Black Hole ‘Family Portrait’ Is Most Detailed To Date (Astronomy)

An international research collaboration including Northwestern University astronomers has produced the most detailed family portrait of black holes to date, offering new clues as to how black holes form. An intense analysis of the most recent gravitational-wave data available led to the rich portrait as well as multiple tests of Einstein’s theory of general relativity. (The theory passed each test.)

A collection of masses for a wide range of compact objects. The graphic shows black holes (blue), neutron stars (orange) and compact objects of uncertain nature (gray) detected through gravitational waves. Each compact binary merger corresponds to three compact objects: the two coalescing objects and the final merger remnant. Credit: Aaron M. Geller, Northwestern University and Frank Elavsky, LIGO-Virgo.

The team of scientists who make up the LIGO Scientific Collaboration (LSC) and the Virgo Collaboration is now sharing the full details of its discoveries. This includes new gravitational-wave detection candidates which held up to scrutiny—a whopping total of 39, representing a variety of black holes and neutron stars—and new discoveries as a result of combining all the observations. The 39 events averaged more than one per week of observing.

The observations could be a key piece in solving the many mysteries of exactly how binary stars interact. A better understanding of how binary stars evolve has consequences across astronomy, from exoplanets to galaxy formation.

Details are reported in a trio of related papers which will be available in pre-print on Oct. 28 at arxiv.org. The studies also are being submitted to peer-reviewed journals.

The gravitational-wave signals on which the studies are based were detected during the first half of the third observing run, called O3a, of the National Science Foundation’s Laser Interferometry Gravitational-wave Observatory (LIGO), a pair of identical, 4-kilometer-long interferometers in the United States, and Virgo, a 3-kilometer-long detector in Italy. The instruments can detect gravitational-wave signals from many sources, including colliding black holes and colliding neutron stars.

“Gravitational-wave astronomy is revolutionary—revealing to us the hidden lives of black holes and neutron stars,” said Christopher Berry, an LSC member and author of the papers. “In just five years we have gone from not knowing that binary black holes exist to having a catalog of over 40. The third observing run has yielded more discoveries than ever before. Combining them with earlier discoveries paints a beautiful picture of the universe’s rich variety of binaries.”

This illustration shows the merger of two black holes and the gravitational waves that ripple outward as the black holes spiral toward each other. Credit: LIGO/T. Pyle.

Berry is the CIERA Board of Visitors Research Professor in Northwestern’s CIERA (Center for Interdisciplinary Exploration and Research in Astrophysics) and a lecturer at the University of Glasgow. Other Northwestern authors include CIERA members Maya Fishbach and Chase Kimball. CIERA is home to a broad group of researchers in theory, simulation and observation who study black holes, neutron stars, white dwarfs and more.

As a member of the collaboration, Northwestern researchers analyzed data from the gravitational-wave detectors to infer the properties of detected black hole and neutron star binaries and to provide an astrophysical interpretation of these discoveries.

The papers are summarized as follows:

The “catalog paper” details the detections of black holes and neutron stars from the first half of O3a, bringing the total number of detection candidates for that period to 39. This number vastly exceeds detections from the first two observing runs. (The first run had three gravitational-wave detections, and the second had eight.) Previously announced detections from O3a include a mystery object in the mass gap (GW190814) and the first-of-its-kind intermediate mass black hole (GW190521).

In the “populations paper,” the researchers reconstructed the distribution of masses and spins of the black hole population and estimated the merger rate for binary neutron stars. The results will help scientists understand the detailed astrophysical processes which shape how these systems form. This improved understanding of the mass distribution of black holes and knowing that black hole spins can be misaligned suggests there could be multiple ways for binary black holes to form.

Using the set of detections reported in the catalog paper, the researchers conducted detailed analysis by combining everything together. In what they call the “testing general relativity paper,” the authors placed constraints on Einstein’s theory of general relativity. The theory passed with flying colors, and they updated their best measurements on potential modifications.

“So far, LIGO and Virgo’s third observing run has yielded many surprises,” said Fishbach, a NASA Einstein Postdoctoral Fellow and LSC member. “After the second observing run, I thought we’d seen the whole spectrum of binary black holes, but the landscape of black holes is much richer and more varied than I imagined. I’m excited to see what future observations will teach us.”

