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Physics explains why humans can walk through crowded places and not spill their coffee

The Nobel Prize for Physics is almost upon us, but before we know who is heading to Stockholm (maybe via Zoom again), the Ig Nobel prizes take the limelight. Meant to make you “first laugh, then think”, the Ig Nobels were held online yesterday for the second time in a row given the ongoing COVID-19 pandemic.

This year’s physics prize went to Alessandro Corbetta from Eindhoven University of Technology and colleagues for explaining why pedestrians don’t constantly collide with one another when walking. The researchers spent six months taking “high-resolution” data of people moving in a busy train station in Eindhoven and modelled their constantly evolving trajectories using statistical physics.

In a similar vein, the “kinetics” Ig Nobel prize examined the role that distraction plays when people are on the move. The researchers from Japan, Switzerland and Italy were rewarded for work that showed why sometimes people do collide with one another and why avoidance manoeuvres are normally a cooperative process. At least it goes some way to showing why people glued to their phones when walking are more likely to be on a collision course. The other Ig Nobel awardees from yesterday can be found here.

Sloshing coffee

I think it’s safe to say that many physicists love a good cup of coffee. Indeed, if you go to a physics department it’s not uncommon to see trails of coffee drops leading from the coffee lounge back to offices, classrooms and labs (hygiene rules permitting). But it has been left to engineers at Arizona State University to work out the physics of why we usually don’t spill our coffee when we walk.

Ying-Cheng Lai, Brent Wallace and colleagues have studied the coffee-sloshing process using a mathematical cart–pendulum model, which describes the system as mass that hangs on a string beneath a moving cart.

Previously, researchers at Northeastern University had studied how people prevent a ball in a round-bottomed cup from sloshing around. They found that people applied either a low-frequency or high-frequency oscillation to the cup to dampen the motion of the ball.

The curious thing is that for the low-frequency strategy, the oscillations were applied in phase with the motion of the ball, whereas they were applied in antiphase in the high-frequency technique. Now, the Arizona team has used their cart–pendulum model to gain further insights into this transition.

They found that for weak oscillations, there was a sharp switch between in phase and antiphase control at the system’s resonant frequency – something that they said can be fully understood using linear systems control theory. For stronger oscillations, the duo discovered a transition region, rich in behaviour, where the motions of the cart and pendulum are not synchronized.

You might be wondering why the researchers are interested in how humans stop coffee from sloshing around. Although we are extremely good at achieving exquisite control over a complex system like coffee in a cup, humans have very little understanding of how we actually do it. Knowing how could provide important information for creating better prosthetics and robots that are able to perform delicate tasks.

Can a commercial EPID dosimetry system detect radiotherapy treatment errors?

Want to learn more on this subject?

Watch now

Electronic portal imaging dosimetry offers one of the best methods to capture radiotherapy treatment errors on a day-to-day basis, because it is non-interventional, readily available and delivers no extra dose to the patient. But how sensitive is it to the variety of errors that can arise?

In this webinar we detail the methods used to test the sensitivity of PerFRACTION (part of the SunCHECK Platform from Sun Nuclear Corporation) to radiotherapy errors originating from three possible sources:

  • Changes in the radiation beam or EPID position;
  • Changes in the patient position; and
  • Changes in the patient anatomy.

Tests are made on anthropomorphic phantoms, for both 3DCRT and VMAT beams.

The speaker, Paul Doolan, has published a paper on this topic in Biomedical Physics & Engineering Express.

Want to learn more on this subject?

Watch now

Dr Paul Doolan is the General Co-ordinator of Medical Physics at the German Oncology Center, Limassol. After working as a Medical Physicist in the National Health Service in the UK, he completed a PhD in Medical Physics at University College London. He spent a year-long sabbatical at Massachusetts General Hospital and Harvard Medical School, gaining clinical experience in Proton Therapy and performing proton physics research. The key paper from his PhD research, published in Physics in Medicine & Biology, was featured on medicalphysicsweb, was one of the journal’s top 10 downloads in 2015, and has more than 60 citations to date. He has also published his work in Medical Physics, has presented at AAPM, PTCOG and ESTRO meetings, and has a h-index of 8. After his research experiences he returned to the clinic at University College London Hospital and became state registered as a Clinical Scientist. He joined the German Oncology Center at the start of its operation in 2017 and assumed responsibility of the Medical Physics Department as the General Co-ordinator in 2020. He is currently acting as the Secretary of the IPEM Working Party on Online Monitoring of Radiotherapy Treatments and is an Editor for the IPEM SCOPE journal.

