From the network that brought us Game of Thrones, HBO has found another winner with its hit mini-series Chernobyl. The five-episode show, which finished in June, told the story of the 1986 accident at the nuclear-power plant near Pripyat, Ukraine, and those who responded to it. While the dramatization of the tragedy is entertaining and has received rave reviews, the show also repeats various urban myths and exaggerations about the effects of radiation. This misrepresentation risks feeding an inflated fear of nuclear energy, which may have fatal consequences.
Of course, Chernobyl is not a documentary and it is wishful thinking to expect every historical drama on TV to follow the truth to the letter, especially when twisting it just a little makes for a more thrilling story. But there are many instances in this particular drama that take artistic licence to the limit, from wild exaggerations to purely fictional events.
For example, at the end of the first episode, residents of Pripyat gather on a railway bridge to watch the reactor fire on the night of the accident. The ominous black screen at the end of the episode suggests that nobody on the bridge survived. Yet there is no reliable record that this incident ever happened or that these deaths even occurred. Meanwhile, the helicopter crash shown in episode two is a misrepresentation of the truth – although a helicopter did crash several weeks into the core cooling operation, this was because of a collision with a crane rather than due to a noxious cloud of radioactive smoke.
The scale of the accident in the series is also vastly inflated, from the amount of radiation released to the number of people who were killed. The explosion, which could supposedly have left “much of Europe uninhabitable”, was quoted as being an incredible four megatonnes – a magnitude that would have been impossible given that a nuclear-power station physically cannot explode in the manner of a nuclear bomb.
The exact number of deaths caused by Chernobyl is also conspicuously missing from the programme. Instead, viewers are left with the impression that any characters who do not reappear on screen have inevitably died horrible deaths. In fact, over 80% of first responders survived, while reports by the World Health Organization estimate that the number of deaths caused by Chernobyl over an 80-year lifetime is around 4000 – comparable to the average number of people killed in road crashes every day globally.
Fearing the invisible
The problem with shows like Chernobyl is that they show only the hazards of nuclear energy and none of its advantages. When combined with the repetition of false, sensationalized nuclear-horror stories, is it any wonder people have trouble distinguishing where the line falls between fact and fiction? This misrepresentation of nuclear power is frightening and insidious, and leads to deadly consequences in both the immediate future and the long term.
Indeed, directly after the Chernobyl accident there was a rise in abortions due to fear of the effects of radiation on an unborn child, even in countries far away from the site where the increase in radiation exposure was minimal. Researchers estimate between 50,000 and 200,000 otherwise wanted pregnancies were terminated based on uninformed panic with no real scientific evidence. In Denmark, which saw a marked increase in the number of abortions, terminations were performed for women who had been exposed to an average effective dose of just 17 μSv – less than you would expect to receive from one transatlantic flight.
Even with improvements in nuclear safety and education since 1986, we still see this fear-driven behaviour around radiation today. The overly cautious evacuation after the Fukushima nuclear accident in Japan in 2011 was responsible for more than 1000 deaths, according to a report by the Fukushima Prefecture government, while there have still been no radiation-related fatalities. Studies have now determined that fewer people would have died (from exposure to radiation) if they had been allowed to remain in their homes, instead of being subjected to the stresses and dangers of a large-scale evacuation.
Worryingly, the long-term consequences of the public misunderstanding of radiation may be far more damaging. Nuclear power has the lowest number of deaths per kilowatt-hour of electricity generated – even when compared to renewables. Even taking worst-case scenario figures from accidents such as Chernobyl and Fukushima into account, nuclear power remains the safest form of energy. Part of this is because nuclear power produces very little carbon dioxide, resulting in fewer deaths from air pollution and the consequences of climate change. The lack of enthusiasm for building more nuclear power stations means we are missing the opportunity to save thousands, if not millions, of lives every year by the reduction of air pollution alone.
With the necessity of phasing out fossil fuels and meeting ambitious emissions targets becoming ever more urgent, taking the nuclear option off the table might be the worst mistake we could make. But if the fearmongering and misapprehensions around radiation are not addressed, the consequences will be more unnecessarily conservative and overly cautious approaches to nuclear power that stem from fantasy rather than actual science. We have reached a point where serious decisions must be made about the future of our energy supply. Whatever these decisions are regarding nuclear power’s place in the global energy mix, they must be made from a position of understanding, not of uninformed fear.
The exaggerated portrayal of the dangers of radiation may make Chernobyl gripping to watch but the real horror of sensationalized accounts like this is that their potential for fuelling lasting public fear may, in the long run, cause more deaths than the radiation they portray.
Better brain imaging or even drug delivery could be possible thanks to researchers at the Polytechnic University of Valencia in Spain. They have developed a technique for 3D printing holographic lenses that focus ultrasonic sound waves in the brain.
Penetrating the skull
Ultrasound, an acoustic wave with frequencies greater than those audible to humans, is widely used in diagnostics and for imaging soft tissue, such as a developing fetus. Furthermore, it can be used as a non-invasive therapeutic technique, which operates by focusing high intensity waves to ablate fibroids or destroy cancerous tissue. In the case of the brain, however, this method is challenging because the skull blocks and distorts the ultrasound, preventing it from focusing on brain tissue.
Previously scientists have tried using phased arrays to control the incoming ultrasound to correct for aberrations on penetrating the skull but these have limited numbers of pixels and can be quite costly. Led by Noé Jiménez the Polytechnic University of Valencia researchers have now 3D printed a lens that can generate complex patterns to help refocus the beam upon penetrating the skull, allowing it to effectively target brain regions such as the hippocampus, and image more clearly.
Making waves
The lenses comprise of a block of plastic with varying voxel sizes. Each voxel diffracts the ultrasonic wave in a slightly different way. The interference of these waves creates a hologram as they focus onto a 3D target volume within the brain.
Testing the invention
Jimènez and colleagues used a four-step process to test out their approach. Firstly, they extracted the geometry and acoustic properties of the human skull using open source X-ray images from computerized axial tomography (CAT) scans. They then also examined soft tissue information from the brain itself, using data from magnetic resonance imaging (MRI). This allowed them to produce a computer model of the patient’s skull and brain.
