Computers Math

If you have young children, you’re likely worried about how much time they spend staring at a screen, be it a tablet, phone, computer, or television. You probably also want to know how screen time affects your child’s development and wonder whether there’s anything you can do to balance out any negative effects. New research from Japan indicates that more screen time at age 2 is associated with poorer communication and daily living skills at age 4 — but when kids also play outdoors, some of the negative effects of screen time are reduced.
In the study, which will be published in March in JAMA Pediatrics, the researchers followed 885 children from 18 months to 4 years of age. They looked at the relationship between three key features: average amount of screen time per day at age 2, amount of outdoor play at age 2 years 8 months, and neurodevelopmental outcomes — specifically, communication, daily living skills, and socialization scores according to a standardized assessment tool called Vineland Adaptive Behavior Scale-II — at age 4.
“Although both communication and daily living skills were worse in 4-year-old children who had had more screen time at aged 2, outdoor play time had very different effects on these two neurodevelopmental outcomes,” explains Kenji J. Tsuchiya, Professor at Osaka University and lead author of the study. “We were surprised to find that outdoor play didn’t really alter the negative effects of screen time on communication — but it did have an effect on daily living skills.”
Specifically, almost one-fifth of the effects of screen time on daily living skills were mediated by outdoor play, meaning that increasing outdoor play time could reduce the negative effects of screen time on daily living skills by almost 20%. The researchers also found that, although it was not linked to screen time, socialization was better in 4-year-olds who had spent more time playing outside at 2 years 8 months of age.
“Taken together, our findings indicate that optimizing screen time in young children is really important for appropriate neurodevelopment,” says Tomoko Nishimura, senior author of the study. “We also found that screen time is not related to social outcomes, and that even if screen time is relatively high, encouraging more outdoor play time might help to keep kids healthy and developing appropriately.”
These results are particularly important given the recent COVID-19-related lockdowns around the world, which have generally led to more screen time and less outdoor time for children. Because the use of digital devices is difficult to avoid even in very young children, further research looking at how to balance the risks and benefits of screen time in young children is eagerly awaited. More

An Aston University researcher has created the first ever computer reconstruction of a virus, including its complete native genome.
Although other researchers have created similar reconstructions, this is the first to replicate the exact chemical and 3D structure of a ‘live’ virus.
The breakthrough could lead the way to research into an alternative to antibiotics, reducing the threat of anti-bacterial resistance.
The research Reconstruction and validation of entire virus model with complete genome from mixed resolution cryo-EM density by Dr Dmitry Nerukh, from the Department of Mathematics in the College of Engineering and Physical Sciences at Aston University is published in the journal Faraday Discussions.
The research was conducted using existing data of virus structures measured via cryo-Electron Microscopy (cryo-EM), and computational modelling which took almost three years despite using supercomputers in the UK and Japan.
The breakthrough will open the way for biologists to investigate biological processes which can’t currently be fully examined because the genome is missing in the virus model.

This includes finding out how a bacteriophage, which is a type of virus that infects bacteria, kills a specific disease-causing bacterium.
At the moment it is not known how this happens, but this new method of creating more accurate models will open up further research into using bacteriophage to kill specific life-threatening bacteria.
This could lead to more targeted treatment of illnesses which are currently treated by antibiotics, and therefore help to tackle the increasing threat to humans of antibiotic resistance.
Dr Nerukh said: “Up till now no one else had been able to build a native genome model of an entire virus at such detailed (atomistic) level.
“The ability to study the genome within a virus more clearly is incredibly important. Without the genome it has been impossible to know exactly how a bacteriophage infects a bacterium.
“This development will now allow help virologists answer questions which previously they couldn’t answer.
“This could lead to targeted treatments to kill bacteria which are dangerous to humans, and to reduce the global problem of antibiotic-resistant bacteria which are over time becoming more and more serious.”
The team’s approach to the modelling has many other potential applications. One of these is creating computational reconstructions to assist cryo-Electron Microscopy — a technique used to examine life-forms cooled to an extreme temperature. More

