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Solving a memristor mystery to develop efficient, long-lasting memory devices

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Solving a memristor mystery to develop efficient, long-lasting memory devices


Solving a memristor mystery to develop efficient, long-lasting memory devices
Graphical abstract. Credit: Matter (2024). DOI: 10.1016/j.matt.2024.07.018

Phase separation, when molecules part like oil and water, works alongside oxygen diffusion to help memristors—electrical components that store information using electrical resistance—retain information even after the power is shut off, according to a University of Michigan led study recently published in Matter.

Up to this point, explanations have not fully grasped how memristors retain information without a power source, known as nonvolatile memory, because models and experiments do not match up.

“While experiments have shown devices can retain information for over 10 years, the models used in the community show that information can only be retained for a few hours,” said Jingxian Li, U-M doctoral graduate of materials science and engineering and first author of the study.

To better understand the underlying phenomenon driving nonvolatile memristor memory, the researchers focused on a device known as resistive random access memory or RRAM, an alternative to the volatile RAM used in classical computing, and the findings are particularly promising for energy-efficient artificial intelligence applications.

The specific RRAM studied, a filament-type valence change memory (VCM), sandwiches an insulating tantalum oxide layer between two platinum electrodes. When a certain voltage is applied to the platinum electrodes, a conductive filament forms a tantalum ion bridge passing through the insulator to the electrodes, which allows electricity to flow, putting the cell in a low resistance state representing a “1” in binary code. If a different voltage is applied, the filament is dissolved as returning oxygen atoms react with the tantalum ions, “rusting” the conductive bridge and returning to a high resistance state, representing a binary code of “0.”

It was once thought that RRAM retains information over time because oxygen is too slow to diffuse back. However, a series of experiments revealed that previous models had neglected the role of phase separation.

“In these devices, oxygen ions prefer to be away from the filament and will never diffuse back, even after an indefinite period of time. This process is analogous to how a mixture of water and oil will not mix, no matter how much time we wait, because they have lower energy in a de-mixed state,” said Yiyang Li, U-M assistant professor of materials science and engineering and senior author of the study.

To test retention time, the researchers sped up experiments by increasing the temperature. One hour at 250°C is equivalent to about 100 years at 85°C—the typical temperature of a computer chip.

Using the extremely high-resolution imaging of atomic force microscopy, the researchers imaged filaments, which measure only about five nanometers or 20 atoms wide, forming within the one micron wide RRAM device.

“We were surprised that we could find the filament in the device. It’s like finding a needle in a haystack,” Li said.

The research team found that different sized filaments yielded different retention behavior. Filaments smaller than about 5 nanometers dissolved over time, whereas filaments larger than 5 nanometers strengthened over time. The size-based difference cannot be explained by diffusion alone.

Together, experimental results and models incorporating thermodynamic principles showed the formation and stability of conductive filaments depend on phase separation.

The research team leveraged phase separation to extend memory retention from one day to well over 10 years in a rad-hard memory chip—a memory device built to withstand radiation exposure for use in space exploration.

Other applications include in-memory computing for more energy efficient AI applications or memory devices for electronic skin—a stretchable electronic interface designed to mimic the sensory capabilities of human skin. Also known as e-skin, this material could be used to provide sensory feedback to prosthetic limbs, create new wearable fitness trackers or help robots develop tactile sensing for delicate tasks.

“We hope that our findings can inspire new ways to use phase separation to create information storage devices,” Li said.

Researchers at Ford Research, Dearborn; Oak Ridge National Laboratory; University at Albany; NY CREATES; Sandia National Laboratories; and Arizona State University, Tempe contributed to this study. The device was built at the Lurie Nanofabrication Facility and studied at the Michigan Center for Materials Characterization.

