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New computer simulations help scientists advance energy-efficient microelectronics

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New computer simulations help scientists advance energy-efficient microelectronics


New computer simulations help scientists advance energy-efficient microelectronics
a) Schematic structure of a field-effect transistor (FET) with ultra-thin HfO2/ZrO2-based ferroelectric gate oxide. The polycrystalline multi-phase and multi-domain ferroelectric film exhibits an effective negative capacitance (NC). b) Logarithm of the drain current as a function of the gate voltage Vg for a conventional FET and a negative capacitance FET (NCFET). For a matched Off-current Ioff the supply voltage can be reduced or the On-current Ion can be boosted at the same supply voltage. c) Simplified metal-ferroelectric-insulator-semiconductor-metal (MFISM) capacitor structure simulated in this study. d) Due to the NC effect, the MFISM capacitor shows an overall capacitance enhancement compared to an otherwise identical metal-insulator-semiconductor-metal (MISM) structure. Credit: Advanced Electronic Materials (2024). DOI: 10.1002/aelm.202400085

Thanks to advances in microchips, today’s smartphones are so powerful they would have been considered supercomputers in the early 1990s. But the rising ubiquity of artificial intelligence and the Internet of Things—the vast network of connected devices that have enabled everything from smart grids to smart homes—will require a new generation of microchips that not only outpace previous records of miniaturization and performance but are also more energy efficient than current technologies.

As part of this effort, Berkeley Lab scientists are working to revolutionize the transistor, one of the fundamental components in computer microchips, for superior performance and energy efficiency. Recent work has shown the promise of new transistor materials that use an unusual property called negative capacitance to enable more efficient memory and logic devices. When a material has negative capacitance, it can store a greater amount of electrical charge at lower voltages, which is the opposite of what happens in conventional capacitive materials.

Now, a multidisciplinary team of researchers have developed an atomistic understanding of the origins of negative capacitance, enabling them to enhance and customize this phenomenon for specific device applications. The advance was made possible by FerroX, an open-source, 3D simulation framework that the team custom-designed for the study of negative capacitance. Their work was reported in the journal Advanced Electronic Materials.

The work represents a significant milestone of a multiyear project, “Co-Design of Ultra-Low-Voltage Beyond CMOS Microelectronics,” which aims to design new microchips that could perform better and require less energy than conventional silicon chips.

While it’s not uncommon for materials development to be closely linked to applications, Berkeley Lab’s co-design approach to microelectronics research, where the atomistic understanding of material properties is driven and informed by specific device requirements, tightens the connection between research aims in all aspects of device development and relies on the interdisciplinary team science for which the lab is famous in the hope of accelerating the pathway from R&D to commercialization.

“There’s a lot of trial and error in the making of new materials. It’s like making a new recipe. Researchers typically have to work days and nights in the lab to change that recipe. But with our modeling tool, FerroX, you can use your own computer to target specific parameters that can affect the performance of the negative capacitance effect,” said Zhi (Jackie) Yao, a research scientist in Berkeley Lab’s Applied Mathematics & Computational Research Division and senior author on the study.

Yao and first author Prabhat Kumar, a postdoctoral scholar in the Applied Mathematics & Computational Research Division, co-led the development of FerroX for the microelectronics co-design project.

Uncovering the atomistic origins of negative capacitance

In 2008, co-author Sayeef Salahuddin, a professor of electrical engineering and computer sciences at UC Berkeley and senior faculty scientist in Berkeley Lab’s Materials Sciences Division, first proposed the concept of negative capacitance to demonstrate a new approach to designing energy-efficient computers.

Negative capacitance typically appears in materials with ferroelectric properties. Ferroelectric materials have promise as energy-efficient computer memories because their built-in electrical polarization can be used to store data, for example, that can be written and erased using a low-power electric field.

In the years following Salahuddin’s pioneering proposal, researchers have learned that the negative capacitance effect in thin films of ferroelectric hafnium oxide and zirconium oxide (HfO2-ZrO2) occurs when the films are composed of a mixture of phases.

