Computers Math

Over the last year, handshakes have been replaced by fist or elbow bumps as a greeting. It shows that age-old social conventions can not only change, but do so suddenly. But how does this happen? Robotic engineers and marketing scientists from the University of Groningen joined forces to study this phenomenon, combining online experiments and statistical analysis into a mathematical model that shows how a committed minority can influence the majority to overturn long-standing practices. The results, which were published in Nature Communications on 29 September, may help to stimulate sustainable behaviour.
How does complex human behaviour take shape? This is studied in many ways, mostly relying on lots of data from observations and experiments. Ming Cao, Professor of Networks and Robotics at the Faculty of Science and Engineering at the University of Groningen, has studied complex group behaviour in robots by using agent-based simulations, among other methods. These agents follow a limited number of simple rules, often inspired by nature, which can lead to realistic complex behaviour. ‘Swarming birds or schools of fish are a good example’, Cao explains, ‘their movements can be reproduced by agents that follow a few simple rules on keeping a certain distance and heading in the same direction as their neighbours.’
Game
In parallel, the Marketing research group at the Faculty of Economics and Business, led by Dr Jan Willem Bolderdijk, Dr Hans Risselada, and Prof. Bob Fennis, has carried out various research projects into human behaviour, but not so many using these kinds of agent-based models. After a discussion with Cao and his colleagues, both groups saw possibilities for such models. Consequently, marketing PhD student Zan Mlakar and the two post-doc researchers in Cao’s group, Mengbin Ye and Lorenzo Zino, worked together creating an online experiment to gather data on the social diffusion of new behavioural trends.
They developed an online game in which 12 participants act as board members of a company that plans to launch one of two potential products. The participants have to vote on which product to launch. The catch is that the decision has to be taken unanimously. The participants cannot discuss their choice, they vote in 24 consecutive rounds, and they only see the distribution of votes at the end of each round. If unanimity is reached, the participants receive a reward.
Rules
Unknown to the participants, between two to four participants in the groups studied were computer bots, programmed to stick to their choice. ‘If the majority voted for product A in the first round, the bots were set to vote for B to try and overturn the majority’, explains Ye, who now works as Senior Research Fellow at Curtin University in Australia. Meanwhile, the votes of the human participants over all the rounds studied were registered. The vast majority of over 20 of these online game rounds resulted in a unanimous vote, with humans eventually siding with the bots to vote for product B. The results of all the games were then analysed to look for patterns in the voting decisions of the human participants.
Ye: ‘In quite few cases, we saw a delay before the votes started changing, but when they did, the group would reach unanimity in just a few voting rounds.’ The overall voting behaviour was able to be reproduced in an agent-based model with three simple rules: do as the majority does, stick to your previous decision, and follow the trend. ‘These rules are acknowledged in the literature as group coordination, inertia, and trend-seeking’, explains Ye. ‘They have been separately studied in human behaviour, but never combined in one model; this combination was critical in capturing social change.’
The results of the experiments and the simulations show that new conventions can suddenly arise when the influence of a committed minority reaches a threshold. A small group of ‘activists’ can therefore change social conventions. Cao: ‘However, this only happens if the minority is also able to influence others in their network. And this depends on the amount of risk-taking present among the other voters.’ The team are now interested in exploring what might enhance or inhibit this risk-taking behaviour. ‘We now have a solid framework and a model, which can be used to examine environmental factors that might make people have greater inertia, or be more susceptible to trends’, says Ye.
The three basic rules could help in steering the behaviour of large groups. ‘Of course, we can’t control people’, stresses Cao. ‘But we can provide guidelines, for example on how to nudge people to change their behaviour.’ This could be useful in the energy transition, or in getting people to reduce their meat consumption. ‘Governments already spend money to convince people to adopt more sustainable behaviour. Our research can help them to spend it in a more effective way.’
Story Source:
Materials provided by University of Groningen. Note: Content may be edited for style and length. More

Patients using take-home technology following non-elective surgery resulted in significantly greater detection and correction of drug errors, and reduction in patients’ pain, says a national study led by Hamilton researchers.
The study looked at patient outcomes from virtual care and remote automated monitoring (RAM) — video calls with nurses and doctors, and self-monitoring of vital signs using wearable devices.
The research also raised the possibility of a reduction in acute-hospital care as the result of virtual care and RAM.
“We began the study in the first months of the pandemic, when hospitals were challenged to drastically reduce non-emergency care,” said P.J. Devereaux, co-principal investigator of the study.
He is a senior scientist at the Population Health Research Institute (PHRI), professor and director of the division of perioperative care at McMaster University, and a cardiologist and perioperative care physician at Hamilton Health Sciences.
“Our study provides proof of concept that virtual care with RAM can improve outcomes after discharge following non-elective surgery — outcomes that are important to patients,” he said. More

