Tag Archives: ICL

Paving the way for hardware neural networks?

I’m glad the Imperial College of London (ICL; UK) translated this research into something I can, more or less, understand because the research team’s title for their paper would have left me ‘confuzzled’ .Thank you for this November 20, 2017 ICL press release (also on EurekAlert) by Hayley Dunning,

Researchers have shown how to write any magnetic pattern desired onto nanowires, which could help computers mimic how the brain processes information.

Much current computer hardware, such as hard drives, use magnetic memory devices. These rely on magnetic states – the direction microscopic magnets are pointing – to encode and read information.

Exotic magnetic states – such as a point where three south poles meet – represent complex systems. These may act in a similar way to many complex systems found in nature, such as the way our brains process information.

Computing systems that are designed to process information in similar ways to our brains are known as ‘neural networks’. There are already powerful software-based neural networks – for example one recently beat the human champion at the game ‘Go’ – but their efficiency is limited as they run on conventional computer hardware.

Now, researchers from Imperial College London have devised a method for writing magnetic information in any pattern desired, using a very small magnetic probe called a magnetic force microscope.

With this new writing method, arrays of magnetic nanowires may be able to function as hardware neural networks – potentially more powerful and efficient than software-based approaches.

The team, from the Departments of Physics and Materials at Imperial, demonstrated their system by writing patterns that have never been seen before. They published their results today [November 20, 2017] in Nature Nanotechnology.

Interlocking hexagon patterns with complex magnetisation

‘Hexagonal artificial spin ice ground state’ – a pattern never demonstrated before. Coloured arrows show north or south polarisation

Dr Jack Gartside, first author from the Department of Physics, said: “With this new writing method, we open up research into ‘training’ these magnetic nanowires to solve useful problems. If successful, this will bring hardware neural networks a step closer to reality.”

As well as applications in computing, the method could be used to study fundamental aspects of complex systems, by creating magnetic states that are far from optimal (such as three south poles together) and seeing how the system responds.

Here’s a link to and a citation for the paper,

Realization of ground state in artificial kagome spin ice via topological defect-driven magnetic writing by Jack C. Gartside, Daan M. Arroo, David M. Burn, Victoria L. Bemmer, Andy Moskalenko, Lesley F. Cohen & Will R. Branford. Nature Nanotechnology (2017) doi:10.1038/s41565-017-0002-1 Published online: 20 November 2017

This paper is behind a paywall.

*Odd spacing eliminated and a properly embedded video added on February 6, 2018 at 18:16 hours PT.

Seeing quantum objects with the naked eye

This research is a collaborative effort between the Polytechnique de Montréal (or École polytechnique de Montréal; Canada) and the Imperial College of London (UK) according to a July 14, 2015 news item on Nanotechnology Now,

For the first time, the wavelike behaviour of a room-temperature polariton condensate has been demonstrated in the laboratory on a macroscopic length scale. This significant development in the understanding and manipulation of quantum objects is the outcome of a collaboration between Professor Stéphane Kéna-Cohen of Polytechnique Montréal, Professor Stefan Maier and research associate Konstantinos Daskalakis of Imperial College London. …

A July 14, 2015 Polytechnique de Montréal news release supplies an explanation of this ‘sciencish’ accomplishment,

Quantum objects visible to the naked eye

Quantum mechanics tells us that objects exhibit not only particle-like behaviour, but also wavelike behaviour with a wavelength inversely proportional to the object’s velocity. Normally, this behaviour can only be observed at atomic length scales. There is one important exception, however: with bosons, particles of a particular type that can be combined in large numbers in the same quantum state, it is possible to form macroscopic-scale quantum objects, called Bose-Einstein condensates.

These are at the root of some of quantum physics’ most fascinating phenomena, such as superfluidity and superconductivity. Their scientific importance is so great that their creation, nearly 70 years after their existence was theorized, earned researchers Eric Cornell, Wolfgang Ketterle and Carl Wieman the Nobel Prize in Physics in 2001.

A trap for half-light, half-matter quasi-particles

Placing particles in the same state to obtain a condensate normally requires the temperature to be lowered to a level near absolute zero: conditions achievable only with complex laboratory techniques and expensive cryogenic equipment.

“Unlike work carried out to date, which has mainly used ultracold atomic gases, our research allows comprehensive studies of condensation to be performed in condensed matter systems under ambient conditions” explains Mr. Daskalakis. He notes that this is a key step toward carrying out physics projects that currently remain purely theoretical.

To produce the room-temperature condensate, the team of researchers from Polytechnique and Imperial College first created a device that makes it possible for polaritons – hybrid quasi-particles that are part light and part matter – to exist. The device is composed of a film of organic molecules 100 nanometres thick, confined between two nearly perfect mirrors. The condensate is created by first exciting a sufficient number of polaritons using a laser and then observed via the blue light it emits. Its dimensions can be comparable to that of a human hair, a gigantic size on the quantum scale.

“To date, the majority of polariton experiments continue to use ultra-pure crystalline semiconductors,” says Professor Kéna-Cohen. “Our work demonstrates that it is possible to obtain comparable quantum behaviour using ‘impure’ and disordered materials such as organic molecules. This has the advantage of allowing for much simpler and lower-cost fabrication.”

The size of the condensate is a limiting factor

In addition to directly observing the organic polariton condensate’s wavelike behaviour, the experiment showed researchers that ultimately the condensate size could not exceed approximately 100 micrometres. Beyond this limit, the condensate begins to destroy itself, fragmenting and creating vortices.

Toward future polariton lasers and optical transistors

In a condensate, the polaritons all behave the same way, like photons in a laser. The study of room-temperature condensates paves the way for future technological breakthroughs such as polariton micro-lasers using low-cost organic materials, which are more efficient and require less activation power than  conventional lasers. Powerful transistors entirely powered by light are another possible application.

