It’s possible that I shall make an ass of myself. But in that case one can always get out of it with a little dialectic. I have, of course, so worded my proposition as to be right either way (K.Marx, Letter to F.Engels on the Indian Mutiny)
Friday, April 30, 2021
Factors Associated With General Surgery Residents’ Operative Experience During the COVID-19 Pandemic
JAMA Surg. Published online April 30, 2021. doi:10.1001/jamasurg.2021.1978
Key Points
QuestionHow did general surgery resident operative volume change during the first 4 months of the US COVID-19 pandemic, and were all postgraduate year levels equally affected?
FindingsIn this review of 1358 resident case logs, general surgery resident operative volume declined by 33.5% in March to June 2020 compared with March to June 2018 and 2019 and affected residents in every level of training.
MeaningThese findings illustrate the significant negative effect of the COVID-19 pandemic on general surgery resident operative experience, highlighting the importance of identifying future mitigation strategies.
Abstract
ImportanceThe suspension of elective operations in March 2020 to prepare for the COVID-19 surge posed significant challenges to resident education. To mitigate the potential negative effects of COVID-19 on surgical education, it is important to quantify how the pandemic influenced resident operative volume.
ObjectiveTo examine the association of the pandemic with general surgical residents’ operative experience by postgraduate year (PGY) and case type and to evaluate if certain institutional characteristics were associated with a greater decline in surgical volume.
Design, Setting, and ParticipantsThis retrospective review included residents’ operative logs from 3 consecutive academic years (2017-2018, 2018-2019, and 2019-2020) from 16 general surgery programs. Data collected included total major cases, case type, and PGY. Faculty completed a survey about program demographics and COVID-19 response. Data on race were not collected. Operative volumes from March to June 2020 were compared with the same period during 2018 and 2019. Data were analyzed using Kruskal-Wallis test adjusted for within-program correlations.
Main Outcome and MeasuresTotal major cases performed by each resident during the first 4 months of the pandemic.
ResultsA total of 1368 case logs were analyzed. There was a 33.5% reduction in total major cases performed in March to June 2020 compared with 2018 and 2019 (45.0 [95% CI, 36.1-53.9] vs 67.7 [95% CI, 62.0-72.2]; P < .001), which significantly affected every PGY. All case types were significantly reduced in 2020 except liver, pancreas, small intestine, and trauma cases. There was a 10.2% reduction in operative volume during the 2019-2020 academic year compared with the 2 previous years (192.3 [95% CI, 178.5-206.1] vs 213.8 [95% CI, 203.6-223.9]; P < .001). Level 1 trauma centers (49.5 vs 68.5; 27.7%) had a significantly lower reduction in case volume than non–level 1 trauma centers (33.9 vs 63.0; 46%) (P = .03).
Conclusions and RelevanceIn this study of operative logs of general surgery residents in 16 US programs from 2017 to 2020, the first 4 months of the COVID-19 pandemic was associated with a significant reduction in operative experience, which affected every PGY and most case types. Level 1 trauma centers were less affected than non–level 1 centers. If this trend continues, the effect on surgical training may be even more detrimental.
IMAGE: REPRESENTATIVE IMAGES OF VASCULAR ENDOTHELIAL CONTROL CELLS (LEFT) AND CELLS TREATED WITH THE SARS-COV-2 SPIKE PROTEIN (RIGHT) SHOW THAT THE SPIKE PROTEIN CAUSES INCREASED MITOCHONDRIAL FRAGMENTATION IN VASCULAR CELLS.... view more
CREDIT: SALK INSTITUTE
LA JOLLA--(April 30, 2021) Scientists have known for a while that SARS-CoV-2's distinctive "spike" proteins help the virus infect its host by latching on to healthy cells. Now, a major new study shows that they also play a key role in the disease itself.
The paper, published on April 30, 2021, in Circulation Research, also shows conclusively that COVID-19 is a vascular disease, demonstrating exactly how the SARS-CoV-2 virus damages and attacks the vascular system on a cellular level. The findings help explain COVID-19's wide variety of seemingly unconnected complications, and could open the door for new research into more effective therapies.
"A lot of people think of it as a respiratory disease, but it's really a vascular disease," says Assistant Research Professor Uri Manor, who is co-senior author of the study. "That could explain why some people have strokes, and why some people have issues in other parts of the body. The commonality between them is that they all have vascular underpinnings."
