среда, 27 февраля 2019 г.

Achavanich Prehistoric Stone Complex, nr Lybster, The Highlands, Scotland, 21.2.19.




Achavanich Prehistoric Stone Complex, nr Lybster, The Highlands, Scotland, 21.2.19.









Source link


Wrapped Up Safely To ensure effective signal transmission, the…


Wrapped Up Safely


To ensure effective signal transmission, the long projections of neurons, the axons, are coated in a protective substance known as myelin. In patients suffering from multiple sclerosis, their immune system attacks this myelin sheath, damaging the neurons and disrupting neural signalling. Under normal circumstances, neural stem cells (NSCs) in the brain can mature into myelin-producing cells – oligodendrocytes (pictured, with nuclei in blue, myelin in green) – to repair any damage. Researchers investigating this process found that, in mice, a protein named Chi3l3 stimulates the production of oligodendrocytes by triggering a cascade of signals that guide NSCs towards becoming oligodendrocytes. Closely-related human proteins, CHIT1 and CHI3L1, have a similar effect on human NSCs, suggesting that they could be a promising target for future research, to ultimately boost the brain’s ability to fight diseases like multiple sclerosis.


Written by Emmanuelle Briolat



You can also follow BPoD on Instagram, Twitter and Facebook


Archive link


The Steppe Maykop enigma

Who were the Steppe Maykop people exactly? Their ancestry must surely rank as one of the biggest surprises served up by ancient DNA to date.
I always thought that they’d turn out roughly like a mixture between populations associated with the Kura-Araxes and Yamnaya cultures (mostly because their territory was located sort of in between them). Nope, that wasn’t even close. This is where they cluster compared to Kura-Araxes and Yamnaya samples in my Principal Component Analysis (PCA) of world-wide genetic variation: the Global25.



To explore the ancestry of the Steppe Maykop people in more detail I ran a couple of unsupervised Global25/nMonte tests, using basically every ancient population in the (scaled) Global25 datasheet that seemed chronologically sensible and even remotely relevant. I narrowed things down to these two mixture models.



Steppe_Maykop
Geoksiur_Eneolithic,11.2
Piedmont_Eneolithic,44.4
West_Siberia_N,44.4
distance%=1.5161
Steppe_Maykop
Piedmont_Eneolithic,46.6
Sarazm_Eneolithic,10.4
West_Siberia_N,43
distance%=1.6408



But, you might say, Global25/nMonte isn’t a published analytical method and it doesn’t run on formal statistics, the meat and potatoes of ancient DNA papers. OK then, let’s try the same models with the qpAdm software, which is a published method and does run on formal statistics, using exactly the same samples.



Steppe_Maykop
Geoksiur_Eneolithic 0.100±0.032
Piedmont_Eneolithic 0.433±0.053
West_Siberia_N 0.467±0.028
chisq 19.155
tail prob 0.159096
Full output
Steppe_Maykop
Piedmont_Eneolithic 0.429±0.051
Sarazm_Eneolithic 0.119±0.033
West_Siberia_N 0.452±0.026
chisq 18.090
tail prob 0.202699
Full output



Basically identical. Importantly, my models must reflect reality at some level, otherwise it’s extremely unlikely that I’d be able to produce a pair of essentially identical results using two such vastly different statistical methods. So the pertinent question is what do these results actually mean?
I didn’t get a chance to put together a map for this blog post. I’ll try and do that tomorrow, because when looking at the locations of the potential mixture sources in my models, it seems unlikely to me that we’re dealing here with a highly complex three-way mixture process, including populations from such far flung locations as western Siberia and southern Central Asia. Rather, I suspect that Steppe Maykop was the result of a two-way mixture between Piedmont_Eneolithic (the population that lived before it on the steppe north of the Caucasus) and someone just a little bit more easterly. I’m guessing that the latter was the (as yet unsampled) population associated with the Kelteminar archeological culture.
Like I say, I’ll add to this blog entry tomorrow. Meantime, feel free to let me know in the comments below if there are models that more accurately capture the ancestry of the Steppe Maykop people, and I might incorporate them into my effort. See also…
On Maykop ancestry in Yamnaya
Big deal of 2018: Yamnaya not related to Maykop
Late PIE ground zero now obvious; location of PIE homeland still uncertain, but…

Source


Ottoman edict allowing Lord Elgin to remove Parthenon Sculptures non existent say experts

According to experts, Lord Elgin plundered the Acropolis monument without the Sultan’s permission. This argument defies the British Museum’s claim that there was an Ottoman firman that allowed him to take the sculptures.











Ottoman edict allowing Lord Elgin to remove Parthenon Sculptures non existent say experts
19th century watercolour of the Acropolis by Edward-Dodwell (1767-1832)
[Credit: Benaki Museum]

According to the British Museum, Elgin removed the Parthenon Sculptures with permission from the Sultan, however this document is not saved, and what the Museum has in its archives, is a later translation into Italian, of a friendly letter from Kaimakam Pasha, authorizing Elgin to take casts of the sculptures but did not authorize him to cause any damages to the monument, says the Honorary General Director of Antiquities, Eleni Korka.
Ms. Korka also stressed the fact that the letter was not by the Sultan himself but by Kaimakam Pasha, who was in Constantinople at the time, replacing the Grand Vizier, and is not an official Ottoman document.



The British argue that they have other documents besides this, however, Iranian researcher Sarian Panahi, one of the few historians who can read Ottoman Turkish and has researched all official documents of the Ottoman Empire, underlines that there is no firman for the transfer of the sculptures.
This fact was confirmed by two Turkish researchers in an interview they gave at the Acropolis Museum. In particular, Turkish researchers Zeynep Aygen and Orhan Sakin presented the results of a long study of the Ottoman Empire’s official documents, which are related to Lord Elgin and stressed the fact that: “All the firmans as well as their contents, were written in a special book “.


Sakin rejected the British claim that Elgin’s documents gave him the permission to export the Marbles. “First of all, this was not a firman. Perhaps, it was a personal letter, but not a firman. The firman could only be signed by the Sultan, not by the Pasha. There was only a permit to visit”, said the Turkish researcher.


Source: ERT [February 25, 2019]



TANN



Archive


2019 February 27 Magnetic Orion Image Credit & Copyright:…


2019 February 27


Magnetic Orion
Image Credit & Copyright: NASA, SOFIA, D. Chuss et al. & ESO, M. McCaughrean et al.


