Back in November, Google announced that Gmail would directly show package and delivery tracking in your inbox. If this feature isn’t live yet, you can manually enable it in Gmail settings.
This new Gmail package tracking shows when a delivery is arriving directly in the inbox view underneath an email. There’s a truck icon and “Arriving [date]” in green.
Additionally, Gmail has redesigned the information that appears when you open a message. It’s now housed in a card with Dynamic Color used for the background. In the top-left corner you get an image preview, name, and delivery date (“From the carrier”) again. You might also see a store-specific “Order number” with the ability to quickly copy. Underneath that is an order timeline with shortcuts to “Track package” on the web and “Order details.”
Compared to the previous design, you actually see less information with “Items” truncated if you have multiple items.
When this feature was announced in early November, Google said it was rolling out on Android and iOS in the coming weeks. Once available, there’d be a “Track your packages in Gmail” card at the top of your inbox.
For those that haven’t been prompted by the card, you can (on Android) open Gmail Settings from the navigation drawer > select your email address > scroll to “General” > Package tracking — “Google will share tracking numbers for your packages with shipping carriers. You’ll get status updates here in Gmail.”
On iOS, open the redesigned settings and scroll to “Data privacy” near the bottom.
You can disable it if you prefer the old view, while Google plans to “proactively show a delay label and bring the email to the top of your inbox” in the coming months. It’s also coming to Gmail on the web.
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In his cult classic “Ender’s Game”, Orson Scott Card imagined a world in which Earth’s brightest, and tragically youngest, tacticians could command armies across vast distances instantaneously using a device called the ansible.
While the jury is still out on whether such a device will ever be possible, scientists at the US Department of Energy’s (DoE) Brookhaven National Laboratory this week detailed a “never-before-seen” type of quantum entanglement they say could one day enable powerful new communications tools and computers.
Scientists have been trying to harness quantum-entangled particles ever since the phenomenon was theorized in the early 20th century and the topic has been a source of heated debate among physicists for decades. However, late last year, three scientists — Alain Aspect, John Clauser, and Anton Zeilinger — were awarded the Nobel Prize in Physics for their work on quantum entanglement.
A ‘new’ kind of quantum entanglement
Brookhaven’s latest discovery was made while exploring a novel means of probing the inner workings of atomic nuclei. The experiments, described in the journal Science Advances, used Brookhaven’s Relativistic Heavy Ion Collider to accelerate particles at nearly the speed of light.
Usually, the collider would smash the gold particles together. This would melt the boundaries between protons and neutrons and allow scientists to study the quarks and gluons — two of the elementary particles that form the nucleus of atoms — in an environment similar to that of the earliest moments of the galaxy.
But instead of smashing them together, the gold particles were surrounded by a cloud of photons and allowed to pass by each other.
According to Brookhaven, as they passed each other, a series of quantum fluctuations caused by the interaction between photons and gluons produced a new particle that quickly decayed into a pair of charged pions. When measured, these pions allowed scientists to map the distributions of gluons within the atom’s nucleus.
In a blog post, Daniel Brandenburg, a member of the STAR collaboration who worked on the project, said the technique works a bit like a scan at a doctor’s office, but instead of seeing inside a patient’s brain, scientists are peering into the inner workings of protons.
It was while taking these measurements that scientists say they observed a curious phenomenon — a new kind of quantum interference.
“We measure two outgoing particles and clearly their charges are different — they are different particles — but we see interference patterns that indicate these particles are entangled or in sync with one another, even though they are distinguishable particles,” Zhangbu Xu, a physicist at Brookhaven National Labs said in the blog post.
According to Brookhaven, most other observations of entanglement have been between photons or identical electrons. “This is the first-ever experimental observation of entanglement between dissimilar particles,” Brandenburg claims.
What are the Russians looking for?
Brookhaven was one of three DoE national labs targeted by Russian hackers over the summer.
According to Reuters, between August and September, a group of cybercriminals known as Cold River used phishing emails and fabricated log-in pages to harvest employee credentials from Brookhaven, Argonne, and Lawrence Livermore National Laboratories.
The facilities are home to a variety of nuclear research programs including several related to the maintenance and development of the US strategic stockpile.
While Reuters was able to confirm Cold River’s involvement with the help of five cybersecurity experts using digital fingerprints associated with the group, it was unable to determine whether the hackers were able to breach the DoE’s defenses.
Cold River has had previous success compromising high-profile targets. One of the group’s more recent targets was Richard Dearlove, the former head of Britain’s foreign intelligence service MI6, whose emails were leaked in May.