More information:
Jingxian Li et al, Thermodynamic origin of nonvolatility in resistive memory, Matter (2024). DOI: 10.1016/j.matt.2024.07.018

Citation:
Solving a memristor mystery to develop efficient, long-lasting memory devices (2024, September 10)
retrieved 10 September 2024
from https://techxplore.com/news/2024-09-memristor-mystery-efficient-memory-devices.html

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Apple’s iPhone 16 launch shows AI is shaking up the tech giant’s core market

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Apple’s iPhone 16 launch shows AI is shaking up the tech giant’s core market


apple building
Credit: Siva Seshappan from Pexels

As someone who helped set up one of the first iPhones back in late 2007 on live TV, I found the launch of the first iteration of Apple’s smartphone an exciting time. At the launch in June of that year, a grinning Steve Jobs proudly held up that early device to the obvious delight of Apple fans.

Did the late Apple founder know then that he would change the future of mobile communication forever? That breakthrough device was revolutionary, transforming the way people interact with each other.

At a launch event on Monday September 9, Apple released details of its new iPhone 16, along with several other new products such as the Apple Watch Series 10 and Air Pods 4. The unveiling of the iPhone 16 could mark a turning point in the history of Apple’s smartphone brand.

Back in 2007, there were no other players in the market. Today, competition is fierce and there is a new factor in the mix that has the potential to shake up the smartphone market in the long term—artificial intelligence (AI).

The much vaunted new features based on AI are being marketed under the banner of “Apple Intelligence.” These include features for photo and video editing—something that other companies have made much of when launching new smartphones this year, such Google’s Pixel 9—but also features to help you edit text and generate your own AI images.

Since the release of the original iPhone, there have been a lot of changes at Apple. Jobs died in 2011 but his successor as CEO, Tim Cook, has provided a solid strategic direction for the company. Jony Ive, the industrial design guru behind many of Apple’s most famous products left the company in 2019 to set up his own design company, LoveFrom.

There have been more than 40 iterations of the iPhone, with variants that include the regular version, the Plus, Pro and Pro Max versions. Over 50% of Apple’s total revenue is generated by sales of the device.

As such, it still forms the cornerstone of the company’s business, which now includes associated products such as the aforementioned AirPods and watches. There’s also the Apple Vision Pro, a “mixed reality” headset which layers digital elements over a view of the real world. Other sectors of Apple’s business now include cloud storage along with TV and filmmaking.

However, Samsung, Google, OnePlus, Xiaomi and an abundance of other players in the smartphone market are all vying to find a place in your pocket for their smartphone. With such fierce competition in the phone market, Apple—and those other companies—have previously concentrated on improvements to the features they already offer.

That means faster processors, longer battery life with faster charge times, improved camera technology, larger storage capacity, better WiFi and Bluetooth, instant payment technology and more robust, titanium cases with near indestructible screens.

However, there is now a rush to incorporate AI into phones and indeed into other Apple devices. This is not an area that has been emphasized to the consumer much before now, but Apple has recently begun heavily trailing its Apple Intelligence features.

Google and Samsung have also made much of AI features in launches for their smartphones this year. So could AI be a game changer in a market that has until now been all about incremental improvements?

As a researcher into AI, I spent this summer looking at the features of this technology, which of course has been around for many years. We have now reached a point in the development of AI where it will undoubtedly change the way we work and live.

The new iPhone 16 with Apple Intelligence will offer a number of AI-based tools to enhance the user experience. This will include proofreading, rewriting, and summarizing text, an enhanced ability to detect objects in images and videos, such as faces and descriptions. It will also include the ability to generate images by describing what you want to create in a text or voice prompt, image editing features and the ability to create personalized emojis.

One intriguing AI-enabled feature is called Visual Intelligence. This allows you to search for content on whatever you can see through your phone with the help of a new camera control button on the side of the iPhone 16. One of the examples given during Apple’s Monday launch event was the ability to take a photo of a restaurant and instantly pull up opening hours, a menu and ratings, without having to manually input that information into a search engine.

Users could also take a photo of a poster for an event they see in the street. The iPhone 16 will automatically add it to their calendar, along with other details such as the time and location.

There will also be important AI-based improvements to Apple’s digital assistant technology, Siri. The assistant will better understand and respond to complex requests, perform actions within apps more seamlessly, better understand content from apps and provide more relevant information.

