среда, 1 мая 2019 г.

Little Squirts We inherit our genes from mum and dad, and over…


Little Squirts


We inherit our genes from mum and dad, and over time these DNA blueprints help us develop family similarities. Yet we also receive some of our parents’ epigenetics, chemicals that surround the genes controlling how they are used. Epigenetics are often affected by lifestyle and health, and in this way a mother’s age can directly affect their offspring. In humans, as in sea squirts or rotifers (like this one), elderly mothers often give birth to children who live shorter lives. But recent experiments suggest rotifers with older mothers react much more positively to caloric restriction – a healthy boost caused by a change in diet. As we share many genes in common with rotifers, with careful study this may mean choice of diet, medication or lifestyle might affect human children from young mothers or older mothers differently, and contribute to personalised medicine in the future.


Written by John Ankers



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Smithsonian Launches «Journey through an Exploded Star» 3D Interactive...





Journey through the remnants of an exploded star in this Smithsonian 3D interactive experience.





Image courtesy of the Smithsonian Center for Learning and Digital Access.
 Low Resolution (jpg)



Washington, DC The Smithsonian today made available a new online interactive that allows users to explore a three-dimensional (3D) visualization of the remnants of a supernova, or exploded star.



Designed for use by both general audiences and high school science classrooms, the free materials, available at s.si.edu/supernova, include an interactive simulation, a 360° video, and a multimedia instructional package.


The project was created by the Smithsonian Center for Learning and Digital Access in conjunction with the Center for Astrophysics | Harvard & Smithsonian (CfA), a collaboration that includes the Smithsonian Astrophysical Observatory.


To create the visualizations, the project uses data from the Chandra X-ray Observatory and Spitzer Space Telescope, the National Optical Astronomy Observatory’s Mayall Telescope, and the MIT/Michigan/Dartmouth Observatory’s Hiltner Telescope.


«Journey» features the data visualization work of Kimberly Arcand, visualization and emerging technology lead for Chandra, which is operated and controlled on behalf of NASA by the CfA.

«All of that data has to be translated and processed in a way that humans can see, so it’s really important to be able to study our Universe using different kinds of light,» said Arcand. «Each band of light gives you different information, so it’s like adding puzzle pieces to fit into the greater whole.»

«Journey through an Exploded Star» offers three ways to explore content:


— An online interactive simulation in which users navigate the fiery remains of a supernova and manipulate the real data to make their own visualization of the cosmos. (Closed Captioned, works across desktop browsers, and requires no software downloads.)


— A 360° video tour, narrated by Arcand, explains how and why scientists study supernovas such as Cassiopeia A: to gain a comprehensive picture of the cosmos. (Works on desktop, mobile, and Google Cardboard devices.)


— A high school classroom multimedia instructional package begins with the fundamentals of the electromagnetic spectrum and illustrates the production of elements from the explosions of stars. (Aligned to Next Generation Science Standards (HS-ESS1-3 and HS-PS4).)


The director of the Smithsonian Center for Learning and Digital Access, Stephanie L. Norby, said, «Projects such as this one make science learning both exciting and relevant for students. Using media tools, they can make a personal connection to topics that may initially seem esoteric to discover that there are forces that connect everyone to the stars.»


The Smithsonian Center for Learning and Digital Access makes all of this content freely available in its Smithsonian Learning Lab.


About the Smithsonian Center for Learning and Digital Access


The Smithsonian established the Smithsonian Center for Learning and Digital Access in 1976 to serve public education by bringing Smithsonian collections and expertise into the nation’s classrooms. For more than 40 years, it has published educational materials and provided one access point to Smithsonian educational resources. To understand the needs of teachers, students, and museum educators, the Center spent more than a decade in active experimentation and research, culminating in the launch of a new online platform—the Smithsonian Learning Lab. Since its launch in 2016, museum and classroom educators have used the Lab’s tools to create thousands of new examples—ranging from experiments to models—for using Smithsonian resources for learning. The Center now studies how teachers and students use digital museum resources and broadly disseminates this knowledge through professional development to advance museum and digital learning.


About the Center for Astrophysics | Harvard & Smithsonian


Headquartered in Cambridge, Mass., the Center for Astrophysics | Harvard & Smithsonian (CfA) is a collaboration between the Smithsonian Astrophysical Observatory and the Harvard College Observatory. CfA scientists, organized into six research divisions, study the origin, evolution and ultimate fate of the universe.

For more information, contact:


Darren Milligan
Smithsonian Center for Learning and Digital Access
(202) 633-5291

milligand@si.edu


Tyler Jump
Public Affairs
Center for Astrophysics | Harvard & Smithsonian
+1 617-495-7462

tyler.jump@cfa.harvard.edu





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2019 May 1 The Cat’s Eye Nebula in Optical and X-ray…


2019 May 1


The Cat’s Eye Nebula in Optical and X-ray
Image Credit: NASA, ESA, Hubble Legacy Archive; Chandra X-ray Obs.;
Processing & Copyright: Rudy Pohl


Explanation: To some it looks like a cat’s eye. To others, perhaps like a giant cosmic conch shell. It is actually one of brightest and most highly detailed planetary nebula known, composed of gas expelled in the brief yet glorious phase near the end of life of a Sun-like star. This nebula’s dying central star may have produced the outer circular concentric shells by shrugging off outer layers in a series of regular convulsions. The formation of the beautiful, complex-yet-symmetric inner structures, however, is not well understood. The featured image is a composite of a digitally sharpened Hubble Space Telescope image with X-ray light captured by the orbiting Chandra Observatory. The exquisite floating space statue spans over half a light-year across. Of course, gazing into this Cat’s Eye, humanity may well be seeing the fate of our sun, destined to enter its own planetary nebula phase of evolution … in about 5 billion years.


∞ Source: apod.nasa.gov/apod/ap190501.html


Astrophysicists simulate the sounds of stars to reveal their secrets

Sound may not be able to travel through the vacuum of space. But that doesn’t stop stars from unleashing a symphony of subsonic notes as their nuclear furnaces power complex vibrations. Telescopes can spot these vibrations as fluctuations in the brightness or temperature on the surface of a star.











