physicsworld--2020-08-24--Moth-inspired robot swarms could soon sniff out harmful substances - Physics World

Inspired by the behaviour of moths , researchers have developed a novel collective search algorithm for locating the source of an odour .
Robots that mimic moth search patterns have been proposed before for the detection of harmful gases and volatile substances .
Now , research led Antonio Celani at the Abdus Salam International Centre for Theoretical Physics in Trieste suggests that this approach could be optimized by using a group of robots that collaborate to find a source .
Many animals rely on their sense of smell to navigate and locate resources .
Dispersal by turbulent air currents can @ @ @ @ @ @ @ animals have adapted behaviours to track odours .
One of the most extraordinary of these is observed in male moths .
When finding a mate , they must follow hormonal chemicals ( pheromones ) produced by females and they are able to do this successfully over distances of hundreds of metres .
Able to sense wind direction , and equipped with a keen sense of smell , moths employ a two-step “ cast and surge ” strategy to correct their motion .
When a moth detects pheromones it “ surges ” by flying @ @ @ @ @ @ @ scent , at which point it begins zigzagging ( casting ) at a 45° to the wind until it recovers the trail .
It is this process that , when incorporated into an algorithm , can drive gas detection robots .
Like most animals , moths do not work together to find a mate .
However , other animals such as fish and birds coordinate their movement in groups to increase the efficiency of their search for resources .
Celani and colleagues investigated whether modelling moths as flocking animals could give the same @ @ @ @ @ @ @ source – and by extension enhance the cast and surge algorithm .
In a flock , each agent has two forms of motion .
They react individually to their environment – in this case by performing cast and surge – and they move as a group by aligning with those around them .
This tendency to align is called “ collective motion ” and in its simplest form it is described by a model called the Vicsek algorithm .
Here each agent chooses a velocity by averaging that of their neighbours , so @ @ @ @ @ @ @ researchers combined the Vicsek and cast and surge algorithms and introduced a “ trust parameter ” ; a number between 0-1 to describe the balance between them .
When this parameter is 0 , the agents behave as individuals , and when it is 1 they purely follow the Vicsek model .
In simulations , agents were released a distance from a source of odour particles , which were dispersed in a turbulent velocity field .
The time taken for the first agent to reach the source was then calculated as a function @ @ @ @ @ @ @ simulated collective search in a range of environments by varying the speed , population and perception of the agents , as well as the odour emission rate and the velocity field fluctuations .
Across the simulations , a trend soon emerged .
There is an optimal trust parameter of around 0.8 where the search time is minimized , and the fastest agent behaves almost as if it already knows where the source is .
This is also the point where variations in the search time are smallest , with collective motion effectively “ @ @ @ @ @ @ @ conditions .
Describing their research in Physical Review E , the team highlights the effect of changing the odour particle emission rate ; reducing this parameter from 1 to 0.05 increases the search time of a single agent threefold but has almost no effect in the case of the optimized group .
This research demonstrates that incorporating collective motion into odour-tracking algorithms can not only make them faster , but also more flexible .
The algorithm ’ s robustness makes it a realistic candidate for further study , where it could advance the @ @ @ @ @ @ @ harmful , volatile chemicals and pollutants .

Super sniffer: a male pine processionary moth. (Courtesy: Alvesgaspar/CC BY-SA 4.0)
Inspired by the behaviour of moths, researchers have developed a novel collective search algorithm for locating the source of an odour. Robots that mimic moth search patterns have been proposed before for the detection of harmful gases and volatile substances. Now, research led Antonio Celani at the Abdus Salam International Centre for Theoretical Physics in Trieste suggests that this approach could be optimized by using a group of robots that collaborate to find a source.
Many animals rely on their sense of smell to navigate and locate resources. Dispersal by turbulent air currents can make this a difficult task and some animals have adapted behaviours to track odours. One of the most extraordinary of these is observed in male moths. When finding a mate, they must follow hormonal chemicals (pheromones) produced by females and they are able to do this successfully over distances of hundreds of metres.
Able to sense wind direction, and equipped with a keen sense of smell, moths employ a two-step “cast and surge” strategy to correct their motion. When a moth detects pheromones it “surges” by flying into the wind until it loses the scent, at which point it begins zigzagging (casting) at a 45° to the wind until it recovers the trail. It is this process that, when incorporated into an algorithm, can drive gas detection robots.
Collective motion meets cast and surge
Like most animals, moths do not work together to find a mate. However, other animals such as fish and birds coordinate their movement in groups to increase the efficiency of their search for resources. Celani and colleagues investigated whether modelling moths as flocking animals could give the same advantage in the search for an odour source – and by extension enhance the cast and surge algorithm.
In a flock, each agent has two forms of motion. They react individually to their environment – in this case by performing cast and surge – and they move as a group by aligning with those around them. This tendency to align is called “collective motion” and in its simplest form it is described by a model called the Vicsek algorithm. Here each agent chooses a velocity by averaging that of their neighbours, so that the group moves coherently.
The researchers combined the Vicsek and cast and surge algorithms and introduced a “trust parameter”; a number between 0-1 to describe the balance between them. When this parameter is 0, the agents behave as individuals, and when it is 1 they purely follow the Vicsek model.
In simulations, agents were released a distance from a source of odour particles, which were dispersed in a turbulent velocity field. The time taken for the first agent to reach the source was then calculated as a function of the trust parameter.
Optimizing trust
The researchers simulated collective search in a range of environments by varying the speed, population and perception of the agents, as well as the odour emission rate and the velocity field fluctuations. Across the simulations, a trend soon emerged. There is an optimal trust parameter of around 0.8 where the search time is minimized, and the fastest agent behaves almost as if it already knows where the source is. This is also the point where variations in the search time are smallest, with collective motion effectively “buffering” against changes to the simulation conditions.
Describing their research in Physical Review E, the team highlights the effect of changing the odour particle emission rate; reducing this parameter from 1 to 0.05 increases the search time of a single agent threefold but has almost no effect in the case of the optimized group.
This research demonstrates that incorporating collective motion into odour-tracking algorithms can not only make them faster, but also more flexible. The algorithm’s robustness makes it a realistic candidate for further study, where it could advance the use of robotics for the detection of harmful, volatile chemicals and pollutants.


