physicsworld--2020-10-06--Roger Penrose, Reinhard Genzel and Andrea Ghez bag the Nobel Prize for Physics - Physics World

The 2020 Nobel Prize for Physics has been awarded to Roger Penrose , Reinhard Genzel and Andrea Ghez for their work on black holes .
The prize is worth 10 million Swedish krona ( about $ 1.1 million ) and half goes to Penrose , with Genzel and Ghez sharing the other half of the prize .
The Nobel Committee cites Penrose “ for the discovery that black hole formation is a robust prediction of the general theory of relativity ” , and Genzel and Ghez “ for the discovery of a supermassive compact object at the centre of our @ @ @ @ @ @ @ made this morning by the Royal Swedish Academy of Sciences , Ghez answered questions remotely from the US .
When asked what went through her mind when she first thought there was a huge black hole lurking in the middle of the Milky Way , Ghez replied “ The first thing was doubt that you ’ re really seeing what you think you ’ re seeing .
Doubt and excitement – that feeling that you ’ re at the frontier of research.
” On being the fourth woman to win the physics Nobel @ @ @ @ @ @ @ m thrilled to receive the prize and take very seriously the responsibility with being the fourth woman to win the Nobel prize .
I hope I can inspire other young women into the field – it ’ s a field that has so many pleasures .
And if you ’ re passionate about science there are so many things that can be done.
” Since the 18th century , physicists have speculated about the existence of objects so massive that even light can not escape their gravitational pull .
However , it was @ @ @ @ @ @ @ Albert Einstein created his general theory of relativity that scientists had the mathematical tools to investigate black holes with mathematical precision .
But even then , there was confusion over whether a black hole could form in nature .
One concern at the time was the idea that any departure from perfect spherical symmetry of an object could prevent it from collapsing to a singularity – a single point in space and time .
This was an important consideration because rotating stars do not have spherical symmetry .
In 1965 Penrose developed new @ @ @ @ @ @ @ could collapse to a black hole and devised a rigorous proof that the formation of a black hole is entirely consistent with general relativity .
In particular , he introduced the concept of the “ trapped surface ” – a closed 2D surface with the property that all light rays orthogonal to the surface converge when traced toward the future .
A trapped surface is formed in the early stages of the gravitational collapse of a star and once it has formed , the system must collapse to a singularity , creating a @ @ @ @ @ @ @ that this applies irrespective of the symmetry of the collapsing object .
As well as being the first major contribution to general relativity since Einstein , Penrose ’ s work inspired generations of astrophysicists and astronomers to work towards observing black holes .
“ It was Penrose , more than anyone else , who triggered the renaissance in relativity in the 1960s through his introduction of new mathematical techniques , ” says the UK ’ s Astronomer Royal , Martin Rees .
Also in the mid-1960s , astronomers and astrophysicists were beginning to @ @ @ @ @ @ @ at the centres of some galaxies was created by matter falling into black holes that were millions or even billions of times more massive than the Sun .
However , verifying that these active galactic nuclei ( AGNs ) contained black holes proved to be very difficult because telescopes did not have the resolution to distinguish between a black hole and a tight cluster of stars – which could also be lurking at the centres of galaxies .
A way around this problem is to study the motions of stars that orbit close @ @ @ @ @ @ @ are orbiting a black hole , their speeds should have a specific relationship with their distance from the black hole – as do planets orbiting the Sun .
However , if the stars are orbiting a cluster of stars , a different speed–distance relationship is expected .
Teams led by Ghez and Genzel studied a star that takes about 16 years to orbit the AGN at the centre of the Milky Way .
The star has a highly elliptical orbit and gets to within 17 light-hours from the AGN .
Independent analyses of @ @ @ @ @ @ @ teams suggests that it is orbiting an extremely compact object that with a mass of about 4 million Suns .
The only reasonable interpretation of this is that there is a supermassive black hole at the centre of the galaxy .
Laura Nuttall , who studies black-hole mergers at Portsmouth University told Physics World “ It ’ s great to see Penrose , Ghez and Genzel recognized with the Nobel prize .
Penrose is synonymous with black holes .
His work in proving how black holes form , as well as their centre @ @ @ @ @ @ @ many fields , including that of searching for gravitational waves.
” She adds , “ Ghez and Genzel ’ s work has also inspired many , such as the Event Horizon Telescope , which only released an image of a supermassive black hole last year .
It ’ s wonderful , that their work is very much taken as a given today – of course black holes form from the collapse of matter and of course there ’ s a black hole at the centre of the galaxy .
It ’ s easy @ @ @ @ @ @ @ been the case !
” Ghez was born in 1965 in the New York City , US .
She received a BS in physics from the Massachusetts Institute of Technology in 1987 and a PhD at the California Institute of Technology in 1992 .
After a year at the University of Arizona , she moved to the University of California , Los Angeles in 1994 where she has remained since .
Genzel was born in 1952 in Bad Homburg vor der Höhe , Germany .
He studied physics at the University of Freiburg @ @ @ @ @ @ @ at the University of Bonn in 1978 .
He then moved to the US working first at the Harvard-Smithsonian Center for Astrophysics until 1980 and then the Space Sciences Laboratory at the University of California , Berkeley until 1985 .
After a year as a professor at the University of California , Berkeley , he became a director of the Max Planck Institute for Extraterrestrial Physics in 1986 .
Since 1999 Genzel has held a joint appointment between the Max Planck Institute for Extraterrestrial Physics and the University of California , Berkeley .
@ @ @ @ @ @ @ , UK .
He did a BSc in mathematics at University College London before completing a PhD in algebraic geometry at the University of Cambridge in 1957 .
After spending time at Princeton and Syracuse universities in the US in 1959–1961 , he returned to England to King ’ s College London before heading to the University of Texas at Austin in 1963–1964 .
Penrose then moved to Birkbeck College , London until 1973 before heading to the University of Oxford , where he has remained since .

New laureates: Roger Penrose, Reinhard Genzel and Andrea Ghez have won the the 2020 Nobel Prize for Physics. (Courtesy: IOP Publishing/Tushna Commissariat; CC-BY-SA H Garching; UCLA/Christopher Dibble)
The 2020 Nobel Prize for Physics has been awarded to Roger Penrose, Reinhard Genzel and Andrea Ghez for their work on black holes.
The prize is worth 10 million Swedish krona (about $1.1 million) and half goes to Penrose, with Genzel and Ghez sharing the other half of the prize.
The Nobel Committee cites Penrose “for the discovery that black hole formation is a robust prediction of the general theory of relativity”, and Genzel and Ghez “for the discovery of a supermassive compact object at the centre of our galaxy”.
After the announcement was made this morning by the Royal Swedish Academy of Sciences, Ghez answered questions remotely from the US.
Doubt and excitement
When asked what went through her mind when she first thought there was a huge black hole lurking in the middle of the Milky Way, Ghez replied “The first thing was doubt that you’re really seeing what you think you’re seeing. Doubt and excitement – that feeling that you’re at the frontier of research.”
On being the fourth woman to win the physics Nobel prize, Ghez said “I’m thrilled to receive the prize and take very seriously the responsibility with being the fourth woman to win the Nobel prize. I hope I can inspire other young women into the field – it’s a field that has so many pleasures. And if you’re passionate about science there are so many things that can be done.”
Since the 18th century, physicists have speculated about the existence of objects so massive that even light cannot escape their gravitational pull. However, it was not until the early 20th century when Albert Einstein created his general theory of relativity that scientists had the mathematical tools to investigate black holes with mathematical precision.
Can black holes form?
But even then, there was confusion over whether a black hole could form in nature. One concern at the time was the idea that any departure from perfect spherical symmetry of an object could prevent it from collapsing to a singularity – a single point in space and time. This was an important consideration because rotating stars do not have spherical symmetry.
In 1965 Penrose developed new mathematical tools for describing how a star could collapse to a black hole and devised a rigorous proof that the formation of a black hole is entirely consistent with general relativity. In particular, he introduced the concept of the “trapped surface” – a closed 2D surface with the property that all light rays orthogonal to the surface converge when traced toward the future. A trapped surface is formed in the early stages of the gravitational collapse of a star and once it has formed, the system must collapse to a singularity, creating a black hole. Crucially, Penrose showed that this applies irrespective of the symmetry of the collapsing object.
As well as being the first major contribution to general relativity since Einstein, Penrose’s work inspired generations of astrophysicists and astronomers to work towards observing black holes.
“Renaissance in relativity”
“It was Penrose, more than anyone else, who triggered the renaissance in relativity in the 1960s through his introduction of new mathematical techniques,” says the UK’s Astronomer Royal, Martin Rees.
Also in the mid-1960s, astronomers and astrophysicists were beginning to think that light emitted from bright regions at the centres of some galaxies was created by matter falling into black holes that were millions or even billions of times more massive than the Sun. However, verifying that these active galactic nuclei (AGNs) contained black holes proved to be very difficult because telescopes did not have the resolution to distinguish between a black hole and a tight cluster of stars – which could also be lurking at the centres of galaxies.
A way around this problem is to study the motions of stars that orbit close to the AGN. If the stars are orbiting a black hole, their speeds should have a specific relationship with their distance from the black hole – as do planets orbiting the Sun. However, if the stars are orbiting a cluster of stars, a different speed–distance relationship is expected.
Highly elliptical orbit
Teams led by Ghez and Genzel studied a star that takes about 16 years to orbit the AGN at the centre of the Milky Way. The star has a highly elliptical orbit and gets to within 17 light-hours from the AGN. Independent analyses of the motion of the star by both teams suggests that it is orbiting an extremely compact object that with a mass of about 4 million Suns. The only reasonable interpretation of this is that there is a supermassive black hole at the centre of the galaxy.
Laura Nuttall, who studies black-hole mergers at Portsmouth University told Physics World “It’s great to see Penrose, Ghez and Genzel recognized with the Nobel prize. Penrose is synonymous with black holes. His work in proving how black holes form, as well as their centre being a singularity, has opened so many fields, including that of searching for gravitational waves.”
She adds, “Ghez and Genzel’s work has also inspired many, such as the Event Horizon Telescope, which only released an image of a supermassive black hole last year. It’s wonderful, that their work is very much taken as a given today – of course black holes form from the collapse of matter and of course there’s a black hole at the centre of the galaxy. It’s easy to forget that this has not always been the case!”
Ghez was born in 1965 in the New York City, US. She received a BS in physics from the Massachusetts Institute of Technology in 1987 and a PhD at the California Institute of Technology in 1992. After a year at the University of Arizona, she moved to the University of California, Los Angeles in 1994 where she has remained since.
Genzel was born in 1952 in Bad Homburg vor der Höhe, Germany. He studied physics at the University of Freiburg before completing a PhD in radio astronomy at the University of Bonn in 1978. He then moved to the US working first at the Harvard-Smithsonian Center for Astrophysics until 1980 and then the Space Sciences Laboratory at the University of California, Berkeley until 1985. After a year as a professor at the University of California, Berkeley, he became a director of the Max Planck Institute for Extraterrestrial Physics in 1986. Since 1999 Genzel has held a joint appointment between the Max Planck Institute for Extraterrestrial Physics and the University of California, Berkeley.
Penrose was born in 1931 in Colchester, UK. He did a BSc in mathematics at University College London before completing a PhD in algebraic geometry at the University of Cambridge in 1957. After spending time at Princeton and Syracuse universities in the US in 1959–1961, he returned to England to King’s College London before heading to the University of Texas at Austin in 1963–1964. Penrose then moved to Birkbeck College, London until 1973 before heading to the University of Oxford, where he has remained since.