Engineers at the University of Colorado Boulder are tapping into advances in artificial intelligence to develop a new kind of walking stick for people who are blind or visually impaired.
Think of it as assistive technology meets Silicon Valley.
The researchers say that their “smart” walking stick could one day help blind people navigate tasks in a world designed for sighted people — from shopping for a box of cereal at the grocery store to picking a private place to sit in a crowded cafeteria.
“I really enjoy grocery shopping and spend a significant amount of time in the store,” said Shivendra Agrawal, a doctoral student in the Department of Computer Science. “A lot of people can’t do that, however, and it can be really restrictive. We think this is a solvable problem.”
In a study published in October, Agrawal and his colleagues in the Collaborative Artificial Intelligence and Robotics Lab got one step closer to solving it.
The team’s walking stick resembles the white-and-red canes that you can buy at Walmart. But it also includes a few add-ons: Using a camera and computer vision technology, the walking stick maps and catalogs the world around it. It then guides users by using vibrations in the handle and with spoken directions, such as “reach a little bit to your right.”
The device isn’t supposed to be a substitute for designing places like grocery stores to be more accessible, Agrawal said. But he hopes his team’s prototype will show that, in some cases, AI can help millions of Americans become more independent.

“AI and computer vision are improving, and people are using them to build self-driving cars and similar inventions,” Agrawal said. “But these technologies also have the potential to improve quality of life for many people.”
Take a seat
Agrawal and his colleagues first explored that potential by tackling a familiar problem: Where do I sit?
“Imagine you’re in a café,” he said. “You don’t want to sit just anywhere. You usually take a seat close to the walls to preserve your privacy, and you usually don’t like to sit face-to-face with a stranger.”
Previous research has suggested that making these kinds of decisions is a priority for people who are blind or visually impaired. To see if their smart walking stick could help, the researchers set up a café of sorts in their lab — complete with several chairs, patrons and a few obstacles.

Study subjects strapped on a backpack with a laptop in it and picked up the smart walking stick. They swiveled to survey the room with a camera attached near the cane handle. Like a self-driving car, algorithms running inside the laptop identified the various features in the room then calculated the route to an ideal seat.
The team reported its findings this fall at the International Conference on Intelligent Robots and Systems in Kyoto, Japan. Researchers on the study included Bradley Hayes, assistant professor of computer science, and doctoral student Mary Etta West.
The study showed promising results: Subjects were able to find the right chair in 10 out of 12 trials with varying levels of difficulty. So far, the subjects have all been sighted people wearing blindfolds. But the researchers plan to evaluate and improve their device by working people who are blind or visually impaired once the technology is more dependable.
“Shivendra’s work is the perfect combination of technical innovation and impactful application, going beyond navigation to bring advancements in underexplored areas, such as assisting people with visual impairment with social convention adherence or finding and grasping objects,” Hayes said.
Let’s go shopping
Next up for the group: grocery shopping.
In new research, which the team hasn’t yet published, Agrawal and his colleagues adapted their device for a task that can be daunting for anyone: finding and grasping products in aisles filled with dozens of similar-looking and similar-feeling choices.
Again, the team set up a makeshift environment in their lab: this time, a grocery shelf stocked with several different kinds of cereal. The researchers created a database of product photos, such as boxes of Honey Nut Cheerios or Apple Jacks, into their software. Study subjects then used the walking stick to scan the shelf, searching for the product they wanted.
“It assigns a score to the objects present, selecting what is the most likely product,” Agrawal said. “Then the system issues commands like ‘move a little bit to your left.'”
He added that it will be a while before the team’s walking stick makes it into the hands of real shoppers. The group, for example, wants to make the system more compact, designing it so that it can run off a standard smartphone attached to a cane.
But the human-robot interaction researchers also hope that their preliminary results will inspire other engineers to rethink what robotics and AI are capable of.
“Our aim is to make this technology mature but also attract other researchers into this field of assistive robotics,” Agrawal said. “We think assistive robotics has the potential to change the world.” More