Salk researchers collaborated with scientists at the University of California San Diego on the paper, including co-first author Jiao Zhang and co-senior author John Shyy, among others.
While the findings themselves aren't entirely a surprise, the paper provides clear confirmation and a detailed explanation of the mechanism through which the protein damages vascular cells for the first time. There's been a growing consensus that SARS-CoV-2 affects the vascular system, but exactly how it did so was not understood. Similarly, scientists studying other coronaviruses have long suspected that the spike protein contributed to damaging vascular endothelial cells, but this is the first time the process has been documented.
In the new study, the researchers created a "pseudovirus" that was surrounded by SARS-CoV-2 classic crown of spike proteins, but did not contain any actual virus. Exposure to this pseudovirus resulted in damage to the lungs and arteries of an animal model--proving that the spike protein alone was enough to cause disease. Tissue samples showed inflammation in endothelial cells lining the pulmonary artery walls.
The team then replicated this process in the lab, exposing healthy endothelial cells (which line arteries) to the spike protein. They showed that the spike protein damaged the cells by binding ACE2. This binding disrupted ACE2's molecular signaling to mitochondria (organelles that generate energy for cells), causing the mitochondria to become damaged and fragmented.
Previous studies have shown a similar effect when cells were exposed to the SARS-CoV-2 virus, but this is the first study to show that the damage occurs when cells are exposed to the spike protein on its own.
"If you remove the replicating capabilities of the virus, it still has a major damaging effect on the vascular cells, simply by virtue of its ability to bind to this ACE2 receptor, the S protein receptor, now famous thanks to COVID," Manor explains. "Further studies with mutant spike proteins will also provide new insight towards the infectivity and severity of mutant SARS CoV-2 viruses."
The researchers next hope to take a closer look at the mechanism by which the disrupted ACE2 protein damages mitochondria and causes them to change shape.
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Other authors on the study are Yuyang Lei and Zu-Yi Yuan of Jiaotong University in Xi'an, China; Cara R. Schiavon, Leonardo Andrade, and Gerald S. Shadel of Salk; Ming He, Hui Shen, Yichi Zhang, Yoshitake Cho, Mark Hepokoski, Jason X.-J. Yuan, Atul Malhotra, Jin Zhang of the University of California San Diego; Lili Chen, Qian Yin, Ting Lei, Hongliang Wang and Shengpeng Wang of Xi'an Jiatong University Health Science Center in Xi'an, China.
The research was supported by the National Institutes of Health, the National Natural Science Foundation of China, the Shaanxi Natural Science Fund, the National Key Research and Development Program, the First Affiliated Hospital of Xi'an Jiaotong University; and Xi'an Jiaotong University.
About the Salk Institute for Biological Studies:
Every cure has a starting point. The Salk Institute embodies Jonas Salk's mission to dare to make dreams into reality. Its internationally renowned and award-winning scientists explore the very foundations of life, seeking new understandings in neuroscience, genetics, immunology, plant biology and more. The Institute is an independent nonprofit organization and architectural landmark: small by choice, intimate by nature and fearless in the face of any challenge. Be it cancer or Alzheimer's, aging or diabetes, Salk is where cures begin. Learn more at: salk.edu.
Save the mother, save the child
Disrupting the cycle of intergenerational child abuse and neglect
IMAGE: 83% OF CHILD ABUSE ARE CHILDREN OF MOTHERS WITH A HISTORY OF CHILD PROTECTION CONTACT. view more
CREDIT: UNSPLASH
Supporting female survivors of childhood maltreatment is critical to disrupting intergenerational abuse as new research from the University of South Australia shows a clear link between parents who have suffered abuse and the likelihood of their children suffering the same fate.
The finding amplifies an acute need for far better support for victims of child maltreatment to ensure safer and more nurturing environments for all children.
Funded by the NHMRC and the Channel 7 Children's Research Foundation, and published in The Lancet Public Health today, the study found that most child maltreatment is occurring among families caught up in intergenerational cycles of child abuse and neglect - 83 per cent of the cases of substantiated child maltreatment were the children of mothers with a history of child protection contact.
The study showed that 30 per cent of the children of mothers with substantiated maltreatment as a child were also the subject of substantiated maltreatment (by age 12). In comparison, for children of mothers with no history of child protection contact, the rate of substantiated abuse was five per cent.
