Computers Math

Scientists have created the first “time-crystal” two-body system in an experiment that seems to bend the laws of physics.
It comes after the same team recently witnessed the first interaction of the new phase of matter.
Time crystals were long believed to be impossible because they are made from atoms in never-ending motion. The discovery, published in Nature Communications, shows that not only can time crystals be created, but they have potential to be turned into useful devices.
Time crystals are different from a standard crystal — like metals or rocks — which is composed of atoms arranged in a regularly repeating pattern in space.
First theorised in 2012 by Nobel Laureate Frank Wilczek and identified in 2016, time crystals exhibit the bizarre property of being in constant, repeating motion in time despite no external input. Their atoms are constantly oscillating, spinning, or moving first in one direction, and then the other.
EPSRC Fellow Dr Samuli Autti, lead author from Lancaster University’s Department of Physics, explained: “Everybody knows that perpetual motion machines are impossible. However, in quantum physics perpetual motion is okay as long as we keep our eyes closed. By sneaking through this crack we can make time crystals.”
“It turns out putting two of them together works beautifully, even if time crystals should not exist in the first place. And we already know they also exist at room temperature.”
A “two-level system” is a basic building block of a quantum computer. Time crystals could be used to build quantum devices that work at room temperature.
An international team of researchers from Lancaster University, Royal Holloway London, Landau Institute, and Aalto University in Helsinki observed time crystals by using Helium-3 which is a rare isotope of helium with one missing neutron. The experiment was carried out in Aalto University.
They cooled superfluid helium-3 to about one ten thousandth of a degree from absolute zero (0.0001K or -273.15°C). The researchers created two time crystals inside the superfluid, and brought them to touch. The scientists then watched the two time crystals interacting as described by quantum physics.
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Researchers have analysed the properties of an organic polymer with potential applications in flexible electronics and uncovered variations in hardness at the nanoscale, the first time such a fine structure has been observed in this type of material.
The field of organic electronics has benefited from the discovery of new semiconducting polymers with molecular backbones that are resilient to twists and bends, meaning they can transport charge even if they are flexed into different shapes.
It had been assumed that these materials resemble a plate of spaghetti at the molecular scale, without any long-range order. However, an international team of researchers found that for at least one such material, there are tiny pockets of order within. These ordered pockets, just a few ten-billionths of a metre across, are stiffer than the rest of the material, giving it a ‘fruitcake’ structure with harder and softer regions.
The work was led by the University of Cambridge and Park Systems UK Limited, with KTH Stockholm in Sweden, the Universities of Namur and Mons in Belgium, and Wake Forest University in the USA. Their results, reported in the journal Nature Communications, could be used in the development of next-generation microelectronic and bioelectronic devices.
Studying and understanding the mechanical properties of these materials at the nanoscale — a field known as nanomechanics — could help scientists fine-tune those properties and make the materials suitable for a wider range of applications.
“We know that the fabric of nature on the nanoscale isn’t uniform, but finding uniformity and order where we didn’t expect to see it was a surprise,” said Dr Deepak Venkateshvaran from Cambridge’s Cavendish Laboratory, who led the research.
The researchers used an imaging technique called higher eigen mode imaging to take nanoscale pictures of the regions of order within a semiconducting polymer called indacenodithiophene-co-benzothiadiazole (C16-IDTBT). These pictures showed clearly how individual polymer chains line up next to each other in some regions of the polymer film. These regions of order are between 10 and 20 nanometres across.
“The sensitivity of these detection methods allowed us to map out the self-organisation of polymers down to the individual molecular strands,” said co-author Dr Leszek Spalek, also from the Cavendish Laboratory. “Higher eigen mode imaging is a valuable method for characterising nanomechanical properties of materials, given the relatively easy sample preparation that is required.”
Further measurements of the stiffness of the material on the nanoscale showed that the areas where the polymers self-organised into ordered regions were harder, while the disordered regions of the material were softer. The experiments were performed in ambient conditions as opposed to an ultra-high vacuum, which had been a requirement in earlier studies.
“Organic polymers are normally studied for their applications in large area, centimetre scale, flexible electronics,” said Venkateshvaran. “Nanomechanics can augment these studies by developing an understanding of their mechanical properties at ultra-small scales with unprecedented resolutions.
“Together, the fundamental knowledge gained from both types of studies could inspire a new generation of soft microelectronic and bioelectronic devices. These futuristic devices will combine the benefits of centimetre scale flexibility, micrometre scale homogeneity, and nanometre scale electrically controlled mechanical motion of polymer chains with superior biocompatibility.”
The research was funded in part by the Royal Society.
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When the stakes are high, machine-learning models are sometimes used to aid human decision-makers. For instance, a model could predict which law school applicants are most likely to pass the bar exam to help an admissions officer determine which students should be accepted.
These models often have millions of parameters, so how they make predictions is nearly impossible for researchers to fully understand, let alone an admissions officer with no machine-learning experience. Researchers sometimes employ explanation methods that mimic a larger model by creating simple approximations of its predictions. These approximations, which are far easier to understand, help users determine whether to trust the model’s predictions.
But are these explanation methods fair? If an explanation method provides better approximations for men than for women, or for white people than for Black people, it may encourage users to trust the model’s predictions for some people but not for others.
MIT researchers took a hard look at the fairness of some widely used explanation methods. They found that the approximation quality of these explanations can vary dramatically between subgroups and that the quality is often significantly lower for minoritized subgroups.
In practice, this means that if the approximation quality is lower for female applicants, there is a mismatch between the explanations and the model’s predictions that could lead the admissions officer to wrongly reject more women than men.
Once the MIT researchers saw how pervasive these fairness gaps are, they tried several techniques to level the playing field. They were able to shrink some gaps, but couldn’t eradicate them. More

