May 16, 2017 at 12:48 am #1502
Space just got even deadlier.
13 MAY 2017
Were you to look up in the sky roughly 2 million years ago you would have seen a star die in a spectacular blaze of glory.
It’s long been debated whether this supernova explosion would have been close enough to impact life on Earth, and now physicists have shown that while it most likely wouldn’t have triggered mass extinctions, it would have been a pretty bad day for Earthlings.
The new study also updates the distance at which a supernova could be deadly for life on Earth – it was previously thought a supernova would have to be around 25 light-years away to trigger mass extinctions, but the new paper suggests even a supernova 50 light-years away could be deadly.
Back in 2016, scientists announced they’d discovered traces of the isotope iron-60 in ancient ocean sediments and lunar soil, confirming a series of supernovae that lit up the sky between 3.2 and 1.7 million years ago.
Rough estimates put the supernovae at around 100 parsecs, or roughly 330 light-years away, suggesting they would have been visible during the day and about as bright as the Moon.
Since then, follow-up studies pretty much cut that distance in half, putting the dying stars about 60 parsecs, or 195 light-years away at the time.
University of Kansas researcher Adrian Melott wondered what this closer series of supernovae might have meant for life on Earth.
“The timing estimates are still not exact, but the thing that changed to cause us to write this paper is the distance. We did this computation because other people did work that made a revised distance estimate, which cut the distance in half,” said Melott.
Supernovae occur when massive stars run out of fuel and collapse, resulting in a surge of energy that blasts a shock wave of radiation and particles across interstellar space.
Space is pretty damn big, so our Solar System rarely gets close enough to such awesome stellar events for that radiation and shower of high-speed radiation to be a problem for delicate biochemistry on our planet’s surface.
But what exactly is close enough?
Melott and a team of researchers considered current evaluations on how close a supernova needed to be for Earth’s biosphere to be within its “kill zone”, and argued we might want to expand it a little.
“People estimated the ‘kill zone’ for a supernova in a paper in 2003, and they came up with about 25 light-years from Earth,” said Melott.
“Now we think maybe it’s a bit greater than that. They left some effects out or didn’t have good numbers, so now we think it may be a bit larger distance.”
Keeping in mind it would be a gradual rise in deaths resulting from cosmic rays, Melott and his colleagues now think a supernova even 40 to 50 light-years away would probably cause some serious carnage.
In spite of that bigger bubble of death and halving of their estimated distance, the supernovae that took place around 2.6 million years ago still wouldn’t have been close enough to give rise to any mass extinctions.
Fossils happen to back this up. Melott’s colleagues dug into Africa’s fossil record on account of it being so geologically stable at the time of the supernovae, finding no solid evidence for a wide-spread die-off.
“There isn’t a mass extinction, but there is kind of a lot of extinction going on at that time and species turnover,” said Melott.
How much is due to a changing climate and how much to an increase in cosmic rays is kind of hard to tell.
So now we have some supernovae a few million years ago just 200-odd light years away which didn’t cause a bunch of stuff to die. To get a better idea of what headaches – if any – the exploding stars would have caused, the researchers considered the mechanisms behind a spreading wave of deadly particles and radiation.
It turns out this is a little more complicated than we might first assume – far from being a simple tsunami of gamma rays and neutrons cranked up to a fraction of light speed, it all depends on the magnetic fields between us and the star.
“If there’s a magnetic field, we don’t know its orientation, so it can either create a superhighway for cosmic rays, or it could block them,” said Melott.
Melott and his team assumed the supernova created its own ‘bubble’ of field lines, which Earth would fall inside as it expanded.
Far from providing a ‘highway’, those magnetic fields would be wiggling like a bowl of spaghetti.
Or as Melott put it, “The best analogy I can think of is more like off-road driving”.
The results wouldn’t have been deadly, but might still have been spectacular. Cosmic rays striking our atmosphere still would shed a weak, blue glow that would be visible at night, potentially affecting the sleep cycles of some diurnal animals.
Elementary particles would also be penetrating down as far as the troposphere, with some making it to the ground where they could give all life the equivalent of a couple of CT scans in radiation.
Not bad, but a number of unfortunate mammoths and sloths could find themselves with an extra tumour or two as a result.
Lastly, cascades of particle interactions in the atmosphere are known to promote conditions just right for lightning, leading to more strikes that could cause more frequent fires.
The research can currently be found on the pre-publishing website arXiv.org, but is due to be published in Astrophysical Journal.
The closest star which could go supernova any time soon, a red giant called Betelgeuse, is about 650 light years away, so should we warn people to start digging bunkers?