Explanation: Can magnetism affect how stars form? Recent analysis of Orion data from the HAWC+ instrument on the airborne SOFIA observatory indicate that, at times, it can. HAWC+ is able to measure the polarization of far-infrared light which can reveal the alignment of dust grains by expansive ambient magnetic fields. In the featured image, these magnetic fields are shown as curvy lines superposed on an infrared image of the Orion Nebula taken by a Very Large Telescope in Chile. Orion’s Kleinmann-Low Nebula is visible slightly to the upper right of the image center, while bright stars of the Trapezium cluster are visible just to the lower left of center. The Orion Nebula at about l300 light years distant is the nearest major star formation region to the Sun.


∞ Source: apod.nasa.gov/apod/ap190227.html


Tourmaline on Quartz | #Geology #GeologyPage #Mineral Locality:…


Tourmaline on Quartz | #Geology #GeologyPage #Mineral


Locality: Parun pegmatite field, Wama District, Nuristan Province, Afghanistan


Size: 12.5 x 8.4 x 6.2 cm


Photo Copyright © Saphira Minerals


Geology Page

www.geologypage.com

https://www.instagram.com/p/BuYDgfqFxLD/?utm_source=ig_tumblr_share&igshid=1eqskr0bavjnt


Quartz on Wulfenite | #Geology #GeologyPage #Mineral Size: 8 cm…


Quartz on Wulfenite | #Geology #GeologyPage #Mineral


Size: 8 cm


Photo Copyright © Saphira Minerals


Geology Page

www.geologypage.com

https://www.instagram.com/p/BuYD9Xpl0rJ/?utm_source=ig_tumblr_share&igshid=6vwug95vsedp


Blue Lake Cave, Brazil | #Geology #GeologyPage #Brazil Blue…


Blue Lake Cave, Brazil | #Geology #GeologyPage #Brazil


Blue Lake Cave is a cave located in Bonito, Mato Grosso do Sul, Brazil. The cave has been listed as a protected area by IPHAN since 1978.


Gruta Do Lago Azul, or the Blue Lake Grotto, the large cave is filled with a pool of astonishingly clear blue water. Thought to be over 200 feet deep, the water turns a particularly beautiful blue when sunlight shines through a hole in the ceiling of the cave, and makes the water shimmer in the light.


Geology Page

www.geologypage.com

https://www.instagram.com/p/BuYFPixFVHp/?utm_source=ig_tumblr_share&igshid=2pq8w9mnhbt6


Dark Matter May be Hitting the Right Note in Small Galaxies


Fig 1: Astronomers observed that the dark matter does not seem to clump very much in small galaxies, but their density peaks sharply in bigger systems such as clusters of galaxies. It has been a puzzle why different systems behave differently. (Credit: Kavli IPMU – Kavli IPMU modified this figure based on the image credited by NASA, STScI)


Dark matter may scatter against each other only when they hit the right energy, say researchers in Japan, Germany, and Austria in a new study. Their idea helps explain why galaxies from the smallest to the biggest have the shapes they do.


Dark matter is a mysterious and unknown form of matter that comprises more than 80 per cent of matter in the Universe today. Its nature is unknown, but it is believed to be responsible for forming stars and galaxies by its gravitational pull, which led to our existence.


“Dark matter is actually our mom who gave birth to all of us. But we haven’t met her; somehow, we got separated at birth. Who is she? That is the question we want to know,” says paper author Hitoshi Murayama, a University of California Berkeley Professor and Kavli Institute for the Physics and Mathematics of the Universe Principal Investigator.


Astronomers have already found dark matter does not seem to clump together as much as computer simulations suggest. If gravity is the only force that drives dark matter, only pulling and never pushing, then dark matter should become very dense towards the center of galaxies. However, especially in small faint galaxies called dwarf spheroidals, dark matter does not seem to become as dense as expected toward their centers.


This puzzle could be solved if dark matter scatters with each other like billiard balls, allowing them to spread out more evenly after a collision.


But one problem with this idea is that dark matter does seem to clump in bigger systems such as clusters of galaxies. What makes dark matter behave differently between dwarf spheroidals and clusters of galaxies? An international team of researchers has developed an explanation that could solve this riddle, and reveal what dark matter is.



Fig 2a: When two dark matter particles approach each other, then tend to simply pass each other. 

Credit: Kavli IPMU



Fig 2b: But when they come at a special speed, they “resonate” and stick with each other for a brief moment, and move out to different directions afterwards, causing them to scatter. This way, dark matter can spread out so that we can understand smooth profile in small galaxies. (Credit: Kavli IPMU)


“If dark matter scatters with each other only at a low but very special speed, it can happen often in dwarf spheroidals where it is moving slowly, but it is rare in clusters of galaxies where it is moving fast. It needs to hit a resonance” says Chinese physicist Xiaoyong Chu, a postdoctoral researcher at the Austrian Academy of Sciences.


Resonance is a phenomenon that appears every day. To swirl wine in a glass to get it more oxygen so that it lets out more aroma and softens its taste, you need to find the right speed to circle the wine glass. Or you dial old analog radios to the right frequency to tune into your favorite station. These are all examples of resonance, says Murayama. The team suspects this is precisely what dark matter is doing.


“As far as we know, this is the simplest explanation to the puzzle. We are excited because we may know what dark matter is sometime soon,” says Murayama.


However, the team was not convinced that such a simple idea would explain the data correctly.


“First, we were a bit skeptical that this idea will explain the observational data; but once we tried it, it worked like a charm!” says Colombian researcher Camilo Garcia Cely, a postdoctoral researcher at the Deutsches Elektronen-Synchrotron (DESY) in Germany.


The team believes it is no accident that dark matter can hit the exact right note.


“There are many other systems in nature that show similar accidents: in stars alpha particles hit a resonance of beryllium, which in turn hits a resonance of carbon, producing the building blocks that gave rise to life on Earth. A similar process happens for a subatomic particle called phi,” says Garcia Cely.




Fig 3: Using the idea of resonance, the plot demonstrates that we can explain all systems at the same time.

Credit: Xiaoyong Chu, Camilo Garcia Cely, Hitoshi Murayama



“It may also be a sign that our world has more dimensions than we see. If a particle moves in extra dimensions, it has energy. For us who don’t see the extra dimension, we think the energy is actually a mass, thanks to Einstein’s E=mc2. Perhaps some particle moves twice as fast in extra dimension, making its mass precisely twice as much as the mass of dark matter,” says Chu.


The team’s next step will be to find observational data that backs their theory.


