physicsworld--2020-10-26--On the road less travelled: a Black physicist’s journey in academia - Physics World

This past May I earned my doctorate in physics , becoming the first Black woman to do so at Yale University .
There are very few Black women with doctorates in physics .
Approximately 100 Black women have received a PhD in a physics-related field in the US .
With such a dearth in numbers , at times I experience a sense of loneliness and isolation in physics .
Some people are taken aback by my presence in research settings .
On a number of occasions , I have been mistaken for janitorial staff in physics departments , in national @ @ @ @ @ @ @ a common experience among my Black physics colleagues .
Anecdotally , the anonymity of e-mail and conference calls smooths over some of the stilted behaviour I otherwise experience working with new colleagues face-to-face .
An initial encounter may be awkward , but in time , as new colleagues become familiar with my physics acumen , preconceived notions fade away .
Physicists hail from all socioeconomic and cultural backgrounds .
I have had the good fortune of working closely with physicists from all over the world .
When we rally around the physics questions @ @ @ @ @ @ @ ’ t seem to matter .
Close collaboration in physics requires trust , openness and transparency .
With these keystones to a relationship established in the physics setting , the pivot to get to know and understand my colleagues on a more personal level is eased .
Even though making a groundbreaking measurement or establishing a revolutionary new theory is ultimately what many of us are after as researchers , close relationships developed along our journeys are the sustenance that keeps us going .
As an undergraduate studying physics at Princeton University , @ @ @ @ @ @ @ with Frank Calaprice .
The experience fundamentally changed the trajectory of my life .
But for this connection , I would not be in the position I find myself in today .
As my senior thesis adviser , Calaprice suggested a topic , in situ purification for liquid-argon dark-matter detectors , that I could actively work on in the laboratory over the course of my senior year .
Apparently pleased with my work , Calaprice offered me a position to continue working with him the summer following graduation .
I continued on with @ @ @ @ @ @ @ During that time , I worked closely with Princeton PhD students and postdoctoral associates , travelled internationally to work at Gran Sasso National Laboratory in Italy , and developed the confidence to pursue a doctorate in physics .
Years later , Princeton held a celebration for Calaprice marking his many contributions to the field .
Among the attendees were a physics Nobel laureate and many prominent professors of physics and national laboratory staff scientists .
Over the course of the event programme , I learned about the trials and tribulations Calaprice had encountered @ @ @ @ @ @ @ me most was the continued mentorship he had carried out over the years .
There were many people just like me whom Calaprice had taken under his wing and worked closely with in their development as scientists .
These mentees hailed from all backgrounds .
Our common denominator was our interest in physics .
We would all like to leave our mark on the field with a groundbreaking discovery , but in many ways each of us can leave the field better than we found it through the people we develop and the @ @ @ @ @ @ @ blessed with a Frank Calaprice in their life .
However , the fostering of a constructive environment like the one I found myself in can and should be replicated to help bring new people into the field , especially those who otherwise initially think they do not have a place in physics .
In my view , funding agencies should invest in making physics research opportunities available to the unconventional candidate – perhaps a student who returns to academia later in life , or a student who lacks a sterling academic record , @ @ @ @ @ @ @ young parent , and so on – to broaden the base of potential graduate school applicants .
Burgeoning young scientists can be found within this talent pool , including up-and-coming Black scientists .
The assumption that deciding to pursue a career in physics should occur during one ’ s undergraduate years is not necessarily well founded .
In my case , life experiences helped prompt my path toward physics .
Much has been written about the scarcity of Black people with undergraduate and doctoral degrees in physics .
It is encouraging that awareness @ @ @ @ @ @ @ and that many universities are constructing action plans to rectify the situation .
I believe mentorship and investment in people will aid in turning the tide on the flatlined numbers of Black students pursuing physics degrees .
Further , by our rallying around the physics , cultural walls and divisions can crumble .
We should embrace our common physics interests in order to work through and better understand our differences .
By the numbers , Black physicists today are trailblazers , in that few have tread our current path .
It ’ s @ @ @ @ @ @ @ way for people of all backgrounds to follow .

This article is the first in a series of essays written by Black physicists and co-published with Physics Today as part of #BlackInPhysics week, an event dedicated to celebrating Black physicists and their contributions to the scientific community, and to revealing a more complete picture of what a physicist looks like.
Trailblazer Brooke Russell is the first Black woman to receive a doctorate in physics from Yale University. (Courtesy: Brooke Russell)
This past May I earned my doctorate in physics, becoming the first Black woman to do so at Yale University. There are very few Black women with doctorates in physics. Approximately 100 Black women have received a PhD in a physics-related field in the US.
With such a dearth in numbers, at times I experience a sense of loneliness and isolation in physics. Some people are taken aback by my presence in research settings. On a number of occasions, I have been mistaken for janitorial staff in physics departments, in national laboratories and at conferences. This is a common experience among my Black physics colleagues. Anecdotally, the anonymity of e-mail and conference calls smooths over some of the stilted behaviour I otherwise experience working with new colleagues face-to-face. An initial encounter may be awkward, but in time, as new colleagues become familiar with my physics acumen, preconceived notions fade away.
Physicists hail from all socioeconomic and cultural backgrounds. I have had the good fortune of working closely with physicists from all over the world. When we rally around the physics questions at hand, differences in background don’t seem to matter. Close collaboration in physics requires trust, openness and transparency. With these keystones to a relationship established in the physics setting, the pivot to get to know and understand my colleagues on a more personal level is eased. Even though making a groundbreaking measurement or establishing a revolutionary new theory is ultimately what many of us are after as researchers, close relationships developed along our journeys are the sustenance that keeps us going.
A mentor’s impact
As an undergraduate studying physics at Princeton University, I had the great fortune of working with Frank Calaprice. The experience fundamentally changed the trajectory of my life. But for this connection, I would not be in the position I find myself in today. As my senior thesis adviser, Calaprice suggested a topic, in situ purification for liquid-argon dark-matter detectors, that I could actively work on in the laboratory over the course of my senior year. Apparently pleased with my work, Calaprice offered me a position to continue working with him the summer following graduation. I continued on with Calaprice for the next two-plus years. During that time, I worked closely with Princeton PhD students and postdoctoral associates, travelled internationally to work at Gran Sasso National Laboratory in Italy, and developed the confidence to pursue a doctorate in physics.
Funding agencies should invest in making physics research opportunities available to the unconventional candidate
Years later, Princeton held a celebration for Calaprice marking his many contributions to the field. Among the attendees were a physics Nobel laureate and many prominent professors of physics and national laboratory staff scientists. Over the course of the event programme, I learned about the trials and tribulations Calaprice had encountered over his decades-long career. What struck me most was the continued mentorship he had carried out over the years. There were many people just like me whom Calaprice had taken under his wing and worked closely with in their development as scientists. These mentees hailed from all backgrounds. Our common denominator was our interest in physics. We would all like to leave our mark on the field with a groundbreaking discovery, but in many ways each of us can leave the field better than we found it through the people we develop and the connections we make.
Not everyone is blessed with a Frank Calaprice in their life. However, the fostering of a constructive environment like the one I found myself in can and should be replicated to help bring new people into the field, especially those who otherwise initially think they do not have a place in physics. In my view, funding agencies should invest in making physics research opportunities available to the unconventional candidate – perhaps a student who returns to academia later in life, or a student who lacks a sterling academic record, or a military veteran, or a young parent, and so on – to broaden the base of potential graduate school applicants. Burgeoning young scientists can be found within this talent pool, including up-and-coming Black scientists. The assumption that deciding to pursue a career in physics should occur during one’s undergraduate years is not necessarily well founded. In my case, life experiences helped prompt my path toward physics.
Breaking down walls
Much has been written about the scarcity of Black people with undergraduate and doctoral degrees in physics. It is encouraging that awareness of the issue is becoming more prevalent and that many universities are constructing action plans to rectify the situation. I believe mentorship and investment in people will aid in turning the tide on the flatlined numbers of Black students pursuing physics degrees. Further, by our rallying around the physics, cultural walls and divisions can crumble. We should embrace our common physics interests in order to work through and better understand our differences. By the numbers, Black physicists today are trailblazers, in that few have tread our current path. It’s on all of us to clear the way for people of all backgrounds to follow.