Robotic insulin delivery via smart ingestible capsules

The year 2021 marks the 100th anniversary of the discovery of insulin. Since then, insulin has become the safest glucose-lowering therapy for diabetes, administered to patients using syringes, pens and pumps.

But among other barriers to achieving glycaemic control physiologically, some patients find it difficult to inject insulin multiple times per day.

Researchers at Scuola Superiore Sant’Anna and clinicians at the University of Pisa are part of a growing movement to develop closed-loop insulin delivery systems that are completely internal to the human body.

Swallowing your insulin

It all started at a summer school – the idea to use a pill-like capsule as a vehicle for insulin cargo, that is.

Doctoral students and their tutors were brainstorming non-invasive intraperitoneal approaches to restore blood glucose to normal levels in type 1 diabetes patients. They ultimately decided to access the body’s internal organs using smart, drug-loaded ingestible capsules that unload at a device anchored outside the peritoneum, the thin, transparent membrane that lines the walls of the abdominal cavity and encloses the abdominal organs.

Scuola Superiore Sant’Anna professor of bioengineering Arianna Menciassi and the students patented the ensuing robotic device and capsule-based refilling system.

Unlike devices used today, which need external pumps or reservoirs that can introduce complications such as catheter obstructions and pain, the researchers’ implantable robotic device and microinfusion system refills via ingestible magnetic capsules that carry insulin.

Once swallowed, an insulin-filled capsule is carried through the digestive tract by peristalsis until it docks at a pouch containing the device and another small magnet, where a retractable needle punctures the intestinal layer and the peritoneum before poking a hole in the capsule. Once this hole is created, the insulin inside is transferred to the implanted reservoir. The now-empty pill undocks, and the device releases the insulin.

In its current iteration, the implanted device is comparable in size with those available commercially. It’s around 165 g, about the weight of an apple, and is about 1.5 times the size of an Apple AirPods Pro charging case.

Advances in medical robotics

The researchers tested their robot and smart pills in human cadavers and live pigs, monitoring the docking process using fluoroscopy.

“This is the first animal study demonstrating that the intraperitoneal route for physiological hormone delivery is feasible, and that the implanted system for delivery can be refilled by swallowing a simple pill which acts as a refiller shuttle,” says Menciassi.

In theory, the robotic device could be used throughout a person’s life. It recharges wirelessly and is equipped with Bluetooth so that a patient can always remain in contact with the device.

Next on the researchers’ agenda is to optimize the design of the device and solve some engineering challenges, such as improving battery recharge, before conducting more animal trials and pilot tests.

The researchers anticipate it will take three to four years to complete human studies and certify the device before moving to commercialization.

Menciassi hopes this study will “increase the interest and the efforts for in vivo and implantable robotic devices.”

Learn more about the device in Science Robotics.

New theory could help optimize defects in semiconductors

A new universal theory and three basic rules for how defects in semiconductors behave in response to strain could lead to improvements in the electronic properties of a wide range of semiconducting materials. The work, which began with the discovery of a key physical quantity that describes how a semiconductor’s volume changes in the presence of impurities, could help researchers determine the “right” amount of strain to apply, and thus optimize the effects of these impurities.

Defect-induced volume changes

Most materials contain impurities, or dopants, that are either intentionally or unintentionally introduced into the system – for example, during the growth of a crystal. These impurities induce volume changes in their immediate vicinity, thus producing a strain in the material.

