificial intelligence and informatics while keeping patients’ medical and emotional needs at the center of all treatment. The Health System includes approximately 7,400 primary and specialty care physicians; 13 joint-venture outpatient surgery centers throughout the five boroughs of New York City, Westchester, Long Island, and Florida; and more than 30 affiliated community health centers. Hospitals within the System are consistently ranked by Newsweek’s® “The World’s Best Smart Hospitals, Best in State Hospitals, World Best Hospitals and Best Specialty Hospitals” and by U.S. News & World Report's® “Best Hospitals” and “Best Children’s Hospitals.” The Mount Sinai Hospital is on the U.S. News & World Report® “Best Hospitals” Honor Roll for 2023-2024.
UNIVERSITY OF ILLINOIS GRAINGER COLLEGE OF ENGINEERING
IMAGE:
A WAFER CONTAINING MEMRISTORS FABRICATED WITH HIGH-QUALITY TWO-DIMENSIONAL CARBON PROCESSED FROM BITUMINOUS BLUE GEM COAL MINED IN SOUTHEASTERN KENTUCKY, TWO SAMPLES OF WHICH ARE SHOWN HERE.
CREDIT: THE GRAINGER COLLEGE OF ENGINEERING AT UNIVERSITY OF ILLINOIS URBANA-CHAMPAIGN
Coal is an abundant resource in the United States that has, unfortunately, contributed to climate change through its use as a fossil fuel. As the country transitions to other means of energy production, it will be important to consider and reevaluate coal’s economic role. A joint research effort from the University of Illinois Urbana-Champaign, the National Energy Technology Laboratory, Oak Ridge National Laboratory and the Taiwan Semiconductor Manufacturing Company has shown how coal can play a vital role in next-generation electronic devices.
“Coal is usually thought of as something bulky and dirty, but the processing techniques we’ve developed can transform it into high-purity materials just a couple of atoms thick,” said Qing Cao, a U. of I. materials science & engineering professor and a co-lead of the collaboration. “Their unique atomic structures and properties are ideal for making some of the smallest possible electronics with performance superior to state-of-the art.”
A process developed by the NETL first converts coal char into nanoscale carbon disks called “carbon dots” that the U. of I. research group demonstrated can be connected to form atomically thin membranes for applications in both two-dimensional transistors and memristors, technologies that will be critical to constructing more advanced electronics. These results are reported in the journal Communications Engineering.
Perfect for 2D electronics
In the ongoing search for smaller, faster and more efficient electronics, the final step will be devices made with materials just one or two atoms thick. It is impossible for devices to be smaller than this limit, and their small scale often makes them operate much quicker and consume far less energy. While ultrathin semiconductors have been extensively studied, it is also necessary to have atomically thin insulators – materials that block electric currents – to construct working electronic devices like transistors and memristors.
Atomically thin layers of carbon with disordered atomic structures can function as an excellent insulator for constructing two-dimensional devices. The researchers in the collaboration have shown that such carbon layers can be formed from carbon dots derived from coal char. To demonstrate their capabilities, the U. of I. group led by Cao developed two examples of two-dimensional devices.
“It’s really quite exciting, because this is the first time that coal, something we normally see as low-tech, has been directly linked to the cutting edge of microelectronics,” Cao said.
Transistor dielectric
Cao’s group used coal-derived carbon layers as the gate dielectric in two-dimensional transistors built on the semimetal graphene or semiconductor molybdenum disulfide to enable more than two times faster device operating speed with lower energy consumption. Like other atomically thin materials, the coal-derived carbon layers do not possess “dangling bonds,” or electrons that are not associated with a chemical bond. These sites, which are abundant on the surface of conventional three-dimensional insulators, alter their electrical properties by effectively functioning as “traps,” slowing down the transport of mobile charges and thus the transistor switching speed.
However, unlike other atomically thin materials, the new coal-derived carbon layers are amorphous, meaning that they do not possess a regular, crystalline structure. They therefore do not have boundaries between different crystalline regions that serve as conduction pathways leading to “leakage,” where undesired electrical currents flow through the insulator and cause substantial additional power consumption during device operations.
Memristor filament
Another application Cao’s group considered is memristors – electronic components capable of both storing and operating on data to greatly enhance the implementation of AI technology. These devices store and represent data by modulating a conductive filament formed by electrochemical reactions between a pair of electrodes with the insulator sandwiched in between.