The research team foresees that the next major challenge in developing such applications will be to obtain a lower particle-condensation threshold so that the external laser used for pumping could be replaced by more practical electrical pumping.

Fertile ground for studying fundamental questions

According to Professor Maier, this research is also creating a platform to facilitate the study of fundamental questions in quantum mechanics. “It is linked to many modern and fascinating aspects of many-body physics, such as Bose-Einstein condensation and superfluidity, topics that also intrigue the general public,” he notes.

Professor Kéna-Cohen concludes: “One fascinating aspect, for example, is the extraordinary transition between the state of non-condensed particles and the formation of a condensate. On a small scale, the physics of this transition resemble an important step in the formation of the Universe after the Big Bang.”

Here’s a link to and a citation for the paper,

Spatial Coherence and Stability in a Disordered Organic Polariton Condensate by K. S. Daskalakis, S. A. Maier, and S. Kéna-Cohen Phys. Rev. Lett. 115 (3), 035301 DOI: 10.1103/PhysRevLett.115.035301 Published 13 July 2015

This article is behind a paywall but there is an earlier open access version  here: http://arxiv.org/pdf/1503.01373v2.

Treating municipal wastewater and dirty industry byproducts with nanocellulose-based filters

Researchers at Sweden’s Luleå University of Technology have created nanocellulose-based filters in collaboration with researchers at the Imperial College of London (ICL) good enough for use as filters according to a Dec. 23, 2014 news item on Nanowerk,

Prototypes of nano-cellulose based filters with high purification capacity towards environmentally hazardous contaminants from industrial effluents e.g. process industries, have been developed by researchers at Luleå University of Technology. The research, conducted in collaboration with Imperial College in the UK has reached a breakthrough with the prototypes and they will now be tested on a few industries in Europe.

“The bio-based filter of nano-cellulose is to be used for the first time in real-life situations and tested within a process industry and in municipal wastewater treatment in Spain. Other industries have also shown interest in this technology and representatives of the mining industry have contacted me and I have even received requests from a large retail chain in the UK,” says Aji Mathew Associate Professor, Division of Materials Science at Luleå University.

A Dec. 22, 2014 Luleå University of Technology press release, which originated the news item, further describes the research,

Researchers have combined a cheap residue from the cellulose industry, with functional nano-cellulose to prepare adsorbent sheets with high filtration capacity. The sheets have since been constructed to different prototypes, called cartridges, to be tested. They have high capacity and can filter out heavy metal ions from industrial waters, dyes residues from the printing industry and nitrates from municipal water. Next year, larger sheets with a layer of nano-cellulose can be produced and formed into cartridges, with higher capacity.

– Each such membrane can be tailored to have different removal capability depending on the kind of pollutant, viz., copper, iron, silver, dyes, nitrates and the like, she says.

Behind the research, which is funded mainly by the EU, is a consortium of research institutes, universities, small businesses and process industries. It is coordinated by Luleå University led by Aji Mathew. She thinks that the next step is to seek more money from the EU to scale up this technology to industrial level.

– Alfa Laval is very interested in this and in the beginning of 2015, I go in with a second application to the EU framework program Horizon 2020 with goals for full-scale demonstrations of this technology, she says.

Two of Aji Mathews graduate student Peng Liu and Zoheb Karim is also deeply involved in research on nano-filters.

– I focus on how these membranes can filter out heavy metals by measuring different materials such as nanocrystals and nano-fibers to determine their capacity to absorb and my colleague focuses on how to produce membranes, says Peng Liu PhD student in the Department of Materials Science and Engineering at Luleå University of Technology.

I have been following the nanocellulose work at Luleå University of Technology for a few years now. The first piece was a Feb. 15, 2012 post titled, The Swedes, sludge, and nanocellulose fibres, and the next was a Sept. 19, 2013 post titled, Nanocellulose and forest residues at Luleå University of Technology (Sweden). It’s nice to mark the progress over time although I am curious as to the source for the nanocellulose, trees, carrots, bananas?

The evolution of molecules as observed with femtosecond stimulated Raman spectroscopy

A July 3, 2014 news item on Azonano features some recent research from the Université de Montréal (amongst other institutions),

Scientists don’t fully understand how ‘plastic’ solar panels work, which complicates the improvement of their cost efficiency, thereby blocking the wider use of the technology. However, researchers at the University of Montreal, the Science and Technology Facilities Council, Imperial College London and the University of Cyprus have determined how light beams excite the chemicals in solar panels, enabling them to produce charge.

A July 2, 2014 University of Montreal news release, which originated the news item, provides a fascinating description of the ultrafast laser process used to make the observations,

 “We used femtosecond stimulated Raman spectroscopy,” explained Tony Parker of the Science and Technology Facilities Council’s Central Laser Facility. “Femtosecond stimulated Raman spectroscopy is an advanced ultrafast laser technique that provides details on how chemical bonds change during extremely fast chemical reactions. The laser provides information on the vibration of the molecules as they interact with the pulses of laser light.” Extremely complicated calculations on these vibrations enabled the scientists to ascertain how the molecules were evolving. Firstly, they found that after the electron moves away from the positive centre, the rapid molecular rearrangement must be prompt and resemble the final products within around 300 femtoseconds (0.0000000000003 s). A femtosecond is a quadrillionth of a second – a femtosecond is to a second as a second is to 3.7 million years. This promptness and speed enhances and helps maintain charge separation.  Secondly, the researchers noted that any ongoing relaxation and molecular reorganisation processes following this initial charge separation, as visualised using the FSRS method, should be extremely small.