A team led by the Department of Energy’s Oak Ridge National Laboratory has found a rare quantum material in which electrons move in coordinated ways, essentially “dancing.” Straining the material creates an electronic band structure that sets the stage for exotic, more tightly correlated behavior — akin to tangoing — among Dirac electrons, which are especially mobile electric charge carriers that may someday enable faster transistors. The results are published in the journal Science Advances.
“We combined correlation and topology in one system,” said co-principal investigator Jong Mok Ok, who conceived the study with principal investigator Ho Nyung Lee of ORNL. Topology probes properties that are preserved even when a geometric object undergoes deformation, such as when it is stretched or squeezed. “The research could prove indispensable for future information and computing technologies,” added Ok, a former ORNL postdoctoral fellow.
In conventional materials, electrons move predictably (for example, lethargically in insulators or energetically in metals). In quantum materials in which electrons strongly interact with each other, physical forces cause the electrons to behave in unexpected but correlated ways; one electron’s movement forces nearby electrons to respond.
To study this tight tango in topological quantum materials, Ok led the synthesis of an extremely stable crystalline thin film of a transition metal oxide. He and colleagues made the film using pulsed-laser epitaxy and strained it to compress the layers and stabilize a phase that does not exist in the bulk crystal. The scientists were the first to stabilize this phase.
Using theory-based simulations, co-principal investigator Narayan Mohanta, a former ORNL postdoctoral fellow, predicted the band structure of the strained material. “In the strained environment, the compound that we investigated, strontium niobate, a perovskite oxide, changes its structure, creating a special symmetry with a new electron band structure,” Mohanta said.
Different states of a quantum mechanical system are called “degenerate” if they have the same energy value upon measurement. Electrons are equally likely to fill each degenerate state. In this case, the special symmetry results in four states occurring in a single energy level. More

Transparent materials have become an essential component in a wide variety of technological applications, ranging from everyday electronics like tablets and smartphones to more sophisticated uses in solar panels, medicine, and optics. Just as for any other product to be mass-produced, quality control is important for these materials, and several techniques have been developed to detect microscopic scratches or imperfections.
One attractive approach to scanning for damages on materials is using “Lamb waves.” Named after the British mathematician Sir Horace Lamb, these are elastic waves generated in solid plates following an appropriate mechanical excitation. Because the propagation of Lamb waves is affected by surface damage (such as scratches), they can be leveraged to ensure that the scanned material is free from imperfections. Unfortunately, the generation and subsequent measurement of Lamb waves on transparent materials are not straightforward.
While laser-based techniques exist for generating Lamb waves in a contactless manner, the laser parameters need to be carefully calibrated for each material to avoid causing damage. Moreover, existing approaches do not generate Lamb waves of sufficient amplitude; as such, repeated measurements have to be conducted and averaged to get reliable data, which is time-consuming. As for measuring the generated Lamb waves, no existing technique can quickly detect and use them to look for submillimeter-scale damage on transparent surfaces.
To address these issues, a research team led by Professor Naoki Hosoya from Shibaura Institute of Technology and Takashi Onuma from Photron Limited, Japan, developed a novel framework for the generation and detection of “S0 mode” (zero-order symmetrical mode) Lamb waves in transparent materials. Their approach is presented in a paper recently published online in the journal Optics and Lasers in Engineering.
First, the team had to find a convenient technique to generate Lamb waves without damaging the sample. To this end, they leveraged an approach that they had used successfully in other endeavors to generate mechanical oscillations in a contactless way: laser-induced plasma (LIP) shock waves. To put it simply, LIP can be generated by focusing a beam of high-energy laser on a tiny volume of gas. The energy of the laser energizes the gas molecules and causes them to ionize, creating an unstable “plasma bubble” close to the material’s surface. “The plasma bubble expands to its surroundings at super high speeds, generating a shock wave that is used as the excitation force to produce Lamb waves on the target structure,” explains Prof. Hosoya.
Next, the researchers needed to measure the generated waves. They achieved this by using a high-speed polarization camera, which, as the name implies, can capture the polarization of the light traveling through the transparent sample. This polarization contains information directly related to the material’s mechanical stress distribution, which, in turn, reflects the propagation of Lamb waves.
To put their strategy to the test, the team created microscopic scratches on a few flat, transparent polycarbonate plates and compared the propagation of Lamb waves on damaged and pristine samples. As expected, the scratches caused noticeable differences in the stress distribution of the plates as the waves propagated over the damaged areas, demonstrating the potential of this novel approach by detecting scratches measuring only several dozen micrometers.
While the findings are exciting, further studies are warranted to gain a more in-depth understanding of their strategy and its limits. Prof. Hosoya says, “The effects of the damage size or type, the camera lens magnification, and the properties of the transparent sample on the detectable defect size limit of our method needs to be verified as part of future works.”
Hopefully, this ingenious non-contact, non-destructive damage detection scheme will help reduce the production costs of high-quality transparent materials.
Story Source:
Materials provided by Shibaura Institute of Technology. Note: Content may be edited for style and length. More