Fishbach coordinated writing of the populations paper which outlines what the collaboration has learned about the properties of the family of merging black holes and neutron stars.

This illustration generated by a computer model shows multiple black holes found within the heart of a dense globular star cluster. Credit: Aaron M. Geller, Northwestern University/CIERA

Berry helped coordinate analysis as part of a global team to infer the properties of the detections, and he served as an LSC Editorial Board reviewer for the catalog and testing general relativity papers.

Graduate student Chase Kimball, an LSC member, contributed calculations of the rates of mergers to the populations paper. Kimball is co-advised by Berry and Vicky Kalogera, the principal investigator of Northwestern’s LSC group, director of CIERA and the Daniel I. Linzer Distinguished University Professor of Physics and Astronomy in the Weinberg College of Arts and Sciences.

The LIGO and Virgo detectors finished their latest observing run this past March. The data analyzed in these three papers were collected from April 1, 2019, to Oct. 1, 2019. Researchers are in the process of analyzing data from the second half of the observing run, O3b.

The detectors are scheduled to resume observing next year after work is done to increase their detection range.

“Merging black hole and neutron star binaries are a unique laboratory,” Berry said. “We can use them to study both gravity—so far Einstein’s general relativity has passed every test —and the astrophysics of how massive stars live their lives. LIGO and Virgo have transformed our ability to observe these binaries, and, as our detectors improve, the rate of discovery is only going to accelerate.”

References: (1) The “populations” paper is titled “Population properties of compact objects from the second LIGO-Virgo Gravitational-Wave Transient Catalog.” (2) The “catalog” paper is titled “GWTC-2: Compact Binary Coalescences Observed by LIGO and Virgo During the First Half of the Third Observing Run.” (3) The “testing general relativity” paper is titled “Tests of General Relativity with Binary Black Holes from the second LIGO-Virgo.”

Provided by Northwestern University

How The Immune System Deals With The Gut’s Plethora Of Microbes (Biology)

The gut is an unusually noisy place, where hundreds of species of bacteria live alongside whatever microbes happen to have hitched a ride in on your lunch. Scientists have long suspected that the gut’s immune system, in the face of so many stimuli, takes an uncharacteristically blunt approach to population control and protection from foreign invaders–churning out non-specific antibodies with broad mandates to mow the gut’s entire microbial lawn without prejudice.

A large, multi-colored collection of germinal centers observed in the mesenteric lymph node of a mouse. ©Laboratory of Lymphocyte Dynamics of The Rockefeller University.

But now, new research published in Nature suggests that the gut’s local immune system can be quite precise, creating antibodies that appear to home in on specific microbiota.

“It was thought that the gut immune system worked sort of like a general-purpose antibiotic, controlling every bug and pathogen,” says Gabriel D. Victora, an immunologist and head of the Laboratory of Lymphocyte Dynamics . “But our new findings tell us that there might be a bit more specificity to this targeting.”

The research suggests that our immune system may play an active part in shaping the composition of our microbiomes, which are tightly linked to health and disease. “A better understanding of this process could one day lead to major implications for conditions where the microbiome is knocked out of balance,” says Daniel Mucida, head of the Laboratory of Mucosal Immunology.

Specificity in the mouse gut

When faced with a pathogen, the immune system’s B cells enter sites called germinal centers where they “learn” to produce specific antibodies until one B cell emerges, finely-tuned to recognize its target with high efficiency. Dubbed a winner clone, this B cell replicates to generate a mob of cells that produce potent antibodies.

Victora, Mucida, and colleagues set out to study how these B cells interact with the melting pot of bacterial species in the gut–an overabundance of potential targets. Looking at the germinal centers that form in mice intestines, they found that about 1 in 10 of these gut-associated germinal centers had clear winner clones. They then homed in on the winning B cells and found that their antibodies were indeed designed to bind with ever increasing potency to specific species of bacteria living in the gut.

The findings show that even in the gut, where millions of microbes wave their thousands of different antigens and vie for the immune system’s attention, germinal centers manage to select specific, consistent winners.

“We can now investigate the winners and look at evolution in germinal centers as an ecological issue involving many different species, as we try to figure out the rules underlying selection in these complex environments,” Victora says. “This opens up a whole new area of inquiry.”

