среда, 1 августа 2018 г.

Frozen Herpes Viruses are biological machines built to spread…

Frozen Herpes

Viruses are biological machines built to spread infection. They trick infected cells into replicating their genetic material, pumping it into shell-like containers called capsids ready to infect more cells. Different herpes viruses can cause everything from cold-sores and inherited disorders, to some forms of cancer, yet they share similar traits. This computer reconstruction of the herpes simplex virus is based on images of frozen virus particles captured using cryogenic electron microscopy. Shades of pink and purple highlight the virus’ ‘portal’, where genetic material pumps into the capsid – from the side (top) or looking up (below). Each pair of images is presented as a sort of ‘magic eye’ picture, or 3D stereogram. Understanding how the herpes machinery works at vital stages of infection may help to design new drugs that point the immune system in the right direction, combatting infections with this pretty pathogen that can last a lifetime.

Written by John Ankers

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jason-1971: Hendre Waelod (Allor Molloch) Burial Chamber North…


Hendre Waelod (Allor Molloch) Burial Chamber North Wales

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HiPOD (1 August 2018): An Inverted Channel on Elevated Terrain  …

HiPOD (1 August 2018): An Inverted Channel on Elevated Terrain 

   – Interesting fluvial processes that might help improve our understanding of the deposits in the Medusae Fossae Formation. (272 km above the surface, less than 5 km across.)

NASA/JPL/University of Arizona


2018 August 1 The Iris Nebula in a Field of Dust Image Credit…

2018 August 1

The Iris Nebula in a Field of Dust
Image Credit & Copyright: Franco Sgueglia & Francesco Sferlazza

Explanation: What blue flower grows in this field of dark interstellar dust? The Iris Nebula. The striking blue color of the Iris Nebula is created by light from the bright star SAO 19158 reflecting off of a dense patch of normally dark dust. Not only is the star itself mostly blue, but blue light from the star is preferentially reflected by the dust – the same affect that makes Earth’s sky blue. The brown tint of the pervasive dust comes partly from photoluminescence – dust converting ultraviolet radiation to red light. Cataloged as NGC 7023, the Iris Nebula is studied frequently because of the unusual prevalence there of Polycyclic Aromatic Hydrocarbons (PAHs), complex molecules that are also released on Earth during the incomplete combustion of wood fires. The bright blue portion of the Iris Nebula spans about six light years. The Iris Nebula, pictured here, lies about 1300 light years distant and can be found with a small telescope toward the constellation of Cepheus.

∞ Source: apod.nasa.gov/apod/ap180801.html


A novel 3D technique to study the kinematics of lensed galaxies

This schematic view shows lensed images in the top row and the source plane in the bottom row. Lensed data are shown for three representative velocity channels of the data cube; the respective grid on the image plane is regular. For each velocity channel, the position of a pixel in the image plane corresponds to a position on the source plane (lower panel), determined by the lens equation. The points form the vertices of a triangular adaptive grid on the source plane. The source grid automatically adapts with the lensing magnification, so that there is a high pixel density in the high-magnification regions close to the caustics. © MPA

Gravitational lensing offers the possibility to study faint, far-away galaxies. MPA researchers have now developed the first three dimensional lens modelling method, which allows not only the reconstruction of the mass distribution of the foreground galaxy but also the kinematics of the background galaxy. Consequently, the matter content can now be studied also in young galaxies. 

In the standard model of cosmology, galaxies form as the baryonic gas cools at the centre of dark matter halos. They subsequently grow through accretion and mergers, leading to the hierarchical build-up of galaxy mass. While this general picture is well known, there are numerous physical mechanisms determining the relative contribution of baryons and dark matter within a galaxy and several open questions remain: What are the most important physical mechanisms that lead to the variety of galaxies we observe today? How do these mechanisms influence the matter content within galaxies? The answer to these questions is one of the significant challenges of modern astrophysics.

The study of galaxy kinematics has played a key role in this context. For example, in the local universe, the flatness of observed rotation curves is a well-established fact. The outer parts of the observed rotation curves cannot be explained by the mass predicted from the observed stellar and gas distribution and this discrepancy has been interpreted as evidence for the presence of a “dark matter” halo. Within high redshift galaxies, however, the relative content of baryons and dark matter is poorly known and also its evolution with cosmic time is not well understood. Neither current numerical simulations nor observational studies were able to produce consistent results on the fraction of dark matter within young galaxies.


The diverging results on the kinematics of high-redshift galaxies – and in consequence on their matter content – can be ascribed to the different methods used to overcome the observational limitations. The study of kinematics is mainly hampered by two factors: low spatial resolution and low signal-to-noise ratio.

These observational limitations can be successfully overcome by targeting galaxies for which the line of sight lies very close to a foreground galaxy. The gravitational field of the foreground galaxy then deflects the light from the distant background galaxy, producing distorted, magnified, and even multiple images of the background object. This effect is known as strong gravitational lensing and it offers the opportunity to study the background galaxies at high physical resolution and with good signal-to-noise. Furthermore, the magnifying power of gravitational lensing opens the possibility to study faint galaxies with low stellar masses, which are not easily accessible by surveys targeting unlensed galaxies.

The gravitational lensing group at MPA developed the first three dimensional lens modelling method (see Figure 1). This can be applied to 3D (IFU or radio) data, characterized by two spatial dimensions and one spectral dimension (velocity, frequency or wavelength), to simultaneously reconstruct both the mass distribution of the foreground galaxy and the kinematics of the background galaxy (see Figure 2).