physicsworld--2020-10-06--Flexible electronics make their way into the operating room - Physics World

A research team led by engineers at the George Washington University and Northwestern University has developed a new surgical tool containing advanced flexible electronics that could improve diagnosis and treatment of cardiac diseases .
Balloon catheters are often used during minimally invasive surgery or ablation procedures , where they are relied upon to carry out measurements and perform therapeutic functions when inserted through small incisions .
They can also be inserted into the heart to treat cardiac arrhythmias by locating and ablating the region of tissue causing the arrhythmia .
Currently , however , most balloon catheters are rigid , @ @ @ @ @ @ @ to the soft surfaces in the heart .
In addition , these devices can only perform one function at a time , requiring doctors to use multiple catheters throughout a procedure .
Using their experience in flexible and stretchable electronics , the researchers sought to create an elastic system that conforms to tissue surfaces and can act as both a diagnostic and therapeutic device in one .
The device is made up of stretchable gold interconnects sandwiched between a flexible polyimide sheet to form a flexible surface .
The catheter is not only @ @ @ @ @ @ @ 30 % in both directions without causing damage to the material .
The researchers employed existing manufacturing techniques commonly used in the semiconductor industry to produce each array on a temporary silicon wafer .
They then transferred the arrays to the soft elastomeric surface .
One of the features that makes this catheter unique is its multilayer design , with each layer having a unique purpose .
The layer on the outside , in contact with the skin , contains electrodes that carry out electrical readings and electrical stimulation of tissues .
The @ @ @ @ @ @ @ insulating layer of polyimide , contains temperature sensors .
These could allow surgeons to track changes in temperature of tissues in specific areas .
Finally , at the bottom is a layer containing pressure sensors , which measure local forces between heart tissue and the device .
The team tested the balloon catheter using computational models , plastic heart models , and real human and animal hearts .
They found that the catheter had advantages over current devices in both physical form and functionality .
The multilayered nature of the new catheter means @ @ @ @ @ @ @ therapeutic functions can be integrated into one device , allowing doctors to perform several measurements simultaneously and map them to specific areas .
This opens up the possibility that the device could automatically regulate properties like temperature throughout surgery .
“ We have taken new breakthrough materials and fabrication techniques typically employed by the semiconductor industry and applied them to the medical field , in this case cardiology , to advance a new class of medical instruments that will improve cardiac outcomes for patients and allow physicians to deliver better , safer and @ @ @ @ @ @ @ Efimov , a senior author of the study .
Details of the catheter are reported in Nature Biomedical Engineering .

Electrodes fixed to an inflated balloon catheter (Courtesy: John Rogers, Northwestern University)
A research team led by engineers at the George Washington University and Northwestern University has developed a new surgical tool containing advanced flexible electronics that could improve diagnosis and treatment of cardiac diseases.
Balloon catheters are often used during minimally invasive surgery or ablation procedures, where they are relied upon to carry out measurements and perform therapeutic functions when inserted through small incisions. They can also be inserted into the heart to treat cardiac arrhythmias by locating and ablating the region of tissue causing the arrhythmia. Currently, however, most balloon catheters are rigid, which means they cannot conform well to the soft surfaces in the heart. In addition, these devices can only perform one function at a time, requiring doctors to use multiple catheters throughout a procedure.
Using their experience in flexible and stretchable electronics, the researchers sought to create an elastic system that conforms to tissue surfaces and can act as both a diagnostic and therapeutic device in one.
Flexible arrangements
The device is made up of stretchable gold interconnects sandwiched between a flexible polyimide sheet to form a flexible surface. The catheter is not only flexible but can also stretch up to 30% in both directions without causing damage to the material.
The researchers employed existing manufacturing techniques commonly used in the semiconductor industry to produce each array on a temporary silicon wafer. They then transferred the arrays to the soft elastomeric surface.
One of the features that makes this catheter unique is its multilayer design, with each layer having a unique purpose. The layer on the outside, in contact with the skin, contains electrodes that carry out electrical readings and electrical stimulation of tissues. The next layer down, separated by an insulating layer of polyimide, contains temperature sensors. These could allow surgeons to track changes in temperature of tissues in specific areas. Finally, at the bottom is a layer containing pressure sensors, which measure local forces between heart tissue and the device.
New device could change surgery
The team tested the balloon catheter using computational models, plastic heart models, and real human and animal hearts. They found that the catheter had advantages over current devices in both physical form and functionality.
The multilayered nature of the new catheter means that a wide range of diagnostic and therapeutic functions can be integrated into one device, allowing doctors to perform several measurements simultaneously and map them to specific areas. This opens up the possibility that the device could automatically regulate properties like temperature throughout surgery.
“We have taken new breakthrough materials and fabrication techniques typically employed by the semiconductor industry and applied them to the medical field, in this case cardiology, to advance a new class of medical instruments that will improve cardiac outcomes for patients and allow physicians to deliver better, safer and more patient-specific care,” says Igor Efimov, a senior author of the study.
Details of the catheter are reported in Nature Biomedical Engineering.


physicsworld--2020-10-07--Gating and MLC tracking could increase access to real-time adaptive radiotherapy - Physics World