Diagram showing the holographic lens focusing over the right hippocampus. Credit: S. Jiménez-Gambín et al., Phys. Rev. Applied (2019)
Following this step, the team devised a method to bend ultrasonic waves inside the skull. They used three different types of holographic focusing, with increasing complexity: one that focuses the waves to a point, another that results in a curved wave path and a third that guides the waves to flood the whole of the right hippocampus in the brain.
Next, the scientists modelled the sound waves required to create an ultrasonic hologram within the brain. By back propagating virtual acoustic fields in the brain to a point outside the skull they could calculate the phase and amplitude of the source waves needed and design a lens to produce them.
Finally, using the previously acquired CAT scan and MRI data, they manufactured a 3D printed skull phantom (a realistic brain replica), which they used to test the holographic lens. The data they obtained from the skull phantom showed good agreement with theory and simulations.
Impact
Despite the good fit between the experimental data and theory and simulations, differences did arise due to the disparity in density between the printed material and bone. However, the researchers show by using full-wave simulations, that the same ultrasonic focusing would still be possible in a realistic situation.
This new concept will hopefully lead to low cost therapy, imaging of the central nervous system or even ultrasound-triggered neuromodulation. Perhaps, most importantly, it could also have implications for new drug delivery techniques. For example, it has the potential to open the blood-brain barrier, which typically blocks therapeutic drugs in the treatment of Alzheimer’s disease.
When it comes to weather disasters, the biggest killers in the US are extreme heat and cold. Many people rely on air-conditioning to keep them cool but this dependency could be dangerous if a power cut coincides with hot weather. Residential buildings in many US cities are highly vulnerable to such heat disasters, according to a new study, and that danger will become greater as climate changes.
Over 85% of homes in the US have some form of air-conditioning installed and almost all new-builds come with air-conditioning as standard. Historically, homes used passive strategies like natural ventilation and thick stone walls to keep cool. The advent of inexpensive and widely available air-conditioning means that modern houses are free from the design constraints of traditional cooling solutions but many Americans now depend heavily on air-conditioning.
“Modern buildings tend to have very little thermal mass, and as a result respond fairly quickly to outdoor [high temperature] forcing when their air-conditioning systems are not operational,” explains David Sailor of Arizona State University.
When air-conditioning fails the consequences can be fatal. For example, the power outage caused by Hurricane Irma in summer 2017 resulted in the deaths of eight people at an assisted living facility in Florida from exposure to high indoor temperatures. Despite ongoing improvements in the resilience of power infrastructure, it is expected that the risk of major power outages will increase, particularly as extreme weather events such as hurricanes and heatwaves become more frequent and severe.
Sailor and colleagues used whole-building energy simulations to study the impact of loss of air-conditioning combined with a hot weather episode in the 20 largest metropolitan areas in the US. In half the simulated locations the researchers found that conditions inside buildings would exceed the overheating threshold in five to seven hours. This means a prolonged power outage starting early in the day would cause stifling indoor temperatures overnight: a critical exposure time as most people remain indoors.
Nine major US cities – Miami, Houston, Tampa, St Louis, Dallas, Chicago, Phoenix, Philadelphia and Atlanta – with a combined population of 52 million people had buildings that could overheat in less than seven hours and remain overheated for at least 40% of a three-day-long hot period. Many of these cities are also humid.
“People in these cities rely on air-conditioning, and a major power outage could have devastating consequences,” says Sailor.
Many of the newer, more energy-efficient buildings do not have better resiliency to heat. The more stringent insulation requirements and resulting air-tightness can make it harder for the building to “lose” heat at night.
“In cities that experience heat waves during the daytime but cool off substantially at night we need to ensure that buildings can take advantage of the night-time ‘free’ cooling via opening windows, for example,” says Sailor.
There are other ways to improve matters too. For starters, switching to energy-efficient appliances and lighting helps reduce the amount of heat produced indoors. Meanwhile, buildings in air-conditioning-dominated climates can be made more resilient with the use of new smart materials and exterior coatings, which reflect incoming solar energy and emit heat stored in the materials.
“These materials make the building much more resilient to extreme heat and also substantially reduce air-conditioning bills under normal operations,” explains Sailor. Incorporating thermally massive materials such as brick and concrete into new buildings can help mediate big temperature swings.
The risk of heat disasters will increase as climate changes and in urban areas will be amplified by the urban heat island effect. Sailor and colleagues say that designers should be encouraged or required to investigate how their buildings will respond to air-conditioning failure during a heatwave, and to meet a maximum allowable rate of indoor warming. And the researchers suggest that better guidelines are needed for climate-sensitive design in general.
Officials at the Thirty Meter Telescope (TMT) have indicated they will seek a building permit to construct the giant telescope on the island of La Palma, belonging to Spain’s Canary Islands. While Mauna Kea in Hawaii remains the preferred site for the TMT, the continuing protests on the island are forcing officials to proceed with the legal requirements to build the observatory elsewhere.
Designed to have a primary mirror 30 m across made of 492 hexagonal segments enclosed in a structure 66 m wide and 56 m tall, when built the TMT will allow astronomers to resolve the faintest and oldest galaxies. The TMT board had chosen Mauna Kea, which already hosts 13 other telescopes, as the observatory’s site in July 2009. Since then, the organization has received a series of necessary approvals and permits (see timeline below).
Our position is that we are here if the TMT project needs us
Rafael Rebolo
However, native Hawaiians, who regard the Mauna Kea summit as sacred – and who had previously objected to the growth in the number of telescopes there – have protested against the telescope’s construction. Last month, when the TMT was again allowed to proceed towards construction, protesters blocked access roads to the mountain leading to arrests by police. Hawaii’s Department of Land and Natural Resources then granted a two-year extension to the deadline for starting construction, which is now set at 26 September 2021.
Support at ‘all levels’
Since 2016, the TMT Organisation has been studying alternative sites for the TMT should Mauna Kea not be a viable option and later that same year it selected the Observatorio del Roque de los Muchachos in La Palma as its preferred alternative site. In April 2018, TMT officials then postponed a final site decision to wait for “further progress in the legal process”.
Rafael Rebolo, director of the Canary Islands Astrophysics Institute, has told the Associated Press that he has received a letter from the head of the Thirty Meter Telescope project saying that its board has now decided “to proceed with the request to seek a building permit” for La Palma. “We are observing what is happening in Hawaii with the maximum respect,” Rebolo told AP. “Our position is that we are here if the TMT project needs us.”