The study quantified the intergenerational transmission of child maltreatment in South Australia using a large linked data set from the internationally recognised iCAN study, which included 38,556 mother-child pairs - some of whom had experienced abuse and some who had not - based on SA child protection data.
The children of mothers exposed to substantiated maltreatment and removal into out-of-home care were at greatest risk of child maltreatment, with 14 times the risk of experiencing substantiated maltreatment, and 26 times the risk of being removed, reflecting extreme child protection concerns.
Lead Investigator, UniSA's Professor Leonie Segal, says the findings highlight the urgent need to do more to help these children and families - from early in life into adulthood - not just for their own well-being, but also as an intervention opportunity to protect their unborn children and future generations.
"The results are especially concerning given the generally poor outcomes for victims of child abuse or neglect across multiple health and social domains," Prof Segal says.
"Abused children often grow into adults with poor impulse control, a heightened sense of shame, an over-alertness to threat, easily triggered, with extreme levels of distress that can result in early substance use and mental illness, compounding harms.
"When these children become parents, their capacity for compassion or trust can be impaired, they often cannot see the needs of their own children, and can find it extremely difficult to provide the nurturing parenting that they would so want to offer.
"Our results are consistent with well-described biological mechanisms for intergenerational transmission of child maltreatment, through the lasting impacts of assault or neglect, altered brain development and disturbed relational patterning, strongly suggesting the observed associations are causal, and at least partly preventable.
"Children and parents need help. Healing their trauma is an ethical imperative, but also offers large health and economic payoffs to families and the wider community.
"The increased risk of child abuse and neglect among children whose mothers have experienced maltreatment themselves as children, is extreme and too significant to ignore - and they are already known to the service system.
"If only we could disrupt the intergenerational transmission pathway, we could prevent the lion's share of child maltreatment and turn around the life trajectories of our most vulnerable children and offer protection to future generations."
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Light as a fairy tale: What makes a feel-good film feel good?
First large-scale study of feel-good films and their audiences
IMAGE: FOR THE FIRST TIME, RESEARCHERS AT THE MAX PLANCK INSTITUTE FOR EMPIRICAL AESTHETICS HAVE SCIENTIFICALLY EXAMINED WHAT MAKES A FEEL-GOOD FILM FEEL GOOD. view more
CREDIT: MPI FOR EMPIRICAL AESTHETICS
"Feel-good films" are usually dismissed by film critics as being sentimental and without intellectual merit. But their popularity with audiences, who seek them out precisely because of their "feel-good" qualities, tells a more favorable story. Now, for the first time, this popular movie genre has been examined scientifically. A new study from the Max Planck Institute for Empirical Aesthetics investigates which feel-good films are considered by viewers to be prototypical and which factors constitute their feel-good effect.
"In addition to an element of humor and the classic happy ending, feel-good films can be identified by certain recurring plot patterns and characters," explains study leader and first author Keyvan Sarkhosh. "Often these involve outsiders in search of true love, who have to prove themselves and fight against adverse circumstances, and who eventually find their role in the community."
But feel-good films are characterized not just by romance and humor, but also by moments of drama, which usually have a strong emotional effect on viewers. At the same time, these features are often embedded in a fairy-tale setting, which is another typical aspect of the genre and contributes considerably to its perceived lightness. Not least, the mixture of all these elements can be considered constitutive of the feel-good film.
The results of this study have just been published in the journal Projections. The article emphasizes the fact that many people watch feel-good films specifically to relax and lift their spirits. Many of the study participants agreed that while feel-good films may be sentimental, they were not kitschy, and that above all they were technically well made. In this respect, the positive use of the genre label by viewers differs considerably from the predominantly negative perspective brought to it by professional film critics.
Original Publication:
Original Publication: Sarkhosh, K., und Menninghaus, W. (2021). The feel-good film: Genre features and emotional rewards. Projections, 15 (1), 55-92. DOI:10.3167/proj.2021.150104
CO2 catalysis made more accessible
An economical alloy-based aerogel as electrocatalyst for carbon fixation
Many industrial processes emit carbon dioxide into the atmosphere. Unfortunately, however, current electrochemical separation methods are expensive and consume large amounts of power. They also require expensive and rare metals as catalysts. A study in the journal Angewandte Chemie describes a new aerogel electrocatalyst formed from an inexpensive metal alloy, which enables highly efficient electrochemical conversion of carbon dioxide. The main product is formic acid, which is a nontoxic basic chemical.
