Different models have been proposed to elucidate the origins of the founding populations of America, along with the number of migratory waves and routes used by these first explorers. Settlements, both along the Pacific coast and on land, have been evidenced in genetic and archeological studies. However, the number of migratory waves and the origin of immigrants are still controversial topics. Here, we show the Australasian genetic signal is present in the Pacific coast region, indicating a more widespread signal distribution within South America and implicating an ancient contact between Pacific and Amazonian dwellers. We demonstrate that the Australasian population contribution was introduced in South America through the Pacific coastal route before the formation of the Amazonian branch, likely in the ancient coastal Pacific/Amazonian population. In addition, we detected a significant amount of interpopulation and intrapopulation variation in this genetic signal in South America. This study elucidates the genetic relationships of different ancestral components in the initial settlement of South America and proposes that the migratory route used by migrants who carried the Australasian ancestry led to the absence of this signal in the populations of Central and North America.

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Yesterday was like a good TV episode: high-speed action, plot twists, and a cliffhanger ending. We now know that the strength of the little magnet inside the muon is described by the g-factor: 

g = 2.00233184122(82).

Any measurement of basic properties of matter is priceless, especially when it come with this incredible precision.  But for a particle physicist the main source of excitement is that this result could herald the breakdown of the Standard Model. The point is that the g-factor or the magnetic moment of an elementary particle can be calculated theoretically to a very good accuracy. Last year, the white paper of the Muon g−2 Theory Initiative came up with the consensus value for the Standard Model prediction                                                                    g = 2.00233183620(86)

which is significantly smaller than the experimental value.  The discrepancy is estimated at 4.2 sigma, assuming the theoretical error is Gaussian and combining the errors in quadrature. 

As usual, when we see an experiment and the Standard Model disagree, these 3 things come to mind first

  1.  Statistical fluctuation. 

  2.  Flawed theory prediction. 

  3.  Experimental screw-up.   

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The multicolor, stereo imaging Mastcam-Z on the Perseverance rover zoomed in to captured this 3D close-up (get out your red/blue glasses) of the Mars Ingenuity helicopter on mission sol 45, April 5. That’s only a few sols before the technology demonstrating Ingenuity will attempt to fly in the thin martian atmosphere, making the first powered flight on another planet. The historic test flight is planned for no earlier than Sunday, April 11. Casting its shadow on the martian surface, Ingenuity is standing alone on four landing legs next to the rover’s wheel tracks. The experimental helicopter’s solar panel, charging batteries that keep it warm through the cold martian nights and power its flight, sits above its two 1.2 meter (4 foot) long counter-rotating blades.

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Today’s long-anticipated announcement by Fermilab’s Muon g-2 team appears to solidify a tantalizing conflict between nature and theory. But a separate calculation, published at the same time, has clouded the picture.

This paper explores the fundamental causal limits on how much of the universe we can observe or affect. It distinguishes four principal regions: the affectable universe, the observable universe, the eventually observable universe, and the ultimately observable universe. It then shows how these (and other) causal limits set physical bounds on what spacefaring civilisations could achieve over the longterm future.

When the brain forms a memory of a new experience, neurons called engram cells encode the details of the memory and are later reactivated whenever we recall it. A new MIT study reveals that this process is controlled by large-scale remodeling of cells’ chromatin.

This remodeling, which allows specific genes involved in storing memories to become more active, takes place in multiple stages spread out over several days. Changes to the density and arrangement of chromatin, a highly compressed structure consisting of DNA and proteins called histones, can control how active specific genes are within a given cell.

“This paper is the first to really reveal this very mysterious process of how different waves of genes become activated, and what is the epigenetic mechanism underlying these different waves of gene expression,” says Li-Huei Tsai, the director of MIT’s Picower Institute for Learning and Memory and the senior author of the study.

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Israeli researchers studying the nutrition of Stone Age humans say the species spent some 2 million years as hyper-carnivorous “apex predators” that ate mostly the meat of large animals.

The study at Tel Aviv University, in collaboration with Portugal’s University of Minho, challenges views that prehistoric humans were omnivores and that their eating habits can be compared to those of modern humans, TAU said in a statement.

About 15 million years after the big bang, the entire universe had cooled to the point where the electromagnetic radiation left over from its hot beginning was at about room temperature. In a 2013 paper, I labeled this phase as the “habitable epoch of the early universe.” If we had lived at that time, we wouldn’t have needed the sun to keep us warm; that cosmic radiation background would have sufficed.

