Did a Stroke Kill Leonardo da Vinci?

Leonardo Da Vinci may have suffered from a recurrent stroke that considerably reduced his motor activity in the last two years of his life and eventually caused his death, according to a historic viewpoint published in the June issue of The Lancet Neurology.

The study, carried out by two Italian medical doctors, examined ancient sources to reconstruct Da Vinci’s health from 1517 until his death in 1519 aged 67.

“The diary of Louis d’Aragona’s journey, written by Antonio de Beatis, tells us that Leonardo had a right hand’s paralysis when he was 65 years old,” Antonio Perciaccante, at the department of medicine of Gorizia hospital, told Discovery News.

“Nevertheless, the ancient document reports Da Vinci continued to paint, draw, and teach,” he added.

Perciaccante and co-author Alessia Coralli, at the department of surgery of Civita Castellana hospital, noted the account indicates that Leonardo suffered from a right hand’s paralysis with partial physical, but not cognitive, consequences.

Da Vinci’s health must have however deteriorated, following the report of 15th-century painter, architect and writer Giorgio Vasari.

In his 1550 book “Lives of the Artists,” Vasari described Leonardo as a sick and bedridden man, unable to stand up without being “supported by the arms of his servants and his friends.”

“He was ill for many months,” Vasari wrote.

According to Perciaccante and Coralli, something happened that compromized the general autonomy of the Renaissance genius.

“Our hypothesis is that a first stroke caused the hand’s paralysis. Other stroke events then followed, deteriorating Da Vinci’s health and motor activity,” Perciaccante said.

Da Vinci died in Amboise, France, on May 2, 1519, in the arms of King Francis I of France, according to Vasari. He attributed the death to a “paroxysm.”

“The term refers to a sudden attack or increase of symptoms of a disease that often recurs. Thus, it can adequately describe a stroke,” Perciaccante said.

According to the researchers, the hypothesis of a recurrent stroke is supported by medical literature.

Read more at Discovery News

Earth's Thin Early Atmosphere Revealed in Bubbles

Air bubbles trapped in 2.7 billion-year-old lava flows in the Pilbara suggest the Earth’s atmosphere weighed less than half that of today and was far thinner than previously thought.

The discovery has forced a rethink of how the Earth managed to stay relatively ice-free during that period, despite the sun being much cooler than it is today.

In a study published today in Nature Geoscience, researchers analysed the relative sizes of air bubbles across ancient lava flows along the Beasley River in Western Australia’s Pilbara region.

The lava flows — discovered by Australian researcher Dr Tim Blake, then at the University of Western Australia — bear distinctive features such as lava “toes” with cracked, glassy rinds, which suggested the molten rock once flowed over a beach.

Astrobiologist Professor David Catling, one of the study’s authors from the University of Washington, said the Sun was roughly 20 percent less luminous 2.7 billion years ago, so if Earth had an atmosphere similar to today it would have been covered in ice. Yet similar conditions as today prevailed.

“All the signs are that it wasn’t that different, in terms of the climate system from today; there was rainfall and rivers, there might have been polar ice caps, but it was warm enough ... for the whole world (not) to be covered in ice,” Professor Catling said.

Until now, the prevailing hypothesis to explain these warmer-than-expected conditions was that the atmosphere at that time had been much thicker, which would have insulated the Earth.

But the bubbles preserved in the rock at what would have been sea level paint a very different picture of the Earth’s atmospheric pressure during the Archean period, which extends from the formation of the Earth’s crust 4 billion years ago to around 2.5 billion years ago.

The researchers compared the size of air bubbles trapped at the surface of the lava — whose size is constrained only by air pressure — and those at the base, which are constrained both by atmospheric pressure and the weight of the lava itself, to work out the air pressure at the time the lava flow happened.

“We found the atmosphere basically was a lot thinner back then and weighed less than half of what it does today,” Dr Catling said.

He said the finding raised the question of what exactly was keeping the Earth warm enough for liquid water to flow.

“The first thing is the air must have had a lot of proportions of greenhouse gases like carbon dioxide or methane, so even though the air is thin if you stuff it full enough of greenhouse gases it can still warm the Earth,” he said.