physicsworld--2020-10-27--Achieving a healthy work–life balance as a graduate student - Physics World

As a PhD student in physics , I ’ ve learned that the work–life balance during your graduate career can look different from how it did in your undergraduate life .
Graduate school in physics is hard , and it ’ s extremely important to make sure that you ’ re giving yourself time to enjoy things outside of work to recharge yourself .
During the first few years this might be a little difficult with all the classes and , depending on your programme , research and service work .
I definitely struggled to balance everything .
But finding @ @ @ @ @ @ @ of doing work all the time can start to have negative effects on you .
Sometimes they ’ re tangible and sometimes they ’ re not .
Since stress affects people in different ways , it ’ s important to recognize what happens to you .
For me , during my first few years as a postgraduate student , I mostly felt like I was going through the motions .
I was extremely busy with classes and qualifying exams , and the workload started to take its toll on me .
I started @ @ @ @ @ @ @ get eight hours of sleep and feel like I got four .
Luckily , my fellowship at West Virginia University in the US required service work , and I found a volunteer opportunity coaching soccer ( football ) , which I really enjoy .
Growing up I had watched my brothers play soccer and had eventually started playing too .
I played throughout high school and into university until suffering an injury .
Through the network I created by coaching , I also began playing soccer again , something I hadn ’ t @ @ @ @ @ @ @ for yourself Even if classes and research seem to take up all of your time , sometimes you have to make time .
During my first few years of graduate school , I made a point of taking one day off a week when I didn ’ t do anything except what I wanted to , be it video games , hanging out with my family , or reading .
I also started asking my friends for help on homework if I was stuck .
When I struggled through problems alone , I @ @ @ @ @ @ @ like I didn ’ t belong in the field .
I found that I could better understand the material if I laid out the steps of the problems with my friends , which reduced my stress .
It ’ s astounding to look back at my work–life balance during my undergraduate career , when for a period of time I wasn ’ t sleeping or eating well .
Since then I ’ ve learned how my body reacts under too much stress and when I need to better balance my work and life @ @ @ @ @ @ @ and allowed me to re-centre myself , and that occurred because I started to understand who I was as a person .
Now I know that I ’ m balancing my work and life well when on my days off I ’ m not worrying about what I have to do during the week .
If I have to work on weekends ( for conferences , research and the like ) , then I take an equivalent amount of time off during the week .
This is a valuable bit of advice I @ @ @ @ @ @ @ Although this is easier to do once you ’ ve finished classes and have a little bit more flexibility with your schedule , it ’ s always an important strategy for preventing burnout .
It also makes me more productive , not less .
When I start to burn out , sometimes it feels like I am giving 100 % , but it ’ s only about 50 % of what I can do when I ’ m not burned out .
When to take a break Today my schedule is built around @ @ @ @ @ @ @ graduate school more like a 9-to-5 job , where I work only during specific hours .
I make time to work out every day , because it allows me to focus on myself .
My family is extremely important to me , and we are very close , so I try to talk with them almost every day , and once a week we play Dungeons and Dragons together remotely .
We grew up playing that together in person , so it ’ s great to continue the tradition .
After working , @ @ @ @ @ @ @ time every night reading , and I ’ ve recently found a lot of joy in cooking .
Pursuing the things that bring you joy outside of work will help you maintain your mental health .
Sometimes , though , even with a good work–life balance , you may find that you ’ re struggling to stay motivated .
At that point , it might be a good idea to take a break and step back from research , classes , and work things , kind of like a holiday .
You can @ @ @ @ @ @ @ out how it will affect your progress in your programme .
This happened to me about a year ago .
I went through something traumatic , and at the time I thought I was handling it fine .
But after conversations with my mentors , I realized I needed to take a total break .
Afterward it was like a huge weight was lifted off my shoulders , and I felt at peace and motivated to start up research again .
The trauma that I went through didn ’ t just disappear ; @ @ @ @ @ @ @ after my break , and it was the reason I ended up transferring from West Virginia to Syracuse University .
I struggled a lot with making the decision to transfer , but I realized it was ultimately the best decision for me .
Sometimes things just don ’ t work out in one area , and that ’ s okay .
Recognizing when I needed to take a break came hand in hand with evaluating my mental health .
There are certain signs for me – getting nauseous while eating or not being @ @ @ @ @ @ @ – that mean I am in dire need of a break .
If I can recognize the signs before I get to the point where I need a long break of a month or more , I can combat them by taking off just a few days to a week .
Taking a break might make you feel like you ’ re going to fall behind and not be able to catch up , but I promise that won ’ t happen .
You ’ ll feel revitalized and be more motivated to @ @ @

This article is the third in a series of essays written by Black physicists and co-published with Physics Today as part of #BlackInPhysics week, an event dedicated to celebrating Black physicists and their contributions to the scientific community, and to revealing a more complete picture of what a physicist looks like.
Preventing burnout Knowing when to take a break has made Amber Lenon more productive. (Courtesy: Amber Lenon)
As a PhD student in physics, I’ve learned that the work–life balance during your graduate career can look different from how it did in your undergraduate life. Graduate school in physics is hard, and it’s extremely important to make sure that you’re giving yourself time to enjoy things outside of work to recharge yourself.
During the first few years this might be a little difficult with all the classes and, depending on your programme, research and service work. I definitely struggled to balance everything. But finding a balance is critical because the stress of doing work all the time can start to have negative effects on you. Sometimes they’re tangible and sometimes they’re not.
Since stress affects people in different ways, it’s important to recognize what happens to you. For me, during my first few years as a postgraduate student, I mostly felt like I was going through the motions. I was extremely busy with classes and qualifying exams, and the workload started to take its toll on me. I started to sleep extremely poorly. I would get eight hours of sleep and feel like I got four.
Luckily, my fellowship at West Virginia University in the US required service work, and I found a volunteer opportunity coaching soccer (football), which I really enjoy. Growing up I had watched my brothers play soccer and had eventually started playing too. I played throughout high school and into university until suffering an injury. Through the network I created by coaching, I also began playing soccer again, something I hadn’t done in years.
Carving out time for yourself
Even if classes and research seem to take up all of your time, sometimes you have to make time. During my first few years of graduate school, I made a point of taking one day off a week when I didn’t do anything except what I wanted to, be it video games, hanging out with my family, or reading. I also started asking my friends for help on homework if I was stuck. When I struggled through problems alone, I would start to doubt myself and feel like I didn’t belong in the field. I found that I could better understand the material if I laid out the steps of the problems with my friends, which reduced my stress.
Team player The author (seated, third from left) started coaching and playing soccer during her studies at West Virginia University in the US. (Courtesy: Amber Lenon)
It’s astounding to look back at my work–life balance during my undergraduate career, when for a period of time I wasn’t sleeping or eating well. Since then I’ve learned how my body reacts under too much stress and when I need to better balance my work and life. I realized what brought me peace and allowed me to re-centre myself, and that occurred because I started to understand who I was as a person. Now I know that I’m balancing my work and life well when on my days off I’m not worrying about what I have to do during the week.
If I have to work on weekends (for conferences, research and the like), then I take an equivalent amount of time off during the week. This is a valuable bit of advice I learned from one of my mentors. Although this is easier to do once you’ve finished classes and have a little bit more flexibility with your schedule, it’s always an important strategy for preventing burnout. It also makes me more productive, not less. When I start to burn out, sometimes it feels like I am giving 100%, but it’s only about 50% of what I can do when I’m not burned out.
When to take a break
Today my schedule is built around what works for me. I treat graduate school more like a 9-to-5 job, where I work only during specific hours. I make time to work out every day, because it allows me to focus on myself. My family is extremely important to me, and we are very close, so I try to talk with them almost every day, and once a week we play Dungeons and Dragons together remotely. We grew up playing that together in person, so it’s great to continue the tradition. After working, I try to spend part of my time every night reading, and I’ve recently found a lot of joy in cooking. Pursuing the things that bring you joy outside of work will help you maintain your mental health.
Sometimes, though, even with a good work–life balance, you may find that you’re struggling to stay motivated. At that point, it might be a good idea to take a break and step back from research, classes, and work things, kind of like a holiday. You can discuss this with your adviser and find out how it will affect your progress in your programme. This happened to me about a year ago. I went through something traumatic, and at the time I thought I was handling it fine. But after conversations with my mentors, I realized I needed to take a total break. Afterward it was like a huge weight was lifted off my shoulders, and I felt at peace and motivated to start up research again. The trauma that I went through didn’t just disappear; it was something I dealt with even after my break, and it was the reason I ended up transferring from West Virginia to Syracuse University. I struggled a lot with making the decision to transfer, but I realized it was ultimately the best decision for me. Sometimes things just don’t work out in one area, and that’s okay.
Recognizing when I needed to take a break came hand in hand with evaluating my mental health. There are certain signs for me – getting nauseous while eating or not being able to determine what my emotions are – that mean I am in dire need of a break. If I can recognize the signs before I get to the point where I need a long break of a month or more, I can combat them by taking off just a few days to a week. Taking a break might make you feel like you’re going to fall behind and not be able to catch up, but I promise that won’t happen. You’ll feel revitalized and be more motivated to keep going.