“I tell them they should worry about global warming and nuclear war, not this stuff,” said Mellett.May 16, 2017 at 8:58 pm #1514
What is deadly is reading the internet and mistaking it for your life.May 18, 2017 at 3:25 am #1516May 18, 2017 at 2:20 pm #1517
One of the greatest practical barriers to spiritual advancement is having a big idea about it, it’s not a lot more than becoming normal and sane and knowing oneself.
But people always dream big with gods and stars and energies and powers … and then they die never having taken a simple step foreward and with their minds full of pictures.May 18, 2017 at 3:31 pm #1518
Sorry, but my intention is not to send any disturbing non-Taoist material.
Brains of Buddhist monks scanned in meditation study
By Matt Danzico BBC News, New York24 April 2011
From the section US & Canada
In a laboratory tucked away off a noisy New York City street, a soft-spoken neuroscientist has been placing Tibetan Buddhist monks into a car-sized brain scanner to better understand the ancient practice of meditation.
But could this unusual research not only unravel the secrets of leading a harmonious life but also shed light on some of the world’s more mysterious diseases?
Zoran Josipovic, a research scientist and adjunct professor at New York University, says he has been peering into the brains of monks while they meditate in an attempt to understand how their brains reorganise themselves during the exercise.
Since 2008, the researcher has been placing the minds and bodies of prominent Buddhist figures into a five-tonne (5,000kg) functional magnetic resonance imaging (fMRI) machine.
The scanner tracks blood flow within the monks’ heads as they meditate inside its clunky walls, which echoes a musical rhythm when the machine is operating.
Dr Josipovic, who also moonlights as a Buddhist monk, says he is hoping to find how some meditators achieve a state of “nonduality” or “oneness” with the world, a unifying consciousness between a person and their environment.
“One thing that meditation does for those who practise it a lot is that it cultivates attentional skills,” Dr Josipovic says, adding that those harnessed skills can help lead to a more tranquil and happier way of being.
“Meditation research, particularly in the last 10 years or so, has shown to be very promising because it points to an ability of the brain to change and optimise in a way we didn’t know previously was possible.”
When one relaxes into a state of oneness, the neural networks in experienced practitioners change as they lower the psychological wall between themselves and their environments, Dr Josipovic says.
And this reorganisation in the brain may lead to what some meditators claim to be a deep harmony between themselves and their surroundings.
Dr Josipovic’s research is part of a larger effort better to understand what scientists have dubbed the default network in the brain.
He says the brain appears to be organised into two networks: the extrinsic network and the intrinsic, or default, network.
The extrinsic portion of the brain becomes active when individuals are focused on external tasks, like playing sports or pouring a cup of coffee.
The default network churns when people reflect on matters that involve themselves and their emotions.
But the networks are rarely fully active at the same time. And like a seesaw, when one rises, the other one dips down.
This neural set-up allows individuals to concentrate more easily on one task at any given time, without being consumed by distractions like daydreaming.
“What we’re trying to do is basically track the changes in the networks in the brain as the person shifts between these modes of attention,” Dr Josipovic says.
Dr Josipovic has found that some Buddhist monks and other experienced meditators have the ability to keep both neural networks active at the same time during meditation – that is to say, they have found a way to lift both sides of the seesaw simultaneously.
And Dr Josipovic believes this ability to churn both the internal and external networks in the brain concurrently may lead the monks to experience a harmonious feeling of oneness with their environment.
Scientists previously believed the self-reflective, default network in the brain was simply one that was active when a person had no task on which to focus their attention.
But researchers have found in the past decade that this section of the brain swells with activity when the subject thinks about the self.
The default network came to light in 2001 when Dr Marcus Raichle, a neurologist at the Washington University School of Medicine in the US state of Missouri, began scanning the brains of individuals who were not given tasks to perform.
The patients quickly became bored, and Dr Raichle noticed a second network, that had previously gone unnoticed, danced with activity. But the researcher was unclear why this activity was occurring.
Other scientists were quick to suggest that Dr Raichle’s subjects could have actually been thinking about themselves.
Soon other neuroscientists, who conducted studies using movies to stimulate the brain, found that when there was a lull of activity in a film, the default network began to flash – signalling that research subjects may have begun to think about themselves out of boredom.
But Dr Raichle says the default network is important for more than just thinking about what one had for dinner last night.
“Researchers have wrestled with this idea of how we know we are who we are. The default mode network says something about how that might have come to be,” he says.
And Dr Raichle adds that those studying the default network may also help in uncovering the secrets surrounding some psychological disorders, like depression, autism and even Alzheimer’s disease.
