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IceCube rules out last Standard Model explanation of ANITA's anomalous neutrino events – Tdnews

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IceCube rules out last Standard Model explanation of ANITA’s anomalous neutrino events

The IceCube Neutrino Observatory is possibly the strangest telescope on Earth. From its home at the South Pole, it sits and waits for fundamental particles called neutrinos to pass through its 5,160 optical detectors buried in the ice. When a neutrino interacts with a hydrogen or oxygen atom in the ice, it produces a signal that IceCube can detect.

But IceCube isn’t the only neutrino experiment in Antarctica. There is also the ANITA (the ANtarctic Impulsive Transient Antenna) experiment, which flies a balloon over the continent and points radio antennae toward the ground. ANITA searches for radio waves because extremely high-energy neutrinos—those hundreds of times more energetic than the ones that IceCube commonly detects—can produce intense radio signals when they smash into an atom in the ice.

From its balloon flights, ANITA claimed to have detected a few events that appear to be signals of these extremely high-energy neutrinos, so the IceCube Collaboration decided to investigate. In a paper submitted today to The Astrophysical Journal, they outline their search for an intense neutrino source in the direction of the events detected by ANITA. The collaboration found that these neutrinos could not have come from an intense point source. Other explanations for the anomalous signals—possibly involving exotic physics—need to be considered.

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When ANITA reported signals that looked like extremely high-energy neutrinos, physicists were puzzled. These neutrinos had arrived at an angle that suggested they had just traveled through most of the planet, which is not expected for neutrinos at these energies.

“It’s commonly said that neutrinos are ‘elusive’ or ‘ghostly’ particles because of their remarkable ability to pass through material without smashing into something,” says Alex Pizzuto of the University of Wisconsin–Madison, one of the leads on this paper. “But at these incredible energies, neutrinos are like bulls in a china shop—they become much more likely to interact with particles in Earth.”

Many scientists have since come up with potential explanations for these weird signals, and one possibility is that a really intense neutrino source produced them. After all, if a source produced huge numbers of neutrinos, it is more plausible that one or two made it to ANITA.

So Pizzuto and his collaborators decided to see whether there was an intense neutrino source shooting a beam of neutrinos toward Earth—a point source. To do this, the researchers took eight years of IceCube data and looked for correlations between the locations of the ANITA events and the locations of the IceCube events.

Since the researchers could not know how long a potential point source might have been emitting neutrinos, their analyses used three different and complementary approaches equipped to find coincidences on different timescales. Their analyses also had to account for uncertainty in the ANITA events’ directions because the events do not have definite positions on the sky.

Once they had addressed those challenges, the researchers simulated neutrinos passing through Earth to see how many incident neutrinos would be necessary for ANITA to see one event, and they then did the same for IceCube.

In all three searches, they found no evidence for a neutrino source in the direction of the strange ANITA events. This is particularly intriguing because, due to a process called tau neutrino regeneration, the extremely high-energy events that don’t make it all the way to ANITA should still be detectable by IceCube.

“This process makes IceCube a remarkable tool to follow up the ANITA observations, because for each anomalous event that ANITA detects, IceCube should have detected many, many more—which, in these cases, we didn’t,” says Anastasia Barbano of the University of Geneva in Switzerland, another lead on this paper. “That means that we can rule out the idea that these events came from some intense point source, because the odds of ANITA seeing an event and IceCube not seeing anything are so slim.”

When the ANITA events were detected, the main hypotheses were an astrophysical explanation (like an intense neutrino source), a systematics error (like not accounting for something in the detector), or physics beyond the Standard Model. “Our analysis ruled out the only remaining Standard Model astrophysical explanation of the anomalous ANITA events,” says Pizzuto. “So now, if these events are real and not just due to oddities in the detector, then they could be pointing to physics beyond the Standard Model.”

Ibrahim Safa of UW–Madison, another lead on this paper, says that while it has been an exciting time for physicists trying to explain these events, “it looks like we’ll have to wait for the next generation of experiments, which will increase exposure and sensitivity, to get a clear understanding of this anomaly.”

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Biosignatures: Discovery Of Earth’s Oldest DNA Breaks Record By One Million Years

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Taxonomic profiles of the plant assemblage found in the metagenomes. Taxa in bold are genera only found as DNA and not as macrofossil or pollen. Asterisks indicate those that are found at other Pliocene Arctic sites. Extinct species as identified by either macrofossils or phylogenetic placements are marked with a dagger. Reads classified as Pyrus and Malus are marked with a pound symbol, and are probably over-classified DNA sequences belonging to another species within Rosaceae that are not present as a reference genome. — University of Cambridge

Two-million-year-old DNA has been identified for the first time – opening a ‘game-changing’ new chapter in the history of evolution.