physicsworld--2020-10-27--Deep learning transforms standard CT scans towards spectral images - Physics World

Computed tomography ( CT ) is a popular medical imaging tool , visualizing and quantifying internal structures for screening , diagnosis , therapy planning and treatment monitoring .
Conventional clinical CT scans generate a spectrally integrated attenuation image that shows tissue morphology , but does not directly provide any information regarding tissue composition .
Dual-energy CT ( DECT ) systems , which acquire two spectrally distinct datasets , can reconstruct virtual monoenergetic ( VM ) and material-specific images that provide information about tissue composition .
Compared with conventional CT , however , DECT is more expensive and complex , and @ @ @ @ @ @ @ For patients without access to DECT scans , a way to approximate the information provided by DECT using a single-spectrum CT scan could improve clinical diagnoses .
With this aim , Wenxiang Cong and a team led by Ge Wang at Rensselaer Polytechnic Institute demonstrated a deep-learning approach that can produce VM images from single-spectrum CT scans .
“ With traditional CT , you take a greyscale image , but with dual-energy CT you take an image with two colours , ” explains Wang .
“ With deep learning , we try to @ @ @ @ @ @ @ the job of dual-energy CT imaging .
We hope that this technique will help extract more information from a regular single-spectrum X-ray CT scan , make it more quantitative and improve diagnosis.
” Wang and his team – in collaboration with Shanghai First-Imaging Tech and GE Research – modified a residual neural network ( ResNet ) to transform clinical single-spectrum CT images to VM counterparts .
After training the network on clinical DECT images , they used it to produce VM images at two energy levels ( 80 and 110 keV ) from @ @ @ @ @ @ @ excellent agreement with those produced by DECT reconstruction using two different spectra .
The model was able to produce high-quality approximations to linear attenuation coefficients with a relative error of less than 2 % .
The structural similarity between the two types of VM images was up to 0.99 , showing that structural information , especially texture features , was well preserved by the machine learning method .
Next , the team used the deep-learning-based VM images to generate material-specific images of three tissue types : adipose , muscle and bone .
The @ @ @ @ @ @ @ closely approximated those produced by DECT using projection datasets from two X-ray spectra .
The researchers note that the bone image could be clearly separated from the VM images .
Notably , a calcification in the abdominal aorta that was inconspicuous in the original polychromatic image was visible in the synthesized VM image and in the bone image .
This reveals one of the potential clinical utilities of the DL method .
Having demonstrated that a conventional CT dataset coupled with deep learning can deliver a close approximation of DECT images , the @ @ @ @ @ @ @ to use conventional CT to perform some important tasks currently achieved using DECT – thereby eliminating the hardware cost associated with a DECT scanner .
One example application is the determination of proton stopping power for use in proton therapy planning , where it is important to accurately represent material concentrations of common tissues along the therapeutic beam .
The team also highlight deep-learning-based VM imaging as an alternative to photon-counting micro-CT for in vivo preclinical applications .
The full details of the research are published in Patterns .

Top row: benchmark virtual monoenergetic (VM) images from dual-energy CT projection data reconstructed at 80 and 110 keV, respectively. Bottom row: corresponding VM images produced at the same energies from only 140-kVp images, using a deep learning approach. (Courtesy: Wenxiang Cong, Yan Xi, Paul Fitzgerald, Bruno De Man and Ge Wang)
Computed tomography (CT) is a popular medical imaging tool, visualizing and quantifying internal structures for screening, diagnosis, therapy planning and treatment monitoring. Conventional clinical CT scans generate a spectrally integrated attenuation image that shows tissue morphology, but does not directly provide any information regarding tissue composition.
Dual-energy CT (DECT) systems, which acquire two spectrally distinct datasets, can reconstruct virtual monoenergetic (VM) and material-specific images that provide information about tissue composition. Compared with conventional CT, however, DECT is more expensive and complex, and often requires an increased radiation dose.
For patients without access to DECT scans, a way to approximate the information provided by DECT using a single-spectrum CT scan could improve clinical diagnoses. With this aim, Wenxiang Cong and a team led by Ge Wang at Rensselaer Polytechnic Institute demonstrated a deep-learning approach that can produce VM images from single-spectrum CT scans.
“With traditional CT, you take a greyscale image, but with dual-energy CT you take an image with two colours,” explains Wang. “With deep learning, we try to use the standard CT machine to do the job of dual-energy CT imaging. We hope that this technique will help extract more information from a regular single-spectrum X-ray CT scan, make it more quantitative and improve diagnosis.”
Wang and his team – in collaboration with Shanghai First-Imaging Tech and GE Research – modified a residual neural network (ResNet) to transform clinical single-spectrum CT images to VM counterparts. After training the network on clinical DECT images, they used it to produce VM images at two energy levels (80 and 110 keV) from single-spectrum images. These VM images showed excellent agreement with those produced by DECT reconstruction using two different spectra.
The model was able to produce high-quality approximations to linear attenuation coefficients with a relative error of less than 2%. The structural similarity between the two types of VM images was up to 0.99, showing that structural information, especially texture features, was well preserved by the machine learning method.
Next, the team used the deep-learning-based VM images to generate material-specific images of three tissue types: adipose, muscle and bone. The resulting images were of high quality and closely approximated those produced by DECT using projection datasets from two X-ray spectra.
The researchers note that the bone image could be clearly separated from the VM images. Notably, a calcification in the abdominal aorta that was inconspicuous in the original polychromatic image was visible in the synthesized VM image and in the bone image. This reveals one of the potential clinical utilities of the DL method.
Having demonstrated that a conventional CT dataset coupled with deep learning can deliver a close approximation of DECT images, the researchers suggest that it is potentially feasible to use conventional CT to perform some important tasks currently achieved using DECT – thereby eliminating the hardware cost associated with a DECT scanner.
One example application is the determination of proton stopping power for use in proton therapy planning, where it is important to accurately represent material concentrations of common tissues along the therapeutic beam. The team also highlight deep-learning-based VM imaging as an alternative to photon-counting micro-CT for in vivo preclinical applications.
The full details of the research are published in Patterns.


physicsworld--2020-10-27--Hypofractionation: pushing the boundaries of MLC performance - Physics World