Gene therapies have the potential to treat neurological disorders like Alzheimer’s and Parkinson’s diseases, but they face a common barrier — the blood-brain barrier. Now, researchers at the University of Wisconsin-Madison have developed a way to move therapies across the brain’s protective membrane to deliver brain-wide therapy with a range of biological medications and treatments.
“There is no cure yet for many devastating brain disorders,” says Shaoqin “Sarah” Gong, UW-Madison professor of ophthalmology and visual sciences and biomedical engineering and researcher at the Wisconsin Institute for Discovery. “Innovative brain-targeted delivery strategies may change that by enabling noninvasive, safe and efficient delivery of CRISPR genome editors that could, in turn, lead to genome-editing therapies for these diseases.”
CRISPR is a molecular toolkit for editing genes (for example, to correct mutations that may cause disease), but the toolkit is only useful if it can get through security to the job site. The blood-brain barrier is a membrane that selectively controls access to the brain, screening out toxins and pathogens that may be present in the bloodstream. Unfortunately, the barrier bars some beneficial treatments, like certain vaccines and gene therapy packages, from reaching their targets because in lumps them in with hostile invaders.
Injecting treatments directly into the brain is one way to get around the blood-brain barrier, but it’s an invasive procedure that provides access only to nearby brain tissue.
“The promise of brain gene therapy and genome-editing therapy relies on the safe and efficient delivery of nucleic acids and genome editors to the whole brain,” Gong says.
In a study recently published in the journal Advanced Materials, Gong and her lab members, including postdoctoral researcher and first author of the study Yuyuan Wang, describe a new family of nano-scale capsules made of silica that can carry genome-editing tools into many organs around the body and then harmlessly dissolve.
By modifying the surfaces of the silica nanocapsules with glucose and an amino acid fragment derived from the rabies virus, the researchers found the nanocapsules could efficiently pass through the blood-brain barrier to achieve brain-wide gene editing in mice. In their study, the researchers demonstrated the capability of the silica nanocapsule’s CRISPR cargo to successfully edit genes in the brains of mice, such as one related to Alzheimer’s disease called amyloid precursor protein gene.
Because the nanocapsules can be administered repeatedly and intravenously, they can achieve higher therapeutic efficacy without risking more localized and invasive methods.
The researchers plan to further optimize the silica nanocapsules’ brain-targeting capabilities and evaluate their usefulness for the treatment of various brain disorders. This unique technology is also being investigated for the delivery of biologics to the eyes, liver and lungs, which can lead to new gene therapies for other types of disorders. More

Synthetic populations are computer-generated groups of people that are designed to look like real populations. They are built using public census information about people’s characteristics, such as their age, gender, and job, alongside statistical algorithms that help put it all together. Their main application is for conducting so-called social simulations to assess different possible solutions to social problems, such as transportation, health issues, and housing. During the COVID-19 pandemic, for example, scientists in many places around the world conducted social simulations to estimate the number of cases in each country.
In Japan, researchers have been carrying out such simulations using supercomputers under the COVID-19 AI & Simulation Project led by the Cabinet Secretariat of the Japanese government since 2020. They were given significant consideration when deciding various political measures, such as PCR testing policies, immigration limits, domestic tourism support, vaccination programs, and so on. These simulations were possible thanks to a synthetic population which was prepared and updated under the Joint Usage/Research Center for Interdisciplinary Large-scale Information Infrastructures (JHPCN) project, since 2017.
However, this Japanese synthetic population had a significant limitation — even though a home address was one of the attributes assigned to each individual, their workplace location was not. As a result, this synthetic population was more accurate at representing the night-time distribution of people, but not their day-time distribution, or the relationship between both.
To tackle this problem, a trio of Japanese researchers including Assistant Professor Takuya Harada of Shibaura Institute of Technology, as well as Dr. Tadahiko Murata and Mr. Daiki Iwase of the Faculty of Informatics at Kansai University, recently devised a method to assign a workplace attribute to each worker in synthetic populations. Their study was published in IEEE Transactions on Computational Social Systems and was supported by both JHPCN and the Japan Science and Technology Agency (JST).
The main challenge the researchers had to overcome was the lack of statistical information linking home and workplace locations for people. In Japan, only local governments whose area has over 200,000 residents release complete origin-destination-industry (ODI) statistics, which provide details about the movement of workers as well as their industry type (like retail, construction, or manufacturing). For cities, towns, or villages with less than 200,000 residents, the available ODI data is less specific, and only tells whether the person works in the same city, in another city within the same prefecture, or in another city in a different prefecture. Unfortunately, approximately 48% of workers in Japan reside in cities with less than 200,000 residents.
Thus, the research team combined available ODI data with origin-destination (OD) data and developed an innovative workplace assignment method that works for all cities, towns, and villages in Japan. To test whether their method was designed properly, they used it to assign workplaces to people in cities with more than 200,000 residents and compared the results with the available complete ODI data. For the city of Takatsuki in the Osaka prefecture, which the researchers showcased as an example in their paper, the proposed method could assign the correct cities as workplaces for 88.2% of workers.
The possible applications for detailed social simulations using synthetic populations are manyfold, as Professor Murata of Kansai University remarks: “Real-scale social simulations can be used for estimating the efficiency of urban developments, including housing and transportation projects, as well as the influence of social programs conducted by national or local governments. They can also be employed for rescue and relief programs when facing disasters such as earthquakes, tsunamis, floods, typhoons, and pandemics.” Put simply, social simulations can help decisionmakers accurately image various possible futures.
Another important aspect of synthetic populations is that they are free from data privacy concerns. “Synthetic populations are a secure technology because no private information is used,” explains Assistant Professor Harada, “Because we synthesize multiple sets of populations that have the same statistical characteristics, third parties cannot identify whether real information is included or not.” Worth noting, this study marks the world’s first synthetic populations with workplace information that are publicly released for engineers and researchers.
The research team is already working on using their newfound workplace assignment method to estimate the day-time population distribution throughout all of Japan. More

