Fossils found in museum drawer in Kenya belong to gigantic carnivore

Simbakubwa kutokaafrika, a gigantic carnivore known from most of its jaw, portions of its skull, and parts of its skeleton, was a hyaenodont that was larger than a polar bear.

Paleontologists at Ohio University have discovered a new species of meat-eating mammal larger than any big cat stalking the world today. Larger than a polar bear, with a skull as large as that of a rhinoceros and enormous piercing canine teeth, this massive carnivore would have been an intimidating part of the eastern African ecosystems occupied by early apes and monkeys.

In a new study published in the Journal of Vertebrate Paleontology, the researchers name Simbakubwa kutokaafrika, a gigantic carnivore known from most of its jaw, portions of its skull, and parts of its skeleton. The 22-million-year-old fossils were unearthed in Kenya decades ago as researchers canvassed the region searching for evidence of ancient apes. Specimens were placed in a drawer at the National Museums of Kenya and not given a great deal of attention until Ohio University researchers Dr. Nancy Stevens and Dr. Matthew Borths rediscovered them, recognizing their significance.

"Opening a museum drawer, we saw a row of gigantic meat-eating teeth, clearly belonging to a species new to science," says study lead author Borths. Borths was a National Science Foundation Postdoctoral Research Fellow with Stevens in the Department of Biomedical Sciences at Ohio University when the research was conducted, and is now Curator of the Division of Fossil Primates at the Duke Lemur Center at Duke University.

Simbakubwa is Swahili for "big lion" because the animal was likely at the top of the food chain in Africa, as lions are in modern African ecosystems. Yet Simbakubwa was not closely related to big cats or any other mammalian carnivore alive today. Instead, the creature belonged to an extinct group of mammals called hyaenodonts.

Hyaenodonts were the first mammalian carnivores in Africa. For about 45 million years after the extinction of the non-avian dinosaurs, hyaenodonts were the apex predators in Africa. Then, after millions of years of near-isolation, tectonic movements of the Earth's plates connected Africa with the northern continents, allowing floral and faunal exchange between landmasses. Around the time of Simbakubwa, the relatives of cats, hyenas, and dogs began to arrive in Africa from Eurasia.

As the relatives of cats and dogs were going south, the relatives of Simbakubwa were going north. "It's a fascinating time in biological history," Borths says. "Lineages that had never encountered each other begin to appear together in the fossil record."

The species name, kutokaafrika, is Swahili for "coming from Africa" because Simbakubwa is the oldest of the gigantic hyaenodonts, suggesting this lineage of giant carnivores likely originated on the African continent and moved northward to flourish for millions of years.

Ultimately, hyaenodonts worldwide went extinct. Global ecosystems were changing between 18 and 15 million years ago as grasslands replaced forests and new mammalian lineages diversified. "We don't know exactly what drove hyaenodonts to extinction, but ecosystems were changing quickly as the global climate became drier. The gigantic relatives of Simbakubwa were among the last hyaenodonts on the planet," remarks Borths.

"This is a pivotal fossil, demonstrating the significance of museum collections for understanding evolutionary history," notes Stevens, Professor in the Heritage College of Osteopathic Medicine at Ohio University and co-author of the study. "Simbakubwa is a window into a bygone era. As ecosystems shifted, a key predator disappeared, heralding Cenozoic faunal transitions that eventually led to the evolution of the modern African fauna."

This study was funded by grants from the National Science Foundation (EAR/IF-0933619; BCS-1127164; BCS-1313679; EAR-1349825; BCS-1638796; DBI-1612062), The Leakey Foundation, National Geographic Society (CRE), Ohio University Research Council, Ohio University Heritage College of Osteopathic Medicine, SICB and The Explorers Club.

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A history of the Crusades, as told by crusaders' DNA

This image shows the bones of the Crusaders found in a burial pit in Sidon, Lebanon.