Capturing and chemically fixing carbon dioxide from industrial processes would be a huge step towards carbon neutrality. To prevent the notorious greenhouse gas from escaping into the air, it can be compressed and stored. Another option is electrochemical conversion to give other carbon compounds.
However, due to high power consumption and the cost of catalysts, electrochemical separation methods cannot be used on an industrial scale. This prompted Tianyi Ma of Swinburne University of Technology in Hawthorn, Australia, and colleagues to investigate replacement materials. The electrocatalysts currently used are made from precious metals such as platinum and rhenium. They catalyze electrochemical carbon fixation processes very efficiently, but they are also very expensive.
The authors discovered that the nonprecious metals tin and bismuth can form aerogels, which are incredibly light materials with particularly promising catalyst properties. Aerogels contain an ultraporous network that promotes electrolyte transport. They also offer up abundant sites where the electrochemical processes can take place.
To produce the aerogels, the team mixed a solution of bismuth and tin salts with a reducing agent and a stabilizer. Simply stirring this mixture led to a stable hydrogel of a bismuth-tin alloy after six hours at room temperature. A straightforward freeze-drying process produced the aerogel, formed of loosely interwoven and branched nanowires.
The authors found the bimetallic aerogel performed outstandingly well for carbon dioxide conversion. Compared to pure bismuth, pure tin, or the non-freeze-dried alloy, a significantly higher current density was observed. The conversion took place with an efficiency of 93%, which was at least as efficient, if not more so, than the standard materials currently used, indicating a low-waste process.
The process showed "excellent selectivity and stability for the production of formic acid under normal pressure at room temperature." The only byproducts were carbon monoxide and hydrogen formed in miniscule amounts. The authors explain that this selectivity and stability was a result of the energy conditions at the surface of the alloy. Here, the carbon dioxide molecules accumulate in such a way that the carbon atom is free to bind hydrogen atoms from water molecules. This gives formic acid as the favored product.
This research hints at positive future prospects for other combinations of metals. It is likely that other nonprecious metals would convert to aerogels, forming inexpensive, nontoxic, and highly efficient catalysts for electrochemical carbon dioxide reduction.
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About the Author
Dr. Tianyi Ma is an Associate Professor at the Faculty of Science, Engineering and Technology of Swinburne University of Technology, Hawthorn, Australia. He works on the rational design, synthesis, and characterization of nanostructured materials for energy and environment-related applications in catalysis, adsorption, and separation, as well as energy conversion and storage.
IMAGE: COGNITIVE MAPS IN THE BRAIN HELP US TO ACT ACCORDING TO A SPECIFIC SITUATION. view more
CREDIT: MPI CBS
Successful navigation requires the ability to separate memories in a context-dependent manner. For example, to find lost keys, one must first remember whether the keys were left in the kitchen or the office. How does the human brain retrieve the contextual memories that drive behavior? J.B. Julian of the Princeton Neuroscience Institute at Princeton University, USA, and Christian F. Doeller of the Max Planck Institute for Human Cognitive and Brain Sciences in Leipzig, Germany, found in a recent study that modulation of map-like representations in our brain's hippocampal formation can predict contextual memory retrieval in an ambiguous environment.
The researchers developed a novel virtual reality navigation task in which human participants learned object positions in two different virtual environments and then had their memory tested during a functional MRI scan. Memory for object locations was also tested in a third ambiguous context, which the researchers defined as a "squircle" - a cross between a square and a circle. There were no "correct" object positions there; instead, study participants had to rely solely on their memory. "The result of our study confirms the theory, long held by several neuroscientists, that a critical function of the hippocampal formation is to represent the contextual information that guides behavior. Cognitive maps in the brain help us to act according to a specific situation. ", explains Christian Doeller.
Although decades of research indicate that the human hippocampus is critical for contextual memory, no previous studies have linked context-specific signals in this formation of the brain to spatial behavior in a way that clearly separates memory from non-memory factors. This research was performed in collaboration with the Kavli Institute for Systems Neuroscience, NTNU, Trondheim, Norway and supported by the European Research Council (ERC-CoG GEOCOG).