For different mock background galaxies, these plots show the velocity fields (upper panels) and rotation curves (bottom panels). The velocity field is colour coded (see bar on the side) with red areas moving away from the observer and blue areas moving towards the observer. The original rotation curves are shown in blue and the best fit kinematic model is shown in red. The orange band shows the possible errors from uncertainties of the parameters that defined the rotation curves.  The mock data M1-M3 have input rotation curves described by functional forms, while for M4-M6 the rotation curves were taken from real galaxies. The rotation curves of M1 and M4 are typical of dwarf galaxies, the rotation curves of M2 and M5 are prototypes of spirals, while those of M3 and M6 are typical of massive spirals with a prominent bulge.© MPA

Our method represents a significant improvement over those used until now, since it does not require the use of high-resolution imaging data for the derivation of the lens parameters, as these are derived from the same 3D data used for the kinematics of the background galaxy. Moreover, the latter is not obtained by fitting on the source plane, but directly the lensed data. This is achieved in a hierarchical Bayesian fashion, where the kinematics on the source plane is essentially a hyper-parameter of the model (i.e. a parameter defining the prior). We are thus able to study the possible degeneracies between the lens and kinematic parameters and estimate the uncertainties consistently.

With our technique we are able to recover both the lens and the kinematics parameters with great accuracy under different observational conditions. Furthermore, we have successfully tested the capability of this new method in recovering a variety of rotation curves with shapes which are prototypes of different morphological galaxy types, from dwarf to massive spiral galaxies (see Figure 3).


Francesca Rizzo
PhD student
Phone: 2019
Email: frizzo@mpa-garching.mpg.de
Room: 107

Simona Vegetti
Scientific Staff
Phone: 2285
Email: svegetti@mpa-garching.mpg.de
Room: 105

Original Publication

1. Rizzo F., Vegetti S., Fraternali F., Di Teodoro E.

A novel 3D technique to study the kinematics of lensed galaxies

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Swinside Stone Circle, Cumbria, 31.7.18.

Swinside Stone Circle, Cumbria, 31.7.18.

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The Pollington Skeleton, Roman Burial and Stone Sarcophagus,…

The Pollington Skeleton, Roman Burial and Stone Sarcophagus, Doncaster Museum and Gallery, Yorkshire, 29.7.18.

This stone sarcophagus was discovered in a stone quarry in Pollington, Yorkshire. It is the skeleton of a high status female of around fifty years of age. Very unusually the burial is influenced by Egyptian funerary rituals. The inner lining of the stone coffin is of a limestone plaster. The burial was conducted in the 4th century CE and this is unusual in that most Romans were commonly cremated at this time.

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The Rossington Bridge Roman Dagger, Doncaster Museum and…

The Rossington Bridge Roman Dagger, Doncaster Museum and Gallery, Yorkshire, 29.7.18.

A Roman soldier lost the dagger in the waters and marshland near Rossington Bridge Roman fort. The iron dagger had a bone handle which consisted of several parts, each separated by the iron washers on the existing tang which can still be seen. The dagger also had a wooden and leather sheath and part of the original wood still exists on the blade.

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Ocean acidification to hit levels not seen in 14 million years

New research led by Cardiff University has shown that under a ‘business-as-usual’ scenario of carbon dioxide (CO2) emissions, ocean acidification is likely to hit unprecedented levels.

Ocean acidification to hit levels not seen in 14 million years
Credit: Cardiff University

Ocean acidification occurs when CO2 from the atmosphere is absorbed by seawater, resulting in more acidic water with a lower pH.

Around a third of the CO2 released by burning coal, oil and gas gets dissolved into the oceans. Since the beginning of the industrial era, the ocean has absorbed around 525 billion tons of CO2, equivalent to around 22 million tons per day.

The rapid influx of CO2 in to the oceans is severely threatening marine life, with the shells of some animals already dissolving in the more acidic seawater.

In their new study, published in the journal Earth and Planetary Science Letters, the researchers set out to reconstruct levels of ocean acidity and atmospheric CO2 levels over the past 22 million years.

They did so by studying the fossils of tiny marine creatures that once lived near the ocean surface, specifically using the chemistry of their shells to monitor the acidity of the seawater in which the creatures lived.

Based on this information, the researchers were able to put their new records of pH and CO2 levels in context of the range of future carbon emission scenarios that are recognised by the Intergovernmental Panel on Climate Change (IPCC).

Under a ‘business-as-usual’ future scenario where we continue to emit CO2 at the same rate as we do today, atmospheric CO2 would be near 930 parts per million in the year 2100, compared to around 400 parts per million today.

Similarly, the pH of the oceans would be less than 7.8 in 2100 compared to a pH of around 8.1 today. This is very significant as the pH scale is logarithmic, meaning a drop of just 0.1 pH units represents a 25% increase in acidity.

These levels of atmospheric CO2 and ocean acidity have not been since the Middle Miocene Climatic Optimum period around 14 million years ago, when global temperatures were around 3°C warmer than today as a result of the Earth’s natural geological cycle.

Lead author of the study Dr. Sindia Sosdian, from Cardiff University’s School of Earth and Ocean Sciences, said: “Our new geological record of ocean acidification shows us that on our current ‘business as usual’ emission trajectory, oceanic conditions will be unlike marine ecosystems have experienced for the last 14 million years.”

Professor Carrie Lear, co-author of the study, added: “The current pH is already probably lower than any time in the last 2 million years. Understanding exactly what this means for marine ecosystems requires long-term laboratory and field studies as well as additional observations from the fossil record.”

Author: Julia Short | Source: Cardiff University [July 27, 2018]




Uncatalogued ‘dinosaur’ fossil found to belong to iconic extinct Japanese...

In the spring of 2017, Dr Yuri Kimura, from the Department of Geology and Paleontology at the National Museum of Nature and Science, Tsukuba, found a large bone inside an old wooden box in the geological collection room of the University of Tsukuba, Japan. Based on the overall features, she knew the thigh bone (or femur) belonged to an extinct marine mammal, a member of the order Desmostylia, thought to be related to hippo-like rhinoceroses, or sea cows.