In a statement yesterday, TMT executive director Ed Stone notes that Mauna Kea remains the “preferred site” for the TMT. “We continue to follow the process to allow for TMT to be constructed at the site in La Palma should it not be possible to build in Hawaii,” he says. “This process has been ongoing since 2016.”
Given that the project has the strong backing from government officials in Spain, the permit would face little resistance. Indeed, Spain’s science minister, Pedro Duque, last month issued his support. “We maintain the capacity and the goodwill of all the authorities and at all levels in the Spanish state so that if there is a decision to bring the telescope to the Canaries, [we] are all aligned in order to receive this telescope,” he stated on 30 July. “We have all the necessary plans at all levels, the people, the speed, the systems, absolutely everything is ready if they want to come.”
The possibility of relocating the TMT away from Mauna Kea has concerned some astronomers who think that La Palma’s environmental conditions will limit the telescope’s scientific potential. In particular, the warmer climate and lower elevation of La Palma compared to Mauna Kea will affect mid-infrared observations, which require dry, cool conditions. Such measurements are used, for example, to characterize nearby exoplanets and their atmospheres, and losing that ability would almost eradicate the exoplanet programme from the TMT’s science goals.
Yet, if the TMT is built at La Palma, then officials hope that the loss of sensitivity would be mitigated in part by adaptive optics and by carefully scheduling observations so that those requiring high infrared sensitivity can be on the clearest nights.
Timeline: ups and down of the Thirty Meter Telescope
2004 Project office for the $1bn Thirty Meter Telescope (TMT) is established
2007 The Gordon and Betty Moore Foundation pledges $200m to the TMT
2009 Mauna Kea in Hawaii is selected as the site for the TMT
2013 Hawaiian environmental officials give permission for the construction of the TMT
2014 Construction of the TMT begins following the approval of a sublease by the Hawaii Board of Land and Natural Resources (BLNR)
2015 Construction is halted after protests by native Hawaiians.
2016 Hawaii’s Supreme Court rules that the construction permit for the TMT is invalid while TMT officials choose the Canary Islands as an alternative site for the planned telescope if construction does not go ahead in Hawaii
2017 The BLNR grants a construction permit for the TMT following the recommendation by a senior judge
2018 Hawaii’s Supreme Court rules that construction of the TMT can begin
2019 Hawaii’s Department of Land and Natural Resources issues the TMT with a formal “notice to proceed”, but construction fails to begin following more protests. Officials grant a two-year extension to the deadline for starting construction.
FLASH radiotherapy – it’s the technique that’s got everyone talking. The idea is that delivering radiation at ultrahigh dose rates, roughly 50 Gy/s and above, will vastly reduce normal tissue toxicity while preserving anti-tumour activity.
The premise has been demonstrated in preclinical studies by several research groups and, as delegates at the recent AAPM Annual Meeting heard, the first human treatment has just taken place. A dedicated symposium examining the promise of FLASH saw a ballroom packed full of delegates keen to find out more about this cutting-edge treatment.
A giant leap
The first speaker was Julianne Pollard-Larkin from MD Anderson Cancer Center, who presented a talk entitled “FLASH Photon: one small step for physics, one huge leap for cancer therapy”.
Pollard-Larkin began by citing a 2018 study highlighting that mice receiving thoracic irradiation at 3600 Gy/min had 70% less pulmonary fibrosis than those treated with conventional radiotherapy at 1.8 Gy/min. “Ultrahigh dose rates showed a marked reduction in fibrosis at every time point investigated,” she told the audience. “I could stop my talk now…”
But she didn’t. Instead, she presented a brief history of the FLASH effect, which was first noted in some form as far back as 1959. In 1971, researchers showed that high dose rate electron beams induced hypoxia. And in 2014, a report revealed the differential response to high dose rates between normal and tumour tissue in mice. “In 2014, it was reborn and rebranded as FLASH radiotherapy,” said Pollard-Larkin.
She described several studies demonstrating the advantages of FLASH over conventional radiotherapy. One early investigation of mice with lung tumours showed that FLASH spared normal lung and was toxic to tumours, with “almost no double-edged sword”, while another showed memory sparing in mice after whole-brain irradiation. In larger mammals, FLASH increased progression-free survival of six cats with naturally occurring nasal tumours, and conferred a protective effect on irradiated skin of mini-pigs.
So how is FLASH actually delivered? Several of the preclinical studies used the Oriatron eRT6 from PMB-Alcen, an experimental high dose‐per‐pulse linac that delivers an electron beam with dose rates of up to 200 Gy/s.
But not everyone has an Oriatron, so Pollard-Larkin described how she adapted a redundant linac to deliver FLASH. “We had an old decommissioned linac and they allowed me to work with this,” she explained. Adaptation included removing safety systems, tuning the 20 MeV board and creating a holder for a miniature ion chamber and film. The measured output ranged between 40 and 60 Gy/s over time. “Get a linac that nobody cares about and you can do it too,” she told the audience.
As for how FLASH actually works, the biology is inevitably complex and various ideas have been proposed. One possibility is that the ultrahigh dose rate irradiation converts the endogenous oxygen in all tissues into reactive organic species, which normal tissues can remove more effectively than tumours. Another suggestion is that FLASH causes transient hypoxia and preferentially spares normal tissues due to differential oxygen tensions between tumour and normal tissues.
And while researchers strive to unravel the exact mechanisms underlying FLASH, work continues alongside to implement clinical translation. One challenge is the lack of available systems to perform FLASH. Pollard-Larkin noted that treatment of deep tumours will require very-high-energy electrons, or X-ray or proton FLASH. “We also need to come up with a comprehensive dose monitoring system,” she added. “Safety is really critical when you are delivering such high dose rates.”
Pollard-Larkin concluded by emphasizing FLASH’s potential, particularly its 30–80% protective effect. “FLASH treatment times are economical and beneficial to clinics, especially those in low- and middle-income countries,” she explained. “And the reduced number of fractions necessary could provide better quality-of-life for patients. I see FLASH as one of the cancer breakthroughs of 2020 that we need to work on as a community and push through.”
FLASH for protons
Lei Dong from the University of Pennsylvania followed with a look at FLASH using proton beams, which could provide an option for treating deep-seated tumours. He pointed out that in pencil-beam scanning proton therapy, the dose is packed into a tight spot and thus already has a relatively high dose rate.