 

Microscopic fragments of environmental DNA were found in Ice Age sediment in northern Greenland. Using cutting-edge technology, researchers discovered the fragments are one million years older than the previous record for DNA sampled from a Siberian mammoth bone.

The ancient DNA has been used to map a two-million-year-old ecosystem which weathered extreme climate change. Researchers hope the results could help to predict the long-term environmental toll of today’s global warming.

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The discovery was made by a team of scientists led by Professor Eske Willerslev and Professor Kurt H. Kjær. Professor Willerslev is a Fellow of St John’s College, University of Cambridge, and Director of the Lundbeck Foundation GeoGenetics Centre at the University of Copenhagen where Professor Kjær, a geology expert, is also based.

The results of the 41 usable samples found hidden in clay and quartz are published today (7 DECEMBER 2022) in Nature.

Professor Willerslev said: “A new chapter spanning one million extra years of history has finally been opened and for the first time we can look directly at the DNA of a past ecosystem that far back in time..

“DNA can degrade quickly but we’ve shown that under the right circumstances, we can now go back further in time than anyone could have dared imagine.”

Professor Kjær said: “The ancient DNA samples were found buried deep in sediment that had built-up over 20,000 years. The sediment was eventually preserved in ice or permafrost and, crucially, not disturbed by humans for two million years.”

The incomplete samples, a few millionths of a millimetre long, were taken from the København Formation, a sediment deposit almost 100 metres thick tucked in the mouth of a fjord in the Arctic Ocean in Greenland’s northernmost point. The climate in Greenland at the time varied between Arctic and temperate and was between 10-17C warmer than Greenland is today. The sediment built up metre by metre in a shallow bay.

Scientists discovered evidence of animals, plants and microorganisms including reindeer, hares, lemmings, birch and poplar trees. Researchers even found that Mastodon, an Ice Age mammal, roamed as far as Greenland before later becoming extinct. Previously it was thought the range of the elephant-like animals did not extend as far as Greenland from its known origins of North and Central America.

Detective work by 40 researchers from Denmark, the UK, France, Sweden, Norway, the USA and Germany, unlocked the secrets of the fragments of DNA. The process was painstaking – first they needed to establish whether there was DNA hidden in the clay and quartz, and if there was, could they successfully detach the DNA from the sediment to examine it? The answer, eventually, was yes. The researchers compared every single DNA fragment with extensive libraries of DNA collected from present-day animals, plants and microorganisms. A picture began to emerge of the DNA from trees, bushes, birds, animals and microorganisms.

Some of the DNA fragments were easy to classify as predecessors to present-day species, others could only be linked at genus level, and some originated from species impossible to place in the DNA libraries of animals, plants and microorganisms still living in the 21st century.

The two-million-year-old samples also help academics build a picture of a previously unknown stage in the evolution of the DNA of a range of species still in existence today.

Professor Kjær said: “Expeditions are expensive and many of the samples were taken back in 2006 when the team were in Greenland for another project, they have been stored ever since.

“It wasn’t until a new generation of DNA extraction and sequencing equipment was developed that we’ve been able to locate and identify extremely small and damaged fragments of DNA in the sediment samples. It meant we were finally able to map a two-million-year-old ecosystem.”

Assistant Professor Mikkel W. Pedersen, co-first author on the paper and also based at the Lundbeck Foundation GeoGenetics Centre, said: “The Kap København ecosystem, which has no present-day equivalent, existed at considerably higher temperatures than we have today – and because, on the face of it, the climate seems to have been similar to the climate we expect on our planet in the future due to global warming.

“One of the key factors here is to what degree species will be able to adapt to the change in conditions arising from a significant increase in temperature. The data suggests that more species can evolve and adapt to wildly varying temperatures than previously thought. But, crucially, these results show they need time to do this. The speed of today’s global warming means organisms and species do not have that time so the climate emergency remains a huge threat to biodiversity and the world – extinction is on the horizon for some species including plants and trees.”

While reviewing the ancient DNA from the Kap København Formation, the researchers also found DNA from a wide range of microorganisms, including bacteria and fungi, which they are continuing to map. A detailed description of how the interaction – between animals, plants and single-cell organisms – within the former ecosystem at Greenland’s northernmost point worked biologically will be presented in a future research paper.

