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Estamos viviendo el siglo de la Biología evolucionista.
harvestheart: Evolutionary Clock - Illustrator Andreas Preis

harvestheart:

Evolutionary Clock - Illustrator Andreas Preis

Astronomers discover “missing link” of black holes

A composite image of our neighbouring galaxy, Andromeda, showing different views of the Ultraluminous X-ray (ULX) source. Image Credit: X-rays: ESA/M. Middleton et al., Radio: NRAO/M. Middleton et al., Optical: Aladin/STScI DSS. Click to enlarge, see below to download higher resolution.

The discovery of a bingeing black hole in our nearest neighbouring galaxy, Andromeda, has shed new light on some of the brightest X-ray sources seen in other galaxies, according to new work co-authored by astronomers from the International Centre for Radio Astronomy Research’s Curtin University node.

Using a suite of Earth-orbiting X-ray telescopes, including NASA’s Swift and the European Space Agency’s XMM-Newton satellites, a large international team of astronomers watched as the X-ray emission from the black hole – found over 2million light years away – brightened and faded over the course of six months.

The study, published in the prestigious scientific journal Nature, also shows what happens when black holes feast rapidly on the material stripped from a companion star.

It is the second Ultraluminous X-Ray source (ULX) to have been spotted in Andromeda – the Milky Way’s nearest neighboring galaxy – in the past two years.

X-ray telescopes have shown many nearby galaxies to host ULX sources, which can be bright enough to outshine an entire galaxy in X-rays.

Astronomers have spent years debating whether these are black holes just a few times the mass of the Sun which are gorging themselves on gas from an orbiting star, or whether they are more massive black holes eating more sedately.

Lead author Dr Matthew Middleton, who led the latest research while at Durham University, said the findings helped solve this debate.

Dr Middleton, now based at the University of Amsterdam, said: “The black hole we observed in Andromeda is the missing link.

“Our observations tell us that this ultraluminous X-ray source – and by extension, many others – is just a run-of-the-mill black hole, only about ten times the mass of the Sun, that is swallowing material as fast as it can.”

Dr Middleton added: “We watched a black hole go from nibbling daintily at an appetiser to bingeing on the main course, and then gradually slowing down over dessert.”

Black holes in our own Milky Way galaxy are very rarely seen to binge, but when they do, they also launch very powerful beams of material called jets, which are blasted outwards at close to the speed of light, and can be tracked using sensitive radio telescopes.

The team trained the National Science Foundation’s Karl G. Jansky Very Large Array on the black hole, and saw extremely bright radio emission that dropped by a half in just 30 minutes.

“Discovering these radio waves from an ultraluminous X-ray source is the smoking gun, a dead giveaway that these are just normal, everyday black holes,” said co-author Dr James Miller-Jones, of the Curtin University node of the International Centre for Radio Astronomy Research in Perth, Australia.

“This tells us that the region producing radio waves is extremely small in size, no further across than the distance between Jupiter and the Sun.”

This finding was confirmed by zooming in using the world’s most eagle-eyed radio telescope, the Very Long Baseline Array.

This was the first time that radio jets had been detected from a stellar-mass black hole outside our own Milky Way galaxy.

Despite the large distance to Andromeda, the absence of dust and gas in that direction allows an unhindered view of the feast, giving scientists key new insights into how jets are produced by a binging black hole.

Co-author Dr Natasha Hurley-Walker, also from the Curtin University node of the International Centre for Radio Astronomy Research, said: “We were very lucky that this ULX appeared in our local neighbourhood; its proximity meant that we could make these radio observations and demonstrate that the black hole emitting the X-rays is fairly small.”

ICRAR is a joint venture between Curtin University and The University of Western Australia providing research excellence in the field of radio astronomy.

Original Publication: Bright radio emission from an ultraluminous stellar-mass microquasar in M31, by Middleton, MJ, et al is published in Nature. DOI: 10.1038/nature11697

TOP IMAGE….A composite image of our neighbouring galaxy, Andromeda, showing different views of the Ultraluminous X-ray (ULX) source. The background image is an optical (visible) light picture of Andromeda, with the X-ray image (bottom left) taken with the Earth-orbiting XMM-Newton X-ray telescope superimposed. Colours in the X-ray image correspond to different X-ray energies, with red being least energetic and blue being most energetic. The ULX is indicated by the cross-hairs. At the top right is the radio image of the black hole taken with the Very Long Baseline Array radio telescope, showing that the radio emission was coming from an extremely small region of space, and leading the team to infer that the extraordinary amount of X-ray emission they observed was produced by a relatively modest-sized black hole. Image Credit: X-rays: ESA/M. Middleton et al., Radio: NRAO/M. Middleton et al., Optical: Aladin/STScI DSS.
LOWER IMAGE….the Ultraluminous X-ray (ULX) source brightening over time in the X-ray images. Credit: Wolfgang Pietsch, Max-Planck-Institut für extraterrestrische Physik (MPE).