He examined the requirements to achieve ultrahigh dose rates required for such a proton therapy system. For a typical 200 MeV pencil beam spot of 1 cm diameter, he estimated that 22 nA at the nozzle would create a dose rate of 100 Gy/s. However, the need for beam propagation and creating a 5 x 5 cm field, for example, ups this requirement to about 600 nA at the nozzle to create 100 Gy/s.
Dong described the current status of proton FLASH research at various proton therapy facilities. Researchers at Institut Curie in France, for example, have adapted a clinical system to perform proton FLASH irradiation of small animals. They optimized a single scattering system with a ridge filter and a high current monitoring system. For a 12 × 12 mm field, the set-up achieved dose rates exceeding 40 Gy/s at energies between 138 and 198 MeV.
At Penn, Dong and colleagues are using an image-guided small-animal X-ray irradiation coupled to a proton beamline to study proton FLASH with mice. They performed whole-body irradiation at 1 or 75 Gy/s, delivering a 7.5 Gy dose. “We see that FLASH produces better survival compared with conventional irradiation – an indicator of the normal tissue sparing,” Dong explained. He notes that, due to the high dose rates of their set-up, dosimetry with a parallel plate chamber is preferable to a cylindrical ionization chamber.
The Penn research team with the SARRP-on-rails. (Courtesy: Eric Diffenderfer)
A team at the University of Maryland performed a similar study comparing 1 and 40 Gy/s thoracic irradiation in mice. They saw a 30% reduction in lung fibrosis, reduced skin dermatitis and an increase in overall survival.
Dong also shared a slide showing proton FLASH outcomes in human studies. This one was blank… for now. So how could proton FLASH be implemented clinically? He pointed out that, for starters, extra room shielding might be needed – with high-energy beams to maximize ultrahigh dose rates, the protons may not stop inside the patient. On the plus side, this eliminates the issue of range uncertainty. “In proton therapy we would never have imagined having no need to worry about range uncertainty!” he said.
Dong concluded by reiterating that proton FLASH demonstrates significant normal tissue sparing in animal studies, though the biological effects are still unclear. Dose rate will become an important quality assurance issue, while treatment planning will need to incorporate machine delivery information, he explained.
Into the clinic?
Finally, Billy W Loo Jr from Stanford University School of Medicine took a look at the clinical translation of FLASH. He first described some of the preclinical work performed at Stanford, in which the team customized a clinical linac to use the electron beam at high currents and without a photon conversion target.
They employed the reconfigured system, which could deliver dose rates of 0.1–300 Gy/s, to perform whole-brain irradiation on mice and examine cognitive sparing after FLASH. “Like other groups, we found that FLASH produces a similar neurocognitive outcome to unirradiated controls, while a clear detriment was seen with conventional irradiation,” Loo explained.
He also described work investigating total abdomen irradiation with 16 MeV FLASH electrons. “In normal mice, we saw a loss of gastro-intestinal function using a conventional dose rate; but this function was preserved after FLASH.” In tumour-bearing mice, both dose rates produced similar levels of tumour reduction. As for late effects, one year after abdominal irradiation using a non-lethal dose, two conventionally treated mice developed radiation-induced cancers, while none of the FLASH group did.
In a further study, the team noted a decreased incidence of spontaneous lung metastases after FLASH irradiation of subcutaneous tumours, suggesting a possible immune effect at distant sites and leading Loo to propose the possibility of a “FLASHscopal” effect.
Next, Loo moved onto the headline act: the first case report of FLASH radiotherapy in a human patient. Published by researchers at Lausanne University Hospital a few days before the AAPM meeting, the paper described treatment of a 75-year-old man with widely spread cutaneous T-cell lymphoma. The patient had undergone over 110 localized radiotherapy courses for different lesions over the past decade, with good tumour control but severe skin toxicity.
In this study, the team treated a 3.5-cm wide ulcerated lesion, using an Oriatron linac to deliver 15 Gy in 90 ms. Notably, the patient felt no sensation during treatment. At day 15, the tumour was healing; optical coherence tomography showed some thickening at the skin surface in the treated region, but no breakdown at the dermis–epidermis interface. Five months later, the patient’s tumour was completely healed with no toxicity.
“These results are very intriguing,” said Loo. “This is suggestive, though not conclusive, of a FLASH effect in a human patient and certainly a demonstration of clinical feasibility of delivering FLASH.”
The study also demonstrated the technical feasibility of delivering FLASH to patients using an existing preclinical system. Loo noted that while electron beams can treat superficial targets and proton pencil beams can treat small volumes, “I argue that new technology is needed for FLASH to target general cancer patients.”
Loo pointed out that the fastest radiotherapy treatment today takes just over three minutes to deliver 25 Gy, which is extremely fast, but still a long time compared with the motion of a tumour. “The ultimate motion management strategy is to freeze all motion,” he said.
Conceptual rendering of the PHASER system. (Courtesy: Radiother. Oncol. 10.1016/j.radonc.2019.05.005)
With this aim, Loo and colleagues are developing the PHASER linac, a compact, power efficient radiation delivery system that can treat in a fraction of a second – three hundred times faster than SABR and fast enough to freeze motion. “This would be a platform for translating FLASH to the clinic”, he said. “It’s the first fundamentally new linac design in 60 years.”
Restrictions on US work visas may be deterring foreign-born science and engineering PhDs from taking jobs at technology start-ups, depriving new companies of scarce talent. That is the conclusion of researchers at Cornell University and the University of California, San Diego, whose survey of STEM PhD recipients at US universities found that foreign PhDs were 56% less likely than their US peers to accept a job at a start-up, despite expressing more interest in start-ups when they were students and being just as likely to apply to and receive job offers from them.
Michael Roach and John Skrentny based their conclusions on a survey of 2324 people who earned PhDs in STEM subjects from US universities between 2010 and 2016 and subsequently took jobs in industrial research and development. Overall, 15.8% of US PhDs in their sample went to work at start-ups, compared to 6.8% of foreign PhDs. Within physics, the figures were 15.2% for US citizens and 10.9% for people classed as international students, who must obtain employment-based visas if they wish to work in the US after their student visas expire.