Interactive visualizations have changed the way we understand our lives. For example, they can showcase the number of coronavirus infections in each state.
But these graphics often are not accessible to people who use screen readers, software programs that scan the contents of a computer screen and make the contents available via a synthesized voice or Braille. Millions of Americans use screen readers for a variety of reasons, including complete or partial blindness, learning disabilities or motion sensitivity.
University of Washington researchers worked with screen-reader users to design VoxLens, a JavaScript plugin that — with one additional line of code — allows people to interact with visualizations. VoxLens users can gain a high-level summary of the information described in a graph, listen to a graph translated into sound or use voice-activated commands to ask specific questions about the data, such as the mean or the minimum value.
The team presented this project May 3 at CHI 2022 in New Orleans.
“If I’m looking at a graph, I can pull out whatever information I am interested in, maybe it’s the overall trend or maybe it’s the maximum,” said lead author Ather Sharif, a UW doctoral student in the Paul G. Allen School of Computer Science & Engineering. “Right now, screen-reader users either get very little or no information about online visualizations, which, in light of the COVID-19 pandemic, can sometimes be a matter of life and death. The goal of our project is to give screen-reader users a platform where they can extract as much or as little information as they want.”
Screen readers can inform users about the text on a screen because it’s what researchers call “one-dimensional information.”
“There is a start and an end of a sentence and everything else comes in between,” said co-senior author Jacob O. Wobbrock, UW professor in the Information School. “But as soon as you move things into two dimensional spaces, such as visualizations, there’s no clear start and finish. It’s just not structured in the same way, which means there’s no obvious entry point or sequencing for screen readers.” More

Your virtual visit with your doctor is at 1:00 p.m. It’s now 1:20 p.m. and your physician has not yet logged in. Do you call the clinic? Hang up and log back in? Groan in frustration?
Being stuck in a virtual waiting room and staring at a blank computer or device screen is a huge dissatisfier among telemedicine patients. To respect patients’ time, and provide the optimal experience, UC San Diego Health conducted a 10-week quality improvement study to evaluate how text messaging a link to a patient when their doctor is ready provides a way to connect patients and doctors most efficiently, without relying on the virtual waiting room.
Results of the study published in the May 27 online issue of Quality Management in Health Care.
“Borrowing from the airline and restaurant industries, we tested whether we could contact patients via text to log into their appointment when their doctor is ready. The goal of the feasibility study was to determine if this flexibility lead to improved perception of waiting time and an enhanced experience, while assessing for time saving for both patients and providers,” said Brett C. Meyer, MD, neurologist, co-director of the UC San Diego Heath Stroke Center, and clinical director of telehealth at UC San Diego Health.
“We stepped back and asked, ‘Do we need a virtual waiting room at all? Can we let patients know when their provider is available instead of making them wait online?'” said Emily S. Perrinez, RN, MSN, MPH, study co-author and director of telehealth operations at UC San Diego Health. “The reality is that wait times and lack of timely communication both correlate with patient experience. Real-time text notification that the provider is ready improved patient satisfaction and this experience is the kind of feedback we love to see.”
Twenty-two patients at a stroke clinic participated in the two-and-a-half month study. Patients chose to either receive a text, which included a visit link when their provider was ready for their visit or the standard telehealth routine of logging in at a scheduled time and waiting in front of a camera in a virtual waiting room. More