Additionally, Siri is expected to have a better understanding of user behavior and be able to make suggestions, offer intelligent replies as options in messages and record and transcribe phone calls.

These new features will be an exciting addition to the AI features already making their way into other smartphones. For example, Samsung has a live language translation feature within calls, which can give human translators a run for their money.

Provided by
The Conversation


This article is republished from The Conversation under a Creative Commons license. Read the original article.The Conversation

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Apple’s iPhone 16 launch shows AI is shaking up the tech giant’s core market (2024, September 10)
retrieved 10 September 2024
from https://techxplore.com/news/2024-09-apple-iphone-ai-tech-giant.html

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Surprising hormone-related gene activity discovered in the early larval stage of the Malabar grouper

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Surprising hormone-related gene activity discovered in the early larval stage of the Malabar grouper


Surprising hormone-related gene activity discovered in the early larval stage of the Malabar grouper
A Malabar grouper at OIST’s Marine Science Station. Scientists reveal a unique activation of thyroid and corticoid genes in the early larval stage of these fish—a phenomenon never observed in any fish species before. Credit: Merle Naidoo, OIST

Researchers at the Okinawa Institute of Science and Technology (OIST)’s Marine Climate Change Unit and Marine Eco-Evo-Devo Unit have highlighted patterns of gene activation during Malabar grouper larval development, revealing an unusual early peak of activation of thyroid and corticoid genes during the early larval stage of these fish.

Their paper, published in the journal eLife, is the first study to show that thyroid and corticoid genes are activated twice during larval development, once during the early larval stage and once during metamorphosis. This early activation has never been encountered in any fish species before, making the grouper case unique.

Groupers are meso-predators playing a crucial role in maintaining the balance and health of marine ecosystems. The Malabar grouper (Epinephelus malabaricus), known as Yaito-hata in Japanese, can grow up to 2 meters in length.

However, their popularity and high economic value on the food market has led to overexploitation, with many species at risk of extinction. In response to this threat and to meet continued demand, grouper aquaculture farms have been established in Okinawa and other places in the world.

Grouper aquaculture in Okinawa

“For me, the eco-culture aspect of this study was especially interesting; that these fish are being bred and sold here in Okinawa,” Dr. Roger Huerlimann, lead author and molecular biologist in the Marine Climate Change Unit, said.

Research on breeding and raising young Malabar groupers began at the Ishigaki branch of the Okinawa Prefectural Fisheries and Ocean Research Center in 1992. The first successful breeding in Okinawa occurred in 1996. By 1997, the center had achieved the world’s first large-scale breeding success, producing more than 200,000 young fish. Currently, approximately 10 Malabar grouper fish farms operate in Okinawa.

RNA analysis reveals unusual hormone activation

A genome is the complete set of genetic material in an organism. Scientists can study how a genome functions by examining the RNA produced by the genome under specific conditions or in certain cells—a process called transcriptomic analysis. This allows them to identify which genes are activated at specific times during different developmental stages.

The researchers examined how genes related to thyroid and corticoid hormones, as well as other biological processes, are expressed in the Malabar grouper during its larval development, which includes a very important step: metamorphosis.

After hatching, the larvae drift in the open ocean for about 60 days, before coming back to coastal environments. During this amazing journey, they experience a dramatic hormone-driven metamorphosis, including the regression of spines and the appearance of an adult-like pigmentation.

Surprising hormone-related gene activity discovered in the early larval stage of the Malabar grouper
Credit: Adapted from eLife (2024). DOI: 10.7554/eLife.94573.3

“Our genomic analysis clearly shows a high activation of thyroid and corticoid genes at the timing of metamorphosis. In groupers, metamorphosis corresponds with the appearance of an adult-like pigmentation and the disappearance of spines that the larvae have on the dorsal and pectoral fins,” Dr. Huerlimann explained.

“What was interesting is that we also found a surge in these genes at the very beginning of the larval development, which we’ve not seen before in other fish species.”