That means that small regions or “grains” of the film have slightly different arrangements of atoms or “phases.” The size of these phase grains are tiny—just a few nanometers across—but the different phases have distinct electronic properties that can interact with each other and give rise to macroscopic phenomena such as negative capacitance.

The Salahuddin group has already made use of this phenomenon to produce record-breaking microcapacitors, but in order to unlock the full potential of negative capacitance, the researchers needed a deeper understanding of its atomistic origins.

To do this, a multidisciplinary team co-led by Yao and Kumar developed FerroX. The open-source framework allowed them to develop 3D phase-field simulations of a ferroelectric thin film, in which they could vary the phase composition at will and study the impacts on the film’s electronic properties.

“Our goal was to understand the origin of negative capacitance in these films, which is not well understood,” Kumar said. “Our simulations are the first to help researchers tailor a material’s properties for further improvements in negative capacitance observed in the lab.”

As a result, the Berkeley Lab researchers found that the negative capacitance effect can be enhanced by optimizing the domain structure—reducing the size of the ferroelectric grains and arranging them to have a particular direction of ferroelectric polarization.

“This approach to enhancing negative capacitance was unknown before our study because previous models lacked the scalability to easily explore the design space and lacked physics customization,” Yao said.

Yao attributes this new modeling capability to working firsthand with materials scientists like Salahuddin, who helped the FerroX development team understand how to shape their models around the physics of ferroelectrics, and to the unique multidisciplinary strengths of Berkeley Lab, where researchers across the scientific disciplines are in close proximity to the Perlmutter supercomputer at the Department of Energy’s National Energy Research Scientific Computing Center (NERSC).

Perlmutter supports complex simulation, data analytics, and artificial intelligence experiments requiring multiple graphics processing units (GPUs) at a time. Yao, Kumar, and team relied significantly on Perlmutter to develop FerroX, which is now available to other researchers as an open-source framework that is portable from laptops to supercomputers.

“It’s exciting that FerroX will be able to help such a vast community of researchers in academia, industry, and the national labs,” Yao said.

While FerroX models in the current study simulate the origin of negative capacitance as it evolves at the transistor gate, the Berkeley Lab team plans to use the open-source framework to simulate the entire transistor in future studies.

“Over the years, we have made significant progress in both the physics of negative capacitance and integrating that physics into real microelectronics devices,” said Salahuddin. “With FerroX, we can now model these devices starting from atoms, and that will allow us to design microelectronics devices with optimal negative capacitance performance. That would not have been possible without the strength of this co-design group of researchers spanning computing sciences and materials sciences.”

More information:
Prabhat Kumar et al, 3D Ferroelectric Phase Field Simulations of Polycrystalline Multi‐Phase Hafnia and Zirconia Based Ultra‐Thin Films, Advanced Electronic Materials (2024). DOI: 10.1002/aelm.202400085

Citation:
New computer simulations help scientists advance energy-efficient microelectronics (2024, September 12)
retrieved 12 September 2024
from https://techxplore.com/news/2024-09-simulations-scientists-advance-energy-efficient.html

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Managers can boost everyone’s productivity by praising successful workers in company-wide messaging

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Managers can boost everyone’s productivity by praising successful workers in company-wide messaging


work team
Credit: Pixabay/CC0 Public Domain

Workplace communications platforms such as Slack and Microsoft Teams are sometimes accused of reducing productivity by distracting workers with constant messages and the need to respond to them.

But new research by Wen Wen, associate professor of information, risk, and operations management (IROM) at Texas McCombs, shows that companies can use them to do the opposite: to motivate workers.

How? By praising successful employees in all-staff channels that everyone can see—especially when they can’t see one another face-to-face.

The paper is published in the journal MIS Quarterly.

“One important challenge faced by many companies is how to motivate remote workers and keep them productive,” says Wen. “Our research gives practical advice on how to construct the right messages regarding peers and how to share them on digital platforms in order to achieve a significant productivity gain.”

Power of praise

Wen—with fellow IROM professor Andrew Whinston of Texas McCombs, Stephen He of The University of Texas at San Antonio, and Haoyuan Liu of Nanyang Technological University—scrutinized data from a Chinese internet technology company with 340 sales employees spread across 28 branches.