New research from the Department of Sociology in Trinity College Dublin has found further evidence of a relationship between online engagement and mental wellbeing in teenagers. The study, published recently in the journal ‘Computers in Human Behaviour’, contributes to mounting international evidence on the dangers of high levels of digital media use.
Additionally, the researchers found that in today’s connected world low engagement with digital media is also associated with poor mental health outcomes for adolescents who spend less time online than their peers. This finding supports the ‘goldilocks’ hypothesis — that digital media use at moderate levels is not intrinsically harmful and there is a point between low and high use that is ‘just right’ for young people.
This is the first time the ‘goldilocks’ theory has been examined in Irish teenagers/young adults. It is also the first study to attempt the integration of both time and online behaviours when examining associations between digital media and mental wellbeing.
Professor Richard Layte, Professor of Sociology and co-author on the paper, said:
“Evidence is mounting internationally that online engagement among adolescents may be damaging for mental well-being but the evidence is mixed. Our work provides fresh insights on the impact of digital engagement at the age of 17/18 and the results provide worrying evidence of real harms that require urgent action.”
“There is a simple narrative out there that more is worse. It is important to emphasise that online engagement is now a normal channel of social participation and non-use has consequences. Our findings also raise the possibility that moderate use is important in today’s digital world and that low levels of online engagement carries its own risks. Now the questions for researchers are how much is too much and how little is too little?”
The research, drawing on longitudinal data from the Growing Up in Ireland study, looked at the association between adolescent use of online engagement and mental wellbeing in over 6,000 young people between the age of 13 and again at the age of 17/18. More

A team led by University of Minnesota Twin Cities researchers has discovered how subtle structural changes in strontium titanate, a metal oxide semiconductor, can alter the material’s electrical resistance and affect its superconducting properties.
The research can help guide future experiments and materials design related to superconductivity and the creation of more efficient semiconductors for various electronic device applications.
The study is published in Science Advances, a peer-reviewed, multidisciplinary scientific journal published by the American Association for the Advancement of Science.
Strontium titanate has been on scientists’ radar for the past 60 years because it displays many interesting properties. For one, it becomes a superconductor, i.e. conducts electricity smoothly without resistance, at low temperatures and low concentrations of electrons. It also undergoes a structure change at 110 Kelvin (-262 degrees Fahrenheit), meaning the atoms in its crystalline structure change their arrangement. However, scientists are still debating what exactly causes superconductivity in this material on the microscopic level or what happens when its structure changes.
In this study, the University of Minnesota-led team was able to shine some light on these issues.
Using a combination of materials synthesis, analysis, and theoretical modeling, the researchers found that the structural change within strontium titanate directly affects how electric current flows through the material. They also revealed how small changes in the concentrations of electrons in the material affect its superconductivity. These insights will ultimately inform future research on this material, including research on its unique superconducting properties. More

One of the most tedious, daunting tasks for undergraduate assistants in university research labs involves looking hours on end through a microscope at samples of material, trying to find monolayers.
These two-dimensional materials — less than 1/100,000th the width of a human hair — are highly sought for use in electronics, photonics, and optoelectronic devices because of their unique properties.
“Research labs hire armies of undergraduates to do nothing but look for monolayers,” says Jaime Cardenas, an assistant professor of optics at the University of Rochester. “It’s very tedious, and if you get tired, you might miss some of the monolayers or you might start making misidentifications.”
Even after all that work, the labs then must doublecheck the materials with expensive Raman spectroscopy or atomic force microscopy.
Jesús Sánchez Juárez, a PhD student in the Cardenas Lab, has made life a whole lot easier for those undergraduates, their research labs, and companies that encounter similar difficulties in detecting monolayers.
The breakthrough technology, an automated scanning device described in Optical Materials Express, can detect monolayers with 99.9 percent accuracy — surpassing any other method to date. More