Stereotactic ablative radiotherapy ( SABR ) , in which high radiation doses are delivered over just a few fractions , requires management of intrafraction tumour motion to ensure accurate and safe treatment .
Such motion management is generally provided by dedicated commercial real-time tracking systems .
But according to new research from Australia , both multileaf collimator ( MLC ) tracking and gating can provide real-time motion adaptation on a standard linear accelerator .
These low-cost strategies have the capability to make SABR treatments more accessible .
Writing in Radiotherapy and Oncology , researchers from the ACRF Image X Institute @ @ @ @ @ @ @ other Australian cancer treatment centres evaluated radiation doses delivered to 44 prostate cancer patients when using MLC tracking and gating with a standard linac .
The patients were enrolled in the TROG 15.01 SPARK trial , which examined the use of kilovoltage ( kV ) intrafraction monitoring ( KIM ) to measure tumour position during treatment .
During the study , led by Paul Keall , professor of medical physics at the University of Sydney Medical School and director of the ACRF Image X Institute , and Jarad Martin , a radiation oncologist @ @ @ @ @ @ @ delivered 49 fractions using MLC tracking and 166 fractions using beam gating and couch shifts .
They performed motion tracking with KIM , which uses the linac ’ s on-board kV imager to acquire patient images during treatment .
Intrafraction KIM-guided motion adaption was then performed using MLC tracking for 10 patients or gating for 34 patients .
Of the 166 gated fractions , 65 included prostate motion that exceeded established thresholds and required treatment interruptions .
The researchers estimated the radiation doses that would have been delivered without motion adaptation and compared @ @ @ @ @ @ @ tracking or gating .
To evaluate the efficiency of gated treatments , they also calculated the time required to gate and perform a couch shift for each fraction .
Gated treatments proved to be efficient , taking between 5 and 19 min to complete , compared with 2 to 17 min for MLC tracking .
Couch shift interruptions lasted between 1 and 4 min .
Because KIM calculated the new couch position , the treatment team only needed enter the new values into the treatment system .
Both MLC tracking and gating delivered @ @ @ @ @ @ @ doses closer to the treatment plans than if no motion adaptation strategy had been used .
“ Both methods were effective at improving dose delivery accuracy that is crucial for high-dose treatments , ” says first author Emily Hewson .
“ While MLC tracking had a slight dosimetric improvement compared with gating , this difference was small , so either method could be used to provide accessible SBRT treatments for prostate cancer.
” Hewson notes that the variance of dose differences from the treatment plan was larger with gating than MLC tracking for @ @ @ @ @ @ @ suggest that while both strategies would perform similarly on average , gating would result in doses that deviated more from the plan for the worst cases , ” she adds .
The researchers suggest that MLC tracking might have been more accurate if a leaf width smaller than 5 mm had been used .
“ Smaller MLC leaves offer higher beam adaptation accuracy , which would benefit the small , slow motion that the prostate undergoes , ” explains Hewson .
“ Another alternative to improve accuracy would be to integrate MLC tracking @ @ @ @ @ @ @ the future to compensate for the finite MLC leaf width.
” Addressing the complexity of each strategy , Hewson says that treatment planning and implementation were comparable , but that the underlying software and quality assurance processes for MLC tracking are more complex than gating .
“ MLC tracking requires complex software to automatically adapt the treatment beam in real time , requiring more commissioning .
Also , each patient plan requires pre-treatment dosimetric quality assurance , ” she explains .
“ But implementing MLC tracking during treatment simply requires the treatment team @ @ @ @ @ @ @ adaptation is automated .
Gating requires more intervention by the treatment team if tumour motion exceeds the designated threshold.
” The researchers say that the accuracy of each adaptation method will be limited by the accuracy of the tumour localization method .
The 3D tumour localization accuracy of KIM in the trial was quantified to be 0.0±0.5 mm , 0.0±0.4 mm , and 0.0±0.5 mm in the anteroposterior , left–right , and superior-inferior directions , respectively .
“ KIM provides real-time tumour position in six degrees-of-freedom using fiducial markers that are MR-compatible and @ @ @ @ @ @ @ systems , ” the team write .
“ And because KIM utilizes the on-board kV imager that is already equipped on modern linacs , it potentially will allow widespread implementation of SABR.
” “ Our implementation of KIM to monitor tumour motion , combined with either gating or MLC tracking improves the availability of intrafraction motion adaption for all clinics with standard treatment machines , ” says Hewson .
“ One of the major barriers to implementing real-time adaptive radiotherapy in many countries has been a lack of finances and resources .
The @ @ @ @ @ @ @ these obstacles and bring intrafraction motion adaptation into standard clinical practice at any cancer treatment facility that treat patients using a modern linear accelerator .
”

The study employed kilovoltage intrafraction monitoring (KIM) to monitor prostate motion during high-dose radiotherapy delivered in five fractions. Treatment was adapted to the measured motion using either real-time MLC tracking or gating with couch shifts. (Courtesy: Julia Johnson)
Stereotactic ablative radiotherapy (SABR), in which high radiation doses are delivered over just a few fractions, requires management of intrafraction tumour motion to ensure accurate and safe treatment. Such motion management is generally provided by dedicated commercial real-time tracking systems. But according to new research from Australia, both multileaf collimator (MLC) tracking and gating can provide real-time motion adaptation on a standard linear accelerator. These low-cost strategies have the capability to make SABR treatments more accessible.
Writing in Radiotherapy and Oncology, researchers from the ACRF Image X Institute of the University of Sydney and four other Australian cancer treatment centres evaluated radiation doses delivered to 44 prostate cancer patients when using MLC tracking and gating with a standard linac. The patients were enrolled in the TROG 15.01 SPARK trial, which examined the use of kilovoltage (kV) intrafraction monitoring (KIM) to measure tumour position during treatment.
During the study, led by Paul Keall, professor of medical physics at the University of Sydney Medical School and director of the ACRF Image X Institute, and Jarad Martin, a radiation oncologist at Calvary Mater Newcastle, the researchers delivered 49 fractions using MLC tracking and 166 fractions using beam gating and couch shifts. They performed motion tracking with KIM, which uses the linac’s on-board kV imager to acquire patient images during treatment. Intrafraction KIM-guided motion adaption was then performed using MLC tracking for 10 patients or gating for 34 patients. Of the 166 gated fractions, 65 included prostate motion that exceeded established thresholds and required treatment interruptions.
KIM uses the kV imager on standard linacs to image a patient, and automatically segments the implanted fiducial markers to determine the 3D position of the tumour in real time. The real-time position information can be used to guide motion adaptation, to improve the accuracy of radiotherapy. (Courtesy: Julia Johnson)
The researchers estimated the radiation doses that would have been delivered without motion adaptation and compared these with doses delivered when employing MLC tracking or gating. To evaluate the efficiency of gated treatments, they also calculated the time required to gate and perform a couch shift for each fraction.
Gated treatments proved to be efficient, taking between 5 and 19 min to complete, compared with 2 to 17 min for MLC tracking. Couch shift interruptions lasted between 1 and 4 min. Because KIM calculated the new couch position, the treatment team only needed enter the new values into the treatment system.
First author Emily Hewson.
Both MLC tracking and gating delivered similar radiation doses, and both delivered doses closer to the treatment plans than if no motion adaptation strategy had been used. “Both methods were effective at improving dose delivery accuracy that is crucial for high-dose treatments,” says first author Emily Hewson. “While MLC tracking had a slight dosimetric improvement compared with gating, this difference was small, so either method could be used to provide accessible SBRT treatments for prostate cancer.”
Hewson notes that the variance of dose differences from the treatment plan was larger with gating than MLC tracking for the bladder and rectum. “Data suggest that while both strategies would perform similarly on average, gating would result in doses that deviated more from the plan for the worst cases,” she adds.
The researchers suggest that MLC tracking might have been more accurate if a leaf width smaller than 5 mm had been used. “Smaller MLC leaves offer higher beam adaptation accuracy, which would benefit the small, slow motion that the prostate undergoes,” explains Hewson. “Another alternative to improve accuracy would be to integrate MLC tracking with a real-time couch tracking method in the future to compensate for the finite MLC leaf width.”
Addressing the complexity of each strategy, Hewson says that treatment planning and implementation were comparable, but that the underlying software and quality assurance processes for MLC tracking are more complex than gating.
“MLC tracking requires complex software to automatically adapt the treatment beam in real time, requiring more commissioning. Also, each patient plan requires pre-treatment dosimetric quality assurance,” she explains. “But implementing MLC tracking during treatment simply requires the treatment team to open the MLC tracking software; adaptation is automated. Gating requires more intervention by the treatment team if tumour motion exceeds the designated threshold.”
The researchers say that the accuracy of each adaptation method will be limited by the accuracy of the tumour localization method. The 3D tumour localization accuracy of KIM in the trial was quantified to be 0.0±0.5 mm, 0.0±0.4 mm, and 0.0±0.5 mm in the anteroposterior, left–right, and superior-inferior directions, respectively.
“KIM provides real-time tumour position in six degrees-of-freedom using fiducial markers that are MR-compatible and smaller than beacons used with some commercial systems,” the team write. “And because KIM utilizes the on-board kV imager that is already equipped on modern linacs, it potentially will allow widespread implementation of SABR.”
“Our implementation of KIM to monitor tumour motion, combined with either gating or MLC tracking improves the availability of intrafraction motion adaption for all clinics with standard treatment machines,” says Hewson. “One of the major barriers to implementing real-time adaptive radiotherapy in many countries has been a lack of finances and resources. The adaptive methods we compared could potentially overcome these obstacles and bring intrafraction motion adaptation into standard clinical practice at any cancer treatment facility that treat patients using a modern linear accelerator.”


physicsworld--2020-10-07--Tiny ultrasound detector achieves super-resolution imaging - Physics World