“If this is true, future and more detailed observation of different galaxies will reveal that scattering of dark matter indeed depends on its speed,” says Murayama, who is also leading a separate international group that intends to do precisely this using the under construction Prime Focus Spectrograph. The US$80 million instrument will be mounted on the Subaru telescope atop Mauna Kea on Big Island, Hawaii, and will be capable of measuring the speeds of thousands of stars in dwarf spheroidals.

The team’s paper was published online on 22 February by Physical Review Letters.



Fig 4: Paper authors (from left) Xiaoyong Chu, Camilo Garcia Cely, and Hitoshi Murayama 

Credit from left: Xiaoyong Chu, DESY, Kavli IPMU





Paper details

Journal: Physical Review Letters
Title: Velocity Dependence from Resonant Self-Interacting Dark Matter
Authors: Xiaoyong Chu (1), Camilo Garcia-Cely (2), Hitoshi Murayama (3, 4, 5, 2)



Author affiliations:


1. Institute of High Energy Physics, Austrian Academy of Sciences, Nikolsdorfer Gasse 18, 1050 Vienna, Austria
2. Deutsches Elektronen-Synchrotron DESY, Notkestrasse 85, 22607 Hamburg, Germany
3. Department of Physics, University of California, Berkeley, CA 94720, USA
4. Kavli Institute for the Physics and Mathematics of the Universe, The University of Tokyo, 5-1-5 Kashiwanoha, Kashiwa, Chiba 277-8583, Japan
5. Ernest Orlando Lawrence Berkeley National Laboratory, Berkeley, CA 94720, USA


DOI: 10.1103/PhysRevLett.122.071103 (Published 22 February, 2019)




Images & Video


Click here to download images and video.



Research contact

Hitoshi Murayama
Principal Investigator
Kavli Institute for the Physics and Mathematics of the Universe
University of Tokyo
E-mail: hitoshi.murayama@ipmu.jp



Media contact

Motoko Kakubayashi
Press officer
Kavli Institute for the Physics and Mathematics of the Universe
University of Tokyo
Tel:04-7136-5980
E-mail: press@ipmu.jp



Archive link


Proximity to land determines how coral reef communities respond to climate change events

Location, location, location: Proximity to the mainland determines how coral reef communities respond to major environmental disturbances











Proximity to land determines how coral reef communities respond to climate change events
Coral bleaching [Credit: Laura Richardson]

Severe weather and environmental disturbances, such as cyclones or thermal coral bleaching, affect specific areas of coral reefs differently, new research has shown.


A new international study has found that the marine wildlife that live amongst the coral are affected differently by devastating climate change events, depending on how close to the mainland they are found.


The research, co-authored by Laura Richardson from the University of Exeter, studied the effect of the natural disasters on the Great Barrier Reef (GBR) – which is home to more than 1,500 species of fish including clownfish, parrotfish and lionfish.


The research studied three specific areas of the GBR – the inner reefs closest to the mainland, middle-shelf reefs, and outer-shelf reefs, where the continental shelf drops off into the Coral Sea. Surveys of fish and coral reef habitat were made both five years before and six months after two severe cyclones and a mass coral bleaching event.


While those environmental events caused substantial and widespread loss of coral across all reefs, the numbers of herbivorous fishes remained stable (inner-shelf reefs) or even increased (middle- and outer-shelf reefs).


Dr Richardson, a marine biologist at the University of Exeter’s Penryn Campus said: “After widespread loss of corals due to large storms or severe coral bleaching events, herbivorous reef fish are vital for removing seaweed that starts to grow over the dead corals, so that new corals can grow, and surviving corals can recover.


“Understanding how these herbivorous fish respond across the continental shelf highlights where reefs may be more vulnerable and possibly slower to recover. The increased number of herbivorous fish on some reefs in this study is highly promising as they can help prevent the proliferation of seaweed after these huge disturbances.”











Proximity to land determines how coral reef communities respond to climate change events
Lead-author Eva McClure during the study [Credit: Laura Richardson]

Importantly, however, the study showed that the number of herbivorous fish species decreased following the environmental events.


“The loss of species is of greatest concern, affecting the functioning of these reefs and their capacity to respond to future disturbances. It may be setting these reefs up for future ecological surprises” said Dr Hoey from James Cook University in Australia.


The researchers believe the study – the first of its kind – offers a pivotal insight to allow for better conservation and management of coral reefs found worldwide, particularly those reefs exposed to land-based sources of pollution and sedimentation.


The lead-author of the study, Eva McClure from James Cook University, said: “On coral reefs, it is common to find distinct communities of coral and reef fish living together at different locations across the continental shelf.


“But until now, we haven’t known whether these different communities respond in the same way to environmental disturbances or whether specific local conditions might result in different community responses whether close to the mainland or further from shore.”


Coral reefs are made up of thin layers of calcium carbonate (limestone) secreted over thousands of years by billions of tiny soft bodied animals called coral polyps. They are amongst the world’s most diverse marine ecosystems and are home to thousands of species of plants and animals.


The Great Barrier Reef is the world’s largest coral reef, stretching along the northeast coast of Australia, from the northern tip of Queensland, to just north of Bundaberg. However, the biggest differences in coral and fish communities tend to occur from east to west across the Great Barrier Reef.


For the study, conducted by the University of Exeter and James Cook University in Australia, the researchers looked at coral reefs in three distinct positions across the breadth of the continental shelf to compare how the marine life and habitat were affected by the loss of coral following severe environmental disturbances.


While each region was impacted by the disturbances, the research showed that the number of seaweed-eating fish increased on the middle and outer shelf areas, but not in the areas closest to the coast.


The researchers believe that the study not only offers a unique insight into how the reefs are impacted by severe environmental conditions, but also the potential for recovery shown by each specific region.


The findings are published in the journal Diversity.


Source: University of Exeter [February 22, 2019]



TANN



Archive


Diving into Earth’s interior helps scientists unravel secrets of diamond formation

Understanding the global carbon cycle provides scientists with vital clues about the planet’s habitability.











Diving into Earth's interior helps scientists unravel secrets of diamond formation
Two opposed diamond anvils in a diamond anvil cell edge 
[Credit: University of Bristol]

It’s the reason why the Earth has a clement stable climate and a low carbon dioxide atmosphere compared to that of Venus, for instance, which is in a runaway greenhouse state with high surface temperatures and a thick carbon dioxide atmosphere.


One major difference between Earth and Venus is the existence of active plate tectonics on Earth, which make our environment unique within our solar system.