The clinical upside of hypofractionated radiation therapy has been evident for some time , with cancer patients benefiting from increased dose per fraction such that they can complete their course of radiotherapy much faster than is possible with conventional treatment schedules – and just as safely and effectively .
Think fewer hospital visits , a speedier return to family and , for some indications , enhanced treatability and outcomes .
Equally compelling is the long-term opportunity for healthcare providers , with higher dose per fraction ( and fewer fractions ) translating into significant workflow efficiencies , lower cost of care @ @ @ @ @ @ @ – all of which looks even more compelling against a backdrop of growing cancer incidence worldwide and the perfect storm of the coronavirus pandemic .
Right now , though , the challenge for radiotherapy OEMs and the wider supply chain is to come up with the enabling technologies and treatment protocols to realize these clinical and economic outcomes at scale .
For starters , the radiation oncology team needs the ability to maintain submillimetre accuracy and precision throughout treatment delivery – identifying the target location in the body ; automatically detecting , tracking @ @ @ @ @ @ @ to breathing and peristalsis , for example ) ; and accurately repointing the beam in real-time to support the clinical use of smaller margins to reduce the side-effects of treatment .
With this in mind , a German R & D initiative is aiming to realize a “ new gold standard ” in the performance of the so-called multileaf collimator ( MLC ) , a core building block of the radiotherapy linacs used for cutting-edge cancer treatments like hypofractionation and ultrahypofractionation .
The industry–academia joint venture , which earlier this year received backing @ @ @ @ @ @ @ together laser and radiotherapy QA specialist LAP with the Institute for Medical Engineering of the Ostbayerische Technische Hochschule ( OTH ) Amberg-Weiden .
Their goal : a next-generation drive and control unit that promises an order-of-magnitude improvement in the speed and precision of the MLC subsystem – and specifically the array of independently controlled tungsten “ leaves ” ( typically between 120 and 160 ) used to shape and vary the intensity of the treatment beam as it addresses the tumour volume .
The commercial imperative for MLC development is a mix of @ @ @ @ @ @ @ Stefan Ueltzhöffer , who heads up LAP ’ s MLC and radiotherapy QA business .
“ We follow the market closely , ” he explains , “ and maintain an ongoing dialogue with the radiotherapy equipment supply chain , the clinical user base and our academic partners .
It ’ s clear from those conversations that emerging treatment modalities like hypofractionation and MR-guided radiotherapy ( MR/RT ) will benefit from MLC innovation , creating opportunities for subsystem suppliers like us to set new standard in terms of MLC performance.
” From that starting @ @ @ @ @ @ @ inform the development roadmap for LAP ’ s MLC product line .
First , how does LAP address the evolving needs of its customers ( the radiotherapy OEMs ) and customers ’ customer ( the radiation oncology clinics ) ?
Second , what does differentiation of that MLC offering look like to enable LAP to gain market-share versus its competition ?
The answer , it seems , is a next-generation MLC that will consolidate the outcomes of various in-house development projects with the efforts of this latest collaboration with OTH .
“ Ultimately @ @ @ @ @ @ @ believe we will be talking about multiples of improvement in terms of MLC speed and precision , after pretty much only incremental changes in the technology over the past 20 years.
” Yet while LAP is clearly pushing for a step-function breakthrough in MLC performance , it ’ s also a given that any advanced capabilities must deliver against strict cost/performance criteria .
“ Pragmatism is key – the MLC is no longer a toy only for physicists , ” notes Ueltzhöffer .
“ From a commercial and clinical perspective , we want @ @ @ @ @ @ @ serviceable and easier to manufacture .
As such , the innovations we are evaluating will enhance performance without sacrificing the considerable progress made on cost and machinability over the past decade.
” If that ’ s the commercial context , what of the technical progress to date ?
According to Ueltzhöffer , several advanced MLC technologies are already in the works and shaping up well in proof-of-concept demonstrators at LAP .
One particular area of focus right now is the MLC drive , with a simplified set-up expected to yield significant outcomes in @ @ @ @ @ @ @ designed-in MR compatibility ( to minimize the need for shielding in MR/RT treatment systems ) .
“ The MLC drive has always been quite cumbersome in terms of the size of the motors and associated sensors , ” says Ueltzhöffer .
“ As such , we are looking at easier-to-integrate modules that could lead to a lot more degrees of freedom in designing the MLC subsystem – and maybe even make it possible to get rid of some of the transmission mechanisms.
” Another development track is evaluating the use of laser-based sensors @ @ @ @ @ @ @ the MLC leaves – a traditional pain-point for today ’ s MLC designs which rely on cameras , other optical sensors or potentiometers to do that job .
“ It ’ s a no-brainer , ” says Ueltzhöffer .
“ We ’ re applying diverse laser technologies and specialist domain knowledge from the wider LAP group to support our MLC innovation programme.
” If the technology end-point is clear – a new generation of MLCs and a “ big leap forward ” in capability – the commercial outcome appears more fluid and nuanced @ @ @ @ @ @ @ intends to grow its market-share by supplying turnkey MLC units for OEM equipment vendors to integrate directly into their radiotherapy machines .
Equally , Ueltzhöffer also plans to license key MLC technologies – for example , drives , sensors and controllers – to those OEM equipment vendors who prefer to build their own MLC subsystems .
“ More broadly , ” concludes Ueltzhöffer , “ LAP remains focused on delivering the enabling technologies for next-generation radiotherapy – in particular , emerging modalities like hypofractionation and MR/RT – through ongoing innovation across its MLC @ @ @ @ @ @ @ ” See also the LAP webinars Maximizing QA accuracy and efficiency with RadCalc in a challenging environment and Commissioning and QA workflows of MR-linac with the Thales 3D MR scanner .

A German R&D collaboration is pursuing an ambitious development roadmap to realize a next-generation multileaf collimator
The shape of things to come: LAP and OTH Amberg-Weiden are developing a next-generation drive and control unit that promises an order-of-magnitude improvement in the speed and precision of the MLC subsystem. (Courtesy: LAP)
The clinical upside of hypofractionated radiation therapy has been evident for some time, with cancer patients benefiting from increased dose per fraction such that they can complete their course of radiotherapy much faster than is possible with conventional treatment schedules – and just as safely and effectively. Think fewer hospital visits, a speedier return to family and, for some indications, enhanced treatability and outcomes. Equally compelling is the long-term opportunity for healthcare providers, with higher dose per fraction (and fewer fractions) translating into significant workflow efficiencies, lower cost of care and, ultimately, increased patient throughput – all of which looks even more compelling against a backdrop of growing cancer incidence worldwide and the perfect storm of the coronavirus pandemic.
Right now, though, the challenge for radiotherapy OEMs and the wider supply chain is to come up with the enabling technologies and treatment protocols to realize these clinical and economic outcomes at scale. For starters, the radiation oncology team needs the ability to maintain submillimetre accuracy and precision throughout treatment delivery – identifying the target location in the body; automatically detecting, tracking and correcting for target motion (due to breathing and peristalsis, for example); and accurately repointing the beam in real-time to support the clinical use of smaller margins to reduce the side-effects of treatment.
With this in mind, a German R&D initiative is aiming to realize a “new gold standard” in the performance of the so-called multileaf collimator (MLC), a core building block of the radiotherapy linacs used for cutting-edge cancer treatments like hypofractionation and ultrahypofractionation. The industry–academia joint venture, which earlier this year received backing from the Bavarian regional government, brings together laser and radiotherapy QA specialist LAP with the Institute for Medical Engineering of the Ostbayerische Technische Hochschule (OTH) Amberg-Weiden. Their goal: a next-generation drive and control unit that promises an order-of-magnitude improvement in the speed and precision of the MLC subsystem – and specifically the array of independently controlled tungsten “leaves” (typically between 120 and 160) used to shape and vary the intensity of the treatment beam as it addresses the tumour volume.
Innovation meets pragmatism
The commercial imperative for MLC development is a mix of technology push and market pull, claims Stefan Ueltzhöffer, who heads up LAP’s MLC and radiotherapy QA business. “We follow the market closely,” he explains, “and maintain an ongoing dialogue with the radiotherapy equipment supply chain, the clinical user base and our academic partners. It’s clear from those conversations that emerging treatment modalities like hypofractionation and MR-guided radiotherapy (MR/RT) will benefit from MLC innovation, creating opportunities for subsystem suppliers like us to set new standard in terms of MLC performance.”
Stefan Ueltzhöffer: “From a commercial and clinical perspective, we want MLCs that are more stable, more serviceable and easier to manufacture.” (Courtesy: LAP)
From that starting point, argues Ueltzhöffer, two questions inform the development roadmap for LAP’s MLC product line. First, how does LAP address the evolving needs of its customers (the radiotherapy OEMs) and customers’ customer (the radiation oncology clinics)? Second, what does differentiation of that MLC offering look like to enable LAP to gain market-share versus its competition? The answer, it seems, is a next-generation MLC that will consolidate the outcomes of various in-house development projects with the efforts of this latest collaboration with OTH. “Ultimately,” adds Ueltzhöffer, “I believe we will be talking about multiples of improvement in terms of MLC speed and precision, after pretty much only incremental changes in the technology over the past 20 years.”
Yet while LAP is clearly pushing for a step-function breakthrough in MLC performance, it’s also a given that any advanced capabilities must deliver against strict cost/performance criteria. “Pragmatism is key – the MLC is no longer a toy only for physicists,” notes Ueltzhöffer. “From a commercial and clinical perspective, we want MLCs that are more stable, more serviceable and easier to manufacture. As such, the innovations we are evaluating will enhance performance without sacrificing the considerable progress made on cost and machinability over the past decade.”
Play to your strengths
If that’s the commercial context, what of the technical progress to date? According to Ueltzhöffer, several advanced MLC technologies are already in the works and shaping up well in proof-of-concept demonstrators at LAP. One particular area of focus right now is the MLC drive, with a simplified set-up expected to yield significant outcomes in terms of reduced footprint, weight and designed-in MR compatibility (to minimize the need for shielding in MR/RT treatment systems).
“The MLC drive has always been quite cumbersome in terms of the size of the motors and associated sensors,” says Ueltzhöffer. “As such, we are looking at easier-to-integrate modules that could lead to a lot more degrees of freedom in designing the MLC subsystem – and maybe even make it possible to get rid of some of the transmission mechanisms.”
Another development track is evaluating the use of laser-based sensors to provide optical encoding and tracking of the MLC leaves – a traditional pain-point for today’s MLC designs which rely on cameras, other optical sensors or potentiometers to do that job. “It’s a no-brainer,” says Ueltzhöffer. “We’re applying diverse laser technologies and specialist domain knowledge from the wider LAP group to support our MLC innovation programme.”
If the technology end-point is clear – a new generation of MLCs and a “big leap forward” in capability – the commercial outcome appears more fluid and nuanced. On the one hand, LAP intends to grow its market-share by supplying turnkey MLC units for OEM equipment vendors to integrate directly into their radiotherapy machines. Equally, Ueltzhöffer also plans to license key MLC technologies – for example, drives, sensors and controllers – to those OEM equipment vendors who prefer to build their own MLC subsystems.
“More broadly,” concludes Ueltzhöffer, “LAP remains focused on delivering the enabling technologies for next-generation radiotherapy – in particular, emerging modalities like hypofractionation and MR/RT – through ongoing innovation across its MLC, QA and laser positioning product lines.”
Further reading
See also the LAP webinars Maximizing QA accuracy and efficiency with RadCalc in a challenging environment and Commissioning and QA workflows of MR-linac with the Thales 3D MR scanner.