Read more at Discovery News

Atomic Oxygen Detected on Mars

A specially-equipped 747 has detected atomic oxygen in Mars’ upper atmosphere, NASA reported, marking the first time that the space agency has made that observation in four decades.

The California-based NASA plane that made the measurements is called the Stratospheric Observatory for Infrared Astronomy, or SOFIA. NASA reports that using an instrument on board the plane, they found the atomic oxygen in the planet’s mesosphere, which is its upper atmosphere— but only saw about half of what they thought they would.

“Atomic oxygen in the Martian atmosphere is notoriously difficult to measure,” Pamela Marcum, a project scientist with SOFIA, said in a statement. “To observe the far-infrared wavelengths needed to detect atomic oxygen, researchers must be above the majority of Earth’s atmosphere and use highly sensitive instruments, in this case a spectrometer. SOFIA provides both capabilities.”

The SOFIA airplane that made the measurements of Mars conducts its research while flying at an altitude of between 37,000 and 45,000 feet.

On Earth, two oxygen atoms join together to form O2, which is what we breathe. Atomic oxygen, however, is just a single oxygen atom. When atomic oxygen was last detected in the atmosphere of the red planet, it was because of the Viking and Mariner missions.

“Atomic oxygen affects how other gases escape Mars and therefore has a significant impact on the planet’s atmosphere,” NASA said.

From Discovery News

Intense wind found in the neighborhood of a black hole

an artistic view of the accretion disc surrounding the black hole V404 Cygni, where the intense wind detected by GTC becomes evident.

An international team of astrophysicists, including Professor Phil Charles from the University of Southampton, have detected an intense wind from one of the closest known black holes to the Earth.

During observations of V404 Cygni, which went into a bright and violent outburst in June 2015 after more than 25 years of quiescence, the team began taking optical measurements of the black hole's accretion disc using the 10.4m Gran Telescopio CANARIAS (GTC) -- the biggest optical-infrared telescope in the world, situated at the Roque de los Muchachos Observatory (Garafía, La Palma) in the Canary Islands.

The results, which are published today in Nature, show the presence of a wind of neutral material (unionised hydrogen and helium), which is formed in the outer layers of the accretion disc, regulating the accretion of material by the black hole. This wind, detected for the first time in a system of this type, has a very high velocity (3,000 kilometres per second) so that it can escape from the gravitational field around the black hole.

Professor Charles, from Physics and Astronomy at the University of Southampton, said: "Its presence allows us to explain why the outburst, in spite of being bright and very violent, with continuous changes in luminosity and ejections of mass in the form of jets, was also very brief, lasting only two weeks."

At the end of this outburst the GTC observations revealed the presence of a nebula formed from material expelled by the wind. This phenomenon, which has been observed for the first time in a black hole, also allows scientists to estimate the quantity of mass ejected into the interstellar medium.

Teo Muñoz Darias, a researcher at the Instituto de Astrofísica de Canarias (IAC) and the lead author of the study (and also a former Marie Curie Fellow at Southampton), said: "The brightness of the source and the large collecting area of the GTC allowed us not only to detect the wind, but also to measure the variation of its properties on time-scales of minutes. The database obtained is probably the best ever observed for an object of this kind.

"This outburst of V404 Cygni, because of its complexity and because of the high quantity and quality of the observations, will help us understand how black holes swallow material via their accretion discs."

"We think that what we have observed with the GTC in V404 Cygni happens, at least, in other black holes with large accretion discs," concluded Professor Charles and Jorge Casares from IAC, two of the discoverers of V404 Cygni in 1992, and co-authors of the study.

V404 Cygni is a black hole within a binary system located in the constellation of Cygnus. In such systems, of which less than 50 are known, a black hole of around 10 times the mass of the Sun is swallowing material from a very nearby star, its companion star. During this process material falls onto the black hole and forms an accretion disc, whose hotter, innermost zones emit in X-rays. In the outer regions, however, we can study the disc in visible light, which is the part of the spectrum observable with the GTC.

V404 Cygni, at only 8,000 light years away, is one of the closest known black holes to the Earth, and has a particularly large accretion disc (with a radius of about ten million kilometres), making its outbursts especially bright at all wavelengths (X-rays, visible, infrared and radio waves).