In the latest work, researchers led by Bing Huang of Beijing Normal University’s Department of Physics and the Beijing Computational Science Research Center demonstrate that the extent of these volume changes, Δ𝑉, depends on whether the defect is positively- or negatively-charged. More precisely, Huang and colleagues show that volume increases for more negatively-charged defects and decreases for more positively-charged ones; in other words, Δ𝑉 is positive when an electron is added to the defect site and negative when an electron is removed from it.

Three basic rules

To further understand (and therefore predict) the different strain-dependent doping behaviours of semiconductors, Huang and colleagues developed three basic rules to describe how strain affects the properties of semiconductor defects.

The first rule describes how a defect’s formation energy changes in response to strain. In a material under strain, the researchers found that the total energy difference between a neutral semiconductor and a negatively (or positively) charged semiconductor that accommodates extra electrons (or holes) in the material’s valence band will depend on the sign and size of Δ𝑉. This energy difference will either increase or decrease superlinearly as a function of the strain, and the rate at which it does so will be proportional to Δ𝑉. If Δ𝑉 is close to zero, the energy difference will be a parabolic function of strain.

The second rule describes how strain changes the Fermi energy level (a hypothetical energy level that has a 50% probability of containing an electron) when the defect charge state changes. According to this rule, a compressive strain will shift this transition energy level up, while a tensile strain will shift it down.

The third rule describes how strain changes the position of the “pinning” Fermi level. This is an intrinsic effect occurring in semiconductor systems in which the Fermi level is far from the electronic band edge. This effect can significantly limit the doping-induced electron and hole densities, and dramatically degrade the performance of devices like solar cells and transistors. Huang and colleagues’ third rule describes how compressive strain will shift the absolute pinning Fermi level up in energy and a tensile strain will shift it down in energy.

Together, Huang says that these rules could help researchers estimate the “right” strain to apply to a semiconductor to optimize the doping effect of impurities or defects. “We have known for some time that strain can be used to tune doping effects in semiconductors, but a fundamental and general theory to understand the diverse strain-induced changes of different point defects in semiconductors was lacking until now,” he tells Physics World.

Full details of the research are reported in Chinese Physics Letters.

Bose–Einstein condensates hit record low temperature

A new way of controlling the expansion of matter in a freely falling Bose–Einstein condensate (BEC) has produced the coldest effective temperature ever measured: 38 pK (10–12 K) above absolute zero. The method, which allowed researchers in Germany and France to image the condensate’s evolution for more than two seconds, opens the door to enhanced measurements of the gravitational constant g and photon recoil, and could even offer an alternative means of detecting gravitational waves.

BECs are clusters of particles in the same quantum ground state. Since they were first created experimentally in 1995, they have become a testbed for research on the quantum nature of matter. One example is matter–wave interferometry, which is a type of interferometer that uses the wave character of atoms. When this is done with free-falling BECs, the resulting interference pattern will depend partly on gravitational effects, making such experiments sensitive tests of fundamental physical processes.  However, when a BEC is released from the magnetic trap in which it is created, repulsive interactions between its constituent particles quickly get converted into kinetic energy. This causes the BEC to expand until it becomes too dilute to detect via standard absorption imaging, in which a laser beam is sent through the condensate and a camera measures how much light the particles absorbed.

Because the interferometer’s resolution increases with the square of the free-fall time, limiting the condensate’s expansion is crucial. To do this, physicists use magnetic, optical or electrostatic forces to focus the condensate, similar to the way that lenses focus light. These so-called matter–wave lensing methods can cool the BEC’s effective temperature to as low as 50 pK. However, they only affect the temperature along the condensate’s radii, not in the axial direction of its fall. Hence, even with matter–wave lensing, a BEC in free-fall still expands rapidly.

3D matter-wave-lensing

The new method, which is described in Physical Review Letters, addresses this shortcoming by changing the magnetic field used to trap the condensate in a way that causes its shape to oscillate, transforming it from a ball into a thin ellipse. The condensate then enters free-fall when its axial dimension reaches its thinnest point, which keeps its axial expansion rate as low as possible. Magnetic lensing further controls the condensate’s expansion in the radial directions.