Did life start that early? Probably not. The hot, dense conditions in the first 20 minutes after the big bang produced only hydrogen and helium along with a tiny trace of lithium (one in 10 billion atoms) and a negligible abundance of heavier elements. But life as we know it requires water and organic compounds, whose existence had to wait until the first stars fused hydrogen and helium into oxygen and carbon in their interiors about 50 million years later. The initial bottleneck for life was not a suitable temperature, as it is today, but rather the production of the essential elements.

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Research published today in the peer-reviewed Journal of Vertebrate Paleontology describes a newly discovered species of dinosaur—named the ‘one who causes fear’, or Llukalkan aliocranianus.

Around 80 million years ago as tyrannosaurs ruled the Northern Hemisphere, this lookalike was one of 10 currently known species of abelisaurids flourishing in the southern continents.

A fearsome killer, Llukalkan was “likely among the top predators” throughout Patagonia, now in Argentina, during the Late Cretaceous due to its formidable size (up to five meters long), extremely powerful bite, very sharp teeth, huge claws in their feet and their keen sense of smell.

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Adeta bir bilim kurgu malzemesi olan antimadde ya da karşıt madde popüler kültürün mihenk taşıdır! Antimaddeyle Dan Brown’nın Melekler ve Şeytanlar adlı kitabında Robert Langdon’ın Vatikanı bir antimadde bombasından kurtarma girişimi esnasında karşılaşıyoruz. Daha sonra Star Trek’in yıldız gemisi Enterprise’ın (Atılgan) daha hızlı hareket edebilmesi için warp motorunun antimadde ile çalışıyor olması ve daha niceleri sanat ve kültür mecrasına derinlemesine işlemiş bir antimadde furyasına işaret ediyor. Peki bu herkesin dilinden düşmeyen antimadde nedir? Bu sorunun cevabını vermek için öncelikle madde nedir onu tanıyalım.

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A team of scientists at Arizona State University has proposed that the large blobs of material in Earth’s mantle (the large low-shear velocity provinces, LLSVPs) may be left over pieces of Theia, a protoplanet theorized to have struck Earth, resulting in the creation of the moon. The group argued their case at this year’s Lunar and Planetary Science Conference and are awaiting publication in Geophysical Research Letters.

As the team led by Prof. Tajmar reported last weekend at the “Space Propulsion Conference 2020 + 1” (which was postponed due to the Corona pandemic) and published in three accompanying papers in the “Proceedings of Space Propulsion Conference 2020 + 1” (Paper 1, Paper 2, Paper 3), they had to confirm the previously discussed interim results, according to which the EmDrive does not develop the thrust previously observed by other teams (such as NASA’s Eagleworks and others). The team also confirmed that the already measured thrust forces can be explained by external effects, as they have now been proven by Tajmar and colleagues using a highly sensitive experimental and measurement setup.

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Octopuses have alternating periods of “quiet” and “active” sleep that make their rest similar to that of mammals, despite being separated by more than 500 million years of evolution.

During their active periods of sleep, octopuses’ skin color changes and their bodies twitch, according to a report in the journal iScience, and they might even have short dreams.

“If they are dreaming, they are dreaming for up to a minute,” says Sidarta Ribeiro, a neuroscientist at the Brain Institute at the Federal University of Rio Grande do Norte in Brazil.

It’s been clear for awhile that octopuses can change color as they sleep; videos of this have even gone viral. And previously, other groups had suggested that cuttlefish have an active sleep state similar to the rapid eye movement (REM) sleep seen in birds, mammals and some reptiles.

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A team of scientists at Arizona State University has proposed that the large blobs of material in Earth’s mantle (the large low-shear velocity provinces, LLSVPs) may be left over pieces of Theia, a protoplanet theorized to have struck Earth, resulting in the creation of the moon. The group argued their case at this year’s Lunar and Planetary Science Conference and are awaiting publication in Geophysical Research Letters.

Most space scientists have come to believe that the moon was created when another planet (now called Theia) collided with a very early Earth—pieces of Earth, Theia or both that were flung into space during the collision eventually coalesced into the moon. Theories regarding what happened to the rest of Theia are still being argued. In this new effort, the team in Arizona suggests that much of Theia’s mantle wound up in Earth’s mantle, forming what are now called the large low-shear-velocity provinces, LLSVPs—one beneath parts of the African continent and one beneath the Pacific Ocean.

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Horses seem to recognise themselves in mirrors, and they may even use the information in their reflection to recognise if their face is dirty and needs wiping clean.