On 15 June 2015, V404 Cygni went into outburst after a quiescence of over 25 years. During this period its brightness increased one million fold in a few days, becoming the brightest X-ray source in the sky. The GTC began taking spectroscopic observations on 17 June via the activation of a "target of opportunity" programme, designed by IAC researchers for this kind of event.

Read more at Science Daily

Leprosy Threatens Red Squirrels in UK

A squirrel native to Britain that was already in trouble now needs help with another threat: leprosy.

The disease results in swelling in the animal’s snout, feet and ears, as well as hair loss, and wildlife officials in the United Kingdom are launching a study to figure out how it is being transmitted, according to the Daily Mail.

The major problem for the ruddy creatures is that their historic turf has been overrun by grey squirrels introduced from the United States. There are just an estimated 140,000 red squirrels left in the U.K., compared to some 2.5 million grey squirrels, according to England’s forestry commission.

Leprosy was first discovered in the U.K.’s red squirrels in Scotland in 2014, although experts think it has been around for a long time – perhaps hundreds of years — and simply gone undiagnosed.

According to Dorset Wildlife Trust, which will participate in the study, the leprosy bacteria is "widespread" among the squirrels but "neglible" in terms of risk to humans. Scientists with the organization aren't sure yet how the disease is being transmitted among the squirrels.

Ground zero for the leprosy study will be Brownsea Island, a site thought to be a hotbed for the disease and one that will enable the scientists to study it in a contained setting.

Researches from the University of Edinburgh, alongside local wildlife managers from Brownsea Island, will conduct the study using humane traps. They'll capture the animals long enough for blood tests and basic health exams to be administered, before returning them to the wild.

From Discovery News

520-Million-Year-Old Fossil Larva Preserved in 3D

If you think finding a needle in a haystack sounds challenging, try searching for fossils the size of fingernail clippings in massive slabs of rock.

But that’s just what a team of scientists is doing at a site in Chengjiang, China. And they recently struck a fossil jackpot, discovering an extremely rare arthropod larva fossil measuring a mere 0.08 inches (2 millimeters) long.

The fossil, estimated to be 520 million years old, was preserved in 3D, presenting the researchers with an exceptional level of detail for this very early stage of the creature’s development. It also provided them with a first glimpse of ancestral larval forms in arthropods, the invertebrate animal group with exoskeletons and segmented bodies that includes arachnids, crustaceans and insects.

The larva has a segmented body, with two large structures on its head, four pairs of branching legs and three additional pairs of legs that are much less developed. Its posterior is tipped with a “dagger-like” appendage, framed by two triangular forms resembling paddles, which the scientists suggest may have been used for swimming.

This is the first fossil of its kind to be found at Chengjiang since the site’s discovery in 1984, according to Yu Liu, the study’s lead author and a postdoctoral researcher at the Ludwig-Maximilians-Universität in Munich.

The researchers identified the tiny fossil as a known species — Leanchoilia illecebrosa, a member of the “short great appendage arthropods,” which earned their name due to the large claw-like structures attached to their heads, likely used for feeding or for sensing their environment.

In fact, it was the shape of those appendages in the larva fossil that helped the scientists with their identification, Liu told Live Science in an email.

But compared to adult forms, other limbs in the fossil were not as well developed. This told the scientists that the new discovery represented an early larval stage, Liu said.

Hidden in rock

Finding fossils this small is no easy task. It begins with removing large slabs of rock, splitting them into somewhat smaller slabs, and then reviewing them with a magnifying lens to see if there might be “something interesting” preserved in them, according to Liu.

“As you may imagine, the chance of finding a fossil is not very high,” Liu told Live Science. “In most cases, you get one fossil after separating tens of slabs. The chance of finding a GOOD fossil is even lower. You need to separate hundreds or even thousands of slabs for that.”

Such tiny and delicate specimens like this one can’t be isolated from the rocky material around them with the methods traditionally used for chipping out larger fossils. Paleontologists use microphotography and scanning technology rather than picks, drills, or chisels to “penetrate” the rock and show them the remains of once-living animals preserved inside.

3D surprise

And finding such a small fossil preserved in 3D was unexpected and exciting, Liu said. Micro computed tomography — micro-CT scans — of the larva offered a highly detailed picture of its body, with an interesting surprise as a result.