History can tell us a lot about the Crusades, the series of religious wars fought between 1095 and 1291, in which Christian invaders tried to claim the Near East. But the DNA of nine 13th century Crusaders buried in a pit in Lebanon shows that there's more to learn about who the Crusaders were and their interactions with the populations they encountered. The work appears April 18 in The American Journal of Human Genetics.

The remains suggest that the soldiers making up the Crusader armies were genetically diverse and intermixed with the local population in the Near East, although they didn't have a lasting effect on the genetics of Lebanese people living today. They also highlight the important role ancient DNA can play in helping us understand historical events that are less well documented.

"We know that Richard the Lionheart went to fight in the Crusades, but we don't know much about the ordinary soldiers who lived and died there, and these ancient samples give us insights into that," says senior author Chris Tyler-Smith, a genetics researcher at the Wellcome Sanger Institute.

"Our findings give us an unprecedented view of the ancestry of the people who fought in the Crusader army. And it wasn't just Europeans," says first author Marc Haber, also of the Wellcome Sanger Institute. "We see this exceptional genetic diversity in the Near East during medieval times, with Europeans, Near Easterners, and mixed individuals fighting in the Crusades and living and dying side by side."

Archaeological evidence suggested that 25 individuals whose remains were found in a burial pit near a Crusader castle near Sidon, Lebanon, were warriors who died in battle in the 1200s. Based on that, Tyler-Smith, Haber, and their colleagues conducted genetic analyses of the remains and were able to sequence the DNA of nine Crusaders, revealing that three were Europeans, four were Near Easterners, and two individuals had mixed genetic ancestry.

Throughout history, other massive human migrations -- like the movement of the Mongols through Asia under Genghis Khan and the arrival of colonial Iberians in South America -- have fundamentally reshaped the genetic makeup of those regions. But the authors theorize that the Crusaders' influence was likely shorter-lived because the Crusaders' genetic traces are insignificant in people living in Lebanon today. "They made big efforts to expel them, and succeeded after a couple of hundred years," says Tyler-Smith.

This ancient DNA can tell us things about history that modern DNA can't. In fact, when the researchers sequenced the DNA of people living in Lebanon 2,000 years ago during the Roman period, they found that today's Lebanese population is actually more genetically similar to the Roman Lebanese.

"If you look at the genetics of people who lived during the Roman period and the genetics of people who are living there today, you would think that there was just this continuity. You would think that nothing happened between the Roman period and today, and you would miss that for a certain period of time the population of Lebanon included Europeans and people with mixed ancestry," says Haber.

These findings indicate that there may be other major events in human history that don't show up in the DNA of people living today. And if those events aren't as well-documented as the Crusades, we simply might not know about them. "Our findings suggest that it's worthwhile looking at ancient DNA even from periods when it seems like not that much was going on genetically. Our history may be full of these transient pulses of genetic mixing that disappear without a trace," says Tyler-Smith.

That the researchers were able to sequence and interpret the nine Crusaders' DNA at all was also surprising. DNA degrades faster in warm climates, and the remains studied here were burned and crudely buried. "There has been a lot of long-term interest in the genetics of this region, because it has this very strategic position, a lot of history, and a lot of migrations. But previous research has focused mainly on present-day populations, partly because recovering ancient DNA from warm climates is so difficult. Our success shows that studying samples in a similar condition is now possible because of advances in DNA extraction and sequencing technology," says Haber.

Next, the researchers plan to investigate what was happening genetically in the Near East during the transition from the Bronze Age to the Iron Age.

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Giant tortoises migrate unpredictably in the face of climate change

Galapagos giant tortoises are sometimes called gardeners of the Galapagos because they are responsible for long-distance seed dispersal. Their migration is key for many tree and plant species' survival.