A prelude to the quantum internet
The DoE’s various national labs have been digging into quantum mechanics including practical applications of quantum entanglement for years now and has invested millions of dollars into the development of the quantum internet.
While no ansible, quantum networks take advantage of properties of particles to encode data more efficiently than is possible using the binary ones and zeros used in traditional computing. At least that’s the idea, anyway.
While efforts to build quantum networks are still in their infancy, several experiments have shown promise. In 2019, Brookhaven demonstrated the transfer of entangled photons over a fiber network stretching approximately 11 miles. At the time, it was the longest-distance quantum entanglement experiment to take place in the US.
More recently, researchers in the Netherlands showed the transmission of quantum information using an intermediary node, a feature they say is essential to enabling the quantum internet. ®
Chrome is a popular browser for a reason: It’s fast, powerful, and compatible with popular apps, services, and extensions. All that power, though, comes from somewhere, and ends up putting a strain on your RAM. Chrome is a memory hog. Fortunately, there’s now an easy solution to the problem.
Why does Chrome use so much memory?
Each tab you open is a new activity for Chrome to manage, and the browser makes a point of running each tab as its own process. That way, something can go wrong with one tab without affecting others. Chrome is also fast because of its prerendering feature, which takes up RAM to keep things loading as quickly as possible. Plus, the more tabs you open—and the most resource-intensive tasks you run in those tabs—the more RAM you’ll use.
It isn’t really an issue until it becomes one: If your system runs out of RAM, you run into performance issues, all because your internet browser can’t handle its RAM properly.
How Memory Saver can preserve RAM when using Chrome
Thankfully, Google has addressed these issues with a new feature called “Memory Saver.” With it, Chrome will automatically make unused tabs inactive while you’re working in other tabs. When you return to these inactive tabs, Chrome will turn them back on. According to the company, Memory Saver can use up to 30% less memory than running Chrome without it, which should solve most memory issues with the browser.
Memory Saver isn’t the only new “Performance” feature coming to Chrome. Google also introduced an “Energy Saver” feature as well, which reduces performance to preserve battery life, as essential for those of us who work on laptops.
How to use Memory Saver to free up RAM in Chrome
Memory Saver is officially rolling out to users over the next few weeks, however it’s available as a feature flag right now. Flags are “experimental features” Chrome tucks away from most users; some aren’t finished yet, which means they could have detrimental effects on your browser. However, since Memory Saver is nearly here, it seems like a safe flag to enable.
To check it out, paste the following link into your address bar, then hit enter: chrome://flags/#high-efficiency-mode-available. Here, click “Default,” choose “Enabled,” then click “Relaunch.” When Chrome restarts, head to Settings, and you’ll notice a new “Performance” tab on the left side of the screen where “Memory Saver” now lives. Click the slider to turn on the feature. If there are sites you’d prefer Chrome always keep active, you can click “Add” to add them to the list. Any time you return to a tab that was inactive, Chrome will let you know and tell you how much RAM it saved by making it inactive.
Two photons propagating in a waveguide interacting with a single quantum emitter. The photon-photon interaction, which results in correlations. Credit: Le Jeannic et al.
Photons, particles that represent a quantum of light, have shown great potential for the development of new quantum technologies. More specifically, physicists have been exploring the possibility of creating photonic qubits (quantum units of information) that can be transmitted over long distances using photons.
Despite some promising results, several obstacles still need to be overcome before photonic qubits can be successfully implemented on a large-scale. For instance, photons are known to be susceptible to propagation loss (i.e., a loss of energy, radiation, or signals as it travels from one point to another) and do not interact with one another.
Researchers at University of Copenhagen in Denmark, Instituto de Física Fundamental IFF-CSIC in Spain, and Ruhr-Universität Bochum in Germany have recently devised a strategy that could help to overcome one of these challenges, namely the lack of photon-photon interactions. Their method, presented in a paper published in Nature Physics, could eventually aid the development of more sophisticated quantum devices.
“We have been working on the deterministic interfacing of single quantum emitters (quantum dots) to single photons for over 15 years and have developed a very powerful method based on nanophotonic waveguides,” Peter Lodahl, one of the researchers who carried out the study, told Phys.org. “We generally applied these devices for deterministic single-photon sources and multi-photon entanglement sources, but another possible application would be to induce nonlinear operations on photons.”
Lodahl and his colleagues realized the first proof-of-concept demonstration of nonlinear operations using individual photons back in 2015. When they investigated this effect further, however, they encountered difficulties in thoroughly understanding the fundamental physics underlying this complex, single-photon and nonlinear interaction.