In their paper (PNAS10.1073/pnas/1820079116) Roach and Skrentny point out that larger firms are more likely to have the resources to apply for work visas under the US H-1B programme. The application process for these visas can take several months and cost up to $10 000 in attorney and filing fees, and their numbers are subject to restrictive annual quotas. Because of these hurdles, the researchers speculate that foreign PhDs may avoid taking jobs at start-ups out of concern that their employers will not be able to obtain a work visa, or that they might lose their eligibility to work in the US if the start-up fails. The result, they argue, is that start-ups find it “difficult to attract the talent that they need to innovate and compete against large firms”.
For physics-based start-ups, the competition is acute: more than 40% of the people who earned physics PhDs from US universities between 2010 and 2015 were foreigners without permanent residency. “If you’re a start-up founder and you’re trying to hire somebody with the latest training in quantum computing, there may be only five researchers on the market at a given time, and three of them are foreign-born,” Roach tells Physics World. “It might be that the foreign-born ones wouldn’t even come to work for you if there’s some uncertainty level [about getting a visa].”
Despite these successes, however, the demographics inside physics classrooms and laboratories have not improved. In the UK in 1986 girls made up 23.1% of the physics A-level cohort, but only 22.2% in 2018. Indeed, in 2018 women made up 57.5% of all undergraduate students in the UK, but only 22.2% of physics undergraduates – and only 1.7% of all physics undergraduate students were black women. In a 2018 study, Luke Holman at the University of Melbourne in Australia and colleagues predicted we are 258 years from gender parity in authorship of peer-reviewed physics publications (PLOS Biol.16 e2004956).
(Courtesy: Jesse Karjalainen/Institute of Physics)
The consequences
The lack of diversity in physics is not only an issue of inequality; it affects the physics we do and the systems we create.
In the UK, the House of Commons Science and Technology Select Committee exists “to ensure that government policy and decision-making are based on good scientific and engineering advice and evidence”. But when the committee announced its new membership in 2017, it was 100% men – potentially giving the impression that the opinions of women, who make up half the population, were not as important. In response to the resulting public outcry, the committee appointed three women, including a mathematician (Vicky Ford MP) and a physicist (Carol Monaghan MP).
Women’s underrepresentation in science also has serious consequences for how research is conducted and applied. When women, and particularly those from further marginalized backgrounds, are not afforded a seat at the table, they cannot correct for the biases that are incorporated into experimental design and downstream application. For example, Joy Buolamwini, a researcher in the Media Lab at the Massachusetts Institute of Technology (MIT), has demonstrated that facial recognition technology is biased against women and people of colour due to inadequacies in the datasets (Proceedings of Machine Learning Research81 77). Women have also been underrepresented or outright neglected as subjects in health research, which can have life-threatening repercussions. A lack of understanding of how health problems progress in women’s bodies can result in misdiagnosis of, for instance, heart attacks, and incorrect dosages of medicines meant to prevent or treat disease. Additionally, women’s pain has often been dismissed by the medical profession, due in large part to implicit biases that see women as the weaker gender, a phenomenon known as the “gender pain gap”.
Physics will fail to achieve its maximum potential as long as the gender gap – and similar inequities – persists.
An unfair beginning
This lack of representation is often attributed to the myth that girls and women are intrinsically less well suited to science, technology, engineering and mathematics (STEM). Indeed, the “greater male variability hypothesis” is routinely used to explain the overrepresentation of men. This hypothesis puts forward the idea that there is a greater variability in men’s aptitude for science, which means there are men both outperforming and underperforming women. In other words, while some men will underperform women, there are more exceptionally high-performing men compared with women who exceed the performance threshold for academic success.
Multiple studies have debunked that idea, including a 2018 study of 1.6 million students from 268 high schools around the world (Nature Comms9 3777). Although it found that girls’ academic performance in STEM subjects was less variable than boys’ – on the face of it supporting the theory – the study demonstrated that, on average, girls received slightly better STEM grades than boys, and that the variance of grades was less than in non-STEM subjects. This finding therefore implies that the variability hypothesis is insufficient to explain the lack of gender diversity in STEM. Furthermore, in the UK, girls actually achieve higher grades in their physics GCSEs (usually taken at the age of 16) than boys, but are considerably less likely to choose it for A-level (taken at 18). According to the Improving Gender Balance project from the Institute of Physics (IOP), which publishes Physics World, the gender gap in physics is not due to aptitude or interest. While girls have long outperformed boys at GCSE maths and physics, they lack the confidence to take it for A-level. Girls and women are discouraged from pursuing physics due to the gender stereotypes and unconscious bias they experience in school and society.
Stereotypes of how science is done present an additional barrier to entry. Physics is often portrayed as a solitary endeavour; the occupation of lone, socially awkward geniuses with little understanding of the real world. Of course, this paints a false picture of how physics is done, which is namely through active collaboration and globally co-ordinated efforts. The public image of physics fundamentally misrepresents the role science has in our society – how it furthers our understanding of the world, how the application of fundamental research improves lives, and how it allows us to gather evidence to craft interventions that will sustain our planet. Changing how the process and purpose of science is represented can therefore be effective in attracting communally oriented individuals, regardless of gender.
(Courtesy: Hopper Stone/Levantine/Kobal/Shutterstock)Role models: The 2016 film Hidden Figures starred Janelle Monáe as Mary Jackson (top) and Taraji P Henson as Katherine Johnson (bottom) – real women who worked as an engineer and mathematician, respectively, at NASA from the 1950s onward. (Courtesy: Hopper Stone/Levantine/Kobal/Shutterstock)
Representation of women scientists in the media also plays an important role in shaping girls’ and women’s ideas of what they can be. The 2016 film Hidden Figures, which follows the true stories of three black women mathematicians at NASA, broke box-office records and catalysed STEM education initiatives aimed at increasing the representation of women of colour. Nevertheless, women continue to be underrepresented in mainstream media. Only 19% of children’s books feature a girl as the main character, and less than 1% are led by a character who is a person of colour. According to a 2018 report, women scientists only account for one-third of STEM characters in film, television and streaming today; and when they are on screen, more often than not those characters are white.
Lack of recognition of women’s notability extends beyond the media. Women make up only 17.8% of biographies on Wikipedia, 20% of people on UK banknotes (0% in the US) and 21% of people in UK statues (8% in the US). The absence of women on screen, on air, in print and online further perpetuates the idea that women have not made significant contributions to society, which could not be further from the truth.