Dr. Natacha Roux, a researcher at Centre de Recherches Insulaires et Observatoire de l’Environnement (CRIOBE) and former researcher in the Computational Neuroethology Unit at OIST, elaborated, “We also measured thyroid hormone and corticoid levels in the larvae and saw an increase of both hormones at the beginning of the larval development, confirming the genomic analysis results.

“The reason of this activation is not known yet, but we hypothesize it may be linked to the development of larval spines, potentially helping in buoyancy and predator deterrence.”

Both researchers emphasized that their findings were directly tied to the Motobu Town community’s willingness to open their doors to the scientists, without which the project would not have been possible. This allowed the research team to set up a small laboratory in the Okinawa Prefectural Sea Farming Center for sampling and experiments.

Dr. Huerlimann aims to support sustainable aquaculture in Okinawa by helping local aquaculture farmers through his research. “Initially, our goal was to create a reference genome sequence as a foundation for further research,” he explained.

“But in the past three years, I’ve gone around talking to farmers to understand their challenges. Disease management is a significant issue, so I want to see how my research can help address this and other issues they face.”

More information:
Roger Huerlimann et al, The transcriptional landscape underlying larval development and metamorphosis in the Malabar grouper (Epinephelus malabaricus), eLife (2024). DOI: 10.7554/eLife.94573.3

Journal information:
eLife


Citation:
Surprising hormone-related gene activity discovered in the early larval stage of the Malabar grouper (2024, September 10)
retrieved 10 September 2024
from https://phys.org/news/2024-09-hormone-gene-early-larval-stage.html

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Two editing tricks can help companies boost investor confidence

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Two editing tricks can help companies boost investor confidence


investor
Credit: CC0 Public Domain

A new study finds there are two simple editing changes companies can make to their annual reports that improve investor confidence.

At issue are so-called “material weaknesses in internal control.” Internal controls are practices that prevent companies from inadvertently misrepresenting any aspect of their finances in their public-facing financial statements. Material weaknesses in internal controls refer to any problems that make the internal control system less effective.

“Material weaknesses in internal controls are bad news for investors, who rely on financial statements to make investment decisions,” says Joe Brazel, co-author of a paper on the work and Jenkins Distinguished Professor of Accounting in North Carolina State University’s Poole College of Management.

“That’s why the Sarbanes-Oxley Act requires companies to disclose the effectiveness of their internal controls. For this study, we wanted to see if the language companies use when making those disclosures has an effect on how investors respond.”

“Specifically, we wanted to look at two things,” Brazel says. “First, how do investors respond when companies are defensive when disclosing material weaknesses, compared to taking more accountability for the weaknesses? Second, how do investors respond when companies use first-person pronouns when discussing material weaknesses, as opposed to referring specifically to management?”

For the study, the researchers first analyzed 200 internal control reports from publicly traded companies to assess the language they used when disclosing material weaknesses. This allowed the researchers to determine which communications approaches were most common. The researchers then enlisted 96 MBA students to serve as investors for an experiment designed to assess how investors respond to various communication approaches.

The researchers found that the most common approach among publicly traded companies was to use defensive language in conjunction with first-person pronouns.

“What’s striking is that this is the exact opposite of what our experiment found to be the most effective communication approach,” Brazel says.

The experiment found that nonprofessional investors are more willing to invest in a company when management doesn’t use first-person pronouns and takes a less defensive position.

“Study participants responded better to internal control reports that said management is aware of the limitations that internal controls have and are developing safeguards to reduce those limitations,” Brazel says.

“Prior communications research tells us that being defensive when conveying bad news can actually exacerbate the negative response in stakeholders,” says Brazel. “And by using first person pronouns—we, us, our—more of the blame is placed on management.

“On the other hand, being less defensive improves the stakeholder response. And—perhaps ironically—explicitly referencing management, rather than using first-person pronouns, limits the extent to which any negative response is associated with the managers.