As for why the researchers’ curiosity was stimulated (from the news release),

The researchers have been investigating the fundamental beginnings of the reactions that take place that underpin solar energy conversion devices, studying the new brand of photovoltaic diodes that are based on blends of polymeric semiconductors and fullerene derivatives. Polymers are large molecules made up of many smaller molecules of the same kind – consisting of so-called ‘organic’ building blocks because they are composed of atoms that also compose molecules for life (carbon, nitrogen, sulphur). A fullerene is a molecule in the shape of a football, made of carbon. “In these and other devices, the absorption of light fuels the formation of an electron and a positive charged species. To ultimately provide electricity, these two attractive species must separate and the electron must move away. If the electron is not able to move away fast enough then the positive and negative charges simple recombine and effectively nothing changes. The overall efficiency of solar devices compares how much recombines and how much separates,” explained Sophia Hayes of the University of Cyprus, last author of the study.

… “Our findings open avenues for future research into understanding the differences between material systems that actually produce efficient solar cells and systems that should as efficient but in fact do not perform as well. A greater understanding of what works and what doesn’t will obviously enable better solar panels to be designed in the future,” said the University of Montreal’s Carlos Silva, who was senior author of the study.

Here’s a link to and a citation for the paper,

Direct observation of ultrafast long-range charge separation at polymer–fullerene heterojunctions by Françoise Provencher, Nicolas Bérubé, Anthony W. Parker, Gregory M. Greetham, Michael Towrie, Christoph Hellmann, Michel Côté, Natalie Stingelin, Carlos Silva & Sophia C. Hayes. Nature Communications 5, Article number: 4288 doi:10.1038/ncomms5288 Published 01 July 2014

This article is behind a paywall but there is a free preview available vie ReadCube Access.

Putting a new spin on it: Whirling Dervishes and physics and ballet dancers and neuroscience

Many years ago I was dragged to a movie about J. Krishnamurti (a philosopher and spiritual teacher; there’s more in this Wikipedia essay) which, for some reason, featured Whirling Dervishes amongst many other topics. Watching those dervishes was hypnotic and I now find out it was also an experience in physics, according to a Nov. 26, 2013 news item on ScienceDaily,

A force that intricately links the rotation of the Earth with the direction of weather patterns in the atmosphere has been shown to play a crucial role in the creation of the hypnotic patterns created by the skirts of the Whirling Dervishes.

This is according to an international group of researchers who have demonstrated how the Coriolis force is essential for creating the archetypal, and sometimes counterintuitive, patterns that form on the surface of the Whirling Dervishes skirts by creating a set of very simple equations which govern how fixed or free-flowing cone-shaped structures behave when rotating.

The Nov. 26, 2013 Institute of Physics (IOP) news release on EurekAlert (also on the IOP website but dated Nov. 27, 2013), which originated the news item, gives an explanation of Whirling Dervishes and describes the research further,

The Whirling Dervishes, who have become a popular tourist attraction in Turkey, are a religious movement who commemorate the 13th-century Persian poet, Rumi, by spinning on the spot and creating mesmerising patterns with their long skirts. A YouTube video of the Whirling Dervishes in action can be viewed here: https://www.youtube.com/watch?v=L_Cf-ZxDfZA.

Co-author of the study James Hanna, from Virginia Polytechnic Institute and State University, said: “The dancers don’t do much but spin around at a fixed speed, but their skirts show these very striking, long-lived patterns with sharp cusp-like features which seem rather counterintuitive.”

Hanna, along with Jemal Guven at the Universidad Nacional Autónoma de México and Martin Michael Müller at Université de Lorraine, found that it was the presence of a Coriolis force that was essential in the formation of the different patterns.

The Coriolis effect accounts for the deflection of objects on a rotating surface and is most commonly encountered when looking at the Earth’s rotations and its effect on the atmosphere around it. The rotation of the Earth creates the Coriolis force which causes winds to be deflected clockwise in the Northern Hemisphere and anti-clockwise in the Southern Hemisphere – it is this effect which is responsible for the rotation of cyclones.

“Because the sheet is conically symmetric, material can flow along its surface without stretching or deforming. You can think of the rotating Earth, for example, with the air of the atmosphere free to flow around it.

“The flow of a sheet of material is much more restrictive than the flow of the atmosphere, but nonetheless it results in Coriolis forces. What we found was that this flow, and the associated Coriolis forces, plays a crucial role in forming the dervish-like patterns,” Hanna continued.

By providing a basic mathematical description of the spinning skirts of the Dervishes, the researchers hope their future research will discern how different patterns are selected, how stable these patterns are and if gravity or any other effects make a qualitative difference.

The news release notes,

The equations, which have been published today, 27 November,[2013], in the Institute of Physics and German Physical Society’s New Journal of Physics, were able to reproduce the sharp peaks and gentle troughs that appear along the flowing surface of the Dervishes’ skirts and showed a significant resemblance to real-life images.

Here’s a link to and a citation for the paper,

Whirling skirts and rotating cones by Jemal Guven, J A Hanna, and Martin Michael Müller. New Journal of Physics Volume 15 November 2013 doi:10.1088/1367-2630/15/11/113055  Published 26 November 2013

© IOP Publishing and Deutsche Physikalische Gesellschaft

This paper is open access.

While the Whirling Dervishes and the fabric in their clothing provide insights into aspects of physics, ballet dancers are providing valuable information to neuroscientists and geriatric specialists with pirouettes, according to a Sept. 26, 2013 news item on ScienceDaily,

Scientists have discovered differences in the brain structure of ballet dancers that may help them avoid feeling dizzy when they perform pirouettes.

The research suggests that years of training can enable dancers to suppress signals from the balance organs in the inner ear.

The findings, published in the journal Cerebral Cortex, could help to improve treatment for patients with chronic dizziness. Around one in four people experience this condition at some time in their lives.

The Imperial College of London (ICL) Sept. 26, 2013 news release on EurekAlert (also on the ICL website but dated Sept. 27, 2013), which originated the news item, describes dizziness, this research, and ballet dancers’ unique brains in more detail,

Normally, the feeling of dizziness stems from the vestibular organs in the inner ear. These fluid-filled chambers sense rotation of the head through tiny hairs that sense the fluid moving. After turning around rapidly, the fluid continues to move, which can make you feel like you’re still spinning.