physicsworld--2020-10-27--‘Mutual detectability’ will improve the search for extraterrestrial civilizations - Physics World

The search for extraterrestrial intelligence ( SETI ) is slowly evolving from a fringe endeavor to a more mainstream one thanks to improvements in the capability of astronomical surveys , detector sensitivity , and greater philanthropic financial support .
Still , because of the vastness of the universe and the scarcity of resources , scientists must develop strategies around where , when , and how to discover alien civilizations .
Much of SETI involves trying to receive signals broadcast by other civilizations .
However , it could be that every civilization in the universe has decided that transmitting messages for @ @ @ @ @ @ @ dangerous , but that listening for messages sent by others is a safe and worthwhile pursuit .
This “ SETI Paradox ” would leave all SETI efforts doomed to failure because for any civilization ’ s SETI efforts to succeed , some other civilization must engage in messaging extraterrestrial intelligence ( METI ) .
One important question is how two civilizations should coordinate their efforts to discover each other , given that they are not certain about each other ’ s existence .
Another is which civilization should send a message , and @ @ @ @ @ @ @ preprint , astronomer Eamonn Kerins of the UK ’ s University of Manchester has developed a game-theory framework that determines not only how and where civilizations should target their efforts , but also which of two such civilizations has the onus to send a message , and which should be listening for that message .
As Jason Wright , professor of astronomy and astrophysics at Penn State , summarizes , “ Kerins ’ idea is that the symmetry that keeps us all from transmitting can be broken by recognizing that some species have @ @ @ @ @ @ @ , and that the ‘ onus to transmit ’ should lie with them ” .
He adds , “ It ’ s a neat approach and suggests that there are systems towards which we have the onus to transmit and should be contacting , while other [ planets ] are better targets for listening .
If other species are following the same logic , then this should make SETI programs more efficient and likely to succeed.
” Kerins considers the scenario in which both civilizations can gather data that suggests the existence of @ @ @ @ @ @ @ should gather similar data because only when the data are comparable would the civilizations possess “ mutual ” information – which is key to Kerins ’ framework .
Because the civilizations may vastly differ in their technological capabilities , it is important that they both consider the simplest possible evidence of the other ’ s existence .
Kerins proposes that civilizations should use “ common denominator information ” ( CDI ) to find potential SETI/METI targets .
CDI is evidence that both parties can recognize , and that is independent of either party @ @ @ @ @ @ @ .
Kerins offers the example of the amount of starlight blocked by a planet as it transits across its host star – which is called the transit ’ s signal strength .
This quantity is simple enough that any civilization engaged in SETI/METI efforts should be capable of measuring it , and it is also independent of how the measurement is made .
In this sense , a transit ’ s signal strength is “ intrinsic ” and therefore can be compared by two civilizations who are looking for one another .
Crucially @ @ @ @ @ @ @ determine not only their own signal strength as the other party would measure it , but also the signal strength of the other planet .
Then , each party would know what the other knows , and therefore both parties know who has the superior evidence about the other ’ s potential existence .
Kerins argues that whichever party has superior information has the greater incentive to send a message to the other – the onus to transmit – while the party with inferior information should listen for a signal .
On where @ @ @ @ @ @ @ , Kerins points to planets in the “ Earth ’ s transit zone ” ( ETZ ) , a slice of space in which an observer can watch Earth transit the Sun .
“ From the basic idea of transits , and with technology comparable to ours , [ extraterrestrial civilizations in the ETZ ] can work out that we are a potentially habitable planet , ” says Kerins .
“ The transit method is among the first methods that any civilization capable of finding other planets would establish .
Therefore , if @ @ @ @ @ @ @ by using the transit method , we ’ ll hopefully embrace most of them , because they ’ ll also have knowledge of the transit method .
The situation in which we ’ re looking at a region of the sky where we can see them in transit and they can see us in transit maximizes our chances of success.
” The preprint has been accepted for publication in The Astronomical Journal .

Big sky: where and when should we send signals to potential extraterrestrial civilizations? (Courtesy: John Masterson/CSIRO/CC BY 3.0)
The search for extraterrestrial intelligence (SETI) is slowly evolving from a fringe endeavor to a more mainstream one thanks to improvements in the capability of astronomical surveys, detector sensitivity, and greater philanthropic financial support. Still, because of the vastness of the universe and the scarcity of resources, scientists must develop strategies around where, when, and how to discover alien civilizations.
Much of SETI involves trying to receive signals broadcast by other civilizations. However, it could be that every civilization in the universe has decided that transmitting messages for other civilizations to receive is unwise or dangerous, but that listening for messages sent by others is a safe and worthwhile pursuit.
This “SETI Paradox” would leave all SETI efforts doomed to failure because for any civilization’s SETI efforts to succeed, some other civilization must engage in messaging extraterrestrial intelligence (METI). One important question is how two civilizations should coordinate their efforts to discover each other, given that they are not certain about each other’s existence. Another is which civilization should send a message, and which should listen.
Onus to transmit
In a recent preprint, astronomer Eamonn Kerins of the UK’s University of Manchester has developed a game-theory framework that determines not only how and where civilizations should target their efforts, but also which of two such civilizations has the onus to send a message, and which should be listening for that message.
As Jason Wright, professor of astronomy and astrophysics at Penn State, summarizes, “Kerins’ idea is that the symmetry that keeps us all from transmitting can be broken by recognizing that some species have access to more information about other planets, and that the ‘onus to transmit’ should lie with them”. He adds, “It’s a neat approach and suggests that there are systems towards which we have the onus to transmit and should be contacting, while other [planets] are better targets for listening. If other species are following the same logic, then this should make SETI programs more efficient and likely to succeed.”
Kerins considers the scenario in which both civilizations can gather data that suggests the existence of the other. Ideally, each civilization should gather similar data because only when the data are comparable would the civilizations possess “mutual” information – which is key to Kerins’ framework. Because the civilizations may vastly differ in their technological capabilities, it is important that they both consider the simplest possible evidence of the other’s existence.
“Common denominator information”
Kerins proposes that civilizations should use “common denominator information” (CDI) to find potential SETI/METI targets. CDI is evidence that both parties can recognize, and that is independent of either party’s particular method of acquiring information. Kerins offers the example of the amount of starlight blocked by a planet as it transits across its host star – which is called the transit’s signal strength.
This quantity is simple enough that any civilization engaged in SETI/METI efforts should be capable of measuring it, and it is also independent of how the measurement is made. In this sense, a transit’s signal strength is “intrinsic” and therefore can be compared by two civilizations who are looking for one another. Crucially, each party should be able to determine not only their own signal strength as the other party would measure it, but also the signal strength of the other planet. Then, each party would know what the other knows, and therefore both parties know who has the superior evidence about the other’s potential existence.
Kerins argues that whichever party has superior information has the greater incentive to send a message to the other – the onus to transmit – while the party with inferior information should listen for a signal.
On where and how to implement his game-theory framework, Kerins points to planets in the “Earth’s transit zone” (ETZ), a slice of space in which an observer can watch Earth transit the Sun. “From the basic idea of transits, and with technology comparable to ours, [extraterrestrial civilizations in the ETZ] can work out that we are a potentially habitable planet,” says Kerins. “The transit method is among the first methods that any civilization capable of finding other planets would establish. Therefore, if there are SETI-capable civilizations out there, by using the transit method, we’ll hopefully embrace most of them, because they’ll also have knowledge of the transit method. The situation in which we’re looking at a region of the sky where we can see them in transit and they can see us in transit maximizes our chances of success.”
The preprint has been accepted for publication in The Astronomical Journal.


