The team published the findings Oct. 20 in the journal Science Advances. The researchers found that a harsh workplace climate, which can include harassment and feelings of not belonging, was the most common reason women left academia. This attrition affects not only early-career professionals, but also those who have achieved the highest ranks in universities, the study found.

This finding helps to explain, in part, why women remain underrepresented among faculty in nearly all academic fields in the U.S., said Katie Spoon, the paper’s first author and a PhD student in the Department of Computer Science. For example, only 28% of professors in science, technology, engineering and math (STEM) fields are women in the U.S., despite women receiving 40% of STEM PhDs for the past 10 to 15 years.

“If you look back at the literature from 20 or 30 years ago, it painted a much bleaker picture than many of the newer studies today,” said Aaron Clauset, the paper’s corresponding author and a professor of computer science. “Things are changing, but there is still a lot of work left to do.”

Previous research on gendered attrition in academia tended to have a limited scope.

Many studies investigated faculty retention only among assistant professors, in STEM fields, or at high-prestige institutions, due to the difficulties in finding and reaching faculty who left academia.

Spoon and her team analyzed a census of employment records of all 245,270 tenure-track and tenured professors from 391 PhD-granting universities and institutions in the U.S. They came from STEM fields, but also disciplines like social sciences and business. The tenure track is a professor’s pathway to promotion. Faculty members usually start as assistant professors without tenure. If they get promoted, they become tenured associate professors, and eventually they can be promoted to full professors, an indefinite appointment that tends to come with more academic freedom and job security.

The researchers found women are leaving academia at a higher rate than men at every career stage, especially after they receive full professorship. During their appointment as assistant professors, women are 6% more likely to leave their jobs than men each year. The attrition rate is higher among full professors, where women professors are 19% more likely to leave academia than men each year.

“We were surprised to see the gender gap actually grow after faculty received tenure, given how important the title is,” Spoon said. “This result suggests that perhaps the field has neglected thinking about tenured women and their experiences.”

The team also surveyed more than 10,000 current and former faculty members for factors that led or could lead to their decision to leave a faculty job. The result showed women are more likely to feel pushed by a variety of factors out of their faculty positions, while men are more likely to be pulled toward more attractive jobs elsewhere. The most common reasons women, especially tenured women, reported for leaving academia were harsh workplace climates, which can include dysfunctional leadership, harassment, discrimination and feelings of not belonging.

While previous research has suggested that women are more likely to leave academia in pursuit of better work-life balance, the new paper found that male faculty were about as likely to leave for this reason.

“We see an emphasis on work-life balance among early career faculty members,” said Clauset. “But the issue with workplace climate is the dominating factor among the women tenured professors, a position that lasts the majority of one’s academic career.”

The researchers hope their paper will inspire administrators nationwide to take action.

“It can start with asking faculty, particularly women, what needs to be done, listening, and taking specific, concrete steps to address their concerns,” Spoon said.

The fossils were found 40 years ago in north-eastern France. An international team of palaeontologists from the Naturkunde-Museum Bielefeld in Germany, the Institute of Paleobiology of the Polish Academy of Sciences in Warsaw, Poland, the Natural History Museum in Luxembourg and The Museum of Evolution at Uppsala University in Sweden have now analysed them and identified them as a new pliosaur genus: Lorrainosaurus.

Pliosaurs were a type of plesiosaur with short necks and massive skulls. They appeared over 200 million years ago, but remained minor components of marine ecosystems until suddenly developing into enormous apex predators. The new study shows that this adaptive shift followed feeding niche differentiation and the global decline of other predatory marine reptiles over 170 million years ago.

Lorrainosaurus is the oldest large-bodied pliosaur represented by an associated skeleton. It had jaws over 1.3 m long with large conical teeth and a bulky ‘torpedo-shaped’ body propelled by four flipper-like limbs.

“Lorrainosaurus was one of the first truly huge pliosaurs. It gave rise to a dynasty of marine reptile mega-predators that ruled the oceans for around 80 million years,” explains Sven Sachs, a researcher at the Naturkunde-Museum Bielefeld, who led the study.

This giant reptile probably reached over 6 m from snout to tail, and lived during the early Middle Jurassic period. Intriguingly, very little is known about plesiosaurs from that time.

“Our identification of Lorrainosaurus as one of the earliest mega-predatory pliosaurs demonstrates that these creatures emerged immediately after a landmark restructuring of marine predator ecosystems across the Early-to-Middle Jurassic boundary, some 175 to 171 million years ago. This event profoundly affected many marine reptile groups and brought mega-predatory pliosaurids to dominance over ‘fish-like’ ichthyosaurs, ancient marine crocodile relatives, and other large-bodied predatory plesiosaurs,” adds Daniel Madzia from the Institute of Paleobiology of the Polish Academy of Sciences, who co-led the study.