The researchers found that the adoption of ultrathin coal-derived carbon layers as the insulator allows the fast formation of such filament with low energy consumption to enable high device operating speed with low power. Moreover, atomic size rings in these coal-derived carbon layers confine the filament to enhance the reproducible device operations for enhanced data storage fidelity and reliability.
From research to production
The new devices developed by the Cao group provide proof-of-principle for the use of coal-derived carbon layers in two-dimensional devices. What remains is to show that such devices can be manufactured on large scales.
“The semiconductor industry, including our collaborators at Taiwan Semiconductor, is very interested in the capabilities of two-dimensional devices, and we’re trying to fulfill that promise,” Cao said. “Over the next few years, the U. of I. will continue to collaborate with NETL to develop a fabrication process for coal-based carbon insulators that can be implemented in industrial settings.”
TWO MILLION GIGABYTES OF SATELLITE IMAGERY WERE ANALYZED TO DETECT OFFSHORE INFRASTRUCTURE IN COASTAL WATERS ACROSS SIX CONTINENTS WHERE MORE THAN THREE-QUARTERS OF INDUSTRIAL ACTIVITY IS CONCENTRATED.
WASHINGTON, D.C. - A new study published today in the journal Nature offers an unprecedented view of previously unmapped industrial use of the ocean and how it is changing.
The groundbreaking study, led by Global Fishing Watch, uses machine learning and satellite imagery to create the first global map of large vessel traffic and offshore infrastructure, finding a remarkable amount of activity that was previously “dark” to public monitoring systems.
The analysis reveals that about 75 percent of the world’s industrial fishing vessels are not publicly tracked, with much of that fishing taking place around Africa and south Asia. More than 25 percent of transport and energy vessel activity are also missing from public tracking systems.
“A new industrial revolution has been emerging in our seas undetected—until now,” said David Kroodsma, director of research and innovation at Global Fishing Watch and co-lead author of the study. “On land, we have detailed maps of almost every road and building on the planet. In contrast, growth in our ocean has been largely hidden from public view. This study helps eliminate the blind spots and shed light on the breadth and intensity of human activity at sea.”
Researchers from Global Fishing Watch, the University of Wisconsin-Madison, Duke University, UC Santa Barbara and SkyTruth analyzed 2 million gigabytes of satellite imagery spanning 2017-2021 to detect vessels and offshore infrastructure in coastal waters across six continents where more than three-quarters of industrial activity is concentrated.
By synthesizing GPS data with five years of radar and optical imagery, the researchers were able to identify vessels that failed to broadcast their positions. Using machine learning, they then concluded which of those vessels were likely engaged in fishing activity.
“Historically, vessel activity has been poorly documented, limiting our understanding of how the world’s largest public resource—the ocean—is being used,” said co-lead author Fernando Paolo, senior machine learning engineer at Global Fishing Watch. “By combining space technology with state-of-the-art machine learning, we mapped undisclosed industrial activity at sea on a scale never done before.”
While not all boats are legally required to broadcast their position, vessels absent from public monitoring systems, often termed “dark fleets,” pose major challenges for protecting and managing natural resources. Researchers found numerous dark fishing vessels inside many marine protected areas, and a high concentration of vessels in many countries’ waters that previously showed little-to-no vessel activity by public monitoring systems.
“Publicly available data wrongly suggests that Asia and Europe have similar amounts of fishing within their borders, but our mapping reveals that Asia dominates—for every 10 fishing vessels we found on the water, seven were in Asia while only one was in Europe," said co-author Jennifer Raynor, assistant professor of natural resource economics at the University of Wisconsin-Madison. “By revealing dark vessels, we have created the most comprehensive public picture of global industrial fishing available.”
The study also shows how human activity in the ocean is changing. Coinciding with the COVID-19 pandemic, fishing activity dropped globally by about 12 percent, with an 8 percent decline in China and a 14 percent drop elsewhere. In contrast, transport and energy vessel activity remained stable.
Offshore energy development surged during the study period. Oil structures increased by 16 percent, while wind turbines more than doubled. By 2021, turbines outnumbered oil platforms. China’s offshore wind energy had the most striking growth, increasing ninefold from 2017 to 2021.