physicsworld--2020-08-21--A matter of trust - Physics World

A matter of trust - Physics World

What a difference a few months can make .
When science historian Naomi Oreskes was writing her latest book Why Trust Science ?
a large part of the context seemed to be climate change .
Indeed , this is a topic on which she has previously exposed the deceits of denialists in her 2010 book with Erik Conway , Merchants of Doubt .
That problem remains : huge numbers of people continue to ignore or deny the stark facts that science – and indeed experience – confronts us with : the world is warming dangerously fast and is likely to @ @ @ @ @ @ @ .
But suddenly the most pressing scientific issue is another one entirely : the global COVID-19 pandemic .
Whereas the scientific evidence on climate change warns of serious perils , including massive social disruption and fatality , within decades , for COVID-19 those things came upon us in a matter of weeks .
While it would be unwise to draw the parallels too closely , the pandemic has become a lens that focuses many of the same issues about why , when and how to trust science ; and reading Oreskes ’ arguments @ @ @ @ @ @ @ from a series of lectures Oreskes gave at Princeton University , and incorporating essay-length responses by experts from several disciplines , the book begins with a primer on the philosophy of science that all scientists would do well to read .
Many still labour under the conviction that the philosophical foundation of their enterprise is either Karl Popper ’ s notion of falsifiability ( theories can never be proved , only disproved ) or Thomas Kuhn ’ s concept of paradigm shifts .
But philosophers of science have long recognized the shortcomings of @ @ @ @ @ @ @ the pragmatic view that science is a makeshift affair , beyond any one universal “ method ” , that nevertheless mostly works well enough to generate knowledge proved reliable by experience .
Oreskes explains how that happens – and why sometimes it goes awry .
In certain cases – such as the 19th-century “ limited energy ” theory that “ explained ” why higher education was not good for women , eugenics and the recent controversy about the efficacy of dental flossing – she explains both the social and technical factors that can @ @ @ @ @ @ @ that science as a whole has enough error-correcting mechanisms and a good enough track record to warrant public trust .
Reliable knowledge , she says , is produced by five factors : crucially , method and evidence , but also consensus , values and humility .
When science has gone astray , it is often because of powerful scientists who lacked the humility to listen to all the evidence .
The inclusion here of “ values ” might surprise some – but it shouldn ’ t .
The popular idea that science is @ @ @ @ @ @ @ of science ’ s history .
Besides , acknowledgement of values is vital to social dialogue .
Scientists , says Oreskes , “ have made the mistake of thinking that people would trust them if they believed that science was value-free ” .
On the contrary , people are often more ready to listen to others with whom they can see some shared values .
It ’ s well attested that people are less suspicious of medical innovations when told they have been developed to solve specific health problems , rather than just @ @ @ @ @ @ @ also dismantles the notion that science is a meritocracy that rewards only excellence , and has no need of initiatives for diversity and inclusion .
She points out that diversity of viewpoint is precisely what can make science so powerful – and shows how several past errors , especially in the science of “ race ” and gender , were highlighted by precisely those groups who suffered from them .
Although always readable , Why Trust Science ?
is not pitched in a manner that seems likely to convert antivaxxers and climate-change deniers @ @ @ @ @ @ @ goal .
It ’ s better to see the book as an aid to scientists and their advocates .
The sometimes-shrill insistence from scientists that they have a perfectly designed , intellectually rigorous truth-generating machine is not only philosophically unconvincing , but demonstrably false .
As Oreskes argues , the thing that discomfits many scientists – that science is a social process – is actually its real strength .
For instance , those who seek to undermine scientific findings by claiming that consensus has no place in science are wrong ; it is @ @ @ @ @ @ @ – a “ social condition ” – matters .
“ We use consensus as a proxy because we have no way to know , for sure , what the truth is , ” Oreskes writes .
And it really is not hard to spot when consensus arises among trustworthy experts .
“ Most climate-change deniers are not climate scientists , and…objections to evolutionary theory largely emerge from non-scientific domains ” , she points out .
Sure , conflicts of interest – climate-change deniers funded by oil companies – can be hidden , but @ @ @ @ @ @ @ weigh heavily on the balance of our judgements .
We should trust scientists just as we do other experts , such as plumbers and dentists : not because they have a hotline to truth , but because they have been specifically trained to do their job , which is “ studying the natural world and sorting out the complex issues that arise in it ” .
( There are bad plumbers and dentists , but plumbing and dentistry still work . )
The idea “ that scientists follow a magic formula ( ‘ @ @ @ @ @ @ @ results ” , Oreskes says , “ persists in textbooks and in the popular imagination , but it does not stand up to historical scrutiny .
What does stand up is a portrait of science as a communal activity of experts , who use diverse methods to gather empirical evidence , and critically vet claims deriving from it.
” It is this social process , she says , that enables science to do that rather marvellous thing of producing both stability and novelty .
And we shouldn ’ t exaggerate the problem of @ @ @ @ @ @ @ conspiracy theories about the 5G network and bioweapons , there is no massive anti-science sentiment out there .
Most people are desperate to know what “ the science ” is saying about the pandemic , and will be delighted to see a vaccine .
As science historian Susan Lindee points out in her essay , most people do trust science on the whole – they just don ’ t always realize it .
Indeed , scientists have so determinedly separated technology from science , for rhetorical reasons , that people don ’ t @ @ @ @ @ @ @ entails trust in science .
Climate-change scepticism , then , is not the same as generalized science-denial .
As the overlap between that group and those questioning scientific expertise on COVID-19 has revealed , this is not about ignorance but ideology – it signals a difference in values .
( Lockdown and mask-wearing , like climate action , seems to constrain the liberty to do as you please . )
The problem with getting someone like Donald Trump ( or at least , many of his supporters ; Trump himself defies categorization as @ @ @ @ @ @ @ is almost orthogonal to the question of whether he “ trusts ” it or not .
So when science is traduced or ignored , the answer is not to formulate an airtight philosophical argument for its veracity .
That problem is vastly complex , connected for example to cognitive biases , access to information , political tribalism and the boundless human capacity for self-deception .
It needs to be understood as a social , psychological and political issue .
All this is far too much to be tackled in so short a text @ @ @ @ @ @ @ of showing scientists and their advocates where they might usefully focus their energies .

Physics World. Members of the Institute of Physics can enjoy the full issue Taken from the August 2020 issue of. Members of the Institute of Physics can enjoy the full issue via the Physics World app
Philip Ball reviews Why Trust Science? by Naomi Oreskes
Scientific value(s) Naomi Oreskes’ book about trust in science refers often to climate change, but many of the same lessons can be applied to the public and political responses to COVID-19. (Courtesy: iStock/hocus-focus)
What a difference a few months can make. When science historian Naomi Oreskes was writing her latest book Why Trust Science? a large part of the context seemed to be climate change. Indeed, this is a topic on which she has previously exposed the deceits of denialists in her 2010 book with Erik Conway, Merchants of Doubt. That problem remains: huge numbers of people continue to ignore or deny the stark facts that science – and indeed experience – confronts us with: the world is warming dangerously fast and is likely to change catastrophically unless urgent action is taken.
But suddenly the most pressing scientific issue is another one entirely: the global COVID-19 pandemic. Whereas the scientific evidence on climate change warns of serious perils, including massive social disruption and fatality, within decades, for COVID-19 those things came upon us in a matter of weeks. While it would be unwise to draw the parallels too closely, the pandemic has become a lens that focuses many of the same issues about why, when and how to trust science; and reading Oreskes’ arguments in this light is eye-opening.
Arising from a series of lectures Oreskes gave at Princeton University, and incorporating essay-length responses by experts from several disciplines, the book begins with a primer on the philosophy of science that all scientists would do well to read. Many still labour under the conviction that the philosophical foundation of their enterprise is either Karl Popper’s notion of falsifiability (theories can never be proved, only disproved) or Thomas Kuhn’s concept of paradigm shifts. But philosophers of science have long recognized the shortcomings of both frameworks, and many now take the pragmatic view that science is a makeshift affair, beyond any one universal “method”, that nevertheless mostly works well enough to generate knowledge proved reliable by experience.
Oreskes explains how that happens – and why sometimes it goes awry. In certain cases – such as the 19th-century “limited energy” theory that “explained” why higher education was not good for women, eugenics and the recent controversy about the efficacy of dental flossing – she explains both the social and technical factors that can distort the evidence. But Oreskes argues that science as a whole has enough error-correcting mechanisms and a good enough track record to warrant public trust. Reliable knowledge, she says, is produced by five factors: crucially, method and evidence, but also consensus, values and humility. When science has gone astray, it is often because of powerful scientists who lacked the humility to listen to all the evidence.
The inclusion here of “values” might surprise some – but it shouldn’t. The popular idea that science is “value-free” flies in the face of science’s history. Besides, acknowledgement of values is vital to social dialogue. Scientists, says Oreskes, “have made the mistake of thinking that people would trust them if they believed that science was value-free”. On the contrary, people are often more ready to listen to others with whom they can see some shared values. It’s well attested that people are less suspicious of medical innovations when told they have been developed to solve specific health problems, rather than just “because we can”.
Oreskes also dismantles the notion that science is a meritocracy that rewards only excellence, and has no need of initiatives for diversity and inclusion. She points out that diversity of viewpoint is precisely what can make science so powerful – and shows how several past errors, especially in the science of “race” and gender, were highlighted by precisely those groups who suffered from them.
Although always readable, Why Trust Science? is not pitched in a manner that seems likely to convert antivaxxers and climate-change deniers – but that is not really its goal. It’s better to see the book as an aid to scientists and their advocates. The sometimes-shrill insistence from scientists that they have a perfectly designed, intellectually rigorous truth-generating machine is not only philosophically unconvincing, but demonstrably false. As Oreskes argues, the thing that discomfits many scientists – that science is a social process – is actually its real strength. For instance, those who seek to undermine scientific findings by claiming that consensus has no place in science are wrong; it is precisely because science is fallible that consensus – a “social condition” – matters. “We use consensus as a proxy because we have no way to know, for sure, what the truth is,” Oreskes writes.
And it really is not hard to spot when consensus arises among trustworthy experts. “Most climate-change deniers are not climate scientists, and…objections to evolutionary theory largely emerge from non-scientific domains”, she points out. Sure, conflicts of interest – climate-change deniers funded by oil companies – can be hidden, but rarely very well. And they should weigh heavily on the balance of our judgements. We should trust scientists just as we do other experts, such as plumbers and dentists: not because they have a hotline to truth, but because they have been specifically trained to do their job, which is “studying the natural world and sorting out the complex issues that arise in it”. (There are bad plumbers and dentists, but plumbing and dentistry still work.)
The idea “that scientists follow a magic formula (‘the scientific method’) that guarantees results”, Oreskes says, “persists in textbooks and in the popular imagination, but it does not stand up to historical scrutiny. What does stand up is a portrait of science as a communal activity of experts, who use diverse methods to gather empirical evidence, and critically vet claims deriving from it.” It is this social process, she says, that enables science to do that rather marvellous thing of producing both stability and novelty.
And we shouldn’t exaggerate the problem of trust. Despite all the crazed COVID-19 conspiracy theories about the 5G network and bioweapons, there is no massive anti-science sentiment out there. Most people are desperate to know what “the science” is saying about the pandemic, and will be delighted to see a vaccine. As science historian Susan Lindee points out in her essay, most people do trust science on the whole – they just don’t always realize it. Indeed, scientists have so determinedly separated technology from science, for rhetorical reasons, that people don’t even appreciate that a faith in iPhones entails trust in science.
Climate-change scepticism, then, is not the same as generalized science-denial. As the overlap between that group and those questioning scientific expertise on COVID-19 has revealed, this is not about ignorance but ideology – it signals a difference in values. (Lockdown and mask-wearing, like climate action, seems to constrain the liberty to do as you please.) The problem with getting someone like Donald Trump (or at least, many of his supporters; Trump himself defies categorization as well as belief) to heed science is almost orthogonal to the question of whether he “trusts” it or not.
So when science is traduced or ignored, the answer is not to formulate an airtight philosophical argument for its veracity. That problem is vastly complex, connected for example to cognitive biases, access to information, political tribalism and the boundless human capacity for self-deception. It needs to be understood as a social, psychological and political issue. All this is far too much to be tackled in so short a text, but Oreskes does an excellent job of showing scientists and their advocates where they might usefully focus their energies.
2019 Princeton University Press £22hb 376pp