Galapagos giant tortoises, sometimes called Gardeners of the Galapagos, are creatures of habit. In the cool dry season, the highlands of the volcano slopes are engulfed in cloud which allows the vegetation to grow despite the lack of rain. On the lower slopes, however, there is no thick fog layer, and vegetation is not available year round. Adult tortoises thus spend the dry season in the higher regions, and trek back to the lower, relatively warmer zones where there is abundant, nutritious vegetation when the rainy season begins.

The tortoises often take the same migration routes over many years in order to find optimal food quality and temperatures. The timing of this migration is essential for keeping their energy levels high, and climate change could disrupt a tortoise's ability to migrate at the right time.

In the Ecological Society of America's journal Ecology, researchers use GPS to track the timing and patterns of tortoise migration over multiple years.

"We had three main goals in the study," says Guillaume Bastille-Rousseau, lead author of the paper. "One was determining if tortoises adjust their timing of migration to current environmental conditions. Two, if so, what clues do they use to adjust the timing, and, three, what are the energetic consequences of migration mis-timing for tortoises?"

The researchers expected the migrations to be timed with current food and temperature conditions because many other migratory species operate that way. Bastille-Rousseau says "many animals, such as ungulates, can track current environmental conditions and migrate accordingly -- what researchers sometime refer to as surfing the green-wave."

Contrary to the researchers' expectations, however, migration is weakly associated with current conditions such as fog, rain, and temperature. For instance, if it is unseasonably arid, it appears the tortoises do not take that variation into account when deciding it is time to migrate. It is unclear at this point whether they are basing their migration decisions on memories of past conditions or if they are simply incorrectly assessing current local conditions.

Bastille-Rousseau says the team is surprised by the mismatch, stating "tortoise timing of migration fluctuated a lot among years, often by over two months. This indicates that migration for tortoises may not just be about foraging opportunities. For example, female tortoises have to make decisions related to nesting, and we still have a lot to learn about migration in giant tortoises."

Fortunately, this sub-optimal timing may not yet have critical impact on tortoise health. Potentially due to their long lives of up to 100 years and large body size, bad timing of migration has smaller consequences for giant tortoises compared to small, short lived animals. Giant tortoises can go up to a year without eating and survive, while other migrating species must eat more regularly to sustain their energy levels.

Giant tortoises are important ecosystem engineers in the Galapagos, responsible for long-distance seed dispersal, and their migration is key for many tree and plant species' survival. How the tortoises' variation in migration timing will affect the rest of the ecosystem is still unclear. Because tortoises do not seem to be tracking annual variation in environmental conditions, it is quite possible that the mistiming of migration will keep increasing in the future.

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Data mining digs up hidden clues to major California earthquake triggers

A historic image of quake damage in Long Beach, California, 1933.

A powerful computational study of southern California seismic records has revealed detailed information about a plethora of previously undetected small earthquakes, giving a more precise picture about stress in the earth's crust. A new publicly available catalog of these findings will help seismologists better understand the stresses triggering the larger earthquakes that occasionally rock the region.

"It's very difficult to unpack what triggers larger earthquakes because they are infrequent, but with this new information about a huge number of small earthquakes, we can see how stress evolves in fault systems," said Daniel Trugman, a post-doctoral fellow at Los Alamos National Laboratory and coauthor of a paper published in the journal Science today. "This new information about triggering mechanisms and hidden foreshocks gives us a much better platform for explaining how big quakes get started," Trugman said.

Crunching the Numbers

Trugman and coauthors from the California Institute of Technology and Scripps Institution of Oceanography performed a massive data mining operation of the Southern California Seismic Network for real quakes buried in the noise. The team was able to detect, understand, and locate quakes more precisely, and they created the most comprehensive earthquake catalog to date. The work identified 1.81 million quakes -- 10 times more earthquakes occurring 10 times more frequently than quakes previously identified using traditional seismology methods.

The team developed a comprehensive, detailed earthquake library for the entire southern California region, called the Quake Template Matching (QTM) catalog. They are using it to create a more complete map of California earthquake faults and behavior. This catalog may help researchers detect and locate quakes more precisely.