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Original publication
Julian, J.B., Doeller, C.F. Remapping and realignment in the human hippocampal formation predict context-dependent spatial behavior. Nat Neurosci (2021) 15 April 2021
Disclaimer: AAAS and Eur
Research spotlights Minnesota's successes in eradicating Palmer amaranth
Palmer amaranth is a hard-to-control noxious weed that can significantly reduce crop yields.
WESTMINSTER, Colorado - April 30, 2021 - Palmer amaranth is a hard-to-control noxious weed that can significantly reduce crop yields. It was first introduced in Minnesota in 2016 through contaminated seed mixes used for conservation plantings.
Fortunately, Minnesota regulators were prepared. They had already declared Palmer amaranth a prohibited noxious weed in 2015, and they quickly added the weed's seed to their prohibited list by emergency order. As a result, they were able to take prompt action to identify and eradicate newly emerged infestations.
A research paper featured in the journal Weed Technology documents Minnesota's experiences, including the timeline to eradication, best practices and lessons learned.
Of the sites sown with contaminated seed mixes, Palmer amaranth was found at eight. With intensive scouting, torching, prescribed burning and herbicide application in 2016 and 2017, those infestations were eradicated. Similar results were achieved in 2018, 2019 and 2020 when populations of Palmer amaranth were discovered at new locations across the state.
The authors point to several success factors, including broad cooperation among the commissioner of agriculture, legislative committees, commodity groups and farmers. Once an aggressive protocol to address Palmer amaranth was established, critical information could be quickly disseminated across the agricultural community and to the public. One example: When officials determined that manure from livestock could contain viable Palmer amaranth seeds, they were able to quickly share the information with growers and take steps to eliminate the risk.
"Establishing the appropriate regulatory framework, providing funding, fostering collaboration among partners and actively responding to new infestations have been critical to Minnesota's success of combatting Palmer amaranth," says Eric Yu, plant health specialist with the Minnesota Department of Agriculture.
Yu cautions, though, that lasting success will depend on regional cooperation among states to manage infestations and to address the many pathways that can contribute to Palmer amaranth's spread.
Weed Technology is a journal of the Weed Science Society of America, a nonprofit scientific society focused on weeds and their impact on the environment. The publication presents original research and special articles about weeds, crops and new technologies used for more effective weed management. To learn more, visit http://www.wssa.net.
Not just for finding planets: Exoplanet-hunter TESS telescope spots bright gamma-ray burst
IMAGE: TESS FULL-FRAME IMAGE IN THE CADENCE JUST BEFORE THE BAT TRIGGER (LEFT) AND AT THE PEAK FLUX OF THE BURST (CENTER). THE EMERGENCE OF THE AFTERGLOW IS APPARENT IN THE... view more
CREDIT: THE ASTROPHYSICAL JOURNAL
DALLAS (SMU) - NASA has a long tradition of unexpected discoveries, and the space program's TESS mission is no different. SMU astrophysicist and her team have discovered a particularly bright gamma-ray burst using a NASA telescope designed to find exoplanets - those occurring outside our solar system - particularly those that might be able to support life.
It's the first time a gamma-ray burst has been found this way.
Gamma-ray bursts are the brightest explosions in the universe, typically associated with the collapse of a massive star and the birth of a black hole. They can produce as much radioactive energy as the sun will release during its entire 10-billion-year existence.
Krista Lynne Smith, an assistant professor of physics at Southern Methodist University, and her team confirmed the blast - called GRB 191016A - happened on Oct. 16 and also determined its location and duration. A study on the discovery has been published in The Astrophysical Journal.
"Our findings prove this TESS telescope is useful not just for finding new planets, but also for high-energy astrophysics," said Smith, who specializes in using satellites like TESS (Transiting Exoplanet Survey Satellite) to study supermassive black holes and gas that surrounds them. Such studies shed light on the behavior of matter in the deeply warped spacetime around black holes and the processes by which black holes emit powerful jets into their host galaxies.
Smith calculated that GRB 191016A had a peak magnitude of 15.1, which means it was 10,000 times fainter than the faintest stars we can see with the naked eyes.
That may sound quite dim, but the faintness has to do with how far away the burst occurred. It is estimated that light from GRB 191016A's galaxy had been travelling 11.7 billion years before becoming visible in the TESS telescope.