Astrophysicists simulate the sounds of stars to reveal their secrets
Credit: University of Wisconsin-Madison

Understand these vibrations, and we can learn more about the inner structure of the star that is otherwise hidden from view.


«A cello sounds like a cello because of its size and shape,» says Jacqueline Goldstein, a graduate student in the University of Wisconsin–Madison astronomy department. «The vibrations of stars also depend on their size and structure.»


In her work, Goldstein studies the connection between stellar structure and vibrations by developing software that simulates diverse stars and their frequencies. As she compares her simulations to real stars, Goldstein can refine her model and improve how astrophysicists like her peer under the surface of stars by surveying their subtle sounds.


With frequencies repeating on the order of minutes to days, you’d have to speed up stellar vibrations by a thousand or a million times to bring them within the range of human hearing. These reverberations might most accurately be called starquakes after their seismic cousins on Earth. The field of study is called astroseismology.


As stars fuse hydrogen into heavier elements in their cores, hot plasma gas vibrates and causes stars to flicker. These fluctuations can tell researchers about a star’s structure and how it will change as the star ages. Goldstein studies stars that are larger than our own sun.


«Those are the ones that explode and make black holes and neutron stars and all the heavy elements in the universe that form planets and, essentially, new life,» says Goldstein. «We want to understand how they work and how they affect the evolution of the universe. So these really big questions.»



Working with astronomy professors Rich Townsend and Ellen Zweibel, Goldstein developed a program called GYRE that plugs into the star-simulating program MESA. Using this software, Goldstein constructs models of various kinds of stars to see what their vibrations might look like to astronomers. Then she checks how closely simulation and reality match.


«Since I made my stars, I know what I put inside of them. So when I compare my predicted vibration patterns against observed vibration patterns, if they’re the same, then great, the inside of my stars are like the insides of those real stars. If they’re different, which is usually the case, that gives us information that we need to improve our simulations and test again,» Goldstein says.


Both GYRE and MESA are open source programs, which means that scientists can freely access and modify the code. Each year, some 40 to 50 people attend a MESA summer school at the University of California, Santa Barbara to learn how to use the program and brainstorm improvements. Goldstein and her group benefit from all these users suggesting changes to and fixing errors in both MESA and their own program.


They also get a boost from another group of scientists—planet hunters. Two things can make a star’s brightness fluctuate: internal vibrations or a planet passing in front of the star. As the search for exoplanets—planets that orbit stars other than our own—has ramped up, Goldstein has gained access to a trove of new data on stellar fluctuations that are caught up in the same surveys of distant stars.


The latest exoplanet hunter is a telescope named TESS, which launched into orbit last year to survey 200,000 of the brightest, closest stars.


«What TESS is doing is looking at the entire sky,» says Goldstein. «So we’re going to be able to say for all the stars we can see in our neighborhood whether or not they’re pulsating. If they are, we’ll be able to study their pulsations to learn about what’s happening beneath the surface.»


Goldstein is now developing a new version of GYRE to take advantage of the TESS data. With it, she’ll start to simulate this stellar orchestra hundreds of thousands strong.


With these simulations, we might be able to glean a little more about our cosmic neighbors, just by listening in.


Author: Eric Hamilton | Source: University of Wisconsin-Madison [April 26, 2019]



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Geoscientists find new fallout from ‘the collision that changed the world’

When the landmass that is now the Indian subcontinent slammed into Asia about 50 million years ago, the collision changed the configuration of the continents, the landscape, global climate and more. Now a team of Princeton University scientists has identified one more effect: the oxygen in the world’s oceans increased, altering the conditions for life.











Geoscientists find new fallout from 'the collision that changed the world'
Neither the continents nor the oceans have always looked the way they do now. These “paleomaps” show how the
continents and oceans appeared before (top) and during (bottom) “the collision that changed the world,” when
the landmass that is now the Indian subcontinent rammed northward into Asia, closing the Tethys Sea and building
 the Himalayas. Global ocean levels were higher then, creating salty shallow seas (pale blue) that covered much
of North Africa and parts of each of the continents. A team of Princeton researchers, using samples gathered at
the three starred locations, created an unprecedented record of ocean nitrogen and oxygen levels from 70 million
years ago through 30 million years ago that shows a major shift in ocean chemistry after the India-Asia collision.
Another shift came 35 million years ago, when Antarctica began accumulating ice and global sea levels fell
[Credit: Images created by Emma Kast, Princeton University, using paleogeographic reconstructions
from Deep Time Maps, with their permission]

«These results are different from anything people have previously seen,» said Emma Kast, a graduate student in geosciences and the lead author on a paper published in Science. «The magnitude of the reconstructed change took us by surprise.»


Kast used microscopic seashells to create a record of ocean nitrogen over a period from 70 million years ago — shortly before the extinction of the dinosaurs — until 30 million years ago. This record is an enormous contribution to the field of global climate studies, said John Higgins, an associate professor of geosciences at Princeton and a co-author on the new Science paper.


«In our field, there are records that you look at as fundamental, that need to be explained by any sort of hypothesis that wants to make biogeochemical connections,» Higgins said. «Those are few and far between, in part because it’s very hard to create records that go far back in time. Fifty-million-year-old rocks don’t willingly give up their secrets. I would certainly consider Emma’s record to be one of those fundamental records. From now on, people who want to engage with how the Earth has changed over the last 70 million years will have to engage with Emma’s data.»


In addition to being the most abundant gas in the atmosphere, nitrogen is key to all life on Earth. «I study nitrogen so that I can study the global environment,» said Daniel Sigman, Princeton’s Dusenbury Professor of Geological and Geophysical Sciences and the senior author on the paper. Sigman initiated this project with Higgins and then-Princeton postdoctoral researcher Daniel Stolper, who is now an assistant professor of Earth and planetary science at the University of California-Berkeley.


Every organism on Earth requires «fixed» nitrogen — sometimes called «biologically available nitrogen.» Nitrogen makes up 78% of our planet’s atmosphere, but few organisms can «fix» it by converting the gas into a biologically useful form. In the oceans, cyanobacteria in surface waters fix nitrogen for all other ocean life. As the cyanobacteria and other creatures die and sink downward, they decompose.