But the atmosphere, oceans, and Earth’s crust are only part of the story. The mantle, which represents 75% of Earth’s volume, potentially holds more carbon than all other reservoirs combined.


Carbon – one of the essential building blocks of organic life – is taken into Earth’s interior by subduction, where it drastically lowers the melting point of the solid mantle, forming carbonated melts (carbon-rich molten rocks) in the shallow mantle, fuelling surface volcanoes. Carbonate minerals may also be transported much deeper into the Earth, reaching the lower mantle, but what happens next is uncertain.


Answering that question is beset with challenges – conditions deep within the Earth are extreme and samples from the mantle are rare. The solution is to recreate those conditions in the lab using sophisticated technology.


Now a team of experimental geoscientists from the University of Bristol have done just that. Their results, published open access in Earth and Planetary Science Letters, uncover new clues about what happens to carbonate minerals when they are transported into the mantle via subduction of the oceanic crust (where one of Earth’s tectonic plates slides below another).


Their findings have uncovered a barrier to subduction of carbonate beyond depths of around 1,000km, where it reacts with silica in the oceanic crust to form diamonds that are stored in the deep Earth over geological timescales.


Dr James Drewitt from the School of Earth Sciences explains: “Do carbonate minerals remain stable through the Earth’s lower mantle, and if not, what pressure/temperature changes does it take to spark reactions between the minerals and what do they look like? These are the questions we wanted to find the answers to – and the only way to get those answers was to reproduce the conditions of the Earth’s interior.”


Dr Drewitt and his team subjected synthetic carbonate rocks to very high pressures and temperatures comparable to deep Earth conditions of up to 90 GPa (about 900,000 atmospheres) and 2000 degrees C using a laser-heated diamond anvil cell. They found that carbonate remains stable up to depths of 1,000-1,300km, almost halfway to the core.


Under these conditions carbonate then reacts with surrounding silica to form a mineral known as bridgmanite, which forms most of the Earth’s mantle. The carbon released by this reaction is in the form of solid carbon dioxide. As the hot surrounding mantle eventually heats up the subducted slab, this solid carbon dioxide breaks down to form superdeep diamonds.


Dr Drewitt adds: “Eventually the superdeep diamonds could be returned to the surface in upwelling mantle plumes, and this process could represent one of the sources of superdeep diamonds that we find at the surface and which provide the only direct evidence we have of the composition of the deep earth.


“This is exciting because the deepest humans have ever been able to drill is about 12 km, less than half the depth of Earth’s crust. This pales in comparison to the massive scale of Earth’s mantle, which extends to nearly 3,000 km depth.”


The team used a diamond anvil cell to generate pressures equivalent to those found at these depths, loading samples under a microscope into a pressure chamber drilled out of a metal gasket which is then compressed between the gem quality, brilliant cut diamond anvils. The crystal structure of those samples was then analysed using x-ray diffraction at the UK synchrotron facility in Oxfordshire.


Dr Drewitt now plans to apply these high pressure and high-temperature experiments along with advanced computer simulation techniques to other minerals and materials, adding: “As well as carbon, there is potentially several ocean’s worth of water transported deep into the mantle, and when released this will induce melting of Earth’s upper and lower mantle.


“However, we cannot adequately test or understand current models of the dynamic behaviour of this water rich molten rock because we do not know their composition or their physical properties. The experiments at extreme conditions and advanced computer simulations that we are currently working on will help to resolve these problems.”


Source: University of Bristol [February 22, 2019]



TANN



Archive


Extinct weasel relative with confounding skull likely ate meat with a side of veggies

New research on an extinct weasel relative reveals what it might have eaten when it lived in North America and Asia about 20 million years ago. The oddly shaped skull of Leptarctus primus has long led to conflicting theories about its diet. But the new work, based on biomechanical modeling and published this week in the Journal of Vertebrate Paleontology, shows that Leptarctus was likely a carnivorous predator, with capability for omnivory and a broader diet when prey was scarce, and had a skull that functioned similarly to that of the living American badger.











Extinct weasel relative with confounding skull likely ate meat with a side of veggies
Digital model of the skull of Leptarctus primus, showing reconstructed jaw muscle groups in red, yellow, and pink.
The virtual muscles were activated in bite simulations to test the biomechanical capability
of this extinct weasel relative [Credit: J. Tseng]

Leptarctus primus, which lived in the Miocene and was just a little larger than a housecat, has intrigued researchers because of its unusual and extremely robust skull.
“For a mammal, its skull is really strange,” said co-author Z. Jack Tseng, a research associate at the American Museum of Natural History and an assistant professor of pathology and anatomical sciences at the Jacobs School of Medicine and Biomedical Science at the University at Buffalo. “It’s heavily built–like a tank–with very thick zygomatic cheek bones. The top of its head looks like it’s wearing a helmet.”


Strikingly, Leptarctus primus has two parallel ridges that line the top of the head (other carnivorans typically have a single central ridge or have smooth skulls). For many years, paleontologists have debated the ecological niche of Leptarctus based on conflicting interpretations of the strong parallel skull ridges, distinctive skull shape, and the shape of its teeth and chewing wear.











Extinct weasel relative with confounding skull likely ate meat with a side of veggies
A reconstruction of the skull (upper) and head (lower) of Leptarctus primus, an extinct
weasel relative that lived in North America and Asia about 20 million years ago
[Credit: AMNH/N. Wong]

Previous interpretations of their feeding lifestyle ranged widely, across virtually every type of known feeding behavior in carnivorans (dogs, cats, hyaenas, bears, seals, and weasels and their relatives), including herbivore, carnivore, insectivore, and omnivore. But because of the lack of quantitative research into how Leptarctus skulls functioned, the question of their diets remained unanswered.
In this study, led by Alixandra Prybyla, who was a student in the Museum’s National Science Foundation Summer Research Experience for Undergraduates program while at Columbia University, the researchers took an engineering approach. The team compared an almost complete fossil skull of Leptarctus primus with 18 species of modern carnivorans with known diets as well as to other fossil species, using bite simulations based on CT scans of the skulls and virtual modeling of feeding mechanics.


According to John Flynn, study co-author, research team leader, and Frick curator of fossil mammals in the Museum’s Division of Paleontology, “Traditional methods of studying skull, tooth, and skeleton anatomy are still essential for understanding how fossil species lived. But high-resolution x-ray CT images and sophisticated computerized engineering modeling tools have completely transformed our ability to accurately reconstruct feeding habits in extinct animals.”











