Carbon dating was developed from about 1950 and the first assumption was that the air always contained a constant amount of carbon dioxide with a radioactive C14 atom. However C14 is produced when a Nitrogen atom absorbs a slow neutron from cosmic radiation and ejects a proton and the flux of cosmic radiation depends on the activity of the Sun. So as far as possible radiocarbon dates are calibrated against known dates, for example from counted tree rings from trees found in bogs.
What the Heck?! Thread (Closed)
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broadsword
Brigadier
Vigilante justice done right. No need for lynching.
Miragedriver
Brigadier
60,000 Antelopes Died in 4 Days — And No One Knows Why
It started in late May.
When geoecologist Steffen Zuther and his colleagues arrived in central Kazakhstan to monitor the calving of one herd of saigas, a , steppe-dwelling antelope, veterinarians in the area had already reported dead animals on the ground.
"But since there happened to be die-offs of limited extent during the last years, at first we were not really alarmed," Zuther, the international coordinator of the Altyn Dala Conservation Initiative, told Live Science.
But within four days, the entire herd — 60,000 — had died. As veterinarians and conservationists tried to stem the die-off, they also got word of similar population crashes in other herds across Kazakhstan. By early June, the mass dying was over. []
Now, the researchers have found clues as to how more than half of the country's herd, counted at 257,000 as of 2014, died so rapidly. Bacteria clearly played a role in the saigas' demise. But exactly how these normally harmless microbes could take such a toll is still a mystery, Zuther said.
"The extent of this die-off, and the speed it had, by spreading throughout the whole calving herd and killing all the animals, this has not been observed for any other species," Zuther said. "It's really unheard of."
Crucial steppe players
Saigas play a critical role in the ecosystem of the arid grassland steppe, where the cold winters prevent fallen plant material from decomposing; the grazing of the dog-size, Gonzo-nosed antelopes helps to break down that organic matter, recycling nutrients in the ecosystem and preventing wildfires fueled by too much leaf litter on the ground. The animals also provide tasty meals for the predators of the steppe, Zuther said. []
"Where you find saiga, we recognize also that the other species are much more abundant," Zuther told Live Science.
Saigas, which are listed as critically endangered by the , live in a few herds in Kazakhstan, one small herd in Russia and a herd in Mongolia. The herds congregate with other herds during the cold winters, as well as when they migrate to other parts of Kazakhstan, during the fall and spring. The herds split up to calve their young during the late spring and early summer. The die-off started during the calving period.
Die-offs of saigas, including one that felled 12,000 of the stately creatures last year, have occurred frequently in recent years. But the large expanse of the country affected by last year's die-off meant veterinarians couldn't get to the animals until long after their deaths. The delay hindered any determination of a cause of death, and researchers eventually speculated that an abundance of greenery caused digestion problems, which led to bacterial overgrowth in the animals' guts.
Detailed analysis
This time, field workers were already on the ground, so they were able to take detailed samples of the saigas' environment — the rocks the animals walked on and the soil they crossed — as well as the water the animals drank and the vegetation they ate in the months and weeks leading up to the die-off. The scientists also took samples of the ticks and other insects that feed on saiga, hoping to find some triggering cause.
The researchers additionally conducted high-quality , and even observed the behavior of some of the animals as they died. The females, which cluster together to calve their young, were hit the hardest. They died first, followed by their calves, which were still too young to eat any vegetation. That sequence suggested that whatever was killing off the animals was being transmitted through the mothers' milk, Zuther said.
Tissue samples revealed that toxins, produced by Pasteurella and possibly Clostridia bacteria, caused extensive bleeding in most of the animals' organs. But Pasteurella is found normally in the bodies of ruminants like the saigas, and it usually doesn't cause harm unless the animals have weakened .
Genetic analysis so far has only deepened the mystery, as the bacteria found were the garden-variety, disease-causing type.
"There is nothing so special about it. The question is why it developed so rapidly and spread to all the animals," Zuther said.
Mystery endures
A similar mass die-off of 400,000 saigas occurred in 1988, and veterinarians reported similar symptoms. But because that die-off occurred during Soviet times, researchers simply listed Pasteurellosis, the disease caused by Pasteurella, as the cause and performed no other investigation, Zuther added.
So far, the only possible environmental cause was that there was a followed by a wet spring, with lots of lush vegetation and standing water on the ground that could enable bacteria to spread more easily, Zuther said. That by itself doesn't seem so unusual, though, he said.
Another possibility is that such flash crashes are inevitable responses to some natural variations in the environment, he said. Zuther said he and his colleagues plan to continue their search for a cause of the die-off.
Back to bottling my Grenache
It started in late May.