Ballet dancers can perform multiple pirouettes with little or no feeling of dizziness. The findings show that this feat isn’t just down to spotting, a technique dancers use that involves rapidly moving the head to fix their gaze on the same spot as much as possible.

Researchers at Imperial College London recruited 29 female ballet dancers and, as a comparison group, 20 female rowers whose age and fitness levels matched the dancers’.

The volunteers were spun around in a chair in a dark room. They were asked to turn a handle in time with how quickly they felt like they were still spinning after they had stopped. The researchers also measured eye reflexes triggered by input from the vestibular organs. Later, they examined the participants’ brain structure with MRI scans.

In dancers, both the eye reflexes and their perception of spinning lasted a shorter time than in the rowers.

Dr Barry Seemungal, from the Department of Medicine at Imperial, said: “Dizziness, which is the feeling that we are moving when in fact we are still, is a common problem. I see a lot of patients who have suffered from dizziness for a long time. Ballet dancers seem to be able to train themselves not to get dizzy, so we wondered whether we could use the same principles to help our patients.”

The brain scans revealed differences between the groups in two parts of the brain: an area in the cerebellum where sensory input from the vestibular organs is processed and in the cerebral cortex, which is responsible for the perception of dizziness.

The area in the cerebellum was smaller in dancers. Dr Seemungal thinks this is because dancers would be better off not using their vestibular systems, relying instead on highly co-ordinated pre-programmed movements.

“It’s not useful for a ballet dancer to feel dizzy or off balance. Their brains adapt over years of training to suppress that input. Consequently, the signal going to the brain areas responsible for perception of dizziness in the cerebral cortex is reduced, making dancers resistant to feeling dizzy. If we can target that same brain area or monitor it in patients with chronic dizziness, we can begin to understand how to treat them better.”

Another finding in the study may be important for how chronic dizzy patients are tested in the clinic. In the control group, the perception of spinning closely matched the eye reflexes triggered by vestibular signals, but in dancers, the two were uncoupled.

“This shows that the sensation of spinning is separate from the reflexes that make your eyes move back and forth,” Dr Seemungal said. “In many clinics, it’s common to only measure the reflexes, meaning that when these tests come back normal the patient is told that there is nothing wrong. But that’s only half the story. You need to look at tests that assess both reflex and sensation.”

For the curious, here’s a link to and a citation for the paper,

The Neuroanatomical Correlates of Training-Related Perceptuo-Reflex Uncoupling in Dancers by Yuliya Nigmatullina, Peter J. Hellyer, Parashkev Nachev, David J. Sharp, and Barry M. Seemungal. Cereb. Cortex (2013) doi: 10.1093/cercor/bht266 First published online: September 26, 2013

Delightfully, this article too is open access.

I love these kinds of stories where two very different branches of science find information of interest in something as ordinary as spinning around.

Courtesy: Imperial College of London (downloaded from: http://www3.imperial.ac.uk/newsandeventspggrp/imperialcollege/newssummary/news_26-9-2013-17-43-4]

Courtesy: Imperial College of London (downloaded from: http://www3.imperial.ac.uk/newsandeventspggrp/imperialcollege/newssummary/news_26-9-2013-17-43-4]

Here are some Whirling Dervishes,

Istanbul - Monestir Mevlevi - Dervixos dansaires Credit: Josep Renalias [downloaded from: http://en.wikipedia.org/wiki/File:Istanbul_-_Monestir_Mevlevi_-_Dervixos_dansaires.JPG]

Istanbul – Monestir Mevlevi – Dervixos dansaires Credit: Josep Renalias [downloaded from: http://en.wikipedia.org/wiki/File:Istanbul_-_Monestir_Mevlevi_-_Dervixos_dansaires.JPG]

ETA Nov. 28, 2013: I was most diverted by the Nov. 27, 2013 Virginia Tech news release (also on EurekAlert) which describes how two physicists and an engineer came to study Whirling Dervishes,

James Hanna likes to have fun with his engineering views of physics.

So when he and his colleague Jemal Guven visited their friend Martin Michael Müller in France on a rainy, dreary day, the three intellects decided to stay in. Guven, absent-mindedly switching between channels on the television, stumbled upon a documentary on whirling dervishes, best described as a Sufi religious order, who commemorate the teachings of 13th century Persian mystic and poet Rumi through spinning at a fixed speed in their floor length skirts.

“Their skirts showed these very striking, long-lived patterns,” Hanna, the engineer, recalled.

The film caused physicists Guven and Müller to think about structures with conical symmetry, or those shapes that can be defined as a series of straight lines emanating from a single point. By contrast, Hanna, the engineer with a physicist’s background, thought about rotating flexible structures, namely strings or sheets.

Pop and rock music lead to better solar cells

A Nov. 6, 2013 news item on Nanowerk reveals that scientists at the Imperial College of London (UK) and Queen Mary University of London (UK),

Playing pop and rock music improves the performance of solar cells, according to new research from scientists at Queen Mary University of London and Imperial College London.

The high frequencies and pitch found in pop and rock music cause vibrations that enhanced energy generation in solar cells containing a cluster of ‘nanorods’, leading to a 40 per cent increase in efficiency of the solar cells.

The study has implications for improving energy generation from sunlight, particularly for the development of new, lower cost, printed solar cells.

The Nov. 6, 2013 Imperial College of London (ICL) news release, which originated the news item, gives more details about the research,

The researchers grew billions of tiny rods (nanorods) made from zinc oxide, then covered them with an active polymer to form a device that converts sunlight into electricity.

Using the special properties of the zinc oxide material, the team was able to show that sound levels as low as 75 decibels (equivalent to a typical roadside noise or a printer in an office) could significantly improve the solar cell performance.

“After investigating systems for converting vibrations into electricity this is a really exciting development that shows a similar set of physical properties can also enhance the performance of a photovoltaic,” said Dr Steve Dunn, Reader in Nanoscale Materials from Queen Mary’s School of Engineering and Materials Science.