Most gamma ray bursts are dimmer - closer to 160,000 times fainter than the faintest stars.
The burst reached its peak brightness sometime between 1,000 and 2,600 seconds, then faded gradually until it fell below the ability of TESS to detect it some 7000 seconds after it first went off.
This gamma-ray burst was first detected by a NASA's satellite called Swift-BAT, which was built to find these bursts. But because GRB 191016A occurred too close to the moon, the Swift-BAT couldn't do the necessary follow-up it normally would have to learn more about it until hours later.
NASA's TESS happened to be looking at that same part of the sky. That was sheer luck, as TESS turns its attention to a new strip of the sky every month.
While exoplanet researchers at a ground-base for TESS could tell right away that a gamma-ray burst had happened, it would be months before they got any data from the TESS satellite on it. But since their focus was on new planets, these researchers asked if any other scientists at a TESS conference in Sydney, Australia were interested in doing more digging on the blast.
Smith was one of the few high-energy astrophysics specialists there at that time and quickly volunteered.
"The TESS satellite has a lot of potential for high-energy applications, and this was too good an example to pass up," she said. High-energy astrophysics studies the behavior of matter and energy in extreme environments, including the regions around black holes, powerful relativistic jets, and explosions like gamma-ray bursts.
TESS is an optical telescope that collects light curves on everything in its field of view, every half hour. Light curves are a graph of light intensity of a celestial object or region as a function of time. Smith analyzed three of these light curves to be able to determine how bright the burst was.
She also used data from ground-based observatories and the Swift gamma-ray satellite to determine the burst's distance and other qualities about it.
"Because the burst reached its peak brightness later and had a peak brightness that was higher than most bursts, it allowed the TESS telescope to make multiple observations before the burst faded below the telescope's detection limit," Smith said. "We've provided the only space-based optical follow-up on this exceptional burst."
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About SMU
SMU is the nationally ranked global research university in the dynamic city of Dallas. SMU's alumni, faculty and nearly 12,000 students in eight degree-granting schools demonstrate an entrepreneurial spirit as they lead change in their professions, communities and the world.
World's first fiber-optic ultrasonic imaging probe for future nanoscale disease diagnostics
IMAGE: CONCEPT ART SHOWING THE 3D MAPPING OF MICROSCOPIC OBJECTS BY THE PHONON PROBE SYSTEM. THE OPTICAL FIBRE CONTAINS A METAL LAYER ON ITS TIP AND PROJECTS RED LASER LIGHT INTO... view more
CREDIT: DR SALVATORE LA CAVERA
Scientists at the University of Nottingham have developed an ultrasonic imaging system, which can be deployed on the tip of a hair-thin optical fibre, and will be insertable into the human body to visualise cell abnormalities in 3D.
The new technology produces microscopic and nanoscopic resolution images that will one day help clinicians to examine cells inhabiting hard-to-reach parts of the body, such as the gastrointestinal tract, and offer more effective diagnoses for diseases ranging from gastric cancer to bacterial meningitis.
The high level of performance the technology delivers is currently only possible in state-of-the-art research labs with large, scientific instruments - whereas this compact system has the potential to bring it into clinical settings to improve patient care.
The Engineering and Physical Sciences Research Council (EPSRC)-funded innovation also reduces the need for conventional fluorescent labels - chemicals used to examine cell biology under a microscope - which can be harmful to human cells in large doses.
The findings are being reported in a new paper, entitled 'Phonon imaging in 3D with a fibre probe' published in the Nature journal, Light: Science & Applications.
Paper author, Salvatore La Cavera, an EPSRC Doctoral Prize Fellow from the University of Nottingham Optics and Photonics Research Group, said of the ultrasonic imaging system: "We believe its ability to measure the stiffness of a specimen, its bio-compatibility, and its endoscopic-potential, all while accessing the nanoscale, are what set it apart. These features set the technology up for future measurements inside the body; towards the ultimate goal of minimally invasive point-of-care diagnostics."
Currently at prototype stage, the non-invasive imaging tool, described by the researchers as a "phonon probe", is capable of being inserted into a standard optical endoscope, which is a thin tube with a powerful light and camera at the end that is navigated into the body to find, analyse, and operate on cancerous lesions, among many other diseases. Combining optical and phonon technologies could be advantageous; speeding up the clinical workflow process and reducing the number of invasive test procedures for patients.