“If you look at Alzheimer’s Disease, and you look at whether it attacks a particular part of the brain, what’s amazing is that it actually attacks the default mode network,” says Dr Raichle, adding that intrinsic network research, like Dr Josipovic’s, could assist in explaining why that is.
Cindy Lustig, associate professor of psychology and neuroscience at the University of Michigan, agrees.
“It’s a major and understudied network in the brain that seems to be very involved in a lot of neurological disorders, including autism and Alzheimer’s, and understanding how that network interacts with the task-oriented [extrinsic] network is important,” she says. “It is sort of the other piece of the puzzle that’s been ignored for too long.”
Dr Josipovic has scanned the brains of more than 20 experienced meditators, both monks and nuns who primarily study the Tibetan Buddhist style of meditation, to better understand this mysterious network.
He says his research, which will soon be published, will for the moment continue to concentrate on explaining the neurological implications of oneness and tranquillity – though improving understanding of autism or Alzheimer’s along the way would certainly be quite a bonus.May 19, 2017 at 5:56 pm #1520
Humans use the word “understand” a lot.
But they do not understand.
You would think it was obvious they don’t understand from the rapidly declining state of the planet.
They do not seem to notice.
Instead they continue to talk about “understanding” a lot.May 20, 2017 at 2:44 am #1522
Understanding the architecture of our ‘second brain’
May 19, 2017
Scientists have made an important step in understanding the organisation of nerve cells embedded within the gut that control its function – a discovery that could give insight into the origin of common gastrointestinal diseases, including irritable bowel syndrome and chronic constipation.
The findings, published in Science, reveal how the enteric nervous system – a chaotic network of half a billion nerve cells and many more supporting cells inside the gut wall – is formed during mouse development. The research was led by the Francis Crick Institute, in collaboration with the University of Leuven, Stanford University, the Hubrecht Institute and the Quadram Institute Bioscience. The work was funded by the Francis Crick Institute, the Medical Research Council and the UK Biotechnology and Biological Sciences Research Council.
Often known as the ‘second brain’ for its vast number of neurons and complex connectivity, the enteric nervous system has a crucial role in maintaining a healthy gut. Therefore, understanding how this neural mosaic is organised could help scientists find treatments for common gastrointestinal disorders.
“The gut wall is home to many types of nerve cells which appear to be distributed randomly,” says Vassilis Pachnis, Group Leader at the Francis Crick Institute. “But despite this chaos, the neural networks of the gut are responsible for well organised and stereotypic functions such as production of stomach acid, movement of food along the gut, communication with immune cells and bacteria, and relay of information to the brain. We wanted to find out how organised activity emerges from such a chaotic system.”
During development, a unique and dynamic population of cells known as progenitor cells divide to produce copies of themselves, which can then generate many other types of cells. Using genetic tools, the team labelled individual progenitor cells of the enteric nervous system with unique colours and followed their descendants – also marked with the same colour – through development and into the adult animal. By examining the type of cells produced by single progenitors, they could understand their properties.
They found that some progenitors only produced nerve cells, others only produced nerve-supporting cells called glia, and some produced both. Neurons and glia originating from the same parent stayed close to each other, forming relatively tight groups of cells. Cell groups that descended from different but neighbouring parent cells overlapped like a Venn diagram that could be viewed on the gut surface. Interestingly, this close relationship was maintained by the descendants of single progenitors down through all layers of the gut wall thereby forming overlapping columns of cells.
“We uncovered a set of rules that control the organisation of the ‘second brain’ not just along a single gut layer but across the 3-D space of the gut wall,” says Reena Lasrado, first author of the paper and researcher in Vassilis’s lab at the Crick.
The team explored whether this intricate structure of the enteric nervous system also contributes to nerve cell activity in the gut.
“A subtle electrical stimulation to the enteric nervous system showed that nerve cells generated by the same parent cell responded in synchrony,” says Vassilis. “This suggests that developmental relationships between cells of the enteric nervous system of mammals are fundamental for the neural regulation of gut function.”
“Now that we have a better understanding of how the enteric nervous system is built and works, we can start to look at what happens when things go wrong particularly during the critical stages of embryo development or early life. Perhaps mistakes in the blueprint used to build the neural networks of the gut are the basis of common gastrointestinal problems.”
The paper ‘Lineage-dependent spatial and functional organization of the mammalian enteric nervous system’ is published in Science.
More information: Reena Lasrado et al. Lineage-dependent spatial and functional organization of the mammalian enteric nervous system, Science (2017). DOI: 10.1126/science.aam7511
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