Scientists had previously shown that applying pressure or strain to zinc oxide materials could result in voltage outputs, known as the piezoelectric effect. However, the effect of these piezoelectric voltages on solar cell efficiency had not received significant attention before.

“We thought the soundwaves, which produce random fluctuations, would cancel each other out and so didn’t expect to see any significant overall effect on the power output,” said James Durrant, Professor of Photochemistry at Imperial College London, who co-led the study.

“The key for us was that not only that the random fluctuations from the sound didn’t cancel each other out, but also that some frequencies of sound seemed really to amplify the solar cell output – so that the increase in power was a remarkably big effect considering how little sound energy we put in.”

“We tried playing music instead of dull flat sounds, as this helped us explore the effect of different pitches. The biggest difference we found was when we played pop music rather than classical, which we now realise is because our acoustic solar cells respond best to the higher pitched sounds present in pop music,” he concluded.

The discovery could be used to power devices that are exposed to acoustic vibrations, such as air conditioning units or within cars and other vehicles.

This is not the first time that music has been shown to affect properties at the nanoscale. A March 12, 2008 article by Anna Salleh for the Australian Broadcasting Corporation featured a researcher who tested nanowire growth by playing music (Note: Links have been removed),

Silicon nanowires grow more densely when blasted with Deep Purple than any other music tested, says an Australian researcher.

But the exact potential of music in growing nanowires remains a little hazy.

David Parlevliet, a PhD student at Murdoch University in Perth, presented his findings at a recent Australian Research Council Nanotechnology Network symposium in Melbourne.

Parlevliet is testing nanowires for their ability to absorb sunlight in the hope of developing solar cells from them.

I’ve taken a look at the references cited by researchers in their paper and there is nothing from Parleviet listed, so, this seems to be one of those cases where more than one scientist is thinking along the similar lines, i.e., that sound might affect nanoscale structures in such a way as to improve solar cell efficiency.

Here’s a link to and a citation for the ICL/University of Queen Mary research paper,

Acoustic Enhancement of Polymer/ZnO Nanorod Photovoltaic Device Performance by Safa Shoaee, Joe Briscoe, James R. Durrant, Steve Dunn. Article first published online: 6 NOV 2013 DOI: 10.1002/adma.201303304
© 2013 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim

This paper is behind a paywall.

The brain and poetry; congratulations to Alice Munro on her 2013 Nobel prize

There’s an intriguing piece of research from the University of Exeter (UK) about poetry and the brain. From an Oct. 9, 2013 University of Exeter news release (also on EurekAlert),

New brain imaging technology is helping researchers to bridge the gap between art and science by mapping the different ways in which the brain responds to poetry and prose.

Scientists at the University of Exeter used state-of-the-art functional magnetic resonance imaging (fMRI) technology, which allows them to visualise which parts of the brain are activated to process various activities. No one had previously looked specifically at the differing responses in the brain to poetry and prose.

In research published in the Journal of Consciousness Studies, the team found activity in a “reading network” of brain areas which was activated in response to any written material. But they also found that more emotionally charged writing aroused several of the regions in the brain which respond to music. These areas, predominantly on the right side of the brain, had previously been shown as to give rise to the “shivers down the spine” caused by an emotional reaction to music. .

When volunteers read one of their favourite passages of poetry, the team found that areas of the brain associated with memory were stimulated more strongly than ‘reading areas’, indicating that reading a favourite passage is a kind of recollection.

In a specific comparison between poetry and prose, the team found evidence that poetry activates brain areas, such as the posterior cingulate cortex and medial temporal lobes, which have been linked to introspection.

I did find the Journal of Consciousness Studies in two places (here [current issues] and here [archived issues]) but can’t find the article in my admittedly speedy searches on the website and via Google. Unfortunately the university news release did not include a citation (as so many of them now do); presumably the research will be published soon.

I’d like to point out a couple of things about the research, the sample was small (13) and not randomized (faculty and students from the English department). From the news release,

Professor Adam Zeman, a cognitive neurologist from the University of Exeter Medical School, worked with colleagues across Psychology and English to carry out the study on 13 volunteers, all faculty members and senior graduate students in English. Their brain activity was scanned and compared when reading literal prose such as an extract from a heating installation manual, evocative passages from novels, easy and difficult sonnets, as well as their favourite poetry.

Professor Zeman said: “Some people say it is impossible to reconcile science and art, but new brain imaging technology means we are now seeing a growing body of evidence about how the brain responds to the experience of art. This was a preliminary study, but it is all part of work that is helping us to make psychological, biological, anatomical sense of art.”

Arguably, people who’ve spent significant chunks of their lives studying and reading poetry and prose might have developed capacities the rest of us have not. For a case in point, there’s a Sept. 26, 2013 news item on ScienceDaily about research on ballet dancers’ brains and their learned ability to suppress dizziness,

The research suggests that years of training can enable dancers to suppress signals from the balance organs in the inner ear.

Normally, the feeling of dizziness stems from the vestibular organs in the inner ear. These fluid-filled chambers sense rotation of the head through tiny hairs that sense the fluid moving. After turning around rapidly, the fluid continues to move, which can make you feel like you’re still spinning.

Ballet dancers can perform multiple pirouettes with little or no feeling of dizziness. The findings show that this feat isn’t just down to spotting, a technique dancers use that involves rapidly moving the head to fix their gaze on the same spot as much as possible.

Researchers at Imperial College London recruited 29 female ballet dancers and, as a comparison group, 20 female rowers whose age and fitness levels matched the dancers’.

The volunteers were spun around in a chair in a dark room. They were asked to turn a handle in time with how quickly they felt like they were still spinning after they had stopped. The researchers also measured eye reflexes triggered by input from the vestibular organs. Later, they examined the participants’ brain structure with MRI scans.