“In our previous work, we found that the physics governing the nonlinear interaction of pulses of light was remarkably rich and gave rise to some novel opportunities for constructing photonic quantum gates and photon sorters,” Lodahl said. “We have carried out the first experimental study of nonlinear quantum pulses undergoing nonlinear interaction due to the coupling with a deterministically coupled quantum emitter.”
In their new experiment, the researchers used the efficient and coherent coupling of a single quantum emitter with a nanophotonic waveguide to enable nonlinear quantum interactions between single-photon wave packets. To do this, they used a single quantum dot, a nm-sized particle that behaves like a two-level atom, which was embedded in a photonic crystal waveguide.
“In such systems, the coupling is deterministic, so that even one photon launched into the waveguide is interacting with the quantum dot,” Lodahl explained. “Sending in pulses containing two or more photons induce quantum correlations since only one photon at a time can interact with the quantum dot. By controlling the duration of the quantum pulse, we can tailor these correlations, and the interaction between the photons.”
Using their experimental method, Lodahl and his colleagues were essentially able to control a photon using a second photon, which was mediated by their quantum emitter. In other words, they successfully realized a nonlinear photon-photon interaction.
“We developed a method to get photons to efficiently interact with each other mediated by the coupling to quantum dots,” Lodahl said. “We think this could open new directions for making photon-photon quantum gates (which is the difficult gate in photonic quantum computing) or deterministic photon sorter devices that are essential, e.g., for quantum repeaters.”
The new strategy introduced by this team of researchers could have important implications for both quantum physics research and the development of quantum technology. For instance, their method could open new possibilities for the development of quantum optical devices, while also allowing physicists to experiment with tailored complex photonic quantum states.
“We have a range of activities that extend the present work,” Hanna Le Jeannic, another researcher involved in the study, told Phys.org. “On a fundamental level, we are looking at understanding more deeply how quantum states of light are affected by traveling through a single quantum dot. But we are also already foreseeing applications of this quantum interaction.”
At the moment, Lodahl, Le Jeannic and their colleagues are trying to exploit the nonlinear photon-photon interaction realized in their recent study to simulate the vibrational dynamics of molecules. This could be achieved by mapping the vibrational dynamics of complex molecules onto the propagation of photons in advanced photonic circuits.
Tailored single photons: Optical control of photons as the key to new technologies
More information:
Hanna Le Jeannic et al, Dynamical photon–photon interaction mediated by a quantum emitter, Nature Physics (2022). DOI: 10.1038/s41567-022-01720-x
Ravitej Uppu et al, Quantum-dot-based deterministic photon–emitter interfaces for scalable photonic quantum technology, Nature Nanotechnology (2021). DOI: 10.1038/s41565-021-00965-6
A. Javadi et al, Single-photon non-linear optics with a quantum dot in a waveguide, Nature Communications (2015). DOI: 10.1038/ncomms9655
Citation:
A new method to enable efficient interactions between photons (2022, October 6)
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from https://phys.org/news/2022-10-method-enable-efficient-interactions-photons.html
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Apple has several new features to the Weather application for iPhone with the new iOS 16 operating system. Along with improving the existing features in the app and adding some new features, the company has also added an option that gives alters for severe weather for a particular location.
When this new Severe Weather feature is enabled, the application sends a notification if there’s a severe weather alert issued near the user’s location, enabling to get information for major rain storms, floods, hurricanes, heat waves, tornados, and more.
In this step-by-step guide, we will show you how to quickly and easily enable the Severe Weather notifications on your Apple iPhone running the latest iOS 16 operating system.
How to enable Severe Weather Notifications on Apple iPhone
Step 1: Open the Weather application on your Apple iPhone.
Step 2: Tap on the three-line button at the bottom right corner of the forecast screen.
Step 3: On the page that opens, tap on the three-dot button at the top-right corner and select “Notifications” from the drop-down options.
Step 4: After that, under the Current Location section, enable the toggle switch for the “Severe Weather” option.
Step 5: Tap on the “Allow” button when the confirmation prompt shows up on the screen, and then tap the “Done” button.
That’s it. Once you have followed the above-mentioned step-by-step guide, then you have successfully enabled the Severe Weather notifications on your Apple iPhone running the latest iOS 16 operating system. You also get the option to enable the notifications for other locations as well by simply enabling the toggle switch for those locations.
When you have the Severe Weather notification feature enabled, then the Critical Weather Alerts always play a sound and appear on the Lock Screen even when you have muted the phone or have the Do Not Disturb feature enabled on your iPhone.