References: Nowosad, C.R., Mesin, L., Castro, T.B.R. et al. Tunable dynamics of B cell selection in gut germinal centres. Nature (2020). https://doi.org/10.1038/s41586-020-2865-9 link: https://www.nature.com/articles/s41586-020-2865-9

Provided by Rockefeller University

These Spiders Can Hear (Biology)

Ogre-faced spiders, named for their massive eyes, hide during the day and hunt by night, dangling from Florida palm fronds and casting silk nets on insects on the ground and in the air. In addition to their incredible night vision, these spiders also can hear their predators and prey, researchers report in the journal Current Biology on October 29. Having no ears, the spiders use hairs and joint receptors on their legs to pick up sounds from at least 2 meters away. The results suggest that spiders can hear low-frequency sounds from insect prey as well as higher frequency sounds from bird predators.

A frontal view of an ogre-faced spider, showing their large eyes. Credit: Jay Stafstrom.

“I think many spiders can actually hear, but everybody takes it for granted that spiders have a sticky web to catch prey, so they’re only good at detecting close vibrations,” says senior author Ron Hoy, professor of neurobiology and behavior at Cornell University. “Vibration detection works for sensing shaking of the web or ground, but detecting those airborne disturbances at a distance is the province of hearing, which is what we do and what spiders do too, but they do it with specialized receptors, not eardrums.”

Instead of passively waiting for prey to fall into a web and get stuck, ogre-faced spiders use their webs as a weapon. After spending the daylight hours completely still, blending in with the surrounding palmetto fronds, they emerge at night to dangle close to the ground and cast their webs like a net on unwary insects. While they use their keen night vision to catch prey on the ground, they can also catch insects in the air by performing an elaborately choreographed backwards strike, which does not seem to rely on vision.

“In a previous study, I actually put dental silicone over their eyes so they couldn’t see,” says first author Jay Stafstrom, a postdoctoral researcher in the Hoy Lab. “And I found that when I put them back out into nature, they couldn’t catch prey from off the ground, but they could still catch insects from out of the air. So I was pretty sure these spiders were using a different sensory system to hunt flying insects.”

While that study hinted that the spiders might be able to hear, this one showed just how well they can do it. By observing the spiders’ reactions to different tones and measuring their neural response with electrodes placed in the spiders’ brains and legs, the team determined that the spiders could hear sounds of up to 10 kHz in frequency, far higher than the sounds of a walking or flying insect.

“When I played low tone frequencies, even from a distance, they would strike like they were hunting an insect, which they don’t do for higher frequencies,” says Stafstrom. “And the fact that we were able to do that from a distance, knowing we’re not getting up close and causing them to vibrate. That was key to knowing they can really hear.”

Hearing these higher frequencies may not be helpful for hunting, but it may help them stay alert when hiding from their own predators.

The upside-down posture that ogre-faced spiders take when waiting for passing prey. Credit: Jay Stafstrom

“If you give an animal a threatening stimulus, we all know about the fight or flight response. Invertebrates have that too, but the other ‘f’ is ‘freeze.’ That’s what these spiders do,” says Hoy. “They’re in a cryptic posture. Their nervous system is in a sleep state. But as soon as they pick up any kind of salient stimulus, boom, that turns on the neuromuscular system. It’s a selective attention system.”

While these results make it clear that the spiders can detect sounds well, the researchers are next interested in testing their directional hearing—whether they can tell where sounds are coming from. If they can also hear directionally, this might help further explain their acrobatic hunting style.

“What I found really amazing is that to cast their net at flying bugs they have to do a half backflip and spread their web at the same time, so they’re essentially playing centerfield,” says Hoy. “Directional hearing is a big deal in any animal, but I think there are really going to be some interesting surprises from this spider.”

References: Stafstrom et al.: “Ogre-faced, net-casting spiders use auditory cues to detect airborne prey”, Current Biology, 2020. https://www.cell.com/current-biology/fulltext/S0960-9822(20)31418-4

Provided by Cell Press

Hubble Finds ‘Greater Pumpkin’ Galaxy Pair (Astronomy)

Sorry Charlie Brown, NASA’s Hubble Space Telescope is taking a peek at what might best be described as the “Greater Pumpkin,” that looks like a Halloween decoration tucked away in a patch of sky cluttered with stars. What looks like two glowing eyes and a crooked carved smile is a snapshot of the early stages of a collision between two galaxies. The entire view is nearly 109,000 light-years across, approximately the diameter of our Milky Way.