physicsworld--2020-10-28--The disability is there, but I belong - Physics World

When I walk into a room , most people see me as confident and ready to take on the world .
As an engineer in the aerospace industry , that ’ s the persona I would like them to see .
But in reality , I ’ m most likely experiencing a serious level of anxiety stimulated by my invisible disability .
The Invisible Disabilities Association defines an invisible disability as a physical , mental or neurological condition that can ’ t be seen from the outside yet can limit or challenge a person ’ s movements , senses or @ @ @ @ @ @ @ Most people I know forget that I deal with this disability daily .
My speech is not altered , and my hearing aids are small enough for most people to miss them .
But within academia , once I disclose my disability , there is an almost immediate assumption that I have some type of intellectual deficiency .
Hearing is the ability to perceive sound by detecting vibrations through your ears .
Sound waves enter the outer ear and travel to your eardrum , which through some detailed process creates an electrical signal @ @ @ @ @ @ @ brain .
There the signal becomes something that we recognize and understand .
A hearing impairment or hearing loss is a full or partial decrease in the ability to detect or understand sounds .
My hearing loss is in the range of frequencies used for speech .
I have extreme difficulty with heavily accented speakers from other parts of the US or different countries , as well as in excessively noisy environments , like conferences .
I ’ m always on high alert when moving in these environments , making sure my brain @ @ @ @ @ @ @ to hold up my end of an intellectual conversation .
Hearing is exhausting when you suffer from a hearing loss .
I ’ m constantly focused on making sure that my frustration doesn ’ t show when I don ’ t hear clearly or am missing gaps of conversation because my brain hasn ’ t processed what was said .
I dread having to ask colleagues to repeat themselves because they always rephrase their statement as if I didn ’ t understand its meaning , versus just not hearing the words .
Even @ @ @ @ @ @ @ disability , many of you can identify with me in different ways .
When I walk into a room , I ’ m Black .
When I walk into a room , I ’ m a woman .
When I walk into a room , I ’ m a Black woman .
Different people process these things differently .
Historically , Black people have been perceived as less intelligent , and even though physics is considered an elite intellectual pursuit , there are some who believe that Black physicists are in the field @ @ @ @ @ @ @ affirmative action or because of luck .
The current political environment has allowed racism to rear its ugly head , amplifying the negative experiences for African Americans , even in our field .
Add to that my disability , and some have questioned whether I have the intellectual capacity to be in physics .
In graduate school I had a professor whom I had a lot of trouble understanding .
I was unable to process any of what he was saying , even with all my accommodations in place .
I earned a @ @ @ @ @ @ @ to my being placed on academic probation .
I had to retake the class with the same professor .
Knowing I needed a new approach , I went to the professor to try and work something out .
His response was “ You are the dumbest student I ’ ve ever taught.
” I ’ ve never forgotten these words .
They are what pushed me to work my butt off from that day forward .
In this situation , my race and gender didn ’ t matter – my disability was the @ @ @ @ @ @ @ my professor was a pivotal moment in my academic career because it forced me to take ownership of my disability and not let it lead me .
Several years ago I attended an International Union of Pure and Applied Physics conference as a member of the organizing committee for the Women in Physics Working Group .
I applied for a grant to accommodate my disability at the conference .
However , one of my colleagues – a grant administrator and a white American woman – decided she knew what was best and overrode @ @ @ @ @ @ @ .
Her decision caused several days of frustration , several tears and several days of not being able to fully participate in the conference .
Eventually the conference made the accommodations I needed , and I was able to fully participate and fulfil my functional responsibilities .
It cost the conference organizers twice as much as the amount in my grant request .
I processed this experience as a microaggression , which the Oxford English Dictionary defines as “ an instance of indirect , subtle , or unintentional discrimination against members of a @ @ @ @ @ @ @ ethnic minority ” .
My colleague needed to be in control of the entire situation , and she decided I either didn ’ t know what was best for me or wasn ’ t worth the cost of the accommodation I needed .
She perceived me as aggressive and angry because I wanted the accommodation corrected , as is my civil right under the Americans with Disabilities Act of 1990 .
I ’ ve pointed out my hidden disability .
Know that there are so many more people who similarly suffer from other @ @ @ @ @ @ @ hardest thing to navigate is knowing if people have issues with me because I ’ m Black , because I ’ m a woman , because I ’ m a Black woman , because I ’ m a person with a disability , because they perceive that I have an edge due to my accommodations , or because of a combination of all my intersecting identities – none of which I could change even if I wanted to .
Just a small reminder to anyone who doubts me : I belong here .
@ @ @ @ @ @ @ space at the anxiety associated with my disability , but I won ’ t be going away .

