“We felt like Sherlock Holmes,” says Mordechai (Moti) Feingold, the Kate Van Nuys Page Professor of the History of Science and the Humanities at Caltech, who explains that he and his former student, Andrej Svoren?ík (MS ’08) of the University of Mannheim in Germany, spent more than a decade tracing copies of the book around the world. Feingold and Svoren?ík are co-authors of a paper about the survey published in the journal Annals of Science.

Moreover, by analyzing ownership marks and notes scribbled in the margins of some of the books, in addition to related letters and other documents, the researchers found evidence that the Principia, once thought to be reserved for only a select group of expert mathematicians, was more widely read and comprehended than previously thought.

“One of the realizations we’ve had,” says Feingold, “is that the transmission of the book and its ideas was far quicker and more open than we assumed, and this will have implications on the future work that we and others will be doing on this subject.”

In the Principia, Newton introduced the laws of motion and universal gravitation, “unifying the terrestrial and celestial worlds under a single law,” says Svoren?ík.

“By the 18th century, Newtonian ideas transcended science itself,” says Feingold. “People in other fields were hoping to find a similar single law to unify their own respective fields. The influence of Newton, just like that of Charles Darwin and Albert Einstein, exerted considerable influence on many other aspects of life, and that is what made him such a canonical figure during the 18th century and beyond.”

Principia Found Behind the Iron Curtain

Svoren?ík says that the project was born out of a paper he wrote for a course in the history of science taught by Feingold. Originally from Slovakia, Svoren?ík had written a term paper about the distribution of the Principia in Central Europe. “I was interested in whether there were copies of the book that could be traced to my home region. The census done in the 1950s did not list any copies from Slovakia, the Czech Republic, Poland, or Hungary. This is understandable as the census was done after the Iron Curtain descended, which made tracing copies very difficult.”

To Svoren?ík’s surprise, he found many more copies than Feingold had expected. The summer after the class, Feingold suggested to Svoren?ík that they turn his project into the first-ever complete, systematic search for copies of the first edition of the Principia. Their ensuing detective work across the globe turned up about 200 previously unidentified copies in 27 countries, including 35 copies in Central Europe. Feingold and Svoren?ík even came across lost or stolen copies of the masterpiece; for example, one copy found with a bookseller in Italy was discovered to have been stolen from a library in Germany half a century earlier.

“We contacted the German library to let them know, but they were too slow to make a decision to buy back the copy or apprehend it somehow, so it ended up back on the market,” says Feingold.

A Rare, Collectible Item

According to the historians, copies of the first edition of the Principia sell today for between $300,000 and $3,000,000 via auction houses like Christie’s and Sotheby’s as well as on the black market. They estimate that some 600, and possibly as many as 750 copies of the book’s first edition were printed in 1687.

The primary person behind the book’s publication was Edmond Halley, a well-known English scientist who made several discoveries about our solar system, including the periodicity of what later became known as Halley’s Comet. Feingold explains that, before the Principia was written, Halley had asked Newton for some calculations regarding elliptical orbits of bodies in our solar system. When Halley saw the calculations, “he got so excited, he rushed back to Cambridge and basically forced Newton to write the Principia,” says Feingold. In fact, Halley funded the publication of the book’s first edition.

Soon after its publication, the book was recognized as a work of genius. “Because Halley had already prepared the public for what was to come,” says Feingold, “there was a widespread recognition that the Principia was a masterpiece.” Later, a “mystique” about Newton started to develop, according to Feingold, exemplified in a story about two students walking in Cambridge and spotting Newton on the street. “‘There goes a man,’ one of them said, ‘who wrote a book that neither he nor anybody else understands,'” says Feingold.

The idea that the Principia was incomprehensible and little read is called into question with the new survey results. Not only does the research show that there was a larger market for the book than once thought, it also demonstrates that people were digesting its contents to a greater extent than realized.

“When you look through the copies themselves, you might find small notes or annotations that give you clues about how it was used,” says Svoren?ík, who has personally inspected about 10 percent of the copies documented in their census. When traveling to conferences in different countries, he would make time to visit local libraries. “You look at the condition of the ownership marks, the binding, deterioration, printing differences, et cetera.” Even without inspecting the books up close, the historians could trace who owned them through library records and other letters and documents, and learn how copies were shared.