Nitrogen has two stable isotopes, 15N and 14N. In oxygen-poor waters, decomposition uses up «fixed» nitrogen. This occurs with a slight preference for the lighter nitrogen isotope, 14N, so the ocean’s 15N-to-14N ratio reflects its oxygen levels.


That ratio is incorporated into tiny sea creatures called foraminifera during their lives, and then preserved in their shells when they die. By analyzing their fossils — collected by the Ocean Drilling Program from the North Atlantic, North Pacific, and South Atlantic — Kast and her colleagues were able to reconstruct the 15N-to-14N ratio of the ancient ocean, and therefore identify past changes in oxygen levels.


Oxygen controls the distribution of marine organisms, with oxygen-poor waters being bad for most ocean life. Many past climate warming events caused decreases in ocean oxygen that limited the habitats of sea creatures, from microscopic plankton to the fish and whales that feed on them. Scientists trying to predict the impact of current and future global warming have warned that low levels of ocean oxygen could decimate marine ecosystems, including important fish populations.


When the researchers assembled their unprecedented geologic record of ocean nitrogen, they found that in the 10 million years after dinosaurs went extinct, the 15N-to-14N ratio was high, suggesting that ocean oxygen levels were low. They first thought that the warm climate of the time was responsible, as oxygen is less soluble in warmer water. But the timing told another story: the change to higher ocean oxygen occurred around 55 million years ago, during a time of continuously warm climate.


«Contrary to our first expectations, global climate was not the primary cause of this change in ocean oxygen and nitrogen cycling,» Kast said. The more likely culprit? Plate tectonics. The collision of India with Asia — dubbed «the collision that changed the world» by legendary geoscientist Wally Broecker, a founder of modern climate research — closed off an ancient sea called the Tethys, disturbing the continental shelves and their connections with the open ocean.


«Over millions of years, tectonic changes have the potential to have massive effects on ocean circulation,» said Sigman. But that doesn’t mean climate change can be discounted, he added. «On timescales of years to millenia, climate has the upper hand.»


Author: Liz Fuller-Wright | Source: Princeton University [April 26, 2019]



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Sea serpent sightings influenced by ancient marine reptile fossil finds

Sea monster sightings in the 19th century were influenced by the discovery of ancient reptile fossils, new research at the University of St Andrews has discovered.











Sea serpent sightings influenced by ancient marine reptile fossil finds
Image of a sea serpent seen off Gloucester, Massachusetts in 1817
[Credit: University of St Andrews]

The idea that such reports were influenced by the first uncovering of Jurassic and Cretaceous sea reptiles was suggested in 1968 by science fiction author L Sprague De Camp.
De Camp, who wrote some of the later Conan the Barbarian stories, never tested his thesis but the mantle was taken up by St Andrews statistician Dr Charles Paxton.


Dr Paxton, of the School of Mathematics and Statistics at the University, teamed up with Dr Darren Naish, a palaeontologist at the University of Southampton, to use statistical analysis to find trends in sea monster reports from 1801 to 2015.











Sea serpent sightings influenced by ancient marine reptile fossil finds
Image of a sea monster seen off Greenland in 1743
[Credit: WikiCommons]

Published in the journal Earth Sciences History, the research found that De Camp’s theory was partially correct. Although the research team did not find an immediate change in the way monsters were described in the early 19th century, they did find evidence of a steady change.
Over the last two centuries they found evidence of a decline in serpent-like monster descriptions and an increase in the proportion of reports of monsters sighted with necks. This followed 19th century fossil discoveries such as that of Plesiosaurus which has a long neck.


Dr Paxton said: “The problem is an interesting fusion of history and palaeontology which shows that statistics can be used to rigorously test all sorts of strange hypotheses, if the data is handled in the right way.”











Sea serpent sightings influenced by ancient marine reptile fossil finds
Image of a sea sea serpent seen in the South Atlantic in 1848
[Credit: University of St Andrews]

In the autumn of 1848 British newspapers were gripped by the account of a sea serpent seen by the officers and crew of the HMS Daedalus in the South Atlantic the previous May.
In 1968 De Camp suggested that after Mesozoic reptiles became well-known reports of serpentine sea monsters became replaced with Mesozoic marine reptiles such as the plesiosaur or mosasaur.


The researchers created an electronic database of 1,688 historical reports, including books, newspaper accounts, and first-hand testimonies going back hundreds of years, of 1,543 sighting events omitting known hoaxes.











Sea serpent sightings influenced by ancient marine reptile fossil finds
A photograph supposedly taken by Robert Kenneth Wilson, a London gynaecologist,
which was published in the Daily Mail on 21 April 1934
[Credit: The Telegraph]

The reports include a peak between 1930 and 1934 of reports around the world following publicity associated with the Loch Ness monster in 1933.


Dr Paxton added: “The discovery of long-necked marine reptile fossils in the 19th century does appear to have had an influence on what people believe they have spotted in the water.”


Source: University of St Andrews [April 26, 2019]



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Ancient sculptures from Guatemala made from magnetized rocks struck by lightning

People living at least 2,000 years ago near the Pacific Coast of what’s now Guatemala crafted massive human sculptures with magnetized foreheads, cheeks and navels. New research provides the first detailed look at how these sculpted body parts were intentionally placed within magnetic fields on large rocks.











Ancient sculptures from Guatemala made from magnetized rocks struck by lightning
Ancient massive carvings from Guatemala such as this round figure include magnetized areas possibly
 intended to show the continuing power of deceased ancestors [Credit: ScienceNews]

Lightning strikes probably magnetized sections of boulders that were later carved into stylized, rotund figures — known as potbellies — at the Guatemalan site of Monte Alto, say Harvard University geoscientist Roger Fu and his colleagues.
Artisans may have held naturally magnetized mineral chunks near iron-rich, basalt boulders to find areas in the rock where magnetic forces pushed back, the scientists say in the Journal of Archaeological Science. Predesignated parts of potbelly figures — which can stand more than 2 meters tall and weigh 10,000 kilograms or more — were then carved at those spots.