Without Egg, Sperm or Womb: Synthetic Mouse Embryo Models Created Solely from Stem Cells
An egg meets a sperm – that’s a necessary first step in life’s beginnings. In embryonic development research, it’s also a common first step. However, in a new study published on August 1, 2022, in the journal Cell, researchers from the Weizmann Institute of Science have grown synthetic embryo models of mice outside the womb by starting solely with stem cells cultured in a petri dish. That means they are grown without the use of fertilized eggs. This method opens new horizons for studying how stem cells form various organs in the developing embryo. It may also one day make it possible to grow tissues and organs for transplantation using synthetic embryo models.
A video showing a synthetic mouse embryo model on day 8 of its development; it has a beating heart, a yolk sac, a placenta, and emerging blood circulation.
“The embryo is the best organ-making machine and the best 3D bioprinter – we tried to emulate what it does,” says Prof. Jacob Hanna of Weizmann’s Molecular Genetics Department, who headed the research team.
Hanna explains that scientists already know how to restore mature cells to “stemness.” In fact, pioneers of this cellular reprogramming won a Nobel Prize in 2012. However, going in the opposite direction, that is, causing stem cells to differentiate into specialized body cells, not to mention form entire organs, has proved far more difficult.
“Until now, in most studies, the specialized cells were often either hard to produce or aberrant, and they tended to form a mishmash instead of well-structured tissue suitable for transplantation. We managed to overcome these hurdles by unleashing the self-organization potential encoded in the stem cells.”
(Left to right): Dr. Noa Novershtern, Prof. Jacob Hanna, Alejandro Aguilera-Castrejon, Shadi Tarazi and Carine Joubran. Credit: Weizmann Institute of Science
Hanna’s team built on two previous advances in his lab. One was an efficient method for reprogramming stem cells back to a naïve state – that is, to their earliest stage – when they have the greatest potential to specialize into different cell types. The other, described in a scientific paper in Nature in March 2021, was the electronically controlled device the team had developed over seven years of trial and error for growing natural mouse embryos outside the womb. The device keeps the embryos bathed in a nutrient solution inside of beakers that move continuously, simulating the way nutrients are supplied by material blood flow to the placenta, and closely controls oxygen exchange and atmospheric pressure. In the earlier research, the team had successfully used this device to grow natural mouse embryos from day 5 to day 11.
This is how synthetic mouse embryo models were grown outside the womb: a video showing the device in action. Continuously moving beakers simulate the natural nutrient supply, while oxygen exchange and atmospheric pressure are tightly controlled.
In the new study, the team set out to grow a synthetic embryo model solely from naïve mouse stem cells that had been cultured for years in a petri dish, dispensing with the need for starting with a fertilized egg. This approach is extremely valuable because it could, to a large extent, bypass the technical and ethical issues involved in the use of natural embryos in research and biotechnology. Even in the case of mice, certain experiments are currently unfeasible because they would require thousands of embryos, whereas access to models derived from mouse embryonic cells, which grow in lab incubators by the millions, is virtually unlimited.
“The embryo is the best organ-making machine and the best 3D bioprinter – we tried to emulate what it does.”
Before placing the stem cells into the device, the researchers separated them into three groups. In one, which contained cells intended to develop into embryonic organs themselves, the cells were left as they were. Cells in the other two groups were pretreated for only 48 hours to overexpress one of two types of genes: master regulators of either the placenta or the yolk sac. “We gave these two groups of cells a transient push to give rise to extraembryonic tissues that sustain the developing embryo,” Hanna says.
Development of synthetic embryo models from day 1 (top left) to day 8 (bottom right). All their early organ progenitors had formed, including a beating heart, an emerging blood circulation, a brain, a neural tube, and an intestinal tract. Credit: Weizmann Institute of Science
Soon after being mixed together inside the device, the three groups of cells convened into aggregates, the vast majority of which failed to develop properly. But about 0.5 percent – 50 of around 10,000 – went on to form spheres, each of which later became an elongated, embryo-like structure. Since the researchers had labeled each group of cells with a different color, they were able to observe the placenta and yolk sacs forming outside the embryos and the model’s development proceeding as in a natural embryo. These synthetic models developed normally until day 8.5 – nearly half of the mouse 20-day gestation – at which stage all the early organ progenitors had formed, including a beating heart, blood stem cell circulation, a brain with well-shaped folds, a neural tube and an intestinal tract. When compared to natural mouse embryos, the synthetic models displayed a 95 percent similarity in both the shape of internal structures and the gene expression patterns of different cell types. The organs seen in the models gave every indication of being functional.