physicsworld--2020-08-25--Calls for UK and EU to compromise over Horizon Europe - Physics World

Rapid progress is needed in negotiations regarding the UK ’ s participation in the EU ’ s major scientific framework programme if collaborations are to continue smoothly into 2021 .
That is according to a statement signed by more than 100 organizations and individuals representing the European scientific community .
Together , they urge the EU and the UK to compromise on the UK ’ s participation in Horizon Europe – the successor to the €80bn Horizon 2020 programme .
The signatories say that while it is encouraging that both the EU and the UK have committed in principle to @ @ @ @ @ @ @ major sticking points remain .
They add that with good faith , agreement on the terms of participation should be possible , but warn that time is running out .
Anton Zensus , director at the Max Planck Institute for Radio Astronomy in Bonn , Germany , who signed the statement , told Physics World that there is real concern that the UK will lose its place in Horizon Europe .
“ There are only a few months left , and little progress toward an agreement has been reached so far , ” @ @ @ @ @ @ @ increasing with every day of unsuccessful negotiations.
” The signatories argue that association via Horizon Europe , which runs from 2021 to 2027 , should be “ a core part of the future relationship between the EU and the UK for research , underpinning valuable scientific partnerships that have been built up over many years ” .
In the statement they suggest several solutions to the issues that are still hindering negotiations .
One is that the UK needs to demonstrate its commitment by explicitly setting aside additional funding for full association for @ @ @ @ @ @ @ They also argue that the EU needs to introduce a two-way correction mechanism for balancing substantial disparities between contributions and receipts from the programme .
Currently , the EU text includes a mechanism to ensure the UK can not be a net beneficiary of programme funding but does not protect the UK from making contributions that exceed its financial return .
The signatories claim that this is likely to create an imbalance that would be too much for the UK to reasonably pay .
The UK also needs to accept the need for @ @ @ @ @ @ @ of programme funds , while the EU should confirm that the UK can exploit research results as it wishes .
Finally , the signatories call for both sides to agree reciprocal arrangements to support the mobility of researchers participating in Horizon Europe funded work .
“ Horizon Europe is the Champions League of research and there is no doubt that UK football clubs will continue to play in the Champions League , ” Zensus told Physics World .
“ UK researchers have always benefited from the competition with their European counterparts .
I @ @ @ @ @ @ @ outweighed the financial ones and I predict this will also be the case in a future collaboration .
”

Let’s stay together: More than 100 organizations and individuals from the European scientific community have called on the UK and EU to agree terms for the UK’s membership of Horizon Europe. (Courtesy: Shutterstock)
Rapid progress is needed in negotiations regarding the UK’s participation in the EU’s major scientific framework programme if collaborations are to continue smoothly into 2021. That is according to a statement signed by more than 100 organizations and individuals representing the European scientific community. Together, they urge the EU and the UK to compromise on the UK’s participation in Horizon Europe – the successor to the €80bn Horizon 2020 programme.
The signatories say that while it is encouraging that both the EU and the UK have committed in principle to UK participation in the research programme, major sticking points remain. They add that with good faith, agreement on the terms of participation should be possible, but warn that time is running out. Anton Zensus, director at the Max Planck Institute for Radio Astronomy in Bonn, Germany, who signed the statement, told Physics World that there is real concern that the UK will lose its place in Horizon Europe. “There are only a few months left, and little progress toward an agreement has been reached so far,” he explains. “This risk is increasing with every day of unsuccessful negotiations.”
Horizon Europe is the Champions League of research and there is no doubt that UK football clubs will continue to play in the Champions League Anton Zensus
The signatories argue that association via Horizon Europe, which runs from 2021 to 2027, should be “a core part of the future relationship between the EU and the UK for research, underpinning valuable scientific partnerships that have been built up over many years”. In the statement they suggest several solutions to the issues that are still hindering negotiations. One is that the UK needs to demonstrate its commitment by explicitly setting aside additional funding for full association for Horizon Europe in its science budget.
They also argue that the EU needs to introduce a two-way correction mechanism for balancing substantial disparities between contributions and receipts from the programme. Currently, the EU text includes a mechanism to ensure the UK cannot be a net beneficiary of programme funding but does not protect the UK from making contributions that exceed its financial return. The signatories claim that this is likely to create an imbalance that would be too much for the UK to reasonably pay. The UK also needs to accept the need for EU institutions to oversee the correct use of programme funds, while the EU should confirm that the UK can exploit research results as it wishes. Finally, the signatories call for both sides to agree reciprocal arrangements to support the mobility of researchers participating in Horizon Europe funded work.
“Horizon Europe is the Champions League of research and there is no doubt that UK football clubs will continue to play in the Champions League,” Zensus told Physics World. “UK researchers have always benefited from the competition with their European counterparts. I would say the scientific benefits have always outweighed the financial ones and I predict this will also be the case in a future collaboration.”


physicsworld--2020-08-25--Global mentoring scheme fosters future leaders in medical physics - Physics World

Mentoring – providing support and guidance to someone less experienced to help their professional and personal development – can help progress the mentee ’ s studies , increase their confidence , and inspire and motivate them to reach their career goals .
In medical physics , where trainees must learn to work , research and interact with other professionals in a complex healthcare environment , mentoring could prove particularly valuable .
As both a science and a health profession , medical physics has a specific set of challenges .
It calls for more than just excellent scientific abilities , with @ @ @ @ @ @ @ medical physicists eyeing professional success in the hospital environment .
With this task in mind , Kwan Hoong Ng from the University of Malaya helped set up a global mentoring programme , Medical Physics : Leadership & Mentoring , to provide young medical physicists with guidance and support and help them to develop leadership roles .
“ I have always been interested in helping and encouraging young people in their studies , career and life in general .
I would like to see them assume leadership one day , ” Ng explains .
@ @ @ @ @ @ @ pioneers , both within and outside medical physics , as mentors .
These are people who have contributed to advances in healthcare through the application of physics to research , education and clinical practice.
” Writing in Physica Medica , a group of early-career medical physics professionals describe their personal experiences of participating in this programme .
The study investigated the impact of this experience on their lives and careers and evaluated the importance of mentoring for young clinical and academic medical physicists .
The programme comprised one permanent mentor ( Ng ) @ @ @ @ @ @ @ America and Asia .
The mentees included medical physicists , postgraduate students and an early-career researcher , most of whom were working in radio-diagnostics or radiotherapy .
Ng notes that he was supported at the start by Robert Jeraj , Eva Bezak and Tomas Kron , while additional mentors from several countries and institutions also joined the group to take part in discussions , share experiences and provide advice about a professional career in medical physics .
To address the geographic constraints , the programme employed “ e-mentoring ” , with video meetings @ @ @ @ @ @ @ establish relationships between mentors and mentees from different areas and countries .
This approach is particularly useful for supporting young professionals in developing countries .
“ In developing countries , medical physics is just starting to develop .
There is a lack of experienced seniors to guide and mentor early-career medical physicists , ” Ng explains .
“ Leadership qualities are not being introduced and emphasized in academic programmes .
There is therefore an urgent and crucial need to mentor them to be leaders and contribute to clinical service and research.
” To @ @ @ @ @ @ @ global mentoring scheme , all mentees in the group completed an online survey .
Most of the group ( 81.3 % ) reported that the programme had a positive impact on both their personal and professional lives .
One of the main activities involved invited speakers ( the temporary mentors ) sharing knowledge of their area of expertise or professional experiences .
Here , the mentees preferred to hear talks about the mentors ’ personal experiences and leadership advice , rather than medical physics techniques .
One positive outcome of such interactions was @ @ @ @ @ @ @ communicated with mentors outside of these group meetings .
“ I would like to see mentor and mentee develop a lifelong partnership , ” Ng points out .
Most mentees said that taking part in the programme had improved their leadership skills .
And all of them believed that , on some level , participation changed their behaviour in challenging times and helped them to make decisions about their career .
Most also agreed that the mentors served as role models for their professional careers .
The mentees were also encouraged to focus @ @ @ @ @ @ @ conference participation .
Half of the participants published at least one manuscript , with help or involvement of the mentors as co-author , while about 45 % gave at least one conference presentation .
For example , an initiative of female mentees , guided by one mentor , wrote an article entitled “ Women in physics : pioneers who inspire us ” .
Overall , participants in the mentoring group had nothing but positive impressions , concluding that the programme was beneficial to their careers and personal growth and should be encouraged .
@ @ @ @ @ @ @ be implemented as an extracurricular activity whenever possible .
“ Leadership and mentoring of medical physicists is essential to produce future innovative leaders , ” says Ng .
“ This programme also promotes gender balance and equality , collaboration and intercultural understanding among the mentees .
These are important features .
The human values are also much appreciated by the mentees.
” As such , the team plans to expand and diversify the scheme with the participation of medical physicists from other continents , such as Africa and Europe .
“ This programme @ @ @ @ @ @ @ more people to join us , ” Ng tells Physics World .