In a negotiation, how tough should your first offer be? New research shows the first offer can have a significant impact on the eventual outcome, and if you try to drive too hard a bargain, it could backfire.
Whether you’re buying a house, a car, or second-hand furniture, it’s likely you will need to negotiate the price, so being able to negotiate effectively could save you significant cash.
Behavioural economist Professor Lionel Page from the University of Technology Sydney (UTS) said opening offers in real-world negotiations are sometimes intended to signal the “toughness” of the buyer — but whether this strategy actually works was not known.
“This experiment allowed us to study whether and how the level of the opening offer influences the beliefs of buyers and sellers, their actions and the final bargaining outcome,” said Professor Page.
The researchers conducted the experiment using a bargaining game where players exchanged offers for a split of $10. The aim was to mimic the start of a typical negotiation process.
They found that the success or failure of a negotiation depended not only on the final offer on the table but also on the emerging dynamics of the bargaining process. More

A team of researchers from Bristol’s Quantum Engineering and Technology Labs (QETLabs) has shown how to protect qubits from errors using photons in a silicon chip.
Quantum computers are gaining pace. They promise to provide exponentially more computing power for certain very tricky problems. They do this by exploiting the peculiar behaviour of quantum particles, such as photons of light.
However, quantum states of particles are very fragile. The quantum bits, or qubits, that underpin quantum computing pick up errors very easily and are damaged by the environment of the everyday world. Fortunately, we know in principle how to correct for these errors.
Quantum error correcting codes are a method to protect, or to nurture, qubits, by embedding them in a more robust entangled state of many particles. Now a team led by researchers at Bristol’s Quantum Engineering and Technology Laboratories (QETLabs) has demonstrated this using a quantum photonic chip.
The team showed how large states of entangled photons can contain individual logical qubits and protect them from the harmful effects of the classical world. The Bristol-led team included researchers from DTU in Copenhagen who fabricated the chip.
Dr Caterina Vigliar, first author on the work, said: “The chip is really versatile. It can be programmed to deliver different kinds of entangled states called graphs. Each graph protects logical quantum bits of information from different environmental effects.”
Anthony Laing, co-Director of QETLabs, and an author on the work said: “Finding ways to efficiently deliver large numbers of error protected qubits is key to one day delivering quantum computers.”
Story Source:
Materials provided by University of Bristol. Note: Content may be edited for style and length. More