It is now hoped that some of the ‘tricks’ of the two-million-year-old plant DNA discovered may be used to help make some endangered species more resistant to a warming climate.

Professor Kjær said: “It is possible that genetic engineering could mimic the strategy developed by plants and trees two million years ago to survive in a climate characterised by rising temperatures and prevent the extinction of some species, plants and trees. This is one of the reasons this scientific advance is so significant because it could reveal how to attempt to counteract the devastating impact of global warming.”

The findings from the Kap København Formation in Greenland have opened up a whole new period in DNA detection.

Professor Willerslev explained: “DNA generally survives best in cold, dry conditions such as those that prevailed during most of the period since the material was deposited at Kap København. Now that we have successfully extracted ancient DNA from clay and quartz, it may be possible that clay may have preserved ancient DNA in warm, humid environments in sites found in Africa.

“If we can begin to explore ancient DNA in clay grains from Africa, we may be able to gather ground-breaking information about the origin of many different species – perhaps even new knowledge about the first humans and their ancestors – the possibilities are endless.”

 

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How you can watch Mars disappear behind the full moon tonight

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If you happen to have clear skies on Wednesday night, you’ll be able to catch a planet disappearing behind the moon.

The event occurs at a special time for Mars. On Wednesday night, Mars will be directly opposite the sun’s position in the sky, rising as the sun sets and setting as the sun rises. This is called an opposition and is when Mars is at its brightest in the night sky.

“Having the moon hide a bright planet is rare,” said Alan Dyer, an amateur astronomer and accomplished astrophotographer who will watch the event from his home near Strathmore, Alta.

“Having it do so on the very night a planet is at its brightest, as Mars now is, is very unusual. And with the objects so well-placed high in our sky. Fabulous!”

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When a planet or a star disappears behind another object, it’s called an occultation. The next time this happens between the moon and Mars will be in January 2025, although it will be two days before opposition.

When and where to look

Canada is in a prime location for the event.

Elaina Hyde, director of the Allan I. Carswell Observatory at York University’s department of physics and astronomy in Toronto, is also looking forward to Wednesday night’s occultation.

“Tonight, the occultation of Mars by our moon requires a ‘just right’ alignment,” she said. “In fact, not everyone on Earth will even be able to see this one.”

If you want to watch Mars blink out behind the moon, you just need clear skies. However, binoculars will provide a better view (though, be warned: a full moon is quite bright with binoculars or a telescope).

Because the occultation is between the moon, which is super bright, and Mars, which is at its brightest, they’re easy to find.

All you have to do is look east to find the moon. Mars will appear at the left or lower left, depending on your location.

People across North America in the shaded areas on the map will enjoy the the sight of the moon eclipsing Mars on Wednesday night. (Gregg Dinderman/Sky & Telescope)

You can gradually watch the event unfold right after sunset, when the pair will be farther apart. Over the next few hours, the pair will gradually appear to get closer and closer. The moon will seem to move to the left as they rise in the sky, eventually overtaking Mars.

How long Mars will stay eclipsed behind the moon depends on your location: it could be several minutes or about an hour. This is because it depends on how much of the moon’s disc Mars will need to traverse.

For example, in Toronto, Mars will only cross a small fraction of the moon’s lower disc, beginning at 10:29 p.m. ET and re-emerging roughly 45 minutes later. In Edmonton, it will take more than an hour for the entire event.

Here are the approximate times when Mars will disappear behind the moon. All times are local:

  • Vancouver: 6:55 p.m.
  • Edmonton: 8:04 p.m.
  • Calgary: 7:59 p.m.
  • Regina: 9:01 p.m.
  • Saskatoon: 9:03 p.m.
  • Winnipeg: 9:05 p.m.
  • Toronto: 10:29 p.m.
  • Ottawa: 10:36 p.m.
  • Montreal: 10:40 p.m.
  • Iqaluit: 9:50 p.m.
  • Whitehorse: 8:25 p.m.
  • Yellowknife: 8:23 p.m.

Thursday:

  • Halifax: 12:15 a.m.
  • Charlottetown: 12:07 a.m.
  • Moncton: 12:04 a.m.
  • St. John’s: 12:25 a.m.

You can find more locations here.

Remember, the event occurs all night, so you can take a peek outside once in a while leading up to the occultation and afterwards as it progresses.