Uncatalogued 'dinosaur' fossil found to belong to iconic extinct Japanese mammal, Paleoparadoxia
This is probably what Paleoparadoxia looked like during its lifetime, about 15.9 million years ago
[Credit: Kumiko Matsui et al./Royal Society/]

Dr Kimura teamed up with Dr Kumiko Matsui, one of the few Desmostylia experts, and her colleagues, to reveal the scientific significance of the fossil. As revealed in the journal, Royal Society Open Science, they identified the bone as belonging to the genus Paleoparadoxia.

They were large, four-limbed, marine mammals that lived in the North Pacific rim, from Japan to the western coast of the USA and Mexico, 23-10 million years ago. With the help of an old note and local knowledge they also discovered that it was unearthed during dam construction in the town of Tsuchiyu Onsen, near the city of Fukushima.

The age of the bone was estimated as 16 million years old or younger. The bone shows well-preserved muscle scars on the surface, making it useful for future studies of the locomotion of the hind limb.

Uncatalogued 'dinosaur' fossil found to belong to iconic extinct Japanese mammal, Paleoparadoxia
The box where researchers found the mysterious Paleoparadoxia fossil
[Credit: Yuri Kimura]

By interviewing the local inhabitants, the scientists found two people who knew about the fossil and/or the name on the old label. The fossil was known to be a ‘dinosaur’ bone by locals and was displayed in the village hall until an unknown university teacher took it.

A devastating fire destroyed most of the city and the village hall that year. The discrepancy between the date on the old label and the verbal accounts make it impossible to identify the exact location of the fossil. The scientists were, however, able to identify two equally possible locations that are only 350m apart.

As Dr Kimura explains, “Museum collections are passed down from generation to generation, hopefully for thousands of years or more. For that, specimen information must be tagged with museum materials. We are happy that specimen information was extracted, even after a long hiatus owing to the hand-written note kept with the fossil, as well as the kind help of local people. A big discovery often results from a series of fortunate events. Although this fossil was unfortunately forgotten for decades in a cabinet, luck was on its side this time. We believe that this specimen is a good lesson not only for vertebrate palaeontologists but also for all museum curators and researchers.”

Source: University of Tsukuba [July 27, 2018]




Roman and Bronze Age artefacts discovered on Bristol university construction site

Roman jewellery, coins and Bronze Age pottery have been discovered on a university’s construction site.

Roman and Bronze Age artefacts discovered on Bristol university construction site
Two of the coins discovered [Credit: UWE Bristol]

The finds were unearthed on the Hillside Gardens building site in Frenchay – the University of the West of England’s (UWE) new sports centre which is due to open in the autumn.

The items found during excavation work for the facility included Bronze Age pottery, a Roman bracelet, coins and a necklace bead from the Iron Age.

Archaeologists from Cotswolds Archaeology made the discovery earlier in 2018 and also uncovered a Roman settlement nearby – apparently a farmstead – which included a circular ditch that experts believe was a roundhouse.

Shards of pottery were also found there, believed to date back to a time between the late Bronze and early Iron ages. Pottery from between the first and fourth centuries AD was also discovered.

Two copper-alloy coins from the site are of particular interest to archaeologists. Tom Brindle, who is Post-Excavation Manager at Cotswold Archaeology said: “Many rural Roman sites in Britain do not produce coins, however Hillside Gardens falls within the part of the country where coins at rural sites are much more common. One of the coins is of Emperor Crispus, and was struck at a mint in London between AD 318 and 324.

“The occupants may have been familiar with their use for making purchases at markets but barter and the fulfilment of social obligations may well have served as methods of exchange alongside coinage too.”

Peter Fleming, who is Professor of History at UWE Bristol, said: “This is a very rare find. Bristol is widely believed to have originated long after the date to which these finds have been allocated – the Romans seem not to have realised how much scope there was on the site where Bristol later grew up, and there does not seem to have been a major villa site around here. So, the farm to which these finds belonged would have been a smaller occupancy than a villa.”

Source: Bristol Live [July 28, 2018]




Six 2000-year-old Greek statues discovered in southwestern Turkey

Six statues dating back 2,000 years were discovered Saturday in the ruins of the ancient Greek city of Magnesia, located in southwestern Aydın province’s Germencik district.

Six 2000-year-old Greek statues discovered in southwestern Turkey
Credit: AA

Prof. Orhan Bingöl, who has been overseeing the excavations in the site since 1984, said four female and one male statues were unearthed in the ruins of a temple to Artemis, adding that one of the statues’ gender was unknown.

Six 2000-year-old Greek statues discovered in southwestern Turkey
Credit: AA

Bingöl said all statues were found in the same area and were in good condition of preservation, placed face-down next to each other.

Six 2000-year-old Greek statues discovered in southwestern Turkey
Credit: AA

“We know that, along with the ones being displayed in Istanbul, Izmir and Aydın, there have been nearly 50 statues unearthed from Magnesia ruins. This discovery will not be the end of it and clearly shows we can find more statues in this particular area,” Bingöl said.

Six 2000-year-old Greek statues discovered in southwestern Turkey
Credit: AA

The first excavations in Magnesia were conducted between 1891 and 1893 by a German archaeological team led by Carl Humann. The work lasted 21 months and partially revealed the theater, the Artemis temple, the agora, the Zeus temple and the prytaneion.

Six 2000-year-old Greek statues discovered in southwestern Turkey
Credit: AA

Excavations were resumed at the site, after an interval of almost 100 years, in 1984, by Bingöl.

Source: Daily Sabah [July 28, 2018]




US judge orders return of ancient limestone relief to Iran

A New York Supreme Court judge on Monday ordered a Persian bas-relief dating to approximately 500 B.C. to be returned to Iran, the country from which authorities say it was stolen more than 80 years ago.

US judge orders return of ancient limestone relief to Iran
A 1933 photograph of an excavation of the ruins of Persepolis in Iran. The bas-relief of a soldier from these ruins,
which was seized at a Manhattan art fair last year, was ordered to be returned to Iran on Monday
[Credit: Oriental Institute of the University of Chicago]

The bas-relief, which depicts a Persian guard, was seized in October by investigators for the Manhattan district attorney’s office from the Park Avenue Armory, where it was being offered for sale at an art fair.