Whenever a sales representative landed a deal, human resources representatives would alert all branch workers on a Slack-like app. The notes were lengthy, individualized, and garnished with emojis.

The researchers classified the messages into two types: ones that praised employees’ efforts and ones that praised employees’ abilities. How would those messages affect the performance of other employees, as measured by the number of phone calls they made to prospective subscribers?

The team found both kinds of messages boosted overall productivity.

  • For a 10 percentage-point increase in the intensity of messages praising efforts, other workers averaged 0.9 more calls a day.
  • The same amount of increase in messaging about abilities inspired other workers to make 1.2 more calls a day.

Distance Makes a difference

But the two kinds of messages had different effects, depending on whether other employees personally knew the ones being praised. Dividing relationships into “socially close” and “socially distant,” the study found:

  • Effort-focused notes boosted sales calls made by both close and distant colleagues, with no significant difference between them.
  • Ability-focused messages had strong motivating effects on close co-workers. For distant co-workers, however, call numbers were virtually unchanged.

The researchers got similar results from a second study, which surveyed 228 U.S. workers from a variety of companies.

Why did commending effort inspire more workers than commending ability? Wen points to prior psychological research.

People relate to another’s effort because they see it as controllable, actionable, and contributing to success, she says: “Individuals often exhibit heightened dedication when they perceive that the goals they pursue are more achievable.”

It’s a different story for ability-focused messages. People who are socially close see themselves as having similar abilities, and they work harder. But those who are distant are less likely to believe that they possess similar abilities or that they can acquire them anytime soon.

That’s a particularly important finding for companies with many remote workers, Wen notes. “They usually do not know each other due to the physical distance,” she says.

“For a distributed workforce, managers should probably consider crafting effort-focused messages when sharing peer successes, instead of ability-focused messages. People can be influenced by effort-focused messages about peers whom they don’t even know.”

More information:
Haoyuan Liu et al, Peer Influence in the Workplace: Evidence from an Enterprise Digital Platform, MIS Quarterly (2024). DOI: 10.25300/MISQ/2024/16308

Citation:
Study: Managers can boost everyone’s productivity by praising successful workers in company-wide messaging (2024, September 12)
retrieved 12 September 2024
from https://phys.org/news/2024-09-boost-productivity-successful-workers-company.html

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Experimental data help unravel the mystery surrounding the creation of heavy elements in stars

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Experimental data help unravel the mystery surrounding the creation of heavy elements in stars


Experimental data help unravel the mystery surrounding the creation of heavy elements in stars
Top: Raw matrix of 𝛾-ray energies and excitation energies following 𝛽 decay of 140Cs. The two diagonal projections for excitation energies 4.0–4.4 MeV are shown as insets together with their fits. Bottom: 𝛾⁢SF extracted in the present work (blue squares) compared to data for 138Ba at higher energies (black, white, and red dots), as well as theoretical models taken from talys1.95. Credit: Physical Review Letters (2024). DOI: 10.1103/PhysRevLett.132.202701

How are stars born, and how do they die? How do they produce the energy that keeps them burning for billions of years? How do they create the elements we observe today? Definitive answers to these questions continue to elude scientists in their quest to understand the processes that shape the chemical makeup of the universe.

Although the exact details of the reaction processes are unclear, understanding where and how elements are formed, and the processes of star formation, is essential for a comprehensive picture of the universe’s history, structure and evolution.

Recently, an international team, including researchers from the U.S. Department of Energy’s (DOE) Argonne National Laboratory, obtained new experimental data that clarifies how some of the heaviest elements in the universe are formed in stars. This discovery begins to answer fundamental questions about our origins.

The findings are published in the journal Physical Review Letters.

In particular, the team obtained the first experimental constraints for measuring the rate of the process in which neutrons collide and merge with a nucleus of the isotope barium-139 to form barium-140. Isotopes are members of a family of an element that all have the same number of protons but different numbers of neutrons. The reaction rate of barium-139 as it turns into barium-140 has been a dominant source of uncertainty in predictive models used to determine the presence of isotopes of heavy elements in stars.