To test their technique, researchers led by Ernst Rasel of Leibniz University Hannover used the 110-metre drop tower in Bremen, Germany. The team began by creating a BEC from a cloud of about 100,000 rubidium atoms. These atoms then underwent a 4.74-second free fall, during which absorption images were taken at various points. When the team imaged their free-falling BEC without any matter-wave-lensing techniques, they found that the condensate degraded within 160 ms of release. By applying their technique, they achieved a record-low effective temperature of 38 pK and imaged the BEC for more than 2 seconds. “Our methods enable new experiments or greatly improve existing ones,” says Ernst Rasel, who led the research at IQO.

“A significant step for atom interferometry”

The team say that more complex magnetic lens configurations could reduce some limitations of the current setup, bringing about even tighter control over the BEC’s expansion. Lowering the number of atoms inside the BEC might also lower the expansion rate, reducing the effective temperature to as low as 14 pK. However, it could also reduce the total imaging time as a smaller BEC would more rapidly become too dilute to image.

Florian Schreck, a physicist at the University of Amsterdam in the Netherlands who was not involved in the research, calls the new technique “a significant step for atom interferometry with BECs in situations that allow long free-fall time (e.g. in space or in a drop tower)”. Compared to previous methods, Schreck notes that IQO team’s technique reduces the internal kinetic energy of the gas in all three dimensions, and its simplicity means that it should find wide adoption in rubidium BEC atom interferometry. Translating such a scheme to strontium would, he adds, be “especially interesting”, as strontium is the species of choice for plans to use atom interferometers to detect gravitational waves space.

In the medium term, Rasel and his colleagues plan to demonstrate even longer interferometry times using the Bremen drop tower’s catapult system, after simulations showed that the total imaging time with their technique could be more than 17 seconds. In the future, they also hope to employ their method in the Bose-Einstein Condensate and Cold Atom Laboratory (BECCAL), a planned space-based facility.

Boiling droplets propel themselves across oily films

A mechanism that causes droplets of boiling water to propel themselves rapidly across hot oil films has been identified by Victor Leon and Kripa Varanasi at the Massachusetts Institute of Technology. The duo used high-speed photography to determine the relationship between the fleeting timescales of bubble formation inside the droplet, and their motions over long timescales.

When water droplet is placed on a hot metal surface it will boil and create a cushion of vapour upon which the droplet will “float”. This well-known phenomenon is called the Leidenfrost effect, and the low friction created by the cushion allows droplets to move at speeds of millimetres per second over hot surfaces.

If instead, the surface is coated in a film of hot oil, it may seem intuitive that a droplet placed on top of it would experience far more friction. Yet when doing just that in a new experiment, Leon and Varanasi observed the exact opposite effect: with droplets moving up to 100 times faster than levitating Leidenfrost droplets. To investigate this strange effect, they used high-speed photography  — at 100,000 frames per second — to investigate the mechanisms propelling the droplets.

Trapped bubbles

In their images, the duo identified bubbles of vapour forming at the droplet-oil interface on microsecond timescales, each some distance away from the centre of the droplet. In a Leidenfrost droplet, these bubbles would escape almost immediately – and since they are random, would emerge almost uniformly across the base of the droplet.

In contrast, the oil interface prevents vapour from escaping in this case. As a result, bubbles accumulate inside the droplet, allowing asymmetries to develop over time. Since this vapour is far more insulating than the liquid inside the droplet, it produces thermal disturbances in the oil film. This causes the droplet to vibrate – reducing its friction, while also encouraging additional bubble formation.

Momentum transfer

When the bubbles finally burst through the droplet surface, Leon and Varanasi determined that they transfer momentum to one side of the droplet, propelling it in one direction. Altogether, this process produces a coupling between random, microsecond-scale fluctuations inside a droplet, and its motion over far longer timescales.

When analysing their results using established equations of fluid mechanics, the duo found that their motions were remarkably similar to those of droplets moving across the surfaces of infinitely deep pools of oil – despite the films they used being no more than 100 micron thick. This would greatly reduce the friction experienced by the droplet, allowing it to skim rapidly across the surface.