As part of the ensuing negotiations, the two London-based owners of the relief agreed to surrender the item, valued at $1.2 million. Investigators say the item was reported stolen from Persepolis in 1936, and then was stolen a second time, in 2011, from the Montreal Museum of Fine Arts, to which it had been donated decades earlier.

In court papers, the district attorney’s office argued that no one can be a good-faith purchaser of a stolen work.

Rupert Wace, a well-known dealer in antiquities in London, and his partner, Sam Fogg, have said they acquired the work legally from the Montreal museum’s insurance company. But after investigators laid out a lengthy and detailed timeline they said showed that the item was in fact stolen, the men signed court papers agreeing to the surrender.

At the time of the seizure, Mr. Wace had said in an email, “This work of art has been well known to scholars and has a history that spans almost 70 years.” He had added that he and Mr. Fogg were “simply flabbergasted at what has occurred.”

US judge orders return of ancient limestone relief to Iran
This fragment from a bust of Alexander the Great, dated as early as 300 B.C.,
was excavated from the site of the Roman Forum in the early 1900s and later
stolen from the Forense Museum in Rome sometime before 1959
[Credit: Manhattan District Attorney’s Office]

The bas-relief is an eight-inch-square piece of carved limestone that was part of a long line of soldiers depicted on a balustrade at the central building on the Persepolis site. It dates to the Achaemenid dynasty — or the First Persian Empire — and experts said it was made sometime between 510 and 330 B.C., when Persepolis was sacked by Alexander the Great.

The district attorney’s office has made investigating looted antiquities a priority in recent years and even created a new squad devoted to that mission last year. Aided by forensic researchers and legal specialists, the office has pieced together the histories of dozens of illicit items that arrived in New York for sale.

In fact, even as the court was ruling on the return of the Persian piece, the office was filing paperwork in court in a separate case in which it asks for the return of a second antiquity it says was looted — a head of Alexander the Great excavated from the site of the Roman Forum in the early 1900s. Prosecutors said the item was stolen from the Forense Museum in Rome sometime before 1959. After a serpentine journey across several European borders, the object made its way to New York. in February, it was seized from the Alan Safani Gallery in Manhattan, which had purchased it last year from a London gallery.

Mr. Safani’s lawyer, David Schoen, said his client had bought the piece, which has been advertised by reputable dealers, in good faith. He noted that investigators in their filing had found that Mr. Safani had acted commendably in attempting to research the history of work and had engaged in “reasonable inquiry” as to the provenance of the bust.

That bust dates to as early as 300 B.C. and investigators said in their filing that it lacks the kind of documents that normally accompany ancient artifacts when they leave Italy. It turned up at auction at Sotheby’s in 1974, and was sold there again in 2011.“Experience tells us that this is exactly what the black market in looted antiquities always looks like,” prosecutors said in their filing. “A disappearance from a source country and then a miraculous reappearance many years later in a market country with no paperwork, followed by a questionable sale designed to create an ownership history.”

Source: New York Times [July 28, 2018]




Mexican experts find seeds, cloth around mummified child

A CAT scan of a rolled-up straw mat found in a northern Mexico cave has revealed the mummified remains of a 1 ½ year-old boy.

Mexican experts find seeds, cloth around mummified child
Credit: Mauricio Marat/INAH

The country’s National Institute of Anthropology and History says that researchers trying to determine the age of the funeral bundle.

Mexican experts find seeds, cloth around mummified child
Credit: Mauricio Marat/INAH

But the institute said Sunday that organic materials in the cave in Tamaulipas state have been dated between 1,600 B.C. and 1,200 A.D.

Mexican experts find seeds, cloth around mummified child
Credit: Mauricio Marat/INAH

The child’s body bore a piece of cloth, and bone and shell ornaments. But perhaps just as interesting was a woven basket left near the body, apparently as an offering.

Mexican experts find seeds, cloth around mummified child
Credit: Mauricio Marat/INAH

It contained 756 acorns and 52 ears of primitive corn, as well as squash stems.

The find may shed more light on the transition to sedentary agricultural communities in the region.

Source: The Associated Press [July 30, 2018]




Pair of colliding stars spill radioactive molecules into space

When two Sun-like stars collide, the result can be a spectacular explosion and the formation of an entirely new star. One such event was seen from Earth in 1670. It appeared to observers as a bright, red “new star.” Though initially visible with the naked eye, this burst of cosmic light quickly faded and now requires powerful telescopes to see the remains of this merger: a dim central star surrounded by a halo of glowing material flowing away from it.

Pair of colliding stars spill radioactive molecules into space
Artist impression of the collision of two stars, like the ones that formed CK Vul. The inset illustrates the inner structure
 of one red giant before the merger. A thin layer of 26-aluminum (brown) surrounds a helium core. An extended
convective envelope (not to scale), which forms the outermost layer of the star, can mix material from inside
 the star to the surface, but it never reaches deep enough to dredge 26-aluminum up to the surface. Only
a collision with another star can disperse 26-aluminum [Credit: NRAO/AUI/NSF; S. Dagnello]

Approximately 348 years after this event, an international team of astronomers using the Atacama Large Millimeter/submillimeter Array (ALMA) and the NOEMA (Northern Extended Millimeter Array) radio telescopes studied the remains of this explosive stellar merger — known as CK Vulpeculae (CK Vul) — and discovered the clear and convincing signature of a radioactive version of aluminum (26Al, an atom with 13 protons and 13 neutron) bound with atoms of fluorine, forming 26-aluminum monofluoride (26AlF).

This is the first molecule bearing an unstable radioisotope definitively detected outside of our solar system. Unstable isotopes have an excess of nuclear energy and eventually decay into a stable, less-radioactive form. In this case, the 26-aluminum (26Al) decays to 26-magnesium (26Mg).