Eleven horses out of a group of 14 tried to rub coloured marks off their own cheeks after they discovered them in a mirror. This makes horses the only animals besides primates found to be generally capable of self-recognition in a mirror, says Paolo Baragli at the University of Pisa in Italy.

Greenland sharks are now the longest-living vertebrates known on Earth, scientists say.

Researchers used radiocarbon dating to determine the ages of 28 of the animals, and estimated that one female was about 400 years old.

The team found that the sharks grow at just 1cm a year, and reach sexual maturity at about the age of 150.

The research is published in the journal Science.

Lead author Julius Nielsen, a marine biologist from the University of Copenhagen, said: “We had our expectations that we were dealing with an unusual animal, but I think everyone doing this research was very surprised to learn the sharks were as old as they were.”

The former vertebrate record-holder was a bowhead whale estimated to be 211 years old.

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Generally thought of as fierce horse warriors, the Scythians were a multitude of Iron Age cultures who ruled the Eurasian steppe, playing a major role in Eurasian history. A new study published in Science Advances analyzes genome-wide data for 111 ancient individuals spanning the Central Asian Steppe from the first millennia BCE and CE. The results reveal new insights into the genetic events associated with the origins, development and decline of the steppe’s legendary Scythians.

Because of their interactions and conflicts with the major contemporaneous civilizations of Eurasia, the Scythians enjoy a legendary status in historiography and popular culture. The Scythians had major influences on the cultures of their powerful neighbors, spreading new technologies such as saddles and other improvements for horse riding. The ancient Greek, Roman, Persian and Chinese empires all left a multitude of sources describing, from their perspectives, the customs and practices of the feared horse warriors that came from the interior lands of Eurasia.

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A pernicious agricultural pest owes some of its success to a gene pilfered from its plant host millions of years ago.

The finding, reported today in Cell1, is the first known example of a natural gene transfer from a plant to an insect. It also explains one reason why the whitefly Bemisia tabaci is so adept at munching on crops: the gene that it swiped from plants enables it to neutralize a toxin that some plants produce to defend against insects.

Early work suggests that inhibiting this gene can render the whiteflies vulnerable to the toxin, providing a potential route to combating the pest. “This exposes a mechanism through which we can tip the scales back in the plant’s favour,” says Andrew Gloss, who studies plant–pest interactions at the University of Chicago in Illinois. “It’s a remarkable example of how studying evolution can inform new approaches for applications like crop protection.”

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Humans are the only species that can throw well enough to kill rivals and prey. Because throwing requires the highly coordinated and extraordinarily rapid movements of multiple body parts, there was likely a long history of selection favoring the evolution of expert throwing in our ancestors.

Most people probably don’t think throwing is important outside of sports because they’ve forgotten its usefulness. Part of that has to do with the fact that people have been using weapons like bows and firearms for centuries.

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Scientists believe they may have discovered a “brand-new force of nature” at CERN’s Large Hadron Collider that could explain why certain atomic particles behave unexpectedly and which may transform our understanding the rudiments of physics.

Authors of the research said this week that their results should “get physicists’ hearts beating just a little faster” after they discovered evidence of a “brand-new” type of particle.

Buried beneath 20 kilometers of ice, the subsurface ocean of Enceladus—one of Saturn’s moons—appears to be churning with currents akin to those on Earth.

The theory, derived from the shape of Enceladus’s ice shell, challenges the current thinking that the moon’s global ocean is homogenous, apart from some vertical mixing driven by the warmth of the moon’s core.

Enceladus, a tiny frozen ball about 500 kilometers in diameter (about 1/7th the diameter of Earth’s moon), is the sixth largest moon of Saturn. Despite its small size, Enceladus attracted the attention of scientists in 2014 when a flyby of the Cassini spacecraft discovered evidence of its large subsurface ocean and sampled water from geyser-like eruptions that occur through fissures in the ice at the south pole. It is one of the few locations in the solar system with liquid water (another is Jupiter’s moon Europa), making it a target of interest for astrobiologists searching for signs of life.

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Scientists found frozen plant fossils, preserved under a mile of ice on Greenland. The discovery helps confirm a new and troubling understanding that the Greenland Ice Sheet has melted entirely during recent warm periods in Earth’s history – like the one we are now creating with human-caused climate change. The new study provides strong evidence that Greenland is more sensitive to climate change than previously understood – and at risk of irreversibly melting.

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Created on Jun 17, 2020
By @gurlic
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