When geoecologist Steffen Zuther and his colleagues arrived in central Kazakhstan to monitor the calving of one herd of saigas, a , steppe-dwelling antelope, veterinarians in the area had already reported dead animals on the ground.
"But since there happened to be die-offs of limited extent during the last years, at first we were not really alarmed," Zuther, the international coordinator of the Altyn Dala Conservation Initiative, told Live Science.
But within four days, the entire herd — 60,000 — had died. As veterinarians and conservationists tried to stem the die-off, they also got word of similar population crashes in other herds across Kazakhstan. By early June, the mass dying was over. []
Now, the researchers have found clues as to how more than half of the country's herd, counted at 257,000 as of 2014, died so rapidly. Bacteria clearly played a role in the saigas' demise. But exactly how these normally harmless microbes could take such a toll is still a mystery, Zuther said.
"The extent of this die-off, and the speed it had, by spreading throughout the whole calving herd and killing all the animals, this has not been observed for any other species," Zuther said. "It's really unheard of."
Crucial steppe players
Saigas play a critical role in the ecosystem of the arid grassland steppe, where the cold winters prevent fallen plant material from decomposing; the grazing of the dog-size, Gonzo-nosed antelopes helps to break down that organic matter, recycling nutrients in the ecosystem and preventing wildfires fueled by too much leaf litter on the ground. The animals also provide tasty meals for the predators of the steppe, Zuther said. []
"Where you find saiga, we recognize also that the other species are much more abundant," Zuther told Live Science.
Saigas, which are listed as critically endangered by the , live in a few herds in Kazakhstan, one small herd in Russia and a herd in Mongolia. The herds congregate with other herds during the cold winters, as well as when they migrate to other parts of Kazakhstan, during the fall and spring. The herds split up to calve their young during the late spring and early summer. The die-off started during the calving period.
Die-offs of saigas, including one that felled 12,000 of the stately creatures last year, have occurred frequently in recent years. But the large expanse of the country affected by last year's die-off meant veterinarians couldn't get to the animals until long after their deaths. The delay hindered any determination of a cause of death, and researchers eventually speculated that an abundance of greenery caused digestion problems, which led to bacterial overgrowth in the animals' guts.
Detailed analysis
This time, field workers were already on the ground, so they were able to take detailed samples of the saigas' environment — the rocks the animals walked on and the soil they crossed — as well as the water the animals drank and the vegetation they ate in the months and weeks leading up to the die-off. The scientists also took samples of the ticks and other insects that feed on saiga, hoping to find some triggering cause.
The researchers additionally conducted high-quality , and even observed the behavior of some of the animals as they died. The females, which cluster together to calve their young, were hit the hardest. They died first, followed by their calves, which were still too young to eat any vegetation. That sequence suggested that whatever was killing off the animals was being transmitted through the mothers' milk, Zuther said.
Tissue samples revealed that toxins, produced by Pasteurella and possibly Clostridia bacteria, caused extensive bleeding in most of the animals' organs. But Pasteurella is found normally in the bodies of ruminants like the saigas, and it usually doesn't cause harm unless the animals have weakened .
Genetic analysis so far has only deepened the mystery, as the bacteria found were the garden-variety, disease-causing type.
"There is nothing so special about it. The question is why it developed so rapidly and spread to all the animals," Zuther said.
Mystery endures
A similar mass die-off of 400,000 saigas occurred in 1988, and veterinarians reported similar symptoms. But because that die-off occurred during Soviet times, researchers simply listed Pasteurellosis, the disease caused by Pasteurella, as the cause and performed no other investigation, Zuther added.
So far, the only possible environmental cause was that there was a followed by a wet spring, with lots of lush vegetation and standing water on the ground that could enable bacteria to spread more easily, Zuther said. That by itself doesn't seem so unusual, though, he said.
Another possibility is that such flash crashes are inevitable responses to some natural variations in the environment, he said. Zuther said he and his colleagues plan to continue their search for a cause of the die-off.
Back to bottling my Grenache
Miragedriver
Brigadier
'Ah, Mr Putin I've been expecting you': Russian President Vladimir Putin shows his soft, caring side as he cuddles a fluffy kitten during a visit to a house being rebuilt for people affected by wildfires in the village of Krasnopolye at the Siberian Khakasiya region, Russia
Picture: REUTERS/Alexei Druzhinin/RIA Novosti/Kremlin
Back to bottling my Grenache
Miragedriver
Brigadier
Floating Spoon Spotted On Mars?
NASA says it has an explanation for the levitating utensil.
Of all the strange things people think they've seen in images of Mars -- from to -- this might be the oddest one yet: a spoon that appears to be hovering just above the surface of the Red Planet.