Extinct weasel relative with confounding skull likely ate meat with a side of veggies
A reconstruction of the head of Leptarctus primus attacking the Miocene
 rodent Cupidinimus [Credit: AMNH/N. Wong]

They found that among the other species analyzed, the skull of Leptarctus is mechanically most similar to the skull of the American badger. Despite some differences in their skull appearances, the computer simulations indicate that the badger is the best living biomechanical analog for understanding the dietary lifestyle of Leptarctus. Based upon those comparisons, the team determined that it was primarily a carnivore and an active predator, but that it could also have been an omnivore feeding on a wider range of plant and insect foods when necessary.


“It was probably hunting down prey and taking in whatever it had access to most of the time,” Tseng said.


Prybyla added: “This complete skull of Leptarctus represents an untapped wellspring of information on the history of ancient relatives of weasels, otters, badgers, and skunks. It’s wonderful what one specimen can illuminate for researchers. To spearhead a project of this magnitude as an undergraduate student was extremely empowering.”


The researchers will conduct future studies using similar engineering modeling tools to look at variations in skull feeding mechanics among other species in the leptarctine group, to determine how many different types of feeding adaptations may have existed among these unusual extinct predators.


Source: American Museum of Natural History [February 22, 2019]



TANN



Archive


Scientists find routine allomaternal nursing in an Old World monkey

A team of scientists led by Prof. LI Ming of the Institute of Zoology, Chinese Academy of Sciences, found widespread allomaternal nursing behavior in nursing others’ offspring in an Old World monkey, the golden snub-nosed monkey.











Scientists find routine allomaternal nursing in an Old World monkey
A mother is simultaneously suckling two infants in the same social unit
[Credit: IOZ]

The evolution of lactation in metatherian and eutherian mammals has resulted in a large degree of nutritional and developmental dependency between a female and her offspring.


Milk production is energetically costly for mothers since they need to synthesize and provide nutrients, hormones, vitamins, and immune compounds. Therefore, lactating females should be reluctant to invest time or energy in nursing others’ offspring.


While regular allomaternal nursing has been documented in a number of rodent and carnivore species, as well as in some prosimians, New World monkeys and humans, it is not common in Old World monkeys and apes.


Based on more than eight years of field observation of infants and their mothers at Shennongjia National Park, Central China, as well as analysis of the monkeys’ reproductive histories, the study provides the first evidence of regular allomaternal nursing in golden snub-nosed monkeys and expands the taxonomic distribution of this behavior in primates to Old World monkeys.


The study found that most infants of golden snub-nosed monkeys were allonursed by one or two additional adult females besides the biological mother. Allomaternal nursing was largely confined to the first three months of the infant’s life, and mainly practiced by related females who reciprocally nursed each other’s offspring. Therefore, the study supports kin selection and reciprocity hypotheses and provides an evolutionary explanation for allomaternal nursing in golden snub-nosed monkeys.











Scientists find routine allomaternal nursing in an Old World monkey
(A) increased allomaternal nursing within mother-daughter dyads, (B) positive relationship between mother’s and
allonurser’s pattern of reciprocal allomaternal nursing (C) no difference in allomaternal nursing proportions
 between females with an unweaned infant (approximately one year of age) and females with a neonate (< 6 months
of age), (D) no difference in allomaternal nursing proportions between primiparous and multiparous mothers.
 (***, p < 0.001; **, p < 0.01; ns, no significance, p > 0.05) [Credit: LI Ming]

In contrast, the study provides no support for the misdirected parental care hypothesis, which had previously been used to explain allomaternal nursing in primates.
The current study shows that allomaternal nursing enhanced infant survivorship and did not have a negative impact on the future reproductive success of the allonursers. Therefore, considering that similar social and ecological traits typify all primate species that practice allomaternal nursing (including humans), the researchers have proposed that allomaternal nursing might have arisen through natural selection since heavy postnatal energy requirements and harsh or unpredictable environmental conditions placed a premium on shared provisioning.


The current study also shows that reciprocity and relatedness play a significant role in the maintenance of allomaternal nursing in these primates. The researchers observed that mothers permit other females to take their infants as early as their first day of life and let them carry and groom their infants. These female bonds may be mediated through kinship and common residence in the same social unit, as well as other forms of social behavior (e.g., grooming) that promote a set of affiliative and permissive relationships, which are key to the infant-mother-allomaternal caregiver relationship.


Such relationships are also crucial in human social interactions. Therefore, the study expands the taxonomic distribution of allomaternal nursing and provides fresh insights into possible factors driving the evolution of allomaternal nursing behavior in primates, including humans.


The findings were published in Science Advances.


Source: Chinese Academy of Science [February 22, 2019]



TANN



Archive


NASA Selects Mission to Study Space Weather from Space Station


NASA – Goddard Space Flight Center logo.


Feb. 26, 2019


NASA has selected a new mission that will help scientists understand and, ultimately, forecast the vast space weather system around our planet. Space weather is important  because it can have profound impacts – affecting technology and astronauts in space, disrupting radio communications and, at its most severe, overwhelming power grids.


The new experiment will, for the first time, obtain global observations of an important driver of space weather in a dynamic region of Earth’s upper atmosphere that can cause interference with radio and GPS communications.


The Atmospheric Waves Experiment (AWE) mission will cost $42 million and is planned to launch in August 2022, attached to the exterior of the Earth-orbiting International Space Station. From its space station perch, AWE will focus on colorful bands of light in Earth’s atmosphere, called airglow, to determine what combination of forces drive space weather in the upper atmosphere.


Researchers once thought that only the Sun’s constant outflow of ultraviolet light and particles, the solar wind, could affect the region. However, recently they have learned that solar variability is not enough to drive the changes observed, and Earth’s weather also must be having an effect. To help unravel that connection, AWE will investigate how waves in the lower atmosphere, caused by variations in the densities of different packets of air, impact the upper atmosphere.



Image above: An image taken from the International Space Station shows orange swaths of airglow hovering in Earth’s atmosphere. NASA’s new Atmospheric Waves Experiment will observe this airglow from a perch on the space station to help scientists understand, and ultimately improve forecasts of, space weather changes in the upper atmosphere. Image Credit: NASA.


AWE is a Mission of Opportunity under NASA’s Heliophysics Explorers Program, which conducts focused scientific research and develops instrumentation to fill the scientific gaps between the agency’s larger missions. Since the 1958 launch of NASA’s first satellite Explorer 1, which discovered Earth’s radiation belts, the Explorers Program has supported more than 90 missions. The Uhuru and Cosmic Background Explorer (COBE) missions led to Nobel prizes for their investigators.