“The first solid detection of this kind of radioactive molecule is an important milestone in our exploration of the cool molecular universe,” said Tomasz Kamiński, an astronomer with the Harvard-Smithsonian Center for Astrophysics in Cambridge, Mass., and lead author on a paper appearing in Nature Astronomy.

The researchers detected the unique spectral signature of these molecules in the debris surrounding CK Vul, which is approximately 2,000 light-years from Earth. As these molecules spin and tumble through space, they emit a distinctive fingerprint of millimeter-wavelength light, a process known as “rotational transition.” Astronomers consider this the “gold standard” for molecular detections.

These characteristic molecular fingerprints are usually taken from laboratory experiments and then used to identify molecules in space. In the case of 26AlF, this method is not applicable because 26-aluminum is not present on Earth. Laboratory astrophysicists from the University of Kassel/Germany therefore used the fingerprint data of stable and abundant 27AlF molecules to derive accurate data for the rare 26AlF molecule. “This method of extrapolation is based on the so-called Dunham approach,” explained Alexander Breier from the Kassel team. “It allows researchers to precisely calculate the rotational transitions of 26AlF with an accuracy far beyond the needs of astronomical observers.”

Pair of colliding stars spill radioactive molecules into space
Composite image of CK Vul, the remains of a double-star collision. This impact launched radioactive molecules into
 space, as seen in the orange double-lobe structure at the center. This is an ALMA image of 27-aluminum monofluoride,
 but the rare isotopic version of AlF resides in the same region. The red, diffuse image is an ALMA image of the
more extended dust in the region. The blue is optical hydrogen emission as seen by the Gemini observatory
[Credit: ALMA (ESO/NAOJ/NRAO), T. Kami?ski & M. Hajduk; Gemini, NOAO/AURA/NSF;
NRAO/AUI/NSF, B. Saxton]

The observation of this particular isotopologue provides fresh insights into the merger process that created CK Vul. It also demonstrates that the deep, dense inner layers of a star, where heavy elements and radioactive isotopes are forged, can be churned up and cast into space by stellar collisions. “We are observing the guts of a star torn apart three centuries ago by a collision,” observed Kamiński. “How cool is that?”

The astronomers also determined that the two stars that merged were relatively low-mass, with one being a red giant star with a mass somewhere between 0.8 and 2.5 times that of our Sun.

“This first direct observation of this isotope in a stellar-like object is also important in the broader context of galactic chemical evolution,” noted Kamiński. “This is the first time an active producer of the radioactive nuclide 26Al has been directly observationally identified.”

It has been known for decades that there is about three entire Suns’ worth of 26Al spread across the Milky Way. But these observations, made at gamma-ray wavelengths, could only identify that the signal was there; they couldn’t pinpoint individual sources and it was unclear how the isotopes got there.

With current estimates on the mass of 26Al in CK Vul (about a quarter the mass of Pluto) and the rare occurrence of mergers such as this, it seems rather unlikely that mergers are solely responsible for this galactic radioactive material, the astronomers conclude.

However, ALMA and NOEMA can only detect the amount of 26Al bound with fluorine. The actual mass of 26Al in CK Vul (in atomic form) may be much greater. It is also possible that other merger remnants may have far greater amounts. Astronomers may also have underestimated the current merger rates in the Milky Way. “So this is not a closed issue and the role of mergers may be non-negligible,” speculated Kamiński.

Source: National Radio Astronomy Observatory [July 30, 2018]




Plate tectonics not needed to sustain life

There may be more habitable planets in the universe than we previously thought, according to Penn State geoscientists, who suggest that plate tectonics — long assumed to be a requirement for suitable conditions for life — are in fact not necessary.

Plate tectonics not needed to sustain life
The artist’s concept depicts Kepler-69c, a super-Earth-size planet in the habitable zone of a star like our sun,
located about 2,700 light-years from Earth in the constellation Cygnus [Credit: NASA]

When searching for habitable planets or life on other planets, scientists look for biosignatures of atmospheric carbon dioxide. On Earth, atmospheric carbon dioxide increases surface heat through the greenhouse effect. Carbon also cycles to the subsurface and back to the atmosphere through natural processes.

“Volcanism releases gases into the atmosphere, and then through weathering, carbon dioxide is pulled from the atmosphere and sequestered into surface rocks and sediment,” said Bradford Foley, assistant professor of geosciences. “Balancing those two processes keeps carbon dioxide at a certain level in the atmosphere, which is really important for whether the climate stays temperate and suitable for life.”

Most of Earth’s volcanoes are found at the border of tectonic plates, which is one reason scientists believed they were necessary for life. Subduction, in which one plate is pushed deeper into the subsurface by a colliding plate, can also aid in carbon cycling by pushing carbon into the mantle.

Planets without tectonic plates are known as stagnant lid planets. On these planets, the crust is one giant, spherical plate floating on mantle, rather than separate pieces. These are thought to be more widespread than planets with plate tectonics. In fact, Earth is the only planet with confirmed tectonic plates.

Foley and Andrew Smye, assistant professor of geosciences, created a computer model of the lifecycle of a planet. They looked at how much heat its climate could retain based on its initial heat budget, or the amount of heat and heat-producing elements present when a planet forms. Some elements produce heat when they decay. On Earth, decaying uranium produces thorium and heat, and decaying thorium produces potassium and heat.

After running hundreds of simulations to vary a planet’s size and chemical composition, the researchers found that stagnant lid planets can sustain conditions for liquid water for billions of years. At the highest extreme, they could sustain life for up to 4 billion years, roughly Earth’s life span to date.

“You still have volcanism on stagnant lid planets, but it’s much shorter lived than on planets with plate tectonics because there isn’t as much cycling,” said Smye. “Volcanoes result in a succession of lava flows, which are buried like layers of a cake over time. Rocks and sediment heat up more the deeper they are buried.”