Mentor Kwan Hoong Ng (centre) at the University of São Paulo (USP) in Brazil, with USP faculty and some of the first mentees who participated in the global medical physics mentoring programme.
Mentoring – providing support and guidance to someone less experienced to help their professional and personal development – can help progress the mentee’s studies, increase their confidence, and inspire and motivate them to reach their career goals. In medical physics, where trainees must learn to work, research and interact with other professionals in a complex healthcare environment, mentoring could prove particularly valuable.
As both a science and a health profession, medical physics has a specific set of challenges. It calls for more than just excellent scientific abilities, with leadership skills another key requirement for burgeoning medical physicists eyeing professional success in the hospital environment. With this task in mind, Kwan Hoong Ng from the University of Malaya helped set up a global mentoring programme, Medical Physics: Leadership & Mentoring, to provide young medical physicists with guidance and support and help them to develop leadership roles.
“I have always been interested in helping and encouraging young people in their studies, career and life in general. I would like to see them assume leadership one day,” Ng explains. “The programme brings in leaders and pioneers, both within and outside medical physics, as mentors. These are people who have contributed to advances in healthcare through the application of physics to research, education and clinical practice.”
Writing in Physica Medica, a group of early-career medical physics professionals describe their personal experiences of participating in this programme. The study investigated the impact of this experience on their lives and careers and evaluated the importance of mentoring for young clinical and academic medical physicists.
Expert guidance
The programme comprised one permanent mentor (Ng) and 16 mentees from countries in Latin America and Asia. The mentees included medical physicists, postgraduate students and an early-career researcher, most of whom were working in radio-diagnostics or radiotherapy. Ng notes that he was supported at the start by Robert Jeraj, Eva Bezak and Tomas Kron, while additional mentors from several countries and institutions also joined the group to take part in discussions, share experiences and provide advice about a professional career in medical physics.
Left to right: mentors Kwan Hoong Ng, Robert Jeraj, Eva Bezak and Tomas Kron.
To address the geographic constraints, the programme employed “e-mentoring”, with video meetings and online group conference calls used to establish relationships between mentors and mentees from different areas and countries. This approach is particularly useful for supporting young professionals in developing countries.
“In developing countries, medical physics is just starting to develop. There is a lack of experienced seniors to guide and mentor early-career medical physicists,” Ng explains. “Leadership qualities are not being introduced and emphasized in academic programmes. There is therefore an urgent and crucial need to mentor them to be leaders and contribute to clinical service and research.”
Analysing the outcome
To evaluate their experiences of participating in this global mentoring scheme, all mentees in the group completed an online survey. Most of the group (81.3%) reported that the programme had a positive impact on both their personal and professional lives.
One of the main activities involved invited speakers (the temporary mentors) sharing knowledge of their area of expertise or professional experiences. Here, the mentees preferred to hear talks about the mentors’ personal experiences and leadership advice, rather than medical physics techniques. One positive outcome of such interactions was that more than half of the mentees communicated with mentors outside of these group meetings. “I would like to see mentor and mentee develop a lifelong partnership,” Ng points out.
Most mentees said that taking part in the programme had improved their leadership skills. And all of them believed that, on some level, participation changed their behaviour in challenging times and helped them to make decisions about their career. Most also agreed that the mentors served as role models for their professional careers.
The mentees were also encouraged to focus on skills such as article writing and conference participation. Half of the participants published at least one manuscript, with help or involvement of the mentors as co-author, while about 45% gave at least one conference presentation. For example, an initiative of female mentees, guided by one mentor, wrote an article entitled “Women in physics: pioneers who inspire us”.
Overall, participants in the mentoring group had nothing but positive impressions, concluding that the programme was beneficial to their careers and personal growth and should be encouraged. They recommend that mentoring for leadership should be implemented as an extracurricular activity whenever possible.
“Leadership and mentoring of medical physicists is essential to produce future innovative leaders,” says Ng. “This programme also promotes gender balance and equality, collaboration and intercultural understanding among the mentees. These are important features. The human values are also much appreciated by the mentees.”
As such, the team plans to expand and diversify the scheme with the participation of medical physicists from other continents, such as Africa and Europe. “This programme is gaining traction and we are getting more people to join us,” Ng tells Physics World.


physicsworld--2020-08-25--Acoustic metamaterials and machine learning beat the diffraction limit - Physics World

A system that reconstructs and classifies acoustic images with far smaller features than the wavelength of sound they emit has been developed by Bakhtiyar Orazbayev and Romain Fleury at the Swiss Federal Institute of Technology in Lausanne .
Their technique beats the diffraction limit by combining a metamaterial lens with machine learning and could be adapted to work with light .
The research could lead to new advances in image analysis and object classification , particularly in biomedical imaging .
The diffraction limit is a fundamental constraint on using light or sound waves to image tiny objects .
If the @ @ @ @ @ @ @ about half the wavelength of the light or sound used , then the features can not be resolved using conventional techniques .
One way of beating the diffraction limit is to use near-field waves that only propagate very short distances from an illuminated object and carry subwavelength spatial information .
Metamaterial lenses have been used to amplify near-field waves , allowing them to propagate over longer distances in imaging systems .
However , this approach is prone to heavy losses , resulting in noisy final images .
In their study , Orazbayev and @ @ @ @ @ @ @ combining it with machine learning – through which neural networks can be trained to discover intricate hidden structures within large , complex datasets .
The duo first trained a neural network with a database of 70,000 variations of the digits 0-9 .
They then displayed the digits acoustically using an 8X8 array of loudspeakers measuring 25 cm across , with the amplitude of each speaker representing the brightness of one pixel .
In addition , they placed a lossy metamaterial lens in front of the speaker array , consisting of a cluster of @ @ @ @ @ @ @ .
These structures acted as resonant cavities , which coupled to the decaying near-field waves to amplify them over long distances .
With an array of microphones placed several metres away , Orazbayev and Fleury picked up the amplitudes and phases of the resulting waves , which they fed into two separate variations of their neural network : one to reconstruct the images , and the other to classify specific digits .
Even when the most subtle features of the displayed digits were 30 times smaller than the wavelength of sound emitted by @ @ @ @ @ @ @ to classify images they had never seen before to within an accuracy of almost 80 % .
Orazbayev and Fleury now hope to implement their technique using light waves .
This will allow them to apply their neural networks to cellular-scale biological structures ; quickly producing high-resolution images with little required processing power .
If achieved , such a technique could open new opportunities for biomedical imaging , with potential applications ranging from cancer detection to early pregnancy tests .
The research is described in Physical Review X .