Led by Artemis Spyrou, a professor in the Department of Physics and Astronomy at Michigan State University and the Facility for Rare Isotope Beams (FRIB), and Dennis Mücher, a professor at the Institute for Nuclear Physics at the University of Cologne, Germany, the team benefited from the use of CARIBU, a sophisticated source of radioactive ions located at the Argonne Tandem Linac Accelerator System (ATLAS), a DOE Office of Nuclear Physics user facility at Argonne.

“It is now clear that the synthesis of elements in stars is more complex than previously thought,” said Spyrou. “Only through this type of measurement will we be able to disentangle the contributions from different astrophysical processes.”

Scientists have known for a long time that the heavy elements in stars, such as barium, lanthanum and cesium, are created through rapid and slow nucleosynthesis processes. Nucleosynthesis is the formation of new atomic nuclei—the centers of atoms that are made up of protons and neutrons—or elements, by various processes in the universe.

The rapid or “r” process, which takes place in a matter of seconds, is thought to be responsible for nucleosynthesis in exploding stars, such as supernovae, and the small, dense stars that emerge after their collapse. Conversely, the slow or “s” process is thought to be responsible for nucleosynthesis primarily in brightly burning older stars, nearing the end of life.

Relatively new astronomical observations point to a nucleosynthesis pathway different from the rapid and slow processes. As some stars thought to be poor in metal have shown unusual abundance patterns of certain elements, scientists proposed an intermediate or “i” process to explain this phenomenon.

“What is most fascinating to me is that we find these different elements here on Earth, and often without knowing it, interact with them almost daily,” said Mücher. “However, we still don’t fully understand where they come from. Now, we have a better understanding that the i process is somehow related.”

Enabled by the CARIBU source at ATLAS, scientists have been able to study barium isotopes as they captured neutrons and eventually formed lanthanum—a byproduct of barium-139 decay—and a key indicator of the i process. However, determining this neutron-capture rate is especially challenging because the half-life of barium-139 is only 83 minutes.

With the aid of certain experimental techniques, researchers have found it is possible to indirectly determine this rate with a beam of the isotope cesium-140. This isotope undergoes radioactive decay into barium-140 and in doing so, emits a gamma ray, which researchers were able to detect and measure using FRIB’s Summing Nal (SuN) detector, a total absorption gamma-ray spectrometer. By more accurately capturing data for this process, researchers could indirectly calculate the reaction rate of barium-139 as it turns into barium-140, and the probability that this reaction will produce lanthanum.

“The technique that is being used requires radioactive beams of both fairly high intensity and very high purity,” said ATLAS director Guy Savard, an Argonne Distinguished Fellow. “CARIBU provides these conditions for a whole range of neutron-rich isotopes.”

Equipped with this newfound knowledge, researchers can apply what they’ve discovered in this study to other use cases at CARIBU and its near-future upgrade, nuCARIBU. There, they can further their understanding of how neutron capture works for neutron-rich isotopes in the i process. Eventually, they hope to find a more direct way to study the process.

“In the fall we’ll have a large experimental campaign enabled by nuCARIBU, making a number of measurements again, so we can expand the range over which this technique is applied, and look at many cases and try to understand the systematics of how this neutron capture on the neutron-rich isotopes works,” said Savard. “This is just the first step,” he added.

In addition to Spyrou, Mücher and Savard, authors include P.A. Denissenkov, F. Herwig, E.C. Good, G. Balk, H.C. Berg, D.L. Bleuel, J.A. Clark, C. Dembski, P.A. DeYoung, B. Greaves, M. Guttormsen, C. Harris, A.C. Larsen, S.N. Liddick, S. Lyons, M. Markova, M.J. Mogannam, S. Nikas, J. Owens-Fryar, A. Palmisano-Kyle, G. Perdikakis, F. Pogliano, M. Quintieri, A.L. Richard, D. Santiago-Gonzalez, M.K. Smith, A. Sweet, A. Tsantiri and M. Wiedeking.