This article is the fourth in a series of essays written by Black physicists and co-published with Physics Today as part of #BlackInPhysics Week, an event dedicated to celebrating Black physicists and their contributions to the scientific community, and to revealing a more complete picture of what a physicist looks like.
Assume nothing K Renee Horton’s invisible disability of hearing loss and her visible identity as a Black woman in science interact in complex ways. (Courtesy: Steven Seipel)
When I walk into a room, most people see me as confident and ready to take on the world. As an engineer in the aerospace industry, that’s the persona I would like them to see. But in reality, I’m most likely experiencing a serious level of anxiety stimulated by my invisible disability.
The Invisible Disabilities Association defines an invisible disability as a physical, mental or neurological condition that can’t be seen from the outside yet can limit or challenge a person’s movements, senses or activities. Mine is hearing loss. Most people I know forget that I deal with this disability daily. My speech is not altered, and my hearing aids are small enough for most people to miss them. But within academia, once I disclose my disability, there is an almost immediate assumption that I have some type of intellectual deficiency.
Hearing is the ability to perceive sound by detecting vibrations through your ears. Sound waves enter the outer ear and travel to your eardrum, which through some detailed process creates an electrical signal that the auditory nerve carries to the brain. There the signal becomes something that we recognize and understand. A hearing impairment or hearing loss is a full or partial decrease in the ability to detect or understand sounds. My hearing loss is in the range of frequencies used for speech. I have extreme difficulty with heavily accented speakers from other parts of the US or different countries, as well as in excessively noisy environments, like conferences. I’m always on high alert when moving in these environments, making sure my brain has processed what I heard and trying to hold up my end of an intellectual conversation.
Hearing is exhausting when you suffer from a hearing loss. I’m constantly focused on making sure that my frustration doesn’t show when I don’t hear clearly or am missing gaps of conversation because my brain hasn’t processed what was said. I dread having to ask colleagues to repeat themselves because they always rephrase their statement as if I didn’t understand its meaning, versus just not hearing the words.
Even if you don’t have a disability, many of you can identify with me in different ways. When I walk into a room, I’m Black. When I walk into a room, I’m a woman. When I walk into a room, I’m a Black woman. Different people process these things differently. Historically, Black people have been perceived as less intelligent, and even though physics is considered an elite intellectual pursuit, there are some who believe that Black physicists are in the field or in their jobs only because of affirmative action or because of luck. The current political environment has allowed racism to rear its ugly head, amplifying the negative experiences for African Americans, even in our field. Add to that my disability, and some have questioned whether I have the intellectual capacity to be in physics.
Barriers to full participation
In graduate school I had a professor whom I had a lot of trouble understanding. I was unable to process any of what he was saying, even with all my accommodations in place. I earned a C in this class, which led to my being placed on academic probation. I had to retake the class with the same professor. Knowing I needed a new approach, I went to the professor to try and work something out. His response was “You are the dumbest student I’ve ever taught.” I’ve never forgotten these words. They are what pushed me to work my butt off from that day forward. In this situation, my race and gender didn’t matter – my disability was the only hindering factor. The meeting with my professor was a pivotal moment in my academic career because it forced me to take ownership of my disability and not let it lead me.
Several years ago I attended an International Union of Pure and Applied Physics conference as a member of the organizing committee for the Women in Physics Working Group. I applied for a grant to accommodate my disability at the conference. However, one of my colleagues – a grant administrator and a white American woman – decided she knew what was best and overrode my accommodation requests with her own choices. Her decision caused several days of frustration, several tears and several days of not being able to fully participate in the conference.
Eventually the conference made the accommodations I needed, and I was able to fully participate and fulfil my functional responsibilities. It cost the conference organizers twice as much as the amount in my grant request. I processed this experience as a microaggression, which the Oxford English Dictionary defines as “an instance of indirect, subtle, or unintentional discrimination against members of a marginalized group such as a racial or ethnic minority”. My colleague needed to be in control of the entire situation, and she decided I either didn’t know what was best for me or wasn’t worth the cost of the accommodation I needed. She perceived me as aggressive and angry because I wanted the accommodation corrected, as is my civil right under the Americans with Disabilities Act of 1990.
Intersecting identities
I’ve pointed out my hidden disability. Know that there are so many more people who similarly suffer from other types of invisible disabilities. Sometimes the hardest thing to navigate is knowing if people have issues with me because I’m Black, because I’m a woman, because I’m a Black woman, because I’m a person with a disability, because they perceive that I have an edge due to my accommodations, or because of a combination of all my intersecting identities – none of which I could change even if I wanted to.
Just a small reminder to anyone who doubts me: I belong here. I may keep crying in my personal space at the anxiety associated with my disability, but I won’t be going away.


physicsworld--2020-10-28--Graphene oxide microbubbles are near-perfect microlenses - Physics World

A new and robust technique for generating microbubbles in films of graphene oxide has been developed by researchers in Australia , Singapore and the US .
Using ultrashort laser pulses , a team led by Han Lin at Swinburne University of Technology created stable bubbles with highly controllable volumes , curvatures , and positions .
They then used the structures to make a near-perfect microlenses for producing photonic jets from white light .
With further research , their technique could see a broad range of uses in other areas .
From inkjet printing to DNA manipulation , microbubbles have found @ @ @ @ @ @ @ applications .
Currently , they are generated by firing ultrasound waves or laser pulses onto solid substrates like silicon chips .
For the process to work , however , these substrates must be immersed in liquids – resulting in unstable bubbles that form in random places .
This makes them unsuitable for integration with many biological and photonics applications – which require highly stable bubbles with controllable volumes and curvatures .
Lin ’ s team gained better control over the process by placing a film of graphene oxide onto a substrate , which @ @ @ @ @ @ @ pulses .
This triggers a chemical reaction that releases gases , which become trapped by the impermeable film .
Through careful control of the laser power and its exposure area , the researchers could finely tune the amount of gas released .
This gives them precise control over the volumes and curvatures of the resulting microbubbles as well as the locations of the bubbles .
Furthermore , the microbubbles can easily be eliminated by increasing the laser power and destroying the film .
To showcase the applicability of their graphene oxide microbubbles , @ @ @ @ @ @ @ surfaces and almost perfectly spherical curvatures to create microlenses .
These can focus a range of optical wavelengths , without any unwanted dispersion .
They demonstrated this capability by using a microlens to focus white light with a broad range of wavelengths into an intense photonic jet , which they concentrated onto a single focal point with no chromatic aberration .
The team says that the technique offers clear advantages over photonic jet generation with glass microspheres .
Compared with this more traditional approach , the extremely high tuneability of the graphene oxide @ @ @ @ @ @ @ lengths and an insensitivity to material dispersion .
These attributes are highly desirable in applications including 3D biological imaging in miniaturized lab-on-a-chip devices .
Ultimately , the team ’ s discoveries open up promising new routes towards the application of microbubbles in a broad range of situations , including imaging , spectroscopy , and sensing .
The research is described in Advanced Photonics .

Bubble makers: Han Lin (left) and Baohua Jia at Swinburne’s Centre for Translational Atomaterials were involved in the microlens development. (Courtesy: Swinburne University of Technology)
A new and robust technique for generating microbubbles in films of graphene oxide has been developed by researchers in Australia, Singapore and the US. Using ultrashort laser pulses, researchers led by Han Lin at Swinburne University of Technology created stable bubbles with highly controllable volumes, curvatures, and positions. They then used the structures to make a near-perfect microlenses for producing photonic jets from white light. With further research, their technique could see a broad range of uses in other areas.
From inkjet printing to DNA manipulation, microbubbles have found uses in a diverse array of practical applications. Currently, they are generated by firing ultrasound waves or laser pulses onto solid substrates like silicon chips. For the process to work, however, these substrates must be immersed in liquids – resulting in unstable bubbles that form in random places. This makes them unsuitable for integration with many biological and photonics applications – which require highly stable bubbles with controllable volumes and curvatures.
Lin’s team gained better control over the process by placing a film of graphene oxide onto a substrate, which it irradiated with highly focused femtosecond laser pulses. This triggers a chemical reaction that releases gases, which become trapped by the impermeable film. Through careful control of the laser power and its exposure area, the researchers could finely tune the amount of gas released. This gives them precise control over the volumes and curvatures of the resulting microbubbles as well as the locations of the bubbles. Furthermore, the microbubbles can easily be eliminated by increasing the laser power and destroying the film.
Intense photonic jet
To showcase the applicability of their graphene oxide microbubbles, Lin and colleagues exploited their highly uniform surfaces and almost perfectly spherical curvatures to create microlenses. These can focus a range of optical wavelengths, without any unwanted dispersion. They demonstrated this capability by using a microlens to focus white light with a broad range of wavelengths into an intense photonic jet, which they concentrated onto a single focal point with no chromatic aberration.
The team says that the technique offers clear advantages over photonic jet generation with glass microspheres. Compared with this more traditional approach, the extremely high tunability of the graphene oxide microbubbles means that micolenses have arbitrary focal lengths and an insensitivity to material dispersion. These attributes are highly desirable in applications including 3D biological imaging in miniaturized lab-on-a-chip devices. Ultimately, the team’s discoveries open up promising new routes towards the application of microbubbles in a broad range of situations, including imaging, spectroscopy, and sensing.
The research is described in Advanced Photonics.


physicsworld--2020-10-28--Could hydrogen peroxide generation underlie mini- and micro-beam radiotherapy efficacy? - Physics Wo

Could hydrogen peroxide generation underlie mini- and micro-beam radiotherapy efficacy? - Physics World