Sound system: photograph showing the array of loudspeakers on the far left. Also visible are the metamaterial lens of plastic spheres and the microphones used to acquire the images. (Courtesy: Bakhtiyar Orazbayev/EPFL)
A system that reconstructs and classifies acoustic images with far smaller features than the wavelength of sound they emit has been developed by Bakhtiyar Orazbayev and Romain Fleury at the Swiss Federal Institute of Technology in Lausanne. Their technique beats the diffraction limit by combining a metamaterial lens with machine learning and could be adapted to work with light. The research could lead to new advances in image analysis and object classification, particularly in biomedical imaging.
The diffraction limit is a fundamental constraint on using light or sound waves to image tiny objects. If the separation between two features is smaller than about half the wavelength of the light or sound used, then the features cannot be resolved using conventional techniques.
One way of beating the diffraction limit is to use near-field waves that only propagate very short distances from an illuminated object and carry subwavelength spatial information. Metamaterial lenses have been used to amplify near-field waves, allowing them to propagate over longer distances in imaging systems. However, this approach is prone to heavy losses, resulting in noisy final images.
Hidden structures
In their study, Orazbayev and Fleury improved on this metamaterial technique by combining it with machine learning – through which neural networks can be trained to discover intricate hidden structures within large, complex datasets.
The duo first trained a neural network with a database of 70,000 variations of the digits 0-9. They then displayed the digits acoustically using an 8X8 array of loudspeakers measuring 25 cm across, with the amplitude of each speaker representing the brightness of one pixel. In addition, they placed a lossy metamaterial lens in front of the speaker array, consisting of a cluster of sub-wavelength plastic spheres (see figure). These structures acted as resonant cavities, which coupled to the decaying near-field waves to amplify them over long distances.
With an array of microphones placed several metres away, Orazbayev and Fleury picked up the amplitudes and phases of the resulting waves, which they fed into two separate variations of their neural network: one to reconstruct the images, and the other to classify specific digits. Even when the most subtle features of the displayed digits were 30 times smaller than the wavelength of sound emitted by the speakers, the algorithms were able to classify images they had never seen before to within an accuracy of almost 80%.
Orazbayev and Fleury now hope to implement their technique using light waves. This will allow them to apply their neural networks to cellular-scale biological structures; quickly producing high-resolution images with little required processing power. If achieved, such a technique could open new opportunities for biomedical imaging, with potential applications ranging from cancer detection to early pregnancy tests.
The research is described in Physical Review X.


physicsworld--2020-08-27--A grasshopper’s quantum leap, mentoring medical physicists, extremely brilliant synchrotron - Physic

A grasshopper’s quantum leap, mentoring medical physicists, extremely brilliant synchrotron - Physics World

A grasshopper lands at a random location on a patch of lawn and then jumps a fixed distance in a @ @ @ @ @ of lawn has the highest probability of retaining the grasshopper after its jump ?
In @ @ @ @ @ World Weekly podcast , we talk to a quartet of physicists and mathematicians who have @ @ @ @ @ this “ grasshopper problem ” and Bell ’ s theorem of quantum physics .
We @ @ @ @ @ programme for mentoring medical physicists and the recent €150 million upgrade to the European Synchrotron @ @ @ @ @ guests are quantum grasshopper experts Olga Goulko , Adrian Kent , Dmitry Chistikov and Mike @ @

Explore the ways in which today’s world relies on AI, and ponder how this technology might shape the world of tomorrow


physicsworld--2020-08-27--Quantum error correction achieved using oscillator grid states - Physics World

A practical implementation of a quantum error correction protocol first proposed back in 2001 has been achieved by physicists in the US and France .
The protocol increases the coherence time of quantum memory and although the work is still preliminary , it could potentially allow for the much more economical use of quantum bits ( qubits ) in quantum computers .
Noise is inevitable in any system , and conventional computers use error correction to stop noise from corrupting calculations .
In quantum computers , noise-related errors are a much more significant problem because of the delicate nature of @ @ @ @ @ @ @ .
Errors in a quantum computer come from fundamentally classical sources , explains Michel Devoret of Yale University in Connecticut : “ The computation is derailed by parasitic noise or thermal noise ” .
However , fixing errors is not a simple matter : “ When you are repairing errors , you may introduce new errors because measurement is invasive in quantum mechanics ” .
The key to overcoming this problem lies in the fact that noise is local – it does not affect different parts of a system in a non-random way @ @ @ @ @ @ @ , therefore , it should be possible to recover it .
Most quantum error correction algorithms do this by using multiple qubits to encode the same information .
This is not a panacea , however , because increasing the number of qubits in a quantum computer is not easy .
Google ’ s Sycamore machine , with which it claimed quantum advantage in 2019 , contained just 54 qubits – for example .
Back in 2001 , theoretical physicists Daniel Gottesman , Alexei Kitaev and John Preskill proposed storing information non-locally in exotic @ @ @ @ @ @ @ known as GKP states : “ Everybody knows that the uncertainty principle says you can ’ t measure with arbitrary precision both the position and the momentum of a harmonic oscillator , ” explains Preskill , who is at Caltech .
“ But it turns out that you can prepare a state of a particle or an oscillator , and someone – while your back is turned – can come along and shift it a little in position and momentum , and you can measure both shifts to arbitrary accuracy if you promise @ @ @ @ @ @ @ look at one of these states in position space it looks like a grid , and if you look at it in momentum space it looks the same way , so if you shift the comb by less than half the distance between the teeth , you can measure the distance by which it ’ s been shifted .
So you can encode information in these states and the noise in the lab can be measured and corrected.
” When the trio first published their results , Devoret says the paper received only @ @ @ @ @ @ @ paper to be a wonderful example of a visionary theoretical discovery happening a little too early , ” he says .
“ I remember reading this paper and thinking ‘ Well this looks very clever but not very practical.
’ ” Since 2001 , however , researchers have become more adept at creating exotic quantum states in various platforms .
Moreover , they have realized that , as well as correcting for small displacements in position and momentum , GKP states can also compensate more effectively than any other states for the much @ @ @ @ @ @ @ from qubit states .
Last year , researchers at ETH Zurich in Switzerland created GKP states in qubits made of trapped ions , which are a leading contender for practical quantum computers .
Now , Devoret and colleagues at Yale and the Inria Paris Research Centre , have demonstrated quantum error correction of an encoded qubit in the other leading quantum computing technology – qubits made from superconducting circuits .
The researchers initialized qubits in specific states and measured their lifetimes with and without applying the quantum error correction algorithm .
They found @ @ @ @ @ @ @ lifetime of all the quantum states to around 250 μs .
“ In our experiment we ’ re just protecting memory , ” says Devoret , “ The next step is to show fault-tolerant computation : you want to protect an operation and error correct while you are computing ” .
Preskill is impressed : “ Up until now they ’ ve only demonstrated a fairly modest improvement over what they can do without using these special error-resistant states , ” he says , “ but it ’ s an important step.
” @ @ @ @ @ @ @ Santa Barbara adds , “ I think it ’ s a really interesting [ achievement ] and a step forward for the field because they made this error-protected logical qubit using ideas that have been around for a long time .
They showed it worked.
” Martinis , who until recently worked at Google ’ s AI lab developing quantum computers , cautions however , that radical improvements may be necessary to compete with the brute force approach : “ If you look at the technology of computers , we know that , @ @ @ @ @ @ @ make lots of bits – so we can make lots of qubits .
The advantage here is that you do this error correction internally using one qubit with a complicated state , so you don ’ t necessarily have to scale up , but unless you extend the lifetime thousands or millions of times , how useful is it going to be ?
’ The research is described in Nature .