The researchers found that at high enough heat and pressure, carbon dioxide gas can escape from rocks and make its way to the surface, a process known as degassing. On Earth, Smye said, the same process occurs with water in subduction fault zones.

This degassing process increases based on what types and quantities of heat-producing elements are present in a planet up to a certain point, said Foley.

“There’s a sweet spot range where a planet is releasing enough carbon dioxide to keep the planet from freezing over, but not so much that the weathering can’t pull carbon dioxide out of the atmosphere and keep the climate temperate,” he said.

According to the researchers’ model, the presence and amount of heat-producing elements were far better indicators for a planet’s potential to sustain life.

“One interesting take-home point of this study is that the initial composition or size of a planet is important in setting the trajectory for habitability,” said Smye. “The future fate of a planet is set from the outset of its birth.”

The researchers published their findings in Astrobiology.

Author: Liam Jackson | Source: Pennsylvania State University [July 30, 2018]




Ever-increasing CO2 levels could take us back to the tropical climate of Paleogene period

A new study led by scientists at the University of Bristol has warned that unless we mitigate current levels of carbon dioxide emissions, Western Europe and New Zealand could revert to the hot tropical climate of the early Paleogene period – 56-48 million years ago.

Ever-increasing CO2 levels could take us back to the tropical climate of Paleogene period
Typical vegetation from the Paleogene period [Credit: University of Bristol]

As seen from the ongoing heat wave, the knock-on effects of such extreme warmth include arid land and fires as well as impacts on health and infrastructure.

The early Paleogene is a period of great interest to climate change scientists as carbon dioxide levels (around 1,000 ppmv) are similar to those predicted for the end of this century.

Dr David Naafs from the University of Bristol’s School of Earth Sciences, led the research published in the journal, Nature Geoscience. He said: “We know that the early Paleogene was characterised by a greenhouse climate with elevated carbon dioxide levels.

“Most of the existing estimates of temperatures from this period are from the ocean, not the land – what this study attempts to answer is exactly how warm it got on land during this period.”

Scientists used molecular fossils of microorganisms in ancient peat (lignite) to provide estimates of land temperature 50 million-years ago. This demonstrated that annual land temperatures in Western Europe as well as New Zealand were actually higher than previously thought – between 23 and 29 °C – this is currently 10 to 15 °C higher than current average temperatures in these areas.

These results suggest that temperatures similar to those of the current heat wave that is influencing western Europe and other regions would become the new norm by the end of this century if CO2 levels in the atmosphere continue to increase.

Professor Rich Pancost, Co-author and Director of the University of Bristol Cabot Institute, added: “Our work adds to the evidence for a very hot climate under potential end-of-century carbon dioxide levels. “Importantly, we also study how the Earth system responded to that warmth. For example, this and other hot time periods were associated with evidence for arid conditions and extreme rainfall events.”

The research team will now turn their attentions to geographical areas in lower-latitudes to see how hot land temperatures were there.

Dr Naafs said: “Did the tropics, for example, become ecological dead zones because temperatures in excess of 40 °C were too high for most form of life to survive?

“Some climate models suggest this, but we currently lack critical data.

“Our results hint at the possibility that the tropics, like the mid-latitudes, were hotter than present, but more work is needed to quantify temperatures from these regions.”

Source: University of Bristol [July 30, 2018]




Researchers reveal hidden rules of genetics for how life on Earth began

All living things use the genetic code to “translate” DNA-based genetic information into proteins, which are the main working molecules in cells. Precisely how the complex process of translation arose in the earliest stages of life on Earth more than four billion years ago has long been mysterious, but two theoretical biologists have now made a significant advance in resolving this mystery.

Researchers reveal hidden rules of genetics for how life on Earth began
In the beginning, somehow basic genetic building blocks got translated into proteins to lead
to complex life as we know it [Credit: Christ-claude Mowandza-ndinga]

Charles Carter, PhD, professor of biochemistry and biophysics at the UNC School of Medicine, and Peter Wills, PhD, an associate professor of biochemistry at the University of Auckland, used advanced statistical methods to analyze how modern translational molecules fit together to perform their job – linking short sequences of genetic information to the protein building blocks they encode.

The scientists’ analysis, published in Nucleic Acids Research, reveals previously hidden rules by which key translational molecules interact today. The research suggests how the much-simpler ancestors of these molecules began to work together at the dawn of life.

“I think we have clarified the underlying rules and the evolutionary history of genetic coding,” Carter said. “This had been unresolved for 60 years.”

Wills added, “The pairs of molecular patterns we have identified may be the first that nature ever used to transfer information from one form to another in living organisms.”

The discoveries center on a cloverleaf-shaped molecule called transfer RNA (tRNA), a key player in translation. A tRNA is designed to carry a simple protein building-block, known as an amino acid, onto the assembly line of protein production within tiny molecular factories called ribosomes. When a copy or “transcript” of a gene called a messenger RNA (mRNA) emerges from the cell nucleus and enters a ribosome, it is bound to tRNAs carrying their amino acid cargoes.

The mRNA is essentially a string of genetic “letters” spelling out protein-making instructions, and each tRNA recognizes a specific three-letter sequence on the mRNA. This sequence is called a “codon.” As the tRNA binds to the codon, the ribosome links its amino acid to the amino acid that came before it, elongating the growing peptide. When completed, the chain of amino acids is released as a newly born protein.

Proteins in humans and most other life forms are made from 20 different amino acids. Thus there are 20 distinct types of tRNA molecules, each capable of linking to one particular amino acid. Partnering with these 20 tRNAs are 20 matching helper enzymes known as synthetases (aminoacyl-tRNA synthetases), whose job it is to load their partner tRNAs with the correct amino acid.

“You can think of these 20 synthetases and 20 tRNAs collectively as a molecular computer that evolution has designed to make gene-to-protein translation happen,” Carter said.