In dancers, both the eye reflexes and their perception of spinning lasted a shorter time than in the rowers.

Yes, they too have a small sample. Happily, you can find a citation and a link to the research at the end of the ScienceDaily news item.

ETA Oct. 10, 2013 at 1:10 pm PDT: The ballet dancer research was not randomized but  that’s understandable as researchers were trying to discover why these dancers don’t experience dizziness. It should be noted the researchers did test the ballet dancers against a control group. By contrast, the researchers at the University of Exeter seemed to be generalizing results from a specialized sample to a larger population.

Alice Munro news

It was announced today (Thursday, Oct. 10, 2013) that Canada’s Alice Munro has been awarded the 2013 Nobel Prize for Literature. Here’s more from an Oct. 10, 2013 news item on the Canadian Broadcasting Corporation (CBC) news website,

Alice Munro wins the 2013 Nobel Prize in Literature, becoming the first Canadian woman to take the award since its launch in 1901.

Munro, 82, only the 13th woman given the award, was lauded by the Swedish Academy during the Nobel announcement in Stockholm as the “master of the contemporary short story.”

“We’re not saying just that she can say a lot in just 20 pages — more than an average novel writer can — but also that she can cover ground. She can have a single short story that covers decades, and it works,” said Peter Englund, permanent secretary of the Swedish Academy.

Reached in British Columbia by CBC News on Thursday morning, Munro said she always viewed her chances of winning the Nobel as “one of those pipe dreams” that “might happen, but it probably wouldn’t.”

Congratulations Ms. Munro! For the curious, there’s a lot more about Alice Munro and about her work in the CBC news item.

Controlling crystal growth for plastic electronics

A July 4, 2013 news item on Nanowerk highlights research into plastic electronics taking place at Imperial College London (ICL), Note: A link has been removed,

Scientists have discovered a way to better exploit a process that could revolutionise the way that electronic products are made.

The scientists from Imperial College London say improving the industrial process, which is called crystallisation, could revolutionise the way we produce electronic products, leading to advances across a whole range of fields; including reducing the cost and improving the design of plastic solar cells.

The process of making many well-known products from plastics involves controlling the way that microscopic crystals are formed within the material. By controlling the way that these crystals are grown engineers can determine the properties they want such as transparency and toughness. Controlling the growth of these crystals involves engineers adding small amounts of chemical additives to plastic formulations. This approach is used in making food boxes and other transparent plastic containers, but up until now it has not been used in the electronics industry.

The team from Imperial have now demonstrated that these additives can also be used to improve how an advanced type of flexible circuitry called plastic electronics is made.

The team found that when the additives were included in the formulation of plastic electronic circuitry they could be printed more reliably and over larger areas, which would reduce fabrication costs in the industry.

The team reported their findings this month in the journal Nature Materials (“Microstructure formation in molecular and polymer semiconductors assisted by nucleation agents”).

The June 7, 2013 Imperial College London news release by Joshua Howgego, which originated the news item, describes the researchers and the process in more detail,

Dr Natalie Stingelin, the leader of the study from the Department of Materials and Centre of Plastic Electronics at Imperial, says:

“Essentially, we have demonstrated a simple way to gain control over how crystals grow in electrically conducting ‘plastic’ semiconductors. Not only will this help industry fabricate plastic electronic devices like solar cells and sensors more efficiently. I believe it will also help scientists experimenting in other areas, such as protein crystallisation, an important part of the drug development process.”

Dr Stingelin and research associate Neil Treat looked at two additives, sold under the names IrgaclearÒ XT 386 and MilladÒ 3988, which are commonly used in industry. These chemicals are, for example, some of the ingredients used to improve the transparency of plastic drinking bottles. The researchers experimented with adding tiny amounts of these chemicals to the formulas of several different electrically conducting plastics, which are used in technologies such as security key cards, solar cells and displays.

The researchers found the additives gave them precise control over where crystals would form, meaning they could also control which parts of the printed material would conduct electricity. In addition, the crystallisations happened faster than normal. Usually plastic electronics are exposed to high temperatures to speed up the crystallisation process, but this can degrade the materials. This heat treatment treatment is no longer necessary if the additives are used.

Another industrially important advantage of using small amounts of the additives was that the crystallisation process happened more uniformly throughout the plastics, giving a consistent distribution of crystals.  The team say this could enable circuits in plastic electronics to be produced quickly and easily with roll-to-roll printing procedures similar to those used in the newspaper industry. This has been very challenging to achieve previously.

Dr Treat says: “Our work clearly shows that these additives are really good at controlling how materials crystallise. We have shown that printed electronics can be fabricated more reliably using this strategy. But what’s particularly exciting about all this is that the additives showed fantastic performance in many different types of conducting plastics. So I’m excited about the possibilities that this strategy could have in a wide range of materials.”

Dr Stingelin and Dr Treat collaborated with scientists from the University of California Santa Barbara (UCSB), and the National Renewable Energy Laboratory in Golden, US, and the Swiss Federal Institute of Technology on this study. The team are planning to continue working together to see if subtle chemical changes to the additives improve their effects – and design new additives.

There are some big plans for this discovery, from the news release,

They [the multinational team from ICL, UCSB, National Renewable Energy Laboratory, and Swiss Federal Institute of Technology]  will be working with the new Engineering and Physical Sciences Research Council (EPSRC)-funded Centre for Innovative Manufacturing in Large Area Electronics in order to drive the industrial exploitation of their process. The £5.6 million of funding for this centre, to be led by researchers from Cambridge University, was announced earlier this year [2013]. They are also exploring collaborations with printing companies with a view to further developing their circuit printing technique.

For the curious, here’s a link to and a citation for the published paper,

Microstructure formation in molecular and polymer semiconductors assisted by nucleation agents by Neil D. Treat, Jennifer A. Nekuda Malik, Obadiah Reid, Liyang Yu, Christopher G. Shuttle, Garry Rumbles, Craig J. Hawker, Michael L. Chabinyc, Paul Smith, & Natalie Stingelin. Nature Materials 12, 628–633 (2013) doi:10.1038/nmat3655 Published online 02 June 2013

This article is open access (at least for now).