As buzz grows ever louder over the future of quantum, researchers everywhere are working overtime to discover how best to unlock the promise of super-positioned, entangled, tunneling or otherwise ready-for-primetime quantum particles, the ability of which to occur in two states at once could vastly expand power and efficiency in many applications.
Developmentally, however, quantum devices today are “about where the computer was in the 1950s,” which it is to say, the very beginning. That’s according to Kamyar Parto, a sixth-year Ph.D. student in the UC Santa Barbara lab of Galan Moody, an expert in quantum photonics and an assistant professor of electrical and computer engineering. Parto is co-lead author of a paper published in the journal Nano Letters, describing a key advance: the development of a kind of on-chip “factory” for producing a steady, fast stream of single photons, essential to enabling photonic-based quantum technologies.
In the early stages of computer development, Parto explained, “Researchers had just made the transistor, and they had ideas for how to make a digital switch, but the platform was kind of weak. Different groups developed different platforms, and eventually, everyone converged on CMOS (complementary metal-oxide semiconductor). Then, we had the huge explosion around semiconductors.
“Quantum technology is in a similar place — we have the idea and a sense of what we could do with it, and there are many competing platforms, but no clear winner yet,” he continued. “You have superconducting qubits, spin qubits in silicon, electrostatic spin qubits and ion-trap-based quantum computers. Microsoft is trying to do topologically protected qubits, and in the Moody Lab, we’re working on quantum photonics.”
Parto predicts that the winning platform will be a combination of different platforms, given that each is powerful but also has limitations. “For instance, it’s very easy to transfer information using quantum photonics, because light likes to move,” he said. “A spin qubit, however, makes it easier to store information and do some local ‘stuff’ on it, but you can’t move that data around. So, why don’t we try to use photonics to transfer the data from the platform that stores it better, and then transform it again to another format once it’s there?”
Qubits, those strangely behaving drivers of quantum technologies, are, of course, different from classical bits, which can exist in only a single state of zero or one. Qubits can be both one and zero simultaneously. In the realm of photonics, Parto said, a single photon can be made both to exist (state one) and not to exist (state zero).