3D mapping capabilities
Just as a physician might conduct a physical examination to feel for abnormal 'stiffness' in tissue under the skin that could indicate tumours, the phonon probe will take this '3D mapping' concept to a cellular level.
By scanning the ultrasonic probe in space, it can reproduce a three-dimensional map of stiffness and spatial features of microscopic structures at, and below, the surface of a specimen (e.g. tissue); it does this with the power to image small objects like a large-scale microscope, and the contrast to differentiate objects like an ultrasonic probe.
"Techniques capable of measuring if a tumour cell is stiff have been realised with laboratory microscopes, but these powerful tools are cumbersome, immobile, and unadaptable to patient-facing clinical settings. Nanoscale ultrasonic technology in an endoscopic capacity is poised to make that leap," adds Salvatore La Cavera.
CAPTION
The optical fibre imaging sensor has a diameter of 125 micrometres, approximately the size a human hair, shown for perspective against a penny. A microscope image shows the true scale of the device, and its ability to conduct light.
CREDIT
Dr Salvatore La Cavera
How it works
The new ultrasonic imaging system uses two lasers that emit short pulses of energy to stimulate and detect vibrations in a specimen. One of the laser pulses is absorbed by a layer of metal - a nano-transducer (which works by converting energy from one form to another) - fabricated on the tip of the fibre; a process which results in high-frequency phonons (sound particles) getting pumped into the specimen. Then a second laser pulse collides with the sound waves, a process known as Brillouin scattering. By detecting these "collided" laser pulses, the shape of the travelling sound wave can be recreated and displayed visually.
The detected sound wave encodes information about the stiffness of a material, and even its geometry. The Nottingham team was the first to demonstrate this dual-capability using pulsed lasers and optical fibres.
The power of an imaging device is typically measured by the smallest object that can be seen by the system, i.e. the resolution. In two dimensions the phonon probe can "resolve" objects on the order of 1 micrometre, similar to a microscope; but in the third dimension (height) it provides measurements on the scale of nanometres, which is unprecedented for a fibre-optic imaging system.
Future applications
In the paper, the researchers demonstrate that the technology is compatible with both a single optical fibre and the 10-20,000 fibres of an imaging bundle (1mm in diameter), as used in conventional endoscopes.
Consequently, superior spatial resolution and wide fields of view could routinely be achieved by collecting stiffness and spatial information from multiple different points on a sample, without needing to move the device - bringing a new class of phonon endoscopes within reach.
Beyond clinical healthcare, fields such as precision manufacturing and metrology could use this high-resolution tool for surface inspections and material characterisation; a complementary or replacement measurement for existing scientific instruments. Burgeoning technologies such as 3D bio-printing and tissue engineering could also use the phonon probe as an inline inspection tool by integrating it directly to the outer diameter of the print-needle.
Next, the team will be developing a series of biological cell and tissue imaging applications in collaboration with the Nottingham Digestive Diseases Centre and the Institute of Biophysics, Imaging and Optical Science at the University of Nottingham; with the aim to create a viable clinical tool in the coming years.
CAPTION
(top) Conventional microscope pictures of model biological cells. (bottom) The phonon probe reproduces 3D images of the objects (colour is height). Simultaneously, the probe detected stiffness related measurements which are mapped in green on the top left image. The white scales bar are 10 micrometres long.
The University of Nottingham is a research-intensive university with a proud heritage, consistently ranked among the world's top 100. Studying at the University of Nottingham is a life-changing experience and we pride ourselves on unlocking the potential of our students. We have a pioneering spirit, expressed in the vision of our founder Sir Jesse Boot, which has seen us lead the way in establishing campuses in China and Malaysia - part of a globally connected network of education, research and industrial engagement. The University's state-of-the-art facilities and inclusive and disability sport provision is reflected in its status as The Times and Sunday Times Good University Guide 2021 Sports University of the Year. We are ranked eighth for research power in the UK according to REF 2014. We have six beacons of research excellence helping to transform lives and change the world; we are also a major employer and industry partner - locally and globally. Alongside Nottingham Trent University, we lead the Universities for Nottingham initiative, a pioneering collaboration which brings together the combined strength and civic missions of Nottingham's two world-class universities and is working with local communities and partners to aid recovery and renewal following the COVID-19 pandemic.