Erasing time to create a temporal invisibility cloak

The idea of taking an eraser and just rubbing out embarrassing (or worse) incidents in one’s life is tempting but not yet possible despite efforts by researchers at Purdue University (Indiana, US). From a June 5, 2013 news item on ScienceDaily,

Researchers have demonstrated a method for “temporal cloaking” of optical communications, representing a potential tool to thwart would-be eavesdroppers and improve security for telecommunications.

“More work has to be done before this approach finds practical application, but it does use technology that could integrate smoothly into the existing telecommunications infrastructure,” said Purdue University graduate student Joseph Lukens, working with Andrew Weiner, the Scifres Family Distinguished Professor of Electrical and Computer Engineering.

Other researchers in 2012 invented temporal cloaking, but it cloaked only a tiny fraction — about a 10,000th of a percent — of the time available for sending data in optical communications. Now the Purdue researchers have increased that to about 46 percent, potentially making the concept practical for commercial applications.

The Purdue University June 5, 2013 news release, which originated the news item, describes the new technique,

The technique works by manipulating the phase, or timing, of light pulses. The propagation of light can be likened to waves in the ocean. If one wave is going up and interacts with another wave that’s going down, they cancel each other and the light has zero intensity. The phase determines the level of interference between these waves.

“By letting them interfere with each other you are able to make them add up to a one or a zero,” Lukens said. “The zero is a hole where there is nothing.”

Any data in regions where the signal is zero would be cloaked.

Controlling phase allows the transmission of signals in ones and zeros to send data over optical fibers. A critical piece of hardware is a component called a phase modulator, which is commonly found in optical communications to modify signals.

In temporal cloaking, two phase modulators are used to first create the holes and two more to  cover them up, making it look as though nothing was done to the signal.

“It’s a potentially higher level of security because it doesn’t even look like you are communicating,” Lukens said. “Eavesdroppers won’t realize the signal is cloaked because it looks like no signal is being sent.”

Such a technology also could find uses in the military, homeland security or law enforcement.

“It might be used to prevent communication between people, to corrupt their communication links without them knowing,” he said. “And you can turn it on and off, so if they suspected something strange was going on you could return it to normal communication.”

The technique could be improved to increase its operational bandwidth and the percentage of cloaking beyond 46 percent, he said.

In a July 14, 2011 posting I wrote about some of the research that laid the groundwork for this breakthrough at Purdue University,

Ian Sample in his July 13, 2011 posting on The Guardian Science blogs describes an entirely different approach, one that focusses on cloaking events rather than objects. From Samples’s posting,

The theoretical prospect of a “space-time” cloak – or “history editor” – was raised by Martin McCall and Paul Kinsler at Imperial College in a paper published earlier this year. The physicists explained that when light passes through a material, such as a lens, the light waves slow down. But it is possible to make a lens that splits the light in two, so that half – say the shorter wavelengths – speed up, while the other half, the longer wavelengths, slow down. This opens a gap in the light in which an event can be hidden, because half the light arrives before it has happened, and the other half arrives after the event.

In their paper, McCall and Kinsler outline a scenario whereby a video camera would be unable to record a crime being committed because there was a means of splitting the light such that 1/2 of it reached the camera before the crime occurred and the other 1/2  reached the camera afterwards. Fascinating, non?

It seems researchers at Cornell University have developed a device that can in a rudimentary fashion cloak events (from Samples’s posting),

The latest device, which has been shown to work for the first time by Moti Fridman and Alexander Gaeta at Cornell University, goes beyond the more familiar invisibility cloak, which aims to hide objects from view, by making entire events invisible.

Zeeya Merali in her extensive June 5, 2013 article (Temporal cloak erases data from history) for Nature provides an in depth explanation of the Purdue research,

To speed up the cloaking rate, Lukens and his colleagues exploited a wave phenomenon that was first discovered by British inventor Henry Fox Talbot in 1836. When a light wave passes through a series of parallel slits called a diffraction grating, it splits apart. The rays emanating from the slits combine on the other side to create an intricate interference pattern of peaks and troughs. Talbot discovered that this pattern repeats at regular intervals, creating what is now known as a Talbot carpet. There is also a temporal version of this effect in which you manipulate light over time to generate regular periods with zero light intensity, says Lukens. Data can be then be hidden in these holes in time.

Lukens’ team created its Talbot carpet in time by passing laser light through a ‘phase modulator’, a waveguide that also had an oscillating electrical voltage applied to it. As the voltage varied, the speed at which the light travelled through the waveguide was altered, splitting the light into its constituent frequencies and knocking these out of step. As predicted, at regular time intervals, the separate frequencies recombined destructively to generate time holes. Lukens’ team then used a second round of phase modulation to compress the energy further, expanding the duration of the time windows to 36 picoseconds (or 36 trillionths of a second).

The researchers tested the cloak to see if it was operating correctly by inserting a separate encoded data stream into the fibre during the time windows. They then applied two more rounds of phase modulation — to “undo the damage of the first two rounds”, says Lukens — decompressing the energy again and then combining the separated frequencies back into one. They confirmed that a user downstream would pick up the original laser signal alone, as though it had never been disturbed. The cloak successfully hid data added at a rate of 12.7 gigabits per second.

Unfortunately, the researchers were a little too successful and managed to erase the event entirely, which seems to answer a question I posed facetiously in my July 14, 2011 posting,

If you can’t see the object (light bending cloak), and you never saw the event (temporal cloak), did it exist and did it happen?