Biologists have long been intrigued by this molecular computer and the puzzle of how it originated billions of years ago. In recent years, Carter and Wills have made this puzzle their principal research focus. They have shown, for example, how the 20 synthetases, which exist in two structurally distinct classes of 10 synthetases, likely arose from just two simpler, ancestral enzymes.

A similar class division exists for amino acids, and Carter and Wills have argued that the same class division must apply to tRNAs. In other words, they propose that at the dawn of life on Earth, organisms contained just two types of tRNA, which would have worked with two types of synthetases to perform gene-to-protein translation using just two different kinds of amino acids.

The idea is that over the course of eons this system became ever more specific, as each of the original tRNAs, synthetases, and amino acids was augmented or refined by new variants until there were distinct classes of 10 in place of each of the two original tRNAs, synthetases, and amino acids.

In their most recent study, Carter and Wills examined modern tRNAs for evidence of this ancient duality. To do so they analyzed the upper part of the tRNA molecule, known as the acceptor stem, where partner synthetases bind. Their analysis showed that just three RNA bases, or letters, at the top of the acceptor stem carry an otherwise hidden code specifying rules that divide tRNAs into two classes – corresponding exactly to the two classes of synthetases. “It is simply the combinations of these three bases that determine which class of synthetase binds to each tRNA,” Carter said.

The study serendipitously found evidence for another proposal about tRNAs. Each modern tRNA has at its lower end an “anticodon” that it uses to recognize and stick to a complementary codon on an mRNA. The anticodon is relatively distant from the synthetase binding site, but scientists since the early 1990s have speculated that tRNAs were once much smaller, combining the anticodon and synthetase binding regions in one. Wills and Carter’s analysis shows that the rules associated with one of the three class-determining bases – base number 2 in the overall tRNA molecule – effectively imply a trace of the anticodon in an ancient, truncated version of tRNA.

“This is a completely unexpected confirmation of a hypothesis that has been around for almost 30 years,” Carter said.

These findings strengthen the argument that the original translational system had just two primitive tRNAs, corresponding to two synthetases and two amino acid types. As this system evolved to recognize and incorporate new amino acids, new combinations of tRNA bases in the synthetase binding region would have emerged to keep up with the increasing complexity – but in a way that left detectable traces of the original arrangement.

“These three class-defining bases in contemporary tRNAs are like a medieval manuscript whose original texts have been rubbed out and replaced by newer texts,” Carter said.

The findings narrow the possibilities for the origins of genetic coding. Moreover, they narrow the realm of future experiments scientists could conduct to reconstruct early versions of the translational system in the laboratory – and perhaps even make this simple system evolve into more complex, modern forms of the same translation system. This would further show how life evolved from the simplest of molecules into cells and complex organisms.

Source: University of North Carolina Health Care [July 30, 2018]




Do bacteria ever go extinct? New research says yes, bigtime

Bacteria go extinct at substantial rates, although appear to avoid the mass extinctions that have hit larger forms of life on Earth, according to new research from the University of British Columbia (UBC), Caltech, and Lawrence Berkeley National Laboratory. The finding contradicts widely held scientific thinking that microbe taxa, because of their very large populations, rarely die off.

Do bacteria ever go extinct? New research says yes, bigtime
Despite their ancient history and ubiquity, the diversity of bacteria remains one of the most cryptic
chapters of the history of life [Credit: Stilianos Louca, University of British Columbia]

The study, published in Nature Ecology and Evolution, used massive DNA sequencing and big data analysis to create the first evolutionary tree encompassing a large fraction of Earth’s bacteria over the past billion years.

“Bacteria rarely fossilize, so we know very little about how the microbial landscape has evolved over time,” says Stilianos Louca, a researcher with UBC’s Biodiversity Research Centre who led the study. “Sequencing and math helped us fill in the bacterial family tree, map how they’ve diversified over time, and uncover their extinctions.”

Louca and colleagues estimate between 1.4 and 1.9 million bacterial lineages exist on Earth today. They were also able to determine how that number has changed over the last billion years — with 45,000 to 95,000 extinctions in the last million years alone.

“While modern bacterial diversity is undoubtedly high, it’s only a tiny snapshot of the diversity that evolution has generated over Earth’s history,” says Louca.

Do bacteria ever go extinct? New research says yes, bigtime
Stromatolites are some of the very few indicators of ancient microbial life
[Credit: Woodward Fischer, California Institute of Technology]

Despite the frequent, steady extinction of individual species, the work shows that — overall — bacteria have been diversifying exponentially without interruption. And they’ve avoided the abrupt, planet-wide mass extinctions that have periodically occurred among plants and animals. Louca suspects that competition between bacterial species drive the high rate of microbial extinctions, leaving them less prone to sudden mass, multi-species extinctions.

Past speciation and extinction events leave a complex trace in phylogenies — mathematical structures that encode the evolutionary relatedness between existing bacterial species.

“This study wouldn’t have been possible 10 years ago,” says Michael Doebeli, UBC mathematician and zoologist, and senior author on the paper. “Today’s availability of massive sequencing data and powerful computational resources allowed us to perform the complex mathematical analysis.”

Next, Louca and his colleagues want to determine how the physiological properties of bacteria evolve over time, and whether their ecological diversity has also been increasing similarly to their taxonomic diversity. If this is true, it would mean that even ancient and relatively simple organisms such as bacteria still have the potential to discover novel ways to survive.

Source: University of British Columbia [July 30, 2018]




Carbon ‘leak’ may have warmed the planet for 11,000 years, encouraging human...

The oceans are the planet’s most important depository for atmospheric carbon dioxide on time scales of decades to millenia. But the process of locking away greenhouse gas is weakened by activity of the Southern Ocean, so an increase in its activity could explain the mysterious warmth of the past 11,000 years, an international team of researchers reports.