Since the beginning of 2018, we have been mass-editing Wikipedia to create and improve the biographies of women scientists and engineers. We have hosted “edit-a-thons” at conferences, including the annual meeting of the American Physical Society, as well as in high schools and universities. Between us we have so far written about 700 biographies of people who might otherwise have been overlooked.
Systematic inequality
If you’ve ever considered the underrepresentation of women in senior science positions, you will probably have heard of the “leaky pipeline”. This model, which is cited in more than 10,000 academic articles, is routinely used to explain the lack of women at the top. According to the leaky-pipeline model, when the going gets tough, the women leave. Not only does the model ignore the important role scientists have outside academia, it doesn’t tell the whole story: women aren’t failing at science, science is failing them. The pipeline isn’t leaking. Instead, it’s littered with holes by design.
Progression through the academic pipeline depends on several metrics: the amount of funding you bring in, the number of papers you publish and the evaluation of the classes you teach, all of which have been shown to favour men. Whether it is at high school or university (Phys. Rev. Phys. Educ. Res.12 020107), student evaluations favour male academics, particularly native English speakers, even when women teach exactly the same course (PLOS ONE14 e0216241). Women academics are less likely to be asked to be involved with peer review (Nature561 295), less likely to have their papers accepted and less likely to be cited than their male colleagues (Socius 10.1177/2378023117738903).
After concern about unconscious bias creeping into the judgment of scientific proposals, the Irish Research Council anonymized its application process, and ended up with women outperforming men. Nevertheless, anonymization remains uncommon despite being a relatively simple approach to mitigate gender bias in assessment.
While women are discriminated against in the allocation of research funding, they take on a disproportionate amount of academic “service roles” – such as administration and teaching – which require a great deal of time and energy. These service roles can increase the appeal of a given academic institution and are vital for improving the workplace culture, but they often go unrecognized and unrewarded in promotion criteria. Women and people of colour are also routinely omitted from the nominee pool for scientific awards (Nature565 287). Such recognition can have a significant impact on a scientist’s career: improving their self-concept, future prospects and how they are treated by their home institution. It is interesting to note that, while underrepresented in prestigious science awards on the merits of research, women are overrepresented in awards for advocacy and teaching, perhaps because service roles are often coded as “women’s work”. Certainly, the structures within the academic pipeline seem to benefit and praise certain groups while further marginalizing others.
Sexual and gender harassment
The power imbalances of academia and culture of silence can result in bad behaviour that goes unchecked. A recent survey of 455 US undergraduate women physicists revealed that 74.3% had experienced sexual harassment (Phys. Rev. Phys. Educ. Res.15 010121). The US National Academy of Sciences (NAS) found that two-fifths of postgraduates and half of medical students had experienced sexual harassment. Scientific societies such as the American Geophysical Union and the NAS are beginning to develop policies that equate sexual harassment with scientific misconduct and oust known harassers from their membership.
The power imbalances of academia and culture of silence can result in bad behaviour that goes unchecked
While the US has legislation that prohibits sexual harassment at government-funded education institutions, which is known as Title IX of the Education Amendments Act, legislation in the UK isn’t always so clear. In a survey of almost 2000 students, the UK-based organization The 1752 Group reported that sexual harassment of students by university academics is “rife”, but with no clear policies in place, it is rarely reported and often silenced. Indeed, the BBC used a Freedom of Information request to identify that UK universities spent £87m on pay-offs with non-disclosure agreements between 2017 and 2019. Science has done little to support whistleblowers. BethAnn McLaughlin – a neuroscientist who founded the nonprofit #MeTooSTEM to shed light on the harassment of women in academic science – has lost her tenure because of her activism. Meredith Whittaker, a computer scientist and expert on artificial intelligence, led the Google Walkout to challenge mishandling of claims of sexual harassment, and consequently faced retaliation from her employer for speaking up. In July 2019, she left Google to work full-time at New York University’s AI Now Institute, which Whittaker co-founded and focuses on ethical questions surrounding AI.
Best practice
Intersectionality was coined by Kimberlé Williams Crenshaw – a civil rights activist and scholar of critical race theory – in 1989. It recognizes the various social categorizations that apply to an individual and can contribute to “overlapping systems of privilege and oppression”. To achieve true gender equity, we must therefore recognize that not all women have the same experience, and that women of colour, in the LGBTQ+ community, with disabilities, or from other marginalized backgrounds face different forms of discrimination that must be addressed.
Considering an intersectional framework is essential for institutions to work towards improving the gender balance, and to ensure that their initiatives and policy interventions maximize equity. A growing body of research shows that initiatives geared towards women tend to advance white women at the expense of women of colour. As a result, a “one size fits all” approach to advancing women in STEM is insufficient to enjoy the full benefits that diversity and inclusion bring to science.
Unfortunately, diversity campaigns rarely have any impact, can result in illusions of fairness, and – at their worst – trigger poorer behaviour toward women and other underrepresented groups. There are several reasons for this, one being that the major focus of these campaigns is on individuals rather than systemic change – it’s cheaper to offer diversity training than try to change institutions. There are countless scientists who, despite evidence to the contrary, think improving diversity might contravene their meritocracy. And the leaky-pipeline model perpetuates an idea that we have to “fix” women rather than the system.
In the mid-1990s tenured women faculty at MIT’s School of Science collected information about their professional lives. They found that women were marginalized throughout their academic careers; with smaller allocations of space, reduced access to resources, less recognition for their work and exclusion from top-level decision making. The newly formed Committee on Women Faculty made several recommendations to steer MIT towards more gender parity, including appointing more women for influential leadership positions, replacing administrators with a track record of discrimination, ensuring pay equity, reducing stigma around childbearing and family leave, and reforming recruitment practices. A 2011 follow-up report reflected improvement, pointing to increased numbers of women faculty in the School of Science, from 8% in 1994 to 19% by 2010. The report did still highlight problems that remained, such as disproportionate expectations placed on women to take on time-consuming service positions and continued systematic exclusion and devaluing of women faculty by senior men.