More information:
A. Spyrou et al, First Study of the 139Ba(n,γ)140Ba Reaction to Constrain the Conditions for the Astrophysical i Process, Physical Review Letters (2024). DOI: 10.1103/PhysRevLett.132.202701

Citation:
Experimental data help unravel the mystery surrounding the creation of heavy elements in stars (2024, September 12)
retrieved 12 September 2024
from https://phys.org/news/2024-09-experimental-unravel-mystery-creation-heavy.html

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New findings on the extent of golden jackal expansion

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New findings on the extent of golden jackal expansion


New findings on the extent of golden jackal expansion
Golden jackal spotted in Ivalo. Credit: Asta Härkönen

The golden jackal (Canis aureus) has rapidly expanded its range across Europe by thousands of kilometers. It has recently moved into new environments, reaching as far as north of the Arctic Circle in Finland and Norway, and south to the Iberian Peninsula.

Researchers from the University of Oulu, Finland, in collaboration with Polish, Norwegian, and Spanish scientists, have investigated the origin and possible migration routes of three golden jackals found at the frontiers of their range. The study is published in Mammalian Biology.

Genetic analyses revealed that a jackal found in Finland had traveled approximately 2,500 kilometers from the western Pannonian population (located in Austria, Hungary, and Croatia) to Sodankylä. A jackal found in the Tromsø region of Norway had either traveled 1,500 km from the Baltic population or 3,400 km from the Caucasus.

The individual discovered on the Iberian Peninsula likely originated from western Pannonia (1,650 km), although the Adriatic region (1,300 km) is also a possible, though less likely, source. The study shows that golden jackals are expanding into new areas from multiple source populations, including both core areas and recently established regions.

All studied individuals were males and first-generation migrants, meaning they were new arrivals. No evidence of hybridization with domestic dogs was found. The results also supported previous findings of the genetic homogeneity of golden jackals; both the Finnish and Spanish individuals belonged to the most common European maternal lineage.

“Previously, it was assumed that golden jackals arriving in Finland came from the established Baltic population, but this study shows that they can migrate from much further away, even thousands of kilometers. Wolves have also been shown to travel more than a thousand kilometers from their home range,” says Professor Jouni Aspi from the University of Oulu.

According to the researchers, in addition to the individual in Sodankylä, seven confirmed sightings of golden jackals have been made in Finland, the most recent in Ivalo in August 2024.

The study demonstrates that golden jackals are capable of traveling astonishing distances in very different environmental conditions and establishing new packs and populations in extreme climates, highlighting their remarkable resilience and adaptability.

Climate change has been suggested as one of the reasons for their expansion. The species also adapts to cold weather, and it is shown to survive in thick mountain snow.

The golden jackal is larger than a fox but much smaller than a wolf. In Finland, the golden jackal is not an invasive species introduced by humans, but a naturally expanding newcomer species that is protected under the Nature Conservation Act.

Omnivorous, the golden jackal mainly eats small mammals and carrion but also consumes plants, birds, and small ungulates, as well as livestock. It is adept at taking advantage of food sources provided by humans: for instance, the stomach contents of the Sodankylä golden jackal included fish remains likely left behind by local fishermen.

The golden jackal occupies a food chain niche between foxes and wolves, meaning it likely competes with them and raccoon dogs for food and territory.

More information:
Wiesław Bogdanowicz et al, Species on the move: a genetic story of three golden jackals at the expansion front, Mammalian Biology (2024). DOI: 10.1007/s42991-024-00452-0

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New findings on the extent of golden jackal expansion (2024, September 12)
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Elon Musk is on track to become the world’s first trillionaire—it’s a sign markets aren’t working

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Elon Musk is on track to become the world’s first trillionaire—it’s a sign markets aren’t working


monopoly money
Credit: Jan van der Wolf from Pexels

Apparently, the world is about to get its first trillionaire.

A report from the business intelligence agency Informa Connect says, at his present rate of wealth accumulation, tech billionaire Elon Musk is on track to be the world’s first trillionaire, three years from now.

At the moment, Musk is said to be worth US$195 billion (A$293 billion), but if his wealth continues growing at the recent rate of 110% per year, he will hit US$1.195 trillion in 2027.

The next trillionaire after Musk should be Indian mining magnate Gautam Adani, followed by Nvidia chief Jensen Huang and Indonesian mining mogul Prajogo Pangestu, all of whom are on track to hit the milestone in 2028.