One third of children with a microdeletion of chromosome 22 will later develop a psychotic illness such as schizophrenia. But how do we know which of these children might be affected? Today, various studies have contributed to the understanding of the neurobiological mechanisms that are associated with the development of psychotic illnesses. The problem is that the ability to identify those at risk and adapt their treatment accordingly remains limited. Indeed, many variables — other than neurobiological — contribute to their development.
This is why a team from the University of Geneva (UNIGE) has joined forces with a team from the EPFL to use in a longitudinal manner an artificial intelligence tool: the network analysis method. This algorithm correlates many variables from different backgrounds — neurobiological, psychological, cognitive, etc. — over a period of twenty years, in order to determine which current symptoms are predictive of a psychotic illness in the child’s future developmental trajectory. These results, to be read in the journal eLife, will enable early treatment of children deemed to be at risk of developing psychological disorders, with the aim of preventing or even avoiding them.
One in 4,000 people have a microdeletion of chromosome 22, which can lead to the development of psychotic illnesses, such as schizophrenia, in adolescence. However, only one third of them will eventually be affected by a psychotic disorder. How can we determine which ones? “For the time being, the analyses are looking at the neurobiological mechanisms involved in psychological disorders, as well as the presence of certain symptoms that are assimilated to a psychological illness, without knowing which are the most relevant,” explains Corrado Sandini, a researcher at the Department of Psychiatry of UNIGE Faculty of Medicine, to the Fondation Pôle Autisme and first author of the study.
Not being able to take into account the degree of importance of each symptom can be problematic in predicting the course of the disease and providing the most appropriate treatment for the patient. “This is why we thought of using the network analysis method,” he continues. This methodology, which is currently used on adults, makes it possible to combine variables from completely different worlds in the same analysis space, while considering them individually. “Since the development of psychotic illnesses depends on many variables other than purely neurobiological ones, this algorithm would make it possible to highlight the most important symptoms to alert about the potential risks of a child becoming schizophrenic, for example,” says Stéphan Eliez, professor in the Department of Psychiatry at the UNIGE Faculty of Medicine and to the Fondation Pôle Autisme.
Finding the predictive symptoms
The Geneva team has joined forces with researchers at EPFL to develop this methodology and apply it to a cohort of children and adolescents suffering from a microdeletion of chromosome 22, some of whom have been followed for more than twenty years. “The aim is to adapt network analysis by tailoring it to young patients in a longitudinal manner, in order to obtain insightful statistics on highly intertwined variables throughout the child’s developmental trajectory,” emphasises Dimitri Van De Ville, a professor in the Department of Radiology and Medical Informatics at UNIGE Faculty bof Medicine and at the EPFL Institute of Bioengineering. The aim is to find the variables in childhood that will foresay the development of psychotic illnesses. “We will therefore know which battle to fight, thanks to key factors that will enable us to act where and, above all, when it is necessary,” explains Stéphan Eliez. “If we can identify them, we can try to regulate the symptom to reduce the risk of developing a psychotic illness later on.”
To test the methodology, 40 variables were taken into account for 70 children suffering from a microdeletion of chromosome 22, observed every three years from childhood to adulthood. “These variables included hallucinations, general mood, feelings of guilt and the management of daily stress,” explains Corrado Sandini. Questionnaires completed by parents also provided valuable data. Visual representations then shed light/highlighted/determined the most important variables that predict the development of psychological problems three years later. “We found that an anxious 10-year-old whose anxiety turns into an inability to cope with stress in adolescence is likely to develop a psychological illness. The evolution of anxiety is therefore a significant warning signal,” continues the Geneva researcher. Similarly, sadness, which over time becomes a feeling of guilt, is also a very important symptom.
A personalised method for each child
In order to confirm the results of their algorithm, the researchers applied it to other cohorts vulnerable to psychotic illnesses that have been followed for many years, and were thus able to confirm that the computer tool works. The aim is now to use it as a predictive tool, but also to refine it by integrating other variables, such as weight, to contribute to the clinical assessment. Finally, the interest of this method is obviously the prediction, with the aim of avoiding the disease, but above all its fully personalised quality that studies the developmental trajectory specific to each child. More

Scientists have shown that orangutan call signals believed to be closest to the precursors to human language, travel through forest over long distances without losing their meaning. This throws into question the accepted mathematical model on the evolution of human speech according to researchers from the University of Warwick.
The currently accepted model, developed by mathematicians, predicts that human ancestors strung sounds together in their calls in order to increase their chances of carrying a signal’s content to a recipient over distance. Because signal quality degrades over larger distances, it is proposed that human ancestors started linking sounds together to effectively convey a package of information even if it is distorted.
Researchers from the University of Warwick’s Department of Psychology set out to collect empirical data to investigate the model. They selected a range of sounds from previously collected audio recordings of orangutan communications. Specific consonant-like and vowel-like signals were played out and re-recorded across the rainforest at set distances of 25, 50, 75 and 100 metres. The quality and content of the signals received were analysed. The results are revealed in the study: Orangutan information broadcast via consonant-like and vowel-like calls breaches mathematical models of linguistic evolution published today in Biology Letters.
The team found that although the quality of the signal may have degraded, the content of the signal was still intact — even at long distance. In fact the informational characteristics of calls remained uncompromised until the signal became inaudible. This calls into question the existing and accepted theory of language development.
Dr Adriano Lameira, an evolutionary psychologist from the University of Warwick, led the study. He said:
“We used our bank of audio data recordings from our studies of orangutan in Indonesia. We selected the clear vowel-like and consonant-like signals and played them out and re-recorded them over measured distances in a rainforest setting. The purpose of this study was to look at the signals themselves and understand how they behaved as a package of information. This study is neat because it is only across distance that you can hope to assess this error limit theory — it disregards other aspects of communication like gestures, postures, mannerisms and facial expressions. More