A device described as the world ’ s smallest ultrasound detector has been created by Vasilis Ntziachristos and colleagues at the Technical University of Munich and Helmholtz Zentrum München .
The extremely sensitive device can image structures smaller than individual living cells and is made using inexpensive and readily available silicon-on-insulator technology .
With further optimization , the team says their detector could be mass-produced for use in a broad range of imaging applications .
Traditionally , ultrasound detectors use piezoelectric transducers to both broadcast high-frequency sound and also pick up sound that has reflected from target objects – using @ @ @ @ @ @ @ .
The spatial resolution of an ultrasound image can be improved by shrinking the size of the transducers , but this can drastically lower the sensitivity of the system .
Recently , optical detection techniques have been used to get around this resolution problem .
One approach has been to detect changes in the resonant properties of an optical cavity that are caused by ultrasound waves .
But so far , even the most advanced miniaturization techniques have not succeeded in confining light to dimensions smaller than about 50 microns , placing a @ @ @ @ @ @ @ achieved .
Ntziachristos ’ team has improved on these designs using silicon-on-insulator technology , which can be fabricated through techniques widely used in the semiconductor industry .
The researchers developed a “ silicon waveguide-etalon detector ” ( SWED ) .
The waveguide is contained in a periodic arrangement of Bragg gratings , each separated by spacers ; but with one grating replaced by a cavity .
A reflective layer of silver is then deposited on the end of the waveguide .
When Ntziachristos and colleagues pumped a continuous-wave laser into the SWED , @ @ @ @ @ @ @ induce characteristic intensity variations in the light reflected off the silver layer .
Furthermore , the high contrast between the cladding and cavity material enabled far better light confinement than had been achieved previously .
With a sensing area that is 220×500 nm in width , the SWED is a factor of 10 smaller than the diameter of a blood cell ; and 10,000 times smaller than previous resonator-based sensors .
The resulting spatial resolution made possible for Ntziachristos ’ team to image of structures 50 times smaller than the wavelength of the @ @ @ @ @ @ @ a capability called super-resolution imaging .
At the same time , the SWED is 1000 times more sensitive than current optical devices ; and some 100 million times more sensitive than piezoelectric detectors of the same size .
Such a significant improvement in both sensitivity and resolution mean that the SWED can fit onto a chip just half a micron in size .
This opens-up a wealth of opportunities for improvement in both medical and industrial imaging .
With further optimization , the device could soon be integrated into mass-produced , extremely dense @ @ @ @ @ @ @ ultra-fine details in materials and biological tissues .
It could also be used to study the fundamental properties of high-frequency sound waves , and their small-scale interactions with matter .
The new technology is described in Nature .

Sound idea: this silicon chip (3×6 mm) has multiple SWED detectors. The fine black engravings on the surface of the chip are the photonics circuits interconnecting the detectors, which are not visible. In the background is a larger scale photonics circuit on a silicon wafer. (Courtesy: Helmholtz Zentrum Muenchen / Roman Shnaiderman)
A device described as the world’s smallest ultrasound detector has been created by Vasilis Ntziachristos and colleagues at the Technical University of Munich and Helmholtz Zentrum München. The extremely sensitive device can image structures smaller than individual living cells and is made using inexpensive and readily available silicon-on-insulator technology. With further optimization, the team says their detector could be mass-produced for use in a broad range of imaging applications.
Traditionally, ultrasound detectors use piezoelectric transducers to both broadcast high-frequency sound and also pick up sound that has reflected from target objects – using the reflected signal to create an image. The spatial resolution of an ultrasound image can be improved by shrinking the size of the transducers, but this can drastically lower the sensitivity of the system.
Recently, optical detection techniques have been used to get around this resolution problem. One approach has been to detect changes in the resonant properties of an optical cavity that are caused by ultrasound waves. But so far, even the most advanced miniaturization techniques have not succeeded in confining light to dimensions smaller than about 50 microns, placing a constraint on the resolution that can be achieved.
Silicon-on-insulator technology
Ntziachristos’ team has improved on these designs using silicon-on-insulator technology, which can be fabricated through techniques widely used in the semiconductor industry. The researchers developed a “silicon waveguide-etalon detector” (SWED). The waveguide is contained in a periodic arrangement of Bragg gratings, each separated by spacers; but with one grating replaced by a cavity. A reflective layer of silver is then deposited on the end of the waveguide.
When Ntziachristos and colleagues pumped a continuous-wave laser into the SWED, they found that incident ultrasound waves could induce characteristic intensity variations in the light reflected off the silver layer. Furthermore, the high contrast between the cladding and cavity material enabled far better light confinement than had been achieved previously.
With a sensing area that is 220×500 nm in width, the SWED is a factor of 10 smaller than the diameter of a blood cell; and 10,000 times smaller than previous resonator-based sensors. The resulting spatial resolution made possible for Ntziachristos’ team to image of structures 50 times smaller than the wavelength of the ultrasound used to obtain the images – a capability called super-resolution imaging. At the same time, the SWED is 1000 times more sensitive than current optical devices; and some 100 million times more sensitive than piezoelectric detectors of the same size.
Such a significant improvement in both sensitivity and resolution mean that the SWED can fit onto a chip just half a micron in size. This opens-up a wealth of opportunities for improvement in both medical and industrial imaging. With further optimization, the device could soon be integrated into mass-produced, extremely dense ultrasound arrays, capable of picking out ultra-fine details in materials and biological tissues. It could also be used to study the fundamental properties of high-frequency sound waves, and their small-scale interactions with matter.
The new technology is described in Nature.


physicsworld--2020-10-07--Canadian Light Source overcomes geographic challenges while building local expertise - Physics World

What are the benefits of the CLS to the Canadian user community when compared to using facilities outside of the country ?
The Canadian science community has always had access to foreign facilities , including several dedicated beamlines at the now decommissioned Synchrotron Radiation Center in Wisconsin , in the 1980s .
But having a reliable and dedicated source for Canadian scientists has allowed for comprehensive , robust , and long-term research projects to be conducted , helping Canada maintain and secure scientific prominence in key scientific areas , including nanomaterials , agriculture , and protein crystallography , among many @ @ @ @ @ @ @ to specifically address Canada ’ s science needs and strategic priorities , with dedicated infrastructure for research in health , agriculture , energy and the environment , and advanced materials , while facilities in other countries have understandably been designed to support those nations ’ strategic interests .
Additionally , building a light source for and in Canada has encouraged the development of previously unavailable expertise in the design and manufacture of synchrotron components .
Several companies across the Canada now compete to deliver services and equipment to other synchrotron development projects around @ @ @ @ @ @ @ course we hope that scientific endeavour around the world remains collaborative , open and unaffected by political winds , it is important that our country maintains a reliable advanced light source for Canadian scientists to be able to access .
What are some of the challenges of running a national facility in a country where major population centres are separated by huge distances ?
Canada is the second largest country in world by area .
Indeed , the distance between Toronto and Vancouver , two of its major cities , is almost the @ @ @ @ @ @ @ Perhaps Canadians are simply used to this but we have all grown accustomed to calculating time zones ( six across the country ) for conference calls and adjusting in-person meeting schedules ( pre-COVID-19 ) to allow for everyone to recover from jetlag .
The CLS is located at the University of Saskatchewan in Saskatoon – which is not a major metropolitan area and is some distance from any large cities .
Has this relative isolation been a problem ?
If not , how has it been overcome ?
Because of Canada ’ s @ @ @ @ @ @ @ would have presented a bit of a challenge regardless of the site selected .
Being located in the centre of Canada has allowed for centralization , giving equal access to the theretofore largest provincial user groups ( Ontario to the east and British Columbia to the west ) but also , and importantly , it fuelled the growth of Saskatchewan ’ s provincial synchrotron user community .
Indeed , Saskatchewan grew from a single synchrotron user to more than 300 in 10 years , attracting research funding , faculty and graduate students from @ @ @ @ @ @ @ grant councils , especially the Natural Sciences and Engineering Research Council , have continuously funded travel for users to access the CLS in Saskatoon .
Although travel within Canada is known to be expensive compared to travel within Europe and the US , for instance , Canadian synchrotron users have been largely successful at accessing travel funding to use the CLS .
The benefits of having a synchrotron in a smaller community also include easy access from the airport , affordable accommodation , and lower overall ancillary costs .
Has the presence of @ @ @ @ @ @ @ that city and elsewhere in the Prairie region of Canada ?
The CLS caters to approximately 1000 scientists from academia , government and industry per year , approximately a third of them from the Prairies .
The CLS helps to train and educate hundreds of graduate students per year , attracts some of the most talented scientists in the world to Canada , fosters collaborations between Canadian and local scientists and colleagues at facilities around the world , and has created technologically advanced jobs and unique scientific and technical expertise in our province @ @ @ @ @ @ @ Canada ’ s and Saskatchewan ’ s international scientific reputation through publications in academic literature ( more than 5000 papers to date ) , through hosting international scientific conferences , and by bringing media attention to scientific discoveries .
The CLS collaborates with a number of other initiatives in the Prairies including the Protein Supercluster , the National Research Council ’ s Aquatic and Crop Resource Development Research Centre , and the Global Institute for Food Security .
Are there any plans to build complementary facilities in Saskatoon ?
For example , a @ @ @ @ @ @ @ “ Grenoble of the Prairies ” ?
The University of Saskatchewan , the CLS ’ s owner , is a leader in the effort to build a new dedicated neutron source for Canada .
It would be advantageous of course to have it near the CLS , in terms of the complementary nature of the research and the enormous possibilities for scientific cross-pollination , but there are no immediate plans to build a neutron source on our campus .
However , the proximity to the university – as well as the federal agriculture @ @ @ @ @ @ @ an innovation park renowned for its plant biotech companies – has created a cluster known for its global-leading agriculture expertise , which culminated in the recently funded Protein Industries Canada ( PIC ) , an industry-led , not-for-profit organization created to position Canada as a global source of high-quality plant protein and plant-based co-products .
What will the future bring for the CLS ?
Are there any major upgrade plans ?
The CLS is a third-generation facility and already brighter , faster and stronger fourth-generation light source facilities are being built around the @ @ @ @ @ @ @ globally competitive and a crucial resource for the Canadian scientific community for at least a decade , the national light source science community is developing plans for the next generation of Canadian synchrotron-enabled science .
Based on consultations with international machine-design experts as well as extensive engagement with the Canadian user community , a conceptual design report for CLS 2.0 is in development .
CLS 2.0 ’ s beam will be 700 times brighter and more coherent than the current CLS .
A brighter , faster and smaller light beam will enable scientists @ @ @ @ @ @ @ collect better data much faster , allowing for better scientific outcomes .
CLS 2.0 will be among the best light sources in the world and will enable the Canadian scientific community to remain a global leader .
What are some of the physics research highlights from the CLS over the past 16 years ?
Physics is the backbone of everything we do as a science facility – the accelerator and rings operate thanks to the expertise of our physicists and engineers – and it is a huge part of the research programme .
@ @ @ @ @ @ @ is a powerful tool for studying molecular vibrational dynamics , as Ohio State University and University of New Brunswick scientists showed by demonstrating the effects of quantum monodromy on the spectrum of cyanogen is-thiocyanate .
Our many X-ray beamlines can be put to several useful applications in physics research , most prominently in the recent discovery and exploration of charge density waves in cuprate superconductors .
Recently , our REIXS beamline was used by the Canadian Space Agency and NASA scientists to test and validate the performance of window shielding for an upcoming @ @ @ @ @ @ @ within the desired range , but no infrared light , could pass through .
Researchers from University of Toronto and King Abdullah University of Science and Technology have overcome a key obstacle in combining the emerging solar-harvesting technology of perovskites with the commercial gold standard – silicon solar cells .
The result is a highly efficient and stable tandem solar cell with the perovskites mixed as a liquid solar ink .
The CLS was used to show that the solution processing treatment left the perovskites ’ crystal structure untouched , leaving their basic @ @ @ @ @ @ @ one of the top X-ray scattering beamlines in the world in quantum materials research , was used to study a conductor-to-insulator phase change in samarium nickelate , a quantum material known as a strongly correlated electron system .
The dramatic phase change means that the material can be used as a very sensitive detector .
Indeed the team from the CLS , Argonne National Laboratory , Rutgers University , the National Institute of Standards and Technology , the Massachusetts Institute of Technology , Columbia University and the University of Massachusetts was inspired by @ @ @ @ @ @ @ mouth called the ampullae of Lorenzini , which is capable of detecting small electric fields from prey animals .
This of course is just a small subsection of the physics research at our facility , which also covers hydrophobics , catalyst structure , new imaging techniques and many other areas .