This is a Hubble Space Telescope snapshot of the early stages of a collision between two galaxies that resembles a Halloween carved pumpkin. The “pumpkin’s” glowing “eyes” are the bright, star-filled cores of each galaxy that contain supermassive black holes. An arm of newly forming stars give the imaginary pumpkin a wry smirk. The two galaxies, cataloged as NGC  2292 and NGC  2293, are located about 120 million light-years away in the constellation Canis Major. Credit: NASA, ESA, and W. Keel (University of Alabama)

The overall pumpkin-ish color corresponds to the glow of aging red stars in two galaxies, cataloged as NGC  2292 and NGC  2293, which only have a hint of spiral structure. Yet the smile is bluish due to newborn star clusters, spread out like pearls on a necklace, along a newly forming dusty arm. The glowing eyes are concentrations of stars around a pair of supermassive black holes. The scattering of blue foreground stars makes the “pumpkin” look like it got all glittery for a Halloween party.

What’s going on in this pumpkin-like pair?

If you mix two fried eggs together, you get something resembling scrambled eggs. The same goes for galaxy collisions throughout the universe. They lose their flattened spiral disk and the stars are scrambled into a football-shaped volume of space, forming an elliptical galaxy. But this interacting pair is a very rare example of what may turn out to result in a bigger fried egg—the construction of a giant spiral galaxy. It may depend on the specific trajectory the colliding galaxy pair is following. The encounter scenario must be rare because there’s only a handful of other examples in the universe, say astronomers.

The ghostly arm making the “smile” may be just the beginning of the process of rebuilding a spiral galaxy, say researchers. The arm embraces both galaxies. It most likely formed when interstellar gas was compressed as the two galaxies began to merge. The higher density precipitates new star formation.

The dynamic duo hides out 120 million light-years away in the constellation Canis Major, so it is seen far behind the star-filled foreground plane of our Milky Way galaxy. Therefore, it’s a difficult area to pinpoint far-flung distant background galaxies from the plethora of stars seen in the field.

The galaxy pair was similar to objects tagged by the citizen-science project Galaxy Zoo, where volunteers go hunting for oddball-looking galaxies. Astronomer William Keel, of the University of Alabama in Tuscaloosa, included several of these in the “Gems of the Galaxy Zoos” Hubble program, which is observing several kinds of rare galaxies during short gaps between other scheduled Hubble observations. The Hubble image brought out new details of the close encounter.

Keel speculates that the ultimate destiny for this pair will be to merge into a giant luminous spiral galaxy like UGC 2885, Rubin’s Galaxy, which is over twice the diameter of our Milky Way. Hubble has caught a snapshot of the groundbreaking early stages of a galactic makeover.

Provided by ESA/Hubble Information Centre

Where were Jupiter and Saturn born? (Planetary Science)

New work led by Carnegie’s Matt Clement reveals the likely original locations of Saturn and Jupiter. These findings refine our understanding of the forces that determined our Solar System’s unusual architecture, including the ejection of an additional planet between Saturn and Uranus, ensuring that only small, rocky planets, like Earth, formed inward of Jupiter.

New work led by Carnegie’s Matt Clement reveals the likely original locations of Saturn and Jupiter. © Saturn image is courtesy of NASA/JPL-Caltech/Space Science Institute.

In its youth, our Sun was surrounded by a rotating disk of gas and dust from which the planets were born. The orbits of early formed planets were thought to be initially close-packed and circular, but gravitational interactions between the larger objects perturbed the arrangement and caused the baby giant planets to rapidly reshuffle, creating the configuration we see today.

“We now know that there are thousands of planetary systems in our Milky Way galaxy alone,” Clement said. “But it turns out that the arrangement of planets in our own Solar System is highly unusual, so we are using models to reverse engineer and replicate its formative processes. This is a bit like trying to figure out what happened in a car crash after the fact–how fast were the cars going, in what directions, and so on.”