The team analyzed nearly two decades of data collected by the Southern California Seismic Network. The network, considered one of the world's best seismic systems, amasses a catalog of quakes from 550 seismic monitoring stations in the region. The SCSN catalog is based entirely on the traditional approach: manual observation and visual analysis. But Trugman says this traditional approach misses many weak signals that are indicators of small earthquakes.

Matching Templates Is Key

The team improved on this catalog with data mining. Using parallel computing, they crunched nearly 100 terabytes of data across 200 graphics processing units. Zooming in at high resolution for a 10-year period, they performed template matching using seismograms (waveforms or signals) of previously identified quakes. To create templates, they cut out pieces of waveforms from previously recorded earthquakes and matched those waveforms to patterns of signals recorded simultaneously from multiple seismic stations. Template matching has been done before, but never at this scale.

"Now we can automate it and search exhaustively through the full waveform archive to find signals of very small earthquakes previously hidden in the noise," Trugman explained.

Applying the templates found events quake precursors, foreshocks and small quakes that had been missed with manual methods. Those events often provide key physical and geographic details to help predict big quakes. The team also identified initiation sequences that reveal how quakes are triggered.

New details also revealed three-dimensional geometry and fault structures, which will support development of more realistic models.

Recently, Trugman and Los Alamos colleagues have applied machine learning to study earthquakes created in laboratory quake machines. That works has uncovered important details about earthquake behavior that may be used to predict quakes.

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How to defend the Earth from asteroids

The NEOWISE space telescope spotted Comet C/2013 US10 Catalina speeding by Earth on August 28, 2015. This comet swung in from the Oort Cloud, the shell of cold, frozen material that surrounds the Sun in the most distant part of the solar system far beyond the orbit of Neptune. NEOWISE captured the comet as it fizzed with activity caused by the Sun's heat. On November 15, 2015, the comet made its closest approach to the Sun, dipping inside the Earth's orbit; it is possible that this is the first time this ancient comet has ever been this close to the Sun. NEOWISE observed the comet in two heat-sensitive infrared wavelengths, 3.4 and 4.6 microns, which are color-coded as cyan and red in this image. NEOWISE detected this comet a number of times in 2014 and 2015; five of the exposures are shown here in a combined image depicting the comet's motion across the sky. The copious quantities of gas and dust spewed by the comet appear red in this image because they are very cold, much colder than the background stars.

A mere 17-20 meters across, the Chelyabinsk meteor caused extensive ground damage and numerous injuries when it exploded on impact with Earth's atmosphere in February 2013.

To prevent another such impact, Amy Mainzer and colleagues use a simple yet ingenious way to spot these tiny near-Earth objects (NEOs) as they hurtle toward the planet. She is the principal investigator of NASA's asteroid hunting mission at the Jet Propulsion Laboratory in Pasadena, California, and will outline the work of NASA's Planetary Defense Coordination Office this week at the American Physical Society April Meeting in Denver -- including her team's NEO recognition method and how it will aid the efforts to prevent future Earth impacts.

"If we find an object only a few days from impact, it greatly limits our choices, so in our search efforts we've focused on finding NEOs when they are further away from Earth, providing the maximum amount of time and opening up a wider range of mitigation possibilities," Mainzer said.

But it's a difficult task -- like spotting a lump of coal in the night's sky, Mainzer explained. "NEOs are intrinsically faint because they are mostly really small and far away from us in space," she said. "Add to this the fact that some of them are as dark as printer toner, and trying to spot them against the black of space is very hard."

Instead of using visible light to spot incoming objects, Mainzer's team at JPL/Caltech has leveraged a characteristic signature of NEOs -- their heat. Asteroids and comets are warmed by the sun and so glow brightly at thermal wavelengths (infrared), making them easier to spot with the Near-Earth Object Wide-field Infrared Survey Explorer (NEOWISE) telescope.