Physics World Big Science Briefing. You can enjoy the full issue Taken from the 2020. You can enjoy the full issue via the Physics World app
Isabelle Blain is chair of the board at the Canadian Light Source (CLS) in Saskatoon, Saskatchewan, and is a former vice-president of NSERC, Canada’s science and engineering granting council. Marie D’Iorio is a CLS board member, senior strategy adviser at the University of Ottawa and president of NanoCanada. Together, they answer Physics World’s questions about the CLS, which has been running for more than 16 years and is the first national synchrotron in Canada
Molecular probe Senior scientist Michel Fodje working on a beamline at CLS that is part of the Canadian Macromolecular Crystallography Facility. (Courtesy: Canadian Light Source)
What are the benefits of the CLS to the Canadian user community when compared to using facilities outside of the country?
The Canadian science community has always had access to foreign facilities, including several dedicated beamlines at the now decommissioned Synchrotron Radiation Center in Wisconsin, in the 1980s. But having a reliable and dedicated source for Canadian scientists has allowed for comprehensive, robust, and long-term research projects to be conducted, helping Canada maintain and secure scientific prominence in key scientific areas, including nanomaterials, agriculture, and protein crystallography, among many others.
The CLS was also built to specifically address Canada’s science needs and strategic priorities, with dedicated infrastructure for research in health, agriculture, energy and the environment, and advanced materials, while facilities in other countries have understandably been designed to support those nations’ strategic interests.
Additionally, building a light source for and in Canada has encouraged the development of previously unavailable expertise in the design and manufacture of synchrotron components. Several companies across the Canada now compete to deliver services and equipment to other synchrotron development projects around the world.
Finally, while of course we hope that scientific endeavour around the world remains collaborative, open and unaffected by political winds, it is important that our country maintains a reliable advanced light source for Canadian scientists to be able to access.
What are some of the challenges of running a national facility in a country where major population centres are separated by huge distances?
Canada is the second largest country in world by area. Indeed, the distance between Toronto and Vancouver, two of its major cities, is almost the same as from London to Cairo. Perhaps Canadians are simply used to this but we have all grown accustomed to calculating time zones (six across the country) for conference calls and adjusting in-person meeting schedules (pre-COVID-19) to allow for everyone to recover from jetlag.
View from the top Isabelle Blain (left) and Marie D’Iorio sit on the board of directors at the CLS. (Courtesy: Canadian Light Source)
The CLS is located at the University of Saskatchewan in Saskatoon – which is not a major metropolitan area and is some distance from any large cities. Has this relative isolation been a problem? If not, how has it been overcome?
Because of Canada’s expanse, the CLS’s location would have presented a bit of a challenge regardless of the site selected. Being located in the centre of Canada has allowed for centralization, giving equal access to the theretofore largest provincial user groups (Ontario to the east and British Columbia to the west) but also, and importantly, it fuelled the growth of Saskatchewan’s provincial synchrotron user community. Indeed, Saskatchewan grew from a single synchrotron user to more than 300 in 10 years, attracting research funding, faculty and graduate students from around the world.
Additionally, Canadian grant councils, especially the Natural Sciences and Engineering Research Council, have continuously funded travel for users to access the CLS in Saskatoon. Although travel within Canada is known to be expensive compared to travel within Europe and the US, for instance, Canadian synchrotron users have been largely successful at accessing travel funding to use the CLS.
The benefits of having a synchrotron in a smaller community also include easy access from the airport, affordable accommodation, and lower overall ancillary costs.
Has the presence of the CLS in Saskatoon strengthened science in that city and elsewhere in the Prairie region of Canada?
The CLS caters to approximately 1000 scientists from academia, government and industry per year, approximately a third of them from the Prairies.
The CLS helps to train and educate hundreds of graduate students per year, attracts some of the most talented scientists in the world to Canada, fosters collaborations between Canadian and local scientists and colleagues at facilities around the world, and has created technologically advanced jobs and unique scientific and technical expertise in our province and country.
The CLS also strengthens Canada’s and Saskatchewan’s international scientific reputation through publications in academic literature (more than 5000 papers to date), through hosting international scientific conferences, and by bringing media attention to scientific discoveries.
The CLS collaborates with a number of other initiatives in the Prairies including the Protein Supercluster, the National Research Council’s Aquatic and Crop Resource Development Research Centre, and the Global Institute for Food Security.
It is important that Canda maintains a reliable advanced light source for Canadian scientists to be able to access
Are there any plans to build complementary facilities in Saskatoon? For example, a neutron source that would make Saskatoon the “Grenoble of the Prairies”?
The University of Saskatchewan, the CLS’s owner, is a leader in the effort to build a new dedicated neutron source for Canada. It would be advantageous of course to have it near the CLS, in terms of the complementary nature of the research and the enormous possibilities for scientific cross-pollination, but there are no immediate plans to build a neutron source on our campus.
However, the proximity to the university – as well as the federal agriculture department, nuclear science facilities, and an innovation park renowned for its plant biotech companies – has created a cluster known for its global-leading agriculture expertise, which culminated in the recently funded Protein Industries Canada (PIC), an industry-led, not-for-profit organization created to position Canada as a global source of high-quality plant protein and plant-based co-products.
What will the future bring for the CLS? Are there any major upgrade plans?
The CLS is a third-generation facility and already brighter, faster and stronger fourth-generation light source facilities are being built around the world. While the CLS will remain globally competitive and a crucial resource for the Canadian scientific community for at least a decade, the national light source science community is developing plans for the next generation of Canadian synchrotron-enabled science.
Based on consultations with international machine-design experts as well as extensive engagement with the Canadian user community, a conceptual design report for CLS 2.0 is in development. CLS 2.0’s beam will be 700 times brighter and more coherent than the current CLS. A brighter, faster and smaller light beam will enable scientists to see samples much more clearly and collect better data much faster, allowing for better scientific outcomes.
CLS 2.0 will be among the best light sources in the world and will enable the Canadian scientific community to remain a global leader.
What are some of the physics research highlights from the CLS over the past 16 years?
Physics is the backbone of everything we do as a science facility – the accelerator and rings operate thanks to the expertise of our physicists and engineers – and it is a huge part of the research programme. Our Far-Infrared beamline, for example, is a powerful tool for studying molecular vibrational dynamics, as Ohio State University and University of New Brunswick scientists showed by demonstrating the effects of quantum monodromy on the spectrum of cyanogen is-thiocyanate.
Our many X-ray beamlines can be put to several useful applications in physics research, most prominently in the recent discovery and exploration of charge density waves in cuprate superconductors.
Vast expanses Inside the CLS experimental hall, which welcomes scientists from across Canada and beyond. (Courtesy: Canadian Light Source)
Recently, our REIXS beamline was used by the Canadian Space Agency and NASA scientists to test and validate the performance of window shielding for an upcoming satellite launch, by ensuring that X-rays within the desired range, but no infrared light, could pass through.
Researchers from University of Toronto and King Abdullah University of Science and Technology have overcome a key obstacle in combining the emerging solar-harvesting technology of perovskites with the commercial gold standard – silicon solar cells. The result is a highly efficient and stable tandem solar cell with the perovskites mixed as a liquid solar ink. The CLS was used to show that the solution processing treatment left the perovskites’ crystal structure untouched, leaving their basic function intact.
The REIXS beamline, one of the top X-ray scattering beamlines in the world in quantum materials research, was used to study a conductor-to-insulator phase change in samarium nickelate, a quantum material known as a strongly correlated electron system. The dramatic phase change means that the material can be used as a very sensitive detector. Indeed the team from the CLS, Argonne National Laboratory, Rutgers University, the National Institute of Standards and Technology, the Massachusetts Institute of Technology, Columbia University and the University of Massachusetts was inspired by an organ near a shark’s mouth called the ampullae of Lorenzini, which is capable of detecting small electric fields from prey animals.
This of course is just a small subsection of the physics research at our facility, which also covers hydrophobics, catalyst structure, new imaging techniques and many other areas.