Clement and his co-authors–Carnegie’s John Chambers, Sean Raymond of the University of Bordeaux, Nathan Kaib of University of Oklahoma, Rogerio Deienno of the Southwest Research Institute, and André Izidoro of Rice University–conducted 6,000 simulations of our Solar System’s evolution, revealing an unexpected detail about Jupiter and Saturn’s original relationship.

Jupiter in its infancy was thought to orbit the Sun three times for every two orbits that Saturn completed. But this arrangement is not able to satisfactorily explain the configuration of the giant planets that we see today. Matt Clement and his co-authors showed that a ratio of two Jupiter orbits to one Saturnian orbit more consistently produced results that look like our familiar planetary architecture. Courtesy of NASA.

Jupiter in its infancy was thought to orbit the Sun three times for every two orbits that Saturn completed. But this arrangement is not able to satisfactorily explain the configuration of the giant planets that we see today. The team’s models showed that a ratio of two Jupiter orbits to one Saturnian orbit more consistently produced results that look like our familiar planetary architecture.

“This indicates that while our Solar System is a bit of an oddball, it wasn’t always the case,” explained Clement, who is presenting the team’s work at the American Astronomical Society’s Division for Planetary Sciences virtual meeting today. “What’s more, now that we’ve established the effectiveness of this model, we can use it to help us look at the formation of the terrestrial planets, including our own, and to perhaps inform our ability to look for similar systems elsewhere that could have the potential to host life.”

The model also showed that the positions of Uranus and Neptune were shaped by the mass of the Kuiper belt–an icy region on the Solar System’s edges composed of dwarf planets and planetoids of which Pluto is the largest member–and by an ice giant planet that was kicked out in the Solar System’s infancy.

References: http://dx.doi.org/10.1016/j.icarus.2020.114122

Provided by Carnegie Institution for Science

Brainstem Neurons Control Both Behaviour And Misbehaviour (Neuroscience)

A recent study at the University of Helsinki reveals how gene control mechanisms define the identity of developing neurons in the brainstem. The researchers also showed that a failure in differentiation of the brainstem neurons leads to behavioural abnormalities, including hyperactivity and attention deficit.

Gene expression determines the differentiation path of embryonic brainstem precursor cells into excitatory (glutamatergic) or inhibitory (GABAergic) neurons. ©Samir Sadik-Ogli.

The mammalian brain is big, but the state of its activity is controlled by a much smaller number of neurons. Many of these are located in the brainstem, an evolutionarily conserved part of the brain, which controls mood, motivation and motor activity. What are the brainstem neurons like? How do they develop in the embryonic brain? How are defects in their development reflected in brain activity and behaviour?

The research group, led by Professor Juha Partanen at the Faculty of Biological and Environmental Sciences, University of Helsinki, has addressed these questions by studying gene regulation in the embryonic brainstem.

The phenotype of a neuron, to a large extent, is determined already early in an embryo. We have shown how certain selector genes, which are expressed soon after the onset of neuronal differentiation, and control the activity of other neuron specific genes, determine the identity of the developing neuron.

The past few years have provided us with very powerful tools to study gene expression in individual cells. By analysing gene products in embryonic brain cells, we can now follow the differentiation paths of neurons and examine what exactly happens when the developing cells take different paths – for example in becoming a neuron either inhibiting or activating its target. Differentiation paths branch to produce the remarkable neuronal diversity that brain function is based on. According to the gene-expression-based identities, the immature neurons find their location in the brain and make contacts with other components of the neural circuitry.

What if the gene expression signposts point in wrong directions and the developing neurons are misrouted? In the brainstem, this has grave consequences on both brain function and behaviour.

In such a situation, “We have studied mice with an imbalance in differentiation of neurons either activating or inhibiting the dopaminergic and serotonergic neurotransmitter systems. These mice are hyperactive and impulsive, they have changes in their reward sensing and learning. Their hyperactivity can be alleviated with drugs used to treat human attention and hyperactivity deficits,” as Partanen clarifies.

In sum, Partanen indicates that, “Despite active research, the developmental basis of many human behavioural disorders are still poorly understood. We do not know yet if the human counterparts of the neurons we studied are involved in these deficits. Nevertheless, from the perspective of behavioural regulation, this specific group of neurons is highly important and there is still lot to learn about them.”