Ancient sculptures from Guatemala made from magnetized rocks struck by lightning










Ancient sculptures from Guatemala made from magnetized rocks struck by lightning
Magnetic anomalies on ‘Potbellies’ at Monte Alto [Credit: Roger R.Fu et al. 2019]

Potbellies represented dead but still revered ancestors of high-ranking families, suspects art historian Julia Guernsey of the University of Texas at Austin. Sculptures that repelled magnetized objects would have been seen as demonstrating the presence and authority of deceased ancestors in rapidly expanding societies, she suggests. Fu’s results also indicate that Mesoamericans attributed special powers to certain body parts, such as the face and midsection, Guernsey adds.
The researchers studied 11 potbelly sculptures, six heads and five bodies, now displayed in a Guatemalan town. At least 127 such sculptures have been found at sites in Mesoamerica, an ancient cultural region that runs from central Mexico through much of Central America.


Handheld sensors confirmed a 1997 report that magnetic signals occurred over the right temple and cheek of three colossal heads from Monte Alto. Sensors also detected magnetism near the navels of four body sculptures. A portable, high-resolution magnetic sensor then precisely mapped magnetic fields on two head and two body sculptures.


Author: Bruce Bower | Source: ScienceNews [April 26, 2019]



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Tourmaline & Lepidolite | #Geology #GeologyPage…


Tourmaline & Lepidolite | #Geology #GeologyPage #Mineral


Locality: Pederneira Mine, Minas Gerais, Brazil


Size: 6.7 × 6.7 × 5 cm


Photo Copyright © Viamineralia /e-rocks. com


Geology Page

www.geologypage.com

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Prehistoric Gold Torcs, The British Museum, London, 20.4.19.

Prehistoric Gold Torcs, The British Museum, London, 20.4.19.












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Prehistoric Gold Neck Torc and Cloak Fasteners, The British Museum, London, 20.4.19.

Prehistoric Gold Neck Torc and Cloak Fasteners, The British Museum, London, 20.4.19.



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Remnants of Buddhist civilisation unearthed in Bangladesh

The recently excavated Nateshwar archaeological site bears witness to the Bengal region’s thousand-year-old history, with its pyramid-shaped stupas, wide walkways, mandaps and households. Ranging from biological remains of flora and fauna, to terracotta, metal and stone artefacts and unique architecture, the archaeological findings at Nateshwar paint the picture of an ancient civilisation that once flourished in Bangladesh.











Remnants of Buddhist civilisation unearthed in Bangladesh
Aerial view of the Nateshwar archaeological site
[Credit: The Daily Star]

After the remarkable feat of excavating the Wari-Bateshwar ruins, Dr Sufi Mustafizur Rahman, professor of archaeology at Jahangirnagar University, is the director of this project.


“The archaeological site of Nateshwar in Bikrampur has the potential to become a centre of Buddhist culture in South Asia, and earn its place as a world heritage site. From last December to March, we have conducted archaeological survey and excavation, discovering pyramid-shaped structures, and other important artefacts,” said Dr Sufi in a press briefing at Nateshwar excavation site in Munshiganj’s Tongibari upazila recently.


With support from the cultural affairs ministry and government’s archaeology division, this excavation and research project is being supervised by Bikrampur Foundation. The work began in 2010.


Dr Sufi mentioned, “In the years 2013-18, over 5,000 square metres of land was discovered. Last year, we excavated ancient residential structures in Ballalbari.” On the pyramid-like structure, Dr Sufi said, “This is a Buddhist stupa, akin to other stupas of this subcontinent such as Sanchi, Bharhut, Amaravati etc.”











Remnants of Buddhist civilisation unearthed in Bangladesh
Closer look at the ruins of the ancient stupas
[Credit: The Daily Star]

“Preliminary excavation was done in nine sites in the years 2010-13. We discovered six rooms where monks once lived, one mandap (worship pavilion), and pentagonal stupa in Rampal union. In 2013 at Nateshwar’s Deul area, we found a Buddhist temple, octagonal stupas, brick walkway and drains,” he added.


Keeping in mind the huge scale and scope of the preservation work, Bikrampur Foundation partnered up with the Institute of Cultural Relics and Archaeology in China’s Hunan province. “Through carbon dating, we have determined two timelines for the Buddhist residences – 780-950 AD for the first period and 950-1223 AD for the second,” said Dr Sufi.


There is a temple made of brick, three octagonal stupas with mandap, 51-metre long brick roads, multiple rooms and hall rooms, and entryway. Before the rainy season hits in full swing, the archaeological sites will be specially protected to prevent water from getting in, said Dr Sufi. He also announced the end of this phase of the excavation for the year.


State Minister for Cultural Affairs, KM Khalid said at the briefing, “These archaeological treasures must be preserved. Detailed research efforts will reveal the correct history of this site to enrich Bengali culture.”


Abdul Gani, a local teacher who visited the site, said, “This discovery has the potential to change the face of this area. These valuable artefacts must be protected at any cost.”


Authors: Farhana Mirza & Aanila Kishwar Tarannum | Source: The Daily Star [April 26, 2019]



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3,500-year-old petroglyphs found in Gansu, China

Archaeologist in Dahe town in Sunan county in Northwest China’s Gansu province discovered many ancient petroglyphs, including some in deer-shaped pattern, in the Yangkan Gorge and the Yumu Mountain in the Qilian Mountains on April 15.











3,500-year-old petroglyphs found in Gansu, China
Credit: Huang Minjiang/China Daily

The Yangkan Gorge, where the petroglyphs were found, is located with at an altitude of over 2,760 meters. The cultural relics professionals discovered six groups and 16 petroglyphs on the ground rock facing the southeast in the bottom of the valley. The paintings include deer, cattle, hunting patterns, etc., five of which are most prominent in the deer petroglyphs. With a length of 6 cm and a height of 8 cm, the largest one has a tall horns and a well-proportioned body and limbs, with four legs slightly bending. There is a sucking deer in the abdomen of the dear (the male and female reindeers both have horns), with a running-like deer in front of it.
Du Chengfeng, a member of the Chinese Rock Art Institution and the founder of the Qilian Mountain Rock Painting Studio, said, «The chiseling technique of these deer petroglyphs is to use the point-like chisel point to carry out the contour composition, and then the whole body is carved. It could be determined on the spot that the chiseling tool belongs to metal tools, which may be bronze tools or early iron tools. Using the attributes of chiseling tools combined with the prehistoric climate research of the Hexi Corridor and the living habits of deer, it was inferred that the deer paintings, with a history of 3,500 years, belongs to the Bronze Age or the early Iron Age.»