Day 8 in the life of a mouse embryo: a synthetic model (top) and a natural embryo (bottom). The synthetic models displayed a 95 percent similarity in both the shape of internal structures and the gene expression patterns of different cell types. Credit: Weizmann Institute of Science
For Hanna and other stem cell and embryonic development researchers, the study presents a new arena: “Our next challenge is to understand how stem cells know what to do – how they self-assemble into organs and find their way to their assigned spots inside an embryo. And because our system, unlike a womb, is transparent, it may prove useful for modeling birth and implantation defects of human embryos.”
In addition to helping reduce the use of animals in research, synthetic embryo models might in the future become a reliable source of cells, tissues, and organs for transplantation. “Instead of developing a different protocol for growing each cell type – for example, those of the kidney or liver – we may one day be able to create a synthetic embryo-like model and then isolate the cells we need. We won’t need to dictate to the emerging organs how they must develop. The embryo itself does this best.”
A diagram showing the innovative method for growing synthetic mouse embryo models from stem cells – without egg, sperm or womb – developed in the laboratory of Prof. Jacob Hanna. Credit: Weizmann Institute of Science
Reference: “Post-Gastrulation Synthetic Embryos Generated Ex Utero from Mouse Naïve ESCs” by Shadi Tarazi, Alejandro Aguilera-Castrejon, Carine Joubran, Nadir Ghanem, Shahd Ashouokhi, Francesco Roncato, Emilie Wildschutz, Montaser Haddad, Bernardo Oldak, Elidet Gomez-Cesar, Nir Livnat, Sergey Viukov, Dmitry Lukshtanov, Segev Naveh-Tassa, Max Rose, Suhair Hanna, Calanit Raanan, Ori Brenner, Merav Kedmi, Hadas Keren-Shaul, Tsvee Lapidot, Itay Maza, Noa Novershtern and Jacob H. Hanna, 1 August 2022, Cell. DOI: 10.1016/j.cell.2022.07.028
This research was co-led by Shadi Tarazi, Alejandro Aguilera-Castrejon, and Carine Joubran of Weizmann’s Molecular Genetics Department. Study participants also included Shahd Ashouokhi, Dr. Francesco Roncato, Emilie Wildschutz, Dr. Bernardo Oldak, Elidet Gomez-Cesar, Nir Livnat, Sergey Viukov, Dmitry Lokshtanov, Segev Naveh-Tassa, Max Rose and Dr. Noa Novershtern of Weizmann’s Molecular Genetics Department; Montaser Haddad and Prof. Tsvee Lapidot of Weizmann’s Immunology and Regenerative Biology Department; Dr. Merav Kedmi of Weizmann’s Life Sciences Core Facilities Department; Dr. Hadas Keren-Shaul of the Nancy and Stephen Grand Israel National Center for Personalized Medicine; and Dr. Nadir Ghanem, Dr. Suhair Hanna and Dr. Itay Maza of the Rambam Health Care Campus.
Prof. Jacob Hanna’s research is supported by the Dr. Barry Sherman Institute for Medicinal Chemistry; the Helen and Martin Kimmel Institute for Stem Cell Research; and Pascal and Ilana Mantoux.
Long predicted but never observed, fluid-like electron whirlpools could be leveraged for next-gen low-power electronics. Credit: Christine Daniloff, MIT
Long predicted but never observed before, this fluid-like electron behavior could be leveraged for efficient low-power next-generation electronics.
Water molecules, although being distinct particles, flow collectively as liquids, creating streams, waves, whirlpools, and other classic fluid phenomena.
It isn’t the same with electricity. While an electric current is likewise constructed of distinct particles — in this case, electrons — the particles are so small that any collective behavior among them is drowned out by larger influences as electrons pass through ordinary metals. However, in particular materials and under specific conditions, such effects fade away, and electrons can directly influence each other. In these specific instances, electrons can flow collectively like a fluid.
Now, physicists at
Reported on July 6, 2022, in the journal Nature, the observations could inform the design of more efficient electronics.
“We know when electrons go in a fluid state, [energy] dissipation drops, and that’s of interest in trying to design low-power electronics,” Levitov says. “This new observation is another step in that direction.”
Levitov is a co-author of the new paper, along with Eli Zeldov and others at the Weizmann Institute for Science in Israel and the University of Colorado at Denver.
In most materials like gold (left), electrons flow with the electric field. But MIT physicists have found that in exotic tungsten ditelluride (right), the particles can reverse direction and swirl like a liquid. Credit: Courtesy of the researchers
A collective squeeze
When electricity runs through most ordinary metals and semiconductors, the momenta and trajectories of electrons in the current are influenced by impurities in the material and vibrations among the material’s atoms. These processes dominate electron behavior in ordinary materials.