“The footprint of the Anthropocene is no longer limited to terra firma,” said co-author Patrick Halpin, professor of marine geospatial ecology at Duke University. “Having a more complete view of ocean industrialization allows us to see new growth in offshore wind, aquaculture and mining that is rapidly being added to established industrial fishing, shipping and oil and gas activities. Our work reveals that the global ocean is a busy, crowded and complex industrial workspace of the growing blue economy.”
The study highlights the potential of this new technology to tackle climate change. Mapping all vessel traffic will improve estimates of greenhouse gas emissions at sea, while maps of infrastructure can inform wind development or aid in tracking marine degradation caused by oil exploration.
“Identifying offshore infrastructure is critical for understanding offshore energy development impacts and trends, and is crucial data for our work to detect marine pollution events and hold responsible parties to account,” said co-author Christian Thomas, a geospatial engineer at SkyTruth.
The open data and technology used in the study can help governments, researchers and civil society to identify hotspots of potentially illegal activity, determine where industrial fishing vessels may be encroaching on artisanal fishing grounds, or simply better understand vessel traffic in their waters.
“Previously, this type of satellite monitoring was only available to those who could pay for it. Now it is freely available to all nations,” concluded Kroodsma. “This study marks the beginning of a new era in ocean management and transparency.”
The study was made possible thanks to the generous support of Bloomberg Philanthropies, National Geographic Pristine Seas and Oceankind, and our technology partner, Google. As an awardee of The Audacious Project, a collaborative funding initiative that is catalyzing social impact on a grand scale, Global Fishing Watch is able to further the application of this innovative work.
Global Map of Offshore Infrastructure, 2017-2021
Two million gigabytes of satellite imagery were analyzed to detect offshore infrastructure in coastal waters across six continents where more than three-quarters of industrial activity is concentrated.
Composite view of the North Sea showing all mapped industrial use in the region
The study used machine learning and satellite imagery to create the first global map of vessel traffic and offshore infrastructure, offering an unprecedented view of previously unmapped industrial use of the ocean.
About The Study: This study that included 525 Black adolescents found an association between individual online racial discrimination and posttraumatic stress disorder symptoms and between posttraumatic stress disorder symptoms and suicidal ideation. These risk factors are important to consider in continuing studies of the cause of suicidal ideation for Black adolescents in the U.S.
Authors: Brendesha M. Tynes, Ph.D., of the University of Southern California, Los Angeles, is the corresponding author.
Editor’s Note: Please see the article for additional information, including other authors, author contributions and affiliations, conflict of interest and financial disclosures, and funding and support.
RESEARCHERS AT THE GEORGIA INSTITUTE OF TECHNOLOGY HAVE CREATED THE WORLD’S FIRST FUNCTIONAL SEMICONDUCTOR MADE FROM GRAPHENE, A SINGLE SHEET OF CARBON ATOMS HELD TOGETHER BY THE STRONGEST BONDS KNOWN. THE BREAKTHROUGH THROWS OPEN THE DOOR TO A NEW WAY OF DOING ELECTRONICS.
Researchers at the Georgia Institute of Technology have created the world’s first functional semiconductor made from graphene, a single sheet of carbon atoms held together by the strongest bonds known. Semiconductors, which are materials that conduct electricity under specific conditions, are foundational components of electronic devices. The team’s breakthrough throws open the door to a new way of doing electronics.
Their discovery comes at a time when silicon, the material from which nearly all modern electronics are made, is reaching its limit in the face of increasingly faster computing and smaller electronic devices. Walter de Heer, Regents’ Professor of physics at Georgia Tech, led a team of researchers based in Atlanta, Georgia, and Tianjin, China, to produce a graphene semiconductor that is compatible with conventional microelectronics processing methods — a necessity for any viable alternative to silicon.
In this latest research, published in Nature, de Heer and his team overcame the paramount hurdle that has been plaguing graphene research for decades, and the reason why many thought graphene electronics would never work. Known as the “band gap,” it is a crucial electronic property that allows semiconductors to switch on and off. Graphene didn’t have a band gap — until now.
“We now have an extremely robust graphene semiconductor with 10 times the mobility of silicon, and which also has unique properties not available in silicon,” de Heer said. “But the story of our work for the past 10 years has been, ‘Can we get this material to be good enough to work?’”