References: Francesca Morello, Daniel Borshagovski, Mantas Survila, Marjo Salminen, Kaia Achim, Juha Partanen, “Molecular Fingerprint and Developmental Regulation of the Tegmental GABAergic and Glutamatergic Neurons Derived from the Anterior Hindbrain”, Cell, 33(2), 108268, 2020. DOI:https://doi.org/10.1016/j.celrep.2020.108268

Provided by University Of Helsinki

Measuring The Expansion Of The Universe: Researchers Focus On Velocity (Astronomy)

Ever since the astronomer Edwin Hubble demonstrated that the further apart two galaxies are, the faster they move away from each other, researchers have measured the expansion rate of the Universe (the Hubble constant) and the history of this expansion. Recently, a new puzzle has emerged, as there seems to be a discrepancy between measurements of this expansion using radiation in the early Universe and using nearby objects. Researchers from the Cosmic Dawn Center, at the Niels Bohr Institute, University of Copenhagen, have now contributed to this debate by focusing on velocity measurements. The result has been published in Astrophysical Journal.

In both observations the redshift is measured from the clarity of the supernova. But in observation 2 (Galaxy 2) the measurement is made on the ejecta from the explosion. The measurements on Galaxy 2 become more uncertain since we don’t know exactly in each case how fast the explosion ejects the material. Never the less it is still made in order to obtain as much data as possible. ©Peter Laursen.

The researchers at the Cosmic Dawn Center found that the measurements of velocity used for determining the expansion rate of the Universe may not be reliable. As stated in the publication, this doesn’t resolve the discrepancies, but rather hints at an additional inconsistency in the composition of the Universe.

Measuring the expansion rate of the Universe

Currently, astronomers measure the expansion of the Universe using two very different techniques. One is based on measuring the relationship between distance and velocity of nearby galaxies, while the other stems from studying the background radiation from the very early universe. Surprisingly, these two approaches currently find different expansion rates. If this discrepancy is real, a new and rather dramatic reinterpretation of the development of the Universe will be the consequence. However, it is also possible that the difference in the Hubble constant could be from incorrect measurements. It is difficult to measure distances in the Universe, so many studies have focused on improving and recalibrating distance measurements. But in spite of this, over the last 4 years the disagreement has not been resolved.

The velocity of the remote galaxies is easy to measure – or so we thought

In the recent scientific article, the researchers from the Cosmic Dawn Center now attempt to shine light on a related problem: the measurement of velocity. Depending on the velocity with which a remote object moves away from us, its light shifts to redder colors. With this so-called redshift it is possible to measure the velocity from a spectrum of a remote galaxy. Unlike measurements of distance, until now it was assumed that velocities were relatively easy to measure.

However, when the researchers recently examined distance and velocity measurements from more than 1000 supernovae (exploding stars) collected during the last 25 years, they found a surprising discrepancy in their results. Albert Sneppen, Masters student at the Niels Bohr Institute explains: “We’ve always believed that measuring velocities was fairly straightforward and precise, but it turns out that we are actually dealing with two types of redshifts”.

The first type, measuring the velocity with which the host-galaxy moves away from us, is considered the most reliable. The other type of redshift measures instead the velocity of matter ejected from the exploding star inside the galaxy. Or, more precisely, the matter from the supernova moving towards us with a few percent of the velocity of light (illustration 1). After compensating for this extra movement the redshift – and velocity – of the host galaxy can be determined. But this compensation requires a precise model for the explosion. The researchers were able to determine that the results from these two different techniques result in two different expansion histories for the Universe, and therefore two different compositions as well.

Are things “broken in an interesting way?”

So, does this mean that the measurements of the early Universe and newer measurements are ultimately a question of imprecise measurements of velocity? Probably not, says Bidisha Sen, one the authors of the article. “Even if we only use the more reliable redshifts, the supernova measurements not only continue to disagree with the Hubble constant measured from the early Universe – they also hint at a more general discrepancy regarding the composition of the Universe”, she says.

Associate professor at the Niels Bohr Institute Charles Steinhardt, is intrigued by these new results. “If we are actually dealing with two disagreements, it means that our current model would be “broken in an interesting way”, he says. “In order to solve two problems, one regarding the composition of the Universe and one regarding the expansion rate of the Universe, rather different physical explanations are required than if we only want to explain a single discrepancy in the expansion rate”.