But theorists have predicted that in the absence of such ordinary, classical processes, quantum effects should take over. Namely, electrons should pick up on each other’s delicate quantum behavior and move collectively, as a viscous, honey-like electron fluid. This liquid-like behavior should emerge in ultraclean materials and at near-zero temperatures.
In 2017, Levitov and colleagues at the University of Manchester reported signatures of such fluid-like electron behavior in graphene, an
Channeling flow
To visualize electron vortices, the team looked to tungsten ditelluride (WTe2), an ultraclean metallic compound that has been found to exhibit exotic electronic properties when isolated in single-atom-thin, two-dimensional form.
“Tungsten ditelluride is one of the new quantum materials where electrons are strongly interacting and behave as quantum waves rather than particles,” Levitov says. “In addition, the material is very clean, which makes the fluid-like behavior directly accessible.”
The researchers synthesized pure single crystals of tungsten ditelluride, and exfoliated thin flakes of the material. They then used e-beam lithography and
The researchers observed that electrons flowing through patterned channels in gold flakes did so without reversing direction, even when some of the current passed through each side chamber before joining back up with the main current. In contrast, electrons flowing through tungsten ditelluride flowed through the channel and swirled into each side chamber, much as water would do when emptying into a bowl. The electrons created small whirlpools in each chamber before flowing back out into the main channel.
“We observed a change in the flow direction in the chambers, where the flow direction reversed the direction as compared to that in the central strip,” Levitov says. “That is a very striking thing, and it is the same physics as that in ordinary fluids, but happening with electrons on the nanoscale. That’s a clear signature of electrons being in a fluid-like regime.”
The group’s observations are the first direct visualization of swirling vortices in an electric current. The findings represent an experimental confirmation of a fundamental property in electron behavior. They may also offer clues to how engineers might design low-power devices that conduct electricity in a more fluid, less resistive manner.
“Signatures of viscous electron flow have been reported in a number of experiments on different materials,” says Klaus Ensslin, professor of physics at ETH Zurich in Switzerland, who was not involved in the study. “The theoretical expectation of vortex-like current flow has now been confirmed experimentally, which adds an important milestone in the investigation of this novel transport regime.”
Reference: “Direct observation of vortices in an electron fluid” by A. Aharon-Steinberg, T. Völkl, A. Kaplan, A. K. Pariari, I. Roy, T. Holder, Y. Wolf, A. Y. Meltzer, Y. Myasoedov, M. E. Huber, B. Yan, G. Falkovich, L. S. Levitov, M. Hücker and E. Zeldov, 6 July 2022, Nature. DOI: 10.1038/s41586-022-04794-y
This research was supported, in part, by the European Research Council, the German-Israeli Foundation for Scientific Research and Development, and by the Israel Science Foundation.
Summary: Study uncovers the neural changes that occur during learning to improve discrimination of closely related visual objects.
Source: Max Planck Institute
Our visual perception of the world is often thought of as relatively stable. However, like all of our cognitive functions, visual processing is shaped by our experiences.
During both development and adulthood, learning can alter visual perception. For example, improved visual discrimination of similar patterns is a learned skill critical for reading.
In a new research study published in Current Biology, scientists have now discovered the neuronal changes that occur during learning to improve discrimination of closely related visual images.
This study, led by first author Dr. Joseph Schumacher and senior author Dr. David Fitzpatrick at the Max Planck Florida Institute for Neuroscience, establishes a transformative approach to studying perceptual learning in the brain.
Researchers imaged the activity of large numbers of single neurons over days to track the changes that occur while a visual discrimination task is learned, performing these experiments in a novel animal model, the tree shrew.
The tree shrew is a small mammal with visual properties akin to the human, including a high degree of visual acuity and a similar orderly spatial arrangement of visually responsive neurons in the brain. As the researchers show, these animals can also learn complex behavioral tasks, making them ideal for understanding how experience shapes visual perception.
In this study, tree shrews were trained to discriminate between highly similar visual images: identical black lines that differed only by a small change in orientation (22.5 degrees). In the task, the presentation of the lines at one orientation was rewarded with a drop of juice.
Over days, tree shrews learned to discriminate between the two similar visual images, licking only in response to the lines at the rewarded orientation and withholding licking to the lines at the non-rewarded orientation.
The scientists combined this behavioral task with measurements of neural activity in V1, an area of the brain essential for visual processing. The neurons in this area are activated by specific features of visual input, such as the orientation of light-dark edges.