“The Explorers Program seeks innovative ideas for small and cost-constrained missions that can help unravel the mysteries of the universe and explore our place in it,” said Paul Hertz, NASA’s Director of Astrophysics. “This mission absolutely meets that standard with a creative and cost-effective mission to solve mysteries about Earth’s upper atmosphere.”


AWE was selected for development based on its potential science value and the feasibility of its development plans. The mission is led by Michael Taylor at Utah State University in Logan and it is managed by the Explorers Program Office at NASA’s Goddard Space Flight Center in Greenbelt, Maryland.


NASA also has selected the Sun Radio Interferometer Space Experiment (SunRISE) for a seven-month, $100,000 extended formulation study. SunRISE would be an array of six CubeSats operating like one large radio telescope. This proposed mission would investigate how giant space weather storms from the Sun, called solar particle storms, are accelerated and released into planetary space.  


While SunRISE has not yet demonstrated its readiness for the next phase of mission development, the proposed concept represents a compelling use of new NASA-developed technology. SunRISE is led by Justin Kasper at the University of Michigan in Ann Arbor and managed by NASA’s Jet Propulsion Laboratory in Pasadena, California.


The Explorers Program, the oldest continuous NASA program, is designed to provide frequent, low-cost access to space using principal investigator-led space science investigations relevant to the work of NASA’s Science Mission Directorate in astrophysics and heliophysics.


The program is managed by Goddard for the Science Mission Directorate, which conducts a wide variety of research and scientific exploration programs for Earth studies, space weather, the solar system and universe.


For more information about the Explorers Program, visit: https://explorers.gsfc.nasa.gov


For information about NASA missions and activities, visit: https://www.nasa.gov


Image (mentioned), Text, Credits: NASA/Dwayne Brown.


Greetings, Orbiter.chArchive link


Next Crew Arrives at Launch Site as Station Preps for First SpaceX Crew Dragon


ISS – Expedition 58 Mission patch.


February 26, 2019


The Expedition 59-60 crew arrived at the Baikonur Cosmodrome launch site in Kazakhstan today. Commander Alexey Ovchinin and Flight Engineers Nick Hague and Christina Koch are final training before their March 14 liftoff aboard the Soyuz MS-12 spacecraft. They will take a six-hour ride to their new orbital home where they will live and work until October.


Meanwhile, the Expedition 58 crew is back at today aboard the International Space Station after taking the day off Monday. The orbital lab is also flying at higher altitude to get ready for the arrival Russian crew and cargo ships starting next month.




Image above: Expedition 59 crew members (from left) Christina Koch, Alexey Ovchinin and Nick Hague are pictured before departing for their launch site at the Baikonur Cosmodrome in Kazakhstan. Image Credit: Roscosmos.


The space station is orbiting two miles higher at its perigee after the docked Progress 71 resupply ship fired its engines for seven minutes and 31 seconds Monday night. This places the station at the correct altitude for the March 14 arrival of the Expedition 59-60 crew and the Progress 72 cargo craft docking on April 4.


The station astronauts are training all week for the arrival of the first SpaceX Crew Dragon spaceship this weekend. The uncrewed SpaceX DM-1, or Demonstration Mission-1, will launch Saturday at 2:49 a.m. EST from Kennedy Space Center in Florida. The Crew Dragon will arrive at the station on Sunday and dock around 6 a.m. to the International Docking Adapter (IDA) on the Harmony module.



Crew Dragon’s approach and dock to ISS. Image Credits: SpaceX/NASA

Astronauts Anne McClain and David Saint-Jacques will monitor the Crew Dragon’s approach and rendezvous on Sunday. The vehicle is targeting a 6 a.m. EST docking to the IDA where the hatches will swing open about two-and-a-half hours later. It will undock on March 8 and return to Earth with a splashdown in the Pacific Ocean ending its mission.


Related links:


Expedition 58: https://www.nasa.gov/mission_pages/station/expeditions/expedition58/index.html


Expedition 59-60: https://www.nasa.gov/mission_pages/station/expeditions/future.html


Progress 71: https://blogs.nasa.gov/spacestation/2018/11/16/russias-cargo-craft-blasts-off-to-station-for-sunday-delivery/


SpaceX DM-1: https://www.nasa.gov/press-release/nasa-spacex-demo-1-briefings-events-and-broadcasts


International Docking Adapter (IDA): https://www.nasa.gov/feature/meet-the-international-docking-adapter


Harmony module: https://www.nasa.gov/mission_pages/station/structure/elements/harmony


Space Station Research and Technology: https://www.nasa.gov/mission_pages/station/research/index.html


International Space Station (ISS): https://www.nasa.gov/mission_pages/station/main/index.html


Images (mentioned), Text, Credits: NASA/Mark Garcia.


Best regards, Orbiter.chArchive link


Simultaneous X-ray and infrared observations of the galactic centre

The supermassive black hole (SMBH) at the centre of our Milky Way galaxy, Sagittarius A*, is by far the closest such object to us, only about 25 thousand light-years away. Although not nearly as active or luminous as other SMBHs, its relative proximity provides astronomers with a unique opportunity to probe what happens close to the “edge” of a black hole.











Simultaneous X-ray and infrared observations of the galactic centre
A visualization of simulated flaring activity and clouds of material around the supermassive black hole in the galactic
centre. Astronomers observing these events at X-ray and infrared wavelengths simultaneously report evidence
that the X-ray emission often precedes the infrared by ten to twenty minutes, consistent with one
class of theoretical models [Credit: ESO, Gfycat]

Monitored in the radio since its discovery and more recently in the infrared and the X-ray, Sgr A* appears to be accreting material at a very low rate, only a few hundredths of an Earth-mass per year. Its X-ray emission is persistent, probably resulting from the rapid motions of electrons in the hot accretion flow associated with the black hole.


Once a day there are also flares of emission that are highly variable; they appear more often in the infrared than in X-rays. Some submillimeter wavelength flares have also been tentatively linked to IR flares, although their timing seems to be delayed with respect to infrared events. Despite these intensive observational efforts, the physical mechanisms producing flaring around this SMBH are still unknown and are the topic of intense theoretical modeling.


CfA astronomers Steve Willner, Joe Hora, Giovanni Fazio, and Howard Smith joined their colleagues in undertaking a systematic campaign of simultaneous multiwavelength observations of flaring in SagA* using the Spitzer and Chandra observatories (the Submillimeter Array was also used in some of the series).