The Scientific work continues at the Nordic Optical Telescope

With the Nordic Optical Telescope in Gran Canaria the researchers are now acquiring new redshifts from the host galaxies. When they compare these results with the supernova based redshifts, they will be able to see if the two techniques remain different. “We have learned that these sensitive measurements require precise measurements of velocity, and these will be attainable with fresh observations”, Steinhardt explains.

References: Charles L. Steinhardt, Albert Sneppen, and Bidisha Sen, “Effects of Supernova Redshift Uncertainties on the Determination of Cosmological Parameters”, The Astrophysical Journal, Volume 902, Number 1, 2020. https://iopscience.iop.org/article/10.3847/1538-4357/abb140

Provided by University Of Copenhagen

Ancient Marine Predator Had A Built-in Float (Paleontology)

About 240 million years ago, when reptiles ruled the ocean, a small lizard-like predator floated near the bottom of the edges in shallow water, picking off prey with fang-like teeth. A short and flat tail, used for balance, helps identify it as a new species, according to research published in the Journal of Vertebrate Paleontology.

An illustration of Brevicaudosaurus. Credit: Tyler Stone BA ’19, art and cinema; see his website tylerstoneart.wordpress.com

Paleontologists at the Chinese Academy of Scientists and Canadian Museum of Nature have analysed two skeletons from a thin layer of limestone in two quarries in southwest China. They identified the skeletons as nothosaurs, Triassic marine reptiles with a small head, fangs, flipper-like limbs, a long neck, and normally an even longer tail, probably used for propulsion. However, in the new species, the tail is short and flat.

“Our analysis of two well-preserved skeletons reveals a reptile with a broad, pachyostotic body (denser boned) and a very short, flattened tail. A long tail can be used to flick through the water, generating thrust, but the new species we’ve identified was probably better suited to hanging out near the bottom in shallow sea, using its short, flattened tail for balance, like an underwater float, allowing it to preserve energy while searching for prey,” says Dr. Qing-Hua Shang from the Chinese Academy of Sciences, in Beijing.

The scientists have named the new species Brevicaudosaurus jiyangshanensis, from the Latin ‘brevi’ for ‘short,’ ‘caudo’ for ‘tail,’ and the Greek ‘sauros’ for ‘lizard.’ The most complete skeleton of the two was found in Jiyangshan quarry, giving the specimen its species name. It’s just under 60cm long.

Brevicaudosaurus jiyangshanensis, gen. et sp. nov., skeletons in dorsal view. A, IVPP V 18625, holotype; B, IVPP V 26010, referred specimen. Credit: QING-HUA SHANG, XIAO-CHUN WU and CHUN, Journal of Vertebrate Paleontology.

The skeleton gives further clues to its lifestyle. The forelimbs are more strongly developed than the hind limbs, suggesting they played a role in helping the reptile to swim. However, the bones in the front feet are short compared to other species, limiting the power with which it could pull through the water. Most of its bones, including the vertebrae and ribs, are thick and dense, further contributing to the stocky, stout appearance of the reptile, and limiting its ability to swim quickly but increasing stability underwater.

However, thick, high-mass bones act as ballast. What the reptile lost in speed, it gained in stability. Dense bones, known as pachyostosis, may have made it neutrally buoyant in shallow water. Together with the flat tail, this would have helped the predator to float motionless underwater, requiring little energy to stay horizontal. Neutral buoyancy should also have enabled it to walk on the seabed searching for slow-moving prey.

Highly dense ribs may also suggest the reptile had large lungs. As suggested by the lack of firm support of the body weight, nothosaurs were oceanic nut they needed to come to the water surface for oxygen. They have nostrils on the snout through which they breathed. Large lungs would have increased the time the species could spend under water.