“It’s harder to show how much people engaged with a book than simply owned it, but we can look at the notes in the margins and how the book was shared,” says Feingold. “You can assume that for each copy, there are multiple readers. It’s not like today, where you might buy a book and are the only one to read it. And then we can look for an exchange of ideas between the people sharing copies. You start to put together the pieces and solve the puzzle.”

Svoren?ík and Feingold hope that their census, which they call preliminary, will yield information about other existing copies tucked away with private owners, book dealers, and libraries. Continuing this line of research into the future, the historians plan to further refine our understanding of how the Principia shaped 18th-century science.

This form of technology, known as “cold spray,” results in mechanically robust, porous structures that are 40% stronger than similar materials made with conventional manufacturing processes. The structures’ small size and porosity make them particularly well-suited for building biomedical components, like replacement joints.

The team’s paper, “Solid-State Additive Manufacturing of Porous Ti-6Al-4V by Supersonic Impact,” published Nov. 9 in Applied Materials Today.

The paper’s lead author is Atieh Moridi, assistant professor in the Sibley School of Mechanical and Aerospace Engineering.

“We focused on making cellular structures, which have lots of applications in thermal management, energy absorption and biomedicine,” Moridi said. “Instead of using only heat as the input or the driving force for bonding, we are now using plastic deformation to bond these powder particles together.”

Moridi’s research group specializes in creating high-performance metallic materials through additive manufacturing processes. Rather than carving a geometric shape out of a big block of material, additive manufacturing builds the product layer by layer, a bottom-up approach that gives manufacturers greater flexibility in what they create.

However, additive manufacturing is not without its own challenges. Foremost among them: Metallic materials need to be heated at high temperatures that exceed their melting point, which can cause residual stress buildup, distortion and unwanted phase transformations.

To eliminate these issues, Moridi and collaborators developed a method using a nozzle of compressed gas to fire titanium alloy particles at a substrate.

“It’s like painting, but things build up a lot more in 3D,” Moridi said.

The particles were between 45 and 106 microns in diameter (a micron is one-millionth of a meter) and traveled at roughly 600 meters per second, faster than the speed of sound. To put that into perspective, another mainstream additive process, direct energy deposition, delivers powders through a nozzle at a velocity on the order of 10 meters per second, making Moridi’s method sixty times faster.

The particles aren’t just hurled as quickly as possible. The researchers had to carefully calibrate titanium alloy’s ideal speed. Typically in cold spray printing, a particle would accelerate in the sweet spot between its critical velocity — the speed at which it can form a dense solid — and its erosion velocity, when it crumbles too much to bond to anything.

Instead, Moridi’s team used computational fluid dynamics to determine a speed just under the titanium alloy particle’s critical velocity. When launched at this slightly slower rate, the particles created a more porous structure, which is ideal for biomedical applications, such as artificial joints for the knee or hip, and cranial/facial implants.

“If we make implants with these kind of porous structures, and we insert them in the body, the bone can grow inside these pores and make a biological fixation,” Moridi said. “This helps reduce the likelihood of the implant loosening. And this is a big deal. There are lots of revision surgeries that patients have to go through to remove the implant just because it’s loose and it causes a lot of pain.”

While the process is technically termed cold spray, it did involve some heat treatment. Once the particles collided and bonded together, the researchers heated the metal so the components would diffuse into each other and settle like a homogeneous material.

“We only focused on titanium alloys and biomedical applications, but the applicability of this process could be beyond that,” Moridi said. “Essentially, any metallic material that can endure plastic deformation could benefit from this process. And it opens up a lot of opportunities for larger-scale industrial applications, like construction, transportation and energy.”

Co-authors include doctoral student Akane Wakai and researchers from MIT, Polytechnic University of Milan, Worcester Polytechnic Institute, Brunel University London and Helmut Schmidt University.

The research was supported, in part, by the MIT-Italy global seed fund and Polimi International Fellowship.

Research published today in the journal PLosMed investigates the impact of high glucose in mothers with gestational diabetes mellitus (GDM) and changes to infants DNA.