Pliosaurs were some of the most successful marine predators of their time.

“Famous examples, such as Pliosaurus and Kronosaurus — some of the world’s largest pliosaurs — were absolutely enormous with body-lengths exceeding 10 m. They were ecological equivalents of today’s Killer whales and would have eaten a range of prey including squid-like cephalopods, large fish and other marine reptiles. These have all been found as preserved gut contents,” said senior co-author Benjamin Kear, Curator of Vertebrate Palaeontology and Researcher in Palaeontology at The Museum of Evolution, Uppsala University.

The recovered bones and teeth of Lorrainosaurus represent remnants of what was once a complete skeleton that decomposed and was dispersed across the ancient sea floor by currents and scavengers.

“The remains were unearthed in 1983 from a road cutting near Metz in Lorraine, north-eastern France. Palaeontology enthusiasts from the Association minéralogique et paléontologique d’Hayange et des environs recognised the significance of their discovery and donated the fossils to the Natural History Museum in Luxembourg,” said co-author Ben Thuy, Curator at the Natural History Museum in Luxembourg.

Other than a brief report published in 1994, the fossils of Lorrainosaurus remained obscure until this new study re-evaluated the finds. Lorrainosaurus indicates that the reign of gigantic mega-predatory pliosaurs must have commenced earlier than previously thought, and was locally responsive to major ecological changes affecting marine environments covering what is now western Europe during the early Middle Jurassic.

“Lorrainosaurus is thus a critical addition to our knowledge of ancient marine reptiles from a time in the Age of Dinosaurs that has as yet been incompletely understood,” says Benjamin Kear.

“The ability to make aligned muscle in a lab setting means that we can develop model tissues for understanding muscle in healthy and diseased states and for developing and testing new therapies that combat muscle injury or disease,” says senior author Ritu Raman, an MIT engineer. A better understanding of the rules that govern muscle growth could also have applications in robotics, she adds.

In a previous investigation, Raman and colleagues found that “exercising” muscle fibers by making them contract in response to electrical stimulation for 30 minutes a day over the course of 10 days made the fibers stronger. This time, the researchers wanted to explore whether mechanically stimulating the muscle fibers over the same time frame (rather than letting them respond on their own) would have the same result. To investigate, they developed a method to mechanically stimulate muscle tissue that differs from typical lab techniques.

“Generally, when people want to mechanically stimulate tissues in a lab environment, they grasp the tissue at both ends and move it back and forth, stretching and compressing the whole tissue,” said Raman. “But this doesn’t really mimic how cells talk to each other in our bodies. We wanted to spatially control the forces between cells within a tissue, matching native systems.”

To stimulate the muscle cells in a more true-to-life way, Raman and her team grew cells in a Petri dish on a soft gel that contained magnetic particles. When they would move a magnet back and forth under the gel, the particles moved back and forth, too, which “flexed” the cells. The researchers could precisely control the way the gel moved, and, in turn, the magnitude and direction of the forces the cells within experienced, by changing the strength and orientation of the magnet. To measure the alignment of the muscle fibers within the tissues and whether they contracted in synchrony, the team’s collaborators at Boston University developed a custom software that automatically tracked videos of the muscle and generated graphs of its movement.

“We were very surprised by the findings of our study,” said Raman. While mechanically stimulating the muscle fibers over the 10-day period did not seem to make them any stronger, it did cause them all to grow in the same direction.

“Furthermore, we were excited to find that, when we triggered muscle contraction, aligned muscle was beating synchronously, whereas non-aligned muscle was not beating rhythmically,” said Raman. “This confirmed our understanding that the form and function of muscle are intrinsically connected, and that controlling form can help us control function.”

Raman and colleagues plan to take the study further by investigating how different mechanical stimulation regimens impact both healthy and diseased muscle fibers. Additionally, they plan to study how mechanical stimulation affects other types of cells.

“Our work clearly showed that cord formation is important for infection and why this highly ordered architecture might be important for pathogenesis,” says senior author Vivek Thacker, who led the work at the Global Health Institute at École Polytechnique Fédérale de Lausannen (EPFL) in Switzerland and is now based at the Department of Infectious Diseases at Heidelberg University in Germany.

The study used a unique combination of technologies to address the role of MTB cord formation. One was a lung-on-chip model, which allowed the researchers to get a direct look at “first contact” between MTB and host cells at the air-liquid interface in the lungs. This revealed that cord formation is prominent in early infection. The researchers also used a mouse model that develops pathologies mimicking human tuberculosis, allowing them to obtain tissue that could be studied using confocal imaging and confirming that cording also occurs early in infection in vivo.