That is because a single photon constitutes what is called a two-level system, meaning that it can exist in a zero state, a one state, or any combination, such as 50% one and 50% zero, or maybe 80% one and 20% zero. This can be done routinely in the Moody group. The challenge is to generate and collect single photons with very high efficiency, such as by routing them on a chip using waveguides. Waveguides do exactly what their name suggests, guiding the light where it needs to go, much as wires guide electricity.
Parto explained: “If we put these single photons into many different waveguides — a thousand single photons on each waveguide — and we sort of choreograph how the photons travel along the waveguides on the chip, we can do a quantum computation.”
While it is relatively simple to use waveguides to route photons on chip, isolating a single photon is not easy, and setting up a system that produces billions of them rapidly and efficiently is much harder. The new paper describes a technique that employs a peculiar phenomenon to generate single photons with an efficiency that is much greater than has been achieved previously.
“The work is about amplifying the generation of these single photons so that they become useful to actual applications,” Parto said. “The breakthrough described in this paper is that we can now generate the single photons reliably at room temperature in a way that lends itself to (the mass-production process of) CMOS.”
There are various ways to go about generating single photons, but Parto and his colleagues are doing it by using defects in certain two-dimensional (2D) semiconductor materials, which are only one atom thick, essentially removing a bit of the material to create a defect.

“If you shine light (generated by a laser) onto the right kind of defect, the material will respond by emitting single photons,” Parto said, adding, “The defect in the material acts as what is called a rate-limiting state, which allows it to behave like a factory for pushing out single photons, one at a time.” One photon might be produced as often as every three to five nanoseconds, but the researchers aren’t yet sure of the rate, and Parto, who earned his Ph.D. on the topic of engineering such defects, says that the current rate could be much slower.
A big advantage of 2D materials is that they lend themselves to having defects engineered into them at specific locations. Further, Parto said, “The materials are so thin that you can pick them up and put them on any other material without being constrained by the lattice geometry of a 3D crystal material. That makes the 2D material very easy to integrate, a capability we show in this paper.”
To make a useful device, the defect on the 2D material must be placed in the waveguides with extreme precision. “There is one point on the material that produces light from a defect,” Parto noted, “and we need to get that single photon into a waveguide.”
Researchers try to do that in a couple of ways, for instance, by putting the material on the waveguide and then looking for an existing single defect, but even if the defect is precisely aligned and in exactly the right position, the extraction efficiency will be only 20% to 30%. That is because the single defect can emit only at one specific rate, and some of the light is emitted at oblique angles, rather than directly along the path to the waveguide. The theoretical upper limit of that design is only 40%, but making a useful device for quantum-information applications requires 99.99% extraction efficiency.
“The light from a defect inherently shines everywhere, but we prefer that it shine into these waveguides,” Parto explained. “We have two choices. If you put waveguides on top of the defect, maybe ten to fifteen percent of the light would go into the waveguides. That’s not enough. But there is a physics phenomenon, called the Purcell effect, that we can utilize to boost this efficiency and direct more of the light into the waveguide. You do that by placing the defect inside an optical cavity — in our case it’s in the shape of a micro-ring resonator, which is one of the only cavities that allows you to couple light into and out of a waveguide.
“If the cavity is small enough,” he added, “it will squeeze out the vacuum fluctuations of the electromagnetic field, and those fluctuations are what cause the spontaneous emission of photons from the defect into a mode of light. By squeezing that quantum fluctuation into a cavity of finite volume, the fluctuation over the defect is increased, causing it to emit light preferentially into the ring, where it accelerates and becomes brighter, thus increasing the extraction efficiency.”
In experiments using the micro-ring resonator that were done for this paper, the team achieved extraction efficiency of 46%, which is an order-of-magnitude increase over prior reports.
“We’re really encouraged by these results, because single-photon emitters in 2D materials address some of the outstanding challenges facing other materials in terms of scalability and manufacturability,” said Moody. “In the near term, we’ll explore using them for a few different applications in quantum communications, but in the long term, our goal is to continue to develop this platform for quantum computing and networking.”
To do that, the group needs to improve their efficiency to better than 99%, and achieving that will require higher-quality nitride resonator rings. “To enhance efficiency, you need to smooth out the ring when you carve it out of the silicon nitride film,” Parto explained. “However, if the material itself is not fully crystalline, even if you try to smooth it at the atomic level, the surfaces could still look rough and sponge-like, causing the light to scatter off of them.”
While some groups achieve the highest-quality nitride by purchasing it from companies that grow it perfectly, Parto explained, “We have to grow it ourselves, because we have to put the defect under the material, and also, we’re using a special type of silicon nitride that minimizes the background light for single-photon applications, and the companies don’t do that.”
Parto can grow his nitrides in a plasma-enhanced chemical vapor deposition oven in the cleanroom at UCSB, but because it is a heavily used shared facility, he is not able to customize some settings that would allow him to grow material of sufficient quality. The, plan, he says, is to use these results to apply for new grants that would make it possible “to get our own tools and hire students to do this work.” More