The nearly 1 billion human beings who don’t yet have electricity connected to their homes will doubtless be looking on with interest as the tech bros and mining bosses vie to crack 13 digits.

Before examining how it is that someone could ever make a trillion-dollar fortune, and what it might mean for the world for so much of the world’s wealth to be held in the hands of one person, it is important to first try to comprehend how big a trillion actually is.

One trillion seconds last 31,000 years

A million is a big number: it is 1,000 thousands. If you managed to retire with that many dollars in superannuation, you would have saved up more than 90% of your fellow retirees.

One billion is 1,000 millions. It takes 12 days for a million seconds to pass, but 31 years for a billion seconds to tick over.

That means a trillion seconds would equal 31,000 years.

If you had $1 trillion and did no more than stick it in the bank where it earned 4% interest per year you would get $40 billion per year in interest.

No one needs $1 trillion, and it is hard to see how anyone could spend it as fast as it grew, which raises important questions about how societies, economies and democracies will be able to function if and when governments allow trillionaires to emerge.

For mortals, a trillion is hard to justify

France’s King Louis XIV spent today’s equivalent of US$200 billion–300 billion building his palace at Versailles, and it was by no means his only palace.

Pyramids and sphinxes didn’t come cheap either, but these sorts of expenditures were seen as needed for beings selected by gods and not entirely mortal.

For mortals, some believe that the entire population benefits when a small minority controls most of the resources on the basis that it builds incentives.

Just as peasants spent millennia awaiting their reward in the afterlife while their rulers enjoyed heaven on earth, in modern economies we are told wealth and prosperity will trickle down to us eventually if we keep working hard.

Unfortunately for most of us, despite the wealth of the richest 200 Australians growing from A$40.6 billion to $625 billion over the past 20 years, neither the Australian economy nor the wages of ordinary Australians are soaring.

High profits are meant to be temporary

Incentives can and do play an important role in our economy.

In the so-called “free market” envisaged by 18th-century economist Adam Smith, if my new farming technique or silicon chip is so good that everyone wants one, it is considered only fair that I get an initial reward.

But after a while, everyone else will be free to compete with me by selling similar goods and in turn stopping me from getting an extraordinary ongoing reward.

The problem is that some markets aren’t free and don’t work properly. It is no accident that the world’s biggest fortunes are held by those who have monopoly rights to sell natural resources or technologies that are protected by patents or systems that lock in users.

That’s bad news for those still waiting patiently for wealth to trickle down or to be spread more evenly.

Technofeudalism keeps profits growing

In his latest book former Greek finance minister Yannis Varoufakis describes the world we now live in as one of technofeudalism in which online platforms have the ongoing opportunity to exploit workers, consumers and producers in ways Smith could not have imagined.

Having created digital platforms where the price of entry is handing over your personal details and preferences, modern tech titans use a new form of alchemy to convert data into knowledge that allows them to keep you on their platform and exploit you or advertisers or suppliers in the belief that you won’t leave.

And while there are physical limits to how big a car factory or fast-food chain can grow, there are almost no physical limits on how much money tech platforms can make by selling ads they didn’t make for products they didn’t make to consumers they know nearly everything about.

Restraining profits is pro-market

It isn’t anti-capitalist to want those profits competed away, it’s pro-market.

When the United States broke up J.D. Rockerfeller’s oil monopoly in the early 20th century, the oil industry prospered rather than vanished. consumers and the businesses that had dealt with Rockerfeller were better off, and so was the economy as a whole.

Democracies have, for now, the power to use taxes and regulations to redistribute the enormous benefits flowing to the new class of billionaires (and soon trillionaires) from the sale of scarce resources and the creation of platforms that keep us trapped.

Whether and how we use that power is up to us, but we mightn’t have it for long. The more the new class of billionaires and trillionaires becomes entrenched, the more it will be able to use the political system to protect their interests rather than those of mere mortals.

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Opinion: Elon Musk is on track to become the world’s first trillionaire—it’s a sign markets aren’t working (2024, September 12)
retrieved 12 September 2024
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