In over one hundred hours of data taken over four years (the longest such dataset ever obtained), the team observed four flare events in both X-ray and infrared in which the X-ray event appears to lead the infrared by ten to twenty minutes.


The correlation between the observed peaks implies there is some physical connection between them, and the slight timing difference is in agreement with models that describe the flares as coming from magnetically driven particle acceleration and shocks.


Exactly simultaneous events can’t be completely ruled out, however, but the results are nevertheless inconsistent with some of the more exotic models that involve the relativistic motion of electrons. If future simultaneous observations planned for the summer of 2019 also see flaring, they can provide new constraints on the time lag and on associated physical models.


The findings are published in The Astrophysical Journal.


Source: Harvard-Smithsonian Center for Astrophysics [February 25, 2019]



TANN



Archive


Unprecedented biological changes in the global ocean

Current monitoring of marine biological systems only covers a tiny fraction of the ocean, which limits our ability to confidently predict the expected effects of climate disturbances on marine biodiversity.  Using a new computer model, an international team led by the CNRS and involving, in France, researchers from Sorbonne University has demonstrated that biological changes are accelerating, which has consequences for our use of marine resources. Their findings are published in Nature Climate Change.


Unprecedented biological changes in the global ocean










Unprecedented biological changes in the global ocean
By way of illustration, here are two applications of the model, for the periods running from 2005 to 2009 (top)
and from 2010 to 2014 (bottom). Red indicates substantial biological changes; yellow,
minor changes. No colour means no change [Credit: Grégory Beaugrand]

Across time, marine biological systems have experienced changes of varying magnitude due to natural climatic fluctuations. Abrupt biological shifts—dubbed “climate surprises”—have also been detected in many regions of the ocean. To understand these shifts, whether sudden and unexpected or stretched out over longer periods, scientists from the CNRS and Sorbonne University,  with colleagues from European, American, and Japanese research institutes, developed a novel approach based on the macroecological theory on the arrangement of life (METAL). To construct their computer model, the researchers designed a large number of simulated species (“pseudo-species”) exhibiting a wide range of responses to natural temperature variations. These pseudo-species, which avoid thermal fluctuations beyond their range of tolerance, form “pseudo-communities” and gradually colonize all oceanic regions in the model.
Marine biodiversity monitoring programs only cover a small area of the ocean and usually only within regions near the coast. This new model based on the METAL theory offers global coverage and permits rapid identification of major biological shifts that can strongly impact marine biodiversity and associated ecosystem services like fishing, aquaculture, and the carbon cycle. When initially tested for fourteen oceanic regions, the model accurately predicted actual biological changes observed in the field since the 1960s. By next applying the model to the global ocean, the researchers were able to quantify the force and spatial extent of these biological shifts. The model also allowed them to draw attention to a recent, unheard-of rise in the number of “climate surprises,” which may likely be attributed to El Niño, temperature anomalies of the Atlantic and the Pacific, and Arctic warming.
In most cases, the model predicts an event one year before it occurs, making it possible to identify regions overlooked by current field observation programs where biodiversity is under threat. Though marine biodiversity provides humans with 80 million metric tons of fish and invertebrates annually, the changes revealed by this new computer model may redistribute ocean communities and species worldwide in ways that may benefit or harm mankind.


Source: CNRS [February 25, 2019]



TANN



Archive


New comparative study on DNA modifications across the fungal tree of life

DNA activity can change without changing the sequence of the DNA segment itself. Gene activation and inactivation can be the basis for how species produce unique individuals. Some processes that change gene activity are well understood in the context of model species. However, scientists are still grappling with how some processes, like DNA methylation, change gene activity in many diverse organisms. Broader theories applicable to all species have proven elusive, given the amount of natural variability on Earth.











New comparative study on DNA modifications across the fungal tree of life
Credit: University of Georgia

Now, a group of scientists have published a study in Nature Ecology and Evolution comparing and relating DNA methylation across 40 diverse fungal species. The paper, part of a larger effort to develop a unified theory of DNA methylation, begins to fill a taxonomic gap for the “rules” associated with DNA methylation that are conserved across species, as well as where and why they have diverged.


“Undoubtedly, differences in DNA determine the observable characteristics of individuals,” said Adam Bewick, postdoctoral research associate in the University of Georgia Franklin College of Arts and Sciences Department of Genetics and first author on the new paper. “However, an increasing amount of evidence suggests that heritable alterations to how DNA is expressed, without changes to the DNA sequence can contribute to or determine these characteristics. One way that expression differences are achieved is through modifications, like a methyl group that attaches to DNA.”


In collaboration with colleagues at UGA, University of California, Riverside, University of Michigan, and the Joint Genome Institute, the research team compared DNA and other modifications to characteristics across a wide and diverse sampling of species.


“DNA methylation and other modifications have significant implications for our understanding of natural variation and how it changes over time,” Bewick said.


One of the key findings is that gene expression isn’t likely affected directly by DNA methylation in fungi but may serve a role in genome integrity.


“Through this and other large comparative studies we are gaining a better understanding of how modifications to DNA contribute to variation between and within species and how can we leverage this variation for medical and agricultural advancements.”


Author: Alan Flurry | Source: University of Georgia [February 25, 2019]



TANN



Archive


Ancient wetlands provide new insight into global carbon cycle

Scientists have unearthed and pieced together evidence on more than 1,000 ancient wetland sites from across the globe, that are presently covered by fields, forests and lakes. Although vanished from the Earth’s surface, these buried sites could explain some of the differences between global carbon cycle models and real-life observations.











Ancient wetlands provide new insight into global carbon cycle
Researchers in front of a Yedoma outcrop with multiple buried peat profiles that have been preserved
in permafrost, Eastern Lena River Delta, Siberia, Russia. The buried peat profiles
 protrude from the cliff face [Credit: Guido Grosse (AWI)]

Cliffs, quarries, road construction, and scientific sampling have revealed carbon-rich wetland deposits buried under other kinds of soils and sediments. Many wetlands are characterized by thick deposits of undecomposed plant material (or peat), which is often preserved, resulting in a record of wetland presence. The buried wetlands frequently included coastal marshes that had been flooded by sea level rise, and wetlands that had been buried by glaciers, flooding, or wind-deposited sediments.


The researchers compiled the information about these buried wetland deposits, including where they were found, when they formed, and why they were buried.


“We were really surprised when we started to combine our data from different sites around the world. What we thought would be only a few sites turned out to be just the tip of the iceberg. When we started to look for more examples from previous studies, we identified more than 1,000 buried wetland sites across the globe,” Dr Claire Treat from the University of Eastern Finland says.