"With the NEOWISE mission we can spot objects regardless of their surface color, and use it to measure their sizes and other surface properties," Mainzer said.

Discovering NEO surface properties provides Mainzer and her colleagues an insight into how big the objects are and what they are made of, both critical details in mounting a defensive strategy against an Earth-threatening NEO.

For instance, one defensive strategy is to physically "nudge" an NEO away from an Earth impact trajectory. But to calculate the energy required for that nudge, details of NEO mass, and therefore size and composition, are necessary.

Astronomers also think that examining the composition of asteroids will help to understand how the solar system was formed.

"These objects are intrinsically interesting because some are thought to be as old as the original material that made up the solar system," Mainzer said. "One of the things that we have been finding is that NEOs are pretty diverse in composition."

Mainzer is now keen to leverage advances in camera technology to aid in the search for NEOs. "We are proposing to NASA a new telescope, the Near-Earth Object Camera (NEOCam), to do a much more comprehensive job of mapping asteroid locations and measuring their sizes," Mainzer said.

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Why lightning often strikes twice

Lightning often does strike twice.

In contrast to popular belief, lightning often does strike twice, but the reason why a lightning channel is 'reused' has remained a mystery. Now, an international research team led by the University of Groningen has used the LOFAR radio telescope to study the development of lightning flashes in unprecedented detail. Their work reveals that the negative charges inside a thundercloud are not discharged all in a single flash, but are in part stored alongside the leader channel at Interruptions. This occurs inside structures which the researchers have called needles. Through these needles, a negative charge may cause a repeated discharge to the ground. The results were published on 18 April in the science journal Nature.

Needles

"This finding is in sharp contrast to the present picture, in which the charge flows along plasma channels directly from one part of the cloud to another, or to the ground," explains Olaf Scholten, Professor of Physics at the KVI-CART institute of the University of Groningen. The reason why the needles have never been seen before lies in the 'supreme capabilities' of LOFAR, adds his colleague Dr Brian Hare, first author of the paper: "These needles can have a length of 100 meters and a diameter of less than five meters, and are too small and too short-lived for other lightning detections systems."

Low Frequency Array (LOFAR) is a Dutch radio telescope consisting of thousands of rather simple antennas spread out over Northern Europe. These antennas are connected with a central computer through fiber-optic cables, which means that they can operate as a single entity. LOFAR is developed primarily for radio astronomy observations, but the frequency range of the antennas also makes it suitable for lightning research, as discharges produce bursts in the VHF (very high frequency) radio band.

Inside the cloud

For the present lightning observations, the scientists have used only the Dutch LOFAR stations, which cover an area of 3,200 square kilometers. This new study analyzed the raw time-traces (which are accurate to one nanosecond) as measured in the 30-80 MHz band. Brian Hare: "These data allow us to detect lightning propagation at a scale where, for the first time, we can distinguish the primary processes. Furthermore, the use of radio waves allows us to look inside the thundercloud, where most of the lightning resides."

Lightning occurs when strong updrafts generate a kind of static electricity in large cumulonimbus clouds. Parts of the cloud become positively charged and others negatively. When this charge separation is large enough, a violent discharge happens, which we know as lightning. Such a discharge starts with a plasma, a small area of ionized air hot enough to be electrically conductive. This small area grows into a forked plasma channel that can reach lengths of several kilometers. The positive tips of the plasma channel collect negative charges from the cloud, which pass through the channel to the negative tip, where the charge is discharged. It was already known that a large amount of VHF emissions is produced at the growing tips of the negative channels while the positive channels show emissions only along the channel, not at the tip.