(Source: abcstarstuff, via astro-stoner)

A little brain training goes a long way People who use a ‘brain-workout’ program for just 10 hours have a mental edge over their peers even a year later, researchers report today in PLoS ONE. The search for a regimen of mental callisthenics to stave off age-related cognitive decline is a booming area of research — and a multimillion-dollar business. But critics argue that even though such computer programs can improve performance on specific mental tasks, there is scant proof that they have broader cognitive benefits. For the study, adults aged 50 and older played a computer game designed to boost the speed at which players process visual stimuli. Processing speed is thought to be “the first domino that falls in cognitive decline”, says Fredric Wolinsky, a public-health researcher at the University of Iowa in Iowa City, who led the research. The game was developed by academic researchers but is now sold under the name Double Decision by Posit Science, based in San Francisco, California. (Posit did not fund the study.) Players are timed on how fast they click on an image in the centre of the screen and on others that appear around the periphery. The program ratchets up the difficulty as a player’s performance improves. Participants played the training game for 10 hours on site, some with an extra 4-hour ‘booster’ session later, or for 10 hours at home. A control group worked on computerized crossword puzzles for 10 hours on site. Researchers measured the mental agility of all 621 subjects before the brain training began, and again one year later, using eight well-established tests of cognitive performance. The control group’s scores did not increase over the course of that year, but all the brain-training groups significantly upped their scores in the Useful Field of View test — which requires a subject to identify items in a scene with just a quick glance — and four others. When they compared the study participants’ scores to those expected for people their ages, the researchers found improvements that translated to 3-4.1 years of protection in age-related decline for the field-of-view test and from 1.5-6.6 years for the other tasks. “It was interesting that it didn’t matter whether you were on site at the clinic or just did this at home — you got basically the same bang for your buck,” says Frederick Unverzagt, a neuropsychologist at the Indiana University School of Medicine in Indianapolis, who was not involved with the study. But Peter Snyder, a neuropsychologist at Brown University in Providence, Rhode Island, points out that players’ performance could have improved simply because they were familiar with the game — not because their cognitive skills improved. “To me, that makes it hard to interpret the results with the same degree of certainty” that the authors have, he says. Snyder also doubts that 10 hours of training could affect brain wiring enough to provide long-lasting general benefits, but Henry Mahncke, chief executive of Posit Science, disagrees. “If you’ve never played piano before and spend 10 hours practising, a year later you will be better than when you started,” he says. “The new study shows that there’s science to be done here. Some things you can do with your brain are highly productive and others are not.”

A little brain training goes a long way

People who use a ‘brain-workout’ program for just 10 hours have a mental edge over their peers even a year later, researchers report today in PLoS ONE.

The search for a regimen of mental callisthenics to stave off age-related cognitive decline is a booming area of research — and a multimillion-dollar business. But critics argue that even though such computer programs can improve performance on specific mental tasks, there is scant proof that they have broader cognitive benefits.

For the study, adults aged 50 and older played a computer game designed to boost the speed at which players process visual stimuli. Processing speed is thought to be “the first domino that falls in cognitive decline”, says Fredric Wolinsky, a public-health researcher at the University of Iowa in Iowa City, who led the research.

The game was developed by academic researchers but is now sold under the name Double Decision by Posit Science, based in San Francisco, California. (Posit did not fund the study.) Players are timed on how fast they click on an image in the centre of the screen and on others that appear around the periphery. The program ratchets up the difficulty as a player’s performance improves.

Participants played the training game for 10 hours on site, some with an extra 4-hour ‘booster’ session later, or for 10 hours at home. A control group worked on computerized crossword puzzles for 10 hours on site. Researchers measured the mental agility of all 621 subjects before the brain training began, and again one year later, using eight well-established tests of cognitive performance.

The control group’s scores did not increase over the course of that year, but all the brain-training groups significantly upped their scores in the Useful Field of View test — which requires a subject to identify items in a scene with just a quick glance — and four others. When they compared the study participants’ scores to those expected for people their ages, the researchers found improvements that translated to 3-4.1 years of protection in age-related decline for the field-of-view test and from 1.5-6.6 years for the other tasks.

“It was interesting that it didn’t matter whether you were on site at the clinic or just did this at home — you got basically the same bang for your buck,” says Frederick Unverzagt, a neuropsychologist at the Indiana University School of Medicine in Indianapolis, who was not involved with the study.

But Peter Snyder, a neuropsychologist at Brown University in Providence, Rhode Island, points out that players’ performance could have improved simply because they were familiar with the game — not because their cognitive skills improved. “To me, that makes it hard to interpret the results with the same degree of certainty” that the authors have, he says.

Snyder also doubts that 10 hours of training could affect brain wiring enough to provide long-lasting general benefits, but Henry Mahncke, chief executive of Posit Science, disagrees. “If you’ve never played piano before and spend 10 hours practising, a year later you will be better than when you started,” he says. “The new study shows that there’s science to be done here. Some things you can do with your brain are highly productive and others are not.”

(Source: neurosciencestuff)

llbwwb: Love story by Liron Hamelnick

llbwwb:

Love story by Liron Hamelnick