Through their future research, the duo hopes that the effect could be harnessed to trigger droplet propulsion in controlled directions. If achieved, this could allow for advanced microfluidic devices, which could smartly propel fluids in specific direction. Such devices could include pumps that can operate in microgravity environments; and new breakthroughs in applications such as targeted drug delivery.

The research is described in Physical Review Letters.

Pondering cosmic mysteries with Paul Davies, tandem solar cells could soon be on your roof

Paul Davies has been exploring the esoteric nature of physics in his popular science books since the 1970s. The Arizona State University physicist talks to me about his latest book What’s Eating the Universe and Other Cosmic Questions and also gives some top tips for aspiring science writers.

Tandem solar cells show great promise for boosting the efficiency of solar energy systems. Physics World’s Margaret Harris speaks with Laura Miranda Pérez and Chris Case of UK-based Oxford PV, who explain why combining traditional silicon solar-cell technology with newer perovskite-based devices delivers a significant increase in performance.

  • Margaret Harris has written an extensive blog about tandem solar cells that explains why the combination of silicon and perovskite technologies offers a way of meeting future targets for boosting global photovoltaic generating capacity.
  • Paul Davies will be debating the fluid nature of physical laws at the How the Light Gets In festival in London later this month.

Invading black hole or neutron star caused star to explode, say astronomers

A black hole or a neutron star may have merged with a normal massive star and caused it to explode in a supernova, according to Caltech’s Dillon Dong and colleagues. Dong says that such explosions could occur at minimum rate of “one explosion per 10 million years in a galaxy like the Milky Way”.

Many stars are born in pairs, and two stars massive enough to explode as supernovae can be close companions. In such binary systems, the more massive of the two stars will explode first and in most cases a compact object – a neutron star or a black hole – will be left behind.

Astronomers have speculated that if the compact object is close to its surviving companion star, it can spiral into the star’s atmosphere, eventually sinking to the companion’s core where it disrupts the star, causing it to go supernova prematurely. Now, Dong’s team says that it has discovered evidence for such an event in a search of archive data from the Very Large Array Sky Survey (VSS), covering the period between September 2017 and February 2018.

Anomalous sources

The team looked for anomalous but luminous radio sources. They then compared their candidate sources to equivalent observations of the same part of the sky from the Faint Images of the Radio Sky at Twenty Centimetres (FIRST) survey, which was also conducted by the Very Large Array between 1994 and 2005.

One radio source in particular, catalogued as VT 1210+4956, stood out as not being present in the FIRST data. This means that it appeared sometime between 2005 and 2017. Further investigation found that it is situated in a dwarf galaxy about 500 million light–years away.

Following up with the Low Resolution Imaging Spectrometer on the Keck I telescope on Mauna Kea, Hawaii, Dong’s team identified a massive outflow of ionized gas from the source. The Monitor of All Sky X-ray Image (MAXI) experiment on the International Space Station had also detected a soft X-ray burst from the same location on 14 August 2014.

Compact object

With all these observations to hand, Dong’s team were able to piece together what happened. They suggest that long ago, a massive star in a binary system exploded, leaving behind a compact object. When the other star in the system started nearing the latter stages of its life, it ran out of hydrogen in its core and turned to fusing helium instead. This raised the temperature of the star so hydrogen fusion could occur in the star’s envelope, prompting the star to expand. Gradually, the compact object came to be within the star’s atmosphere.

The gravitational tidal interaction between the compact object and the star’s atmosphere saw the star begin to eject huge amounts of material at a rate of 0.04 solar masses per year. This process is estimated to have begun only about 400 years ago, whereas other stars that experience mass loss before going supernova do so for tens of thousands of years before exploding.

This outflow of material formed a dense torus of circumstellar material around the star, which is what Keck observed. Then, in 2014, the compact object reached the star’s core and started ripping it apart from the inside out. An accretion disc of matter around the compact object formed inside the star, and the compact object’s powerful magnetic fields whipped up some of this matter and blasted it away in relativistic jets that emitted the X-ray burst detected by MAXI, and which prompted the star to explode. When the supernova ejecta slammed into circumstellar material, radio emission was released in the form of synchrotron radiation as charged particles in the debris spiralled around magnetic field lines.