You may also notice a bright red star not too far away from the moon and Mars, but to the right. That’s Aldebaran, the brightest star in the constellation Taurus.

This red giant lies near one of the most beautiful open star clusters in the northern sky, Hyades. In a few days’ time, once the moon moves away from that area of the sky, try using a pair of binoculars to check out the cluster.

Also, since you’re outside on Wednesday night, why not take a peak to the southwest where Jupiter will be quite apparent as the brightest object in the sky (aside from the moon). A pair of binoculars will also reveal four of its brightest moons, Io, Callisto, Ganymede and Europa.

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World’s oldest DNA has been found

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NEW YORK –

Scientists discovered the oldest known DNA and used it to reveal what life was like 2 million years ago in the northern tip of Greenland. Today, it’s a barren Arctic desert, but back then it was a lush landscape of trees and vegetation with an array of animals, even the now extinct mastodon.

“The study opens the door into a past that has basically been lost,” said lead author Kurt Kjaer, a geologist and glacier expert at the University of Copenhagen.

With animal fossils hard to come by, the researchers extracted environmental DNA, also known as eDNA, from soil samples. This is the genetic material that organisms shed into their surroundings — for example, through hair, waste, spit or decomposing carcasses.

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Studying really old DNA can be a challenge because the genetic material breaks down over time, leaving scientists with only tiny fragments.

But with the latest technology, researchers were able to get genetic information out of the small, damaged bits of DNA, explained senior author Eske Willerslev, a geneticist at the University of Cambridge. In their study, published Wednesday in the journal Nature, they compared the DNA to that of different species, looking for matches.

The samples came from a sediment deposit called the Kap Kebenhavn formation in Peary Land. Today, the area is a polar desert, Kjaer said.

But millions of years ago, this region was undergoing a period of intense climate change that sent temperatures up, Willerslev said. Sediment likely built up for tens of thousands of years at the site before the climate cooled and cemented the finds into permafrost.

The cold environment would help preserve the delicate bits of DNA — until scientists came along and drilled the samples out, beginning in 2006.

During the region’s warm period, when average temperatures were 11 to 19 degrees Celsius higher than today, the area was filled with an unusual array of plant and animal life, the researchers reported. The DNA fragments suggest a mix of Arctic plants, like birch trees and willow shrubs, with ones that usually prefer warmer climates, like firs and cedars.

The DNA also showed traces of animals including geese, hares, reindeer and lemmings. Previously, a dung beetle and some hare remains had been the only signs of animal life at the site, Willerslev said.

One big surprise was finding DNA from the mastodon, an extinct species that looks like a mix between an elephant and a mammoth, Kjaer said.

Many mastodon fossils have previously been found from temperate forests in North America. That’s an ocean away from Greenland, and much farther south, Willerslev said.

“I wouldn’t have, in a million years, expected to find mastodons in northern Greenland,” said Love Dalen, a researcher in evolutionary genomics at Stockholm University who was not involved in the study.

Because the sediment built up in the mouth of a fjord, researchers were also able to get clues about marine life from this time period. The DNA suggests horseshoe crabs and green algae lived in the area — meaning the nearby waters were likely much warmer back then, Kjaer said.

By pulling dozens of species out of just a few sediment samples, the study highlights some of eDNA’s advantages, said Benjamin Vernot, an ancient DNA researcher at Germany’s Max Planck Institute for Evolutionary Anthropology who was not involved in the study.

“You really get a broader picture of the ecosystem at a particular time,” Vernot said. “You don’t have to go and find this piece of wood to study this plant, and this bone to study this mammoth.”

Based on the data available, it’s hard to say for sure whether these species truly lived side by side, or if the DNA was mixed together from different parts of the landscape, said Laura Epp, an eDNA expert at Germany’s University of Konstanz who was not involved in the study.

But Epp said this kind of DNA research is valuable to show “hidden diversity” in ancient landscapes.

Willerslev believes that because these plants and animals survived during a time of dramatic climate change, their DNA could offer a “genetic roadmap” to help us adapt to current warming.

Stockholm University’s Dalen expects ancient DNA research to keep pushing deeper into the past. He worked on the study that previously held the “oldest DNA” record, from a mammoth tooth around a million years old.

“I wouldn’t be surprised if you can go at least one or perhaps a few million years further back, assuming you can find the right samples,” Dalen said.

——

The Associated Press Health and Science Department receives support from the Howard Hughes Medical Institute’s Science and Educational Media Group. The AP is solely responsible for all content.

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