physicsworld--2020-10-07--Roger Penrose discusses his career in mathematical physics - Physics World

Roger Penrose is one of the recipients of this year ’ s Nobel Prize for Physics .
The British mathematical physicist was honoured for his discovery that black hole formation is a robust prediction of the general theory of relativity .
In this interview with Physics World ’ s Tushna Commissariat , recorded in 2015 , Penrose looks back to the early years of his career as a PhD student at the University of Cambridge .
Penrose describes how he was inspired by courses given by eminent physicists including Paul Dirac and Hermann Bondi .
But his career-long interest in @ @ @ @ @ @ @ lecture by David Finkelstein on the nature of event horizons and the concept of a singularity .
Speaking at the ‘ Celebrating 100 Years of General Relativity ’ event at by Queen Mary University of London , Penrose also looks to the future of his field .
He believes that in the long-standing quest to unify the theories of gravity and quantum mechanics , it is quantum theory that must be modified significantly beyond its current form .
The ( now ) Nobel laureate refers to this process as the “ gravitization of @ @ @ @

Roger Penrose is one of the recipients of this year’s Nobel Prize for Physics. The British mathematical physicist was honoured for his discovery that black-hole formation is a robust prediction of the general theory of relativity.
In this interview with Physics World’s Tushna Commissariat, recorded in 2015, Penrose looks back to the early years of his career as a PhD student at the University of Cambridge. Penrose describes how he was inspired by courses given by eminent physicists including Paul Dirac and Hermann Bondi. But his career-long interest in black holes was triggered by attending a lecture by David Finkelstein on the nature of event horizons and the concept of a singularity.
Speaking at the “Celebrating 100 Years of General Relativity” event at Queen Mary University of London, Penrose also looks to the future of his field. He believes that in the long-standing quest to unify the theories of gravity and quantum mechanics, it is quantum theory that must be modified significantly beyond its current form. The (now) Nobel laureate refers to this process as the “gravitization of quantum mechanics”.


physicsworld--2020-10-08--Nanodiamond quantum thermometer measures the temperature of worms - Physics World

How do you take a worm ’ s temperature ?
With a quantum thermometer of course .
This is exactly what researchers have achieved using devices containing nanodiamonds with nitrogen-vacancy ( NV ) defect centres , the magnetic resonances of which change with temperature .
The new technique could be important for a range of clinical applications .
You may ask , why take the temperature of a worm ?
One of the reasons is that the temperature within a living organism is a direct measure of the biological activities happening inside .
Going down to the submicron-scale temperature range @ @ @ @ @ @ @ should provide detailed information on cellular and molecular activities .
This could be important for clinical applications such as imaging brain sub-tissue structures , visualizing tumour heterogeneity and mapping adipocytes , to cite just three examples .
It is , however , no easy task to reduce the size of biocompatible thermometers down to this small scale .
Recent years have the seen the emergence of light-emitting nanothermometers – such as thermoresponsive molecular probes and nanoparticles – that could overcome this technical limitation .
Most devices made thus far , however , are @ @ @ @ @ @ @ can only monitor temperature changes over relatively long periods ( hours ) .
They are also not completely biocompatible .
The nanodiamond quantum thermometers employed in the new study are promising in many respects .
The probes are made of nanodiamond , which naturally contains defects , known as NV centres .
These occur when two adjacent carbon atoms in a diamond lattice are replaced with a nitrogen atom and an empty lattice site .
The nitrogen has an extra electron that remains unpaired and so behaves as an isolated spin .
This @ @ @ @ @ @ @ “ down ” or in a superposition of the two .
Its state can be probed by illuminating the diamond with laser light and recording the intensity and frequencies of the emitted fluorescence .
NVs in nanodiamonds are ideal as biological probes because they are non-toxic , photostable , have surfaces that can be functionalized and can be easily inserted into living cells .
They are also isolated from their surroundings , which means that their quantum behaviour is not immediately affected by surrounding thermal fluctuations , and can detect the very weak @ @ @ @ @ @ @ or nuclear spins .
They can thus be used as highly-sensitive magnetic resonance probes capable of monitoring local spin changes in a material over distances of a few tens of nanometres .
And , in contrast to conventional magnetic resonance imaging ( MRI ) techniques in biology , in which millions of spins are required to produce a measurable signal , the NV defects can detect individual target spins with nanoscale spatial precision .
In their experiments , Masazumi Fujiwara of Osaka City University in Japan and colleagues functionalized the surfaces of the @ @ @ @ @ @ @ into C. elegans nematode worms ( one of the most popular animal models in biology ) .
The sensor began by reading the base “ healthy ” temperature of the creatures as a frequency shift of the optically detected magnetic resonance of the NV defect centres .
Since the nanodiamonds move much more quickly inside a worm than in cultured cells , the researchers developed a fast particle-tracking algorithm .
They also included an error-correction filter that takes into account the worm ’ s body structure , which can cause substantial fluctuations in @ @ @ @ @ @ @ and can create temperature-measurement artefacts .
Next , the team , who report their work in Science Advances , induced an artificial “ fever ” in the worms by stimulating their mitochondria with a chemical .
Their sensor successfully recorded this temperature increase with a precision of around ±0.22°C .
“ It was fascinating to see quantum technology work so well in live animals and I never imagined that the temperatures of tiny worms less than 1 mm in size could deviate from the norm and develop into a fever , ” says @ @ @ @ @ @ @ important milestone that will guide the future direction of quantum sensing as it shows how it contributes to biology .
”

Researchers measured the temperature of C. elegans nematode worms via tracking of embedded nanodiamonds. (Courtesy: Masazumi Fujiwara, Osaka City University)
How do you take a worm’s temperature? With a quantum thermometer of course. This is exactly what researchers have achieved using devices containing nanodiamonds with nitrogen-vacancy (NV) defect centres, the magnetic resonances of which change with temperature. The new technique could be important for a range of clinical applications.
You may ask, why take the temperature of a worm? One of the reasons is that the temperature within a living organism is a direct measure of the biological activities happening inside. Going down to the submicron-scale temperature range, as in this new work, should provide detailed information on cellular and molecular activities. This could be important for clinical applications such as imaging brain sub-tissue structures, visualizing tumour heterogeneity and mapping adipocytes, to cite just three examples. It is, however, no easy task to reduce the size of biocompatible thermometers down to this small scale.
Recent years have the seen the emergence of light-emitting nanothermometers – such as thermoresponsive molecular probes and nanoparticles – that could overcome this technical limitation. Most devices made thus far, however, are not robust enough for long-term use and can only monitor temperature changes over relatively long periods (hours). They are also not completely biocompatible.
Nanodiamond quantum thermometers
The nanodiamond quantum thermometers employed in the new study are promising in many respects. The probes are made of nanodiamond, which naturally contains defects, known as NV centres. These occur when two adjacent carbon atoms in a diamond lattice are replaced with a nitrogen atom and an empty lattice site.
The nitrogen has an extra electron that remains unpaired and so behaves as an isolated spin. This spin can be “up” or “down” or in a superposition of the two. Its state can be probed by illuminating the diamond with laser light and recording the intensity and frequencies of the emitted fluorescence.
NVs in nanodiamonds are ideal as biological probes because they are non-toxic, photostable, have surfaces that can be functionalized and can be easily inserted into living cells. They are also isolated from their surroundings, which means that their quantum behaviour is not immediately affected by surrounding thermal fluctuations, and can detect the very weak magnetic fields that come from nearby electronic or nuclear spins. They can thus be used as highly-sensitive magnetic resonance probes capable of monitoring local spin changes in a material over distances of a few tens of nanometres. And, in contrast to conventional magnetic resonance imaging (MRI) techniques in biology, in which millions of spins are required to produce a measurable signal, the NV defects can detect individual target spins with nanoscale spatial precision.
Healthy worms vs worms with a fever
In their experiments, Masazumi Fujiwara of Osaka City University in Japan and colleagues functionalized the surfaces of the nanodiamonds with polymer structures and injected them into C. elegans nematode worms (one of the most popular animal models in biology). The sensor began by reading the base “healthy” temperature of the creatures as a frequency shift of the optically detected magnetic resonance of the NV defect centres.
Since the nanodiamonds move much more quickly inside a worm than in cultured cells, the researchers developed a fast particle-tracking algorithm. They also included an error-correction filter that takes into account the worm’s body structure, which can cause substantial fluctuations in the intensity of the fluorescent light emitted and can create temperature-measurement artefacts.
Next, the team, who report their work in Science Advances, induced an artificial “fever” in the worms by stimulating their mitochondria with a chemical. Their sensor successfully recorded this temperature increase with a precision of around ±0.22°C.
“It was fascinating to see quantum technology work so well in live animals and I never imagined that the temperatures of tiny worms less than 1 mm in size could deviate from the norm and develop into a fever,” says Fujiwara. “Our results are an important milestone that will guide the future direction of quantum sensing as it shows how it contributes to biology.”