GDM is becoming more frequent around the world alongside a rise in obesity and can increase the risk of complications during pregnancy and childbirth as well as increasing the risk of metabolic disease in the child in later life. High levels of glucose in mothers with GDM have been suggested to trigger epigenetic changes in the developing fetus (chemical modifications to the genetic blueprint of the fetus that function of genes activity) resulting in adverse health outcomes for the child.

Researchers from the University of Southampton and King’s College London studied data from over 550 pregnant women with obesity and their children, from the UK Pregnancies Better Eating and Activity Trial (UPBEAT). The trial aims to improve the diet and physical activity of obese pregnant women across the UK. Compared to women in a control group, who made no changes to their lifestyle during pregnancy, women who were supported in changing their diet to lower glycemic index foods that are broken down less quickly by the body, a reduced fat intake and increasing their physical activity put on less weight and were metabolically healthier.

In this new study, researchers compared the level and pattern of DNA methylation, a major epigenetic mechanism which controls gene activity, in the newborn infants from mothers who developed GDM with those that did not. They then looked at whether a dietary and physical activity intervention during pregnancy altered these modifications in infants born to mothers who developed GDM.

The results showed that GDM and high glucose levels in mothers were linked to changes in the level and pattern of functional modification to the infants DNA. Moreover, they found that the dietary and exercise intervention significantly reduced these methylation changes in the infant associated with GDM in the mothers.

Karen Lillycrop, Professor of Epigenetics at the University of Southampton said, “These findings suggest that improvements to diet and physical activity can have an impact on the development of their children.

“These are very encouraging finding and further studies are now needed to establish whether reducing these epigenetic changes through a healthier lifestyle during pregnancy are accompanied by improved health outcomes for the children in later life.”

Professor Lucilla Poston, Tommy’s Chair of Maternal & Fetal Health and lead investigator of the UPBEAT trial at King’s College London, said: “we have known for some time that children of mothers who had gestational diabetes are a greater risk of obesity and poor control of glucose; this new research implies that epigenetic pathways could be involved.”

Tommy’s chief executive Jane Brewin said: “Obesity during pregnancy can have lifelong negative impacts on mother and baby — so one of the best things mums can do is to improve their health, including their weight, before embarking on a pregnancy. However, this study shows that mums who are overweight and their babies can still benefit from adopting a healthy diet while pregnant. All mums-to-be need access to healthy eating advice, and those who are overweight should be given non-judgemental practical support and encouragement to eat healthily during pregnancy.”

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In an article in Pregnancy Hypertension, a team of researchers at the Medical University of South Carolina (MUSC) found that expression of a set of genes previously studied in the setting of early onset and severe preeclampsia is significantly affected by vitamin D status during late-stage pregnancy.

Exactly how preeclampsia develops is unclear. Recent evidence points to poor development of blood vessels in the placenta — the organ that nourishes the fetus throughout pregnancy. This leads to hypertension and several other complications in the mother. The only cure for preeclampsia is to deliver the fetus, which can be dangerous if done too early.

In a previous study that was supported by pilot funding from the South Carolina Clinical & Translational Research Institute (SCTR), the research team led by Kyu-Ho Lee, M.D., Ph.D., assistant professor in the departments of Pediatrics and Obstetrics and Gynecology at MUSC found that the expression of three genes — NKX2-5, SAM68, and sFLT1 — are highly correlated in the setting of early-onset and severe preeclampsia (EOSPE), with sFLT1 being an identified marker for preeclampsia risk. In the current study, which also received SCTR support, the authors examined the expression of these genes in healthy pregnant women.

“Having observed the correlated expression of these genes in preeclampsia, we wanted to see the pattern of expression of these genes in normal pregnancy,” said Lee. “We had a secondary goal of seeing whether vitamin D status affected the expression of these genes.”

The sFLT1 protein interferes with the activity of vascular endothelial growth factor (VEGF), which is an important regulator of blood vessel development. This reduces vascular growth in the placenta. The amount of sFLT1 in the placenta is regulated in part by SAM68 and NKX2-5, also known as the tinman gene. This hypothesized NKX2-5/SAM68/sFLT1 gene “axis” may contribute to the development of preeclampsia.