A new type of polysulfate compound that can form thin, flexible films has properties that could make it a material of choice for many high-performance electrical components, according to a study from chemists and materials scientists at Scripps Research and the Lawrence Berkeley National Laboratory (LBNL).
In the study, published January 18 in Joule, the scientists found that the new polysulfates can be used to make polymer film capacitors that store and discharge high density of electrical energy while tolerating heat and electric fields beyond the limits of existing polymer film capacitors.
“Our findings suggest that energy-storing capacitors and other devices based on these new polysulfates could see wide application, including in electric vehicle power systems,” says study co-senior author Peng Wu, PhD, a professor in the Department of Molecular Medicine at Scripps Research.
The other co-senior authors were K. Barry Sharpless, PhD, W.M. Keck Professor of Chemistry at Scripps Research, and Yi Liu, PhD, Facility Director for Organic and Macromolecular Synthesis at LBNL’s Molecular Foundry, a multidisciplinary facility for the scientific and technical investigation of new materials.
The Sharpless and Wu labs recently synthesized many previously inaccessible polysulfates using the sulfur fluoride exchange (SuFEx) reaction, which was discovered in the Sharpless lab. SuFEx is part of a growing set of molecule-building methods known as click chemistry for their high efficiency and easy reaction requirements. Sharpless was awarded a share of the 2022 Nobel Prize in Chemistry for his pioneering work on click chemistry methods.
In investigations at Liu’s lab at LBNL’s Molecular Foundry, the researchers discovered that some of the new polysulfates have superior “dielectric” properties. Dielectric materials are electrical insulators in which positive and negative charges separate — storing energy, in effect — when the materials are exposed to electric fields. They are used in capacitors, transistors and other ubiquitous components of modern electronic circuits.

Many of the dielectric materials in contemporary use are lightweight, flexible, plastic-like materials called polymers. The new polysulfates also are polymers, but have greatly improved properties compared to commercial dielectric polymers. The team found that capacitors made from one of the new polysulfates, when enhanced with a thin film of aluminum oxide, could discharge a high density of energy, while withstanding electric fields (more than 700 million volts per meter) and temperatures (150 degrees C) that would destroy the most widely used polymer film capacitors.
The researchers noted that the heat sensitivity of standard polymer capacitors often necessitates expensive and cumbersome cooling measures in systems that use them — for example, in some electric car models. Thus, adoption of the new polysulfate dielectrics could lead to cheaper, simpler, more durable power systems in electric cars and many other applications, they say.
“I was very surprised at first, and still am — I think we all are. How can a classic force from the domain of physics, like the electric field force, be modulated by a thin chemical-polymer film in its path? The results speak for themselves though, and now seems a good time to share this puzzle,” says Sharpless.
The researchers continue to synthesize and investigate new polysulfates to find some that have even better properties.
“The polysulfate polymers we examined in this study can do very well at 150 degrees C, but we think we can find related polysulfates that can handle 200 to 250 degrees C with little or no loss of function,” Liu says.
“High performing polysulfate dielectrics for electrostatic energy storage under harsh conditions” was co-authored by He Li, Boyce Chang, Antoine Laine, Le Ma, Chongqing Yang, Junpyo Kwon, Steve Shelton, Liana Klivansky, Virginia Altoe, Adam Schwartzberg, Robert Ritchie, Ting Xu, Miquel Salmeron, Ricardo Ruiz, and Yi Liu, all of LBNL; Zongliang Xie, Tianlei Xu and Zongren Peng of Xi’an Jiaotong University; and by Hunseok Kim, Bing Gao, K. Barry Sharpless, and Peng Wu of Scripps Research.
The research was funded in part by the Department of Energy (DE-AC02-05CH11231,), the National Science Foundation (CHE-1610987), and the National Institutes of Health (R35GM1139643). More