A New Type of Semiconductor
De Heer started to explore carbon-based materials as potential semiconductors early in his career, and then made the switch to exploring two-dimensional graphene in 2001. He knew then that graphene had potential for electronics.
“We were motivated by the hope of introducing three special properties of graphene into electronics,” he said. “It’s an extremely robust material, one that can handle very large currents, and can do so without heating up and falling apart.”
De Heer achieved a breakthrough when he and his team figured out how to grow graphene on silicon carbide wafers using special furnaces. They produced epitaxial graphene, which is a single layer that grows on a crystal face of the silicon carbide. The team found that when it was made properly, the epitaxial graphene chemically bonded to the silicon carbide and started to show semiconducting properties.
Over the next decade, they persisted in perfecting the material at Georgia Tech and later in collaboration with colleagues at the Tianjin International Center for Nanoparticles and Nanosystems at Tianjin University in China. De Heer founded the center in 2014 with Lei Ma, the center’s director and a co-author of the paper.
How They Did It
In its natural form, graphene is neither a semiconductor nor a metal, but a semimetal. A band gap is a material that can be turned on and off when an electric field is applied to it, which is how all transistors and silicon electronics work. The major question in graphene electronics research was how to switch it on and off so it can work like silicon.
But to make a functional transistor, a semiconducting material must be greatly manipulated, which can damage its properties. To prove that their platform could function as a viable semiconductor, the team needed to measure its electronic properties without damaging it.
They put atoms on the graphene that “donate” electrons to the system — a technique called doping, used to see whether the material was a good conductor. It worked without damaging the material or its properties.
The team’s measurements showed that their graphene semiconductor has 10 times greater mobility than silicon. In other words, the electrons move with very low resistance, which, in electronics, translates to faster computing. “It’s like driving on a gravel road versus driving on a freeway,” de Heer said. “It’s more efficient, it doesn’t heat up as much, and it allows for higher speeds so that the electrons can move faster.”
The team’s product is currently the only two-dimensional semiconductor that has all the necessary properties to be used in nanoelectronics, and its electrical properties are far superior to any other 2D semiconductors currently in development.
“A long-standing problem in graphene electronics is that graphene didn’t have the right band gap and couldn’t switch on and off at the correct ratio,” said Ma. “Over the years, many have tried to address this with a variety of methods. Our technology achieves the band gap, and is a crucial step in realizing graphene-based electronics.”
Moving Forward
Epitaxial graphene could cause a paradigm shift in the field of electronics and allow for completely new technologies that take advantage of its unique properties. The material allows the quantum mechanical wave properties of electrons to be utilized, which is a requirement for quantum computing.
“Our motivation for doing graphene electronics has been there for a long time, and the rest was just making it happen,” de Heer said. “We had to learn how to treat the material, how to make it better and better, and finally how to measure the properties. That took a very, very long time.”
According to de Heer, it is not unusual to see yet another generation of electronics on its way. Before silicon, there were vacuum tubes, and before that, there were wires and telegraphs. Silicon is one of many steps in the history of electronics, and the next step could be graphene.
“To me, this is like a Wright brothers moment,” de Heer said. “They built a plane that could fly 300 feet through the air. But the skeptics asked why the world would need flight when it already had fast trains and boats. But they persisted, and it was the beginning of a technology that can take people across oceans.”
Citation: Zhao, J. et al. Ultrahigh-mobility semiconducting epitaxial graphene on silicon carbide. Nature (2024).
The Georgia Institute of Technology, or Georgia Tech, is one of the top public research universities in the U.S., developing leaders who advance technology and improve the human condition. The Institute offers business, computing, design, engineering, liberal arts, and sciences degrees. Its more than 45,000 undergraduate and graduate students, representing 50 states and more than 148 countries, study at the main campus in Atlanta, at campuses in France and China, and through distance and online learning. As a leading technological university, Georgia Tech is an engine of economic development for Georgia, the Southeast, and the nation, conducting more than $1 billion in research annually for government, industry, and society.
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A single crystal silicon carbide wafer that has been cut into square chips.
The team's graphene device grown on a silicon carbide substrate chip.
De Heer's patented induction furnace used to produce graphene on silicon carbide.
Molecular models of graphene and silicon carbide.
A vial of graphene grown in a furnace at de Heer's lab at Georgia Tech.
Walter de Heer, professor of physics at the Georgia Institute of Technology, holds a silicon carbide wafer.