This particular larva’s body type — one in which body segments are added as the creature grows to adulthood — was already thought to be typical for modern crustaceans, Liu said. But, finding one this far back in the fossil record hints that this was a feature in all other arthropod ancestors, as well.

Read more at Discovery News

King Tut Tomb Secret Chambers? Not So Fast

The theory that King Tut’s tomb contains secret chambers has been greeted with skepticism at an international conference in Cairo dedicated to the boy king.

The growing doubts prompted the Egyptian antiquities minister Khaled El-Enany to reassure that no physical exploration inside the tomb is planned at this time.

“I will not make any drills until I am sure 100 percent that there is a cavity behind the wall,” El-Enany said.

Already last month, El-Enany appeared to cool down the expectations that rose after his predecessor Mamdouh Eldamaty revealed there was a “90 percent chance” that King Tut’s tomb concealed two chambers.

Indeed, Eldamaty had confirmed that analysis of radar scans carried out by Japanese specialist Hirokatsu Watanabu revealed two hidden spaces on the north and eastern walls that could contain metal or organic material.

Begun last summer, the investigation inside King Tut’s burial follows a claim by Nicholas Reeves, a British Egyptologist at the University of Arizona. He believes the hidden chambers contain the remains, and possibly the intact grave goods, of Queen Nefertiti, wife of the “heretic” monotheistic pharaoh Akhenaten, Tutankhamun’s father.

Reeves speculated that the tomb of King Tut was not ready when he died unexpectedly at 19 in 1323 B.C.; consequently, he was buried in a rush in what was originally the tomb of Nefertiti, who had died 10 years earlier.

Friederike Seyfried, director of the Egyptian Museum and Papyri in Berlin, described Reeves’s claim as a mere hypothesis and argued the radar survey can’t prove the existence of a hidden tomb.

“The sudden death of the boy-king led the tomb’s builders to finish the tomb quickly and close it up, which is why a cavity was found,” he told Ahram Online.

According to former Antiquities Minister Zahi Hawass, “the project wasn’t done scientifically at all. ” He stressed that radar scan is not sufficient alone to make a new archaeological discovery.

“In my entire career, I have never come across any discovery in Egypt made by radar scans,” Hawass said.

He noted that a follow up radar scan failed to replicate Watanabu’s promising results.

“If there is any masonry or partition wall, the radar signal should show an image,” the National Geographic reported him to say.

“We don’t have this, which means there is nothing there,” Hawass said.

Read more at Discovery News

Pluto's Moon Coated in Nearly Pure Water Ice

Discovered in June 2005, Pluto’s outermost moon Hydra is thought to have formed four billion years ago during a massive impact event that created Pluto and Charon.

Despite its age, this 31-mile-wide moon appeared remarkably clean and bright in New Horizons images during the spacecraft’s historic close pass through the Pluto system in July 2015.

Scientists’ initial speculation was proved right when data from the spacecraft was analyzed and revealed that Hydra, like its name, is covered in nearly pure water ice.

Measured with the Linear Etalon Imaging Spectral Array (LEISA) on New Horizons’ Ralph instrument, the spectral signature of water ice on Hydra is even stronger than that seen on Pluto’s much larger satellite Charon, indicating a surface coated with bigger ice particles and less dusty, dark material.

Spectral data gathered by New Horizons shows Hydra to be coated in a much more pure ice material than the larger Charon.

“Perhaps micrometeorite impacts continually refresh the surface of Hydra by blasting off contaminants,” said Simon Porter, a New Horizons science team member from the Southwest Research Institute (SwRI) in Boulder, Colorado. “This process would have been ineffective on the much larger Charon, whose much stronger gravity retains any debris created by these impacts.”

Read more at Discovery News

Scientists cite evidence that mosasaurs were warm-blooded

Fossilize teeth of a mosasaur (stock image). Mosasurs were large aquatic reptiles that went extinct at the end of the Cretaceous period, about 66 million years ago.

Mosasaurs -- an extinct group of aquatic reptiles that thrived during the Late Cretaceous period -- possibly were "endotherms," or warm-blooded creatures, a paper co-written by a UA professor suggests.