Backing brilliance: Jocelyn Bell Burnell (centre) with student supporters of the Bell Burnell Graduate Scholarship Fund, which supports PhD physics researchers from underrepresented groups. (Courtesy: Institute of Physics)
Since the mid-2000s the IOP’s Juno Award and the Equality Challenge Unit’s Athena Swan Charter have recognized departmental commitments to improving the environment for women scientists. As of 2019, similar schemes have been established in Canada (Made-in-Canada), America (Sea Change) and Australia (Science in Australia Gender Equality, SAGE). These awards recognize that diversity doesn’t happen without inclusion – that is, efforts to increase the representation of women, people of colour or LGBTQ+ physicists won’t last unless they are made to feel welcome and able to contribute.
The Royal Society of Chemistry’s 2018 Breaking the Barriers report called for cultural change within academia, and identified three key challenges to women’s progression: short-term funding and out-of-date metrics of success; poor academic culture; and difficulties balancing responsibilities with family life. Improving diversity in academic science can often feel like an impossible task – but there are simple steps we could all take to make it more fair for everyone.
Better careers advice, discussions about stereotypes and whole-school commitments to gender equality can have a marked impact on the proportion of girls who study physics at high school.
Social media has transformed the opportunities for marginalized communities, turning the experiences that isolated women and people of colour often endure in scientific research into a chance to share ideas with a network of like-minded individuals around the world. In the past few years a number of international communities have formed, including 500 Women Scientists, 500 Queer Scientists and Minorities in STEM. These organizations raise awareness around issues affecting underrepresented communities in STEM, while increasing the visibility of scientists from diverse backgrounds and experiences.
Institutions and conference organizers should ensure that they have enforceable codes of conduct in place, which define the behaviour expectations on behaviour of all staff and outline a clear disciplinary process.
From refusing to sit on manels (all-male panels) to supporting women on social media, men have a considerable role to play in challenging inequity in science.
Appointing mentors to students and early-career researchers from underrepresented groups can transform their experiences, improving their confidence and likelihood to stay in science.
Universities that have better access to shared parental leave and childcare have more women professors on their staff.
A more equitable institutional merit system must factor outreach, mentorship and service efforts into considerations of tenure, institutional awards and promotions.
On reporting results on the pervasiveness of gender harassment in physics departments, Lauren Aycock, a AAAS Science and Technology Policy Fellow at the Department of Energy, said “A lot of times, people study how women can change to better fit in a field or be more successful…perhaps physics needs to think about changing itself.”
Note: this article has been updated since publication in the August 2019 issue of Physics World.
Jess Wade (click link below for full bio) has been recognized in the Queen’s Birthday Honours 2019 for services to gender diversity in science, @jesswade. Maryam Zaringhalam is a Science and Technology Policy Fellow of the American Association for the Advancement of Science based in Washington DC, US. She is a senior producer for the podcast and show The Story Collider and serves on the leadership team for 500 Women Scientists, @webmz_
Researchers have made high-performance thick organic light-emitting diodes (OLEDs) by combining organic thin films and organic-inorganic perovskite transport layers. The materials, which have the same light-emitting efficiencies as reference thin OLEDs, could be used to make affordable displays and screens that emit the same colour from all viewing angles.
OLEDs make use of layers of organic molecules to efficiently convert electricity into light. The organic layers are placed between two electrodes, one of which is usually transparent. They are ideal for applications in next-generation displays and lighting but the problem is that they need to be made as thin as around 100 nm. This is because organic molecules, while being excellent emitters of light, are generally poor conductors. Only such thin layers can carry electricity to the central, active light-emitting part of a device.
The drawback of thin layers is that they cannot completely cover defects and residues on a substrate. These defects produce shunting paths between the electrodes. Shunting paths are a nuisance since it is through these that charge carriers bypass the organic layers without recombining to produce light. This leads to low efficiency or even complete device failure in the case of electrical shorts. What is more, light that is reflected between the front and back of the thin layers produces cavity effects that can distort the emission colour at large viewing angles.
Making thicker films
Thicker organic transport layers are a possible solution to this problem, but the thicker the layer, the higher the driving voltage needs to be.
Although researchers have tried to make thick OLEDs using organic single crystals, these cannot be mass produced. They have also tried chemically doping the organic layers to increase their electrical conductivity, but additional light absorption bands that reduce electroluminescence efficiency appear in the materials.
A team from Kyushu University in Japan says that it may now have found an answer to this challenge – by using the organic-inorganic perovskite methylammonium lead chloride, CH3NH3PbCl3 (MAPbCl3), instead of organic molecules as the transport layer. In their devices, the researchers sandwiched a layer of light-emitting molecules typically employed in OLEDs between the perovskite layers. They were thus able to increase the total thickness of the active MAPbCl3 layers to 2000 nm, which is more than 10 times the thickness of standard OLEDs, without the need for high driving voltages.
The films also have a low surface roughness, which means that they can better cover a substrate and supress the formation of the dreaded shunting paths. They do not absorb light in the visible region either, which is why they can be used to make thicker OLEDs without affecting the internal electroluminescence quantum efficiency.
Thanks to X-ray diffraction patterns and absorption spectra of the films, the researchers also confirmed that the films are stable in air even after 11 days. Another non-negligible advantage, they say, is that OLEDs made using these films could be cheaper because they cost less than organic materials do.
Overturning 30 years of thinking
Until now, researchers have mainly employed perovskites, which have an ABX3 structure, where A is caesium and methylammonium (MA) or formamidinium (FA), B is lead or tin and X is chlorine, bromine or iodine, as light emitters. This is because they can absorb light over a broad range of solar spectrum wavelengths thanks to their tunable bandgaps. In this work, however, the Japan team has used them for just transporting electricity – they are good in this respect too since charge carriers can diffuse through them quickly and over long lengths – and kept the organic molecules for the light emission part. In this way, it was able to produce thick devices that have the same light emitting efficiencies as reference thin OLEDs.
“These results overturn 30 years of thinking that OLEDs are limited to thin films and open new paths for low-cost, reliable and uniform fabrication of OLED-based displays and lighting,” says team leader Chihaya Adachi. “Based on this work, perovskites will be seen in a new light as versatile, high-performance materials for supporting roles in not only OLEDs but also other organic electronic devices, such as lasers, memory devices, and sensors.”