3,500-year-old petroglyphs found in Gansu, China
Credit: Huang Minjiang/China Daily

Most of petroglyphs of Yumu Mountain, located in the Qilian Mountains, are engraved on the lacquer slate and shale of the black Cambrian desert with relatively hard texture. Because of its high altitude, the vegetation is mainly xerophytic semi-shrub herbs, and there are a certain number of spruce, eucalyptus, sand jujube and shrub forests in the north of the valley.
Du said, «The deer in the rock painting is one of the animals witnessed by the ancestors. Different types of deer have a relatively preferred living environment and are highly depend on changing vegetation. Most of them live in tundra, forest areas, deserts, shrubs and swamps. Deer petroglyphs provide direct historical climate evidence not only for the calculation of approximate time of the deer living in the Hexi Corridor, but also for the research of ancient Qilian Mountain ecological environment and the living conditions of the herdsmen.»











3,500-year-old petroglyphs found in Gansu, China
Credit: Huang Minjiang/China Daily

Up to now, among the petroglyphs discovered in the Qilian Mountain, 86 pieces (nearly 5,000 petroglyphs) were found in the Yumu Mountain. Most of these petroglyphs are preserved intact, and most of the pictures are animal figures. The Yumu Mountain, the most concentrated range found in the Qilian Mountains, is also a rare open-air petroglyph museum.


Author: Huang Minjiang | Source: China Daily [April 26, 2019]



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What a dying star’s ashes tell us about the birth of our solar system

A grain of dust forged in the death throes of a long-gone star was discovered by a team of researchers led by the University of Arizona.











What a dying star's ashes tell us about the birth of our solar system
Billions of years ago, before our solar system was born, a dead star known as a white dwarf
in a nearby binary star system accumulated enough material from its companion to causeit to
 ‘go nova.’ The stellar explosion forged dust grains with exotic compositions not found in our
solar system. A team of researchers led by the UA found such a grain (inset image), encased in
a meteorite, that survived the formation of our solar system and analyzed it with instruments
 sensitive enough to ID single atoms in a sample. Measuring one 25,000th of an inch, the
 carbon-rich graphite grain (red) revealed an embedded speck of oxygen-rich material (blue),
two types of stardust that were thought could not form in the same nova eruption
[Credit: University of Arizona/Heather Roper]

The discovery challenges some of the current theories about how dying stars seed the universe with raw materials for the formation of planets and, ultimately, the precursor molecules of life.


Tucked inside a chondritic meteorite collected in Antarctica, the tiny speck represents actual stardust, most likely hurled into space by an exploding star before our own sun existed. Although such grains are believed to provide important raw materials contributing to the mix from which the sun and our planets formed, they rarely survive the turmoil that goes with the birth of a solar system.


«As actual dust from stars, such presolar grains give us insight into the building blocks from which our solar system formed,» said Pierre Haenecour, lead author of the paper, which is scheduled for advance online publication in Nature Astronomy. «They also provide us with a direct snapshot of the conditions in a star at the time when this grain was formed.»


Dubbed LAP-149, the dust grain represents the only known assemblage of graphite and silicate grains that can be traced to a specific type of stellar explosion called a nova. Remarkably, it survived the journey through interstellar space and traveled to the region that would become our solar system some 4.5 billion years ago, perhaps earlier, where it became embedded in a primitive meteorite.


Novae are binary star systems in which a core remnant of a star, called a white dwarf, is on its way to fading out of the universe, while its companion is either a low-mass main sequence star or a red giant. The white dwarf then begins syphoning material off its bloated companion. Once it accretes enough new stellar material, the white dwarf re-ignites in periodic outbursts violent enough to forge new chemical elements from the stellar fuel and spew them deep into space, where they can travel to new stellar systems and become incorporated in their raw materials.


Since shortly after the Big Bang, when the universe consisted of only hydrogen, helium and traces of lithium, stellar explosions have contributed to the chemical enrichment of the cosmos, resulting in the plethora of elements we see today.


Taking advantage of sophisticated ion and electron microscopy facilities at the UA’s Lunar and Planetary Laboratory, a research team led by Haenecour analyzed the microbe-sized dust grain down to the atomic level. The tiny messenger from outer space turned out to be truly alien — highly enriched in a carbon isotope called 13C.


«The carbon isotopic compositions in anything we have ever sampled that came from any planet or body in our solar system varies typically by a factor on the order of 50,» said Haenecour, who will join the Lunar and Planetary Laboratory as an assistant professor in the fall. «The 13C we found in LAP-149 is enriched more than 50,000-fold. These results provide further laboratory evidence that both carbon- and oxygen-rich grains from novae contributed to the building blocks of our solar system.»


Although their parent stars no longer exist, the isotopic and chemical compositions and microstructure of individual stardust grains identified in meteorites provide unique constraints on dust formation and thermodynamic conditions in stellar outflows, the authors wrote.


Detailed analysis revealed even more unexpected secrets: Unlike similar dust grains thought to have been forged in dying stars, LAP-149 is the first known grain consisting of graphite that contains an oxygen-rich silicate inclusion.


«Our find provides us with a glimpse into a process we could never witness on Earth,» Haenecour added. «It tells us about how dust grains form and move around inside as they are expelled by the nova. We now know that carbonaceous and silicate dust grains can form in the same nova ejecta, and they get transported across chemically distinct clumps of dust within the ejecta, something that was predicted by models of novae but never found in a specimen.»


Unfortunately, LAP-149 does not contain enough atoms to determine its exact age, so researchers hope to find similar, larger specimens in the future.