Individual neurons show ‘preference’ for specific edge orientations, responding with the highest activity to these orientations and with progressively lower activity or no activity to edges orientated further from the preferred orientation.
In this way, a visual scene that has edges with different orientations activates particular subsets of neurons to generate a neural activity pattern that encodes the information needed for visual perception.
Schumacher and colleagues found that visual discrimination learning in the tree shrew was accompanied by enhancement of the difference in the patterns of neural activity evoked by the two visual images.
This was primarily due to an increase in the amount of neural activity in response to the presentation of the rewarded stimulus orientation relative to the non-rewarded orientation. But this was not just a general increase in neuronal responses to the rewarded stimulus.
When the scientists examined the changes more closely, they found that this was mediated by changes in the activity of a remarkably specific subset of neurons: those whose orientation preference was optimal for distinguishing the orientation of the rewarded stimulus from the non-rewarded stimulus.
To fully understand the effect of learning on visual perception, the authors next investigated whether the changes in neuronal activity that improved visual discrimination persisted outside of the learned task context.
The tree shrew is a small mammal with visual properties akin to the human, including a high degree of visual acuity and a similar orderly spatial arrangement of visually responsive neurons in the brain. Image is in the public domain
Interestingly, they found that the neuronal changes not only persisted but were accompanied by changes in the trained tree shrew’s abilities to perform other discriminations. This included both enhancements for some stimulus orientations and impairments for others—behavioral changes that were exactly what would be expected given the changes in the responses of this specific subset of neurons.
“This work demonstrates specific experience-driven changes in the activity of neurons that impact the perception of visual stimuli, enhancing discriminations relevant to task performance at the expense of other related discriminations,” explains first author Joe Schumacher.
Now the lab has set its sights on combining this approach with new technologies to unlock the sequence and changes that occur in multiple types of neurons in order to mediate perceptual learning.
See also
By probing these questions in the visual system of the tree shrew, scientists in the Fitzpatrick lab are discovering fundamental new insights about perceptual learning that could impact our understanding of a broad range of learning disorders.
About this visual learning research news
Author: Press Office Source: Max Planck Institute Contact: Press Office – Max Planck Institute Image: The image is in the public domain
Original Research: Closed access. “Selective enhancement of neural coding in V1 underlies fine-discrimination learning in tree shrew” by Joseph W. Schumacher et al. Current Biology
Abstract
Selective enhancement of neural coding in V1 underlies fine-discrimination learning in tree shrew
Highlights
Tree shrews learn to make fine visual discriminations of stimulus orientation
Learning is accompanied by enhanced discrimination capacity in V1 neurons
Enhancement is linked to changes in tuning properties of task-relevant neurons
Persistence of these changes leads to predictable biases in behavioral performance
Summary
Visual discrimination improves with training, a phenomenon that is thought to reflect plastic changes in the responses of neurons in primary visual cortex (V1). However, the identity of the neurons that undergo change, the nature of the changes, and the consequences of these changes for other visual behaviors remain unclear.
We used chronic in vivo 2-photon calcium imaging to monitor the responses of neurons in the V1 of tree shrews learning a Go/No-Go fine orientation discrimination task.
We observed increases in neural population measures of discriminability for task-relevant stimuli that correlate with performance and depend on a select subset of neurons with preferred orientations that include the rewarded stimulus and nearby orientations biased away from the non-rewarded stimulus. Learning is accompanied by selective enhancement in the response of these neurons to the rewarded stimulus that further increases their ability to discriminate the task stimuli.
These changes persist outside of the trained task and predict observed enhancement and impairment in performance of other discriminations, providing evidence for selective and persistent learning-induced plasticity in the V1, with significant consequences for perception.
Here we are again with another article about Stage Manager. One of the main features of iPadOS 16 has been making many iPad users upset as it requires the M1 chip, leaving users of older iPad models stuck with the original iPadOS multitasking system without floating windows. But it seems that Apple has its own ways of enabling Stage Manager on older iPads.
After all the controversy regarding Stage Manager, 9to5Mac decided to investigate by looking at the iPadOS 16 code. What we have found is that, in fact, Apple has an internal mode to enable Stage Manager on older iPads.
The codes reference an internal setting that enables “Chamois” (the Stage Manager codename) for “Legacy Devices.” In other words, it makes the feature work with every other non-M1 iPad running iPadOS 16. This aligns with a statement from Apple’s head of software engineering Craig Federighi, who said that Apple ran tests with Stage Manager on more iPad models before deciding that the feature requires the M1 chip.