The work yielded several new findings about how these cords interact with and compress the cell nucleus, how this compression affects the immune system and connections between host cells and epithelial cells, and how cord formation affects the alveoli in the lungs. The study also revealed how these cords retain their structural integrity and how they increase tolerance to antibiotic therapy.

“There is an increasing understanding that these mechanical forces influence cellular behavior and responses, but this aspect has been overlooked since traditional cell culture models do not recapitulate the mechanical environment of a tissue,” says Melanie Hannebelle, formerly at EPFL’s Global Health Institute and now at Stanford University. “Understanding how forces at the cellular and tissue level or crowding at the molecular level affects cell and tissue function is therefore important to develop a complete picture of how biosystems work.”

“By thinking of MTB in infection as aggregates and not single bacteria, we can imagine new interactions with host proteins for known effectors of MTB pathogenesis and a new paradigm in pathogenesis where forces from bacterial architectures affect host function,” says Thacker.

Future research will focus on understanding whether cord formation enables new functionality to known effectors of MTB pathogenesis, many of which are located on the MTB cell wall. In addition, it will look at the consequence of tight-packing on the bacteria within the clump and how this may lead to a protective effect against antibiotics.

“Antibiotic therapy is the mainstay of treatment for tuberculosis infections, but therapeutic regimens are long and complicated, with an increasing threat of drug resistance,” says Richa Mishra, the other first author who is currently at EPFL’s Global Health Institute. “There is a recognized need for host-directed therapies or therapies that inhibit specific virulence mechanisms that can shorten and improve antibiotic therapy.”

The discovery of the burst, named FRB 20220610A, was made in June last year by the ASKAP radio telescope in Australia [1] and it smashed the team’s previous distance record by 50 percent.

“Using ASKAP’s array of dishes, we were able to determine precisely where the burst came from,” says Stuart Ryder, an astronomer from Macquarie University in Australia and the co-lead author of the study published today in Science. “Then we used [ESO’s VLT] in Chile to search for the source galaxy, [2] finding it to be older and further away than any other FRB source found to date and likely within a small group of merging galaxies.”

The discovery confirms that FRBs can be used to measure the ‘missing’ matter between galaxies, providing a new way to ‘weigh’ the Universe.

Current methods of estimating the mass of the Universe are giving conflicting answers and challenging the standard model of cosmology. “If we count up the amount of normal matter in the Universe — the atoms that we are all made of — we find that more than half of what should be there today is missing,” says Ryan Shannon, a professor at the Swinburne University of Technology in Australia, who also co-led the study. “We think that the missing matter is hiding in the space between galaxies, but it may just be so hot and diffuse that it’s impossible to see using normal techniques.”

“Fast radio bursts sense this ionised material. Even in space that is nearly perfectly empty they can ‘see’ all the electrons, and that allows us to measure how much stuff is between the galaxies,” Shannon says.

Finding distant FRBs is key to accurately measuring the Universe’s missing matter, as shown by the late Australian astronomer Jean-Pierre (‘J-P’) Macquart in 2020. “J-P showed that the further away a fast radio burst is, the more diffuse gas it reveals between the galaxies. This is now known as the Macquart relation. Some recent fast radio bursts appeared to break this relationship. Our measurements confirm the Macquart relation holds out to beyond half the known Universe,” says Ryder.

“While we still don’t know what causes these massive bursts of energy, the paper confirms that fast radio bursts are common events in the cosmos and that we will be able to use them to detect matter between galaxies, and better understand the structure of the Universe,” says Shannon.

The result represents the limit of what is achievable with telescopes today, although astronomers will soon have the tools to detect even older and more distant bursts, pin down their source galaxies and measure the Universe’s missing matter. The international Square Kilometre Array Observatory is currently building two radio telescopes in South Africa and Australia that will be capable of finding thousands of FRBs, including very distant ones that cannot be detected with current facilities. ESO’s Extremely Large Telescope, a 39-metre telescope under construction in the Chilean Atacama Desert, will be one of the few telescopes able to study the source galaxies of bursts even further away than FRB 20220610A.

Notes

[1] The ASKAP telescope is owned and operated by CSIRO, Australia’s national science agency, on Wajarri Yamaji Country in Western Australia.

[2] The team used data obtained with the FOcal Reducer and low dispersion Spectrograph 2 (FORS2), the X-shooter and the High Acuity Wide-field K-band Imager (HAWK-I) instruments on ESO’s VLT. Data from the Keck Observatory in Hawai’i, US, was also used in the study.