«If we could date these objects someday, we could get a better idea of what our galaxy looked like in our region and what triggered the formation of the solar system,» said Tom Zega, scientific director of the UA’s Kuiper Materials Imaging and Characterization Facility and associate professor in the Lunar and Planetary Laboratory and UA Department of Materials Science and Engineering. «Perhaps we owe our existence to a nearby supernova explosion, compressing clouds of gas and dust with its shockwave, igniting stars and creating stellar nurseries, similar to what we see in Hubble’s famous ‘Pillars of Creation’ picture.»


The meteorite containing the speck of stardust is one of the most pristine meteorites in the Lunar and Planetary Laboratory’s collection. Classified as a carbonaceous chondrite, it is believed to be analogous to the material on Bennu, the target asteroid of the UA-led OSIRIS-REx mission. By taking a sample of Bennu and bringing it back to Earth, the OSIRIS-REx mission team hopes to provide scientists with material that has seen little, if any, alteration since the formation of our solar system.


Until then, researchers depend on rare finds like LAP-149, which survived being blasted from an exploding star, caught in a collapsing cloud of gas and dust that would become our solar system and baked into an asteroid before falling to the earth.


«It’s remarkable when you think about all the ways along the way that should have killed this grain,» Zega said.


Source: University of Arizona [April 29, 2019]



TANN



Archive


Spinning black hole sprays light-speed plasma clouds into space

Astronomers have discovered rapidly swinging jets coming from a black hole almost 8000 light-years from Earth.











Spinning black hole sprays light-speed plasma clouds into space
Schematic artist’s impression of the changing jet orientation in V404 Cygni. Each segment
 (as separated by the clock hands) shows the jets at a different time, oriented in different
directions as seen in our high angular resolution radio imaging [Credit: ICRAR]

Published in the journal Nature, the research shows jets from V404 Cygni’s black hole behaving in a way never seen before on such short timescales.


The jets appear to be rapidly rotating with high-speed clouds of plasma—potentially just minutes apart—shooting out of the black hole in different directions.


Lead author Associate Professor James Miller-Jones, from the Curtin University node of the International Centre for Radio Astronomy Research (ICRAR), said black holes are some of the most extreme objects in the Universe.


«This is one of the most extraordinary black hole systems I’ve ever come across,» Associate Professor Miller-Jones said.


«Like many black holes, it’s feeding on a nearby star, pulling gas away from the star and forming a disk of material that encircles the black hole and spirals towards it under gravity.


«What’s different in V404 Cygni is that we think the disk of material and the black hole are misaligned. «This appears to be causing the inner part of the disk to wobble like a spinning top and fire jets out in different directions as it changes orientation.»


V404 Cygni was first identified as a black hole in 1989 when it released a big outburst of jets and radiation.


Astronomers looking at archival photographic plates then found previous outbursts in observations from 1938 and 1956.


Associate Professor Miller-Jones said that when V404 Cygni experienced another very bright outburst in 2015, lasting for two weeks, telescopes around the world tuned in to study what was going on.


«Everybody jumped on the outburst with whatever telescopes they could throw at it,» he said. «So we have this amazing observational coverage.»











Spinning black hole sprays light-speed plasma clouds into space
Artist’s impression of V404 Cygni seen close up. The binary star system consists of a normal star in orbit with a black hole.
Material from the star falls towards the black hole and spirals inwards in an accretion disk, with powerful jets being
launched from the inner regions close to the black hole [Credit: ICRAR]

When Associate Professor Miller-Jones and his team studied the black hole, they saw its jets behaving in a way never seen before.


Where jets are usually thought to shoot straight out from the poles of black holes, these jets were shooting out in different directions at different times.


And they were changing direction very quickly—over no more than a couple of hours.


Associate Professor Miller-Jones said the change in the movement of the jets was because of the accretion disk—the rotating disk of matter around a black hole.


He said V404 Cygni’s accretion disk is 10 million kilometres wide, and the inner few thousand kilometres was puffed up and wobbling during the bright outburst.


«The inner part of the accretion disk was precessing and effectively pulling the jets around with it,» Associate Professor Miller-Jones said.


«You can think of it like the wobble of a spinning top as it slows down—only in this case, the wobble is caused by Einstein’s theory of general relativity.»


The research used observations from the Very Long Baseline Array, a continent-sized radio telescope made up of 10 dishes across the United States, from the Virgin Islands in the Caribbean to Hawaii.


Co-author Alex Tetarenko—a recent PhD graduate from the University of Alberta and currently an East Asian Observatory Fellow working in Hawaii—said the speed the jets were changing direction meant the scientists had to use a very different approach to most radio observations.


«Typically, radio telescopes produce a single image from several hours of observation,» she said. «But these jets were changing so fast that in a four-hour image we just saw a blur.











Spinning black hole sprays light-speed plasma clouds into space
Artist’s impression of jet ejections in V404 Cygni. With our radio telescopes, we see individual bright clouds
of plasma that have been ejected from the innermost regions, and redirected by the puffed-up
 inner accretion disk [Credit: ICRAR]

«It was like trying to take a picture of a waterfall with a one-second shutter speed.» Instead, the researchers produced 103 individual images, each about 70 seconds long, and joined them together into a movie.


«It was only by doing this that we were able to see these changes over a very short time period,» Dr Tetarenko said.


Study co-author Dr Gemma Anderson, who is also based at ICRAR’s Curtin University node, said the wobble of the inner accretion disk could happen in other extreme events in the Universe too.


«Anytime you get a misalignment between the spin of a black hole and the material falling in, you would expect to see this when a black hole starts feeding very rapidly,» Dr Anderson said.


«That could include a whole bunch of other bright, explosive events in the Universe, such as supermassive black holes feeding very quickly or tidal disruption events, when a black hole shreds a star.»


Source: International Centre for Radio Astronomy Research [April 29, 2019]



TANN



Archive


GRACE mission data contributes to our understanding of climate change

The University of Texas at Austin team that led a twin satellite system launched in 2002 to take detailed measurements of the Earth, called the Gravity Recovery and Climate Experiment (GRACE), reports in the most recent issue of the journal Nature Climate Change on the contributions that their nearly two decades of data have made to our understanding of global climate patterns.