Collagen is the main component of most tissues and organs in the body but it has proved difficult to produce in the laboratory using 3D printing. A team of researchers at Carnegie Mellon University in Pittsburgh in the US has now developed a new technique that makes use of a support gel to 3D print heart tissue containing collagen. The method, dubbed FRESH (for freeform reversible embedding of suspended hydrogels) can produce parts of the heart at various scales, from capillaries to the full organ. This structure even contracts when made using human cardiac muscle cells.
Although 3D printing (also known as additive manufacturing) has been around since the 1980s, it is only in the last two decades that researchers have used it to fabricate biological cells and structures for applications in regenerative medicine. The technique has recently come along in leaps and bounds with the fabrication of patterned tissues, vascular-like networks that can be perfused with living cells and nutrients, and implantable scaffolds. However, printing living cells and soft biomaterials such as extracellular matrix (ECM) proteins, like collagen, has been difficult.
“Soft and squishy”
“This is because cells and tissue are soft and squishy, which means it is nearly impossible to 3D print them without having them collapse,” explains study leader Adam Feinberg. “Indeed, 3D bioprinting up to now has generally been limited to very thin and tiny scaffolds. In our work we have solved this problem by 3D bioprinting inside a ‘support’ gel that prevents the cells and hydrogels (similar to gelatine) from collapsing.”
With their technique, the researchers say that they are able, for the first time, to 3D print collagen, which is the major structural protein in the body, with the same ease that we can 3D print plastic, metals and other materials. “Being able to do this means that we can now print scaffolds and tissues that actually have biological function,” says Feinberg.
New improved FRESH
The team first put forward its FRESH technique in 2015 and has now developed a new and improved version that makes use of rapid changes in pH to self-assemble collagen and force it to solidify. The method works by extruding bioinks containing unmodified collagen from a needle in the 3D printer, which contains a special support bath composed of a gelatine microparticle slurry that provides support during printing. The needle extrudes thin layers of collagen and cells and these layers then stack on top of each other to create the 3D object. Once the printing is complete, the researchers raise the temperature from room temperature to body temperature (37°C), which gently melts the support and releases the printed scaffold.
The technique can produce complex structures with functional architectures that can be further embedded with living cells or complex vascular-like networks at printing resolutions of up to 20 microns, say the researchers. Cardiac ventricles printed using human cardiac muscle cells are able to contract synchronously and propagate action potentials in a particular direction – just like a real heart. The heart wall also thickens by up to 14% during the phase of the heartbeat known as peak systole – again similar to the real organ.
Patient-specific anatomical structures
The researchers say they can also create patient-specific anatomical structures: “Here, we start with a magnetic resonance imaging (MRI) or micro-computed tomography (CT) image of a patient’s entire heart or just a component, such as a heart valve,” explains Feinberg. “This allows us to create a 3D computer model matched to the patient. Next, we use the computer to convert the 3D model of the heart valve, for example, into instructions that tell the 3D printer what to do.”
There are currently no other methods to 3D bioprint collagen with the resolution and fidelity that we can achieve with FRESH, he tells Physics World. “Importantly, the technique can also use unmodified collagen, meaning we can print pure collagen and use changes in pH to transform the liquid collagen into a gel. Other methods that have been able to print collagen typically needed to chemically modify the collagen or mix it with other materials to improve printability.”
Broad applications in tissue engineering and regenerative medicine
In their work, which they report in Science 10.1126/science.aay0478, the researchers focused on building the heart and its components. “What is really exciting, however, is that collagen – being the major protein in nearly every tissue and organ in the body – has broad applications in tissue engineering and regenerative medicine,” explains Feinberg. “We have also developed custom bioprinters for FRESH and released the designs as open source hardware that we hope the research community will widely adopt. This will hopefully lead to new research and ultimately treatments for a range of diseases in the years to come.”
The team says that it is now busy continuing to build more complex cellularized models of the heart – initially to understand how heart muscle forms and functions, but also with a view to replacing damaged regions of the heart in the long term. “We are also working on other parts of the body, including building collagen scaffolds to repair damaged skeletal muscle, regenerating the trachea and other tissues, and creating more realistic models of mammary ducts to study and improve treatments for breast cancer.”
And maintaining warming below the more ambitious target of 1.5 °C will require an even bigger investment boost – nearly 80% for Europe and nearly 150% for China, say researchers in Austria.
The team modelled the dependency of low-carbon energy capacity on investment. Their results suggest that meeting the goals outlined in the Paris Agreement will require strong policy incentives.
“A radical shift of investments away from fossil fuels and towards renewables and energy efficiency is needed,” says Wenji Zhou of the International Institute for Applied Systems Analysis. “China and Europe are actually doing well, given the fact that the current low-carbon shares of their total energy investments are significantly higher than the world’s average. Nevertheless, the investment gaps are still considerable.”
China and Europe are expected to lead the way in low-carbon investments, now that the US has stepped back from implementing the Paris Agreement. While there have been broad estimates of the necessary increases in low-carbon energy investment worldwide, a detailed comparison of the cases for China and Europe was absent.
“We wanted to better understand the possible pathways that China and Europe might take to decarbonize their respective energy systems in light of their ambitious targets for reducing greenhouse gas emissions, and then from that back out what investment flows would likely be needed to realize these futures,” says Zhou.
Zhou and colleagues first mapped out several future scenarios for their model, including a business-as-usual scenario based on 2015 policies, a goal to limit temperatures well below 2 °C and a goal to limit temperatures close to 1.5 °C. Using the MESSAGEix-GLOBIOM model, they then honed in on China and Europe and analysed energy investment pathways that were compatible with the scenarios.
Relative to the business-as-usual scenario, Europe and China had to increase investments by 38% and 65%, respectively, for the 2 °C scenario, and by 79% and 149% for the 1.5 °C scenario.
Zhou believes these figures should not come as a surprise, and that decarbonization is “the inexorable trend”. The researcher adds: “this is extremely important for the owners of fossil fuel assets. I think … our study could serve as a starting point for them to reconsider their investment strategies, and to take actions as soon as possible to hedge against the investment risk in the upcoming low-carbon future.”
But Zhou notes that incentives will still be needed, including corporate initiatives such as the Task Force on Climate-related Financial Disclosures, the Science-Based Targets Initiative and the Oil and Gas Climate Initiative, all of which aim to address climate concerns collaboratively. “We think these initiatives provide great examples for multilateral corporations at different levels,” he says.