Dr. Alberto Perez-Huerta's paper on endothermic mosasaurs -- co-written with now-graduated doctoral student Dr. T. Lynn Harrell Jr. and Dr. Celina Suarez of the University of Arkansas -- was published in a March issue of Palaeontology, a journal published by the Palaeontological Association.

Mosasurs were large aquatic reptiles that went extinct at the end of the Cretaceous period, about 66 million years ago. The paper focuses on a debate in the paleontological community over how mosasaurs employed "thermaregulation," or how they controlled their body heat -- whether mosasaurs were endotherms (warm-blooded) or ectotherms, cold-blooded creatures taking their body temperature from the surrounding sea.

A paper published in 2010 suggested that mosasaurs were ectotherms, but Harrell and Perez-Huerta thought otherwise.

"There was a paper published in Science in 2010 reporting the thermoregulation in marine reptiles at the time of the dinosaurs focusing on the iconic extinct taxa: ichthyosaurs, plesiosaurs and mosasaurs," said Perez-Huerta, a UA associate professor of geology. "This conclusion bothered me a bit because there was not a warm-blooded member organism used for comparison, and we know that size can matter in terms of thermoregulation."

The study by Harrell (lead author), Perez-Huerta and Suarez used an oxygen isotope analysis on mosasaurs fossils in the collection of UA's Alabama Museum of Natural History and compared them to fossils of known cold-blooded animals, such as fish and turtles, from the same period, as well as the bones of such contemporary warm-blooded organisms represented by birds -- "true" endotherms.

"Lynn came up with good ideas for two chapters of his dissertation, already published as well," Perez-Huerta said. "We discussed looking for endothermy in mosasaurs given his knowledge on this group of extinct marine reptiles, the large collections of these fossil organisms in the Alabama Museum of Natural History and the scientific controversy related to the Science paper."

The study states that mosasurs' body-temperatures compared to the temperatures of modern, warm-blooded sea birds, suggesting that mosausurs were indeed warm-blooded. The study found that this tendency toward higher body temperature held despite the size of the particular mosasur genus or species -- body size (gigantothermy) didn't matter.

"The findings of the present study support that mosasaurs were able to maintain a higher internal temperature independent of the ambient seawater temperature and were likely endotherms, with values closer to contemporaneous fossil and modern birds and higher than fish and turtles," the researchers said. "Although there are small differences of body temperature among mosasaur genera, these are independent of size, and thus inferred body mass, suggesting that mosasaurs were not gigantotherms."

Perez-Huerta noted that the study was possible thanks to the Alabama Museum of Natural History's extensive collection.

Read more at Science Daily

Simulation of prehistoric population dynamics using current topographical satellite data

This image shows a) the current British population density, b) the genetic map, c) the habitability of the landmass, and d) simulated distribution in population after 2,000 steps.

In a recent breakthrough, scientists from the Tata Institute of Fundamental Research, and the Centre for Excellence in Basic Sciences, Mumbai, demonstrate an accurate method to simulate prehistoric movements of people based upon current topographical satellite data. Recently published in the journal PLOS ONE, population dynamics of prehistoric human migration into the island comprising England, Scotland and Wales was simulated by applying a diffusion equation tempered by geographical data determined from satellite-based information.

Importantly, these findings are validated by recently-available genetic data. This method may prove useful in determining early human population dynamics even when no genetic information is available.

Movement of people in prehistoric times was almost entirely determined by geography and human needs, both deterministic parameters when small populations move into unoccupied areas where conflicts and large group dynamics are not important. The early period of human migration into the British Isles provides a near-ideal laboratory which, because of its relative geographical isolation, may allow some insights into the complex dynamics of early human migration and interaction.

Commenting on the simulation used in this study, Professor Vahia, the lead scientist of this work, says, "Our simulation code is based on human affinity to habitable land, as defined by availability of water sources, altitude, and flatness of land. These parameters temper the diffusion of people and allow us to follow their path of migration." The initial entry points of people into the main British island were determined using data from the megalithic period. Topographical and hydro-shed data from satellite databases was used to define habitability, based on distance from water bodies, flatness of the terrain, and altitude above sea level.

Read more at Science Daily