Here's the “spoon,” seen in a NASA image taken by the Curiosity rover's on Aug. 30 (the circle has been added for emphasis;
But though it certainly looks spoon-like, it is, of course, not a spoon. It's not actually floating, either, for that matter.
NASA says the unique -- and very familiar -- form is likely a ventifact, or . (The space agency , along with some examples of them here on Earth as well as on Mars.)
Back to bottling my Grenache
NASA says it has an explanation for the levitating utensil.
Of all the strange things people think they've seen in images of Mars -- from to -- this might be the oddest one yet: a spoon that appears to be hovering just above the surface of the Red Planet.
Here's the “spoon,” seen in a NASA image taken by the Curiosity rover's on Aug. 30 (the circle has been added for emphasis;
But though it certainly looks spoon-like, it is, of course, not a spoon. It's not actually floating, either, for that matter.
NASA says the unique -- and very familiar -- form is likely a ventifact, or . (The space agency , along with some examples of them here on Earth as well as on Mars.)
Back to bottling my Grenache
Miragedriver
Brigadier
Images that capture the incredible vastness of space
1) The sun is incomprehensibly huge
2) From Mars, Earth looks like a tiny blip in the sky
3) Even a single comet is big
4) Other stars are utterly gigantic
Back to bottling my Grenache
1) The sun is incomprehensibly huge
2) From Mars, Earth looks like a tiny blip in the sky
3) Even a single comet is big
4) Other stars are utterly gigantic
Back to bottling my Grenache
Miragedriver
Brigadier
The Coolest New 'Star Wars' Toys From Force Friday
The isn't the only hi-tech bit of merchandise hitting toy stores in the run up to the release of this Christmas: Disney has also unveiled a pair of authentic-looking drones to let you take to the skies.
The drones are manufactured by specialists , and you can pick from the X-Wing famously piloted by Luke Skywalker or the Millennium Falcon that Han Solo and Chewbacca like to leap around the galaxy in.
Both drones come with authentic features and lights - the Millennium Falcon even has a special hyper-drive "stunt", but we're not sure exactly what that entails (presumably it doesn't disappear in a puff of rocket smoke).
The drones you're looking for
The two drones are part of a huge merchandising push on the part of Disney as the release date for JJ Abrams' movie draws closer, involving Lego spaceships, kids' costumes and full-size lightsaber toys you can use to battle the dark or light side of the Force as you wish.
A mammoth was streamed live over YouTube and various retail outlets are using the officially sanctioned Force Friday name to try and flog some Star Wars-related goodies - and we think these drones and BB-8 are the pick of the bunch.
Speaking of retail outlets, the X-Wing and Millennium Falcon drones are on sale now in the US for US$109.99 (roughly £72 and AUS$) and US$69.99 (roughly £46 and AUS$) respectively. We haven't seen them appear elsewhere yet but we would expect them to be available internationally very soon.
Back to bottling my Grenache
The isn't the only hi-tech bit of merchandise hitting toy stores in the run up to the release of this Christmas: Disney has also unveiled a pair of authentic-looking drones to let you take to the skies.
The drones are manufactured by specialists , and you can pick from the X-Wing famously piloted by Luke Skywalker or the Millennium Falcon that Han Solo and Chewbacca like to leap around the galaxy in.
Both drones come with authentic features and lights - the Millennium Falcon even has a special hyper-drive "stunt", but we're not sure exactly what that entails (presumably it doesn't disappear in a puff of rocket smoke).
The drones you're looking for
The two drones are part of a huge merchandising push on the part of Disney as the release date for JJ Abrams' movie draws closer, involving Lego spaceships, kids' costumes and full-size lightsaber toys you can use to battle the dark or light side of the Force as you wish.
A mammoth was streamed live over YouTube and various retail outlets are using the officially sanctioned Force Friday name to try and flog some Star Wars-related goodies - and we think these drones and BB-8 are the pick of the bunch.
Speaking of retail outlets, the X-Wing and Millennium Falcon drones are on sale now in the US for US$109.99 (roughly £72 and AUS$) and US$69.99 (roughly £46 and AUS$) respectively. We haven't seen them appear elsewhere yet but we would expect them to be available internationally very soon.
Back to bottling my Grenache
A friend, historian ( by now two PhD's, one from Leiden University, that was founded to provide protestant clergy during the Dutch revolution in the 16th century, one from the Catholic University in Washington DC ) told about an episode during the Migration Period in the 6th century. A tribe travelled through the whole of Italy and then took ship to Libya (!), which is why their number is known. She asked me to guess the number. I guessed one thousand. She then said it was six hundred. Some contrast with the current situation.
Jura The idiot
General
hey, delft, what does it mean? new Migration Period has begun maybe?
EDIT
by the way, what tribe was that? I would think they took the wrong way
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