We began some of our prototyping involving those systems and it became apparent early on that we couldn’t deliver the experience that that we were designing toward with them. Certainly, we would love to bring any new experience to every device we can, but we also don’t want to hold back the definition of a new experience and not create the best foundation for the future in that experience. And we really could only do that by building on the M1.
Of course, that doesn’t mean that Stage Manager works smoothly on older iPads, but having this option hidden in the first developer beta of iPadOS 16 suggests that the company’s engineers may still be running tests with the feature on some other iPad models.
The Stage Manager controversy
Having exclusive features for new hardware is not something new. However, when it comes to Stage Manager, users seem skeptical about the limitations pointed out by Apple.
For instance, Craig Federighi said in an interview that having virtual memory swap (something that is only available on the M1 chip) was crucial to creating Stage Manager since the feature supports up to eight apps open at the same time. However, it was later discovered that the 64GB iPad Air 5, which supports Stage Manager, lacks memory swap.
Apple executives also pointed out that the Stage Manager requirements had to be super high since the feature has smooth animations and beautiful shadows, but this also seems controversial since the feature is available for Intel Macs as old as 2017 with macOS Ventura.
It’s unclear at this point whether Apple will reconsider the requirements for Stage Manager in iPadOS 16. Last year when macOS Monterey was announced, Live Text was an exclusive feature for M1 Macs. However, after several complaints, Apple has made the feature available for Intel Macs as well.
I just wonder if we will ever get to see for ourselves how Stage Manager works on non-M1 iPads to draw our own conclusions thanks to some jailbreak tool.
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Created in the lab of Chemist Xavier Roy, CrSBr is a so-called van der Waals crystal that can be peeled into stackable, 2D layers that are just a few atoms thin. Unlike related materials that are quickly destroyed by oxygen and water, CrSBr crystals are stable at ambient conditions. These crystals also maintain their magnetic properties at the relatively high temperature of -280F, avoiding the need for expensive liquid helium cooled to a temperature of -450F.
Chromium sulfide bromide crystallizes into thin layers that can be peeled apart and stacked to create nanoscale devices. Columbia researchers discovered that this material’s electronic and magnetic properties are linked together—a discovery that could enable fundamental research as well as potential applications in spintronics. Credit: Myung-Geun Han and Yimei Zhu
“CrSBr is infinitely easier to work with than other 2D magnets, which lets us fabricate novel devices and test their properties,” said Evan Telford, a postdoc in the Roy lab who graduated with a PhD in physics from Columbia in 2020. Last year, colleagues Nathan Wilson and Xiaodong Xu at the
The team used an electric field to study CrSBr layers across different electron densities, magnetic fields, and temperatures—different parameters that can be adjusted to produce different effects in a material. As electronic properties in CrSBr changed, so did its magnetism.
“Semiconductors have tunable electronic properties. Magnets have tunable spin configurations. In CrSBr, these two knobs are combined,” said Roy. “That makes CrSBr attractive for both fundamental research and for potential spintronics application.”
“Semiconductors have tunable electronic properties. Magnets have tunable spin configurations. In CrSBr, these two knobs are combined.”
— Xavier Roy
Magnetism is a difficult property to measure directly, particularly as the size of the material shrinks, explained Telford, but it’s easy to measure how electrons move with a parameter called resistance. In CrSBr, resistance can serve as a proxy for otherwise unobservable magnetic states. “That’s very powerful,” said Roy, especially as researchers look to one day build chips out of such 2D magnets, which could be used for quantum computing and to store massive amounts of data in a small space.
The link between the material’s electronic and magnetic properties was due to defects in the layers—for the team, a lucky break, said Telford. “People usually want the ‘cleanest’ material possible. Our crystals had defects, but without those, we wouldn’t have observed this coupling,” he said.
From here, the Roy lab is experimenting with ways to grow peelable van der Waals crystals with deliberate defects, to improve the ability to fine-tune the material’s properties. They are also exploring whether different combinations of elements could function at higher temperatures while still retaining those valuable combined properties.
Reference: “Coupling between magnetic order and charge transport in a two-dimensional magnetic semiconductor” by Evan J. Telford, Avalon H. Dismukes, Raymond L. Dudley, Ren A. Wiscons, Kihong Lee, Daniel G. Chica, Michael E. Ziebel, Myung-Geun Han, Jessica Yu, Sara Shabani, Allen Scheie, Kenji Watanabe, Takashi Taniguchi, Di Xiao, Yimei Zhu, Abhay N. Pasupathy, Colin Nuckolls, Xiaoyang Zhu, Cory R. Dean and Xavier Roy, 5 May 2022, Nature Materials. DOI: 10.1038/s41563-022-01245-x