A new algorithm

The scientists developed a new algorithm for LOFAR data, allowing them to visualize the VHF radio emissions from two lightning flashes. The antenna array and the very precise time stamp on all the data allowed them to pinpoint the emission sources with unprecedented resolution. "Close to the core area of LOFAR, where the antenna density is highest, the spatial accuracy was about one meter," says Professor Scholten. Furthermore, the data obtained was capable of localizing 10 times more VHF sources than other three-dimensional imaging systems, with a temporal resolution in the range of nanoseconds. This resulted in a high-resolution 3D image of the lightning discharge.

Break

The results clearly show the occurrence of a break in the discharge channel, at a location where needles are formed. These appear to discharge negative charges from the main channel, which subsequently re-enter the cloud. The reduction of charges in the channel causes the break. However, once the charge in the cloud becomes high enough again, the flow through the channel is restored, leading to a second discharge of lightning. By this mechanism, lightning will strike in the same area repeatedly.

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Asteroids help scientists to measure the diameters of faraway stars

When an asteroid passes in front of a star, the resulting diffraction pattern (here greatly exaggerated) can reveal the star's angular size.

Using the unique capabilities of telescopes specialised on cosmic gamma rays, scientists have measured the smallest apparent size of a star on the night sky to date. The measurements with the Very Energetic Radiation Imaging Telescope Array System (VERITAS) reveal the diameters of a giant star 2674 light-years away and of a sun-like star at a distance of 700 light-years. The study establishes a new method for astronomers to determine the size of stars, as the international team led by Tarek Hassan from DESY and Michael Daniel from the Smithsonian Astrophysical Observatory (SAO) reports in the journal Nature Astronomy.

Almost any star in the sky is too far away to be resolved by even the best optical telescopes. To overcome this limitation, the scientists used an optical phenomenon called diffraction to measure the star's diameter. This effect illustrates the wave nature of light, and occurs when an object, such as an asteroid, passes in front of a star. "The incredibly faint shadows of asteroids pass over us everyday," explained Hassan. "But the rim of their shadow isn't perfectly sharp. Instead, wrinkles of light surround the central shadow, like water ripples." This is a general optical phenomenon called a diffraction pattern and can be reproduced in any school lab with a laser hitting a sharp edge.

The researchers used the fact that the shape of the pattern can reveal the angular size of the light source. However, different from the school lab, the diffraction pattern of a star occulted by an asteroid is very hard to measure. "These asteroid occultations are hard to predict," said Daniel. "And the only chance to catch the diffraction pattern is to make very fast snapshots when the shadow sweeps across the telescope." Astronomers have measured the angular size of stars this way that were occulted by the moon. This method works right down to angular diameters of about one milliarcsecond, which is about the apparent size of a two-cent coin atop the Eiffel Tower in Paris as seen from New York.

However, not many stars in the sky are that "big." To resolve even smaller angular diameters, the team employed Cherenkov telescopes. These instruments normally watch out for the extremely short and faint bluish glow that high-energy particles and gamma rays from the cosmos produce when they encounter and race through Earth's atmosphere. Cherenkov telescopes do not produce the best optical images. But thanks to their huge mirror surface, usually segmented in hexagons like a fly's eye, they are extremely sensitive to fast variations of light, including starlight.

Using the four large VERITAS telescopes at the Fred Lawrence Whipple Observatory in Arizona, the team could clearly detect the diffraction pattern of the star TYC 5517-227-1 sweep past as it was occulted by the 60-kilometre asteroid Imprinetta on 22 February 2018. The VERITAS telescopes allowed to take 300 snapshots every second. From these data, the brightness profile of the diffraction pattern could be reconstructed with high accuracy, resulting in an angular, or apparent, diameter of the star of 0.125 milliarcseconds. Together with its distance of 2674 light-years, this means the star's true diameter is eleven times that of our sun. Interestingly, this result categorises the star whose class was ambiguous before as a red giant star.