Brevicaudosaurus jiyangshanensis, gen. et sp. nov., IVPP V 18625, photographs and outlines of the skull and the mandible in dorsal view. A,B, IVPP V 18625, holotype, in dorsal view; C, D, IVPP V 26010, referred specimen, snout portion of the skull. Zigzag lines indicate broken areas.Abbreviations: art, articular; bo, basioccipital; cqp, cranio-quadrate passage; d, dentary; ec, ectopterygoid; eo, exoccipital; f, frontal; j, jugal; m,maxilla; n, nasal; op, opisthotic; or, orbit; p, parietal; pf, prefrontal; pl, palatine; pm, premaxilla; po, postorbital; pof, postfrontal; pt, pterygoid; q, quadrate;qj, quadratojugal; rap, retroarticular process; sa, surangular; so, supraoccipital; sq, squamosal; st, stapes. Credit: QING-HUA SHANG, XIAO-CHUN WU and CHUN, Journal of Vertebrate Paleontology.

The new species features a bar-shaped bone in the middle ear called the stapes, used for sound transmission. The stapes was generally lost in other nothosaurs or marine reptiles during preservation. Scientists had predicted that if a stapes was found in a nothosaur, it would be thin and slender like in other species of this branch of the reptilian family tree. However, in B. jiyangshanensis it is thick and elongate, suggesting it had good hearing underwater.

“Perhaps this small, slow-swimming marine reptile had to be vigilante for large predators as it floated in the shallows, as well as being a predator itself,” says co-author Dr. Xiao-Chun Wu from the Canadian Museum of Nature.

References: Qing-Hua Shang, Xiao-Chun Wu & Chun Li (2020) A New Ladinian Nothosauroid (Sauropterygia) from Fuyuan, Yunnan Province, China, Journal of Vertebrate Paleontology, DOI: 10.1080/02724634.2020.1789651 link: https://www.tandfonline.com/doi/10.1080/02724634.2020.1789651#

Provided by Taylor & Francis

Eating Less Suppresses Liver Cancer Due To Fatty Liver (Oncology / Medicine)

Liver cancer from too much fat accumulation in the liver has been increasing in many countries including Japan. In order to change this unfortunate state of affairs, it is important to improve the prognosis of non-alcoholic fatty liver disease. Most often the cause of fatty liver is overeating and lack of exercise. Fatty liver is often improved through eating less, getting more exercise, and reducing body weight. Therefore, the research group led by Shinshu University graduate student Fangping Jia posed the question, “Can eating less also suppress liver cancer caused by fatty liver?”

30% dietary restriction suppresses liver tumors from fatty liver. ©Naoki Tanaka, Research Center for Social Systems, Shinshu University, Japan.

An international research team led by Shinshu University School of Medicine were able to show that reducing food intake by 30%, or eating until you are just 70% full is effective in reducing the likelihood of developing liver cancer from fatty liver. Fatty liver is a very common disease that can lead to liver cirrhosis and cancer. The team observed the incidence of fatty liver-related liver tumors in mice with the hepatitis C virus core gene and demonstrated the fall in the occurrence of liver cancer from 41% to 8% over a 15 month period, simply through dietary restriction.

Although there have been studies that showed the connection between obesity, fatty liver and hepatocellular carcinoma, the impact and mechanism of dietary restriction on cancer was not well understood before this study. Reducing food intake suppresses cell proliferation, oxidative/ER stress, inflammation, senescence and insulin signaling while increasing autophagy. Inflammation and oxidative/ER stress creates an environment in the body that is conducive to the development of abnormal cells. Autophagy is the mechanism in which the body cleans out damaged cells, reducing the likelihood of developing cancer.

Shinshu University School of Medicine Associate Professor Naoki Tanaka, corresponding author of the study hopes to eradicate liver cirrhosis and cancer from fatty liver through providing personalized dietary guidance and the promotion of the eating habit until you are just 70% full. In three other studies conducted by Associate Professor Tanaka using the same mouse model, the effect of the diet rich in cholesterol, saturated fats and trans-fats were shown to increase the incidence of liver tumors and elucidated the mechanism in which this occurs. Associate Professor Tanaka speculates that not only does the amount of fat intake matter, but the “quality” of dietary fats that lead to cancer. He hopes to elucidate this further in future studies.

Many previous studies have also shown that dietary restriction delayed the progression of cancer in humans through slowing down the rate of aging. There is a Chinese proverb that says, “to live a long and healthy life, eat until the stomach is 70 percent full.” Then you will live healthy, and it might lead to longevity.

References: http://dx.doi.org/10.1159/000508308

Provided by Shinshu University