Micro- and mini-beam radiation therapies ( MBRTs ) have been shown in animal experiments to effectively destroy tumours while minimizing damage to normal tissue nearby .
MBRT is delivered by irradiating a tumour with a series of high-dose beamlets of protons or photons alternated with low-dose valleys .
The reduced side-effects to organs-at-risk are thought to be due to the differential response of normal and tumour tissue to such spatially fractionated radiation .
The mechanisms underlying this differential response , however , are still unknown .
Aiming to fill this gap in knowledge , researchers in Germany have proposed and @ @ @ @ @ @ @ efficacy of mini-beams and micro-beams .
The team performed a simulation study to find a surrogate to the tumour control seen in MBRT .
Building on a proposed correlation between tissue damage and the level of reactive oxygen species ( ROS ) in tissue , they examined whether the distribution of a radiation-induced molecule or radical could provide such a surrogate .
“ From all published animal studies with micro- and mini-beams , it was clear that dose coverage of the tumour in the valley region was too low to allow any form @ @ @ @ @ @ @ delivered to the tumour was not a good surrogate for establishing the biological effect , ” explains senior author Joao Seco from DKFZ .
“ Several years ago , my group started working in radiochemistry , with the focus of evaluating which radical or molecule could be a good surrogate of biological effect.
” In a study described in Frontiers in Physics , Seco and colleagues investigated 12 potential generic radicals and molecules ( gRMs ) produced by a radiation beam .
As physical dose coverage is not achieved in MBRT , they @ @ @ @ @ @ @ by the distribution of such a gRM reaching a uniform coverage of the tumour target .
As such , they proposed that a candidate gRM must meet four conditions : it should be stable enough to diffuse during beam-on to cover the dose-valley regions ; it should reach a steady state in production versus removal , within a few microseconds ; it should be a product of water radiolysis ; and it should have oxidizing capacity to create cellular damage .
The researchers , also from Heidelberg University and GSI , used the @ @ @ @ @ @ @ production , removal and diffusion of the 12 gRMs .
The simulations revealed that the steady state was only reached by three of the gRMs , with only one of these – hydrogen peroxide ( H O ) – an oxidizing species .
Thus they restricted all further analysis to H O .
To assess the potential of H O as a candidate for the biological efficacy of MBRT , the researchers evaluated their simulations against previous animal experiments .
One limitation of TRAX-CHEM is that it only runs up to 10-6 s. @ @ @ @ @ @ @ suitable for experimental comparison ( up to 103 s ) , they modelled the time evolution of H O with a convolution model that uses a Gaussian Kernel ( calculated from TRAX-CHEM ) to convert delivered dose into H O spatial distribution at a specified time .
They calculated the H O spatial distribution for four proton mini-beam and photon micro-beam studies , using the published values of peak spacing , peak FWHM and peak-to-valley dose ratio ( PVDR ) .
Based on these parameters , they calculated the beam-on time at which @ @ @ @ @ @ @ tumour coverage .
Comparisons with the actual irradiation times revealed that the calculated minimum irradiation times were reached in three of the four experiments .
In these cases , the predicted H O distribution had a coverage of at least 95 % .
The team note that these three experiments were all associated with high probabilities of tumour ablation or growth delay .
In the experiment that did not reach the minimum beam-on time , the model predicted that H O did not uniformly cover the target .
In this experiment ( which @ @ @ @ @ @ @ two tumours were ablated in 32 irradiated rats .
In contrast , an experiment using the same synchrotron beams but with smaller spacing , in which H O diffused uniformly over the target , produced five tumour ablations out of 11 rats .
The researchers surmise therefore that homogeneous H O distribution is a highly relevant parameter for tumour ablation and should be further investigated .
The fact that this uniform coverage may be generated in the tumour but not in normal tissue , combined with the higher tolerance of normal cells to @ @ @ @ @ @ @ underlie the differential effect between tumour and normal tissue in MBRT .
Seco notes that the developed model can be used to assess whether MBRT will provide uniform H O coverage of the tumour volume .
There is still a need , however , to investigate the correlation between this coverage and treatment response .
The team is looking to discuss with other groups a possible animal study to understand how H O could be used to quantify treatment response .
“ In our study , we demonstrated that we should use H @ @ @ @ @ @ @ marker of biological effect for micro- and mini-beam radiotherapy , ” Seco concludes .

Joao Seco and colleagues are investigating how radiation mini- or micro-beams can destroy tumours while sparing nearby normal tissue. (Courtesy: Joao Seco)
Micro- and mini-beam radiation therapies (MBRTs) have been shown in animal experiments to effectively destroy tumours while minimizing damage to normal tissue nearby. MBRT is delivered by irradiating a tumour with a series of high-dose beamlets of protons or photons alternated with low-dose valleys. The reduced side-effects to organs-at-risk are thought to be due to the differential response of normal and tumour tissue to such spatially fractionated radiation. The mechanisms underlying this differential response, however, are still unknown.
Aiming to fill this gap in knowledge, researchers in Germany have proposed and investigated a chemical mechanism to describe the efficacy of mini-beams and micro-beams. They performed a simulation study to find a surrogate to the tumour control seen in MBRT. Building on a proposed correlation between tissue damage and the level of reactive oxygen species (ROS) in tissue, the team examined whether the distribution of a radiation-induced molecule or radical could provide such a surrogate.
“From all published animal studies with micro- and mini-beams, it was clear that dose coverage of the tumour in the valley region was too low to allow any form of tumour control. So the dose delivered to the tumour was not a good surrogate for establishing the biological effect,” explains senior author Joao Seco from DKFZ. “Several years ago, my group started working in radiochemistry, with the focus of evaluating which radical or molecule could be a good surrogate of biological effect.”
In a study described in Frontiers in Physics, Seco and colleagues investigated 12 potential generic radicals and molecules (gRMs) produced by a radiation beam. As physical dose coverage is not achieved in MBRT, they hypothesized that biological damage is instead provided by the distribution of such a gRM reaching a uniform coverage of the tumour target.
As such, they proposed that a candidate gRM must meet four conditions: it should be stable enough to diffuse during beam-on to cover the dose-valley regions; it should reach a steady state in production versus removal, within a few microseconds; it should be a product of water radiolysis; and it should have oxidizing capacity to create cellular damage.
The researchers, also from Heidelberg University and GSI, used the Monte Carlo code TRAX-CHEM to model the production, removal and diffusion of the 12 gRMs. The simulations revealed that the steady state was only reached by three of the gRMs, with only one of these – hydrogen peroxide (H 2 O 2 ) – an oxidizing species. Thus they restricted all further analysis to H 2 O 2 .
Two-dimensional representation of the temporal diffusion of molecules and radicals produced by a proton beam, simulated with TRAX-CHEM. (Courtesy: CC BY 4.0/Front. Phys. 10.3389/fphy.2020.564836)
To assess the potential of H 2 O 2 as a candidate for the biological efficacy of MBRT, the researchers evaluated their simulations against previous animal experiments. One limitation of TRAX-CHEM is that it only runs up to 10-6 s. So to extend their predictions to times suitable for experimental comparison (up to 103 s), they modelled the time evolution of H 2 O 2 with a convolution model that uses a Gaussian Kernel (calculated from TRAX-CHEM) to convert delivered dose into H 2 O 2 spatial distribution at a specified time.
They calculated the H 2 O 2 spatial distribution for four proton mini-beam and photon micro-beam studies, using the published values of peak spacing, peak FWHM and peak-to-valley dose ratio (PVDR). Based on these parameters, they calculated the beam-on time at which the H 2 O 2 distribution reached a uniform tumour coverage.
Comparisons with the actual irradiation times revealed that the calculated minimum irradiation times were reached in three of the four experiments. In these cases, the predicted H 2 O 2 distribution had a coverage of at least 95%. The team notes that these three experiments were all associated with high probabilities of tumour ablation or growth delay.
Prediction of the minimum beam-on time required to achieve uniform H 2 O 2 coverage for two synchrotron experiments. (Courtesy: CC BY 4.0/Front. Phys. 10.3389/fphy.2020.564836)
In the experiment that did not reach the minimum beam-on time, the model predicted that H 2 O 2 did not uniformly cover the target. In this experiment (which used synchrotron-generated X-ray microbeams), only two tumours were ablated in 32 irradiated rats. In contrast, an experiment using the same synchrotron beams but with smaller spacing, in which H 2 O 2 diffused uniformly over the target, produced five tumour ablations out of 11 rats.
The researchers surmise therefore that homogeneous H 2 O 2 distribution is a highly relevant parameter for tumour ablation and should be further investigated. The fact that this uniform coverage may be generated in the tumour but not in normal tissue, combined with the higher tolerance of normal cells to ROS relative to cancer cells, may underlie the differential effect between tumour and normal tissue in MBRT.
Seco notes that the developed model can be used to assess whether MBRT will provide uniform H 2 O 2 coverage of the tumour volume. There is still a need, however, to investigate the correlation between this coverage and treatment response. The team is looking to discuss with other groups a possible animal study to understand how H 2 O 2 could be used to quantify treatment response.
“In our study, we demonstrated that we should use H 2 O 2 – not dose – as a marker of biological effect for micro- and mini-beam radiotherapy,” Seco concludes.