“The takeaway here is that the words we use matter a great deal,” says Brazel. “And given that we’re talking about how reports are phrased, this is a very low-cost intervention that companies can use to improve investor confidence.”

The paper, “Management’s Communication Style when Disclosing Material Weaknesses in Internal Control,” is published in the journal Accounting Horizons.

More information:
Joseph F. Brazel et al, Management’s Communication Style When Disclosing Material Weaknesses in Internal Control, Accounting Horizons (2024). DOI: 10.2308/HORIZONS-2023-007

Citation:
Two editing tricks can help companies boost investor confidence (2024, September 10)
retrieved 10 September 2024
from https://phys.org/news/2024-09-companies-boost-investor-confidence.html

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Stretchable, wearable device lights up an LED using only the warmth of skin

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Stretchable, wearable device lights up an LED using only the warmth of skin


Stretchable, wearable device lights up an LED using only the warmth of skin
Credit: University of Washington

One of the drawbacks of fitness trackers and other wearable devices is that their batteries eventually run out of juice. But what if in the future, wearable technology could use body heat to power itself?

UW researchers have developed a flexible, durable electronic prototype that can harvest energy from body heat and turn it into electricity that can be used to power small electronics, such as batteries, sensors or LEDs. This device is also resilient—it still functions even after being pierced several times and then stretched 2,000 times.

The team detailed these prototypes in a paper published Aug. 30 in Advanced Materials.

“I had this vision a long time ago,” said senior author Mohammad Malakooti, UW assistant professor of mechanical engineering. “When you put this device on your skin, it uses your body heat to directly power an LED. As soon as you put the device on, the LED lights up. This wasn’t possible before.”

Traditionally, devices that use heat to generate electricity are rigid and brittle, but Malakooti and team previously created one that is highly flexible and soft so that it can conform to the shape of someone’s arm.

This device was designed from scratch. The researchers started with simulations to determine the best combination of materials and device structures and then created almost all the components in the lab.






Credit: University of Washington

It has three main layers. At the center are rigid thermoelectric semiconductors that do the work of converting heat to electricity. These semiconductors are surrounded by 3D-printed composites with low thermal conductivity, which enhances energy conversion and reduces the device’s weight.

To provide stretchability, conductivity and electrical self-healing, the semiconductors are connected with printed liquid metal traces. Additionally, liquid metal droplets are embedded in the outer layers to improve heat transfer to the semiconductors and maintain flexibility because the metal remains liquid at room temperature. Everything except the semiconductors was designed and developed in Malakooti’s lab.

In addition to wearables, these devices could be useful in other applications, Malakooti said. One idea involves using these devices with electronics that get hot.

“You can imagine sticking these onto warm electronics and using that excess heat to power small sensors,” Malakooti said. “This could be especially helpful in data centers, where servers and computing equipment consume substantial electricity and generate heat, requiring even more electricity to keep them cool.

“Our devices can capture that heat and repurpose it to power temperature and humidity sensors. This approach is more sustainable because it creates a standalone system that monitors conditions while reducing overall energy consumption. Plus, there’s no need to worry about maintenance, changing batteries or adding new wiring.”

These devices also work in reverse, in that adding electricity allows them to heat or cool surfaces, which opens up another avenue for applications.

“We’re hoping someday to add this technology to virtual reality systems and other wearable accessories to create hot and cold sensations on the skin or enhance overall comfort,” Malakooti said. “But we’re not there yet. For now, we’re starting with wearables that are efficient, durable and provide temperature feedback.”

More information:
Youngshang Han et al, 3D Soft Architectures for Stretchable Thermoelectric Wearables with Electrical Self‐Healing and Damage Tolerance, Advanced Materials (2024). DOI: 10.1002/adma.202407073

Citation:
Stretchable, wearable device lights up an LED using only the warmth of skin (2024, September 10)
retrieved 10 September 2024
from https://techxplore.com/news/2024-09-stretchable-wearable-device-warmth-skin.html

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part may be reproduced without the written permission. The content is provided for information purposes only.





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