As for the star that exploded, if the compact object that merged with it was a neutron star, then “it’s likely it would’ve accreted enough mass to collapse into a black hole,” Dong tells Physics World. “If it was a black hole, it would’ve just become a more massive black hole.”

Type IIn supernovae

Among those astronomers who predicted the existence of such supernovae is Roger Chevalier, of the University of Virginia. In a 2012 paper, he described what such a merger-induced supernova might look like, suggesting that their existence could explain a type IIn supernovae. This poorly understood class of supernova stays brighter for longer and has narrow hydrogen-emission lines. This suggests that the exploding star is surrounded by material ejected by the star that is blocking much of the hydrogen emission, and which is produces a more sustained afterglow as the supernova shock slams into it.

Although Dong does not mention type IIn supernovae by name, Chevalier thinks that VT 1210+4956 looks like a type IIn with its narrow hydrogen line width.

“I think they make a good case,” Chevalier says. “The radio and X-ray [emission] both indicate a central engine. It’s gratifying to see support for a speculative scenario that aimed to explain why the dense mass loss and supernova occurred at about the same time.”

Now that astronomers know that such supernovae occur, the race is on to find one in the process of exploding. “Much remains unknown because we don’t have early time optical and infrared spectra of the explosion,” says Dong. His next steps will include reassessing the rate at which these supernovae occur. If other, more normal looking supernovae can also be triggered by this mechanism, he speculates that they could be much more common than we realize.

The research is described Science.

Tandem solar cells edge towards 30% efficiency

Late in 2020, scientists in Germany and Lithuania announced a new milestone in so-called “tandem” solar cells – that is, cells made from two different types of photovoltaic material. Writing in Science, the Helmholtz-Zentrum Berlin/Kaunas University team reported that its perovskite/silicon tandem cell had a photovoltaic conversion efficiency (PCE) of 29.15%, beating out the previous maximum of 26.2% for a tandem cell. The researchers also suggested that their device’s record-breaking efficiency was only the beginning, with plenty of room for tandem cells to improve before running up against theoretical and practical limits.

As it turns out, that prediction was accurate – so accurate, in fact, that the efficiency record lasted only a few months. The jump in PCE wasn’t as big this time – the number to beat is now 29.52%, according to a paper published in Applied Physics Letters – but intriguingly, the new record-holder is not a laboratory prototype. Instead, it’s a commercial product, developed by researchers at a UK-based start-up called Oxford PV and scheduled for installation on residential rooftops sometime in 2022, once the company’s factory in Germany is up and running.

At this point, I should declare an interest. For the past few weeks, I’ve been thinking about getting some solar panels myself, and I was intrigued by the prospect of sticking half-a-dozen record-breakers onto my roof. So I e-mailed Chris Case, the chief technology officer (CTO) at Oxford PV and a co-author of the recent paper, to ask if I should wait until his company’s product becomes available.

His answer was quick and to the point. “Get those PV panels installed!” he wrote back. “You don’t have to wait for ours.” Electricity generated from rooftop photovoltaic (PV) panels is, he explained, already cheaper than the UK’s standard grid price, even at the lower efficiencies typical for monocrystalline silicon cells. “You can’t lose and it’s a step towards saving the planet,” he concluded.

Pragmatic approach

Coming from the company’s CTO, that might sound like a less-than-ringing product endorsement. Yet it fits in well with the pragmatic approach that Case and his co-authors outline in their paper. As of 2020, they note, the world produced only 0.7 TW of solar electricity per year – far below the 14 TW required to meet the International Renewable Energy Agency (IRENA)’s 2050 targets. More efficient solar cells will certainly help close that gap, and Case is keen to emphasize that 29.52% is “nowhere near” the maximum PCE for silicon/perovskite tandem cells. However, the time available for installation is short enough, and the required number of panels large enough, that other considerations also play a role.