“NKX2-5 might be controlling the regulation of sFLT1 and SAM68 in such a way that in preeclampsia, the expression levels of those genes go awry and tilt the vascular development in a direction that might trigger preeclampsia,” said Lee.

Vitamin D affects many aspects of the mother’s health during pregnancy. To investigate how the gene axis is affected by maternal vitamin D status, Lee’s team studied placental samples from 43 pregnant women enrolled in a clinical trial at MUSC organized by their collaborator, MUSC Health neonatologist Carol L. Wagner, M.D., a professor in the Department of Pediatrics. Half of the women received a high dose of vitamin D3 (4,000 IU/day), and the other half received a placebo. The study group included African American, Hispanic American and Caucasian American women.

In contrast to their previous study, the team did not detect significant levels of NKX2-5 in placental tissue samples before a healthy delivery. This finding suggests that NKX2-5 expression is important in early at-risk pregnancies but not healthy pregnancies. However, the team did observe a strong positive correlation between SAM68 and sFLT1 in all study participants.

“The tight correlation between SAM68 and sFLT1 makes us think that there’s a functional relationship between these genes,” said Lee.

Interestingly, when assessed at the last visit before delivery, women who were vitamin D deficient (<100 nmol/L of the vitamin D metabolite 25[OH]D) had significantly higher expression of sFLT1 and lower expression of VEGF in the placenta than women who were vitamin D sufficient.

This study provides novel insight into the activity of the NKX2-5/SAM68/sFLT1 gene axis during healthy pregnancies in a diverse group of women and how it may be affected by the vitamin D status of the mother.

“These results raise the possibility that vitamin D somehow directly regulates sFLT1 and/or SAM68 expression at some level,” said Lee. “However, at this point, we haven’t addressed the exact molecular relationship.”

Future studies might investigate the relationship between vitamin D status and the expression of sFLT1 and SAM68 in mothers diagnosed with preeclampsia.

“Ideally, you would want a study with an equal number of diseased versus control pregnancies that had differential levels of vitamin D,” said Lee. “Then we could look at the incidence of disease in correlation to the levels of vitamin D they achieved and the amount of gene expression that we had observed.”

The team’s current findings contribute to a basic biological understanding of the development of pregnancy and preeclampsia. Lee believes that this understanding will improve the standard of care for treating preeclampsia.

“We can begin to develop clinical markers that would help us gauge the health of a pregnancy during its course,” said Lee. “This could provide warning signs for an increasing risk of pregnancy complication.”

But sometimes bats collide with large walls even though they detect these walls with their sonar system. Researchers from Tel Aviv University (TAU) have concluded that these collisions do not result from a sensory limitation but rather from an error in acoustic perception.

The study was led by Dr. Sasha Danilovich, a former PhD student in the lab of Prof. Yossi Yovel, Head of the Sagol School for Neuroscience and faculty member at the School of Zoology at the George S. Wise Faculty of Life Sciences. Other participants included Dr. Arian Bonman and students Gal Shalev and Aya Goldstein of the Sensory Perception and Cognition Laboratory at the School of Zoology and the Sagol School of Neuroscience. The paper was published on October 26, 2020, in PNAS.

The TAU researchers released dozens of bats in a corridor blocked by objects of different sizes and made of different materials. To their surprise, the researchers discovered that the bats collided with large sponge walls that produce a weak echo as if they did not exist. The bats’ behavior suggested that they did this even though they had detected the wall with their sonar system, indicating that the collision did not result from a sensory limitation, but rather from an acoustic misperception.

The researchers hypothesize that the unnatural combination of a large object and a weak echo disrupts the bats’ sensory perception and causes them to ignore the obstacle, much like people who bump into transparent walls.

The researchers then methodically changed the features of the objects along the corridor, varying their size, texture and echo intensity. They concluded that the bats’ acoustic perception depends on a coherent, typical correlation of the dimensions with objects in nature — that a large object should produce a strong echo and a small object a weak echo.

“By presenting the bats with objects whose acoustic dimensions are not coherent, we were able to mislead them, creating a misconception that caused them to repeatedly try to fly into a wall even though they had identified it with their sonar,” Danilovich explains. “The experiment gives us a peek into how the world is perceived by these creatures, whose senses are so unique and different from ours.”

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