The researchers repeated the feat three months later on 22 May 2018, when asteroid Penelope with a diameter of 88 kilometres occulted the star TYC 278-748-1. The measurements resulted in an angular size of 0.094 milliarcseconds and a true diameter of 2.17 times that of our sun. This time the team could compare the diameter to an earlier estimate based on other characteristics of the star that had placed its diameter at 2.173 times the solar diameter -- an excellent match, although the earlier estimate was not based on a direct measurement.

"This is the smallest angular size of a star ever measured directly," Daniel emphasised. "Profiling asteroid occultations of stars with Cherenkov telescopes delivers a ten times better resolution than the standard lunar occultation method. Also, it is at least twice as sharp as available interferometric size measurements." The uncertainty of these measurements are about ten per cent, as the authors write. "We expect this can be notably improved by optimising the set-up, for example narrowing the wavelength of the colours recorded," said Daniel. Since different wavelengths are diffracted differently, the pattern is smeared out if too many colours are recorded at the same time.

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Common sleep myths compromise good sleep and health

People often say they can get by on five or fewer hours of sleep, that snoring is harmless, and that having a drink helps you to fall asleep.

These are, in fact, among the most widely held myths about sleeping that not only shape poor habits, but may also pose a significant public health threat, according to a new study publishing online in Sleep Health on April 16.

Researchers from NYU School of Medicine reviewed more than 8,000 websites to identify the 20 most common assumptions about sleep. With a team of sleep medicine experts, they ranked them based on whether each could be dispelled as a myth or supported by scientific evidence, and on the harm that the myth could cause.

"Sleep is a vital part of life that affects our productivity, mood, and general health and well-being," says study lead investigator, Rebecca Robbins, PhD, a postdoctoral research fellow in the Department of Population Health at NYU Langone Health. "Dispelling myths about sleep promotes healthier sleep habits which, in turn, promote overall better health."

The claim by some people that they can get by on five hours of sleep was among the top myths researchers were able to dispel based on scientific evidence. They say this myth also poses the most serious risk to health from long-term sleep deficits. To avoid the effects of this falsehood and others identified in this study, such as the value of taking naps when you routinely have difficulty sleeping overnight, Robbins and her colleagues suggest creating a consistent sleep schedule and spending more time, at least seven hours, asleep.

Another common myth relates to snoring. And while Robbins says snoring can be harmless, it can also be a sign of sleep apnea, a potentially serious sleep disorder in which breathing starts and stops over the course of the night. The authors encourage patients not to dismiss loud snoring, but rather to see a doctor since this sleep behavior may lead to heart stoppages or other illnesses.

The study authors also found sufficient evidence in published studies that, despite beliefs to the contrary, drinking alcoholic beverages before bed is indeed unhealthy for sleep. According to experts, alcohol reduces the body's ability to achieve deep sleep, which people need to function properly.

"Sleep is important to health, and there needs to be greater effort to inform the public regarding this important public health issue," says study senior investigator Girardin Jean Louis, PhD, a professor in the departments of Population Health and Psychiatry at NYU Langone. "For example, by discussing sleep habits with their patients, doctors can help prevent sleep myths from increasing risks for heart disease, obesity, and diabetes."

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Coelacanth reveals new insights into skull evolution

This is the overall anterolateral view of the skull of the Coelacanth's foetus. The brain is in yellow.

An international team of researchers presents the first observations of the development of the skull and brain in the living coelacanth Latimeria chalumnae. Their study, published in Nature, provides new insights into the biology of this iconic animal and the evolution of the vertebrate skull.

The coelacanth Latimeria is a marine fish closely related to tetrapods, four-limbed vertebrates including amphibians, mammals and reptiles. Coelacanths were thought to have been extinct for 70 million years, until the accidental capture of a living specimen by a South African fisherman in 1938. Eighty years after its discovery, Latimeria remains of scientific interest for understanding the origin of tetrapods and the evolution of their closest fossil relatives -- the lobe-finned fishes.