GRACE mission data contributes to our understanding of climate change
Global representation of trends and variability in ice and watermass recovered by GRACE over 15 years.
The top figure, which shows trend maps over Antarctica, Greenland and part of the Arctic, represent changes
 inice mass. The middle trend map mainly represents changes in the terrestrialwater storage, as well as large
 trends related to continental rebound after glacier ice-melts over continental areas, such as Alaska,
Patagonia and the Canadian Arctic.The trends of the terrestrial water storage are partially related floods
and droughts, but also reflect, for example, long term changes in groundwater depletion by human activity.
The bottom figure shows variability in the ocean bottom pressure and are particularly relevant for
understanding these effects in in the difficult to observed southern oceans and the Arctic Ocean.
For the first two, the red represents mass loss and blue represents mass gain. In last figure,
 the colour scales represent variability, with the highest variability shown in red
[Credit: Cockrell School Of Engineering, The University of Texas at Austin]

Among the many contributions that GRACE has made:


— GRACE recorded three times the mass of ice lost in the polar and mountainous regions since first beginning measurements — a consequence of global warming.


— GRACE enabled a measure of the quantity of heat added to the ocean and the location for said heat that remains stored in the ocean. GRACE has provided detailed observations, confirming that the majority of the warming occurs in the upper 2,000 meters of the oceans.


— GRACE has observed that of the 37 largest land-based aquifers, 13 have undergone critical mass loss. This loss, due to both a climate-related effect and an anthropogenic (human-induced) effect, documents the reduced availability of clean, fresh water supplies for human consumption.


— The information gathered from GRACE provides vital data for the federal agency United States Drought Monitor and has shed light on the causes of drought and aquifer depletion in places worldwide, from India to California.


Intended to last just five years in orbit for a limited, experimental mission to measure small changes in the Earth’s gravitational fields, GRACE operated for more than 15 years and has provided unprecedented insight into our global water resources, from more accurate measurements of polar ice loss to a better view of the ocean currents and the rise in global sea levels. The mission was a collaboration between NASA and the German Aerospace Centre and was led by researchers in the Center for Space Research in UT’s Cockrell School of Engineering.


By measuring changes in mass that cause deviations in the strength of gravity’s pull on the Earth’s various systems — water systems, ice sheets, atmosphere, land movements and more — the satellites can measure small changes in the Earth system interactions.


«By monitoring the physical components of the Earth’s dynamical system as a whole, GRACE provides a time variable and holistic overview of how our oceans, atmosphere and land surface topography interact,» said Byron Tapley, the Clare Cockrell Williams Centennial Chair Emeritus in the Department of Aerospace Engineering and Engineering Mechanics who established the Center for Space Research at UT in 1981 and who served as principal investigator of the GRACE mission.


The GRACE mission was selected as the first PI-led Earth System Pathfinder Mission, with Tapley and the Center for Space Research at the helm, and it was implemented under a collaboration with the NASA Jet Propulsion Laboratory and the German Geodetic Institute in Potsdam. The mission was implemented under a partnership between NASA and the German Space Agency, but UT faculty members, researchers and students made major contributions to the engineering, concept development and scientific data analysis components of the experiment. Despite being a risky venture operating on minimal funding, the GRACE mission surpassed all expectations and continues to provide a paradigm-shifting set of measurements.


«The concept of using the changing gravimetric patterns on Earth as a means to understanding major changes in the Earth system interactions had been proposed before,» Tapley said. «But we were the first to make it happen at a measurement level that supported the needs of the diverse Earth-science community.»


Now that the GRACE Follow-On mission, which the Center for Space Research will continue to play a role in, has launched successfully, the chance to continue the GRACE record for a second multidecadal measurement of changes in mass across the Earth system is possible. Engineers and scientists anticipate that the longer data interval will allow them to see an even clearer picture of how the planet’s climate patterns behave over time.


Source: University of Texas at Austin [April 29, 2019]



TANN



Archive


Rapid melting of the world’s largest ice shelf linked to solar heat in the ocean

An international team of scientists has found part of the world’s largest ice shelf is melting 10 times faster than the overall ice shelf average, due to solar heating of the surrounding ocean surface.











Rapid melting of the world's largest ice shelf linked to solar heat in the ocean
The Ross Polynya where solar heat is absorbed by the ocean. The vertical wall of the ice front
stretches a distance of 600 km [Credit: Poul Christoffersen]

In a study of Antarctica’s Ross Ice Shelf, which covers an area roughly the size of France, the scientists spent several years building up a record of how the north-west sector of this vast ice shelf interacts with the ocean beneath it. Their results, reported in the journal Nature Geoscience, show that the ice is melting much more rapidly than previously thought due to inflowing warm water.


«The stability of ice shelves is generally thought to be related to their exposure to warm deep ocean water, but we’ve found that solar heated surface water also plays a crucial role in melting ice shelves,» said first author Dr Craig Stewart from the National Institute of Water and Atmospheric Research (NIWA) in New Zealand, who conducted the work while a PhD student at the University of Cambridge.


Although the interactions between ice and ocean occurring hundreds of metres below the surface of ice shelves seem remote, they have a direct impact on long-term sea level. The Ross Ice Shelf stabilises the West Antarctic ice sheet by blocking the ice which flows into it from some of the world’s largest glaciers.


«Previous studies have shown that when ice shelves collapse, the feeding glaciers can speed up by a factor or two or three,» said co-author Dr Poul Christoffersen from Cambridge’s Scott Polar Research Institute. «The difference here is the sheer size of Ross Ice Shelf, which over one hundred times larger than the ice shelves we’ve already seen disappear.»


The team collected four years of data from an oceanographic mooring installed under the Ross Ice Shelf by collaborators at NIWA. Using instruments deployed through a 260 metre-deep borehole, the team measured temperature, salinity, melt rates and ocean currents in the cavity under the ice.


The team also used an extremely precise custom-made radar system to survey the changing thickness of the ice shelf. Supported by Antarctica New Zealand and the Rutherford Foundation’s Scott Centenary Scholarship at the Scott Polar Research Institute, Dr Stewart and Dr Christoffersen travelled more than 1000 km by snowmobile in order to measure ice thicknesses and map basal melt rates.