In addition to the military applications that Lukens imagines for temporal invisibility cloaks, Merali notes a another possibility in her Nature article,

Ironically, the first application of temporal cloaks may not be to hide data, but to help them to be read more accurately. The team has shown that splitting and recombining light waves in time creates increased periods in which the main data stream can be made immune to corruption by inserted data. “This could be useful to cut down crosstalk when multiple data streams share the same fibre,” says Lukens.

Gaeta agrees that the primary use for cloaking will probably be for innocent, mundane purposes. “People always imagine doing something illicit when they hear ‘cloaking’,” he says. “But these ways for manipulating light will probably be used to make current non-secret communication techniques more sophisticated.”

The research paper can be found here,

A temporal cloak at telecommunication data rate by Joseph M. Lukens, Daniel E. Leaird & Andrew M. Weiner. Nature (2013) doi:10.1038/nature12224 Published online 05 June 2013

This paper is behind a paywall. Fortunately, anyone can access my June 5, 2013 posting (Memories, science, archiving, and authenticity) which seems relevant here for two reasons. First, there’s a mention of a new open access initiative in the US which would make this research more freely available in the future with a proposal (there may be others as this initiative develops) called the Clearinghouse for the Open Research of the United States (CHORUS).  I imagine there would be some caveats and I notice that Nature magazine has signed up for this proposal. I think the second reason for mentioning yesterday’s post is pretty obvious, memory/erasing, etc.

COllaborative Network for Training in Electronic Skin Technology (CONTEST) looking for twelve researchers

The CONTEST (COllaborative Network for Training in Electronic Skin TechnologyCOllaborative Network for Training in Electronic Skin Technology) project was launched today in Italy. According to the Aug. 21, 2012 news item on Nanowerk,

“Flexible electronics” is one of the most significant challenges in the field of future electronics. The possibility of realizing flexible and bendable electronic circuits, that can be rolled up, twisted or inserted in films around objects, would introduce a range of infinite applications in multiple fields, including healthcare, robotics and energy.

In this area, the Fondazione Bruno Kessler of Trento will coordinate the CONTEST project (COllaborative Network for Training in Electronic Skin Technology), an Initial Training Network (ITN) Marie Curie project funded by the European Commission involving European research, academic and business players. These include seven full partners (Fondazione Bruno Kessler, Italy; ST Microelectronics, Italy; Technical University Munich, Germany; Fraunhofer EMFT, Germany; University College London, UK; Imperial College London, UK; and Shadow Robotics Company, UK) and two associate partners (University of Cambridge, UK, and University of Tokyo, Japan).

The CONTEST project page at the Fondazione Bruno Kessler website offers more details,

At the heart of the CONTEST programme lies the multidisciplinary research training of young researchers. The CONTEST network will recruit twelve excellent Early-Stage Researchers (e.g. PhD students) and two Experienced Researchers (e.g. Post-Doc fellows). Information for submitting applications is available at the project’s website: http://www.contest-itn.eu/.
CONTEST activities will be coordinated by Ravinder S. Dahiya, researcher at the Bio-MEMS Unit (BIO-Micro-Electro-Mechanical-Systems) of  the Center for Materials and Microsystems (Fondazione Bruno Kessler) and by Leandro Lorenzelli, head of the Bio-MEMS Unit.
“The disruptive flexible electronics technology – says Ravinder S. Dahiya – will create change and improve the electronic market landscape and usher in a new revolution in multifunctional electronics. It will transform to an unprecedented degree our view of electronics and how we, as a society, interact with intelligent and responsive systems.”
“The investigation, in a very multidisciplinary framework, of technological approaches for thin flexible components – explains Leandro Lorenzelli – will generate new paradigms and concepts for microelectronic devices and systems with new functionalities tailored to the needs of a wide range of applications including robotics, biomedical instrumentations and smart cities.”

Here’s more about the 12 researchers they’re recruiting, excerpted from the Job Openings page on the CONTEST project website (Note: I have removed some links),

We have been awarded a large interdisciplinary project on electronic skin and applications, called CONTEST (COllaborative Network for Training in Electronic Skin Technology). We are therefore looking for 12 excellent Early-Stage Researchers (e.g. PhD students) and 2 Experienced Researchers (e.g. Post-Doc), associated to:

  • Fondazione Bruno Kessler, Trento, Italy (2 Early-Stage Researcher positions on silicon based flexible sensors (e.g. touch sensors), electronic circuits and 1 Experienced Researcher position on system integration)  …,
  • ST Microelectronics, Catania, Italy (2 Early-Stage Researcher positions on chemical/physical sensors on flexible substrates, and metal patterned substrates for integrating flexible sensing elements)…,
  • Technical University Munich, Germany (3 Early-Stage Researcher positions on organic semiconductor based electronics devices and circuits, modeling of flexible devices and sensors … , and artificial skin in humanoids…,
  • Fraunhofer EMFT, Munich, Germany (1 Early-Stage Researcher position on assembly on film substrates and foil integration as well as 1 Experienced Researcher position on reliability and ESD issues of components during flex integration) … ,
  • University College London, UK (2 Early-Stage Researcher positions on organic semiconductor based interconnects, solutions processed sensors, alternative on-skin energy schemes, patterning of e-skin and stretchable interconnects using blends of graphene in polymeric materials …
  • Imperial College London, UK (1 Early-Stage Researcher position on human sensori-motor control and robotics) …, and
  • Shadow Robotics Company, UK (1 Early-Stage Researcher position on biorobotics and mechatronics) ….

Mobility rules apply to all these positions. Researchers can be of any nationality. They are required to undertake trans-national mobility (i.e. move from one country to another) when taking up their appointment. One general rule applies to the appointment of researchers: At the time of recruitment by the host organization, researchers must not have resided or carried out their main activity (work, studies, etc.) in the country of their host organization (i.e. recruiting institute) for more than 12 months in the 3 years immediately prior to the reference date. Short stays such as holidays and/or compulsory national service are not taken into account.

Good luck to all who apply! Priority will be given to applications received by Sept. 30, 2012.