On grid: oscillator grid states have been used to do quantum error correction in a superconducting qubit. (Courtesy: Shutterstock/Dmitriy-Rybin)
A practical implementation of a quantum error-correction protocol first proposed back in 2001 has been achieved by physicists in the US and France. The protocol increases the coherence time of quantum memory and although the work is still preliminary, it could potentially allow for the much more economical use of quantum bits (qubits) in quantum computers.
Noise is inevitable in any system, and conventional computers use error correction to stop noise from corrupting calculations. In quantum computers, noise-related errors are a much more significant problem because of the delicate nature of the quantum states used to create qubits.
Errors in a quantum computer come from fundamentally classical sources, explains Michel Devoret of Yale University in Connecticut: “The computation is derailed by parasitic noise or thermal noise.” However, fixing errors is not a simple matter. “When you are repairing errors, you may introduce new errors because measurement is invasive in quantum mechanics,” says Devoret.
Non-local solution
The key to overcoming this problem lies in the fact that noise is local – it does not affect different parts of a system in a non-random way. If quantum information is stored non-locally, therefore, it should be possible to recover it. Most quantum error-correction algorithms do this by using multiple qubits to encode the same information. This is not a panacea, however, because increasing the number of qubits in a quantum computer is not easy. For example, Google’s Sycamore machine, with which it claimed quantum advantage in 2019, contained just 54 qubits.
Back in 2001, theoretical physicists Daniel Gottesman, Alexei Kitaev and John Preskill proposed storing information non-locally in exotic quantum states of an oscillator that became known as GKP states. “Everybody knows that the uncertainty principle says you can’t measure with arbitrary precision both the position and the momentum of a harmonic oscillator,” explains Preskill, who is at Caltech. “But it turns out that you can prepare a state of a particle or an oscillator, then someone – while your back is turned – can come along and shift it a little in position and momentum, and you can measure both shifts to arbitrary accuracy if you promise that they are small. If you look at one of these states in position space it looks like a grid, and if you look at it in momentum space it looks the same way; so if you shift the comb by less than half the distance between the teeth, you can measure the distance by which it’s been shifted. So you can encode information in these states and the noise in the lab can be measured and corrected.”
“Visionary theoretical discovery”
When the trio first published their results, Devoret says the paper received only limited attention. “I find this paper to be a wonderful example of a visionary theoretical discovery happening a little too early,” he says. “I remember reading this paper and thinking ‘Well this looks very clever but not very practical’.”
Since 2001, however, researchers have become more adept at creating exotic quantum states in various platforms. Moreover, they have realized that, as well as correcting for small displacements in position and momentum, GKP states can also compensate more effectively than any other states for the much more significant noise arising from photon loss from qubit states.
Last year, researchers at ETH Zurich in Switzerland created GKP states in qubits made of trapped ions, which are a leading contender for practical quantum computers. Now, Devoret and colleagues at Yale and the Inria Paris Research Centre have demonstrated quantum error correction of an encoded qubit in the other leading quantum-computing technology – qubits made from superconducting circuits.
Double the lifetime
The researchers initialized qubits in specific states and measured their lifetimes with and without applying the quantum error-correction algorithm. They found that the error-correction algorithm doubled the lifetime of all the quantum states to around 250 μs. “In our experiment we’re just protecting memory,” says Devoret, “The next step is to show fault-tolerant computation: you want to protect an operation and error correct while you are computing.”
Preskill is impressed. “Until now they’ve only demonstrated a fairly modest improvement over what they can do without using these special error-resistant states,” he says, “but it’s an important step.”
As John Martinis of University of California, Santa Barbara adds, “I think it’s a really interesting [achievement] and a step forward for the field because they made this error-protected logical qubit using ideas that have been around for a long time. They showed it worked.”
Martinis, who until recently worked at Google’s AI lab developing quantum computers, cautions however, that radical improvements may be necessary to compete with the brute force approach. “If you look at the technology of computers, we know that, over time, people learn how to make lots of bits – so we can make lots of qubits. The advantage here is that you do this error correction internally using one qubit with a complicated state, so you don’t necessarily have to scale up, but unless you extend the lifetime thousands or millions of times, how useful is it going to be?” he says.
The research is described in Nature.


physicsworld--2020-08-27--Molecular Trojan horse breaches blood–brain barrier - Physics World

Nanoparticles doped with molecules derived from a neurotransmitter can smuggle chemical cargoes across the blood–brain barrier ( BBB ) .
A team at Tufts University in the US created such nanoparticles and used them to deliver a diverse range of therapeutic substances into the brains of mice .
The technique could one day be used to treat neurological conditions such as infections and neurodegenerative disorders , while avoiding the side effects that accompany other methods for penetrating the BBB .
The BBB comprises a layer of endothelial cells that line the brain ’ s blood vessels .
This layer of @ @ @ @ @ @ @ brain from toxins and pathogens that might be circulating in the blood .
Unfortunately , it also keeps out most drugs and other therapeutics , making certain brain diseases difficult to treat by conventional methods of drug delivery .
Finding ways to breach or circumvent the BBB is a subject of active research .
Although some techniques have been shown to deliver drugs with a degree of success , methods that disrupt the barrier by chemical or physical means can simultaneously let other – potentially harmful –substances sneak across alongside the intended molecules @ @ @ @ @ @ @ Ma , Liu Yang and colleagues report an approach that is more selective .
To develop their technique , the team experimented with tryptamine , phenethylamine and phenylethanolamine , three chemicals that are naturally present in the brain .
These neurotransmitters are members of the special class of molecules that can cross the BBB , a process that is thought to occur via active transport ( rather than passive diffusion ) across the endothelial cells ’ membranes .
Ma , Yang and colleagues coupled the functional amines in the neurotransmitters to lipid chains @ @ @ @ @ @ @ ) that are hydrophobic at one end and hydrophilic at the other .
In an aqueous solution , such amphiphilic molecules bunch together to form spherical particles called micelles , which can encapsulate other chemical species within their cores .
By using NT–lipidoids in this process , the researchers created nanoparticles whose surfaces were studded with the neurotransmitter-derived amines .
When they injected NT–lipidoid nanoparticles carrying fluorescent dye into live mice , the researchers found that the tryptamine-derived formulation ( NT1 ) successfully breached the BBB and accumulated in the animals ’ brains @ @ @ @ @ @ @ surfaces of the nanoparticles apparently triggered the transport process that lets the neurotransmitter pass into and through endothelial cells .
A mystery that the researchers are currently investigating is why the phenethylamine and phenylethanolamine-derived formulations failed to achieve the same result .
To test the technique with a more therapeutically relevant cargo , next the team used NT1 nanoparticles to encapsulate amphotericin B , an antifungal drug to which the BBB is usually impermeable .
Like the fluorescent dye , this substance was also carried across the BBB successfully .
However , the @ @ @ @ @ @ @ the animals ’ brain tissue was even higher when they added lipidoids that included phenylboronic acid to the mixture .
This component makes the lipidoid more soluble in water , decreasing the size of the nanoparticles from 800 nm to 100 nm as a result .
For some treatments , merely getting the drug across the BBB is not enough , however .
Antisense therapy , for example , could be used to limit production of the tau-protein tangles associated with Alzheimer ’ s disease , but the antisense oligonucleotides ( ASOs ) @ @ @ @ @ @ @ into the neurons themselves .
To achieve this , the researchers incorporated into the nanoparticles yet another lipidoid , 306-O12B-3 , which they had previously shown could deliver ASOs into cells in the liver .
They found that nanoparticles that combined NT1 and 306-O12B-3 lipidoids transported the tau ASOs across both the BBB and the membranes of the neurons , yielding a reduction in tau mRNA .
Although the results are promising , the technique is still some way from the clinic .
“ More studies and clinical trials , including pharmacokinetics , @ @ @ @ @ @ @ needed to determine the utility and safety of the technology in humans , ” explains corresponding author Qiaobing Xu .
There are also still fundamental questions about the phenomenon at the heart of the work .
The ineffectiveness of lipidoids derived from phenethylamine and phenylethanolamine is unexplained , but even the way in which the tryptamine-doped nanoparticles work is unclear .
“ We think they cross the BBB by way of a transporter-mediated process , ” says Xu , “ but we don ’ t know the mechanism exactly .
”