One such consideration is the mass per solar cell area of each element in a PV panel’s absorber layers. By plotting this “areal mass density” against the element’s average concentration in the Earth’s crust, it becomes possible to estimate the feasibility of manufacturing large quantities of PV panels from that element. For example, the areal mass density of silicon is the highest of any PV material because silicon isn’t very good at absorbing visible light. Silicon-only cells therefore need a relatively thick absorber layer (at least 150 microns) to function well. However, because silicon is extremely abundant, making up some 27.7% of Earth’s crust by mass, its high areal mass density isn’t an issue for solar PV manufacturers.

Perovskites, in contrast, are complex structures with the chemical formula ABX3 (where A is typically caesium, methylammonium or formamidinium; B is lead or tin; and X is iodine, bromine or chlorine). Their limiting element is iodine, which is vastly less abundant than silicon, making up just 0.000049% of the Earth’s crust. However, Case and colleagues note that tandem cells require half as much iodine as their perovskite-only counterparts. This is partly because the total thickness of the perovskite layer is less, but also because the tandem design allows some of the iodine to be replaced with bromine, which is around six times more abundant. All told, the Oxford PV team argue that while “producers of silicon and perovskite-based technologies would be able to source all the required elements well in advance” of IRENA’s 2050 target, “this would not be achievable at current production levels for any of the other technologies”.

So is it worth holding out for slightly-more-efficient solar panels? For me, the answer will probably depend on a bunch of near-term, non-physics-related factors (including semiconductor supply-chain issues stemming from the coronavirus crisis). Over the next few years, though, it seems likely that the advantages of tandem cells will eat into silicon PV’s current 95% market share, thereby bringing greater efficiency – and an exciting new material – to a rooftop near you.

Women more likely to experience author disputes when publishing their research, finds study

Female academics are more likely to have authorship disagreements when publishing their research than their male colleagues. That is according to a global survey of more than 5000 scientists, which also finds that women often feel that they receive less recognition for their work than they deserve.

Almost half of the respondents to the survey – conducted by researchers led by Cassidy Sugimoto, an information scientist at Georgia Institute of Technology – were from the natural sciences and engineering (which included physics). About a third, meanwhile, were biomedical scientists and a fifth came from the social sciences.

The authors of the study found that just over half of respondents (53.2%) have had a disagreement over who to list as authors on a paper as well as the order in which those names appear. Women, however, were 1.38 times more likely than men to have experienced a naming disagreement and 1.25 times more likely to have had a dispute about author order.

Natural sciences and engineering had the lowest proportion of female researchers but the largest difference in disputes, with women 1.5 times as likely as men to report a naming disagreement.

Authorship disputes are often rooted in perceptions of whether contributions have been recognised fairly. Female respondents were more likely to state that they distributed authorship fairly but that their colleagues were unfair in their practices. When asked about which authors – first, last or all – receive the most recognition, women were also more likely to report a gap between who is recognised and who should be.

This, the authors write, suggests dissatisfaction with the current status quo. “Disagreements may be more prevalent for women because they perceive the system as not recognizing those it should,” the authors write. Overall, women felt that they received less credit than they deserved while men were more likely to claim that they received more credit than they deserved.

Author hostility

Limiting further collaboration was the most common outcome of authorship disputes for both men and women. There are, however, differences in behaviour following disagreements. Women are more likely to have observed hostility, while men, according to the findings, are more likely to produce fraudulent research “to compete with or undermine the results of a colleague”. In natural sciences and engineering, men are twice as likely as women to undermine colleagues’ work during meetings or talks as payback for such disputes.

Highlighting the importance of communication, respondents who said they discussed authorship issues during collaborative work had fewer disagreements. But the researchers found that men have a more “authoritarian” style when deciding authorship. Women are more likely to discuss authorship with co-authors at the beginning of the project while men are more likely to do so once a manuscript is ready to submit as well as deciding authorship positions without team consultation.

According to Sugimoto and colleagues, the result show that “implicit” and “idiosyncratic” social norms in science disadvantage those who are not part of the dominant social group. “Opaque authorship has understated gender inequities and consequently created a space where they can increase unchecked,” they write. “Transparency in authorship… is essential for achieving equity in scholarly communication.”

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