physicsworld--2020-10-08--Net-zero carbon target in UK will require national approach to materials science, says report - Phys

Net-zero carbon target in UK will require national approach to materials science, says report - Physics World

A national co-ordinated approach to material science in the UK is needed to meet the country ’ s 2050 net-zero carbon targets .
That is according to the Henry Royce Institute , which has released five roadmaps detailing how materials science and engineering can contribute to this energy transition .
Funded by the Engineering & Physical Sciences Research Council , the Henry Royce Institute is the UK ’ s national centre for advanced materials research and innovation .
It is a partnership between six UK universities as well as the National Nuclear Laboratory and the United Kingdom Atomic Energy Authority @ @ @ @ @ @ @ of a series of workshops held earlier this year , in which more than 200 material scientists were brought together by the Henry Royce Institute and the Institute of Physics , which publishes Physics World .
They explored the role of materials in meeting the UK ’ s target of bringing all greenhouse-gas emissions to net zero by 2050 , which the UK passed into law last year .
The roadmaps cover materials for photovoltaic systems , low-carbon generation of hydrogen , thermoelectric energy conversion , caloric energy conversion and low-loss electronics .
@ @ @ @ @ @ @ in each area the UK will have to bring together the research community , industry and government to identify immediate and long-term requirements for the development of energy materials to replace fossil-fuel technologies .
“ These important materials roadmaps demonstrate , in detail , how cutting-edge materials science and engineering will play a key role this major energy transition , ” says Julia King , chair of the Henry Royce Institute and a former chief executive of the IOP .
“ Novel materials will be essential to deliver the disruptive technologies that will @ @ @ @ @ @ @ we urgently need.
” Oliver Fenwick , a material scientist at Queen Mary University of London who led the thermoelectric energy conversion theme , says that the development of new or improved materials underpins most emerging technologies .
“ The transition to net-zero emissions presents significant opportunities for new materials , and this is particularly the case for thermoelectric technology , ” he says .
“ The challenge is significant , but the opportunity for the UK in this sector is huge , with 17 % of our CO emissions coming from space @ @ @ @ @ @ @ Institute calls for new national facilities to test technologies and ease their transfer from laboratories to prototypes .
It also says the UK government must invest in the material-science skills base and encourage or legislate the use of low-carbon technology .
King adds that many of these next generation materials are already showing great potential .
“ Our challenge is to deploy them at scale , ” she says .
“ We now need to have a meaningful dialogue with our government partners to agree on what is technically feasible and economically viable @ @

Going green: the new roadmaps cover materials for photovoltaic systems, low-carbon generation of hydrogen, thermoelectric energy conversion, caloric energy conversion and low-loss electronics (Courtesy: Shutterstock/hrui)
A national co-ordinated approach to material science in the UK is needed to meet the country’s 2050 net-zero carbon targets. That is according to the Henry Royce Institute, which has released five roadmaps detailing how materials science and engineering can contribute to this energy transition.
Funded by the Engineering & Physical Sciences Research Council, the Henry Royce Institute is the UK’s national centre for advanced materials research and innovation. It is a partnership between six UK universities as well as the National Nuclear Laboratory and the United Kingdom Atomic Energy Authority.
The new roadmaps are the result of a series of workshops held earlier this year, in which more than 200 material scientists were brought together by the Henry Royce Institute and the Institute of Physics (IOP), which publishes Physics World. They explored the role of materials in meeting the UK’s target of bringing all greenhouse-gas emissions to net zero by 2050, which the UK passed into law last year.
The roadmaps cover materials for photovoltaic systems, low-carbon generation of hydrogen, thermoelectric energy conversion, caloric energy conversion and low-loss electronics. According to the Henry Royce Institute, in each area the UK will have to bring together the research community, industry and government to identify immediate and long-term requirements for the development of energy materials to replace fossil-fuel technologies.
“These important materials roadmaps demonstrate, in detail, how cutting-edge materials science and engineering will play a key role this major energy transition,” says Julia King, chair of the Henry Royce Institute and a former chief executive of the IOP. “Novel materials will be essential to deliver the disruptive technologies that will bring about the energy-efficient applications and processes we urgently need.”
Showing potential
Oliver Fenwick, a material scientist at Queen Mary University of London who led the thermoelectric energy conversion theme, says that the development of new or improved materials underpins most emerging technologies. “The transition to net-zero emissions presents significant opportunities for new materials, and this is particularly the case for thermoelectric technology,” he says. “The challenge is significant, but the opportunity for the UK in this sector is huge, with 17% of our CO 2 emissions coming from space heating and cooling.”
The Henry Royce Institute calls for new national facilities to test technologies and ease their transfer from laboratories to prototypes. It also says the UK government must invest in the material-science skills base and encourage or legislate the use of low-carbon technology.
King adds that many of these next generation materials are already showing great potential. “Our challenge is to deploy them at scale,” she says. “We now need to have a meaningful dialogue with our government partners to agree on what is technically feasible and economically viable.”


physicsworld--2020-10-08--Tiny ingestible capsule helps treat gastrointestinal disorders - Physics World

Researchers in the US , Denmark and Sweden have designed a novel microstimulation device that can attach to the gastrointestinal ( GI ) tract and electrically stimulate the stomach muscles to induce contractions .
The new device , described in Science Advances , aims to treat disorders such as gastroparesis , which prevents the stomach from properly emptying .
Decades of scientific and medical research has shown that , due to the presence of neural circuits in the GI tract , electrical impulses that stimulate nerves and muscles can improve the health and quality-of-life of patients with GI-related disorders .
@ @ @ @ @ @ @ the common approach has been surgical implantation of gastric pacemakers that stimulate the outer muscular layer of the stomach .
To reduce cost barriers and address safety concerns associated with surgical implantations , recent developments in orally-administered therapies and ingestible robotic systems could prove of paramount importance .
Yet currently available robotic sensors can not provide electrical microstimulation in a controlled manner .
Therefore , there is a clear need for oral electrical stimulation systems that can be employed on an as-needed basis .
To overcome issues related to sensor control , management @ @ @ @ @ @ @ at Massachusetts Institute of Technology , in collaboration with researchers at Novo Nordisk and KTH Royal Institute of Technology , have developed an orally administered electrical stimulation device .
The design of the new device was inspired by the way that a parasitic worm , the Taenia solium tapeworm , uses hooks to attach to the GI tract of its host .
Between five and 15 minutes after the device is ingested , it autonomously aligns itself with the curved stomach lining and uses a compressed spring to insert tiny hooked stainless steel @ @ @ @ @ @ @ The needles act as probes to provide timed electrical pulses , thereby improving the device ’ s controllability .
The electrical pulses can conductively signal the probe ’ s anchoring and detachment events and thus allow the device to communicate its position .
Abramson and the team tested the new sensor in ex vivo human stomach tissues and in vivo in pig stomachs .
In sedated pigs , the device remained in place for up to two hours after being swallowed and repositioning itself along the stomach lining .
Whilst in place , @ @ @ @ @ @ @ the tissue .
The researchers also applied the device in awake pigs .
The devices were orally ingested by pigs with empty stomachs , and then – as designed – the sensors naturally detached after the pigs ate and digested their food .
In the absence of digestion , by localizing to a single spot on the tissue , the device can perform electrical microstimulations for an extended period of time .
“ The STIMS [ self-orienting technology for injection and electrical micro-stimulation ] capacity for tissue wall anchoring and signalling could enable @ @ @ @ @ @ @ on the tissue rather than the ambient environment , ” the authors write .