In vivo delivery of a gene-editing protein (Cre-recombinase) into the mouse brain, visualized as red fluorescence (scale bar 100 μm). Inset: transmission electron microscopy image of lipid nanoparticles containing Cre-recombinase (scale bar 0.1 μm). (Courtesy: Qiaobing Xu, Tufts University)
Nanoparticles doped with molecules derived from a neurotransmitter can smuggle chemical cargoes across the blood–brain barrier (BBB). A team at Tufts University in the US created such nanoparticles and used them to deliver a diverse range of therapeutic substances into the brains of mice. The technique could one day be used to treat neurological conditions such as infections and neurodegenerative disorders, while avoiding the side effects that accompany other methods for penetrating the BBB.
The BBB comprises a layer of endothelial cells that line the brain’s blood vessels. This layer of cells is selectively permeable and protects the brain from toxins and pathogens that might be circulating in the blood. Unfortunately, it also keeps out most drugs and other therapeutics, making certain brain diseases difficult to treat by conventional methods of drug delivery.
Finding ways to breach or circumvent the BBB is the subject of active research. Although some techniques have been shown to deliver drugs with a degree of success, methods that disrupt the barrier by chemical or physical means can simultaneously let other – potentially harmful – substances sneak across alongside the intended molecules. Writing in Science Advances, Feihe Ma, Liu Yang and colleagues report an approach that is more selective.
Left to right: study authors Feihe Ma, Liu Yang and Qiaobing Xu. (Courtesy: Qiaobing Xu)
To develop their technique, the team experimented with three chemicals that are naturally present in the brain: tryptamine, phenethylamine and phenylethanolamine. These neurotransmitters are members of the special class of molecules that can cross the BBB in a process that is thought to occur via active transport (rather than passive diffusion) across the endothelial cells’ membranes.
Ma, Yang and colleagues coupled the functional amines in the neurotransmitters to lipid chains. This created composite molecules (NT–lipidoids) that are hydrophobic at one end and hydrophilic at the other. In an aqueous solution, such amphiphilic molecules bunch together to form spherical particles called micelles that can encapsulate other chemical species within their cores. By using NT–lipidoids in this process, the researchers created nanoparticles with surfaces studded with the neurotransmitter-derived amines.
When they injected NT–lipidoid nanoparticles carrying fluorescent dye into live mice, the researchers found that the tryptamine-derived formulation (NT1) successfully breached the BBB and accumulated in the animals’ brains. The presence of tryptamine on the surfaces of the nanoparticles apparently triggered the transport process that lets the neurotransmitter pass into and through endothelial cells. A mystery that the researchers are currently investigating is why the phenethylamine- and phenylethanolamine-derived formulations failed to achieve the same result.
To test the technique with a more therapeutically relevant cargo, next the team used NT1 nanoparticles to encapsulate amphotericin B, an antifungal drug to which the BBB is usually impermeable. Like the fluorescent dye, this substance was also carried across the BBB successfully. However, the researchers found that the concentration delivered to the animals’ brain tissue was even higher when they added lipidoids that included phenylboronic acid to the mixture. This component makes the lipidoid more soluble in water, thus decreasing the size of the nanoparticles from 800 nm to 100 nm as a result.
For some treatments, merely getting the drug across the BBB is not enough, however. Antisense therapy, for example, could be used to limit production of the tau-protein tangles associated with Alzheimer’s disease, but the antisense oligonucleotides (ASOs) that produce the beneficial effect must penetrate into the neurons themselves. To achieve this, the researchers incorporated into the nanoparticles yet another lipidoid, 306-O12B-3, which they had previously shown could deliver ASOs into cells in the liver. They found that nanoparticles that combined NT1 and 306-O12B-3 lipidoids transported the tau ASOs across both the BBB and the membranes of the neurons, yielding a reduction in tau mRNA.
Although the results are promising, the technique is still some way from the clinic. “More studies and clinical trials, including pharmacokinetics, pharmacodynamics, toxicity etc, will be needed to determine the utility and safety of the technology in humans,” explains corresponding author Qiaobing Xu.
There are also still fundamental questions about the phenomenon at the heart of the work. The ineffectiveness of lipidoids derived from phenethylamine and phenylethanolamine is unexplained, but even the way in which the tryptamine-doped nanoparticles work is unclear. “We think they cross the BBB by way of a transporter-mediated process,” says Xu, “but we don’t know the mechanism exactly.”


physicsworld--2020-08-27--Particle and atomic physics more likely to win Nobels - Physics World

Research into particle and atomic physics is more likely to be awarded a Nobel prize than work in other fields .
That is according to a new analysis from scientists at Stanford University , who find , however , that research that does achieve such recognition may actually have far less impact than other discoveries made at the same time .
John Ioannidis and colleagues from Stanford mapped the key Nobel-prize-related publication of each laureate who was awarded a prize in either physics , chemistry or physiology and medicine between 1995 and 2017 .
They also analysed 63 million other @ @ @ @ @ @ @ published in the same timeframe .
The work revealed that , out of 114 scientific fields , particle and atomic physics alone account for a quarter of Nobel prizes awarded during the period covered by the study .
When including cell biology , neuroscience and molecular chemistry , these five fields accounted for more than half of awards .
Furthermore , almost all Nobel-prize-related papers have been cited less extensively than top papers published around the same time .
While the authors are unable to determine whether this clustering is driven by the @ @ @ @ @ @ @ of the awardees , or both , they are concerned that it might create a culture where some scientists are considered less worthy simply because of the field in which they work .
It might even influence the fields in which researchers choose to undertake research .
“ Scientists do care about rewards and incentives .
Therefore , they may be attracted to work in fields or subdisciplines that are attracting more recognition , funding , and have better odds of being seen as important science , ” Ioannidis told Physics World .
@ @ @ @ @ @ @ approaches is a strength of science , and too much clustering of recognition may be detrimental in this regard.
” Lutz Bornmann , a science sociologist at the headquarters of the Max Planck Society in Munich , is “ surprised ” by the team ’ s findings .
“ I had expected that the Nobel prizes are more evenly distributed across fields , ” he says .
He wonders whether , in addition to the potential for bias in the nomination and selection processes , the clustering might indicate that certain fields of @ @ @ @ @ @ @ of ground-breaking research likely to achieve Nobel recognition .
Bornmann is keen , however , for scientists to continue their research efforts in whichever field captures their interest .
“ Although the study revealed these clustering processes , researchers should not adjust their careers to the results of the study , ” he says .
After all , he explains , even researchers active in fields seemingly favoured by the prize stand only a very small chance of being awarded a Nobel , however worthy their achievements .
“ Many candidates deserve a @ @ @ @ @ @ @ but only a few receive it.
” The research is published in PLOS One .

Topic of choice: a bibliometric analysis has found that certain fields are more likely to garner a Nobel prize than others. (Courtesy: Nobel Foundation)
Research into particle and atomic physics is more likely to be awarded a Nobel prize than work in other fields. That is according to new analysis from scientists at Stanford University, who find, however, that research that does achieve such recognition may actually have far less impact than other discoveries made at the same time.
John Ioannidis and colleagues from Stanford mapped the key Nobel-prize-related publication of each laureate who was awarded a prize in either physics, chemistry or physiology and medicine between 1995 and 2017. They also analysed 63 million other articles from the Scopus database that were published in the same timeframe. The work revealed that, out of 114 scientific fields, particle and atomic physics alone account for a quarter of Nobel prizes awarded during the period covered by the study. When including cell biology, neuroscience and molecular chemistry, these five fields accounted for more than half of the awards. Furthermore, almost all Nobel-prize-related papers have been cited less extensively than top papers published around the same time.
Many candidates deserve a prize, but only a few receive it Lutz Bornmann
While the Stanford group was unable to determine whether this clustering is driven by the nomination of candidates or by the selection of the awardees, or both, they are concerned that it might create a culture where some scientists are considered less worthy simply because of the field in which they work. It might even influence the fields in which researchers choose to undertake research. “Scientists do care about rewards and incentives. Therefore, they may be attracted to work in fields or subdisciplines that are attracting more recognition, funding and have better odds of being seen as important science,” Ioannidis told Physics World. “Diversity and richness of disciplines and approaches is a strength of science, and too much clustering of recognition may be detrimental in this regard.”
Ground-breaking research
Lutz Bornmann, a science sociologist at the headquarters of the Max Planck Society in Munich, Germany, is “surprised” by the team’s findings. “I had expected that the Nobel prizes would be evenly distributed across fields,” he says. He wonders whether, in addition to the potential for bias in the nomination and selection processes, the clustering might indicate that certain fields of science are more amenable to the type of ground-breaking research likely to achieve Nobel recognition.
Bornmann is keen, however, for scientists to continue their research efforts in whichever field captures their interest. “Although the study revealed these clustering processes, researchers should not adjust their careers to the results of the study,” he says. After all, he explains, even researchers active in fields seemingly favoured by the prize stand only a very small chance of being awarded a Nobel, however worthy their achievements. “Many candidates deserve a prize,” he says, “but only a few receive it.”
The research is published in PLOS One.


physicsworld--2020-08-26--Autonomous cars: potential lifesavers but with new risks - Physics World

Studies suggest that human error is responsible for over 90 % of the 1.25 million people who die each year globally due to car accidents .
Therefore , improving driver safety is one of the biggest incentives for increasing the autonomy of vehicles .
But this brave new world of autonomous driving is not without its own risks – as Andrew Glester discovers in the August episode of the Physics World Stories podcast .
To learn about how automated features can reduce human error , Glester catches up with Siddartha Khastgir , the head of Verification & Validation of Connected @ @ @ @ @ @ @ of Warwick , UK .
Khastgir describes the form that fully automated vehicles might take , and explains why it is a myth that these vehicles could provide absolute safety without human intervention .
Cars today already have a degree of autonomy , such as parking-assist systems that use ultrasonic sensors .
This autonomy is increasing every year , as sensors and other hardware can monitor a car ’ s state and create dynamic maps of its surroundings .
But these systems bring a new threat – opportunities for hackers to access cars @ @ @ @ @ @ @ risks , Glester speaks with Simon Parkinson , a computer scientist who leads the Centre for Cyber Security at the University of Huddersfield , UK .
Find out more about the cyber threat posed to autonomous vehicles in this feature by Stephen Ornes , originally published in the August edition of Physics World , a special issue on the physics of cars .