Rapid melting of the world's largest ice shelf linked to solar heat in the ocean
Cambridge and NIWA scientists traverse 1,000 km on the Ross Ice Shelf
[Credit: Poul Christoffersen]

Data from the instruments deployed on the mooring showed that solar heated surface water flows into the cavity under the ice shelf near Ross Island, causing melt rates to nearly triple during the summer months.


The melting is affected by a large area of open ocean in front of the ice shelf that is empty of sea ice due to strong offshore winds. This area, known as the Ross Sea Polynya, absorbs solar heat quickly in summer and this solar heat source is clearly influencing melting in the ice shelf cavity.


The findings suggest that conditions in the ice shelf cavity are more closely coupled with the surface ocean and atmosphere than previously assumed, implying that melt rates near the ice front will respond quickly to changes in the uppermost layer of the ocean.


«Climate change is likely to result in less sea ice, and higher surface ocean temperatures in the Ross Sea, suggesting that melt rates in this region will increase in the future,» said Stewart.


The potential for increasing melt rates in this region has implications for ice shelf stability due to the shape of the ice shelf. Rapid melting identified by the study happens beneath a thin and structurally important part of the ice shelf, where the ice pushes against Ross Island. Pressure from the island, transmitted through this region, slows the flow of the entire ice shelf.


«The observations we made at the front of the ice shelf have direct implications for many large glaciers that flow into the ice shelf, some as far as 900 km away,» said Christoffersen.


While the Ross Ice Shelf is considered to be releatively stable, the new findings show that it may be more vulnerable than thought so far. The point of vulnerability lies in the fact that that solar heated surface water flows into the cavity near a stabilising pinning point, which could be undermined if basal melting intensifies further.


The researchers point out that melting measured by the study does not imply that the ice shelf is currently unstable. The ice shelf has evolved over time and ice lost by melting due to inflow of warm water is roughly balanced by the inputs of ice from feeding glaciers and snow accumulation. This balance is, however, depending on the stability provided by the Ross Island pinning point, which the new study identifies as a point of future vulnerability.


Source: University of Cambridge [April 29, 2019]



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Archive


NASA Investigation Uncovers Cause of Two Science Mission Launch Failures


NASA — Launch Services Program (LSP) logo.


April 30, 2019



Image above: On Space Launch Complex 576-E at Vandenberg Air Force Base in California, Orbital Sciences workers monitor NASA’s Glory upper stack as a crane lifts it from a stationary rail for attachment to the Taurus XL rocket’s Stage 0. Image Credit: NASA.


NASA Launch Services Program (LSP) investigators have determined the technical root cause for the Taurus XL launch failures of NASA’s Orbiting Carbon Observatory (OCO) and Glory missions in 2009 and 2011, respectively: faulty materials provided by aluminum manufacturer, Sapa Profiles, Inc. (SPI).


LSP’s technical investigation led to the involvement of NASA’s Office of the Inspector General and the U.S. Department of Justice (DOJ). DOJ’s efforts, recently made public, resulted in the resolution of criminal charges and alleged civil claims against SPI, and its agreement to pay $46 million to the U.S. government and other commercial customers. This relates to a 19-year scheme that included falsifying thousands of certifications for aluminum extrusions to hundreds of customers.



This is an artist’s concept of the Orbiting Carbon Observatory. Image credits: NASA/JPL

NASA’s updated public summary of the launch failures, which was published Tuesday, comes after a multiyear technical investigation by LSP and updates the previous public summaries on the Taurus XL launch failures for the OCO and Glory missions. Those public summaries concluded that the launch vehicle fairing — a clamshell structure that encapsulates the satellite as it travels through the atmosphere — failed to separate on command, but no technical root cause had been identified. From NASA’s investigation, it is now known that SPI altered test results and provided false certifications to Orbital Sciences Corporation, the manufacturer of the Taurus XL, regarding the aluminum extrusions used in the payload fairing rail frangible joint. A frangible joint is a structural separation system that is initiated using ordnance.


“NASA relies on the integrity of our industry throughout the supply chain. While we do perform our own testing, NASA is not able to retest every single component. That is why we require and pay for certain components to be tested and certified by the supplier,” said Jim Norman, NASA’s director for Launch Services at NASA Headquarters in Washington. “When testing results are altered and certifications are provided falsely, missions fail. In our case, the Taurus XLs that failed for the OCO and Glory missions resulted in the loss of more than $700 million, and years of people’s scientific work. It is critical that we are able to trust our industry to produce, test and certify materials in accordance with the standards we require. In this case, our trust was severely violated.”



 Artist concept of Glory satellite. Image Credit: NASA

To protect the government supply chain, NASA suspended SPI from government contracting and proposed SPI for government-wide debarment. The exclusion from government contracting has been in effect since Sept. 30, 2015. NASA also has proposed debarment for Hydro Extrusion Portland, Inc.,formerly known as SPI,and the company currently is excluded from contracting throughout the federal government.


“Due in large part to the hard work and dedication of many highly motivated people in the NASA Launch Services program, we are able to close out the cause of two extremely disappointing launch vehicle failures and protect the government aerospace supply chain,” said Amanda Mitskevich, LSP program manager at NASA’s Kennedy Space Center in, Florida. “It has taken a long time to get here, involving years of investigation and testing, but as of today, it has been worth every minute, and I am extremely pleased with the entire team’s efforts.”


To learn more about NASA’s Launch Services Program, visit:


https://www.nasa.gov/centers/kennedy/launchingrockets/index.html


NASA Launch Services Program (LSP): https://elvperf.ksc.nasa.gov/Pages/Default.aspx


Orbiting Carbon Observatory (OCO): http://www.nasa.gov/mission_pages/oco/main/index.html


NASA’s Orbiting Carbon Observatory (OCO) failure: https://www.nasa.gov/mission_pages/oco/news/oco-20090717.html


Glory mission: https://www.nasa.gov/mission_pages/Glory/news/mishap-board-report.html


Images (mentioned), Text, Credits: NASA/Sean Potter/Gina Anderson.


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