The STIMS capsule attaches to stomach lining and electrically stimulates muscle contractions. (Courtesy: Alex Abramson)
Researchers in the US, Denmark and Sweden have designed a novel microstimulation device that can attach to the gastrointestinal (GI) tract and electrically stimulate the stomach muscles to induce contractions. The new device, described in Science Advances, aims to treat disorders such as gastroparesis, which prevents the stomach from properly emptying.
Decades of scientific and medical research has shown that, due to the presence of neural circuits in the GI tract, electrical impulses that stimulate nerves and muscles can improve the health and quality-of-life of patients with GI-related disorders. For instance, to treat gastroparesis, the common approach has been surgical implantation of gastric pacemakers that stimulate the outer muscular layer of the stomach.
To reduce cost barriers and address safety concerns associated with surgical implantations, recent developments in orally administered therapies and ingestible robotic systems could prove of paramount importance. Yet currently available robotic sensors cannot provide electrical microstimulation in a controlled manner. Therefore, there is a clear need for oral electrical stimulation systems that can be employed on an as-needed basis.
First author Alex Abramson.
To overcome issues related to sensor control, management and communication, Alex Abramson and colleagues at Massachusetts Institute of Technology, in collaboration with researchers at Novo Nordisk and KTH Royal Institute of Technology, have developed an orally administered electrical stimulation device.
The design of the new device was inspired by the way that a parasitic worm, the Taenia solium tapeworm, uses hooks to attach to the GI tract of its host. Between five and 15 minutes after the device is ingested, it autonomously aligns itself with the curved stomach lining and uses a compressed spring to insert tiny hooked stainless steel needles i nto the stomach muscle wall. The needles act as probes to provide timed electrical pulses, thereby improving the device’s controllability.
Capsule schematic and working principle. (Courtesy: Alex Abramson)
The electrical pulses can conductively signal the probe’s anchoring and detachment events and thus allow the device to communicate its position. Abramson and the team tested the new sensor in ex vivo human stomach tissues and in vivo in pig stomachs. In sedated pigs, the device remained in place for up to two hours after being swallowed and repositioning itself along the stomach lining. Whilst in place, the device induced timed muscle contractions across the tissue.
The researchers also applied the device in awake pigs. The devices were orally ingested by pigs with empty stomachs, and then – as designed – the sensors naturally detached after the pigs ate and digested their food. In the absence of digestion, by localizing to a single spot on the tissue, the device can perform electrical microstimulations for an extended period of time.
“The STIMS [self-orienting technology for injection and electrical micro-stimulation] capacity for tissue wall anchoring and signalling could enable new applications for ingestible devices that focus on the tissue rather than the ambient environment,” the authors write.


physicsworld--2020-10-08--Smooth photonic waveguides keep propagation losses low - Physics World

Circuits that carry signals via visible and infrared light rather than electric currents are desirable for many applications because they transmit data faster and use less energy .
The problem is that current programmable photonic integrated circuits ( PICs ) are volatile and suffer from high optical signal losses – both of which prevent them from maintaining their programmed state .
A team of researchers in China has now succeeded in fabricating metre-scale single-mode waveguides that boast optical losses of only 0.03 dB/cm .
The researchers also used their waveguides to construct optical true delay lines ( OTDLs ) , @ @ @ @ @ @ @ devices – including future quantum information processors and sensors .
Current fabrication techniques for PICs produce devices with highly variable final properties .
This variability limits the techniques ’ yield and reduces the devices ’ configurability .
Existing techniques also produce devices with a high surface roughness , leading to high optical losses .
The excellent optical and electro-optical properties of lithium niobate on insulator ( LNOI ) offer a possible way around this problem .
The material has recently emerged as an attractive substrate material for PICs , and it shows promise @ @ @ @ @ @ @ higher density and greater tunability than previous devices .
However , while researchers had previously fabricated various photonic structures – including waveguides , microresonators and photonic crystal cavities – on LNOI , no group had succeeded in using it to fabricate high-quality , low-loss OTDLs .
A team of researchers led by Ya Cheng of East China Normal University has now done just that using a new technique called photolithography-associated chemo-mechanical etching ( PLACE ) .
The technique can produce smooth , metre-long waveguides on the LNOI that can be integrated with micro-electrodes @ @ @ @ @ @ @ tuned electro-optically at a later stage .
Cheng explains that PLACE requires five major steps .
The first step is to apply a thin coating of chromium of the top surface of lithium niobate thin film using a technique called magnetron sputtering .
Next , the researchers pattern the chromium film into a waveguide mask using space-selective femtosecond laser ablation .
They then use a chemo-mechanical polishing ( CMP ) process to selectively remove the lithium niobate .
The CMP process produces extremely smooth walls , leading to ultra-low light propagation losses in @ @ @ @ @ @ @ fifth steps involve removing the chromium mask layer using chemical wet etching and depositing a titanium oxide ( Ti O ) film on the fabrication lithium niobate waveguide as the cladding layer .
To measure the propagation losses in the OTDLs , the researchers used a high-precision loss measurement method that relies on comparing propagation losses in two waveguide arms of different lengths in a beamsplitter .
They used a wavelength-tuneable laser as the light source , tuning it to a wavelength of 1550 nm and coupling it into the waveguide through a @ @ @ @ @ @ @ light transmitted from the waveguide using a lens and then recorded its intensity with either a power meter or an infrared CCD .
The devices have propagation losses of just 0.03 dB/cm , meaning that after propagating in a one-metre long waveguide , half of the light power of the laser beam can be preserved , Cheng explains .
They are also reconfigurable thanks to the good electro-optical properties of lithium niobate .
The researchers , who report their work in Chinese Physics Letters , say they now hope to reduce propagation losses @ @ @ @ @ @ @ .
“ We will also be looking into applications for the OTDLs , probably beginning with quantum PICs , ” Cheng tells Physics World .

Lead author Junxia Zhou with the reported OTDL device. Courtesy: Junxia Zhou
Circuits that carry signals via visible and infrared light rather than electric currents are desirable for many applications because they transmit data faster and use less energy. The problem is that current programmable photonic integrated circuits (PICs) are volatile and suffer from high optical signal losses – both of which prevent them from maintaining their programmed state. A team of researchers in China has now succeeded in fabricating metre-scale single-mode waveguides that boast optical losses of only 0.03 dB/cm. The researchers also used their waveguides to construct optical true delay lines (OTDLs), which are important components of many photonic devices – including future quantum information processors and sensors.
Current fabrication techniques for PICs produce devices with highly variable final properties. This variability limits the techniques’ yield and reduces the devices’ configurability. Existing techniques also produce devices with a high surface roughness, leading to high optical losses.
The excellent optical and electro-optical properties of lithium niobate on insulator (LNOI) offer a possible way around this problem. The material has recently emerged as an attractive substrate material for PICs, and it shows promise for making circuits with lower losses, higher density and greater tunability than previous devices. However, while researchers had previously fabricated various photonic structures – including waveguides, microresonators and photonic crystal cavities – on LNOI, no group had succeeded in using it to fabricate high-quality, low-loss OTDLs.
Low-loss OTDLs on lithium niobate
A team of researchers led by Ya Cheng of East China Normal University has now done just that using a new technique called photolithography-associated chemo-mechanical etching (PLACE). The technique can produce smooth, metre-long waveguides on the LNOI that can be integrated with micro-electrodes, which allow the devices to be tuned electro-optically at a later stage.
Cheng explains that PLACE requires five major steps. The first step is to apply a thin coating of chromium of the top surface of lithium niobate thin film using a technique called magnetron sputtering. Next, the researchers pattern the chromium film into a waveguide mask using space-selective femtosecond laser ablation. They then use a chemo-mechanical polishing (CMP) process to selectively remove the lithium niobate. The CMP process produces extremely smooth walls, leading to ultralow light propagation losses in the finished waveguides. The fourth and fifth steps involve removing the chromium mask layer using chemical wet etching and depositing a titanium oxide (Ti 2 O 5 ) film on the fabrication lithium niobate waveguide as the cladding layer.
Ultra-low propagation losses
To measure the propagation losses in the OTDLs, the researchers used a high-precision loss measurement method that relies on comparing propagation losses in two waveguide arms of different lengths in a beamsplitter. They used a wavelength-tuneable laser as the light source, tuning it to a wavelength of 1550 nm and coupling it into the waveguide through a fibre taper. They first collected the light transmitted from the waveguide using a lens and then recorded its intensity with either a power meter or an infrared CCD.
The devices have propagation losses of just 0.03 dB/cm, meaning that after propagating in a one-metre long waveguide, half of the light power of the laser beam can be preserved, Cheng explains. They are also reconfigurable thanks to the good electro-optical properties of lithium niobate.
The researchers, who report their work in Chinese Physics Letters, say they now hope to reduce propagation losses even further by refining their fabrication technique. “We will also be looking into applications for the OTDLs, probably beginning with quantum PICs,” Cheng tells Physics World.