One of the most unusual features of Latimeria is its hinged braincase, which is otherwise only found in many fossil lobe-finned fishes from the Devonian period (410-360 million years ago). The braincase of Latimeria is completely split into an anterior and posterior portion by a joint called the "intracranial joint." In addition, the brain lies far at the rear of the braincase and takes up only 1% of the cavity housing it. This mismatch between the brain and its cavity is totally unequalled among living vertebrates. How the coelacanth skull grows and why the brain remains so small has puzzled scientists for years. To answer these questions, researchers studied specimens at different stages of cranial development from several public natural history collections.

Although many specimens of adult coelacanths are available in natural history collections, earlier life stages such as fetuses are extremely rare. Scientists hence used state-of-the-art imaging techniques to visualize the internal anatomy of the specimens without damaging them. They notably digitalized a 5 cm-long fetus, the earliest developmental stage available for Latimeria, with synchrotron X-ray microtomography at the European Synchrotron (ESRF). Over the last two decades, the ESRF has developed unique expertise in designing non-invasive techniques widely used for evolutionary biology studies.

In addition, the researchers also imaged other stages with a powerful Magnetic Resonance Imaging (MRI) scanner at the Brain and Spine Institute (Paris, France), and a conventional X-ray micro-CTscan at the Muséum national d'Histoire naturelle (Paris, France). These data were used to generate detailed 3D models, which allowed scientists to describe how the form of the skull, the brain and the notochord (a tube extending below the brain and the spinal cord in the early stages of life) changes from a fetus to an adult.

They also observed how these structures are positioned relative to each other at each stage, and compared their observations with what is known about the formation of the skull in other vertebrates.

In contrast to most other vertebrates, where the notochord is replaced by the vertebral column early in embryonic development, the notochord expands considerably in Latimeria. The dramatic enlargement of the notochord likely influences the patterning of the braincase, and might underpin the formation of the intracranial joint. The brain might also be affected by the enlargement of the notochord, as relative size dramatically decreases during development.

These results illuminate for the first time the development of the living coelacanth skull and brain, and open up new avenues for research on the evolution of the vertebrate head.

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New form of laser for sound

The optical laser has grown to a $10 billion global technology market since it was invented in 1960, and has led to Nobel prizes for Art Ashkin for developing optical tweezing and Gerard Mourou and Donna Strickland for work with pulsed lasers. Now a Rochester Institute of Technology researcher has teamed up with experts at the University of Rochester to create a different kind of laser -- a laser for sound, using the optical tweezer technique invented by Ashkin.

In the newest issue of Nature Photonics, the researchers propose and demonstrate a phonon laser using an optically levitated nanoparticle. A phonon is a quantum of energy associated with a sound wave and optical tweezers test the limits of quantum effects in isolation and eliminates physical disturbances from the surrounding environment. The researchers studied the mechanical vibrations of the nanoparticle, which is levitated against gravity by the force of radiation at the focus of an optical laser beam.

"Measuring the position of the nanoparticle by detecting the light it scatters, and feeding that information back into the tweezer beam allows us to create a laser-like situation," said Mishkat Bhattacharya, associate professor of physics at RIT and a theoretical quantum optics researcher. "The mechanical vibrations become intense and fall into perfect sync, just like the electromagnetic waves emerging from an optical laser."

Because the waves emerging from a laser pointer are in sync, the beam can travel a long distance without spreading in all directions -- unlike light from the sun or from a light bulb. In a standard optical laser the properties of the light output are controlled by the material from which the laser is made. Interestingly, in the phonon laser the roles of light and matter are reversed -- the motion of the material particle is now governed by the optical feedback.

"We are very excited to see what the uses of this device are going to be -- especially for sensing and information processing given that the optical laser has so many, and still evolving, applications," said Bhattacharya. He also said the phonon laser promises to enable the investigation of fundamental quantum physics, including engineering of the famous thought experiment of Schrödinger's cat, which can exist at two places simultaneously.

From Science Daily