The study was led by Dr Treat at the University of Eastern Finland and by Dr Thomas Kleinen at the Max Planck Institute for Meteorology in Germany.


Buried wetland sites were found from high Arctic islands of Canada and Siberia to tropical Africa and Indonesia, to Southern South America and New Zealand. Some formed less than 1,000 years ago, while others formed during the warm climate period between the two latest glaciations more than 100,000 years ago.


Using these records of wetland presence since the beginning of the last interglacial, 130,000 years ago, the researchers found that wetlands in northern latitudes responded to changes in climate. Wetlands formed when the climate was warmer, and many wetlands were buried during periods of glacial advance and cooling temperatures. When it was cold, few new wetlands formed until the climate warmed again. Some of these buried peat sediments remain until today. These new findings of widespread buried peats suggest that, on the whole, peat burial can result in the slow transfer of carbon from the atmosphere to land, ultimately offsetting a small part of climate warming in the past.


“The fact that these peats are buried and stay on land is basically like a leak in what we usually consider a closed system of how carbon moves around the earth, from the atmosphere to the land and oceans. This new finding isn’t represented in our models of the global carbon cycle, and may help to explain some behaviour that differs between models and observations,” Dr Treat from the University of Eastern Finland says.


The results also suggest that present-day wetlands may continue to offset rising atmospheric CO2 concentrations as the climate warms if they remain undisturbed by drainage and wildfires.


The study is published in the Proceedings of the National Academy of Sciences.


Source: University of Eastern Finland [February 25, 2019]



TANN



Archive


Ancient rocks provide clues to Earth’s early history

Oxygen in the form of the oxygen molecule (O2), produced by plants and vital for animals, is thankfully abundant in Earth’s atmosphere and oceans. Researchers studying the history of O2 on Earth, however, know that it was relatively scarce for much of our planet’s 4.6 billion-year existence. So when and where did O2 begin to build up on Earth?











Ancient rocks provide clues to Earth's early history
Stromatolite in Shark Bay, Western Australia. These stromatolites are thought to be some of the most ancient forms
of life on Earth and are comprised of organisms that probably contributed to the O2 scientists are
inferring existed on ancient Earth (i.e., cyanobacteria) [Credit: Ariel Anbar, ASU]

By studying ancient rocks, researchers have determined that sometime between 2.5 and 2.3 billion years ago, Earth underwent what scientists call the “Great Oxidation Event” or “GOE” for short. O2 first accumulated in Earth’s atmosphere at this time and has been present ever since.


Through numerous studies in this field of research, however, evidence has emerged that there were minor amounts of O2 in small areas of Earth’s ancient shallow oceans before the GOE. And in a study published recently in the journal Nature Geoscience, a research team led by scientists at Arizona State University (ASU) has provided compelling evidence for significant ocean oxygenation before the GOE, on a larger scale and to greater depths than previously recognized.


For this study, the team targeted a set of 2.5 billion-year-old marine sedimentary rocks from Western Australia known as the Mt. McRae Shale. “These rocks were perfect for our study because they were shown previously to have been deposited during an anomalous oxygenation episode before the Great Oxidation Event,” says lead author Chadlin Ostrander of ASU’s School of Earth and Space Exploration.


Shales are sedimentary rocks that were, at some time in Earth’s past, deposited on the sea floor of ancient oceans. In some cases, these shales contain the chemical fingerprints of the ancient oceans they were deposited in.











Ancient rocks provide clues to Earth's early history
Stromatolite in Shark Bay, Western Australia. These stromatolites are thought to be some of the most ancient forms
of life on Earth and are comprised of organisms that probably contributed to the O2 scientists are
inferring existed on ancient Earth (i.e., cyanobacteria) [Credit: Ariel Anbar, ASU]

For this research, Ostrander dissolved shale samples and separated elements of interest in a clean lab, then measured isotopic compositions on a mass spectrometer. This process was completed with the help of co-authors Sune Nielsen at Woods Hole Oceanographic Institution (Massachusetts); Jeremy Owens at Florida State University; Brian Kendall at the University of Waterloo (Ontario, Canada); scientists Gwyneth Gordon and Stephen Romaniello of ASU’s School of Earth and Space Exploration; and Ariel Anbar of ASU’s School of Earth and Space Exploration and School of Molecular Sciences. Data collection took over a year and utilized facilities at Woods Hole Oceanographic Institution, Florida State University, and ASU.
Using mass spectrometers, the team measured the thallium and molybdenum isotope compositions of the Mt. McRae Shale. This was the first time both isotope systems had been measured in the same set of shale samples. As hypothesized, a predictable thallium and molybdenum isotope pattern emerged, indicating that manganese oxide minerals were being buried in the sea floor over large regions of the ancient ocean. For this burial to occur, O2 needed to have been present all the way down to the sea floor 2.5 billion-years-ago.


These findings improve scientists’ understanding of Earth’s ocean oxygenation history. Accumulation of O2 was probably not restricted to small portions of the surface ocean prior to the GOE. More likely, O2 accumulation extended over large regions of the ocean and extended far into the ocean’s depths. In some of these areas, O2 accumulation seems to have even extended all the way down to the sea floor.











Ancient rocks provide clues to Earth's early history
The 2.5 billion-year-old Mt. McRae Shale from Western Australia was analyzed for thallium and molybdenum
 isotope compositions, revealing a pattern that indicates manganese oxide minerals were being buried
over large regions of the ancient sea floor. For this burial to occur, O2 needed to have been present
 all the way down to the sea floor 2.5 billion-years-ago [Credit: Chad Ostrander, ASU]

“Our discovery forces us to re-think the initial oxygenation of Earth,” states Ostrander. “Many lines of evidence suggest that O2 started to accumulate in Earth’s atmosphere after about 2.5 billion years ago during the GOE. However, it is now apparent that Earth’s initial oxygenation is a story rooted in the ocean. O2 probably accumulated in Earth’s oceans – to significant levels, according to our data – well before doing so in the atmosphere.”


“Now that we know when and where O2 began to build up, the next question is why” says ASU President’s Professor and co-author Anbar. “We think that bacteria that produce O2 were thriving in the oceans long before O2 began to build up in the atmosphere. What changed to cause that build-up? That’s what we’re working on next.”


Source: Arizona State University [February 25, 2019]



TANN



Archive


Featured

Полет на параплане с обрыва на мысу Куяльницкого лимана, соленого озера. Экстремальный развлекательный полет проводится для любителей. ...

Popular