Carbon 'leak' may have warmed the planet for 11,000 years, encouraging human civilization
Diatoms like this one, microscopic plants with silica shells, trapped trace amounts of nitrogen in their shells as they grew.
 Researchers in the Sigman Lab at Princeton University were able to extract that minuscule amount of nitrogen
from countless fossil diatoms and create a model for the activity of the Southern Ocean during the Holocene,
a period that began about 11,000 years ago. This centric diatom, photographed through a microscope,
measures about 70 microns across and lived in the Indian Southern Ocean during the Holocene
[Credit: Anja Studer, Max Planck Institute for Chemistry]

The warmth of that period was stabilized by a gradual rise in global carbon dioxide levels, so understanding the reason for that rise is of great interest, said Daniel Sigman, the Dusenbury Professor of Geological and Geophysical Sciences at Princeton.

Scientists have proposed various hypotheses for that carbon dioxide increase, but its ultimate cause has remained unknown. Now, an international collaboration led by scientists from Princeton and the Max Planck Institute for Chemistry point to an increase in Southern Ocean upwelling. Their research appears in the current issue of the journal Nature Geoscience.

“We think we may have found the answer,” said Sigman. “Increased circulation in the Southern Ocean allowed carbon dioxide to leak into the atmosphere, working to warm the planet.”

Their findings about ocean changes could also have implications for predicting how global warming will affect ocean circulation and how much atmospheric carbon dioxide will rise due to fossil fuel burning.

For years, researchers have known that growth and sinking of phytoplankton pumps carbon dioxide deep into the ocean, a process often referred to as the “biological pump.” The biological pump is driven mostly by the low latitude ocean but is undone closer to the poles, where carbon dioxide is vented back to the atmosphere by the rapid exposure of deep waters to the surface, Sigman said. The worst offender is the Southern Ocean, which surrounds Antarctica. “We often refer to the Southern Ocean as a leak in the biological pump,” Sigman said.

Sigman and his colleagues have found that an increase in the Southern Ocean’s upwelling could be responsible for stabilizing the climate of the Holocene, the period reaching more than 10,000 years before the Industrial Revolution.

Most scientists agree that the Holocene’s warmth was critical to the development of human civilization. The Holocene was an “interglacial period,” one of the rare intervals of warm climate that have occurred over the ice age cycles of the last million years. The retreat of the glaciers opened a more expansive landscape for humans, and the higher concentrations of carbon dioxide in the atmosphere made for more productive agriculture, which allowed people to reduce their hunter-gathering activities and build permanent settlements.

The Holocene differed from other interglacial periods in several key ways, say the researchers. For one, its climate was unusually stable, without the major cooling trend that is typical of the other interglacials. Secondly, the concentration of carbon dioxide in the atmosphere rose about 20 parts per million (ppm), from 260 ppm in the early Holocene to 280 ppm in the late Holocene, whereas carbon dioxide was typically stable or declined over other interglacial periods.

Carbon 'leak' may have warmed the planet for 11,000 years, encouraging human civilization
Researchers in the Sigman Lab at Princeton University extracted trace amounts of nitrogen from fossils to create a
model for the activity of the Southern Ocean during the Holocene, a warm period that began about 11,000 years
ago, during which agriculture and human civilization flourished. The fossils they studied included (from left):
planktonic foraminifer Globigerina bulloides, a centric diatom, and deep-sea coral Desmophyllum dianthus
[Credit: From left: Ralf Schiebel, Max Planck Institute for Chemistry; Anja Studer, Max Planck
Institute for Chemistry; Dann Blackwood, United States Geological Survey]

For comparison, since the beginning of industrialization until now, the carbon dioxide concentration in the atmosphere has increased from 280 to more than 400 ppm as a consequence of burning fossil fuels.

“In this context, the 20 ppm increase observed during the Holocene may seem small,” said Sigman. “However, scientists think that this small but significant rise played a key role in preventing progressive cooling over the Holocene, which may have facilitated the development of complex human civilizations.”

In order to study the potential causes of the Holocene carbon dioxide rise, the researchers investigated three types of fossils from several different areas of the Southern Ocean: diatoms and foraminifers, both shelled microorganisms found in the oceans, and deep-sea corals.

From the nitrogen isotope ratios of the trace organic matter trapped in the mineral walls of these fossils, the scientists were able to reconstruct the evolution of nutrient concentrations in Southern Ocean surface waters over the past 10,000 years.

“The method we used to analyze the fossils is unique and provides a new way to study past changes in ocean conditions,” says Anja Studer, first author of the study, who performed the research while a graduate student working with Sigman’s lab.

The fossil-bound nitrogen isotope measurements indicate that during the Holocene, increasing amounts of water, rich in nutrients and carbon dioxide, welled up from the deep ocean to the surface of the Southern Ocean. While the cause for the increased upwelling is not yet clear, the most likely process appears to be a change in the “Roaring 40s,” a belt of eastward-blowing winds that encircle Antarctica.

Because of the enhanced Southern Ocean upwelling, the biological pump weakened over the Holocene, allowing more carbon dioxide to leak from the deep ocean into the atmosphere and thus possibly explaining the 20 ppm rise in atmospheric carbon dioxide.

“This process is allowing some of that deeply stored carbon dioxide to invade back to the atmosphere,” said Sigman. “We’re essentially punching holes in the membrane of the biological pump.”

The increase in atmospheric carbon dioxide levels over the Holocene worked to counter the tendency for gradual cooling that dominated most previous interglacials. Thus, the new results suggest that the ocean may have been responsible for the “special stability” of the Holocene climate.

The same processes are at work today: The absorption of carbon by the ocean is slowing the rise in atmospheric carbon dioxide produced by fossil fuel burning, and the upwelling of the Southern Ocean is still allowing some of that carbon dioxide to vent back into the atmosphere.

“If the findings from the Holocene can be used to predict how Southern Ocean upwelling will change in the future, it will improve our ability to forecast changes in atmospheric carbon dioxide and thus in global climate,” said Sigman.

Source: Princeton University [July 30, 2018]





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