Studies suggest that human error is responsible for over 90% of the 1.25 million people who die each year globally due to car accidents. Therefore, improving driver safety is one of the biggest incentives for increasing the autonomy of vehicles. But this brave new world of autonomous driving is not without its own risks – as Andrew Glester discovers in the August episode of the Physics World Stories podcast.
To learn about how automated features can reduce human error, Glester catches up with Siddartha Khastgir, the head of Verification & Validation of Connected and Autonomous Vehicles at WMG, University of Warwick, UK. Khastgir describes the form that fully automated vehicles might take, and explains why it is a myth that these vehicles could provide absolute safety without human intervention.
Cars today already have a degree of autonomy, such as parking-assist systems that use ultrasonic sensors. This autonomy is increasing every year, as sensors and other hardware can monitor a car’s state and create dynamic maps of its surroundings. But these systems bring a new threat – opportunities for hackers to access cars remotely. To learn about these emerging risks, Glester speaks with Simon Parkinson, a computer scientist who leads the Centre for Cyber Security at the University of Huddersfield, UK.
Find out more about the cyber threat posed to autonomous vehicles in this feature by Stephen Ornes, originally published in the August edition of Physics World, a special issue on the physics of cars.


physicsworld--2020-08-26--‘Reluctant’ metals make a new state of matter - Physics World

The first robust computational model of so-called “ strange ” metals has revealed that they are in fact a new state of matter .
The model , developed by physicists from Cornell University and the Flatiron Institute , both in New York , could advance our understanding of other correlated quantum materials , such as high-temperature superconductors and even black holes .
Strange metals get their name from the peculiar behaviour of their electrons .
Unlike electrons in ordinary metals , which travel freely with few interactions and little resistance , electrons in strange metals move sluggishly and in a @ @ @ @ @ @ @ at the fastest possible rate allowed by the fundamental laws of quantum mechanics .
In this sense , strange metals lie somewhere between metals and insulators , which have strongly-interacting electrons that occupy fixed positions .
But their strangeness doesn ’ t end there .
For more than 30 years , researchers have puzzled over the fact that strange metals can become superconductors when cooled below a certain ( relatively high ) critical temperature .
While models of this behaviour have existed for a while , they could not be accurately solved because @ @ @ @ @ @ @ they can not be treated as individual particles .
What is more , any real material will have an enormous number of electrons , making exact solutions impossible .
Transition between an ordinary metal and an insulator A team of researchers led by Eun-Ah Kim of Cornell ’ s Department of Physics have now solved this problem using a combination of two methods .
First , they used a “ quantum embedding ” technique based on an approach developed in the 1990s by team member Antoine Georges of The Flatiron Institute ’ s @ @ @ @ @ @ @ ) .
Here , the researchers performed detailed calculations on a few atoms in the system , rather than on the whole quantum system .
They then used a quantum Monte Carlo algorithm , which relies on random sampling of the atoms , to solve the model of strange metals down to absolute zero .
A key feature of the resulting model , Kim explains , is that when the electrons ’ kinetic energy is low , and their position therefore becomes more fixed , the system enters a so-called spin glass insulator @ @ @ @ @ @ @ interactions between electron spins do not allow individual spins to point in the same direction as the spins of their neighbours , leading to “ frustration ” and a random alignment of spins .
Conversely , when kinetic energy is high , the electrons move freely , and the system enters a weakly-interacting state known as a Fermi liquid .
In this state , large numbers of electrons can be modelled as non-interacting quasiparticles , each with an effective mass that exceeds that of a free electron .
The Fermi-liquid model is good @ @ @ @ @ @ @ – including the fact that , at low temperatures , the resistance of a conventional metal scales with the square of its temperature .
Kim points out that this scaling does not apply to strange metals .
Instead , their electrical conductivity depends linearly on temperature , with the Planck and Boltzmann constants appearing as scaling factors .
For this reason , strange metals are sometimes known as non-Fermi liquids or , alternatively , as Planckian metals .
By adjusting the ratio between the kinetic energy and interaction energy of the electrons in @ @ @ @ @ @ @ to drive their model system to the verge of a transition between an ordinary metal and an interaction-driven insulator .
At this point , strange metals appeared as a new state of matter , bordering these two known phases .
“ We found there is a whole region in the phase space that is exhibiting Planckian behaviour rather than belonging to either of the two phases that we ’ re transitioning between , ” Kim says .
In this quantum spin liquid state , the electrons are not completely locked down , but @ @ @ @ @ @ @ , she adds – making the material metallic , but only “ reluctantly ” so .
The new result , detailed in PNAS , could shed fresh light on the physics of high-temperature superconductors , which are related to Planckian metals in that their electrical resistance does not vary as expected with temperature either .
More surprisingly , it could also have links to astrophysics .
Like strange metals , black holes have properties ( such as the length of time a black hole “ resonates ” after merging with another black hole @ @ @ @ @ @ @ the Planck and Boltzmann constants .
“ The fact that you find this same scaling across all these different systems is fascinating , ” adds team member Olivier Parcollet of the CCQ .

Strange metals emerge in a regime separating a metallic spin glass and a Fermi liquid. Credit: P. Cha et al./Proceedings of the National Academy of Sciences 2020
The first robust computational model of so-called “strange” metals has revealed that they are in fact a new state of matter. The model, developed by physicists from Cornell University and the Flatiron Institute, both in New York, could advance our understanding of other correlated quantum materials, such as high-temperature superconductors and even black holes.
Strange metals get their name from the peculiar behaviour of their electrons. Unlike electrons in ordinary metals, which travel freely with few interactions and little resistance, electrons in strange metals move sluggishly and in a restricted fashion. They also dissipate energy at the fastest possible rate allowed by the fundamental laws of quantum mechanics. In this sense, strange metals lie somewhere between metals and insulators, which have strongly-interacting electrons that occupy fixed positions.
But their strangeness doesn’t end there. For more than 30 years, researchers have puzzled over the fact that strange metals can become superconductors when cooled below a certain (relatively high) critical temperature. While models of this behaviour have existed for a while, they could not be accurately solved because the electrons are entangled, meaning that they cannot be treated as individual particles. What is more, any real material will have an enormous number of electrons, making exact solutions impossible.
Transition between an ordinary metal and an insulator
A team of researchers led by Eun-Ah Kim of Cornell’s Department of Physics have now solved this problem using a combination of two methods. First, they used a “quantum embedding” technique based on an approach developed in the 1990s by team member Antoine Georges of The Flatiron Institute’s Center for Computational Quantum Physics (CCQ). Here, the researchers performed detailed calculations on a few atoms in the system, rather than on the whole quantum system. They then used a quantum Monte Carlo algorithm, which relies on random sampling of the atoms, to solve the model of strange metals down to absolute zero.
A key feature of the resulting model, Kim explains, is that when the electrons’ kinetic energy is low, and their position therefore becomes more fixed, the system enters a so-called spin glass insulator state. In this state, random interactions between electron spins do not allow individual spins to point in the same direction as the spins of their neighbours, leading to “frustration” and a random alignment of spins.
Conversely, when kinetic energy is high, the electrons move freely, and the system enters a weakly-interacting state known as a Fermi liquid. In this state, large numbers of electrons can be modelled as non-interacting quasiparticles, each with an effective mass that exceeds that of a free electron. The Fermi-liquid model is good at predicting the properties of conventional metals – including the fact that, at low temperatures, the resistance of a conventional metal scales with the square of its temperature.
Kim points out that this scaling does not apply to strange metals. Instead, their electrical conductivity depends linearly on temperature, with the Planck and Boltzmann constants appearing as scaling factors. For this reason, strange metals are sometimes known as non-Fermi liquids or, alternatively, as Planckian metals.
A “reluctant” metal
By adjusting the ratio between the kinetic energy and interaction energy of the electrons in their model, the researchers were able to drive their model system to the verge of a transition between an ordinary metal and an interaction-driven insulator. At this point, strange metals appeared as a new state of matter, bordering these two known phases.
“We found there is a whole region in the phase space that is exhibiting Planckian behaviour rather than belonging to either of the two phases that we’re transitioning between,” Kim says. In this quantum spin liquid state, the electrons are not completely locked down, but they are also not completely free either, she adds – making the material metallic, but only “reluctantly” so.
The new result, detailed in PNAS, could shed fresh light on the physics of high-temperature superconductors, which are related to Planckian metals in that their electrical resistance does not vary as expected with temperature either. More surprisingly, it could also have links to astrophysics. Like strange metals, black holes have properties (such as the length of time a black hole “resonates” after merging with another black hole) that depend only on temperature and the Planck and Boltzmann constants. “The fact that you find this same scaling across all these different systems is fascinating,” adds team member Olivier Parcollet of the CCQ.